from __future__ import annotations

import json
import tomllib
from dataclasses import dataclass
from pathlib import Path
from urllib.parse import urlparse


@dataclass(frozen=True)
class RepositoryMetadata:
    name: str
    description: str | None


class RepositoryMetadataExtractor:
    def extract(self, source_path: str | Path, url: str) -> RepositoryMetadata:
        root = Path(source_path)
        pyproject = self._from_pyproject(root)
        package = self._from_package_json(root)
        readme = self._from_readme(root)
        fallback_name = self._name_from_url_or_path(url)

        return RepositoryMetadata(
            name=pyproject.name or package.name or readme.name or fallback_name,
            description=(
                pyproject.description
                or package.description
                or readme.description
            ),
        )

    def _from_pyproject(self, root: Path) -> RepositoryMetadata:
        path = root / "pyproject.toml"
        if not path.exists():
            return RepositoryMetadata(name="", description=None)
        try:
            project = tomllib.loads(path.read_text(encoding="utf-8")).get("project", {})
        except (OSError, tomllib.TOMLDecodeError):
            return RepositoryMetadata(name="", description=None)
        return RepositoryMetadata(
            name=str(project.get("name") or ""),
            description=project.get("description"),
        )

    def _from_package_json(self, root: Path) -> RepositoryMetadata:
        path = root / "package.json"
        if not path.exists():
            return RepositoryMetadata(name="", description=None)
        try:
            package = json.loads(path.read_text(encoding="utf-8"))
        except (OSError, json.JSONDecodeError):
            return RepositoryMetadata(name="", description=None)
        return RepositoryMetadata(
            name=str(package.get("name") or ""),
            description=package.get("description"),
        )

    def _from_readme(self, root: Path) -> RepositoryMetadata:
        for readme in sorted(root.glob("README*")):
            if not readme.is_file():
                continue
            try:
                lines = readme.read_text(encoding="utf-8", errors="ignore").splitlines()
            except OSError:
                continue
            title = ""
            for line in lines:
                stripped = line.strip()
                cleaned = stripped.strip("#").strip()
                if stripped.startswith("#") and cleaned and not title:
                    title = cleaned
                    continue
                if cleaned:
                    return RepositoryMetadata(name=title, description=cleaned)
            if title:
                return RepositoryMetadata(name=title, description=None)
        return RepositoryMetadata(name="", description=None)

    def _name_from_url_or_path(self, value: str) -> str:
        parsed = urlparse(value)
        path = parsed.path if parsed.scheme else value
        name = Path(path.rstrip("/")).name or "repository"
        if name.endswith(".git"):
            name = name[:-4]
        return name or "repository"