"""Skills manager — scans for and loads skill markdown files."""

from __future__ import annotations

import logging
from pathlib import Path

from pydantic import BaseModel

from app.models.config import SkillsConfig

logger = logging.getLogger(__name__)


class Skill(BaseModel):
    """Metadata for a discovered skill file."""

    name: str
    description: str
    path: Path


class SkillsManager:
    """Discovers, indexes, and loads skill files from configured directories."""

    def __init__(self, config: SkillsConfig, workspace_root: Path) -> None:
        self._config = config
        self._workspace = workspace_root
        self._skills: dict[str, Skill] = {}
        self._scan()

    def _scan(self) -> None:
        """Scan configured directories for .md skill files."""
        for skill_dir in self._config.directories:
            resolved = (self._workspace / skill_dir) if not skill_dir.is_absolute() else skill_dir
            if not resolved.is_dir():
                logger.debug("Skills directory does not exist: %s", resolved)
                continue
            for md in sorted(resolved.glob("*.md")):
                name = md.stem
                desc = self._extract_description(md)
                self._skills[name] = Skill(name=name, description=desc, path=md)
                logger.debug("Discovered skill: %s (%s)", name, desc)

    @staticmethod
    def _extract_description(path: Path) -> str:
        """Extract the first non-blank, non-heading line as the description."""
        for line in path.read_text().splitlines():
            stripped = line.strip()
            if stripped and not stripped.startswith("#"):
                return stripped
        return "(no description)"

    def list_skills(self) -> list[Skill]:
        """Return all discovered skills."""
        return list(self._skills.values())

    def load_skill(self, name: str) -> str | None:
        """Load the full content of a skill by name. Returns None if not found."""
        skill = self._skills.get(name)
        return skill.path.read_text() if skill else None

    def get_system_prompt_snippet(self) -> str:
        """Generate a snippet for the system prompt listing available skills."""
        if not self._skills:
            return ""
        lines = ["\nAvailable skills (invoke with /skill-name):"]
        for s in self._skills.values():
            lines.append(f"  - /{s.name}: {s.description}")
        lines.append("To use a skill's full instructions, call the load_skill tool.")
        return "\n".join(lines)