package command

import (
	"bytes"
	"errors"
	"io"
	"strings"
	"testing"

	gomock "github.com/golang/mock/gomock"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func linesToReadCloser(lines []string) io.ReadCloser {
	s := strings.Join(lines, "\n")
	return io.NopCloser(bytes.NewBufferString(s))
}

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

	errDummy := errors.New("dummy")

	testCases := map[string]struct {
		stdout        []string
		stdoutPipeErr error
		stderr        []string
		stderrPipeErr error
		startErr      error
		waitErr       error
		err           error
	}{
		"no output": {},
		"success": {
			stdout: []string{"hello", "world"},
			stderr: []string{"some", "error"},
		},
		"stdout pipe error": {
			stdoutPipeErr: errDummy,
			err:           errDummy,
		},
		"stderr pipe error": {
			stderrPipeErr: errDummy,
			err:           errDummy,
		},
		"start error": {
			startErr: errDummy,
			err:      errDummy,
		},
		"wait error": {
			waitErr: errDummy,
		},
	}

	for name, testCase := range testCases {
		testCase := testCase
		t.Run(name, func(t *testing.T) {
			t.Parallel()

			ctrl := gomock.NewController(t)

			stdout := linesToReadCloser(testCase.stdout)
			stderr := linesToReadCloser(testCase.stderr)

			mockCmd := NewMockexecCmd(ctrl)

			mockCmd.EXPECT().StdoutPipe().
				Return(stdout, testCase.stdoutPipeErr)
			if testCase.stdoutPipeErr == nil {
				mockCmd.EXPECT().StderrPipe().Return(stderr, testCase.stderrPipeErr)
				if testCase.stderrPipeErr == nil {
					mockCmd.EXPECT().Start().Return(testCase.startErr)
					if testCase.startErr == nil {
						mockCmd.EXPECT().Wait().Return(testCase.waitErr)
					}
				}
			}

			stdoutLines, stderrLines, waitError, err := start(mockCmd)

			if testCase.err != nil {
				require.Error(t, err)
				assert.Equal(t, testCase.err.Error(), err.Error())
				assert.Nil(t, stdoutLines)
				assert.Nil(t, stderrLines)
				assert.Nil(t, waitError)
				return
			}

			require.NoError(t, err)

			var stdoutIndex, stderrIndex int

			done := false
			for !done {
				select {
				case line := <-stdoutLines:
					assert.Equal(t, testCase.stdout[stdoutIndex], line)
					stdoutIndex++
				case line := <-stderrLines:
					assert.Equal(t, testCase.stderr[stderrIndex], line)
					stderrIndex++
				case err := <-waitError:
					if testCase.waitErr != nil {
						require.Error(t, err)
						assert.Equal(t, testCase.waitErr.Error(), err.Error())
					} else {
						assert.NoError(t, err)
					}
					done = true
				}
			}

			assert.Equal(t, len(testCase.stdout), stdoutIndex)
			assert.Equal(t, len(testCase.stderr), stderrIndex)
		})
	}
}