feat(backend) update (unfinished)

backend/macros/src/include_str.rs

@@ -0,0 +1,24 @@
+/// Includes a UTF-8 encoded file as a string
+///
+/// The file is located relative to `CARGO_MANIFEST_DIR`.
+///
+/// # Example
+/// ```rust
+/// use macros::include_str_from_crate_root;
+///
+/// let str: &str = include_str_from_crate_root!("/query/scheme.sql");
+///
+// todo: impl
+// const PATH_PREFIX: &str = "/src";
+// let str: &str = include_str_from_crate_root!("{}/query/scheme.sql", PATH_PREFIX);
+/// ```
+#[macro_export]
+macro_rules! include_str_from_crate_root {
+    // ($path:literal $(, $($arg:tt)*)?) => {
+    // ($path:expr, $($args:tt)*) => {
+    //     include_str!(concat!(env!("CARGO_MANIFEST_DIR"), format_args!($path, $($args)*)))
+    // };
+    ($path:expr) => {
+        include_str!(concat!(env!("CARGO_MANIFEST_DIR"), $path))
+    };
+}

backend/macros/src/lib.rs

@@ -1 +1,2 @@
+mod include_str;
 mod log;

backend/server/Cargo.toml

@@ -5,10 +5,24 @@ edition = "2021"
 
 [dependencies]
 macros = { path = "../macros" }
+markdown = { path = "../markdown" }
 
-
+axum = { version = "0.8.1", features = ["macros"] }
-tracing = "0.1.41"
+tracing = { version = "0.1.41", features = ["log"] }
 git2 = "0.20.0"
+chrono = { version = "0.4.39", features = ["serde"] }
+cron = "0.15.0"
+sqlx = { version = "0.8.3", features = ["runtime-tokio", "tls-native-tls", "postgres", "chrono"] }
+serde_json = "1.0.133"
+serde = { version = "1.0.215", features = ["derive"] }
+tracing-subscriber = "0.3.18"
+tracing-appender = "0.2.3"
+dirs = "6.0.0"
+thiserror = "2.0.11"
+tokio = { version = "1.42.0", features = ["rt", "rt-multi-thread", "macros"] }
+dotenv = "0.15.0"
+uuid = { version = "1.13.2", features = ["v4"] }
+futures = "0.3.31"
 
 [build-dependencies]
 git2 = "0.20.0"

backend/server/build.rs

@@ -9,7 +9,8 @@ fn main() {
         .peel_to_commit()
         .expect("failed to get HEAD commit");
     let hash = commit.id().to_string();
-    let utc_date = Utc::now().date_naive().format("%Y%m%d").to_string();
+    let utc_timestamp = Utc::now().date_naive().format("%Y%m%d").to_string();
-    let build_id = format!("{}@{}", utc_date, &hash[..8]);
+    let pkg_version = env!("CARGO_PKG_VERSION");
+    let build_id = format!("{}:{}@{}", pkg_version, &hash[..8], utc_timestamp);
     println!("cargo:rustc-env=BUILD_ID={}", build_id);
 }

backend/server/schema.sql

@@ -1,32 +0,0 @@
-CREATE TABLE tag
-(
-    id          SERIAL PRIMARY KEY,
-    name        VARCHAR(20) UNIQUE NOT NULL,
-    description TEXT
-);
-
-CREATE TABLE category
-(
-    id          SERIAL PRIMARY KEY,
-    name        VARCHAR(20) UNIQUE NOT NULL,
-    description TEXT
-);
-
-CREATE TABLE post
-(
-    id             SERIAL PRIMARY KEY,
-    identifier     VARCHAR(50) UNIQUE              NOT NULL,
-    title          VARCHAR(255)                    NOT NULL,
-    subtitle       VARCHAR(255)                    NOT NULL,
-    published_date DATE                            NOT NULL,
-    last_update    DATE,
-    content        TEXT                            NOT NULL,
-
-    category       SERIAL REFERENCES category (id) NOT NULL
-);
-
-CREATE TABLE post_tag
-(
-    post SERIAL REFERENCES post (id),
-    tag  SERIAL REFERENCES tag (id)
-)

backend/server/src/init/database.rs

@@ -0,0 +1,42 @@
+use std::env;
+use std::error::Error;
+use std::str::FromStr;
+
+use crate::constants::config::database::{default_value, var_name};
+
+use sqlx::postgres::{PgConnectOptions, PgPoolOptions};
+use sqlx::{ConnectOptions, Pool, Postgres};
+use tracing::info;
+
+pub async fn init() -> Result<Pool<Postgres>, Box<dyn Error>> {
+    let db_connect_option = PgConnectOptions::from_str(&parse_db_uri())
+        .unwrap()
+        .disable_statement_logging();
+    Ok(PgPoolOptions::new()
+        .max_connections(1) // todo: temporary solution, to be fixed
+        .connect_with(db_connect_option)
+        .await?)
+}
+
+fn parse_db_uri() -> String {
+    env::var(var_name::URI).unwrap_or_else(|_| {
+        info!(
+            "`{}` env var is not set, \
+            using `{}`, `{}`, `{}`, `{}` and `{}`",
+            var_name::URI,
+            var_name::USERNAME,
+            var_name::PASSWORD,
+            var_name::HOST,
+            var_name::PORT,
+            var_name::DBNAME
+        );
+        let postgres_user = env::var(var_name::USERNAME).unwrap_or(default_value::USERNAME.into());
+        let postgres_password =
+            env::var(var_name::PASSWORD).unwrap_or(default_value::PASSWORD.into());
+        let db_host = env::var(var_name::HOST).unwrap_or(default_value::HOST.into());
+        let db_port = env::var(var_name::PORT).unwrap_or(default_value::PORT.into());
+        let postgres_db = env::var(var_name::DBNAME).unwrap_or(default_value::DBNAME.into());
+        let db_type = default_value::DATABASE_TYPE;
+        format!("{db_type}://{postgres_user}:{postgres_password}@{db_host}:{db_port}/{postgres_db}")
+    })
+}

