package web

import (
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"testing/fstest"

	"khosra/internal/content"
	"khosra/internal/render"
)

func testHandler(t *testing.T) http.Handler {
	t.Helper()
	fsys := fstest.MapFS{
		"content/pages/about.md":       {Data: []byte("---\ntitle: About\n---\nAbout me.\n")},
		"content/posts/hello/index.md": {Data: []byte("---\ntitle: Hello\n---\nFirst post.\n")},
	}
	bundles, err := content.Scan(fsys)
	if err != nil {
		t.Fatal(err)
	}
	r, err := render.New()
	if err != nil {
		t.Fatal(err)
	}
	return Handler(content.NewSite(bundles), r)
}

func TestServeBundleAtItsPermalink(t *testing.T) {
	h := testHandler(t)
	for _, path := range []string{"/pages/about/", "/posts/hello/"} {
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, path, nil))
		if rec.Code != http.StatusOK {
			t.Fatalf("GET %s = %d, want 200", path, rec.Code)
		}
		if ct := rec.Header().Get("Content-Type"); !strings.HasPrefix(ct, "text/html") {
			t.Errorf("GET %s content-type = %q", path, ct)
		}
	}
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/pages/about/", nil))
	if body := rec.Body.String(); !strings.Contains(body, "<h1>About</h1>") || !strings.Contains(body, "About me.") {
		t.Errorf("body did not render the bundle:\n%s", body)
	}
}

func TestSlashlessPathRedirectsPermanently(t *testing.T) {
	h := testHandler(t)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/pages/about", nil))
	if rec.Code != http.StatusMovedPermanently {
		t.Fatalf("got %d, want 301", rec.Code)
	}
	if loc := rec.Header().Get("Location"); loc != "/pages/about/" {
		t.Errorf("Location = %q", loc)
	}
}

func TestUnknownPathsAre404(t *testing.T) {
	h := testHandler(t)
	for _, path := range []string{"/", "/nope/", "/pages/nope", "/pages/about/deeper/"} {
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, path, nil))
		if rec.Code != http.StatusNotFound {
			t.Errorf("GET %s = %d, want 404", path, rec.Code)
		}
	}
}

func multilingualHandler(t *testing.T) http.Handler {
	t.Helper()
	fsys := fstest.MapFS{
		"content/pages/about.md":    {Data: []byte("---\ntitle: About\n---\nEnglish.\n")},
		"content/pages/about.bn.md": {Data: []byte("---\ntitle: পরিচিতি\n---\nবাংলা।\n")},
		"content/pages/now.md":      {Data: []byte("---\ntitle: Now\n---\nOnly English.\n")},
	}
	bundles, err := content.Scan(fsys)
	if err != nil {
		t.Fatal(err)
	}
	r, err := render.New()
	if err != nil {
		t.Fatal(err)
	}
	return Handler(content.NewSite(bundles), r)
}

func TestPrefixedLanguageServesThatVariant(t *testing.T) {
	h := multilingualHandler(t)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/bn/pages/about/", nil))
	if rec.Code != http.StatusOK {
		t.Fatalf("got %d, want 200", rec.Code)
	}
	body := rec.Body.String()
	if !strings.Contains(body, "বাংলা।") || !strings.Contains(body, `lang="bn"`) {
		t.Errorf("did not serve the Bengali variant:\n%s", body)
	}
	if !strings.Contains(body, `rel="canonical" href="/bn/pages/about/"`) {
		t.Error("canonical should name the variant actually served")
	}
	if !strings.Contains(body, `hreflang="en" href="/pages/about/"`) {
		t.Error("hreflang should list the English variant at the root form")
	}
}

func TestMissingVariantFallsBackAndSaysSo(t *testing.T) {
	h := multilingualHandler(t)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/bn/pages/now/", nil))
	if rec.Code != http.StatusOK {
		t.Fatalf("got %d, want 200: the fallback chain must not 404 (ADR-0009)", rec.Code)
	}
	body := rec.Body.String()
	if !strings.Contains(body, "Only English.") {
		t.Error("expected the English body as fallback")
	}
	if !strings.Contains(body, `rel="canonical" href="/pages/now/"`) {
		t.Error("canonical must point at the variant served, not the URL requested")
	}
}

func TestDefaultLanguagePrefixRedirectsToRoot(t *testing.T) {
	h := multilingualHandler(t)
	for path, want := range map[string]string{
		"/en/pages/about/": "/pages/about/",
		"/en/pages/about":  "/pages/about/",
	} {
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, path, nil))
		if rec.Code != http.StatusMovedPermanently {
			t.Errorf("GET %s = %d, want 301: /en/… must never be live (ADR-0009)", path, rec.Code)
			continue
		}
		if loc := rec.Header().Get("Location"); loc != want {
			t.Errorf("GET %s → %q, want %q", path, loc, want)
		}
	}
}

func TestPrefixedSlashlessPathRedirectsWithItsPrefix(t *testing.T) {
	h := multilingualHandler(t)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/bn/pages/about", nil))
	if rec.Code != http.StatusMovedPermanently {
		t.Fatalf("got %d, want 301", rec.Code)
	}
	if loc := rec.Header().Get("Location"); loc != "/bn/pages/about/" {
		t.Errorf("Location = %q, want /bn/pages/about/", loc)
	}
}

func TestUnknownLanguagePrefixIsNotALanguage(t *testing.T) {
	h := multilingualHandler(t)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/fr/pages/about/", nil))
	if rec.Code != http.StatusNotFound {
		t.Errorf("got %d, want 404: fr is not a language this site has", rec.Code)
	}
}

func aliasHandler(t *testing.T) http.Handler {
	t.Helper()
	fsys := fstest.MapFS{
		"content/posts/new-name.md":    {Data: []byte("---\ntitle: New\naliases: [posts/old-name]\n---\nMoved here.\n")},
		"content/posts/new-name.bn.md": {Data: []byte("---\ntitle: নতুন\n---\nএখানে।\n")},
	}
	bundles, err := content.Scan(fsys)
	if err != nil {
		t.Fatal(err)
	}
	r, err := render.New()
	if err != nil {
		t.Fatal(err)
	}
	return Handler(content.NewSite(bundles), r)
}

func TestAliasRedirectsToCanonical(t *testing.T) {
	h := aliasHandler(t)
	for path, want := range map[string]string{
		"/posts/old-name/":    "/posts/new-name/",
		"/bn/posts/old-name/": "/bn/posts/new-name/",
	} {
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, path, nil))
		if rec.Code != http.StatusMovedPermanently {
			t.Errorf("GET %s = %d, want 301", path, rec.Code)
			continue
		}
		if loc := rec.Header().Get("Location"); loc != want {
			t.Errorf("GET %s → %q, want %q", path, loc, want)
		}
	}
}

func TestUnknownPathIsStill404NotAnAliasProbe(t *testing.T) {
	h := aliasHandler(t)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/posts/never-existed/", nil))
	if rec.Code != http.StatusNotFound {
		t.Errorf("got %d, want 404", rec.Code)
	}
}