#!/usr/bin/env python3
"""
Replace JRiver date imported fields with date modified when the latter is earlier.
"""

import sys
from pathlib import Path


def get_import_date(line: str) -> int:
    """Extract and return the date imported value from a date imported field."""
    date = line.lstrip('<Field Name="Date Imported">').rstrip('</Field>\n')
    return int(date)


def get_create_date(line: str) -> int:
    """Extract and return the date modified value from a date modified field."""
    date = line.lstrip('<Field Name="Date Modified">').rstrip('</Field>\n')
    return int(date)


def main() -> None:
    """Main function to process JRiver library file."""
    if len(sys.argv) != 3:
        print("Usage: jriver-replace-date-imported <input_file> <output_file>", file=sys.stderr)
        sys.exit(1)

    in_file = Path(sys.argv[1])
    out_file = Path(sys.argv[2])

    if not in_file.exists():
        print(f"[ERROR] Input file '{in_file}' does not exist.", file=sys.stderr)
        sys.exit(1)

    # Read input file
    with open(in_file, "r", encoding="utf-8") as f:
        lines = f.readlines()

    # Process lines and replace dates where appropriate
    import_date: int = 0
    date_imported_line: int = 0
    replacements = 0

    for lnum, line in enumerate(lines):
        if '<Field Name="Date Imported">' in line:
            import_date = get_import_date(line)
            date_imported_line = lnum
        elif '<Field Name="Date Modified">' in line:
            create_date = get_create_date(line)
            if create_date < import_date:
                print(f"[INFO] Replacing {import_date} with {create_date} at line {date_imported_line}")
                lines[date_imported_line] = f'<Field Name="Date Imported">{create_date}</Field>\n'
                replacements += 1

    # Write output file
    with open(out_file, 'w', encoding="utf-8") as f:
        f.writelines(lines)

    print(f"[SUCCESS] Made {replacements} replacements. Output written to '{out_file}'.")


if __name__ == "__main__":
    main()