backend/server/src/init/logger.rs

@@ -0,0 +1,107 @@
+use std::path::Path;
+use std::{env, io};
+
+use crate::constants::config::general::{default_value, var_name};
+
+use chrono::Local;
+use dirs::home_dir;
+use tracing::info;
+use tracing_appender::{non_blocking, non_blocking::WorkerGuard, rolling};
+use tracing_subscriber::{
+    filter::LevelFilter, fmt, fmt::format::Writer, fmt::time::FormatTime, fmt::MakeWriter,
+    layer::SubscriberExt, Layer, Registry,
+};
+
+struct LocalTimer;
+
+impl FormatTime for LocalTimer {
+    fn format_time(&self, w: &mut Writer<'_>) -> std::fmt::Result {
+        write!(
+            w,
+            "{}",
+            Local::now().format(crate::constants::time::DEFAULT_TIME_FORMAT)
+        )
+    }
+}
+
+type _LogWriter = dyn for<'writer> MakeWriter<'writer, Writer = dyn io::Write + 'static> + 'static;
+
+pub fn init() -> (WorkerGuard, WorkerGuard) {
+    let log_path = match env::var(var_name::LOG_DIR) {
+        Ok(path) => Path::new(&path).to_path_buf(),
+        Err(_) => {
+            let path = if let Ok(default_log_path) = env::var(var_name::WORK_DIR) {
+                expand_home_path(default_log_path)
+            } else {
+                let fallback_path = expand_home_path(default_value::WORK_DIR.to_string());
+                println!(
+                    "[warn] unset env var `{}` and `{}`, trying to log on fallback path: {}/log",
+                    var_name::LOG_DIR,
+                    var_name::WORK_DIR,
+                    fallback_path
+                );
+                fallback_path
+            };
+            Path::new(&path).join("log")
+        }
+    };
+
+    let (info_log_writer, info_guard) = non_blocking(rolling::never(&log_path, "info.log"));
+    let (err_log_writer, error_guard) = non_blocking(rolling::never(&log_path, "error.log"));
+
+    let info_format = tracing_subscriber::fmt::format()
+        .with_level(true)
+        .with_target(true)
+        .with_source_location(true)
+        .with_ansi(false);
+    let err_format = tracing_subscriber::fmt::format()
+        .with_level(true)
+        .with_target(true)
+        .with_source_location(true)
+        .with_ansi(false);
+    let stdout_format = tracing_subscriber::fmt::format()
+        .with_level(true)
+        .with_target(true)
+        .with_source_location(true)
+        .with_timer(LocalTimer);
+
+    let subscribers = Registry::default()
+        .with(
+            fmt::Layer::default()
+                .with_writer(info_log_writer)
+                .event_format(info_format),
+        )
+        .with(
+            fmt::Layer::default()
+                .with_writer(err_log_writer)
+                .event_format(err_format)
+                .with_filter(LevelFilter::ERROR),
+        )
+        .with(
+            fmt::Layer::default()
+                .with_writer(io::stdout)
+                .with_ansi(true)
+                .event_format(stdout_format),
+        );
+
+    tracing::subscriber::set_global_default(subscribers)
+        .expect("[fatal] failed to setup logging system");
+
+    info!("logging to dir: {}", log_path.to_str().unwrap());
+
+    (info_guard, error_guard)
+}
+
+fn expand_home_path(path: String) -> String {
+    if path.starts_with('~') {
+        let home_path = home_dir()
+            .unwrap_or_else(|| panic!("[fatal] unable to locate home dir when parsing env `{}`, try to use absolute path instead", var_name::WORK_DIR));
+        home_path
+            .join(path.strip_prefix("~/").unwrap())
+            .into_os_string()
+            .into_string()
+            .unwrap()
+    } else {
+        path
+    }
+}

backend/server/src/init/misc.rs

@@ -0,0 +1,14 @@
+use git2::opts::{set_server_connect_timeout_in_milliseconds, set_server_timeout_in_milliseconds};
+use tracing::warn;
+
+pub fn init() {
+    // git2 option
+    unsafe {
+        if let Err(e) = set_server_connect_timeout_in_milliseconds(10_000) {
+            warn!("failed to set git2 server connect timeout: {}", e);
+        }
+        if let Err(e) = set_server_timeout_in_milliseconds(60_000) {
+            warn!("failed to set git2 server timeout: {}", e);
+        }
+    }
+}

backend/server/src/init/mod.rs

@@ -0,0 +1,50 @@
+mod database;
+pub mod logger;
+mod misc;
+
+use std::{env, panic};
+
+use crate::modules::{blog::Blog, ModuleTree};
+use macros::error_panic;
+
+use tracing::info;
+
+pub fn load_env() {
+    if let Some(env_file) = env::args().nth(1) {
+        match dotenv::from_filename(&env_file) {
+            Ok(_) => {
+                println!("[info] env loaded from {}, starting up", env_file);
+            }
+            Err(e) => {
+                panic!("[fatal] failed to read {}: {}", env_file, e);
+            }
+        }
+    } else {
+        println!("[info] no .env file referred, starting up")
+    }
+}
+
+pub async fn start() {
+    misc::init();
+
+    // connect database
+    let db_pool = match database::init().await {
+        Ok(pool) => {
+            info!("database connection pool initialized");
+            pool
+        }
+        Err(e) => {
+            error_panic!("database connection pool failed to initialize: {}", e);
+        }
+    };
+
+    // // schema init
+    // schema::init(&db_pool).await;
+
+    ModuleTree::new()
+        .add_module(Blog {
+            db_handler: db_pool,
+        })
+        .blocking_serve()
+        .await
+}

backend/server/src/main.rs

@@ -1,7 +1,23 @@
+#[allow(dead_code)]
 mod constants;
 
+#[allow(dead_code)]
+mod scheduler;
+
+mod init;
+mod modules;
+mod utils;
+
+use crate::init::{logger, start};
+
 const BUILD_ID: &str = env!("BUILD_ID");
 
-fn main() {
+#[tokio::main]
+async fn main() {
     println!("{}", BUILD_ID);
+
+    init::load_env();
+    let _guards = logger::init();
+
+    start().await;
 }

backend/server/src/modules/blog/api/get_page_count/mod.rs

@@ -0,0 +1,25 @@
+use crate::constants::blog::PAGE_SIZE;
+
+use axum::{extract::State, Json};
+use serde_json::{json, Value};
+use sqlx::{query, PgPool, Row};
+use tracing::error;
+
+const GET_PAGE_COUNT_QUERY: &str = include_str!("post_page_count.sql");
+
+pub async fn handler(State(db_connection): State<PgPool>) -> Result<Json<Value>, Json<Value>> {
+    match query(GET_PAGE_COUNT_QUERY)
+        .bind(PAGE_SIZE as i64)
+        .fetch_one(&db_connection)
+        .await
+    {
+        Ok(res) => {
+            let res: i32 = res.get("count");
+            Ok(Json::from(json!({"res": res})))
+        }
+        Err(e) => {
+            error!("failed to get blog page count: {}", e.to_string());
+            Err(Json::from(json!({"error": e.to_string()})))
+        }
+    }
+}

backend/server/src/modules/blog/api/get_page_count/post_page_count.sql

@@ -0,0 +1,2 @@
+SELECT cast(ceil(count(*) / cast($1 AS FLOAT)) AS INTEGER) AS count
+FROM posts;

backend/server/src/modules/blog/api/get_post/mod.rs

@@ -0,0 +1,30 @@
+use axum::response::IntoResponse;
+use axum::{
+    extract::{Path, State},
+    Json,
+};
+use serde_json::json;
+use sqlx::PgPool;
+
+const GET_POST_BY_I64_ID: &str = include_str!("get_post_by_i64_id.sql");
+const GET_POST_BY_STR_ID: &str = include_str!("get_post_by_str_id.sql");
+
+pub async fn handler(
+    State(db_connection): State<PgPool>,
+    Path(identifier): Path<String>,
+) -> impl IntoResponse {
+    let post = if let Ok(id) = identifier.parse::<i64>() {
+        select_post_with_i64_id(&db_connection, id).await
+    } else {
+        select_post_with_str_id(&db_connection, &identifier).await
+    };
+    Json::from(json!({"res": "ok"})).into_response()
+}
+
+async fn select_post_with_i64_id(db: &PgPool, id: i64) {
+    todo!()
+}
+
+async fn select_post_with_str_id(db: &PgPool, id: &str) {
+    todo!()
+}

