#!/usr/bin/env python3
import json
import sys
import argparse
import os
from typing import Dict, Any, Optional

# Constants
VIEW_JSON_FILENAME = 'view.json'

def load_json_file(file_path: str) -> Optional[Dict[str, Any]]:
    """Loads JSON data from a file path. Returns the loaded dict or None on error."""
    if not os.path.exists(file_path):
        # This might be expected if a corresponding file doesn't exist in the baseline
        # print(f"Warning: File not found: '{file_path}'", file=sys.stderr)
        return None
    try:
        with open(file_path, 'r') as f:
            data = json.load(f)
        if not isinstance(data, dict):
            print(f"Error: Expected JSON root to be an object/dictionary in '{file_path}'", file=sys.stderr)
            return None # Treat as error
        return data
    except json.JSONDecodeError:
        print(f"Error: Invalid JSON format in file: '{file_path}'", file=sys.stderr)
        return None # Treat as error
    except IOError as e:
        print(f"Error reading file '{file_path}': {e}", file=sys.stderr)
        return None # Treat as error
    except Exception as e:
        print(f"An unexpected error occurred while loading '{file_path}': {e}", file=sys.stderr)
        return None # Treat as error

def compare_directories(dir1: str, dir2: str):
    """Compares view.json files found in subdirectories of dir1 with corresponding files in dir2."""
    print(f"Comparing '{VIEW_JSON_FILENAME}' files:")
    print(f"  Directory 1 (Modified): {dir1}")
    print(f"  Directory 2 (Baseline): {dir2}\n")

    differences_found = 0
    files_compared = 0
    errors_loading = 0
    baseline_missing = 0

    for root, _, files in os.walk(dir1):
        if VIEW_JSON_FILENAME in files:
            relative_path = os.path.relpath(root, dir1)
            file1_path = os.path.join(root, VIEW_JSON_FILENAME)
            file2_path = os.path.join(dir2, relative_path, VIEW_JSON_FILENAME)

            print(f"Comparing: {os.path.join(relative_path, VIEW_JSON_FILENAME)}")
            files_compared += 1

            data1 = load_json_file(file1_path)
            data2 = load_json_file(file2_path)

            if data1 is None:
                print(f"  - Error loading modified file: {file1_path}")
                errors_loading += 1
                continue # Cannot compare if modified file fails

            if data2 is None:
                # Check if the baseline file *should* exist
                if os.path.exists(os.path.dirname(file2_path)):
                     print(f"  - Baseline file missing or errored: {file2_path}")
                     baseline_missing += 1
                     # Decide if this counts as a difference? Yes, likely.
                     differences_found += 1
                else:
                     print(f"  - Baseline directory structure missing for: {os.path.join(relative_path, VIEW_JSON_FILENAME)}. Cannot compare.")
                     baseline_missing += 1 # Count as missing baseline structure
                continue # Cannot compare if baseline is missing/errored

            # Perform the comparison
            if data1 == data2:
                print("  - Identical")
            else:
                print("  - DIFFERENCE FOUND")
                differences_found += 1

    print("\n--- Comparison Summary ---")
    print(f"  View files compared: {files_compared}")
    print(f"  Files with differences: {differences_found}")
    print(f"  Errors loading modified files: {errors_loading}")
    print(f"  Baseline files missing/errored: {baseline_missing}")

    if differences_found == 0 and errors_loading == 0 and baseline_missing == 0:
        print("\nSuccess: All corresponding view.json files are logically identical.")
        return 0 # Exit code 0 for success
    else:
        print("\nCheck Complete: Differences or errors were encountered.")
        return 1 # Exit code 1 for differences/errors

def main():
    parser = argparse.ArgumentParser(
        description=f"Compares {VIEW_JSON_FILENAME} files between two directory structures.",
        formatter_class=argparse.ArgumentDefaultsHelpFormatter
    )
    parser.add_argument("dir1", help="Path to the first directory (e.g., the modified one).")
    parser.add_argument("dir2", help="Path to the second directory (e.g., the baseline/original one).")

    args = parser.parse_args()

    # Validate directories exist
    if not os.path.isdir(args.dir1):
        print(f"Error: Directory 1 not found: '{args.dir1}'", file=sys.stderr)
        sys.exit(1)
    if not os.path.isdir(args.dir2):
        print(f"Error: Directory 2 not found: '{args.dir2}'", file=sys.stderr)
        sys.exit(1)

    exit_code = compare_directories(args.dir1, args.dir2)
    sys.exit(exit_code)


if __name__ == "__main__":
    main()