#!/usr/bin/env python3
"""
Shinkan Jinkendo — Datenbank-Migrationen

**Idempotent** über `schema_migrations`: jede numerische Datei `migrations/*.sql` höchstens einmal
als „erfolgreich“ eingetragen; bei erneutem Start werden nur noch fehlende Dateien abgearbeitet.

**Reihenfolge:** Alle `NNN_*.sql` nach führender Zahl (001 vor 009 vor 010 …), bei gleicher Zahl
alphabetisch nach Dateinamen — nicht bloß String-Sortierung (vermeidet z. B. `10_` vor `9_`).

**Pro Datei eine Transaktion:** Entweder `psql -1 -f` (wie bei psql/pg_dump üblich) oder Fallback
über `sqlparse.split` und einzelne `cursor.execute` in einer DB-Transaktion.

Nach erfolgreicher Ausführung: `INSERT INTO schema_migrations (migration)` (mit `ON CONFLICT DO NOTHING`).
"""
import os
import re
import shutil
import subprocess
import sys
import time
from typing import List, Tuple

import psycopg2
import sqlparse


def _db_params():
    return {
        "host": os.getenv("DB_HOST", "localhost"),
        "port": os.getenv("DB_PORT", "5432"),
        "dbname": os.getenv("DB_NAME", "shinkan_dev"),
        "user": os.getenv("DB_USER", "shinkan_dev"),
        "password": os.getenv("DB_PASSWORD", "dev_password"),
    }


def get_db_connection():
    """PostgreSQL-Verbindung mit Retry (Container-Start)."""
    p = _db_params()
    max_retries = 30
    for i in range(max_retries):
        try:
            conn = psycopg2.connect(
                host=p["host"],
                port=p["port"],
                database=p["dbname"],
                user=p["user"],
                password=p["password"],
            )
            conn.autocommit = False
            print(f"[OK] Connected to database: {p['dbname']}")
            return conn
        except psycopg2.OperationalError:
            if i < max_retries - 1:
                print(f"Waiting for database... ({i+1}/{max_retries})")
                time.sleep(2)
            else:
                print(f"[FAIL] Failed to connect to database after {max_retries} attempts")
                raise


def init_migrations_table(conn):
    with conn.cursor() as cur:
        cur.execute(
            """
            CREATE TABLE IF NOT EXISTS schema_migrations (
                id SERIAL PRIMARY KEY,
                migration VARCHAR(255) UNIQUE NOT NULL,
                executed_at TIMESTAMP DEFAULT NOW()
            )
            """
        )
    conn.commit()
    print("[OK] schema_migrations initialisiert")


_LEADING_DIGITS = re.compile(r"^(\d+)")


def _migration_sort_key_from_stem(stem: str) -> Tuple[int, str]:
    """Sortierung: numerisches Präfix am Anfang des Stems, dann voller Stem (stabil)."""
    m = _LEADING_DIGITS.match(stem)
    n = int(m.group(1)) if m else 0
    return (n, stem)


def get_migration_files_ordered(migrations_dir: str) -> List[Tuple[str, str]]:
    rows = []
    for filename in os.listdir(migrations_dir):
        if not filename.endswith(".sql"):
            continue
        if not filename[0].isdigit():
            continue
        stem = filename[:-4]
        rows.append((stem, os.path.join(migrations_dir, filename)))
    rows.sort(key=lambda item: _migration_sort_key_from_stem(item[0]))
    return rows


def get_executed(conn) -> set:
    with conn.cursor() as cur:
        cur.execute("SELECT migration FROM schema_migrations")
        return set(r[0] for r in cur.fetchall())


def get_pending(conn, migrations_dir: str):
    executed = get_executed(conn)
    pending = []
    for name, path in get_migration_files_ordered(migrations_dir):
        if name not in executed:
            pending.append((name, path))
    return pending


def _split_statements(sql_text: str) -> List[str]:
    """Fallback ohne psql — einzelne Statements (sqlparse.split)."""
    stripped = sql_text.strip()
    if not stripped:
        return []
    parts = sqlparse.split(stripped)
    return [p.strip() for p in parts if p and p.strip()]


