# Python backend for the Markdown View Plugin using FastAPI

import anyio  # For asynchronous file operations
from fastapi import FastAPI, HTTPException
from fastapi.responses import FileResponse
from fastapi.staticfiles import StaticFiles
from airflow.plugins_manager import AirflowPlugin
import importlib.resources as resources

# Use importlib.resources to locate static files and view.md
static_files_dir_ref = resources.files("markdown_view_plugin") / "ui" / "dist"
view_md_path_ref = resources.files("markdown_view_plugin") / "view.md"

# Create a FastAPI app
markdown_fastapi_app = FastAPI(
    title="Markdown View Plugin",
    description="A plugin to render Markdown content in Airflow UI.",
    version="1.0.0",
)

# Mount static files for the React UI
# The path "/static/markdown_view_plugin" must match the 'base' in ui/vite.config.ts
with resources.as_file(static_files_dir_ref) as static_files_dir:
    markdown_fastapi_app.mount(
        "/static/markdown_view_plugin",
        StaticFiles(directory=str(static_files_dir)),
        name="markdown_view_plugin_static",
    )

# API endpoint to get markdown content
@markdown_fastapi_app.get("/markdown_view/api/view")
async def get_markdown_content_api():
    """Asynchronously read and return the content of view.md."""
    with resources.as_file(view_md_path_ref) as view_md_path:
        try:
            async with await anyio.open_file(view_md_path) as f:
                content = await f.read()
            return {"markdown": content}
        except FileNotFoundError:
            raise HTTPException(status_code=404, detail="view.md not found")
        except Exception as e:
            raise HTTPException(status_code=500, detail=str(e))

# Endpoint to serve the main index.html of the React app
@markdown_fastapi_app.get("/markdown_view")
async def serve_markdown_ui():
    """Serve the main index.html for the plugin's UI."""
    with resources.as_file(static_files_dir_ref / "index.html") as index_html_path:
        if not index_html_path.exists():
            raise HTTPException(
                status_code=404,
                detail="index.html not found. Did you build the UI? (cd ui && pnpm run build)",
            )
        return FileResponse(str(index_html_path))

# Define the Airflow plugin
class MarkdownViewPlugin(AirflowPlugin):
    """
    Airflow Plugin for Markdown View.

    This plugin provides a FastAPI backend and a React frontend
    to display Markdown content within the Airflow UI.
    """

    name = "markdown_view_plugin"
    fastapi_apps = [
        {
            "app": markdown_fastapi_app,
            "name": "markdown_view_app",  # A unique name for this FastAPI app
            "app_mount": "/markdown_view_plugin_mount",
        }
    ]
    # Example menu link (optional, can also be configured via Airflow UI settings)
    menu_links = [
        {
            "name": "Markdown Viewer",
            "href": "/markdown_view_plugin_mount/markdown_view", # This should match the app_mount + @markdown_fastapi_app.get path for the UI
            "category": "Plugins",
        }
    ]

# For Airflow to pick up the plugin, the class name must match the filename (snake_case to PascalCase)
# or be explicitly defined in an __init__.py in the plugin\'s root directory.
# Assuming filename is markdown_view_plugin.py, class MarkdownViewPlugin is correct.