"""Skills loader for agent capabilities."""

import json
import os
import re
import shutil
from pathlib import Path

# Default builtin skills directory (relative to this file)
BUILTIN_SKILLS_DIR = Path(__file__).parent.parent / "skills"
AGNO_ALLOWED_FRONTMATTER_FIELDS = {
    "allowed-tools",
    "compatibility",
    "description",
    "license",
    "metadata",
    "name",
}


def _sanitize_skill_frontmatter(content: str) -> str:
    """Keep only agno-supported frontmatter fields."""
    if not content.startswith("---\n"):
        return content

    match = re.match(r"^---\n(.*?)\n---\n?", content, re.DOTALL)
    if not match:
        return content

    frontmatter = match.group(1)
    body = content[match.end():]
    kept_lines: list[str] = []
    for line in frontmatter.splitlines():
        if ":" not in line:
            continue
        key, value = line.split(":", 1)
        if key.strip() in AGNO_ALLOWED_FRONTMATTER_FIELDS:
            kept_lines.append(f"{key.strip()}:{value}")

    if not kept_lines:
        return body
    return "---\n" + "\n".join(kept_lines) + "\n---\n" + body


def _prepare_agno_skills_dir(source_dir: Path, target_dir: Path) -> Path:
    """Copy skills and sanitize SKILL.md frontmatter for agno."""
    if target_dir.exists():
        shutil.rmtree(target_dir)
    target_dir.mkdir(parents=True, exist_ok=True)

    for skill_dir in source_dir.iterdir():
        if not skill_dir.is_dir():
            continue
        skill_file = skill_dir / "SKILL.md"
        if not skill_file.exists():
            continue

        dst_dir = target_dir / skill_dir.name
        shutil.copytree(skill_dir, dst_dir, dirs_exist_ok=True)
        dst_skill_file = dst_dir / "SKILL.md"
        raw = dst_skill_file.read_text(encoding="utf-8")
        dst_skill_file.write_text(_sanitize_skill_frontmatter(raw), encoding="utf-8")

    return target_dir


def build_agno_skills(workspace: Path):
    """
    Build agno Skills from local skill directories.

    Priority:
    1) Workspace skills: <workspace>/skills
    2) Built-in skills: asedclaw/skills
    """
    try:
        from agno.skills import LocalSkills, Skills
    except Exception:
        return None

    loaders = []
    cache_root = workspace / ".asedclaw" / "agno_skills_cache"
    workspace_skills = workspace / "skills"
    try:
        if workspace_skills.exists() and workspace_skills.is_dir():
            sanitized_workspace = _prepare_agno_skills_dir(
                workspace_skills, cache_root / "workspace"
            )
            loaders.append(LocalSkills(str(sanitized_workspace)))

        if BUILTIN_SKILLS_DIR.exists() and BUILTIN_SKILLS_DIR.is_dir():
            sanitized_builtin = _prepare_agno_skills_dir(
                BUILTIN_SKILLS_DIR, cache_root / "builtin"
            )
            loaders.append(LocalSkills(str(sanitized_builtin)))
    except Exception:
        # Best-effort fallback: use original directories directly.
        if workspace_skills.exists() and workspace_skills.is_dir():
            loaders.append(LocalSkills(str(workspace_skills)))
        if BUILTIN_SKILLS_DIR.exists() and BUILTIN_SKILLS_DIR.is_dir():
            loaders.append(LocalSkills(str(BUILTIN_SKILLS_DIR)))

    if not loaders:
        return None
    try:
        return Skills(loaders=loaders)
    except Exception:
        return None


class SkillsLoader:
    """
    Loader for agent skills.

    Skills are markdown files (SKILL.md) that teach the agent how to use
    specific tools or perform certain tasks.
    """

    def __init__(self, workspace: Path, builtin_skills_dir: Path | None = None):
        self.workspace = workspace
        self.workspace_skills = workspace / "skills"
        self.builtin_skills = builtin_skills_dir or BUILTIN_SKILLS_DIR

    def list_skills(self, filter_unavailable: bool = True) -> list[dict[str, str]]:
        """
        List all available skills.

        Args:
            filter_unavailable: If True, filter out skills with unmet requirements.

        Returns:
            List of skill info dicts with 'name', 'path', 'source'.
        """
        skills = []

        # Workspace skills (highest priority)
        if self.workspace_skills.exists():
            for skill_dir in self.workspace_skills.iterdir():
                if skill_dir.is_dir():
                    skill_file = skill_dir / "SKILL.md"
                    if skill_file.exists():
                        skills.append({"name": skill_dir.name, "path": str(skill_file), "source": "workspace"})

        # Built-in skills
        if self.builtin_skills and self.builtin_skills.exists():
            for skill_dir in self.builtin_skills.iterdir():
                if skill_dir.is_dir():
                    skill_file = skill_dir / "SKILL.md"
                    if skill_file.exists() and not any(s["name"] == skill_dir.name for s in skills):
                        skills.append({"name": skill_dir.name, "path": str(skill_file), "source": "builtin"})

        # Filter by requirements
        if filter_unavailable:
            return [s for s in skills if self._check_requirements(self._get_skill_meta(s["name"]))]
        return skills

    def load_skill(self, name: str) -> str | None:
        """
        Load a skill by name.

