#!/usr/bin/env python3
"""
Migrate MariaDB export to SQLite for qaffee.

Usage:
    python3 db/migrate_to_sqlite.py

Creates data/qaffee.db ready for use with the Quarkus backend.
Flyway will baseline at V4 on first startup (no re-migration needed).
"""

import re
import sqlite3
import os
import sys

SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
REPO_ROOT   = os.path.join(SCRIPT_DIR, '..')
MIGRATION_DIR = os.path.join(REPO_ROOT, 'backend', 'src', 'main', 'resources', 'db', 'migration')
EXPORT_FILE = os.path.join(SCRIPT_DIR, 'mariadb_export.sql')
OUTPUT_FILE = os.path.join(REPO_ROOT, 'data', 'qaffee.db')

# V2 (seed data) is intentionally skipped – it inserts dev/test rows that
# conflict with production IDs in the export.
MIGRATIONS = [
    'V1__initial_schema.sql',
    'V3__company_logo.sql',
    'V4__tally_price_at_booking.sql',
]

# Tables to import in FK-safe order (parents before children)
DATA_TABLES = ['company', 'employee', 'product', 'access_link', 'tally_entry']


def apply_migrations(conn: sqlite3.Connection) -> None:
    for filename in MIGRATIONS:
        path = os.path.join(MIGRATION_DIR, filename)
        with open(path, 'r', encoding='utf-8') as f:
            sql = f.read()
        conn.executescript(sql)
        print(f'  schema  {filename}')


def mariadb_to_sqlite_sql(sql: str) -> str:
    # Remove MariaDB sandbox-mode comment at the top
    sql = re.sub(r'/\*M!.*?\*/', '', sql, flags=re.DOTALL)
    # Strip backtick identifier quotes
    sql = sql.replace('`', '')
    # Convert 0xABCD hex literals to SQLite X'ABCD' blob literals
    sql = re.sub(r'\b0x([0-9A-Fa-f]+)', r"X'\1'", sql)
    return sql


def extract_insert(sql: str, table: str) -> str | None:
    """Return the full INSERT INTO <table> VALUES ...; statement, or None."""
    pattern = rf'(INSERT INTO {re.escape(table)} VALUES\s*.*?;)'
    match = re.search(pattern, sql, re.DOTALL)
    return match.group(1) if match else None


def main() -> None:
    os.makedirs(os.path.dirname(OUTPUT_FILE), exist_ok=True)

    if os.path.exists(OUTPUT_FILE):
        os.remove(OUTPUT_FILE)
        print(f'Removed existing {OUTPUT_FILE}')

    print('Reading MariaDB export ...')
    with open(EXPORT_FILE, 'r', encoding='utf-8') as f:
        raw_sql = f.read()

    sqlite_sql = mariadb_to_sqlite_sql(raw_sql)

    print('Creating SQLite database ...')
    conn = sqlite3.connect(OUTPUT_FILE)

    print('Applying schema migrations:')
    apply_migrations(conn)

    print('Importing data:')
    for table in DATA_TABLES:
        stmt = extract_insert(sqlite_sql, table)
        if stmt is None:
            print(f'  skip    {table} (no data in export)')
            continue
        conn.executescript(stmt)
        # Count rows for feedback
        count = conn.execute(f'SELECT COUNT(*) FROM {table}').fetchone()[0]
        print(f'  import  {table} ({count} rows)')

    conn.commit()
    conn.close()

    size_kb = os.path.getsize(OUTPUT_FILE) // 1024
    print(f'\nDone – {OUTPUT_FILE} ({size_kb} KB)')
    print()
    print('Next steps:')
    print('  1. docker compose up --build')
    print('     Flyway will baseline at V4 and skip all migrations.')
    print('  2. Verify at https://qaffee.cloud.aquantico.de')


if __name__ == '__main__':
    main()