"""JSON-backed task definition CRUD with file locking."""

from __future__ import annotations

import json
import logging
from pathlib import Path

from filelock import FileLock

from config.constants import OPENSRE_HOME_DIR
from platform.scheduler.claim_store import _DB_FILENAME, delete_runs
from platform.scheduler.types import ScheduledTask

logger = logging.getLogger(__name__)

_STORE_FILENAME = "scheduler_tasks.json"


def _default_store_path() -> Path:
    return OPENSRE_HOME_DIR / _STORE_FILENAME


def _lock_path(store_path: Path) -> Path:
    return store_path.with_suffix(".lock")


def _load_raw(store_path: Path) -> list[dict[str, object]]:
    """Load raw task list from disk."""
    if not store_path.exists():
        return []
    try:
        data = json.loads(store_path.read_text(encoding="utf-8"))
    except (json.JSONDecodeError, OSError) as exc:
        logger.warning("Failed to read scheduler store: %s", exc)
        return []
    if not isinstance(data, list):
        return []
    return data  # type: ignore[return-value]


def _save_raw(store_path: Path, data: list[dict[str, object]]) -> None:
    """Persist task list to disk."""
    store_path.parent.mkdir(parents=True, exist_ok=True)
    store_path.write_text(json.dumps(data, indent=2, default=str) + "\n", encoding="utf-8")


def list_tasks(store_path: Path | None = None) -> list[ScheduledTask]:
    """Return all persisted scheduled tasks."""
    path = store_path or _default_store_path()
    lock = FileLock(_lock_path(path))
    with lock:
        raw = _load_raw(path)
    tasks: list[ScheduledTask] = []
    for entry in raw:
        try:
            tasks.append(ScheduledTask.model_validate(entry))
        except Exception as exc:  # noqa: BLE001
            logger.warning("Skipping invalid task entry: %s", exc)
    return tasks


def get_task(task_id: str, store_path: Path | None = None) -> ScheduledTask | None:
    """Return a single task by ID, or None if not found."""
    for task in list_tasks(store_path):
        if task.id == task_id:
            return task
    return None


def add_task(task: ScheduledTask, store_path: Path | None = None) -> ScheduledTask:
    """Persist a new scheduled task. Returns the task with its generated ID."""
    path = store_path or _default_store_path()
    lock = FileLock(_lock_path(path))
    with lock:
        raw = _load_raw(path)
        raw.append(task.model_dump(mode="json"))
        _save_raw(path, raw)
    return task


def remove_task(task_id: str, store_path: Path | None = None) -> bool:
    """Remove a task by ID and cascade-delete its run records.

    Returns True if the task was found and removed from the JSON store.
    Cascade deletion of ``TaskRun`` records in the SQLite claim store is
    best-effort — a warning is logged on failure but the return value
    reflects only the JSON-store result.
    """
    path = store_path or _default_store_path()
    lock = FileLock(_lock_path(path))
    with lock:
        raw = _load_raw(path)
        original_len = len(raw)
        raw = [entry for entry in raw if entry.get("id") != task_id]
        if len(raw) == original_len:
            return False
        _save_raw(path, raw)

    # Cascade: remove orphaned TaskRun records from the SQLite claim store.
    # Derive the DB path from the same directory as the JSON store.
    db_path = path.with_name(_DB_FILENAME)
    try:
        deleted = delete_runs(task_id, db_path)
        if deleted:
            logger.info("Cascade-deleted %d run(s) for removed task %s", deleted, task_id)
    except Exception:  # noqa: BLE001
        logger.warning(
            "Failed to cascade-delete runs for task %s (DB: %s); orphaned runs may remain",
            task_id,
            db_path,
            exc_info=True,
        )

    return True


def update_task(task: ScheduledTask, store_path: Path | None = None) -> bool:
    """Update an existing task in the store. Returns True if found and updated."""
    path = store_path or _default_store_path()
    lock = FileLock(_lock_path(path))
    with lock:
        raw = _load_raw(path)
        for i, entry in enumerate(raw):
            if entry.get("id") == task.id:
                raw[i] = task.model_dump(mode="json")
                _save_raw(path, raw)
                return True
    return False


__all__ = [
    "add_task",
    "get_task",
    "list_tasks",
    "remove_task",
    "update_task",
]