backend/server/src/modules/blog/api/get_post_list.rs

@@ -0,0 +1,130 @@
+use std::error::Error;
+
+use crate::constants::blog::PAGE_SIZE;
+
+use axum::{extract::Query, extract::State, http::StatusCode, Json};
+use chrono::{DateTime, Utc};
+use futures::future::join_all;
+use serde::Deserialize;
+use serde_json::{json, Map, Value};
+use sqlx::{postgres::PgRow, query, PgPool, Row};
+use tracing::error;
+use uuid::Uuid;
+
+#[derive(Deserialize)]
+pub struct Params {
+    page: Option<u32>,
+}
+
+#[axum::debug_handler]
+pub async fn get_post_list(
+    State(db_connection): State<PgPool>,
+    Query(params): Query<Params>,
+) -> Result<Json<Value>, (StatusCode, Json<Value>)> {
+    let search_param_page = params.page.unwrap_or(1);
+    if search_param_page < 1 {
+        return Err((
+            StatusCode::BAD_REQUEST,
+            Json::from(json!({"error": "`page` should be greater than 0"})),
+        ));
+    }
+
+    let offset = PAGE_SIZE * (search_param_page - 1);
+
+    let post_list = sqlx::query("SELECT * FROM post ORDER BY first_update DESC LIMIT $1 OFFSET $2")
+        .bind(PAGE_SIZE as i32)
+        .bind(offset as i32)
+        .fetch_all(&db_connection)
+        .await;
+    let post_list = match post_list {
+        Ok(post_list) => post_list,
+        Err(e) => {
+            error!(
+                "Database query error on fetching post list: {}",
+                e.to_string()
+            );
+            return Err((
+                StatusCode::INTERNAL_SERVER_ERROR,
+                Json::from(json!({"error": e.to_string()})),
+            ));
+        }
+    };
+
+    let mut res = Vec::new();
+    let posts: Vec<_> = post_list
+        .into_iter()
+        .map(|post| async { analyze_post(&db_connection, post).await })
+        .collect();
+    let posts = join_all(posts).await;
+    for post in posts {
+        match post {
+            Ok(p) => res.push(p),
+            Err(e) => {
+                return Err((
+                    StatusCode::INTERNAL_SERVER_ERROR,
+                    Json::from(json!(("error", e.to_string()))),
+                ))
+            }
+        }
+    }
+
+    // res.insert("posts".to_string(), Value::from(posts));
+    Ok(Json::from(Value::from(res)))
+}
+
+async fn analyze_post(db_connection: &PgPool, post: PgRow) -> Result<Value, Box<dyn Error + Send>> {
+    let post_id: Uuid = post.get("post_id");
+    let tags = fetch_post_tags(db_connection, post_id).await;
+    let meta = fetch_post_meta(db_connection, post_id).await.unwrap();
+    let header_img = meta.get("header_img");
+    let last_update = meta.get("last_update");
+
+    Ok(json!({
+        "post_id": post_id.to_string(),
+        "title": post.get::<String, _>("title"),
+        "category": post.get::<String, _>("category"),
+        "header_img": header_img,
+        "sub_title": post.get::<String, _>("sub_title"),
+        "summary": post.get::<String, _>("summary"),
+        "last_update": last_update,
+        "first_update": post.get::<DateTime<Utc>, _>("first_update"),
+        "tags": tags,
+    }))
+}
+
+async fn fetch_post_meta(db_connection: &PgPool, post_id: Uuid) -> Option<Value> {
+    match query(
+        r#"
+SELECT jsonb_strip_nulls(to_jsonb(t.*)) - 'post_id' AS meta
+FROM meta t
+WHERE post_id = $1;
+        "#,
+    )
+    .bind(post_id)
+    .fetch_one(db_connection)
+    .await
+    {
+        Ok(value) => Some(value.get::<Value, _>("meta")),
+        Err(e) => {
+            error!(
+                "Database error on Reading `{}` from table `{}`: <{}>: {}",
+                "post meta data",
+                "meta",
+                post_id.to_string(),
+                e.to_string()
+            );
+            None
+        }
+    }
+}
+
+async fn fetch_post_tags(db_connection: &PgPool, post_id: Uuid) -> Vec<String> {
+    match query("SELECT tag FROM Tag WHERE post_id = $1")
+        .bind(post_id)
+        .fetch_all(db_connection)
+        .await
+    {
+        Ok(res) => res.iter().map(|tag| tag.get::<String, _>("tag")).collect(),
+        Err(_) => vec![],
+    }
+}

backend/server/src/modules/blog/api/mod.rs

@@ -0,0 +1,3 @@
+pub mod get_page_count;
+pub mod get_post;
+// pub mod get_post_list;

backend/server/src/modules/blog/cron/check_update/error.rs

@@ -0,0 +1,49 @@
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum PostIdxError {
+    #[error("missing essential field `{}` for file `{}`", field, filename)]
+    MissingField { field: String, filename: String },
+
+    #[error(
+        "invalid field `{}` for file `{}`, <{}>: {}",
+        field_name,
+        filename,
+        err_field,
+        msg
+    )]
+    InvalidField {
+        field_name: String,
+        err_field: String,
+        filename: String,
+        msg: String,
+    },
+
+    #[error(
+        "database error on writing `{}` to table `{}`: <{}>: {}",
+        data_desc,
+        db_table,
+        id,
+        msg
+    )]
+    DBWriteFailure {
+        data_desc: String,
+        db_table: String,
+        id: String,
+        msg: String,
+    },
+
+    #[error(
+        "Database error on Reading `{}` from table `{}`: <{}>: {}",
+        data_desc,
+        db_table,
+        id,
+        msg
+    )]
+    DBReadFailure {
+        data_desc: String,
+        db_table: String,
+        id: String,
+        msg: String,
+    },
+}