        Args:
            name: Skill name (directory name).

        Returns:
            Skill content or None if not found.
        """
        # Check workspace first
        workspace_skill = self.workspace_skills / name / "SKILL.md"
        if workspace_skill.exists():
            return workspace_skill.read_text(encoding="utf-8")

        # Check built-in
        if self.builtin_skills:
            builtin_skill = self.builtin_skills / name / "SKILL.md"
            if builtin_skill.exists():
                return builtin_skill.read_text(encoding="utf-8")

        return None

    def load_skills_for_context(self, skill_names: list[str]) -> str:
        """
        Load specific skills for inclusion in agent context.

        Args:
            skill_names: List of skill names to load.

        Returns:
            Formatted skills content.
        """
        parts = []
        for name in skill_names:
            content = self.load_skill(name)
            if content:
                content = self._strip_frontmatter(content)
                parts.append(f"### Skill: {name}\n\n{content}")

        return "\n\n---\n\n".join(parts) if parts else ""

    def build_skills_summary(self) -> str:
        """
        Build a summary of all skills (name, description, path, availability).

        This is used for progressive loading - the agent can read the full
        skill content using read_file when needed.

        Returns:
            XML-formatted skills summary.
        """
        all_skills = self.list_skills(filter_unavailable=False)
        if not all_skills:
            return ""

        def escape_xml(s: str) -> str:
            return s.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")

        lines = ["<skills>"]
        for s in all_skills:
            name = escape_xml(s["name"])
            path = s["path"]
            desc = escape_xml(self._get_skill_description(s["name"]))
            skill_meta = self._get_skill_meta(s["name"])
            available = self._check_requirements(skill_meta)

            lines.append(f"  <skill available=\"{str(available).lower()}\">")
            lines.append(f"    <name>{name}</name>")
            lines.append(f"    <description>{desc}</description>")
            lines.append(f"    <location>{path}</location>")

            # Show missing requirements for unavailable skills
            if not available:
                missing = self._get_missing_requirements(skill_meta)
                if missing:
                    lines.append(f"    <requires>{escape_xml(missing)}</requires>")

            lines.append("  </skill>")
        lines.append("</skills>")

        return "\n".join(lines)

    def _get_missing_requirements(self, skill_meta: dict) -> str:
        """Get a description of missing requirements."""
        missing = []
        requires = skill_meta.get("requires", {})
        for b in requires.get("bins", []):
            if not shutil.which(b):
                missing.append(f"CLI: {b}")
        for env in requires.get("env", []):
            if not os.environ.get(env):
                missing.append(f"ENV: {env}")
        return ", ".join(missing)

    def _get_skill_description(self, name: str) -> str:
        """Get the description of a skill from its frontmatter."""
        meta = self.get_skill_metadata(name)
        if meta and meta.get("description"):
            return meta["description"]
        return name  # Fallback to skill name

    def _strip_frontmatter(self, content: str) -> str:
        """Remove YAML frontmatter from markdown content."""
        if content.startswith("---"):
            match = re.match(r"^---\n.*?\n---\n", content, re.DOTALL)
            if match:
                return content[match.end():].strip()
        return content

    def _parse_nanobot_metadata(self, raw: str) -> dict:
        """Parse skill metadata JSON from frontmatter (supports asedclaw and openclaw keys)."""
        try:
            data = json.loads(raw)
            return data.get("asedclaw", data.get("openclaw", {})) if isinstance(data, dict) else {}
        except (json.JSONDecodeError, TypeError):
            return {}

    def _check_requirements(self, skill_meta: dict) -> bool:
        """Check if skill requirements are met (bins, env vars)."""
        requires = skill_meta.get("requires", {})
        for b in requires.get("bins", []):
            if not shutil.which(b):
                return False
        for env in requires.get("env", []):
            if not os.environ.get(env):
                return False
        return True

    def _get_skill_meta(self, name: str) -> dict:
        """Get asedclaw metadata for a skill (cached in frontmatter)."""
        meta = self.get_skill_metadata(name) or {}
        return self._parse_nanobot_metadata(meta.get("metadata", ""))

    def get_always_skills(self) -> list[str]:
        """Get skills marked as always=true that meet requirements."""
        result = []
        for s in self.list_skills(filter_unavailable=True):
            meta = self.get_skill_metadata(s["name"]) or {}
            skill_meta = self._parse_nanobot_metadata(meta.get("metadata", ""))
            if skill_meta.get("always") or meta.get("always"):
                result.append(s["name"])
        return result

    def get_skill_metadata(self, name: str) -> dict | None:
        """
        Get metadata from a skill's frontmatter.

        Args:
            name: Skill name.

        Returns:
            Metadata dict or None.
        """
        content = self.load_skill(name)
        if not content:
            return None

        if content.startswith("---"):
            match = re.match(r"^---\n(.*?)\n---", content, re.DOTALL)
            if match:
                # Simple YAML parsing
                metadata = {}
                for line in match.group(1).split("\n"):
                    if ":" in line:
                        key, value = line.split(":", 1)
                        metadata[key.strip()] = value.strip().strip('"\'')
                return metadata

        return None
