#!/usr/bin/env python3
"""
Google Calendar Delegation Helper

Fetches calendar events via Google Calendar API, delegates analysis to appropriate model tier.

Usage:
    gcal_delegate.py today
    gcal_delegate.py tomorrow
    gcal_delegate.py week
    gcal_delegate.py next
    gcal_delegate.py summary
"""

import sys
import os
import json
import argparse
import subprocess
from datetime import datetime, timedelta, timezone
from pathlib import Path
from zoneinfo import ZoneInfo

# Local timezone for display
LOCAL_TZ = ZoneInfo('America/Los_Angeles')

# OAuth setup - reuse Gmail credentials location
CREDENTIALS_PATH = Path.home() / ".gmail-mcp" / "credentials.json"
TOKEN_PATH = Path.home() / ".gmail-mcp" / "calendar_token.json"
SCOPES = ['https://www.googleapis.com/auth/calendar.readonly']

# Claude CLI path
CLAUDE_CLI = "/home/linuxbrew/.linuxbrew/bin/claude"


def get_calendar_service():
    """Authenticate and return Calendar API service."""
    try:
        from google.oauth2.credentials import Credentials
        from google.auth.transport.requests import Request
        from google_auth_oauthlib.flow import InstalledAppFlow
        from googleapiclient.discovery import build
    except ImportError:
        print(json.dumps({
            "error": "Missing Google API libraries. Install with: pip install google-auth-oauthlib google-api-python-client"
        }))
        sys.exit(1)

    creds = None

    # Load existing token
    if TOKEN_PATH.exists():
        creds = Credentials.from_authorized_user_file(str(TOKEN_PATH), SCOPES)

    # Refresh or create new credentials
    if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
            try:
                creds.refresh(Request())
            except Exception:
                creds = None

        if not creds:
            if not CREDENTIALS_PATH.exists():
                print(json.dumps({
                    "error": f"OAuth credentials not found at {CREDENTIALS_PATH}. Set up Google Cloud OAuth first."
                }))
                sys.exit(1)

            flow = InstalledAppFlow.from_client_secrets_file(str(CREDENTIALS_PATH), SCOPES)
            creds = flow.run_local_server(port=0)

        # Save token for future use
        with open(TOKEN_PATH, 'w') as token:
            token.write(creds.to_json())

    return build('calendar', 'v3', credentials=creds)


def fetch_events(start: datetime, end: datetime, max_results: int = 50) -> list[dict]:
    """Fetch calendar events in time range."""
    service = get_calendar_service()

    events_result = service.events().list(
        calendarId='primary',
        timeMin=start.isoformat(),
        timeMax=end.isoformat(),
        maxResults=max_results,
        singleEvents=True,
        orderBy='startTime'
    ).execute()

    events = []
    for event in events_result.get('items', []):
        # Parse start time
        start_raw = event['start'].get('dateTime', event['start'].get('date'))
        if 'T' in start_raw:
            start_dt = datetime.fromisoformat(start_raw.replace('Z', '+00:00'))
            start_local = start_dt.astimezone(LOCAL_TZ)
            all_day = False
        else:
            start_dt = datetime.strptime(start_raw, '%Y-%m-%d')
            start_local = start_dt  # All-day events don't need TZ conversion
            all_day = True

        # Parse end time
        end_raw = event['end'].get('dateTime', event['end'].get('date'))
        if 'T' in end_raw:
            end_dt = datetime.fromisoformat(end_raw.replace('Z', '+00:00'))
        else:
            end_dt = datetime.strptime(end_raw, '%Y-%m-%d')

        # Calculate duration
        duration_mins = int((end_dt - start_dt).total_seconds() / 60) if not all_day else None

        # Extract location (could be URL or physical)
        location = event.get('location', '')
        hangout_link = event.get('hangoutLink', '')
        meeting_link = hangout_link or (location if location.startswith('http') else '')
        physical_location = location if location and not location.startswith('http') else ''

