package caddyhttp

import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"strings"
	"testing"
)

type responseWriterSpy interface {
	http.ResponseWriter
	Written() string
	CalledReadFrom() bool
}

var (
	_ responseWriterSpy = (*baseRespWriter)(nil)
	_ responseWriterSpy = (*readFromRespWriter)(nil)
)

// a barebones http.ResponseWriter mock
type baseRespWriter []byte

func (brw *baseRespWriter) Write(d []byte) (int, error) {
	*brw = append(*brw, d...)
	return len(d), nil
}
func (brw *baseRespWriter) Header() http.Header        { return nil }
func (brw *baseRespWriter) WriteHeader(statusCode int) {}
func (brw *baseRespWriter) Written() string            { return string(*brw) }
func (brw *baseRespWriter) CalledReadFrom() bool       { return false }

// an http.ResponseWriter mock that supports ReadFrom
type readFromRespWriter struct {
	baseRespWriter
	called bool
}

func (rf *readFromRespWriter) ReadFrom(r io.Reader) (int64, error) {
	rf.called = true
	return io.Copy(&rf.baseRespWriter, r)
}

func (rf *readFromRespWriter) CalledReadFrom() bool { return rf.called }

func TestResponseWriterWrapperReadFrom(t *testing.T) {
	tests := map[string]struct {
		responseWriter responseWriterSpy
		wantReadFrom   bool
	}{
		"no ReadFrom": {
			responseWriter: &baseRespWriter{},
			wantReadFrom:   false,
		},
		"has ReadFrom": {
			responseWriter: &readFromRespWriter{},
			wantReadFrom:   true,
		},
	}
	for name, tt := range tests {
		t.Run(name, func(t *testing.T) {
			// what we expect middlewares to do:
			type myWrapper struct {
				*ResponseWriterWrapper
			}

			wrapped := myWrapper{
				ResponseWriterWrapper: &ResponseWriterWrapper{ResponseWriter: tt.responseWriter},
			}

			const srcData = "boo!"
			// hides everything but Read, since strings.Reader implements WriteTo it would
			// take precedence over our ReadFrom.
			src := struct{ io.Reader }{strings.NewReader(srcData)}

			fmt.Println(name)
			if _, err := io.Copy(wrapped, src); err != nil {
				t.Errorf("Copy() err = %v", err)
			}

			if got := tt.responseWriter.Written(); got != srcData {
				t.Errorf("data = %q, want %q", got, srcData)
			}

			if tt.responseWriter.CalledReadFrom() != tt.wantReadFrom {
				if tt.wantReadFrom {
					t.Errorf("ReadFrom() should have been called")
				} else {
					t.Errorf("ReadFrom() should not have been called")
				}
			}
		})
	}
}

func TestResponseRecorderReadFrom(t *testing.T) {
	tests := map[string]struct {
		responseWriter responseWriterSpy
		shouldBuffer   bool
		wantReadFrom   bool
	}{
		"buffered plain": {
			responseWriter: &baseRespWriter{},
			shouldBuffer:   true,
			wantReadFrom:   false,
		},
		"streamed plain": {
			responseWriter: &baseRespWriter{},
			shouldBuffer:   false,
			wantReadFrom:   false,
		},
		"buffered ReadFrom": {
			responseWriter: &readFromRespWriter{},
			shouldBuffer:   true,
			wantReadFrom:   false,
		},
		"streamed ReadFrom": {
			responseWriter: &readFromRespWriter{},
			shouldBuffer:   false,
			wantReadFrom:   true,
		},
	}
	for name, tt := range tests {
		t.Run(name, func(t *testing.T) {
			var buf bytes.Buffer

			rr := NewResponseRecorder(tt.responseWriter, &buf, func(status int, header http.Header) bool {
				return tt.shouldBuffer
			})

			const srcData = "boo!"
			// hides everything but Read, since strings.Reader implements WriteTo it would
			// take precedence over our ReadFrom.
			src := struct{ io.Reader }{strings.NewReader(srcData)}

			if _, err := io.Copy(rr, src); err != nil {
				t.Errorf("Copy() err = %v", err)
			}

			wantStreamed := srcData
			wantBuffered := ""
			if tt.shouldBuffer {
				wantStreamed = ""
				wantBuffered = srcData
			}

			if got := tt.responseWriter.Written(); got != wantStreamed {
				t.Errorf("streamed data = %q, want %q", got, wantStreamed)
			}
			if got := buf.String(); got != wantBuffered {
				t.Errorf("buffered data = %q, want %q", got, wantBuffered)
			}

			if tt.responseWriter.CalledReadFrom() != tt.wantReadFrom {
				if tt.wantReadFrom {
					t.Errorf("ReadFrom() should have been called")
				} else {
					t.Errorf("ReadFrom() should not have been called")
				}
			}
		})
	}
}
