from pathlib import Path

import yaml

from .errors import ParseError, ValidationError
from .models import SkillProperties


def find_skill_md(skill_dir: Path) -> Path | None:
    for name in ("SKILL.md", "skill.md"):
        path = skill_dir / name
        if path.exists():
            return path
    return None


def parse_frontmatter(content: str) -> tuple[dict, str]:
    if not content.startswith("---"):
        raise ParseError("SKILL.md must start with YAML frontmatter (---)")

    parts = content.split("---", 2)
    if len(parts) < 3:
        raise ParseError("SKILL.md frontmatter not properly closed with ---")

    frontmatter_str = parts[1]
    body = parts[2].strip()

    try:
        metadata = yaml.safe_load(frontmatter_str)
    except yaml.YAMLError as exc:
        raise ParseError(f"Invalid YAML in frontmatter: {exc}") from exc

    if not isinstance(metadata, dict):
        raise ParseError("SKILL.md frontmatter must be a YAML mapping")

    if "metadata" in metadata and isinstance(metadata["metadata"], dict):
        metadata["metadata"] = {
            str(key): str(value) for key, value in metadata["metadata"].items()
        }

    return metadata, body


def read_properties(skill_dir: Path) -> SkillProperties:
    skill_dir = Path(skill_dir)
    skill_md = find_skill_md(skill_dir)

    if skill_md is None:
        raise ParseError(f"SKILL.md not found in {skill_dir}")

    content = skill_md.read_text(encoding="utf-8")
    metadata, _ = parse_frontmatter(content)

    if "name" not in metadata:
        raise ValidationError("Missing required field in frontmatter: name")
    if "description" not in metadata:
        raise ValidationError("Missing required field in frontmatter: description")

    name = metadata["name"]
    description = metadata["description"]

    if not isinstance(name, str) or not name.strip():
        raise ValidationError("Field 'name' must be a non-empty string")
    if not isinstance(description, str) or not description.strip():
        raise ValidationError("Field 'description' must be a non-empty string")

    return SkillProperties(
        name=name.strip(),
        description=description.strip(),
        license=metadata.get("license"),
        compatibility=metadata.get("compatibility"),
        allowed_tools=metadata.get("allowed-tools"),
        metadata=metadata.get("metadata"),
    )