package server

import (
	"bytes"
	"encoding/json"
	"image/jpeg"
	"net/http"
	"net/http/httptest"
	"testing"

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

// TestImageProxyRefusesComputedSideAboveMaximum requests sizes of a 3000x600
// and a 600x3000 PNG through both image routes. A size with one side 0, whose
// side computed from the source's proportions would be above 8192, is refused
// with 400 and the JSON error body. The sizes after those refusals are served
// as before, which also shows that a refusal is not cached as a failed fetch of
// the source: orig, a size with both sides given, and a size with one side 0
// whose computed side stays within 8192.
func TestImageProxyRefusesComputedSideAboveMaximum(t *testing.T) {
	t.Parallel()

	wide := encodeTestPNG(t, 3000, 600)
	tall := encodeTestPNG(t, 600, 3000)

	upstream := httptest.NewServer(http.HandlerFunc(
		func(w http.ResponseWriter, r *http.Request) {
			w.Header().Set("Content-Type", "image/png")

			if r.URL.Path == "/tall.png" {
				_, _ = w.Write(tall)

				return
			}

			_, _ = w.Write(wide)
		}))
	t.Cleanup(upstream.Close)

	s, _, _ := startImageProxy(t, upstream)

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

	tests := []struct {
		path string
		// size is the size of the /v1/image/ URL, and width and height are
		// those of the encrypted URL
		size          string
		width, height int
		// wantWidth and wantHeight are the served image's, 0 for a refusal
		wantWidth, wantHeight int
	}{
		{"/wide.png", "0x8192", 0, 8192, 0, 0},
		{"/tall.png", "8192x0", 8192, 0, 0, 0},
		{"/wide.png", "orig", 0, 0, 3000, 600},
		{"/wide.png", "300x200", 300, 200, 300, 200},
		{"/wide.png", "0x300", 0, 300, 1500, 300},
		{"/tall.png", "300x0", 300, 0, 300, 1500},
	}

	for _, tt := range tests {
		token, err := generator.Generate(&encurl.Payload{
			SourceHost: upstreamHost, SourcePath: tt.path,
			Width: tt.width, Height: tt.height, Format: imgcache.FormatJPEG,
		})
		if err != nil {
			t.Fatalf("encurl Generate: %v", err)
		}

		for _, target := range []string{
			"/v1/image/" + upstreamHost + tt.path + "/" + tt.size + ".jpeg",
			"/v1/e/" + token + "/img.jpg",
		} {
			rec := httptest.NewRecorder()
			s.ServeHTTP(rec, httptest.NewRequestWithContext(
				t.Context(), http.MethodGet, target, nil))
			t.Logf("GET %s: %d, Content-Type %s",
				target, rec.Code, rec.Header().Get("Content-Type"))

			if tt.wantWidth == 0 {
				checkSizeRefused(t, rec)
			} else {
				checkServedSize(t, rec, tt.wantWidth, tt.wantHeight)
			}
		}
	}
}

// checkSizeRefused checks that rec answers 400 with the JSON error body that
// refuses a size whose side computed from the source's proportions is above
// 8192.
func checkSizeRefused(t *testing.T, rec *httptest.ResponseRecorder) {
	t.Helper()

	const wantError = "size too large for the source: " +
		"the side computed from its proportions is above 8192"

	var body struct {
		Error  string `json:"error"`
		Status int    `json:"status"`
	}

	err := json.Unmarshal(rec.Body.Bytes(), &body)
	if err != nil {
		t.Errorf("status %d, body is not JSON: %v", rec.Code, err)

		return
	}

	if rec.Code != http.StatusBadRequest || body.Status != http.StatusBadRequest ||
		body.Error != wantError {
		t.Errorf("status %d, body %+v, want %d and the error %q",
			rec.Code, body, http.StatusBadRequest, wantError)
	}
}

// checkServedSize checks that rec answers 200 with a JPEG of wantWidth by
// wantHeight.
func checkServedSize(
	t *testing.T, rec *httptest.ResponseRecorder, wantWidth, wantHeight int,
) {
	t.Helper()

	if rec.Code != http.StatusOK {
		t.Errorf("status %d, want %d; body %s",
			rec.Code, http.StatusOK, rec.Body.String())

		return
	}

	served, err := jpeg.DecodeConfig(bytes.NewReader(rec.Body.Bytes()))
	if err != nil {
		t.Errorf("decoding the served JPEG: %v", err)

		return
	}

	if served.Width != wantWidth || served.Height != wantHeight {
		t.Errorf("served %dx%d, want %dx%d",
			served.Width, served.Height, wantWidth, wantHeight)
	}
}