backend/server/src/modules/blog/cron/check_update/index.rs

@@ -0,0 +1,353 @@
+use std::error::Error;
+use std::path::Path;
+
+use crate::{
+    modules::blog::cron::check_update::utils::get_md_file_basename,
+    modules::blog::cron::check_update::{error::PostIdxError, utils::parse_date},
+};
+use markdown::MdFile;
+
+use sqlx::{query, PgPool, Pool, Postgres, Row};
+use tokio::runtime::Runtime;
+use tracing::{info, warn};
+
+async fn base(db_connection: &PgPool, post: &MdFile) -> Result<(), PostIdxError> {
+    let post_id = post.file_id;
+    let title = match post.meta.get("title") {
+        None => {
+            return Err(PostIdxError::MissingField {
+                field: "title".to_string(),
+                filename: post.filename.clone(),
+            })
+        }
+        Some(title) => title.as_str().unwrap_or_else(|| {
+            warn!("invalid title for `{}`", &post.filename);
+            "invalid title"
+        }),
+    };
+    let sub_title = post
+        .meta
+        .get("sub_title")
+        .and_then(|v| v.as_str())
+        .unwrap_or("");
+    let summary = post
+        .meta
+        .get("summary")
+        .and_then(|v| v.as_str())
+        .unwrap_or("");
+    let content = post.content.as_str();
+    let category = match post.meta.get("category") {
+        None => {
+            return Err(PostIdxError::MissingField {
+                field: "category".to_string(),
+                filename: post.filename.clone(),
+            })
+        }
+        Some(title) => title.as_str().unwrap_or_else(|| {
+            warn!("invalid category for `{}`", &post.filename);
+            "invalid category"
+        }),
+    };
+    let last_update = {
+        if let Some(last_update) = post.meta.get("last_update") {
+            match parse_date(last_update.as_str().unwrap()) {
+                Ok(date) => Some(date),
+                Err(e) => {
+                    return Err(PostIdxError::InvalidField {
+                        field_name: "last_update".to_string(),
+                        err_field: last_update.to_string(),
+                        filename: post.filename.clone(),
+                        msg: e.to_string(),
+                    })
+                }
+            }
+        } else {
+            None
+        }
+    };
+    let first_update = match post.meta.get("date") {
+        None => {
+            return Err(PostIdxError::MissingField {
+                field: "date".to_string(),
+                filename: post.filename.clone(),
+            })
+        }
+        Some(first_update) => match parse_date(first_update.as_str().unwrap()) {
+            Ok(date) => date,
+            Err(e) => {
+                return Err(PostIdxError::InvalidField {
+                    field_name: "date".to_string(),
+                    err_field: first_update.to_string(),
+                    filename: post.filename.clone(),
+                    msg: e.to_string(),
+                })
+            }
+        },
+    };
+    let filename = get_md_file_basename(&post.filename);
+
+    if let Err(e) = query(
+        r##"
+INSERT INTO Post (post_id, title, summary, content, last_update, first_update, sub_title, category, filename)
+VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
+ON CONFLICT (post_id) DO
+UPDATE SET
+    title = EXCLUDED.title,
+    summary = EXCLUDED.summary,
+    content = EXCLUDED.content,
+    last_update = EXCLUDED.last_update,
+    first_update = EXCLUDED.first_update,
+    sub_title = EXCLUDED.sub_title,
+    category = EXCLUDED.category,
+    filename = EXCLUDED.filename;
+        "##,
+    )
+        .bind(post_id)
+        .bind(title)
+        .bind(summary)
+        .bind(content)
+        .bind(last_update)
+        .bind(first_update)
+        .bind(sub_title)
+        .bind(category)
+        .bind(filename)
+        .execute(db_connection)
+        .await
+    {
+        return Err(
+            PostIdxError::DBWriteFailure {
+                data_desc: "post base information".to_string(),
+                db_table: "Post".to_string(),
+                id: post_id.to_string(),
+                msg: e.to_string(),
+            }
+        );
+    }
+    Ok(())
+}
+
+async fn tag(db_connection: &PgPool, post: &MdFile) -> Result<(), PostIdxError> {
+    if let Some(tags_string) = post.meta.get("tags").to_owned() {
+        let tags = match tags_string.as_array().map(|vec| {
+            vec.iter()
+                .map(|val| val.as_str().unwrap())
+                .collect::<Vec<_>>()
+        }) {
+            None => {
+                return Err(PostIdxError::MissingField {
+                    field: "tags".to_string(),
+                    filename: post.filename.clone(),
+                })
+            }
+            Some(val) => val,
+        };
+
+        let post_id = post.file_id;
+
+        // remove old record
+        if let Err(e) = query("DELETE FROM Tag WHERE post_id = $1")
+            .bind(post_id)
+            .execute(db_connection)
+            .await
+        {
+            return Err(PostIdxError::DBWriteFailure {
+                data_desc: "post tag information".to_string(),
+                db_table: "Tag".to_string(),
+                id: post_id.to_string(),
+                msg: e.to_string(),
+            });
+        }
+
+        // add new record
+        for tag in tags {
+            match query("INSERT INTO Tag VALUES ($1, $2);")
+                .bind(post_id)
+                .bind(tag)
+                .execute(db_connection)
+                .await
+            {
+                Ok(_) => {}
+                Err(e) => {
+                    return Err(PostIdxError::DBWriteFailure {
+                        data_desc: "post tag information".to_string(),
+                        db_table: "Tag".to_string(),
+                        id: post_id.to_string(),
+                        msg: e.to_string(),
+                    })
+                }
+            }
+        }
+    }
+
+    Ok(())
+}
+
+async fn hash(db_connection: &PgPool, post: &MdFile) -> Result<bool, PostIdxError> {
+    let base64_form = post.hash.clone();
+    match query("SELECT hash FROM Hash WHERE post_id = $1")
+        .bind(post.file_id)
+        .fetch_optional(db_connection)
+        .await
+    {
+        Ok(row) => {
+            let db_record: String = match row {
+                None => "".to_string(),
+                Some(row) => row.try_get("hash").unwrap_or("".to_string()),
+            };
+            if base64_form == db_record {
+                Ok(false)
+            } else {
+                if let Err(e) = query(
+                    r#"
+INSERT INTO Hash (post_id, hash) VALUES ($1, $2)
+    ON CONFLICT (post_id) DO UPDATE SET hash = EXCLUDED.hash"#,
+                )
+                .bind(post.file_id)
+                .bind(&base64_form)
+                .execute(db_connection)
+                .await
+                {
+                    return Err(PostIdxError::DBWriteFailure {
+                        data_desc: "post hash".to_string(),
+                        db_table: "Hash".to_string(),
+                        id: post.file_id.to_string(),
+                        msg: e.to_string(),
+                    });
+                }
+                Ok(true)
+            }
+        }
+        Err(e) => Err(PostIdxError::DBReadFailure {
+            data_desc: "post hash".to_string(),
+            db_table: "Hash".to_string(),
+            id: post.file_id.to_string(),
+            msg: e.to_string(),
+        }),
+    }
+}
+
+async fn meta(db_connection: &PgPool, post: &MdFile) -> Result<(), PostIdxError> {
+    if let Err(e) = query(
+        // todo: sanitization
+        format!(
+            r#"
+DO
+$$
+    DECLARE
+        _post_id        UUID  := '{}';
+        _meta_cols      JSONB := '{}';
+        _exists         BOOLEAN;
+        _col_name       TEXT;
+        _col_value      TEXT;
+        _sql            TEXT;
+        _insert_columns TEXT  := 'post_id';
+        _insert_values  TEXT  := quote_literal(_post_id);
+        _update_set     TEXT  := '';
+        _blacklist      TEXT[] := ARRAY['tags'];
+    BEGIN
+        SELECT EXISTS(SELECT 1 FROM meta WHERE post_id = _post_id) INTO _exists;
+
+        FOR _col_name, _col_value IN SELECT key, value FROM jsonb_each_text(_meta_cols)
+            LOOP
+                IF _col_name = ANY(_blacklist) THEN
+                    CONTINUE;
+                END IF;
+
+                IF NOT EXISTS (SELECT 1
+                               FROM information_schema.columns
+                               WHERE table_name = 'meta'
+                                 AND column_name = _col_name
+                                 -- may change in the future
+                                 AND table_schema = 'public') THEN
+                    _sql := 'ALTER TABLE meta ADD COLUMN ' || quote_ident(_col_name) || ' TEXT';
+                    EXECUTE _sql;
+                END IF;
+                _insert_columns := _insert_columns || ', ' || quote_ident(_col_name);
+                _insert_values := _insert_values || ', ' || quote_literal(_col_value);
+                _update_set := _update_set || ', ' || quote_ident(_col_name) || ' = ' || quote_literal(_col_value);
+            END LOOP;
+
+        _update_set := substring(_update_set FROM 3);
+
+        IF _exists THEN
+            _sql := 'UPDATE meta SET ' || _update_set || ' WHERE post_id = ' || quote_literal(_post_id);
+            EXECUTE _sql;
+        ELSE
+            _sql := 'INSERT INTO meta (' || _insert_columns || ') VALUES (' || _insert_values || ')';
+            EXECUTE _sql;
+        END IF;
+    END;
+$$ LANGUAGE plpgsql;
+        "#, post.file_id.to_string().as_str(), post.meta
+        ).as_str()
+    )
+        .execute(db_connection)
+        .await {
+        Err(PostIdxError::DBWriteFailure {
+            data_desc: "post meta data".to_string(),
+            db_table: "Meta".to_string(),
+            id: post.file_id.to_string(),
+            msg: e.to_string(),
+        })
+    } else {
+        Ok(())
+    }
+}
+
+pub async fn index_file(path: &Path, db_conn: &Pool<Postgres>) -> Result<(), Box<dyn Error>> {
+    let md_file = MdFile::from_file(path)?;
+
+    async fn trail(db_conn: &Pool<Postgres>, md_file: &MdFile) -> Result<(), PostIdxError> {
+        base(db_conn, md_file).await?;
+        tag(db_conn, md_file).await?;
+        meta(db_conn, md_file).await?;
+        hash(db_conn, md_file).await.map(|_| ())
+    }
+    let mut cnt = 5;
+
+    while let Err(e) = trail(db_conn, &md_file).await {
+        match e {
+            PostIdxError::DBWriteFailure { .. } => {
+                cnt -= 1;
+            }
+            PostIdxError::DBReadFailure { .. } => {
+                cnt -= 1;
+            }
+            _ => return Err(e.into()),
+        }
+        if cnt <= 0 {
+            return Err(e.into());
+        }
+    }
+
+    info!("indexed markdown file: {}", path.display());
+    Ok(())
+}
+
+pub fn drop_index(file_basename: &str, db_conn: &Pool<Postgres>) -> Result<(), Box<dyn Error>> {
+    let rt = Runtime::new().unwrap();
+    rt.block_on(async {
+        if let Err(e) = query(
+            r#"
+WITH deleted_post AS (
+    DELETE FROM post
+    WHERE id = (SELECT id FROM post WHERE filename = $1)
+    RETURNING id
+)
+DELETE FROM tag WHERE post_id IN (SELECT id FROM deleted_post);
+DELETE FROM meta WHERE post_id IN (SELECT id FROM deleted_post);
+DELETE FROM hash WHERE post_id IN (SELECT id FROM deleted_post);
+    "#,
+        )
+        .bind(file_basename)
+        .execute(db_conn)
+        .await
+        {
+            Err(Box::from(
+                format!("failed to drop index: {}", e).to_string(),
+            ))
+        } else {
+            Ok(())
+        }
+    })
+}

