use std::{env, error::Error, sync::LazyLock};

use rusqlite::{Connection, OptionalExtension};

macro_rules! migration {
    ($name:literal) => {
        ($name, include_str!(concat!("./migrations/", $name, ".sql")))
    };
}
const MIGRATIONS: &[(&str, &str)] = &[migration!("2026-02-20--01")];

pub static DB_URL: LazyLock<String> =
    LazyLock::new(|| env::var("DATABASE_URL").expect("DATABASE_URL is not set"));

const PERSISTENT_PRAGMAS: &[&str] = &["PRAGMA journal_mode = WAL"];
const CONNECTION_PRAGMAS: &[&str] = &["PRAGMA foreign_keys = ON", "PRAGMA busy_timeout = 5000"];
const TABLE_MIGRATIONS: &str = r#"
CREATE TABLE IF NOT EXISTS migrations (
    id      TEXT    PRIMARY KEY,
    time    INTEGER DEFAULT (unixepoch())
);
"#;

pub fn conn() -> Result<Connection, rusqlite::Error> {
    let conn = Connection::open(&*DB_URL)?;
    for pragma in CONNECTION_PRAGMAS {
        conn.query_row(*pragma, (), |_| Ok(())).optional()?;
    }
    Ok(conn)
}

pub fn migrations() -> Result<(), Box<dyn Error>> {
    let conn = Connection::open(&*DB_URL)?;
    for pragma in PERSISTENT_PRAGMAS {
        conn.query_row(*pragma, (), |_| Ok(()))?;
    }
    conn.execute(TABLE_MIGRATIONS, ())?;

    let mut changes = false;
    for (key, sql) in MIGRATIONS {
        let mut statement = conn.prepare("SELECT id, time FROM migrations WHERE id = ?1")?;
        let query = statement.query_one([key], |_| Ok(())).optional()?;
        if query.is_some() {
            continue;
        }
        changes = true;
        println!("Applying migration {key}...");

        conn.execute_batch(sql)?;
        conn.execute("INSERT INTO migrations(id) VALUES (?1)", &[key])?;
    }

    if changes {
        println!("Migrations applied.")
    }
    Ok(())
}