package docsite

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

func TestServeAddrPolicy(t *testing.T) {
	for _, tc := range []struct {
		addr        string
		allowRemote bool
		want        string // "" accepts; otherwise an error substring
	}{
		{"127.0.0.1:8088", false, ""},
		{"127.0.0.2:0", false, ""},
		{"[::1]:8088", false, ""},
		{"localhost:8088", false, ""},
		{"0.0.0.0:8088", false, "not a loopback address"},
		{"[::]:8088", false, "not a loopback address"},
		{"192.168.1.10:8088", false, "not a loopback address"},
		{"docs.example.com:8088", false, "not a loopback address"},
		{":8088", false, "not a loopback address"},
		{"0.0.0.0:8088", true, ""},
		{"[::]:8088", true, ""},
		{"docs.example.com:8088", true, ""},
		{"127.0.0.1", false, "invalid --addr"},
		{"127.0.0.1", true, "invalid --addr"},
	} {
		err := checkServeAddr(tc.addr, tc.allowRemote)
		if (tc.want == "") != (err == nil) || (err != nil && !strings.Contains(err.Error(), tc.want)) {
			t.Errorf("checkServeAddr(%q, %v) = %v, want %q", tc.addr, tc.allowRemote, err, tc.want)
		}
	}
	if DefaultServeAddr != "127.0.0.1:8088" || checkServeAddr(DefaultServeAddr, false) != nil {
		t.Errorf("DefaultServeAddr %s must be loopback", DefaultServeAddr)
	}
}

func TestServeHandlerBranches(t *testing.T) {
	out := buildTheme(t)
	if err := os.MkdirAll(filepath.Join(out, "nested", "dir"), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(out, "nested", "index.html"), []byte("nested index"), 0o644); err != nil {
		t.Fatal(err)
	}
	srv := httptest.NewServer(Handler(out))
	defer srv.Close()
	do := func(method, p string) (*http.Response, string) {
		t.Helper()
		req, err := http.NewRequest(method, srv.URL+p, nil)
		if err != nil {
			t.Fatal(err)
		}
		res, err := http.DefaultClient.Do(req)
		if err != nil {
			t.Fatal(err)
		}
		defer res.Body.Close()
		body, _ := io.ReadAll(res.Body)
		return res, string(body)
	}
	if res, body := do(http.MethodGet, "/nested/"); res.StatusCode != http.StatusOK || body != "nested index" {
		t.Errorf("GET /nested/ = %d %q", res.StatusCode, body)
	}
	if res, body := do(http.MethodHead, "/index.html"); res.StatusCode != http.StatusOK || body != "" {
		t.Errorf("HEAD /index.html = %d %q", res.StatusCode, body)
	}
	for _, p := range []string{"/nested/dir/", "/.hidden/x", "/assets/.x.css", "/nope"} {
		res, body := do(http.MethodGet, p)
		if res.StatusCode != http.StatusNotFound || !strings.Contains(body, "Page not found") ||
			!strings.HasPrefix(res.Header.Get("Content-Type"), "text/html") {
			t.Errorf("GET %s = %d %q", p, res.StatusCode, res.Header.Get("Content-Type"))
		}
	}
	for _, m := range []string{http.MethodPost, http.MethodPut, http.MethodDelete} {
		res, _ := do(m, "/index.html")
		if res.StatusCode != http.StatusMethodNotAllowed || res.Header.Get("Allow") != "GET, HEAD" {
			t.Errorf("%s = %d Allow=%q", m, res.StatusCode, res.Header.Get("Allow"))
		}
	}

	// Without a 404.html the handler still answers 404.
	bare := httptest.NewServer(Handler(t.TempDir()))
	defer bare.Close()
	res, err := http.Get(bare.URL + "/missing")
	if err != nil {
		t.Fatal(err)
	}
	res.Body.Close()
	if res.StatusCode != http.StatusNotFound {
		t.Errorf("bare 404 = %d", res.StatusCode)
	}
}

func TestServeRebuildKeepsLastGoodBuild(t *testing.T) {
	root := themeTree(t)
	out := &syncBuffer{}
	s := &server{opts: Options{Root: root, Commands: fixtureCommands}, tmp: t.TempDir(), out: out}
	s.opts, _ = s.opts.normalize()
	if !s.rebuild() {
		t.Fatalf("first build failed: %s", out.String())
	}
	first := s.dir()
	if filepath.Base(first) != "build-1" {
		t.Fatalf("first build dir = %s", first)
	}

	// A problem keeps the previous build and says so.
	index := filepath.Join(root, "docs", "index.md")
	good, err := os.ReadFile(index)
	if err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(index, append(append([]byte{}, good...), "\nSee `summer no:such`.\n"...), 0o644); err != nil {
		t.Fatal(err)
	}
	if s.rebuild() {
		t.Fatal("rebuild accepted a planted problem")
	}
	if s.dir() != first {
		t.Fatalf("serving %s after a failed build, want %s", s.dir(), first)
	}
	for _, want := range []string{`command: "no:such" is not a summer or application command`, "docs:serve: build failed, still serving the previous version"} {
		if !strings.Contains(out.String(), want) {
			t.Errorf("output missing %q:\n%s", want, out.String())
		}
	}
	if _, err := os.Stat(filepath.Join(s.tmp, "build-2")); !errors.Is(err, os.ErrNotExist) {
		t.Error("the failed build directory was kept")
	}