backend/server/src/modules/blog/cron/check_update/mod.rs

@@ -0,0 +1,148 @@
+use std::{
+    env,
+    fs::remove_dir_all,
+    path::{Path, PathBuf},
+};
+
+use crate::{
+    constants::config::general::{default_value, var_name},
+    modules::blog::cron::check_update::{
+        index::drop_index,
+        utils::{expand_path, get_md_file_basename, index_files, search_md},
+    },
+    utils::git,
+};
+use macros::panic_with_log;
+
+use git2::{Delta, Repository};
+use sqlx::{Pool, Postgres};
+use tracing::{error, info, warn, Level};
+
+mod error;
+mod index;
+mod utils;
+
+pub fn task(db_connection: &Pool<Postgres>) {
+    // init
+    let git_work_dir = {
+        let path = if let Ok(default_log_path) = env::var(var_name::WORK_DIR) {
+            expand_path(default_log_path)
+        } else {
+            let fallback_path = expand_path(default_value::WORK_DIR.to_string());
+            warn!(
+                "unset env var `{}`, using default path: {}/blog_git",
+                var_name::WORK_DIR,
+                fallback_path
+            );
+            fallback_path
+        };
+        Path::new(&path).join("blog_git")
+    };
+
+    // clone & check update
+
+    let git_url = match env::var(var_name::BLOG_GIT_URL) {
+        Ok(url) => url,
+        Err(e) => {
+            panic_with_log!(
+                Level::ERROR,
+                "failed to read `{}`: {}",
+                var_name::BLOG_GIT_URL,
+                e
+            )
+        }
+    };
+    let git_remote_name = env::var(var_name::BLOG_GIT_REMOTE_NAME)
+        .unwrap_or(default_value::BLOG_GIT_REMOTE_NAME.to_string());
+    let git_remote_branch = env::var(var_name::BLOG_GIT_REMOTE_BRANCH)
+        .unwrap_or(default_value::BLOG_GIT_REMOTE_BRANCH.to_string());
+
+    match Repository::open(&git_work_dir) {
+        Ok(repo) => {
+            // prevent git remote url mismatch (clean cache)
+            match repo.find_remote(&git_remote_name) {
+                Ok(remote) => {
+                    if remote.url().is_some_and(|url| url != git_url) {
+                        remove_dir_all(&git_work_dir).unwrap();
+                        warn!("blog content git({}) url mismatch, reinitialized", &git_url);
+                        return;
+                    }
+                }
+                Err(e) => {
+                    remove_dir_all(&git_work_dir).unwrap();
+                    error!(
+                        "unexpected error on indexing blog content git({}), reinitialized: {}",
+                        &git_url, e
+                    );
+                }
+            }
+
+            match git::sync(&git_remote_name, &git_remote_branch, &repo) {
+                Ok(updates) => {
+                    if !updates.is_empty() {
+                        // incremental update
+                        info!(
+                            "blog content git({}) update detected: {:?}",
+                            &git_url, updates
+                        );
+
+                        let mut update_md: Vec<PathBuf> = vec![];
+
+                        for update in updates {
+                            if [Delta::Deleted, Delta::Untracked].contains(&update.status) {
+                                if let Some(path) = &update.old_path {
+                                    if drop_index(
+                                        &get_md_file_basename(
+                                            path.file_name().unwrap().to_str().unwrap(),
+                                        ),
+                                        db_connection,
+                                    )
+                                    .is_ok()
+                                    {
+                                        info!(
+                                            "blog content git({}) file `{}` is detected as deleted/untracked, index dropped",
+                                            &git_url,
+                                            &path.display()
+                                        );
+                                    } else {
+                                        error!(
+                                            "blog content git({}) file `{}` is detected as deleted/untracked, failed to drop index",
+                                            &git_url,
+                                            &path.display()
+                                        )
+                                    }
+                                }
+                            } else if let Some(path) = &update.new_path {
+                                if path.components().any(|comp| comp.as_os_str() == "posts")
+                                    && path.extension().is_some_and(|ext| ext == "md")
+                                {
+                                    update_md.push(path.to_path_buf());
+                                }
+                            }
+                        }
+
+                        index_files(&update_md, db_connection);
+                    }
+                }
+                Err(e) => {
+                    error!(
+                        "failed to sync blog content git({}) updates: {}",
+                        &git_url, e
+                    );
+                }
+            }
+        }
+        Err(_) => {
+            match Repository::clone(&git_url, &git_work_dir) {
+                Ok(_repo) => {
+                    // full repo index
+                    let files = search_md(git_work_dir.join("posts"));
+                    index_files(&files, db_connection);
+                }
+                Err(e) => {
+                    error!("failed to clone blog content git({}): {}", &git_url, e);
+                }
+            }
+        }
+    };
+}

backend/server/src/modules/blog/cron/check_update/utils.rs

@@ -0,0 +1,88 @@
+use std::path::PathBuf;
+
+use crate::{
+    constants::{
+        config::general::{default_value, var_name},
+        time::DEFAULT_DATE_FORMAT,
+    },
+    modules::blog::cron::check_update::index::index_file,
+};
+
+use chrono::{DateTime, FixedOffset, ParseResult};
+use dirs::home_dir;
+use futures::{executor::block_on, future::join_all};
+use sqlx::{Pool, Postgres};
+use tokio::{runtime::Runtime, spawn};
+use tracing::{error, warn};
+
+pub fn search_md(entry: PathBuf) -> Vec<PathBuf> {
+    if entry.ends_with(".git") {
+        return vec![];
+    }
+    if entry.is_dir() {
+        if let Ok(files) = entry.read_dir() {
+            files
+                .flat_map(|file| {
+                    let file_path = file.unwrap().path();
+                    search_md(file_path)
+                })
+                .collect()
+        } else {
+            vec![]
+        }
+    } else if entry.extension().is_some_and(|ext| ext == "md") {
+        vec![entry]
+    } else {
+        vec![]
+    }
+}
+
+pub fn index_files(files: &[PathBuf], db_conn: &Pool<Postgres>) {
+    let rt = Runtime::new().unwrap();
+    rt.block_on(async {
+        let files_clone = files.to_owned();
+        let handlers = files_clone
+            .into_iter()
+            .map(|file: PathBuf| {
+                let conn_clone = db_conn.clone();
+                spawn(async move {
+                    if let Err(e) = index_file(&file, &conn_clone).await {
+                        error!("failed to index markdown file `{}`: {}", file.display(), e);
+                    }
+                })
+            })
+            .collect::<Vec<_>>();
+
+        block_on(join_all(handlers));
+    });
+}
+
+pub fn expand_path(path: String) -> String {
+    if path.starts_with('~') {
+        home_dir()
+            .map(|dir| {
+                dir.join(path.strip_prefix("~/").unwrap())
+                    .into_os_string()
+                    .into_string()
+                    .unwrap()
+            })
+            .unwrap_or_else(|| {
+                warn!(
+                    "failed to parse env var `{}`, using default value `{}`",
+                    var_name::WORK_DIR,
+                    default_value::WORK_DIR
+                );
+                default_value::WORK_DIR.to_string()
+            })
+    } else {
+        path
+    }
+}
+
+pub fn parse_date(date_str: &str) -> ParseResult<DateTime<FixedOffset>> {
+    DateTime::parse_from_str(format!("{}T120000", date_str).as_str(), DEFAULT_DATE_FORMAT)
+}
+
+pub fn get_md_file_basename(f_name: &str) -> String {
+    f_name.replace(".md", "")
+}

