from __future__ import annotations

import re
from pathlib import Path


CHAPTER_CATALOG = {
    1: "Relations and Functions",
    2: "Inverse Trigonometric Functions",
    3: "Matrices",
    4: "Determinants",
    5: "Continuity and Differentiability",
    6: "Application of Derivatives",
    7: "Integrals",
    8: "Application of Integrals",
    9: "Differential Equations",
    10: "Vector Algebra",
    11: "Three Dimensional Geometry",
    12: "Linear Programming",
    13: "Probability",
}


def parse_chapter_number(file_path: Path) -> int | None:
    match = re.search(r"chapter\s*([0-9]+)", file_path.stem, re.IGNORECASE)
    if not match:
        return None
    return int(match.group(1))


def clean_title(text: str) -> str:
    text = re.sub(r"\s+", " ", text.replace("_", " ")).strip()
    return text.title()


def pdf_metadata(file_path: Path) -> dict[str, str | int]:
    chapter_number = parse_chapter_number(file_path)
    chapter_name = CHAPTER_CATALOG.get(chapter_number or 0, clean_title(file_path.stem))
    return {
        "chapter_number": chapter_number or -1,
        "chapter_name": chapter_name,
        "source_file": file_path.name,
    }