        # Attendee count
        attendees = event.get('attendees', [])
        attendee_count = len(attendees)

        events.append({
            'id': event['id'],
            'title': event.get('summary', '(no title)'),
            'start': start_raw,
            'start_formatted': start_local.strftime('%I:%M %p').lstrip('0') if not all_day else 'All day',
            'end': end_raw,
            'duration_mins': duration_mins,
            'all_day': all_day,
            'location': physical_location,
            'meeting_link': meeting_link,
            'attendee_count': attendee_count,
            'description': (event.get('description', '') or '')[:100],
            'date': start_local.strftime('%Y-%m-%d'),
            'day_name': start_local.strftime('%A'),
        })

    return events


def format_duration(mins: int) -> str:
    """Format duration in human-readable form."""
    if mins is None:
        return ""
    if mins < 60:
        return f"({mins}m)"
    hours = mins // 60
    remaining = mins % 60
    if remaining == 0:
        return f"({hours}h)"
    return f"({hours}h {remaining}m)"


def delegate(model: str, system: str, prompt: str, max_tokens: int = 4096) -> dict:
    """Delegate a task to Claude CLI using subscription."""
    try:
        cmd = [
            CLAUDE_CLI,
            "--print",
            "--model", model,
            "--system-prompt", system,
            "--output-format", "json",
            prompt
        ]

        result = subprocess.run(
            cmd,
            capture_output=True,
            text=True,
            timeout=120
        )

        if result.returncode != 0:
            return {"error": f"Claude CLI error: {result.stderr}"}

        try:
            output = json.loads(result.stdout)
            return {
                "success": True,
                "model": model,
                "content": output.get("result", ""),
                "usage": output.get("usage", {})
            }
        except json.JSONDecodeError:
            return {
                "success": True,
                "model": model,
                "content": result.stdout.strip(),
                "usage": {}
            }

    except subprocess.TimeoutExpired:
        return {"error": "Claude CLI timed out"}
    except FileNotFoundError:
        return {"error": f"Claude CLI not found at {CLAUDE_CLI}"}
    except Exception as e:
        return {"error": f"Unexpected error: {e}"}


def cmd_today() -> dict:
    """Get today's events."""
    # Use local time to determine "today"
    now_local = datetime.now(LOCAL_TZ)
    start_local = now_local.replace(hour=0, minute=0, second=0, microsecond=0)
    end_local = start_local + timedelta(days=1)

    # Convert to UTC for API query
    start_utc = start_local.astimezone(timezone.utc)
    end_utc = end_local.astimezone(timezone.utc)

    events = fetch_events(start_utc, end_utc)

    return {
        "tier": "haiku",
        "operation": "today",
        "date": start_local.strftime('%Y-%m-%d'),
        "day_name": start_local.strftime('%A'),
        "display_date": start_local.strftime('%A, %b %d'),
        "events": events,
        "count": len(events)
    }


def cmd_tomorrow() -> dict:
    """Get tomorrow's events."""
    # Use local time to determine "tomorrow"
    now_local = datetime.now(LOCAL_TZ)
    start_local = (now_local + timedelta(days=1)).replace(hour=0, minute=0, second=0, microsecond=0)
    end_local = start_local + timedelta(days=1)

    # Convert to UTC for API query
    start_utc = start_local.astimezone(timezone.utc)
    end_utc = end_local.astimezone(timezone.utc)

    events = fetch_events(start_utc, end_utc)

    return {
        "tier": "haiku",
        "operation": "tomorrow",
        "date": start_local.strftime('%Y-%m-%d'),
        "day_name": start_local.strftime('%A'),
        "display_date": start_local.strftime('%A, %b %d'),
        "events": events,
        "count": len(events)
    }


def cmd_week() -> dict:
    """Get next 7 days of events, grouped by day."""
    # Use local time to determine the week
    now_local = datetime.now(LOCAL_TZ)
    start_local = now_local.replace(hour=0, minute=0, second=0, microsecond=0)
    end_local = start_local + timedelta(days=7)

    # Convert to UTC for API query
    start_utc = start_local.astimezone(timezone.utc)
    end_utc = end_local.astimezone(timezone.utc)

    events = fetch_events(start_utc, end_utc, max_results=100)

