package api

import (
	"io/fs"
	"net/http"
	"strings"
)

// StaticHandler serves embedded SPA files with fallback to index.html
// for all non-API routes (SPA client-side routing support).
func StaticHandler(webFS fs.FS) http.Handler {
	fileServer := http.FileServer(http.FS(webFS))

	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Skip API routes — they are handled by the API router.
		if strings.HasPrefix(r.URL.Path, "/api") {
			http.NotFound(w, r)
			return
		}

		// Try to serve the exact file.
		path := strings.TrimPrefix(r.URL.Path, "/")
		if path == "" {
			path = "index.html"
		}

		// Check if file exists in the embedded FS.
		f, err := webFS.Open(path)
		if err == nil {
			f.Close()
			// Clear the JSON content-type set by middleware — let file server decide.
			w.Header().Del("Content-Type")
			fileServer.ServeHTTP(w, r)
			return
		}

		// File not found: serve index.html for SPA client-side routing.
		r.URL.Path = "/"
		w.Header().Del("Content-Type")
		fileServer.ServeHTTP(w, r)
	})
}