import sqlite3
from typing import Iterable

from app.config import DB_NAME


DEFAULT_CATEGORIES: Iterable[tuple[str, str]] = [
    ("Продукты", "Расход"),
    ("Транспорт", "Расход"),
    ("Кафе", "Расход"),
    ("Жильё", "Расход"),
    ("Здоровье", "Расход"),
    ("Развлечения", "Расход"),
    ("Одежда", "Расход"),
    ("Образование", "Расход"),
    ("Коммунальные услуги", "Расход"),
    ("Связь и интернет", "Расход"),
    ("Зарплата", "Доход"),
    ("Фриланс", "Доход"),
    ("Подарки", "Доход"),
    ("Возврат", "Доход"),
    ("Проценты по вкладу", "Доход"),
]


def get_connection() -> sqlite3.Connection:
    """Open SQLite connection with row access by column name."""
    connection = sqlite3.connect(DB_NAME)
    connection.row_factory = sqlite3.Row
    connection.execute("PRAGMA foreign_keys = ON")
    return connection


def init_database() -> None:
    """Create all tables, indexes and default records."""
    with get_connection() as connection:
        cursor = connection.cursor()
        cursor.executescript(
            """
            CREATE TABLE IF NOT EXISTS accounts (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                name TEXT NOT NULL,
                account_type TEXT NOT NULL,
                balance REAL NOT NULL DEFAULT 0,
                created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
            );

            CREATE TABLE IF NOT EXISTS categories (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                name TEXT NOT NULL,
                category_type TEXT NOT NULL,
                created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
                UNIQUE(name, category_type)
            );

            CREATE TABLE IF NOT EXISTS transactions (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                title TEXT NOT NULL,
                amount REAL NOT NULL,
                transaction_type TEXT NOT NULL,
                account_id INTEGER NOT NULL,
                category_id INTEGER NOT NULL,
                created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
                FOREIGN KEY (account_id)
                    REFERENCES accounts(id) ON DELETE RESTRICT,
                FOREIGN KEY (category_id)
                    REFERENCES categories(id) ON DELETE RESTRICT
            );

            CREATE TABLE IF NOT EXISTS subscriptions (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                name TEXT NOT NULL,
                amount REAL NOT NULL,
                billing_day INTEGER NOT NULL,
                period TEXT NOT NULL,
                status TEXT NOT NULL DEFAULT 'Активна',
                created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
            );

            CREATE TABLE IF NOT EXISTS budgets (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                category_id INTEGER NOT NULL UNIQUE,
                limit_amount REAL NOT NULL,
                created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
                FOREIGN KEY (category_id)
                    REFERENCES categories(id) ON DELETE RESTRICT
            );

            CREATE TABLE IF NOT EXISTS settings (
                key TEXT PRIMARY KEY,
                value TEXT NOT NULL
            );

            CREATE INDEX IF NOT EXISTS idx_transactions_created_at
                ON transactions(created_at);
            CREATE INDEX IF NOT EXISTS idx_transactions_type
                ON transactions(transaction_type);
            CREATE INDEX IF NOT EXISTS idx_transactions_account
                ON transactions(account_id);
            CREATE INDEX IF NOT EXISTS idx_transactions_category
                ON transactions(category_id);
            """
        )
        _ensure_column(cursor, "accounts", "created_at", "TEXT")
        _ensure_column(cursor, "categories", "created_at", "TEXT")
        _ensure_column(cursor, "subscriptions", "created_at", "TEXT")
        _ensure_column(cursor, "budgets", "created_at", "TEXT")
        cursor.executemany(
            """
            INSERT OR IGNORE INTO categories (name, category_type)
            VALUES (?, ?)
            """,
            DEFAULT_CATEGORIES,
        )
        connection.commit()


def _ensure_column(cursor: sqlite3.Cursor, table: str, column: str, column_type: str) -> None:
    """Add a column when an old alpha database is opened."""
    columns = [row[1] for row in cursor.execute(f"PRAGMA table_info({table})")]
    if column not in columns:
        cursor.execute(f"ALTER TABLE {table} ADD COLUMN {column} {column_type}")
        cursor.execute(
            f"UPDATE {table} SET {column} = CURRENT_TIMESTAMP "
            f"WHERE {column} IS NULL"
        )