def _run_file_with_psql(filepath: str) -> Tuple[bool, str]:
    """
    Ganze Datei wie von psql dokumentiert (-1 eine Transaktion, ON_ERROR_STOP).
    Unter Windows oft nicht verfügbar → zurück False ohne Fehlertext wenn kein Binary.
    """
    psql = shutil.which("psql")
    if not psql:
        return False, ""

    p = _db_params()
    env = os.environ.copy()
    env["PGPASSWORD"] = str(p["password"])

    cmd = [
        psql,
        "-h",
        p["host"],
        "-p",
        str(p["port"]),
        "-U",
        p["user"],
        "-d",
        p["dbname"],
        "-v",
        "ON_ERROR_STOP=1",
        "-1",
        "-f",
        filepath,
    ]

    proc = subprocess.run(
        cmd,
        env=env,
        capture_output=True,
        text=True,
        timeout=7200,
    )
    if proc.returncode != 0:
        tail = (
            (proc.stderr or "").strip()
            + "\n"
            + (proc.stdout or "").strip()
        ).strip()
        return False, tail[:8000] or f"exit {proc.returncode}"
    out = (proc.stdout or "").strip()
    return True, out


def _record_migration(conn, migration_name: str) -> None:
    with conn.cursor() as cur:
        cur.execute(
            """
            INSERT INTO schema_migrations (migration)
            VALUES (%s)
            ON CONFLICT (migration) DO NOTHING
            """,
            (migration_name,),
        )


def run_migration(conn, migration_name: str, filepath: str) -> bool:
    print(f"Running migration: {migration_name}")

    detail_suffix = ""
    try:
        if shutil.which("psql"):
            ok, diag = _run_file_with_psql(filepath)
            if not ok:
                print(f"  [FAIL] psql fehlgeschlagen:\n{diag or '(kein Output)'}")
                conn.rollback()
                return False
            detail_suffix = "(psql -1)"
        else:
            try:
                with open(filepath, "r", encoding="utf-8") as fh:
                    body = fh.read()
            except OSError as e:
                print(f"  [FAIL] kann Datei nicht lesen: {e}")
                conn.rollback()
                return False

            statements = _split_statements(body)
            with conn.cursor() as cur:
                if not statements:
                    print(
                        f"  [WARN] keine ausführbaren Statements (leer?) — "
                        f"Eintrag trotzdem: {migration_name}"
                    )
                else:
                    for stmt in statements:
                        cur.execute(stmt)
            detail_suffix = f"(psycopg2 + sqlparse, {len(statements)} Statements)"

        _record_migration(conn, migration_name)
        conn.commit()
        print(f"  [OK] {migration_name} erfolgreich {detail_suffix}")
        return True

    except Exception as e:
        conn.rollback()
        print(f"  [FAIL] {migration_name}: {e}")
        return False


def main():
    print("=" * 60)
    print("Shinkan Jinkendo — Database Migrations")
    print("(Warteschlange: nur fehlende *.sql — idempotent)")
    print("=" * 60)

    migrations_dir = "/app/migrations"
    if not os.path.isdir(migrations_dir):
        migrations_dir = os.path.join(os.path.dirname(os.path.abspath(__file__)), "migrations")

    try:
        conn = get_db_connection()
        init_migrations_table(conn)

        pending = get_pending(conn, migrations_dir)

        if not pending:
            print("[OK] Keine ausstehenden Migrationen — Schema aktuell.")
            conn.close()
            return 0

        print(f"\n{len(pending)} ausstehende Migration(en):")
        for n, _ in pending:
            print(f"  - {n}")
        print()

        failed = None
        for migration_name, filepath in pending:
            if not run_migration(conn, migration_name, filepath):
                failed = migration_name
                break

        conn.close()

        print("\n" + "=" * 60)
        if failed:
            print(f"[FAIL] Abbruch nach: {failed}")
            print("  (Bereits erfolgreiche Dateien dieser Session sind committed.)")
            print("=" * 60)
            return 1

        print(f"[OK] {len(pending)} Migration(s) angewendet — Schema aktuell.")
        print("=" * 60)
        return 0

    except Exception as e:
        print(f"\n[FAIL] Fehler: {e}")
        return 1


if __name__ == "__main__":
    sys.exit(main())