backend/server/src/modules/blog/cron/mod.rs

@@ -0,0 +1 @@
+// pub mod check_update;

backend/server/src/modules/blog/mod.rs

@@ -0,0 +1,52 @@
+mod api;
+mod cron;
+
+use crate::{
+    modules::{
+        blog::{
+            api::{
+                get_page_count,
+                get_post,
+                // get_post_list::get_post_list,
+            },
+            // cron::check_update,
+        },
+        Module,
+    },
+    scheduler::tasks::CronTask,
+};
+
+use axum::{routing::get, Router};
+use sqlx::PgPool;
+
+const MOUNT_POINT: &str = "/blog";
+
+pub struct Blog {
+    pub db_handler: PgPool,
+}
+
+impl Module for Blog {
+    fn get_server_router(&self) -> Router {
+        let db_handler = self.db_handler.clone();
+        // todo: move resource init to new func
+        // todo: remove debug comment
+        Router::new()
+            // .route("/get_post_list", get(get_post_list))
+            .route("/get_page_count", get(get_page_count::handler))
+            .route("/get_post/{identifier}", get(get_post::handler))
+            .with_state(db_handler)
+    }
+
+    fn get_mount_point(&self) -> &'static str {
+        MOUNT_POINT
+    }
+
+    fn get_cron_tasks(&self) -> Vec<Box<dyn CronTask>> {
+        // let db_handler = self.db_handler.clone();
+        vec![
+            // BasicTask::new(move || check_update::task(&db_handler), "0/15 * * * * *")
+            //     .unwrap()
+            //     .to_task(),
+        ]
+    }
+}

backend/server/src/modules/blog/schema.sql

@@ -0,0 +1,41 @@
+CREATE TABLE tags
+(
+    id          SERIAL PRIMARY KEY,
+    name        VARCHAR(20) UNIQUE NOT NULL,
+    description TEXT
+);
+
+CREATE TABLE categories
+(
+    id          SERIAL PRIMARY KEY,
+    name        VARCHAR(20) UNIQUE NOT NULL,
+    description TEXT
+);
+
+CREATE TABLE posts
+(
+    id             SERIAL PRIMARY KEY,
+    identifier     VARCHAR(50) UNIQUE                NOT NULL,
+    title          VARCHAR(255)                      NOT NULL,
+    subtitle       VARCHAR(255)                      NOT NULL,
+    published_date DATE                              NOT NULL,
+    last_update    DATE,
+    content        TEXT                              NOT NULL,
+
+    category       SERIAL REFERENCES categories (id) NOT NULL
+);
+
+CREATE TABLE post_tag
+(
+    post SERIAL REFERENCES posts (id),
+    tag  SERIAL REFERENCES tags (id)
+);
+
+CREATE TABLE metadata
+(
+    pid        SERIAL REFERENCES posts (id) NOT NULL,
+    meta_key   VARCHAR(50)                  NOT NULL,
+    meta_value TEXT                         NOT NULL,
+
+    CONSTRAINT meta_pk PRIMARY KEY (pid, meta_key)
+);

backend/server/src/modules/mod.rs

@@ -0,0 +1,84 @@
+pub mod blog;
+
+use std::env;
+use std::num::ParseIntError;
+
+use crate::{
+    constants::config::server::{default_value, var_name},
+    scheduler::{tasks::CronTask, Scheduler},
+};
+use macros::error_panic;
+
+use axum::Router;
+use tracing::{info, warn};
+
+// todo: merge `get_server_router` & `get_mount_point`, make Option
+pub trait Module {
+    fn get_server_router(&self) -> Router;
+
+    fn get_mount_point(&self) -> &'static str;
+
+    fn get_cron_tasks(&self) -> Vec<Box<dyn CronTask>>;
+}
+
+pub struct ModuleTree {
+    pub modules: Vec<Box<dyn Module>>,
+}
+
+impl ModuleTree {
+    pub fn new() -> Self {
+        ModuleTree { modules: vec![] }
+    }
+
+    pub fn add_module(&mut self, module: impl Module + 'static) -> &mut Self {
+        self.modules.push(Box::new(module));
+        self
+    }
+
+    pub async fn blocking_serve(&self) {
+        let scheduler = Scheduler::new();
+        let mut app = Router::new();
+
+        let port: u32 = match env::var(var_name::PORT) {
+            Ok(value) => value.parse().unwrap_or_else(|e: ParseIntError| {
+                warn!(
+                    "failed to parse `{}`, using default port: {}",
+                    var_name::PORT,
+                    e.to_string()
+                );
+                default_value::PORT
+            }),
+            Err(_) => default_value::PORT,
+        };
+
+        let listener = match tokio::net::TcpListener::bind(format!(
+            "{}:{}",
+            default_value::HOST,
+            port
+        ))
+        .await
+        {
+            Ok(listener) => {
+                info!("server started on {}:{}", default_value::HOST, port);
+                listener
+            }
+            Err(e) => {
+                error_panic!(
+                    "failed to start server on {}:{}: {}",
+                    default_value::HOST,
+                    port,
+                    e.to_string()
+                );
+            }
+        };
+
+        for module in &self.modules {
+            let _ = scheduler.insert_list(module.get_cron_tasks());
+            app = app.nest(module.get_mount_point(), module.get_server_router());
+        }
+
+        axum::serve(listener, app).await.unwrap_or_else(|e| {
+            error_panic!("failed to start axum: {}", e.to_string());
+        });
+    }
+}

