package handlers

import (
	"context"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/go-chi/chi/v5"

	"sneak.berlin/go/pixa/internal/encurl"
	"sneak.berlin/go/pixa/internal/imgcache"
)

// newEncTestServer builds a router serving the encrypted-URL route with a
// generator seeded by the shared test signing key. The image service is left
// nil: these tests exercise validation that rejects a token before any image
// is fetched, so the handler must never reach the service.
func newEncTestServer(t *testing.T) (*encurl.Generator, http.Handler) {
	t.Helper()

	encGen, err := encurl.NewGenerator(testSigningKey)
	if err != nil {
		t.Fatalf("encurl.NewGenerator() error = %v", err)
	}

	h := &Handlers{
		log:    slog.New(slog.DiscardHandler),
		encGen: encGen,
	}

	r := chi.NewRouter()
	r.Get("/v1/e/{token}/*", h.HandleImageEnc())

	return encGen, r
}

// getEncToken issues a GET for the given token and returns the recorder.
func getEncToken(srv http.Handler, token string) *httptest.ResponseRecorder {
	req := httptest.NewRequestWithContext(
		context.Background(), http.MethodGet, "/v1/e/"+token+"/img.jpg", nil)
	rec := httptest.NewRecorder()
	srv.ServeHTTP(rec, req)

	return rec
}

// TestHandleImageEnc_OverLimitDimension_Returns400 verifies that a decrypted
// token requesting a dimension beyond MaxDimension is rejected with 400
// instead of reaching the image processor and libvips.
func TestHandleImageEnc_OverLimitDimension_Returns400(t *testing.T) {
	t.Parallel()

	encGen, srv := newEncTestServer(t)

	token, err := encGen.Generate(&encurl.Payload{
		SourceHost: "cdn.example.com",
		SourcePath: "/photo.jpg",
		Width:      100000,
		Height:     100000,
	})
	if err != nil {
		t.Fatalf("Generate() error = %v", err)
	}

	rec := getEncToken(srv, token)

	if rec.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusBadRequest)
	}
}

// TestHandleImageEnc_InvalidFitMode_Returns400 verifies that a decrypted token
// carrying an unrecognized fit mode is rejected with 400 rather than surfacing
// as a 500 from the image processor's default branch.
func TestHandleImageEnc_InvalidFitMode_Returns400(t *testing.T) {
	t.Parallel()

	encGen, srv := newEncTestServer(t)

	token, err := encGen.Generate(&encurl.Payload{
		SourceHost: "cdn.example.com",
		SourcePath: "/photo.jpg",
		Width:      800,
		Height:     600,
		FitMode:    imgcache.FitMode("bogus"),
	})
	if err != nil {
		t.Fatalf("Generate() error = %v", err)
	}

	rec := getEncToken(srv, token)

	if rec.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusBadRequest)
	}
}

// TestHandleImageEnc_IfNoneMatch_Returns304 verifies that an image served
// through an encrypted URL carries an ETag, and that a request whose
// If-None-Match is that ETag is answered 304 Not Modified with no body.
func TestHandleImageEnc_IfNoneMatch_Returns304(t *testing.T) {
	t.Parallel()

	h, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
	target := encPhotoURL(t, h)

	rec := httptest.NewRecorder()
	srv.ServeHTTP(rec, httptest.NewRequestWithContext(
		t.Context(), http.MethodGet, target, nil))

	etag := rec.Header().Get("ETag")
	t.Logf("GET: %d, ETag %q", rec.Code, etag)

	if rec.Code != http.StatusOK || etag == "" {
		t.Fatalf("GET: status = %d, ETag = %q, want %d and an ETag",
			rec.Code, etag, http.StatusOK)
	}

	req := httptest.NewRequestWithContext(t.Context(), http.MethodGet, target, nil)
	req.Header.Set("If-None-Match", etag)

	rec = httptest.NewRecorder()
	srv.ServeHTTP(rec, req)
	t.Logf("GET with If-None-Match: %d, %d body bytes", rec.Code, rec.Body.Len())

	if rec.Code != http.StatusNotModified || rec.Body.Len() != 0 {
		t.Errorf("status = %d with %d body bytes, want %d with none",
			rec.Code, rec.Body.Len(), http.StatusNotModified)
	}
}

// TestHandleImageEnc_HEAD_ReturnsHeadersOnly verifies that HEAD on an
// encrypted URL is answered 200 with the headers GET sends and no body.
func TestHandleImageEnc_HEAD_ReturnsHeadersOnly(t *testing.T) {
	t.Parallel()

	h, _ := newSignedHostServer(t, slog.New(slog.DiscardHandler))

	r := chi.NewRouter()
	r.Head("/v1/e/{token}/*", h.HandleImageEnc())

	rec := httptest.NewRecorder()
	r.ServeHTTP(rec, httptest.NewRequestWithContext(
		t.Context(), http.MethodHead, encPhotoURL(t, h), nil))
	t.Logf("HEAD: %d, headers %v, %d body bytes",
		rec.Code, rec.Header(), rec.Body.Len())

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusOK)
	}

	for _, name := range []string{
		"Content-Type", "Content-Length", "Cache-Control", "ETag",
	} {
		if rec.Header().Get(name) == "" {
			t.Errorf("HEAD response has no %s", name)
		}
	}

	if rec.Body.Len() != 0 {
		t.Errorf("HEAD response body has %d bytes, want none", rec.Body.Len())
	}
}