"""
Aetheel Heartbeat System
========================
Parses HEARTBEAT.md and registers periodic tasks with the Scheduler.

Each section in HEARTBEAT.md defines a schedule (natural language header)
and one or more task prompts (bullet points). The HeartbeatRunner converts
these into cron jobs that fire synthetic messages through the AI handler.
"""

import logging
import os
import re
from dataclasses import dataclass

from config import HeartbeatConfig

logger = logging.getLogger("aetheel.heartbeat")


@dataclass
class HeartbeatTask:
    cron_expr: str
    prompt: str
    section_name: str


DEFAULT_HEARTBEAT_MD = """\
# Heartbeat Tasks

## Every 30 minutes
- Check if any scheduled reminders need attention

## Every morning (9:00 AM)
- Summarize yesterday's conversations

## Every evening (6:00 PM)
- Update MEMORY.md with today's key learnings
"""


class HeartbeatRunner:
    """Parses HEARTBEAT.md and registers tasks with the Scheduler."""

    def __init__(
        self,
        scheduler,
        ai_handler_fn,
        send_fn,
        config: HeartbeatConfig,
        workspace_dir: str,
    ):
        self._scheduler = scheduler
        self._ai_handler = ai_handler_fn
        self._send_fn = send_fn
        self._config = config
        self._workspace_dir = workspace_dir
        self._heartbeat_path = os.path.join(workspace_dir, "HEARTBEAT.md")

    def start(self) -> int:
        """Parse HEARTBEAT.md and register tasks. Returns count registered."""
        if not self._config.enabled:
            return 0

        self._ensure_heartbeat_file()
        tasks = self._parse_heartbeat_md()

        for task in tasks:
            self._scheduler.add_cron(
                cron_expr=task.cron_expr,
                prompt=task.prompt,
                channel_id=self._config.default_channel_id,
                channel_type="heartbeat",
            )

        logger.info(f"Heartbeat started: {len(tasks)} task(s) registered")
        return len(tasks)

    def _parse_heartbeat_md(self) -> list[HeartbeatTask]:
        """Parse HEARTBEAT.md sections into HeartbeatTask objects."""
        try:
            with open(self._heartbeat_path, "r", encoding="utf-8") as f:
                content = f.read()
        except FileNotFoundError:
            logger.warning(f"HEARTBEAT.md not found at {self._heartbeat_path}")
            return []
        except Exception as e:
            logger.warning(f"Failed to read HEARTBEAT.md: {e}")
            return []

        tasks: list[HeartbeatTask] = []
        current_header: str | None = None
        current_cron: str | None = None

        for line in content.splitlines():
            stripped = line.strip()

            # Match ## section headers (schedule definitions)
            if stripped.startswith("## "):
                header_text = stripped[3:].strip()
                cron = self._parse_schedule_header(header_text)
                if cron is not None:
                    current_header = header_text
                    current_cron = cron
                else:
                    logger.warning(
                        f"Unrecognized schedule header: '{header_text}' — skipping section"
                    )
                    current_header = None
                    current_cron = None
                continue

            # Match bullet points under a valid section
            if current_cron is not None and stripped.startswith("- "):
                prompt = stripped[2:].strip()
                if prompt:
                    tasks.append(
                        HeartbeatTask(
                            cron_expr=current_cron,
                            prompt=prompt,
                            section_name=current_header or "",
                        )
                    )

        return tasks

    def _ensure_heartbeat_file(self) -> None:
        """Create default HEARTBEAT.md if it doesn't exist."""
        if os.path.exists(self._heartbeat_path):
            return

        os.makedirs(os.path.dirname(self._heartbeat_path), exist_ok=True)

        with open(self._heartbeat_path, "w", encoding="utf-8") as f:
            f.write(DEFAULT_HEARTBEAT_MD)

        logger.info(f"Created default HEARTBEAT.md at {self._heartbeat_path}")

    @staticmethod
    def _parse_schedule_header(header: str) -> str | None:
        """Convert a natural language schedule header to a cron expression.

        Supported patterns:
            "Every 30 minutes"       -> */30 * * * *
            "Every N minutes"        -> */N * * * *
            "Every hour"             -> 0 * * * *
            "Every N hours"          -> 0 */N * * *
            "Every morning (9:00 AM)"  -> 0 9 * * *
            "Every evening (6:00 PM)"  -> 0 18 * * *

        Returns None for unrecognized patterns.
        """
        h = header.strip()

        # "Every hour"
        if re.match(r"^every\s+hour$", h, re.IGNORECASE):
            return "0 * * * *"

        # "Every N minutes"
        m = re.match(r"^every\s+(\d+)\s+minutes?$", h, re.IGNORECASE)
        if m:
            n = int(m.group(1))
            return f"*/{n} * * * *"

        # "Every N hours"
        m = re.match(r"^every\s+(\d+)\s+hours?$", h, re.IGNORECASE)
        if m:
            n = int(m.group(1))
            return f"0 */{n} * * *"

        # "Every morning (H:MM AM)" or "Every morning (H AM)"
        m = re.match(
            r"^every\s+morning\s*\(\s*(\d{1,2})(?::(\d{2}))?\s*(AM|PM)\s*\)$",
            h,
            re.IGNORECASE,
        )
        if m:
            hour = int(m.group(1))
            minute = int(m.group(2)) if m.group(2) else 0
            period = m.group(3).upper()
            hour = _to_24h(hour, period)
            return f"{minute} {hour} * * *"

        # "Every evening (H:MM PM)" or "Every evening (H PM)"
        m = re.match(
            r"^every\s+evening\s*\(\s*(\d{1,2})(?::(\d{2}))?\s*(AM|PM)\s*\)$",
            h,
            re.IGNORECASE,
        )
        if m:
            hour = int(m.group(1))
            minute = int(m.group(2)) if m.group(2) else 0
            period = m.group(3).upper()
            hour = _to_24h(hour, period)
            return f"{minute} {hour} * * *"

        return None


def _to_24h(hour: int, period: str) -> int:
    """Convert 12-hour time to 24-hour."""
    if period == "AM":
        return 0 if hour == 12 else hour
    else:  # PM
        return hour if hour == 12 else hour + 12