backend/server/src/scheduler/mod.rs

@@ -0,0 +1,202 @@
+use std::{
+    collections::HashMap,
+    sync::{
+        atomic::{AtomicBool, Ordering},
+        Arc, RwLock,
+    },
+    thread,
+};
+
+use crate::scheduler::{
+    scheduler_error::{
+        SchedulerError, SchedulerError::IdAlreadyRunning, SchedulerError::IdNotFound,
+    },
+    sleeper::SkippableSleeper,
+    tasks::CronTask,
+};
+
+use tracing::log::error;
+use uuid::Uuid;
+
+pub mod scheduler_error;
+mod sleeper;
+mod task_func;
+pub mod tasks;
+
+struct TaskStatus {
+    sleeper: Option<Arc<SkippableSleeper>>,
+    is_alive: AtomicBool,
+}
+
+#[derive(Default)]
+pub struct Scheduler {
+    tasks: Arc<RwLock<HashMap<Uuid, Arc<Box<dyn CronTask>>>>>,
+    running: Arc<RwLock<HashMap<Uuid, Arc<TaskStatus>>>>,
+}
+
+impl Scheduler {
+    /// Start all tasks in the scheduler
+    pub fn start(&self) -> Result<(), SchedulerError> {
+        for (k, _v) in self.tasks.read()?.iter() {
+            self.run_non_blocking(k)?
+        }
+        Ok(())
+    }
+
+    /// Terminate all tasks in the scheduler
+    pub fn halt() {}
+
+    fn run_task(
+        running: Arc<RwLock<HashMap<Uuid, Arc<TaskStatus>>>>,
+        id: Uuid,
+        task: Arc<Box<dyn CronTask>>,
+    ) -> Result<(), SchedulerError> {
+        if running.read()?.get(&id).is_some() {
+            return Err(IdAlreadyRunning);
+        } else {
+            running.write()?.insert(
+                id,
+                TaskStatus {
+                    sleeper: None,
+                    is_alive: AtomicBool::new(true),
+                }
+                .into(),
+            );
+        }
+        loop {
+            if let Some(next_execution) = task.get_next_execution() {
+                // guarantee is alive
+                let task_status = {
+                    let running_reading_guard = running.read()?;
+                    running_reading_guard.get(&id).cloned().clone()
+                };
+                if let Some(task_status) = task_status {
+                    if !&task_status.is_alive.load(Ordering::SeqCst) {
+                        {
+                            let mut running_lock_guard = running.write()?;
+                            running_lock_guard.remove(&id);
+                        }
+                        return Ok(());
+                    } else {
+                        let sleeper = Arc::from(SkippableSleeper::from(next_execution));
+                        {
+                            let mut running_lock_guard = running.write()?;
+                            running_lock_guard.insert(
+                                id,
+                                TaskStatus {
+                                    sleeper: Some(sleeper.clone()),
+                                    is_alive: AtomicBool::new(true),
+                                }
+                                .into(),
+                            );
+                        }
+                        sleeper.start();
+                        task.call();
+                    }
+                }
+            } else {
+                error!("unexpected error ");
+                break;
+            }
+        }
+        Ok(())
+    }
+
+    /// Run a task with `id`
+    pub fn run(&self, id: &Uuid) -> Result<(), SchedulerError> {
+        let id = id.to_owned();
+        if let Some(task) = self.tasks.read()?.get(&id) {
+            Self::run_task(self.running.clone(), id, task.clone())
+        } else {
+            Err(IdNotFound)
+        }
+    }
+
+    pub fn run_non_blocking(&self, id: &Uuid) -> Result<(), SchedulerError> {
+        let id = id.to_owned();
+        if let Some(task) = self.tasks.read()?.get(&id) {
+            let running_clone = self.running.clone();
+            let task_clone = task.clone();
+            thread::spawn(move || Self::run_task(running_clone, id, task_clone));
+            Ok(())
+        } else {
+            Err(IdNotFound)
+        }
+    }
+
+    fn get_running(&self, id: &Uuid) -> Option<Arc<TaskStatus>> {
+        let ret = self.running.read().unwrap().get(id).cloned();
+        ret
+    }
+
+    /// Stop a task with `id`
+    pub fn stop(&self, id: &Uuid) -> Result<(), SchedulerError> {
+        match self.get_running(id) {
+            None => Err(IdNotFound),
+            Some(status) => {
+                status.is_alive.store(false, Ordering::SeqCst);
+                if let Some(s) = &status.sleeper {
+                    s.skip();
+                } else {
+                    return Err(IdAlreadyRunning);
+                }
+                Ok(())
+            }
+        }
+    }
+
+    pub fn now(&self, id: &Uuid) -> Result<(), SchedulerError> {
+        match self.get_running(id) {
+            None => Err(IdNotFound),
+            Some(status) => {
+                if let Some(s) = &status.sleeper {
+                    s.skip()
+                } else {
+                    return Err(IdAlreadyRunning);
+                }
+                Ok(())
+            }
+        }
+    }
+
+    pub fn insert(&self, task: Box<dyn CronTask>) -> Result<Uuid, SchedulerError> {
+        let id = Uuid::new_v4();
+        self.tasks.write()?.insert(id, Arc::new(task));
+        Ok(id)
+    }
+
+    pub fn insert_list(&self, tasks: Vec<Box<dyn CronTask>>) -> Result<Vec<Uuid>, SchedulerError> {
+        tasks.into_iter().map(|t| self.insert(t)).collect()
+    }
+
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::scheduler::tasks::basic::BasicTask;
+    use crate::scheduler::Scheduler;
+    use std::error::Error;
+    use std::thread;
+    use std::time::Duration;
+
+    #[test]
+    fn test_run() -> Result<(), Box<dyn Error>> {
+        let scheduler = Scheduler::default();
+        let task = BasicTask::new(|| println!("test print"), "* * * * * *")?;
+        let id = scheduler.insert(Box::new(task))?;
+        for i in 1..=2 {
+            println!("Loop {} start", i);
+            println!("Run {}", i);
+            scheduler.run_non_blocking(&id)?;
+            thread::sleep(Duration::from_secs(4));
+            scheduler.stop(&id)?;
+            println!("Stop {}", i);
+            thread::sleep(Duration::from_secs(2));
+            println!("Loop {} finished", i);
+        }
+        Ok(())
+    }
+}

backend/server/src/scheduler/scheduler_error.rs

@@ -0,0 +1,48 @@
+use std::{
+    error::Error,
+    fmt::{Debug, Display, Formatter},
+    sync::PoisonError,
+};
+
+use crate::scheduler::scheduler_error::SchedulerError::MutexPoison;
+
+// todo: refactor with thiserror
+pub enum SchedulerError {
+    IdNotFound,
+    IdAlreadyRunning,
+    MutexPoison(String),
+}
+
+impl<T> From<PoisonError<T>> for SchedulerError {
+    fn from(value: PoisonError<T>) -> Self {
+        MutexPoison(value.to_string())
+    }
+}
+
+impl Debug for SchedulerError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self)
+    }
+}
+
+impl Display for SchedulerError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{}",
+            match self {
+                SchedulerError::IdNotFound => {
+                    "SchedulerError::IdNotFound".to_string()
+                }
+                SchedulerError::IdAlreadyRunning => {
+                    "SchedulerError::IdAlreadyRunning".to_string()
+                }
+                MutexPoison(str) => {
+                    format!("SchedulerError::MutexPoison: {}", str)
+                }
+            }
+        )
+    }
+}
+
+impl Error for SchedulerError {}

backend/server/src/scheduler/sleeper.rs

@@ -0,0 +1,80 @@
+use std::{
+    sync::{Arc, Condvar, Mutex},
+    thread,
+    time::Duration,
+};
+
+use chrono::{DateTime, Utc};
+
+#[derive(Clone, Debug, Default)]
+pub struct SkippableSleeper {
+    pub duration: Duration,
+    state: Arc<(Mutex<bool>, Condvar)>,
+}
+
+impl SkippableSleeper {
+    pub fn new(duration: Duration) -> Self {
+        SkippableSleeper {
+            duration,
+            state: Arc::new((Mutex::new(false), Condvar::new())),
+        }
+    }
+
+    // Blocks until the duration has passed or skip() is called
+    pub fn start(&self) {
+        let (lock, cvar) = &*self.state;
+        let mut received = lock.lock().unwrap();
+        let state_clone = Arc::clone(&self.state);
+        let duration_clone = self.duration;
+        thread::spawn(move || {
+            thread::sleep(duration_clone);
+            let (lock, cvar) = &*state_clone;
+            let mut received = lock.lock().unwrap();
+            *received = true;
+            cvar.notify_one();
+        });
+        while !*received {
+            received = cvar.wait(received).unwrap();
+        }
+    }
+
+    // Skip the blocking delay
+    pub fn skip(&self) {
+        let (lock, cvar) = &*self.state;
+        let mut received = lock.lock().unwrap();
+        *received = true;
+        cvar.notify_one();
+    }
+}
+
+impl From<DateTime<Utc>> for SkippableSleeper {
+    fn from(value: DateTime<Utc>) -> Self {
+        let from_utc_timestamp = value.timestamp() as u64;
+        let curr_utc_timestamp = Utc::now().timestamp() as u64;
+        SkippableSleeper::new(Duration::from_secs(from_utc_timestamp - curr_utc_timestamp))
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::scheduler::sleeper::SkippableSleeper;
+    use std::thread;
+    use std::time::Duration;
+
+    #[test]
+    fn usage() {
+        let sleeper = SkippableSleeper::new(Duration::new(10, 0));
+        thread::spawn({
+            let sleeper = sleeper.clone();
+            move || {
+                println!("Sleeping...");
+                sleeper.start();
+                println!("Woke up!");
+            }
+        });
+        println!("Start Sleeping...");
+        thread::sleep(Duration::from_secs(4));
+        println!("Skipping sleep...");
+        sleeper.skip();
+    }
+}

backend/server/src/scheduler/task_func.rs

@@ -0,0 +1,3 @@
+pub trait TaskFunc: Fn() + Send + Sync + 'static {}
+
+impl<T> TaskFunc for T where T: Fn() + Send + Sync + Clone + 'static {}