	// A load error is printed too.
	site := filepath.Join(root, "docs", "site.yaml")
	cfg, err := os.ReadFile(site)
	if err != nil {
		t.Fatal(err)
	}
	if err := os.Remove(site); err != nil {
		t.Fatal(err)
	}
	if s.rebuild() || !strings.Contains(out.String(), "read site config") {
		t.Fatalf("rebuild without site.yaml: %s", out.String())
	}
	if err := os.WriteFile(site, cfg, 0o644); err != nil {
		t.Fatal(err)
	}

	// Two good builds later the first directory is gone; the one before
	// the current build is kept for in-flight requests.
	if err := os.WriteFile(index, good, 0o644); err != nil {
		t.Fatal(err)
	}
	if !s.rebuild() || !s.rebuild() {
		t.Fatalf("rebuilds failed: %s", out.String())
	}
	if _, err := os.Stat(first); !errors.Is(err, os.ErrNotExist) {
		t.Errorf("%s survived two newer builds", first)
	}
	if _, err := os.Stat(s.stale); err != nil {
		t.Errorf("the previous build %s was removed early", s.stale)
	}
	if _, err := os.Stat(filepath.Join(s.dir(), "index.html")); err != nil {
		t.Error(err)
	}
}

func TestServeStartupFailures(t *testing.T) {
	// A tree with a problem never starts serving.
	root := themeTree(t)
	appendFile(t, root, "docs/index.md", "\n`summer no:such`\n")
	var out syncBuffer
	err := Serve(context.Background(), Options{Root: root, Commands: fixtureCommands}, "127.0.0.1:0", false, &out)
	if err == nil || err.Error() != "docs:serve: build failed" {
		t.Fatalf("Serve with a problem = %v", err)
	}
	if strings.Contains(out.String(), "still serving") || !strings.Contains(out.String(), "no:such") {
		t.Errorf("output = %s", out.String())
	}

	// A taken address is reported.
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	defer ln.Close()
	err = Serve(context.Background(), Options{Root: themeTree(t), Commands: fixtureCommands}, ln.Addr().String(), false, &out)
	if err == nil || !strings.HasPrefix(err.Error(), "docs:serve: ") {
		t.Fatalf("Serve on a taken address = %v", err)
	}
}

// TestServeWatchRebuilds edits a page while Serve runs and waits for the
// new build, then plants a problem and checks the old build stays up.
func TestServeWatchRebuilds(t *testing.T) {
	root := themeTree(t)
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	out := &syncBuffer{}
	done := make(chan error, 1)
	go func() { done <- Serve(ctx, Options{Root: root, Commands: fixtureCommands}, "127.0.0.1:0", false, out) }()
	waitFor := func(what string, cond func() bool) {
		t.Helper()
		for deadline := time.Now().Add(20 * time.Second); time.Now().Before(deadline); time.Sleep(20 * time.Millisecond) {
			if cond() {
				return
			}
		}
		t.Fatalf("timed out waiting for %s; output:\n%s", what, out.String())
	}
	var base string
	waitFor("the serving line", func() bool {
		if m := servingLine.FindStringSubmatch(out.String()); m != nil {
			base = m[1]
			return true
		}
		return false
	})
	get := func(p string) string {
		t.Helper()
		res, err := http.Get(base + p)
		if err != nil {
			t.Fatal(err)
		}
		defer res.Body.Close()
		b, _ := io.ReadAll(res.Body)
		return string(b)
	}

	// A dot-file change is ignored; a page edit rebuilds.
	writeFile(t, root, "docs/.scratch", "x")
	appendFile(t, root, "docs/setup/second.md", "\nFreshly edited.\n")
	waitFor("a rebuild", func() bool { return strings.Contains(out.String(), "docs:serve: rebuilt") })
	waitFor("the edited page", func() bool { return strings.Contains(get("/setup/second.html"), "Freshly edited.") })

	// A new page rebuilds and is served.
	writeFile(t, root, "docs/setup/third.md", page("Third", "setup", 90, "Brand new.\n"))
	waitFor("the new page", func() bool { return strings.Contains(get("/setup/third.html"), "Brand new.") })

	// A planted problem keeps the last good build online.
	appendFile(t, root, "docs/setup/second.md", "\n`summer no:such`\n")
	waitFor("the failed rebuild", func() bool { return strings.Contains(out.String(), "still serving the previous version") })
	if !strings.Contains(get("/setup/second.html"), "Freshly edited.") {
		t.Error("the last good build is no longer served")
	}

	cancel()
	select {
	case err := <-done:
		if err != nil {
			t.Fatalf("Serve = %v after cancel", err)
		}
	case <-time.After(10 * time.Second):
		t.Fatal("Serve did not return after cancel")
	}
}