#!/usr/bin/env python3
"""
View and analyze Claude Code logs.
Usage: python3 log-viewer.py [--tail N] [--grep PATTERN] [--since DATE] [--type TYPE]
"""

import argparse
import json
import os
import re
import sys
from datetime import datetime, timedelta
from pathlib import Path
from typing import List, Optional

CLAUDE_DIR = Path.home() / ".claude"
LOG_DIR = CLAUDE_DIR / "logs"


def get_log_files(log_type: Optional[str] = None) -> List[Path]:
    """Get list of log files, optionally filtered by type."""
    if not LOG_DIR.exists():
        return []

    files = list(LOG_DIR.glob("*.log"))

    if log_type:
        files = [f for f in files if log_type in f.name]

    return sorted(files, key=lambda f: f.stat().st_mtime, reverse=True)


def parse_log_line(line: str) -> Optional[dict]:
    """Parse a log line into structured data."""
    # Try JSON format
    try:
        return json.loads(line)
    except json.JSONDecodeError:
        pass

    # Try timestamp format: [YYYY-MM-DD HH:MM:SS] message
    match = re.match(r'\[(\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2})\] (.+)', line)
    if match:
        return {
            "timestamp": match.group(1),
            "message": match.group(2)
        }

    # Plain text
    return {"message": line.strip()} if line.strip() else None


def filter_by_date(entries: List[dict], since: str) -> List[dict]:
    """Filter entries by date."""
    try:
        since_date = datetime.strptime(since, "%Y-%m-%d")
    except ValueError:
        try:
            # Try relative (e.g., "1d", "7d", "1h")
            if since.endswith("d"):
                days = int(since[:-1])
                since_date = datetime.now() - timedelta(days=days)
            elif since.endswith("h"):
                hours = int(since[:-1])
                since_date = datetime.now() - timedelta(hours=hours)
            else:
                return entries
        except ValueError:
            return entries

    result = []
    for entry in entries:
        ts = entry.get("timestamp", "")
        if ts:
            try:
                entry_date = datetime.strptime(ts[:19], "%Y-%m-%d %H:%M:%S")
                if entry_date >= since_date:
                    result.append(entry)
            except ValueError:
                result.append(entry)  # Include if can't parse
        else:
            result.append(entry)

    return result


def grep_entries(entries: List[dict], pattern: str) -> List[dict]:
    """Filter entries by grep pattern."""
    regex = re.compile(pattern, re.IGNORECASE)
    result = []
    for entry in entries:
        message = entry.get("message", "")
        if regex.search(message):
            result.append(entry)
    return result


def tail_file(path: Path, n: int = 50) -> List[str]:
    """Get last N lines from a file."""
    try:
        with open(path) as f:
            lines = f.readlines()
            return lines[-n:]
    except Exception:
        return []


def format_entry(entry: dict) -> str:
    """Format a log entry for display."""
    ts = entry.get("timestamp", "")
    msg = entry.get("message", "")

    if ts:
        return f"[{ts}] {msg}"
    return msg


def list_logs():
    """List available log files."""
    files = get_log_files()

    if not files:
        print("No log files found.")
        return

    print(f"\n📋 Log Files ({len(files)})\n")
    print(f"{'File':<40} {'Size':<10} {'Modified'}")
    print("-" * 70)

    for f in files:
        stat = f.stat()
        size = stat.st_size
        if size > 1024 * 1024:
            size_str = f"{size / 1024 / 1024:.1f}M"
        elif size > 1024:
            size_str = f"{size / 1024:.1f}K"
        else:
            size_str = f"{size}B"

        mtime = datetime.fromtimestamp(stat.st_mtime).strftime("%Y-%m-%d %H:%M")
        print(f"{f.name:<40} {size_str:<10} {mtime}")

    print("")


def view_log(filename: str, tail: int = 50, grep: Optional[str] = None,
             since: Optional[str] = None):
    """View a specific log file."""
    # Find the log file
    log_path = LOG_DIR / filename
    if not log_path.exists():
        # Try with .log extension
        log_path = LOG_DIR / f"{filename}.log"

    if not log_path.exists():
        print(f"Log file not found: {filename}")
        return

    lines = tail_file(log_path, tail * 2 if grep else tail)  # Get more if filtering

    entries = []
    for line in lines:
        entry = parse_log_line(line)
        if entry:
            entries.append(entry)

    if since:
        entries = filter_by_date(entries, since)

    if grep:
        entries = grep_entries(entries, grep)

    # Limit to tail after filtering
    entries = entries[-tail:]

    print(f"\n📜 {log_path.name} (last {len(entries)} entries)\n")
    print("-" * 70)

    for entry in entries:
        print(format_entry(entry))

    print("")


def main():
    parser = argparse.ArgumentParser(description="View Claude Code logs")
    parser.add_argument("file", nargs="?", help="Log file to view")
    parser.add_argument("--list", "-l", action="store_true", help="List log files")
    parser.add_argument("--tail", "-n", type=int, default=50,
                       help="Number of lines to show (default: 50)")
    parser.add_argument("--grep", "-g", type=str, help="Filter by pattern")
    parser.add_argument("--since", "-s", type=str,
                       help="Show entries since date (YYYY-MM-DD or 1d/7d/1h)")
    parser.add_argument("--type", "-t", type=str,
                       help="Filter log files by type (maintenance, etc.)")

    args = parser.parse_args()

    if args.list:
        list_logs()
    elif args.file:
        view_log(args.file, tail=args.tail, grep=args.grep, since=args.since)
    else:
        # Default: show most recent log
        files = get_log_files(args.type)
        if files:
            view_log(files[0].name, tail=args.tail, grep=args.grep, since=args.since)
        else:
            print("No log files found. Run some automation scripts first.")


if __name__ == "__main__":
    main()