backend/server/src/scheduler/tasks/basic.rs

@@ -0,0 +1,38 @@
+use std::error::Error;
+use std::str::FromStr;
+
+use crate::scheduler::{task_func::TaskFunc, tasks::CronTask};
+
+use chrono::{DateTime, Utc};
+use cron::Schedule;
+
+pub struct BasicTask {
+    schedule: Schedule,
+    func: Box<dyn TaskFunc>,
+}
+
+impl BasicTask {
+    pub fn new<F>(func: F, cron_expr: &str) -> Result<Self, Box<dyn Error>>
+    where
+        F: TaskFunc,
+    {
+        Ok(BasicTask {
+            schedule: Schedule::from_str(cron_expr)?,
+            func: Box::new(func),
+        })
+    }
+
+    pub fn to_task(self) -> Box<dyn CronTask> {
+        Box::new(self)
+    }
+}
+
+impl CronTask for BasicTask {
+    fn get_next_execution(&self) -> Option<DateTime<Utc>> {
+        self.schedule.upcoming(Utc).next()
+    }
+
+    fn call(&self) {
+        (self.func)()
+    }
+}

backend/server/src/scheduler/tasks/mod.rs

@@ -0,0 +1,8 @@
+use chrono::{DateTime, Utc};
+
+pub mod basic;
+
+pub trait CronTask: Send + Sync {
+    fn get_next_execution(&self) -> Option<DateTime<Utc>>;
+    fn call(&self);
+}

backend/server/src/utils/git.rs

@@ -0,0 +1,166 @@
+/// git merge
+/// based on https://github.com/rust-lang/git2-rs/blob/master/examples/pull.rs
+/// https://github.com/rust-lang/git2-rs/commit/f3b87baed1e33d6c2d94fe1fa6aa6503a071d837
+///
+use git2::{
+    build, AnnotatedCommit, AutotagOption, Delta, FetchOptions, Reference, Remote, Repository,
+};
+use std::path::PathBuf;
+use tracing::{error, warn};
+
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct FileDelta {
+    pub old_path: Option<PathBuf>,
+    pub new_path: Option<PathBuf>,
+    pub status: Delta,
+}
+
+#[allow(dead_code)]
+fn do_fetch<'a>(
+    repo: &'a Repository,
+    refs: &[&str],
+    remote: &'a mut Remote,
+) -> Result<AnnotatedCommit<'a>, git2::Error> {
+    let mut fetch_option = FetchOptions::new();
+
+    fetch_option.download_tags(AutotagOption::All);
+    remote.fetch(refs, Some(&mut fetch_option), None)?;
+
+    let fetch_head = repo.find_reference("FETCH_HEAD")?;
+    repo.reference_to_annotated_commit(&fetch_head)
+}
+
+#[allow(dead_code)]
+fn fast_forward(
+    repo: &Repository,
+    lb: &mut Reference,
+    rc: &AnnotatedCommit,
+) -> Result<(), git2::Error> {
+    let name = match lb.name() {
+        Some(s) => s.to_string(),
+        None => String::from_utf8_lossy(lb.name_bytes()).to_string(),
+    };
+    let msg = format!("fast-forward({}) -> {}", name, rc.id());
+    // println!("{}", msg);
+    lb.set_target(rc.id(), &msg)?;
+    repo.set_head(&name)?;
+    repo.checkout_head(Some(build::CheckoutBuilder::default().force()))?;
+    Ok(())
+}
+
+#[allow(dead_code)]
+fn normal_merge(
+    repo: &Repository,
+    local: &AnnotatedCommit,
+    remote: &AnnotatedCommit,
+) -> Result<(), git2::Error> {
+    let local_tree = repo.find_commit(local.id())?.tree()?;
+    let remote_tree = repo.find_commit(remote.id())?.tree()?;
+    let ancestor = repo
+        .find_commit(repo.merge_base(local.id(), remote.id())?)?
+        .tree()?;
+    let mut idx = repo.merge_trees(&ancestor, &local_tree, &remote_tree, None)?;
+
+    if idx.has_conflicts() {
+        warn!("merge conflicts detected");
+        repo.checkout_index(Some(&mut idx), None)?;
+        return Ok(());
+    }
+    let result_tree = repo.find_tree(idx.write_tree_to(repo)?)?;
+
+    let msg = format!("merge({}) -> {}", remote.id(), local.id());
+    let sig = repo.signature()?;
+    let local_commit = repo.find_commit(local.id())?;
+    let remote_commit = repo.find_commit(remote.id())?;
+
+    let _merge_commit = repo.commit(
+        Some("HEAD"),
+        &sig,
+        &sig,
+        &msg,
+        &result_tree,
+        &[&local_commit, &remote_commit],
+    )?;
+    repo.checkout_head(None)?;
+    Ok(())
+}
+
+#[allow(dead_code)]
+fn do_merge<'a>(
+    repo: &'a Repository,
+    remote_branch: &str,
+    fetch_commit: AnnotatedCommit<'a>,
+) -> Result<Vec<FileDelta>, git2::Error> {
+    let analysis = repo.merge_analysis(&[&fetch_commit])?;
+    let head_commit = repo.reference_to_annotated_commit(&repo.head()?)?;
+
+    if analysis.0.is_fast_forward() {
+        let ref_name = format!("refs/heads/{}", remote_branch);
+        match repo.find_reference(&ref_name) {
+            Ok(mut r) => {
+                fast_forward(repo, &mut r, &fetch_commit)?;
+            }
+            Err(_) => {
+                repo.reference(
+                    &ref_name,
+                    fetch_commit.id(),
+                    true,
+                    &format!("({}) -> {}", remote_branch, fetch_commit.id()),
+                )?;
+                repo.set_head(&ref_name)?;
+                repo.checkout_head(Some(
+                    build::CheckoutBuilder::default()
+                        .allow_conflicts(true)
+                        .conflict_style_merge(true)
+                        .force(),
+                ))?;
+            }
+        };
+    } else if analysis.0.is_normal() {
+        normal_merge(repo, &head_commit, &fetch_commit)?;
+    }
+    calculate_diff(repo, &head_commit, &fetch_commit)
+}
+
+#[allow(dead_code)]
+fn calculate_diff(
+    repo: &Repository,
+    local: &AnnotatedCommit,
+    remote: &AnnotatedCommit,
+) -> Result<Vec<FileDelta>, git2::Error> {
+    let local_tree = repo.find_commit(local.id())?.tree()?;
+    let remote_tree = repo.find_commit(remote.id())?.tree()?;
+    let diff = repo.diff_tree_to_tree(Some(&local_tree), Some(&remote_tree), None)?;
+
+    let mut updated_files: Vec<FileDelta> = Vec::new();
+
+    if let Err(e) = diff.foreach(
+        &mut |d, _| {
+            updated_files.push(FileDelta {
+                old_path: d.old_file().path().map(PathBuf::from),
+                new_path: d.new_file().path().map(PathBuf::from),
+                status: d.status(),
+            });
+            true
+        },
+        None,
+        None,
+        None,
+    ) {
+        error!("error at calculating diff: {:?}", e);
+    }
+
+    Ok(updated_files.into_iter().collect())
+}
+
+#[allow(dead_code)]
+pub fn sync(
+    remote_name: &str,
+    remote_branch: &str,
+    repo: &Repository,
+) -> Result<Vec<FileDelta>, git2::Error> {
+    let mut remote = repo.find_remote(remote_name)?;
+    let fetch_commit = do_fetch(repo, &[remote_branch], &mut remote)?;
+    do_merge(repo, remote_branch, fetch_commit)
+}

backend/server/src/utils/mod.rs

@@ -0,0 +1 @@
+pub mod git;

gateway/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "loadbalancer"
+name = "gateway"
 version = "0.1.0"
 edition = "2021"