"""Markdown skill registry.

Skills are .md files in the skills/ directory with YAML frontmatter:

    ---
    name: press-release-writer
    description: Write professional press releases
    tools: [write_press_releases, submit_press_release]
    agents: [writer, default]
    ---
    # Press Release Workflow
    ...

Files without frontmatter (like companies.md, headlines.md) are data
files and get skipped.
"""

from __future__ import annotations

import logging
from dataclasses import dataclass, field
from pathlib import Path

import yaml

log = logging.getLogger(__name__)


@dataclass
class SkillDef:
    name: str
    description: str
    content: str
    file_path: Path
    tools: list[str] = field(default_factory=list)
    agents: list[str] = field(default_factory=list)


def _parse_frontmatter(text: str) -> tuple[dict, str]:
    """Split YAML frontmatter from markdown content.

    Returns (frontmatter_dict, body) or ({}, full_text) if no frontmatter.
    """
    if not text.startswith("---"):
        return {}, text

    end = text.find("---", 3)
    if end == -1:
        return {}, text

    yaml_block = text[3:end].strip()
    body = text[end + 3 :].strip()

    try:
        meta = yaml.safe_load(yaml_block) or {}
    except yaml.YAMLError as e:
        log.warning("Failed to parse YAML frontmatter: %s", e)
        return {}, text

    if not isinstance(meta, dict):
        return {}, text

    return meta, body


class SkillRegistry:
    """Discovers and holds markdown skill definitions."""

    def __init__(self, skills_dir: Path):
        self._skills: dict[str, SkillDef] = {}
        self._skills_dir = skills_dir
        self._discover()

    def _discover(self):
        """Load all .md files with valid frontmatter from the skills directory."""
        if not self._skills_dir.exists():
            log.warning("Skills directory not found: %s", self._skills_dir)
            return

        for path in sorted(self._skills_dir.glob("*.md")):
            try:
                text = path.read_text(encoding="utf-8")
            except Exception as e:
                log.warning("Failed to read skill file %s: %s", path.name, e)
                continue

            meta, body = _parse_frontmatter(text)
            if not meta.get("name"):
                # No frontmatter or no name — skip (data file)
                continue

            skill = SkillDef(
                name=meta["name"],
                description=meta.get("description", ""),
                content=body,
                file_path=path,
                tools=meta.get("tools", []),
                agents=meta.get("agents", []),
            )
            self._skills[skill.name] = skill
            log.info("Loaded skill: %s (%s)", skill.name, path.name)

    def get(self, name: str) -> SkillDef | None:
        return self._skills.get(name)

    def list_skills(self) -> list[SkillDef]:
        return list(self._skills.values())

    def get_prompt_section(self, agent_name: str = "default") -> str:
        """Build a prompt section with skills relevant to an agent.

        If a skill's agents list is empty, it's available to all agents.
        Otherwise, only agents listed in the skill's agents list get it.
        """
        parts = []
        for skill in self._skills.values():
            if skill.agents and agent_name not in skill.agents:
                continue
            parts.append(f"### Skill: {skill.name}\n{skill.description}\n")

        if not parts:
            return ""

        return "# Available Skills\n" + "\n".join(parts)

    def get_body(self, name: str) -> str:
        """Get the body content of a skill (without frontmatter)."""
        skill = self._skills.get(name)
        return skill.content if skill else ""