package main

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"reflect"
	"testing"
	"testing/fstest"
)

func musicServer(t *testing.T) (*httptest.Server, string) {
	t.Helper()
	dir := t.TempDir()
	write := func(name, content string) {
		if err := os.WriteFile(filepath.Join(dir, name), []byte(content), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	write("b_second.MP3", "not really audio, but not empty")
	write("a_first.mp3", "0123456789")
	write("placeholder.mp3", "") // the empty placeholder must not be offered
	write("notes.txt", "hello")
	write(".hidden.mp3", "secret")
	if err := os.Mkdir(filepath.Join(dir, "sub"), 0o755); err != nil {
		t.Fatal(err)
	}
	site := fstest.MapFS{"index.html": {Data: []byte("<h1>game</h1>")}}
	return httptest.NewServer(newMux(site, dir)), dir
}

func get(t *testing.T, url string, header ...string) (*http.Response, string) {
	t.Helper()
	req, _ := http.NewRequest("GET", url, nil)
	for i := 0; i+1 < len(header); i += 2 {
		req.Header.Set(header[i], header[i+1])
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	buf := make([]byte, 4096)
	n, _ := resp.Body.Read(buf)
	return resp, string(buf[:n])
}

func TestMusicFolder(t *testing.T) {
	srv, _ := musicServer(t)
	defer srv.Close()

	// the index offers only real, non-empty mp3 files, sorted
	resp, body := get(t, srv.URL+"/music/index.json")
	var idx struct{ Tracks []string }
	if err := json.Unmarshal([]byte(body), &idx); err != nil {
		t.Fatalf("index.json: %v (%s)", err, body)
	}
	if want := []string{"a_first.mp3", "b_second.MP3"}; !reflect.DeepEqual(idx.Tracks, want) {
		t.Errorf("tracks = %v, want %v", idx.Tracks, want)
	}
	if resp.Header.Get("Cache-Control") != "no-store" {
		t.Error("the index must not be cached: tracks are added without a rebuild")
	}

	// a track is served, and byte ranges work (the browser needs them to seek)
	if r, b := get(t, srv.URL+"/music/a_first.mp3"); r.StatusCode != 200 || b != "0123456789" {
		t.Errorf("track: %d %q", r.StatusCode, b)
	}
	if r, b := get(t, srv.URL+"/music/a_first.mp3", "Range", "bytes=2-4"); r.StatusCode != 206 || b != "234" {
		t.Errorf("range: %d %q", r.StatusCode, b)
	}

	// nothing else leaks: no listing, no dot files, no sub folders, no way out of the folder
	for _, path := range []string{"/music/", "/music/.hidden.mp3", "/music/sub", "/music/..%2Fmain.go", "/music/%2e%2e/main.go"} {
		if r, _ := get(t, srv.URL+path); r.StatusCode == 200 {
			t.Errorf("%s must not be served", path)
		}
	}
	// the game itself is still served
	if r, b := get(t, srv.URL+"/"); r.StatusCode != 200 || b != "<h1>game</h1>" {
		t.Errorf("site: %d %q", r.StatusCode, b)
	}
}

func TestMusicFolderMissing(t *testing.T) {
	srv := httptest.NewServer(newMux(fstest.MapFS{}, filepath.Join(t.TempDir(), "nope")))
	defer srv.Close()
	resp, body := get(t, srv.URL+"/music/index.json")
	if resp.StatusCode != 200 || body != "{\"tracks\":[]}\n" {
		t.Errorf("a missing music folder should give an empty list, got %d %q", resp.StatusCode, body)
	}
}