package server

import (
	"net/http"
	"path/filepath"

	"git.netflux.io/rob/clipper/config"
	"git.netflux.io/rob/clipper/filestore"
	"github.com/gorilla/mux"
	"github.com/improbable-eng/grpc-web/go/grpcweb"
	"go.uber.org/zap"
)

type httpHandler struct {
	grpcHandler     *grpcweb.WrappedGrpcServer
	router          http.Handler
	mediaSetService MediaSetService
	logger          *zap.SugaredLogger
}

func newHTTPHandler(grpcHandler *grpcweb.WrappedGrpcServer, mediaSetService MediaSetService, c config.Config, logger *zap.SugaredLogger) *httpHandler {
	fileStoreHandler := http.NotFoundHandler()
	if c.FileStoreHTTPRoot != "" {
		logger.With("root", c.FileStoreHTTPRoot, "baseURL", c.FileStoreHTTPBaseURL.String()).Info("Configured to serve file store over HTTP")
		fileStoreHandler = http.FileServer(&indexedFileSystem{http.Dir(c.FileStoreHTTPRoot)})
	}

	assetsHandler := http.NotFoundHandler()
	if c.AssetsHTTPRoot != "" {
		logger.With("root", c.AssetsHTTPRoot).Info("Configured to serve assets over HTTP")
		assetsHandler = http.FileServer(&indexedFileSystem{http.Dir(c.AssetsHTTPRoot)})
	}

	// If FileSystemStore AND assets serving are both enabled,
	// FileStoreHTTPBaseURL *must* be set to a value other than "/" to avoid
	// clobbering the assets routes.
	router := mux.NewRouter()
	if c.FileStore == config.FileSystemStore {
		router.
			Methods("GET").
			PathPrefix(c.FileStoreHTTPBaseURL.Path).
			Handler(filestore.NewFileSystemStoreHTTPMiddleware(c.FileStoreHTTPBaseURL, fileStoreHandler))
	}
	router.
		Methods("GET").
		Handler(assetsHandler)

	return &httpHandler{
		grpcHandler:     grpcHandler,
		router:          router,
		mediaSetService: mediaSetService,
		logger:          logger,
	}
}

func (h *httpHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if !h.grpcHandler.IsGrpcWebRequest(r) && !h.grpcHandler.IsAcceptableGrpcCorsRequest(r) {
		h.router.ServeHTTP(w, r)
		return
	}
	h.grpcHandler.ServeHTTP(w, r)
}

// indexedFileSystem is an HTTP file system which handles index.html files if
// they exist, but does not serve directory listings.
//
// Ref: https://www.alexedwards.net/blog/disable-http-fileserver-directory-listings
type indexedFileSystem struct {
	httpFS http.FileSystem
}

func (ifs *indexedFileSystem) Open(path string) (http.File, error) {
	f, err := ifs.httpFS.Open(path)
	if err != nil {
		return nil, err
	}

	s, err := f.Stat()
	if err != nil {
		return nil, err
	}
	if !s.IsDir() {
		return f, nil
	}

	index := filepath.Join(path, "index.html")
	if _, err := ifs.httpFS.Open(index); err != nil {
		_ = f.Close() // ignore error
		return nil, err
	}

	return f, nil
}