use rusqlite::{params, Connection};

pub fn init_db(conn: &Connection) {
    conn.execute(
        "CREATE TABLE IF NOT EXISTS users (
            username TEXT PRIMARY KEY,
            hashed_password TEXT NOT NULL,
            account_id INTEGER UNIQUE,
            balance INTEGER DEFAULT 1000
        )",
        [],
    )
    .unwrap();
    // Add column if not exists (for migration)
    let _ = conn.execute("ALTER TABLE users ADD COLUMN account_id INTEGER UNIQUE", []);
    let _ = conn.execute(
        "ALTER TABLE users ADD COLUMN balance INTEGER DEFAULT 1000",
        [],
    );
    conn.execute(
        "CREATE TABLE IF NOT EXISTS plays (
            session_id TEXT PRIMARY KEY,
            username TEXT NOT NULL,
            game_type TEXT NOT NULL,
            bet_amount INTEGER NOT NULL,
            winnings INTEGER NOT NULL,
            balance_after INTEGER NOT NULL,
            details TEXT NOT NULL DEFAULT '{}',
            created_at DATETIME DEFAULT CURRENT_TIMESTAMP
        )",
        [],
    )
    .unwrap();
}

pub fn add_user(
    conn: &Connection,
    username: &str,
    hashed_password: &str,
) -> Result<(), Box<dyn std::error::Error>> {
    if get_hashed_password(conn, username).is_some() {
        return Err("user already exists".into());
    }

    for _ in 0..10 {
        let account_id: u32 = rand::random::<u32>();
        match conn.execute(
            "INSERT INTO users (username, hashed_password, account_id, balance)
             VALUES (?1, ?2, ?3, ?4)",
            params![username, hashed_password, account_id as i64, 1000i64],
        ) {
            Ok(_) => return Ok(()),
            Err(rusqlite::Error::SqliteFailure(error, _))
                if error.code == rusqlite::ErrorCode::ConstraintViolation =>
            {
                continue;
            }
            Err(error) => return Err(Box::new(error)),
        }
    }

    Err("could not allocate a unique account id".into())
}

pub fn get_hashed_password(conn: &Connection, username: &str) -> Option<String> {
    let mut stmt = conn
        .prepare("SELECT hashed_password FROM users WHERE username = ?1")
        .unwrap();
    let mut rows = stmt.query([username]).unwrap();
    if let Ok(Some(row)) = rows.next() {
        row.get(0).ok()
    } else {
        None
    }
}

pub fn set_hashed_password(
    conn: &Connection,
    username: &str,
    hashed_password: &str,
) -> rusqlite::Result<()> {
    conn.execute(
        "UPDATE users SET hashed_password = ?1 WHERE username = ?2",
        params![hashed_password, username],
    )?;
    Ok(())
}

pub fn get_account_id(conn: &Connection, username: &str) -> Option<i64> {
    let mut stmt = conn
        .prepare("SELECT account_id FROM users WHERE username = ?1")
        .unwrap();
    let mut rows = stmt.query([username]).unwrap();
    if let Ok(Some(row)) = rows.next() {
        Some(row.get::<_, i64>(0).ok()?)
    } else {
        None
    }
}

pub fn get_balance(conn: &Connection, username: &str) -> Option<i64> {
    let mut stmt = conn
        .prepare("SELECT balance FROM users WHERE username = ?1")
        .unwrap();
    let mut rows = stmt.query([username]).unwrap();
    if let Ok(Some(row)) = rows.next() {
        Some(row.get::<_, i64>(0).ok()?)
    } else {
        None
    }
}

/// Settle one play and record its audit row in a single transaction.
///
/// `details` is a JSON object with game-specific fields (reels, cards,
/// winning number, crash point, ...). All SQL is parameterized: usernames are
/// data, never part of the statement text.
///
/// Returns the balance after the play.
#[allow(clippy::too_many_arguments)]
pub fn apply_play(
    conn: &mut Connection,
    session_id: &str,
    username: &str,
    game_type: &str,
    bet_amount: i64,
    winnings: i64,
    details: &str,
) -> rusqlite::Result<i64> {
    let tx = conn.transaction()?;

    let deducted = tx.execute(
        "UPDATE users SET balance = balance - ?1
         WHERE username = ?2 AND balance >= ?1",
        params![bet_amount, username],
    )?;
    if deducted != 1 {
        return Err(rusqlite::Error::QueryReturnedNoRows);
    }

    tx.execute(
        "UPDATE users SET balance = balance + ?1 WHERE username = ?2",
        params![winnings, username],
    )?;

    let balance_after: i64 = tx.query_row(
        "SELECT balance FROM users WHERE username = ?1",
        [username],
        |row| row.get(0),
    )?;

    tx.execute(
        "INSERT INTO plays
            (session_id, username, game_type, bet_amount, winnings,
             balance_after, details)
         VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7)",
        params![
            session_id,
            username,
            game_type,
            bet_amount,
            winnings,
            balance_after,
            details
        ],
    )?;

    tx.commit()?;
    Ok(balance_after)
}

pub fn count_plays(conn: &Connection, username: &str) -> i64 {
    conn.query_row(
        "SELECT COUNT(*) FROM plays WHERE username = ?1",
        [username],
        |row| row.get(0),
    )
    .unwrap_or(0)
}