#!/usr/bin/env python3
"""
compare_names.py

Compares the `deviceName` values from File 1 with the `name` values from File 2.
If a `deviceName` does not appear in File 2, it is written to *missing.txt*.
"""

import json
import argparse
import sys
from pathlib import Path

def load_json(path: Path):
    """Return the parsed JSON data from *path*."""
    try:
        with path.open("r", encoding="utf-8") as f:
            return json.load(f)
    except FileNotFoundError:
        print(f"❌  File not found: {path}", file=sys.stderr)
        sys.exit(1)
    except json.JSONDecodeError as exc:
        print(f"❌  Invalid JSON in {path}:\n{exc}", file=sys.stderr)
        sys.exit(1)

def extract_device_names_from_file1(data):
    """Return a list of deviceName values from the File 1 structure."""
    names = []
    for mac, obj in data.items():
        # Some devices may not have a name; skip them quietly.
        name = obj.get("deviceName")
        if isinstance(name, str):
            names.append(name)
    return names

def extract_names_from_file2(data):
    """Return a set of name values from the File 2 list."""
    names = set()
    for entry in data:
        name = entry.get("name")
        if isinstance(name, str):
            names.add(name)
    return names

def main(file1_path: Path, file2_path: Path, output_path: Path):
    # Load data
    data1 = load_json(file1_path)
    data2 = load_json(file2_path)

    # Pull out the two collections we care about
    names_in_file1 = extract_device_names_from_file1(data1)
    names_in_file2 = extract_names_from_file2(data2)

    # Find names that are missing from File 2
    missing = [name for name in names_in_file1 if name not in names_in_file2]

    # Output
    if missing:
        print(f"⚠️  Found {len(missing)} device(s) whose name is missing in File 2.")
        # Write to a text file – one name per line
        with output_path.open("w", encoding="utf-8") as out:
            out.write("\n".join(missing))
        print(f"✔️  Missing names written to {output_path}")
    else:
        print("✅  All deviceNames from File 1 are present in File 2.")

if __name__ == "__main__":
    parser = argparse.ArgumentParser(
        description="Find deviceName values in File 1 that are not present in File 2."
    )
    parser.add_argument("file1", type=Path, help="Path to File 1 (JSON dict).")
    parser.add_argument("file2", type=Path, help="Path to File 2 (JSON list).")
    parser.add_argument(
        "-o",
        "--output",
        type=Path,
        default=Path("missing.txt"),
        help="Where to write the list of missing names (default: missing.txt)",
    )
    args = parser.parse_args()
    main(args.file1, args.file2, args.output)