#!/usr/bin/env python3
"""Apply pending SQL migrations and record them in schema_versions.

Usage:
    python migrations.py

Connects to PostgreSQL using the same environment variables as the API:
    POSTGRES_DB       (default: sba_master)
    POSTGRES_USER     (default: sba_admin)
    POSTGRES_PASSWORD (required)
    POSTGRES_HOST     (default: sba_postgres)
    POSTGRES_PORT     (default: 5432)

On first run against an existing database, all migrations will be applied.
All migration files use IF NOT EXISTS guards so re-applying is safe.
"""

import os
import sys
from pathlib import Path

import psycopg2


MIGRATIONS_DIR = Path(__file__).parent / "migrations"

_CREATE_SCHEMA_VERSIONS = """
CREATE TABLE IF NOT EXISTS schema_versions (
    filename VARCHAR(255) PRIMARY KEY,
    applied_at TIMESTAMP NOT NULL DEFAULT NOW()
);
"""


def _get_connection():
    password = os.environ.get("POSTGRES_PASSWORD")
    if password is None:
        raise RuntimeError("POSTGRES_PASSWORD environment variable is not set")
    return psycopg2.connect(
        dbname=os.environ.get("POSTGRES_DB", "sba_master"),
        user=os.environ.get("POSTGRES_USER", "sba_admin"),
        password=password,
        host=os.environ.get("POSTGRES_HOST", "sba_postgres"),
        port=int(os.environ.get("POSTGRES_PORT", "5432")),
    )


def main():
    conn = _get_connection()
    try:
        with conn:
            with conn.cursor() as cur:
                cur.execute(_CREATE_SCHEMA_VERSIONS)

        with conn.cursor() as cur:
            cur.execute("SELECT filename FROM schema_versions")
            applied = {row[0] for row in cur.fetchall()}

        migration_files = sorted(MIGRATIONS_DIR.glob("*.sql"))
        pending = [f for f in migration_files if f.name not in applied]

        if not pending:
            print("No pending migrations.")
            return

        for migration_file in pending:
            print(f"Applying {migration_file.name} ...", end=" ", flush=True)
            sql = migration_file.read_text()
            with conn:
                with conn.cursor() as cur:
                    cur.execute(sql)
                    cur.execute(
                        "INSERT INTO schema_versions (filename) VALUES (%s)",
                        (migration_file.name,),
                    )
            print("done")

        print(f"\nApplied {len(pending)} migration(s).")
    finally:
        conn.close()


if __name__ == "__main__":
    try:
        main()
    except Exception as e:
        print(f"Error: {e}", file=sys.stderr)
        sys.exit(1)