package update

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

// mockGitea поднимает httptest-сервер с бинарём, <filename>.version и .sha256.
func mockGitea(t *testing.T, bin []byte, version, checksum string) *httptest.Server {
	t.Helper()
	name := PlatformFilename()
	mux := http.NewServeMux()
	mux.HandleFunc("/api/packages/", func(w http.ResponseWriter, r *http.Request) {
		base := name
		switch {
		case strings.HasSuffix(r.URL.Path, ".version"):
			base = name + ".version"
			_, _ = w.Write([]byte(version))
		case strings.HasSuffix(r.URL.Path, ".sha256"):
			base = name + ".sha256"
			_, _ = w.Write([]byte(checksum))
		default:
			_, _ = w.Write(bin) // сам бинарь
		}
		_ = base
	})
	return httptest.NewServer(mux)
}

// testUpdater строит Updater с базой на мок-сервере и каталогом tmp.
func testUpdater(t *testing.T, bin []byte, version, cur string) (*Updater, string) {
	t.Helper()
	sum := sha256hex(bin)
	srv := mockGitea(t, bin, version, sum)
	t.Cleanup(srv.Close)
	dir := t.TempDir()
	u := &Updater{
		BaseURL:        srv.URL,
		Owner:          "kamelion",
		Package:        "ratatoskr",
		CurrentVersion: cur,
		Dir:            dir,
	}
	return u, dir
}

func TestFilename(t *testing.T) {
	cases := []struct{ goos, goarch, want string }{
		{"linux", "amd64", "ratatoskr-linux-amd64"},
		{"linux", "arm64", "ratatoskr-linux-arm64"},
		{"darwin", "arm64", "ratatoskr-darwin-arm64"},
		{"windows", "amd64", "ratatoskr-windows-amd64.exe"},
	}
	for _, c := range cases {
		if got := Filename(c.goos, c.goarch); got != c.want {
			t.Errorf("Filename(%s,%s)=%q want %q", c.goos, c.goarch, got, c.want)
		}
	}
}

func TestCheck_UpdateAvailable(t *testing.T) {
	u, _ := testUpdater(t, []byte("bin"), "commit-abc1234", "commit-old0000")
	res := u.Check(context.Background())
	if res.Err != nil {
		t.Fatalf("Check err = %v", res.Err)
	}
	if !res.UpdateAvailable {
		t.Fatal("expected update available")
	}
	if res.Version != "commit-abc1234" {
		t.Errorf("Version = %q want commit-abc1234", res.Version)
	}
}

func TestCheck_AlreadyCurrent(t *testing.T) {
	u, _ := testUpdater(t, []byte("bin"), "commit-abc1234", "commit-abc1234")
	res := u.Check(context.Background())
	if res.Err != nil {
		t.Fatalf("Check err = %v", res.Err)
	}
	if res.UpdateAvailable {
		t.Fatal("not expected update (same version)")
	}
}

func TestCheck_ServerDown(t *testing.T) {
	dir := t.TempDir()
	u := &Updater{BaseURL: "http://127.0.0.1:1", Owner: "k", Package: "p", CurrentVersion: "v1", Dir: dir}
	res := u.Check(context.Background())
	if res.Err == nil {
		t.Fatal("expected error for unreachable server")
	}
	// ошибка должна классифицироваться как U1 ErrCheckFailed
	var uerr *Error
	if !errorsAs(res.Err, &uerr) || uerr.Code != U1 {
		t.Errorf("expected U1 error, got %v", res.Err)
	}
}

