import sqlite3
from pathlib import Path
from typing import Optional

from backend.config import DATABASE_PATH


def get_connection() -> sqlite3.Connection:
    conn = sqlite3.connect(DATABASE_PATH)
    conn.row_factory = sqlite3.Row
    return conn


def init_db() -> None:
    Path(DATABASE_PATH).parent.mkdir(parents=True, exist_ok=True)
    conn = get_connection()
    try:
        conn.executescript("""
        CREATE TABLE IF NOT EXISTS banks (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            code TEXT NOT NULL UNIQUE,
            name TEXT NOT NULL,
            is_salary INTEGER NOT NULL DEFAULT 0
        );

        CREATE TABLE IF NOT EXISTS accounts (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            bank_id INTEGER NOT NULL REFERENCES banks(id),
            external_id TEXT NOT NULL,
            name TEXT,
            UNIQUE(bank_id, external_id)
        );

        CREATE TABLE IF NOT EXISTS opening_balances (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            account_id INTEGER NOT NULL REFERENCES accounts(id),
            period_start TEXT NOT NULL,
            amount REAL NOT NULL,
            UNIQUE(account_id, period_start)
        );

        CREATE TABLE IF NOT EXISTS transactions (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            account_id INTEGER NOT NULL REFERENCES accounts(id),
            operation_date TEXT NOT NULL,
            debit_date TEXT,
            amount REAL NOT NULL,
            currency TEXT DEFAULT 'RUB',
            amount_card_currency REAL,
            description TEXT,
            source_file TEXT NOT NULL,
            imported_at TEXT NOT NULL,
            dedup_key TEXT NOT NULL UNIQUE
        );

        CREATE INDEX IF NOT EXISTS idx_transactions_account ON transactions(account_id);
        CREATE INDEX IF NOT EXISTS idx_transactions_operation_date ON transactions(operation_date);
        CREATE INDEX IF NOT EXISTS idx_transactions_dedup ON transactions(dedup_key);
        """)
        conn.commit()
        try:
            conn.execute("ALTER TABLE transactions ADD COLUMN excluded_from_balance INTEGER NOT NULL DEFAULT 0")
            conn.commit()
        except sqlite3.OperationalError:
            pass
        conn.executescript("""
        CREATE TABLE IF NOT EXISTS app_settings (
            key TEXT PRIMARY KEY,
            value TEXT
        );
        """)
        conn.commit()
    finally:
        conn.close()