package tracing_test

import (
	"bufio"
	"crypto/rand"
	"net"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
	"golang.org/x/xerrors"

	"github.com/coder/coder/v2/coderd/tracing"
)

func TestStatusWriter(t *testing.T) {
	t.Parallel()

	t.Run("WriteHeader", func(t *testing.T) {
		t.Parallel()

		var (
			rec = httptest.NewRecorder()
			w   = &tracing.StatusWriter{ResponseWriter: rec}
		)

		w.WriteHeader(http.StatusOK)
		require.Equal(t, http.StatusOK, w.Status)
		// Validate that the code is written to the underlying Response.
		require.Equal(t, http.StatusOK, rec.Code)
	})

	t.Run("WriteHeaderTwice", func(t *testing.T) {
		t.Parallel()

		var (
			rec  = httptest.NewRecorder()
			w    = &tracing.StatusWriter{ResponseWriter: rec}
			code = http.StatusNotFound
		)

		w.WriteHeader(code)
		w.WriteHeader(http.StatusOK)
		// Validate that we only record the first status code.
		require.Equal(t, code, w.Status)
		// Validate that the code is written to the underlying Response.
		require.Equal(t, code, rec.Code)
	})

	t.Run("WriteNoHeader", func(t *testing.T) {
		t.Parallel()
		var (
			rec  = httptest.NewRecorder()
			w    = &tracing.StatusWriter{ResponseWriter: rec}
			body = []byte("hello")
		)

		_, err := w.Write(body)
		require.NoError(t, err)

		// Should set the status to OK.
		require.Equal(t, http.StatusOK, w.Status)
		// We don't record the body for codes <400.
		require.Equal(t, []byte(nil), w.ResponseBody())
		require.Equal(t, body, rec.Body.Bytes())
	})

	t.Run("WriteAfterHeader", func(t *testing.T) {
		t.Parallel()
		var (
			rec  = httptest.NewRecorder()
			w    = &tracing.StatusWriter{ResponseWriter: rec}
			body = []byte("hello")
			code = http.StatusInternalServerError
		)

		w.WriteHeader(code)
		_, err := w.Write(body)
		require.NoError(t, err)

		require.Equal(t, code, w.Status)
		require.Equal(t, body, w.ResponseBody())
		require.Equal(t, body, rec.Body.Bytes())
	})

	t.Run("WriteMaxBody", func(t *testing.T) {
		t.Parallel()
		var (
			rec = httptest.NewRecorder()
			w   = &tracing.StatusWriter{ResponseWriter: rec}
			// 8kb body.
			body = make([]byte, 8<<10)
			code = http.StatusInternalServerError
		)

		_, err := rand.Read(body)
		require.NoError(t, err)

		w.WriteHeader(code)
		_, err = w.Write(body)
		require.NoError(t, err)

		require.Equal(t, code, w.Status)
		require.Equal(t, body, rec.Body.Bytes())
		require.Equal(t, body[:4096], w.ResponseBody())
	})

	t.Run("Hijack", func(t *testing.T) {
		t.Parallel()
		rec := httptest.NewRecorder()

		w := &tracing.StatusWriter{ResponseWriter: hijacker{rec}}

		_, _, err := w.Hijack()
		require.Error(t, err)
		require.Equal(t, "hijacked", err.Error())
	})

	t.Run("Unwrap", func(t *testing.T) {
		t.Parallel()
		rec := httptest.NewRecorder()
		w := &tracing.StatusWriter{ResponseWriter: rec}

		got := w.Unwrap()
		require.Equal(t, rec, got, "Unwrap should return the inner ResponseWriter")
	})

	t.Run("SetWriteDeadlineThroughMiddleware", func(t *testing.T) {
		t.Parallel()

		// Use a real HTTP server so the ResponseWriter is backed by
		// a net.Conn that supports SetWriteDeadline.
		// http.ResponseController reaches it by calling Unwrap() on
		// each wrapper in the chain.
		var setDeadlineErr error
		handlerCalled := false
		handler := tracing.StatusWriterMiddleware(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			handlerCalled = true
			rc := http.NewResponseController(w)
			setDeadlineErr = rc.SetWriteDeadline(time.Now().Add(time.Minute))
			w.WriteHeader(http.StatusNoContent)
		}))

		srv := httptest.NewServer(handler)
		t.Cleanup(srv.Close)

		req, err := http.NewRequestWithContext(t.Context(), http.MethodGet, srv.URL, nil)
		require.NoError(t, err)
		resp, err := http.DefaultClient.Do(req)
		require.NoError(t, err)
		resp.Body.Close()
		require.True(t, handlerCalled, "handler must be invoked")
		require.Equal(t, http.StatusNoContent, resp.StatusCode)
		// Assert in the test goroutine, not the handler goroutine.
		require.NoError(t, setDeadlineErr, "SetWriteDeadline should succeed through StatusWriter")
	})

	t.Run("Middleware", func(t *testing.T) {
		t.Parallel()

		var (
			sw *tracing.StatusWriter
			rr = httptest.NewRecorder()
		)
		tracing.StatusWriterMiddleware(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			sw = w.(*tracing.StatusWriter)
			w.WriteHeader(http.StatusNoContent)
		})).ServeHTTP(rr, httptest.NewRequest("GET", "/", nil))

		require.Equal(t, http.StatusNoContent, rr.Code, "rr status code not set")
		require.Equal(t, http.StatusNoContent, sw.Status, "sw status code not set")
	})
}

type hijacker struct {
	http.ResponseWriter
}

func (hijacker) Hijack() (net.Conn, *bufio.ReadWriter, error) {
	return nil, nil, xerrors.New("hijacked")
}

func (h hijacker) Flush() {
	if f, ok := h.ResponseWriter.(http.Flusher); ok {
		f.Flush()
	}
}