func TestDownload_And_Verify_Good(t *testing.T) {
	bin := []byte("ratatoskr-binary-content-v2")
	u, dir := testUpdater(t, bin, "commit-new12345", "")
	file, err := u.Download(context.Background(), "commit-new12345")
	if err != nil {
		t.Fatalf("Download err = %v", err)
	}
	if !strings.Contains(file, ".new") {
		t.Errorf("temp file %q should end with .new", filepath.Base(file))
	}
	if err := u.Verify(context.Background(), file); err != nil {
		t.Fatalf("Verify err = %v", err)
	}
	// .new лежит в каталоге
	entries, _ := os.ReadDir(dir)
	if len(entries) != 1 || !strings.HasSuffix(entries[0].Name(), ".new") {
		t.Errorf("expected 1 .new file in dir, got %v", entries)
	}
}

func TestVerify_ChecksumMismatch(t *testing.T) {
	bin := []byte("A")
	srv := mockGitea(t, bin, "commit-x", sha256hex([]byte("differente-content")))
	t.Cleanup(srv.Close)
	u := &Updater{BaseURL: srv.URL, Owner: "k", Package: "p", Dir: t.TempDir()}
	file := filepath.Join(u.Dir, ".ratatoskr.x.new")
	if err := os.WriteFile(file, []byte("A"), 0o755); err != nil {
		t.Fatal(err)
	}
	err := u.Verify(context.Background(), file)
	if err == nil {
		t.Fatal("expected checksum mismatch error")
	}
	var uerr *Error
	if !errorsAs(err, &uerr) || uerr.Code != U4 {
		t.Errorf("expected U4 error, got %v", err)
	}
}

func TestSanitizeVer(t *testing.T) {
	cases := map[string]string{
		"commit-abc1234": "commit-abc1234",
		"v1.2.3":         "v1.2.3",
		"a/b c":          "a_b_c",
		"":               "unknown",
	}
	for in, want := range cases {
		if got := sanitizeVer(in); got != want {
			t.Errorf("sanitizeVer(%q)=%q want %q", in, got, want)
		}
	}
}

func TestApplySwap_NoPending(t *testing.T) {
	dir := t.TempDir()
	u := &Updater{Dir: dir}
	if err := u.applySwap(dir, filepath.Join(dir, "ratatoskr")); err != nil {
		t.Fatalf("applySwap with no .new should return nil, got %v", err)
	}
}

func TestApplySwap_Applies(t *testing.T) {
	dir := t.TempDir()
	exe := filepath.Join(dir, "ratatoskr")
	if err := os.WriteFile(exe, []byte("old"), 0o755); err != nil {
		t.Fatal(err)
	}
	newFile := filepath.Join(dir, ".ratatoskr.commit-n.new")
	if err := os.WriteFile(newFile, []byte("new-content"), 0o755); err != nil {
		t.Fatal(err)
	}
	u := &Updater{Dir: dir}
	if err := u.applySwap(dir, exe); err != nil {
		t.Fatalf("applySwap err = %v", err)
	}
	got, _ := os.ReadFile(exe)
	if string(got) != "new-content" {
		t.Errorf("exe content = %q want new-content", got)
	}
	// старый бэкап в .old
	old, _ := os.ReadFile(filepath.Join(dir, CrashSafeTag))
	if string(old) != "old" {
		t.Errorf(".old content = %q want old", old)
	}
}

func TestErrorsAs(t *testing.T) {
	// проверка классификатора через errorsAs на Error(U4)
	err := ue(U4, "verify", os.ErrPermission)
	var uerr *Error
	if !errorsAs(err, &uerr) {
		t.Fatal("errorsAs failed to unwrap *Error")
	}
	if uerr.Code != U4 {
		t.Errorf("code = %v want U4", uerr.Code)
	}
	if !errors.Is(err, os.ErrPermission) {
		t.Errorf("errors.Is(err, ErrPermission) = false, want true")
	}
}

// errorsAs — тонкая обёртка errors.As для классификатора update.Error.
func errorsAs(err error, target **Error) bool {
	type causer interface{ Unwrap() error }
	for err != nil {
		if e, ok := err.(*Error); ok {
			*target = e
			return true
		}
		c, ok := err.(causer)
		if !ok {
			return false
		}
		err = c.Unwrap()
	}
	return false
}