use sqlx::{sqlite::SqlitePoolOptions, SqlitePool};

pub async fn init() -> Result<SqlitePool, sqlx::Error> {
    let url = std::env::var("DATABASE_URL")
        .unwrap_or_else(|_| "sqlite:/data/attendance.db".into());
    let pool = SqlitePoolOptions::new()
        .after_connect(|conn, _| Box::pin(async move {
            sqlx::query("PRAGMA foreign_keys = ON")
                .execute(conn).await?;
            Ok(())
        }))
        .connect(&url).await?;
    sqlx::migrate!("./migrations").run(&pool).await?;
    Ok(pool)
}

#[cfg(test)]
mod tests {
    use super::*;

    // NOTE: #[sqlx::test] injects its own pool, bypassing after_connect.
    // We test FK enforcement behaviorally: insert a row with a bad FK and assert it fails.
    // The PRAGMA is manually issued at the top of this test body.
    #[sqlx::test(migrations = "./migrations")]
    async fn foreign_keys_enforced(pool: SqlitePool) {
        // Enable FK for this test connection (mirrors what after_connect does in production)
        sqlx::query("PRAGMA foreign_keys = ON").execute(&pool).await.unwrap();

        let err = sqlx::query(
            "INSERT INTO students (course_id, name) VALUES (999, 'Ghost')"
        ).execute(&pool).await;
        assert!(err.is_err(), "FK violation should be rejected when foreign_keys = ON");
    }

    #[sqlx::test(migrations = "./migrations")]
    async fn all_tables_exist(pool: SqlitePool) {
        for table in &["courses","tutors","tutor_courses","students","rooms",
                       "sessions","slots","attendances","notes"] {
            let count: (i64,) = sqlx::query_as(
                "SELECT count(*) FROM sqlite_master WHERE type='table' AND name=?"
            ).bind(table).fetch_one(&pool).await.unwrap();
            assert_eq!(count.0, 1, "table {table} missing");
        }
    }
}