package userscript

import (
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

const testToken = "s3cret-token"

// sampleScript is a stand-in for the real userscript: a metadata block with a
// @version line, plus a body that must survive the rewrite untouched.
const sampleScript = `// ==UserScript==
// @name         Manga Bookmark Sync
// @version      1.5.0
// @match        https://asurascans.com/*
// ==/UserScript==
(function () { "use strict"; })();
`

// writeScript drops a userscript in a temp dir with a known mtime and returns
// its path plus the version string the handler is expected to stamp.
func writeScript(t *testing.T, body string) (path, wantVersion string) {
	t.Helper()
	path = filepath.Join(t.TempDir(), "manga-bookmark.user.js")
	if err := os.WriteFile(path, []byte(body), 0o644); err != nil {
		t.Fatalf("write script: %v", err)
	}
	mod := time.Date(2026, 7, 28, 16, 42, 0, 0, time.UTC)
	if err := os.Chtimes(path, mod, mod); err != nil {
		t.Fatalf("chtimes: %v", err)
	}
	return path, "2026.07.28.1642"
}

// newTestMux registers Handler the same way main.go's router does, without
// pulling in the store or the rest of the app.
func newTestMux(token, path string) http.Handler {
	mux := http.NewServeMux()
	mux.HandleFunc("GET /u/{token}/manga-bookmark.user.js", Handler(token, path))
	return mux
}

func getScript(t *testing.T, srv http.Handler, token string) *httptest.ResponseRecorder {
	t.Helper()
	rr := httptest.NewRecorder()
	srv.ServeHTTP(rr, httptest.NewRequest(http.MethodGet, "/u/"+token+"/manga-bookmark.user.js", nil))
	return rr
}

func TestUserscriptServedWithStampedVersion(t *testing.T) {
	path, wantVersion := writeScript(t, sampleScript)
	rr := getScript(t, newTestMux(testToken, path), testToken)

	if rr.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", rr.Code)
	}
	if ct := rr.Header().Get("Content-Type"); !strings.HasPrefix(ct, "text/javascript") {
		t.Errorf("Content-Type = %q, want text/javascript", ct)
	}
	if cc := rr.Header().Get("Cache-Control"); cc != "no-cache" {
		t.Errorf("Cache-Control = %q, want no-cache", cc)
	}
	body := rr.Body.String()
	if !strings.Contains(body, "// @version      "+wantVersion) {
		t.Errorf("body has no stamped version %q:\n%s", wantVersion, body)
	}
	if strings.Contains(body, "1.5.0") {
		t.Errorf("body still carries the file's own version:\n%s", body)
	}
	// Everything outside the @version line is served verbatim.
	if !strings.Contains(body, `(function () { "use strict"; })();`) {
		t.Errorf("body was altered beyond the version line:\n%s", body)
	}
	if !strings.Contains(body, "// @name         Manga Bookmark Sync") {
		t.Errorf("metadata block was altered:\n%s", body)
	}
}

// The empty-token case ("/u//manga-bookmark.user.js") is covered at the
// router level (see backend's guardEmptyUserscriptToken): ServeMux 307s it to
// "/u/manga-bookmark.user.js" before this handler's own token check ever runs.
func TestUserscriptWrongTokenIs404(t *testing.T) {
	path, _ := writeScript(t, sampleScript)
	srv := newTestMux(testToken, path)
	for _, tok := range []string{"wrong", testToken + "x", testToken[:3]} {
		if got := getScript(t, srv, tok).Code; got != http.StatusNotFound {
			t.Errorf("token %q: status = %d, want 404", tok, got)
		}
	}
}

func TestUserscriptMissingFileIs404(t *testing.T) {
	srv := newTestMux(testToken, filepath.Join(t.TempDir(), "absent.user.js"))
	if got := getScript(t, srv, testToken).Code; got != http.StatusNotFound {
		t.Fatalf("status = %d, want 404", got)
	}
}

func TestUserscriptWithoutVersionLineServedUnmodified(t *testing.T) {
	const noVersion = "// ==UserScript==\n// @name x\n// ==/UserScript==\nconsole.log(1);\n"
	path, _ := writeScript(t, noVersion)
	rr := getScript(t, newTestMux(testToken, path), testToken)

	if rr.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", rr.Code)
	}
	if rr.Body.String() != noVersion {
		t.Fatalf("body = %q, want it unmodified", rr.Body.String())
	}
}