#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Chapter Paths Module

Provides utilities for finding and managing chapter files.
"""

from pathlib import Path
from typing import Optional


def default_chapter_draft_path(project_root: Path, chapter_num: int) -> Path:
    """
    Get the default path for a chapter draft.

    Args:
        project_root: Project root directory
        chapter_num: Chapter number

    Returns:
        Path to the chapter draft file
    """
    return project_root / "chapters" / f"chapter_{chapter_num:04d}.txt"


def find_chapter_file(project_root: Path, chapter_num: int) -> Optional[Path]:
    """
    Find a chapter file by number.

    Args:
        project_root: Project root directory
        chapter_num: Chapter number

    Returns:
        Path to the chapter file if found, None otherwise
    """
    # Try default path
    default_path = default_chapter_draft_path(project_root, chapter_num)
    if default_path.exists():
        return default_path

    # Try alternative naming patterns
    patterns = [
        f"chapter_{chapter_num:04d}.txt",
        f"chapter_{chapter_num}.txt",
        f"第{chapter_num}章.txt",
        f"ch{chapter_num:04d}.txt",
    ]

    chapters_dir = project_root / "chapters"
    if not chapters_dir.exists():
        return None

    for pattern in patterns:
        for file in chapters_dir.glob(pattern):
            return file

    return None


def list_chapters(project_root: Path) -> list[int]:
    """
    List all chapter numbers in the project.

    Args:
        project_root: Project root directory

    Returns:
        List of chapter numbers
    """
    chapters_dir = project_root / "chapters"
    if not chapters_dir.exists():
        return []

    chapters = []
    for file in chapters_dir.glob("chapter_*.txt"):
        try:
            num = int(file.stem.split("_")[1])
            chapters.append(num)
        except (ValueError, IndexError):
            continue

    return sorted(chapters)