#!/usr/bin/env python3
"""JSONL validator - validates each line is valid JSON, reports errors with line numbers."""
import json
import sys
from pathlib import Path

def validate_jsonl(filepath: str) -> tuple[int, int]:
    """Validate JSONL file, return (valid_count, error_count)."""
    valid, errors = 0, 0
    with open(filepath, 'r') as f:
        for i, line in enumerate(f, 1):
            line = line.rstrip('\n\r')
            if not line:
                continue  # skip empty lines
            try:
                json.loads(line)
                valid += 1
            except json.JSONDecodeError as e:
                errors += 1
                print(f"Line {i}: {e.msg} at column {e.colno}")
    return valid, errors

if __name__ == '__main__':
    if len(sys.argv) < 2:
        print("Usage: jsonl_validator.py <file.jsonl>")
        sys.exit(1)
    
    path = Path(sys.argv[1])
    if not path.exists():
        print(f"Error: file not found: {path}")
        sys.exit(1)
    
    valid, errors = validate_jsonl(str(path))
    total = valid + errors
    print(f"\nValidated: {total} lines, {valid} valid, {errors} errors")
    sys.exit(0 if errors == 0 else 1)