    # Group by date (using local dates)
    by_day = {}
    for i in range(7):
        day = start_local + timedelta(days=i)
        day_str = day.strftime('%Y-%m-%d')
        by_day[day_str] = {
            "date": day_str,
            "day_name": day.strftime('%A'),
            "display_date": day.strftime('%A, %b %d'),
            "events": []
        }

    for event in events:
        day_str = event['date']
        if day_str in by_day:
            by_day[day_str]['events'].append(event)

    return {
        "tier": "haiku",
        "operation": "week",
        "start_date": start_local.strftime('%Y-%m-%d'),
        "end_date": end_local.strftime('%Y-%m-%d'),
        "display_range": f"{start_local.strftime('%b %d')} - {end_local.strftime('%b %d')}",
        "days": list(by_day.values()),
        "total_events": len(events)
    }


def cmd_next() -> dict:
    """Get next upcoming event."""
    now = datetime.now(timezone.utc)
    end = now + timedelta(days=7)  # Look ahead 7 days max

    events = fetch_events(now, end, max_results=5)

    # Filter to events that haven't started yet
    upcoming = [e for e in events if e['start'] > now.isoformat()]

    if not upcoming:
        return {
            "tier": "haiku",
            "operation": "next",
            "event": None,
            "message": "No upcoming events in the next 7 days."
        }

    return {
        "tier": "haiku",
        "operation": "next",
        "event": upcoming[0]
    }


def cmd_summary() -> dict:
    """Get smart summary of the week using Sonnet."""
    # First fetch the week's events
    week_data = cmd_week()

    if week_data['total_events'] == 0:
        return {
            "tier": "haiku",
            "operation": "summary",
            "summary": "Your week is clear — no events scheduled."
        }

    # Build context for Sonnet
    context = f"Calendar events for {week_data['display_range']}:\n\n"
    for day in week_data['days']:
        context += f"--- {day['display_date']} ---\n"
        if not day['events']:
            context += "(no events)\n"
        else:
            for event in day['events']:
                context += f"  {event['start_formatted']}: {event['title']}"
                if event['duration_mins']:
                    context += f" {format_duration(event['duration_mins'])}"
                if event['attendee_count'] > 1:
                    context += f" [{event['attendee_count']} attendees]"
                context += "\n"
        context += "\n"

    system = """You are a calendar analysis assistant. Provide concise, actionable summaries.
Focus on: busy vs free periods, meeting load, potential conflicts, and strategic insights.
Be brief — 2-4 sentences max. Highlight what's important."""

    prompt = f"""Analyze this calendar and provide a brief summary:

{context}

Key points: overall busyness, best times for deep work, anything notable."""

    result = delegate("sonnet", system, prompt, max_tokens=512)

    return {
        "tier": "sonnet",
        "operation": "summary",
        "total_events": week_data['total_events'],
        "summary": result.get("content", result.get("error", "Failed to analyze")),
        "usage": result.get("usage", {})
    }


def smart_default() -> str:
    """Return default command based on time of day."""
    hour = datetime.now().hour
    return "today" if hour < 18 else "tomorrow"


def main():
    parser = argparse.ArgumentParser(description="Google Calendar operations with tiered delegation")
    subparsers = parser.add_subparsers(dest="command")

    # Subcommands
    subparsers.add_parser("today", help="Today's agenda (Haiku tier)")
    subparsers.add_parser("tomorrow", help="Tomorrow's agenda (Haiku tier)")
    subparsers.add_parser("week", help="Next 7 days (Haiku tier)")
    subparsers.add_parser("next", help="Next upcoming event (Haiku tier)")
    subparsers.add_parser("summary", help="Smart week summary (Sonnet tier)")

    args = parser.parse_args()

    # Smart default if no command
    command = args.command or smart_default()

    try:
        if command == "today":
            result = cmd_today()
        elif command == "tomorrow":
            result = cmd_tomorrow()
        elif command == "week":
            result = cmd_week()
        elif command == "next":
            result = cmd_next()
        elif command == "summary":
            result = cmd_summary()
        else:
            result = {"error": f"Unknown command: {command}"}

        print(json.dumps(result, indent=2, default=str))

    except Exception as e:
        print(json.dumps({"error": str(e)}))
        sys.exit(1)


if __name__ == "__main__":
    main()