feat: set up basic database migration

.gitignore

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+/target

Cargo.toml

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+[package]
+name = "calathea"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+axum = "0.7.9"
+chrono = "0.4.39"
+r2d2 = "0.8.10"
+r2d2_sqlite = "0.25.0"
+tokio = { version = "1.42.0", features = ["full"] }

src/main.rs

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+use r2d2_sqlite::{rusqlite, SqliteConnectionManager};
+
+pub type DbPool = r2d2::Pool<SqliteConnectionManager>;
+
+const MIGRATIONS: [&str; 1] = [include_str!("migrations/000_initial.sql")];
+
+#[tokio::main]
+async fn main() {
+    let manager = SqliteConnectionManager::file("db.sqlite");
+    let pool = r2d2::Pool::new(manager).unwrap();
+    run_migrations(&pool, true).unwrap();
+}
+
+fn run_migrations(pool: &DbPool, new: bool) -> rusqlite::Result<()> {
+    let mut conn = pool.get().unwrap();
+
+    // Run very first migration
+    if new {
+        let tx = conn.transaction()?;
+
+        tx.execute(MIGRATIONS[0], ())?;
+
+        let cur_time = chrono::Local::now().timestamp();
+        tx.execute(
+            "insert into migration_version values ($1, $2)",
+            [0, cur_time],
+        )?;
+
+        tx.commit()?;
+    }
+
+    let mut next_version = conn.query_row(
+        "select version from migration_version order by updated_at desc limit 1",
+        (),
+        |row| row.get::<_, usize>(0),
+    )? + 1;
+
+    while next_version < MIGRATIONS.len() {
+        let tx = conn.transaction()?;
+
+        tx.execute(MIGRATIONS[next_version], ())?;
+
+        let cur_time = chrono::Local::now().timestamp();
+        tx.execute(
+            "insert into migration_version values ($1, $2)",
+            (next_version, cur_time),
+        )?;
+
+        tx.commit()?;
+
+        next_version += 1;
+    }
+
+    Ok(())
+}

src/migrations/000_initial.sql

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+create table migration_version (
+    version integer,
+    updated_at integer
+);