#!/usr/bin/env python3
"""
Queue Health Check — Verify dispatch queue is operational.

Checks:
1. Queue file exists and is readable
2. Queue has pending items
3. Queue is not stuck (items processing)
4. Queue age (stale items)

Usage:
    python scripts/queue_health_check.py
    python scripts/queue_health_check.py --json
"""

import json
import sys
from datetime import datetime, timedelta
from pathlib import Path


def check_queue_health(queue_path: str = "~/.hermes/queue.json") -> dict:
    """Check queue health status."""
    path = Path(queue_path).expanduser()
    
    result = {
        "healthy": True,
        "checks": {},
        "warnings": [],
        "errors": []
    }
    
    # Check 1: File exists
    if not path.exists():
        result["healthy"] = False
        result["errors"].append(f"Queue file not found: {path}")
        result["checks"]["file_exists"] = False
        return result
    
    result["checks"]["file_exists"] = True
    
    # Check 2: File is readable
    try:
        with open(path, "r") as f:
            data = json.load(f)
    except Exception as e:
        result["healthy"] = False
        result["errors"].append(f"Cannot read queue: {e}")
        result["checks"]["readable"] = False
        return result
    
    result["checks"]["readable"] = True
    
    # Check 3: Queue structure
    if not isinstance(data, dict):
        result["healthy"] = False
        result["errors"].append("Queue is not a dict")
        result["checks"]["valid_structure"] = False
        return result
    
    result["checks"]["valid_structure"] = True
    
    # Check 4: Pending items
    pending = data.get("pending", [])
    processing = data.get("processing", [])
    completed = data.get("completed", [])
    
    result["checks"]["pending_count"] = len(pending)
    result["checks"]["processing_count"] = len(processing)
    result["checks"]["completed_count"] = len(completed)
    
    if len(pending) == 0 and len(processing) == 0:
        result["warnings"].append("Queue is empty")
    
    # Check 5: Stale processing items
    now = datetime.now()
    stale_threshold = timedelta(hours=1)
    
    for item in processing:
        started = item.get("started_at")
        if started:
            try:
                started_time = datetime.fromisoformat(started.replace("Z", "+00:00"))
                if now - started_time > stale_threshold:
                    result["warnings"].append(f"Stale item: {item.get('id', 'unknown')} (started {started})")
            except:
                pass
    
    # Check 6: Queue age
    if pending:
        oldest = min(pending, key=lambda x: x.get("added_at", ""))
        added = oldest.get("added_at")
        if added:
            try:
                added_time = datetime.fromisoformat(added.replace("Z", "+00:00"))
                age = now - added_time
                if age > timedelta(hours=24):
                    result["warnings"].append(f"Old item in queue: {oldest.get('id', 'unknown')} (added {added})")
            except:
                pass
    
    return result


def main():
    """Main function."""
    import argparse
    
    parser = argparse.ArgumentParser(description="Queue health check")
    parser.add_argument("--queue", default="~/.hermes/queue.json", help="Queue file path")
    parser.add_argument("--json", action="store_true", help="Output as JSON")
    args = parser.parse_args()
    
    result = check_queue_health(args.queue)
    
    if args.json:
        print(json.dumps(result, indent=2))
    else:
        print("Queue Health Check")
        print("=" * 50)
        print(f"Healthy: {'✓' if result['healthy'] else '✗'}")
        print()
        
        print("Checks:")
        for check, value in result["checks"].items():
            if isinstance(value, bool):
                print(f"  {check}: {'✓' if value else '✗'}")
            else:
                print(f"  {check}: {value}")
        
        if result["warnings"]:
            print()
            print("Warnings:")
            for warning in result["warnings"]:
                print(f"  ⚠ {warning}")
        
        if result["errors"]:
            print()
            print("Errors:")
            for error in result["errors"]:
                print(f"  ✗ {error}")
    
    sys.exit(0 if result["healthy"] else 1)


if __name__ == "__main__":
    main()