"""
Cron job storage and execution.

Handles reading/writing CRONS.json and running jobs when they fire.
Imported by scheduler.py (to load jobs at startup) and tools/cron.py
(to add/remove jobs at runtime).

Job schema:
  {
    "id":         "c_abc123",
    "label":      "Human-readable name",
    "schedule":   "daily:09:00",   # see parse_schedule() for all formats
    "type":       "remind" | "note",
    "payload":    "Text to write when the job fires",
    "enabled":    true,
    "created_at": "ISO 8601",
    "last_run":   null | "ISO 8601"
  }

Job types:
  remind  → appends to inara/REMINDERS.md  (auto-loaded into Inara's context)
  note    → appends to inara/SCRATCH.md    (read on demand via scratch_read)
"""

import logging
from datetime import datetime, timezone
from pathlib import Path

from config import settings

logger = logging.getLogger(__name__)

_DEFAULT_HOUR = 9
_DEFAULT_MINUTE = 0

_DOW = {
    "mon": "mon", "tue": "tue", "wed": "wed", "thu": "thu",
    "fri": "fri", "sat": "sat", "sun": "sun",
    "monday": "mon", "tuesday": "tue", "wednesday": "wed",
    "thursday": "thu", "friday": "fri", "saturday": "sat", "sunday": "sun",
}


# ---------------------------------------------------------------------------
# Storage
# ---------------------------------------------------------------------------

def crons_path() -> Path:
    return settings.inara_path() / "CRONS.json"


def load_crons() -> list[dict]:
    p = crons_path()
    if not p.exists():
        return []
    try:
        import json
        return json.loads(p.read_text())
    except Exception:
        return []


def save_crons(crons: list[dict]) -> None:
    import json
    crons_path().write_text(json.dumps(crons, indent=2) + "\n")


# ---------------------------------------------------------------------------
# Schedule parsing
# ---------------------------------------------------------------------------

def parse_schedule(schedule: str) -> dict:
    """
    Convert a human schedule string to APScheduler cron kwargs.

    Formats:
      "hourly"           → every hour at :00
      "daily"            → every day at 09:00
      "daily:HH:MM"      → every day at HH:MM
      "weekly:DOW"       → every DOW at 09:00
      "weekly:DOW:HH:MM" → every DOW at HH:MM
    """
    s = schedule.strip().lower()

    if s == "hourly":
        return {"minute": 0}

    if s == "daily":
        return {"hour": _DEFAULT_HOUR, "minute": _DEFAULT_MINUTE}

    if s.startswith("daily:"):
        h, m = _parse_hhmm(s[6:], schedule)
        return {"hour": h, "minute": m}

    if s.startswith("weekly:"):
        rest = s[7:].split(":")
        dow = _DOW.get(rest[0])
        if not dow:
            raise ValueError(
                f"Unknown day of week {rest[0]!r}. "
                f"Use: mon tue wed thu fri sat sun"
            )
        if len(rest) == 3:
            h, m = _parse_hhmm(f"{rest[1]}:{rest[2]}", schedule)
        else:
            h, m = _DEFAULT_HOUR, _DEFAULT_MINUTE
        return {"day_of_week": dow, "hour": h, "minute": m}

    raise ValueError(
        f"Unrecognised schedule {schedule!r}. "
        f"Valid formats: hourly | daily | daily:HH:MM | weekly:DOW | weekly:DOW:HH:MM"
    )


def _parse_hhmm(s: str, original: str) -> tuple[int, int]:
    parts = s.split(":")
    if len(parts) != 2:
        raise ValueError(f"Expected HH:MM in {original!r}, got {s!r}")
    return int(parts[0]), int(parts[1])


# ---------------------------------------------------------------------------
# Execution
# ---------------------------------------------------------------------------

def _now_label() -> str:
    return datetime.now(timezone.utc).strftime("%Y-%m-%d %H:%M UTC")


async def run_job(job: dict) -> None:
    """Execute a cron job. Called by APScheduler when the job fires."""
    job_type = job.get("type")
    payload = job.get("payload", "").strip()
    label = job.get("label", job.get("id", "cron"))
    section = f"\n## {label} — {_now_label()}\n\n{payload}\n"

    inara_dir = settings.inara_path()

    if job_type == "remind":
        p = inara_dir / "REMINDERS.md"
        existing = p.read_text() if p.exists() else ""
        p.write_text(existing.rstrip() + "\n" + section)
        logger.info("cron [remind] fired: %s", label)

    elif job_type == "note":
        p = inara_dir / "SCRATCH.md"
        existing = p.read_text() if p.exists() else ""
        p.write_text(existing.rstrip() + "\n" + section)
        logger.info("cron [note] fired: %s", label)

    else:
        logger.warning("cron: unknown type %r (job %s)", job_type, job.get("id"))
        return

    # Record last_run
    crons = load_crons()
    for c in crons:
        if c["id"] == job["id"]:
            c["last_run"] = datetime.now(timezone.utc).isoformat()
            break
    save_crons(crons)