"""Mermaid MCP Server Integration.

Manages the external @peng-shawn/mermaid-mcp-server process for diagram generation.

Architecture:
    Garvis → (stdio) → mermaid-mcp-server (Node.js) → Puppeteer → PNG images
"""

import os
from pathlib import Path
from typing import Any, Dict, List
import yaml

_CONFIG_FILE = Path("config/mermaid_mcp.yaml")

def _load_config() -> Dict[str, Any]:
    """Load Mermaid MCP configuration from YAML and env vars."""
    config = {}
    if _CONFIG_FILE.exists():
        try:
            with open(_CONFIG_FILE, encoding="utf-8") as f:
                config = yaml.safe_load(f) or {}
        except Exception:
            pass  # Use defaults if config fails to load

    mermaid = config.get("mermaid_mcp", {})

    # Apply env var overrides
    if os.getenv("MERMAID_ENABLED"):
        mermaid["enabled"] = os.getenv("MERMAID_ENABLED").lower() in ("true", "1")
    if os.getenv("MERMAID_OUTPUT_DIR"):
        mermaid["output_dir"] = os.getenv("MERMAID_OUTPUT_DIR")
    if os.getenv("MERMAID_DEFAULT_FORMAT"):
        mermaid["default_format"] = os.getenv("MERMAID_DEFAULT_FORMAT")
    if os.getenv("MERMAID_THEME"):
        mermaid["theme"] = os.getenv("MERMAID_THEME")

    # Set defaults if not configured
    mermaid.setdefault("enabled", True)
    mermaid.setdefault("output_dir", "downloads/diagrams/mermaid")
    mermaid.setdefault("default_format", "png")
    mermaid.setdefault("theme", "default")

    return mermaid

def is_mermaid_enabled() -> bool:
    """Check if Mermaid MCP integration is enabled."""
    config = _load_config()
    return config.get("enabled", True)

def get_mermaid_server_config() -> Dict[str, Any]:
    """Build the MCP server configuration for Agent SDK registration.

    Returns:
        Dict with command, args, and env for subprocess execution
    """
    config = _load_config()
    output_dir = config.get("output_dir", "downloads/diagrams/mermaid")

    # Ensure output directory exists
    Path(output_dir).mkdir(parents=True, exist_ok=True)

    # Build environment variables for the MCP server
    env = {
        "PATH": os.environ.get("PATH", ""),
        "HOME": os.environ.get("HOME", os.environ.get("USERPROFILE", "")),
        "APPDATA": os.environ.get("APPDATA", ""),
        "TEMP": os.environ.get("TEMP", os.environ.get("TMP", "")),
    }

    # Add config as env vars for the server
    env["MERMAID_OUTPUT_DIR"] = str(Path(output_dir).absolute())
    env["MERMAID_DEFAULT_FORMAT"] = config.get("default_format", "png")
    env["MERMAID_THEME"] = config.get("theme", "default")

    return {
        "command": "npx",
        "args": ["-y", "@peng-shawn/mermaid-mcp-server"],
        "env": env,
    }

# Tool names exposed by mermaid-mcp-server
# Based on @peng-shawn/mermaid-mcp-server documentation
MERMAID_TOOLS: List[str] = [
    "render_mermaid",  # Main tool: convert Mermaid syntax to PNG
]