#!/usr/bin/env python3
"""
Quick JSON Schema Validator
Usage: python3 json_schema_validator.py <schema_file.json> <data_file.json>
Or: python3 json_schema_validator.py <schema_file.json> (reads JSON from stdin)

Exits with code 0 if valid, 1 if invalid, prints errors to stderr.
"""

import json
import sys
from typing import Any

try:
    from jsonschema import validate, ValidationError, Draft202012Validator
    HAS_JSONSCHEMA = True
except ImportError:
    HAS_JSONSCHEMA = False
    print("Installing jsonschema...", file=sys.stderr)
    import subprocess
    subprocess.check_call([sys.executable, "-m", "pip", "install", "jsonschema", "-q"])
    from jsonschema import validate, ValidationError, Draft202012Validator
    HAS_JSONSCHEMA = True


def load_json(path: str = None) -> Any:
    """Load JSON from file or stdin."""
    if path and path != "-":
        with open(path, 'r') as f:
            return json.load(f)
    return json.load(sys.stdin)


def validate_json(data: Any, schema: Any, schema_path: str = "<stdin>") -> list[str]:
    """Validate data against schema. Returns list of errors (empty if valid)."""
    if not HAS_JSONSCHEMA:
        return ["jsonschema package not available"]
    
    errors = []
    
    # Collect all validation errors (not just first)
    validator = Draft202012Validator(schema)
    for error in validator.iter_errors(data):
        path = " => ".join(str(p) for p in error.absolute_path) or "<root>"
        errors.append(f"{path}: {error.message}")
    
    return errors


def main():
    if len(sys.argv) < 2:
        print(__doc__, file=sys.stderr)
        sys.exit(1)
    
    schema_path = sys.argv[1]
    data_path = sys.argv[2] if len(sys.argv) > 2 else None
    
    try:
        schema = load_json(schema_path if schema_path != "-" else None)
    except FileNotFoundError:
        print(f"Error: Schema file not found: {schema_path}", file=sys.stderr)
        sys.exit(1)
    except json.JSONDecodeError as e:
        print(f"Error: Invalid JSON in schema: {e}", file=sys.stderr)
        sys.exit(1)
    
    try:
        data = load_json(data_path)
    except FileNotFoundError:
        print(f"Error: Data file not found: {data_path}", file=sys.stderr)
        sys.exit(1)
    except json.JSONDecodeError as e:
        print(f"Error: Invalid JSON in data: {e}", file=sys.stderr)
        sys.exit(1)
    
    errors = validate_json(data, schema, schema_path)
    
    if errors:
        print("Validation FAILED:", file=sys.stderr)
        for err in errors:
            print(f"  - {err}", file=sys.stderr)
        sys.exit(1)
    else:
        print("Validation PASSED")
        sys.exit(0)


if __name__ == "__main__":
    main()