"""Health check payload for /api/health."""

from __future__ import annotations

from pathlib import Path
from typing import Any, Dict, Optional, Tuple

from flask import Flask


def _project_root(app: Flask) -> Path:
    root = Path(__file__).resolve().parent.parent.parent
    ini = root / "alembic.ini"
    if ini.is_file():
        return root
    return Path(app.config["BASE_DIR"])


def _alembic_head_revision(app: Flask) -> Optional[str]:
    try:
        from alembic.config import Config as AlembicConfig
        from alembic.script import ScriptDirectory

        root = _project_root(app)
        ini = root / "alembic.ini"
        if not ini.is_file():
            return None
        cfg = AlembicConfig(str(ini))
        cfg.set_main_option("script_location", str(root / "migrations"))
        return ScriptDirectory.from_config(cfg).get_current_head()
    except Exception:
        return None


def _db_migration_revision(app: Flask) -> Tuple[Optional[str], bool]:
    """(текущая ревизия в recipes.db, таблица alembic_version есть)."""
    try:
        from sqlalchemy import inspect, text

        from app import db

        insp = inspect(db.engine)
        if not insp.has_table("alembic_version"):
            return None, False
        rev = db.session.execute(text("SELECT version_num FROM alembic_version LIMIT 1")).scalar()
        return (str(rev) if rev is not None else None), True
    except Exception:
        try:
            from app import db

            db.session.rollback()
        except Exception:
            pass
        return None, False


def migrations_ok_for_app(app: Flask) -> bool:
    if app.config.get("TESTING"):
        return True
    head = _alembic_head_revision(app)
    current, has_table = _db_migration_revision(app)
    if head is None:
        return has_table
    if not has_table:
        return False
    return current == head


def build_health_payload(app: Flask) -> Dict[str, Any]:
    ver = str(app.config.get("SYNC_CLIENT_VERSION", "2.0.0") or "2.0.0")

    from app.services.startup_background import is_startup_ready_implicit
    from app.services.startup_state import startup_status_payload

    if not is_startup_ready_implicit(app):
        st = startup_status_payload()
        return {
            "ok": False,
            "starting": True,
            "version": ver,
            "db_ok": False,
            "migrations_ok": False,
            **st,
        }

    db_ok = True
    migrations_ok = True
    migration_revision: Optional[str] = None
    migration_head: Optional[str] = None

    if not app.config.get("TESTING"):
        try:
            from app import db
            from sqlalchemy import text

            db.session.execute(text("SELECT 1"))
            db.session.commit()
        except Exception:
            db_ok = False
            try:
                from app import db

                db.session.rollback()
            except Exception:
                pass

        migration_head = _alembic_head_revision(app)
        migration_revision, _ = _db_migration_revision(app)
        migrations_ok = migrations_ok_for_app(app)

    ok = db_ok and migrations_ok
    payload: Dict[str, Any] = {
        "ok": ok,
        "version": ver,
        "db_ok": db_ok,
        "migrations_ok": migrations_ok,
    }
    if migration_revision is not None:
        payload["migration_revision"] = migration_revision
    if migration_head is not None:
        payload["migration_head"] = migration_head
    return payload