package main

import (
	"errors"
	"testing"

	"github.com/stretchr/testify/require"
)

func TestQueuedAppendResumesWithoutADuplicate(t *testing.T) {
	dir := t.TempDir()
	memory, err := openMemory(t.Context(), dir, newTestClock().Now, newFakeSummarizer(), discardLog())
	require.NoError(t, err)

	var saved *int

	first, err := memory.AppendOnce("user", "Record the gate size.", nil, func(id int) error {
		saved = &id

		require.Equal(t, 0, memory.log.Len())

		return nil
	})
	require.NoError(t, err)
	require.NoError(t, memory.Close())

	memory, err = openMemory(t.Context(), dir, newTestClock().Now, newFakeSummarizer(), discardLog())
	require.NoError(t, err)

	defer func() {
		require.NoError(t, memory.Close())
	}()

	second, err := memory.AppendOnce("user", first.Text, saved, func(int) error {
		t.Fatal("a recorded message must not be prepared again")

		return nil
	})
	require.NoError(t, err)
	require.Equal(t, first, second)
	require.Equal(t, 1, memory.Len())
}

func TestQueuedAppendRetriesAnUnwrittenPreparedMessage(t *testing.T) {
	memory, err := openMemory(t.Context(), t.TempDir(), newTestClock().Now, newFakeSummarizer(), discardLog())
	require.NoError(t, err)

	defer func() {
		require.NoError(t, memory.Close())
	}()

	failure := errors.New("fake queue write failure")

	var saved *int

	_, err = memory.AppendOnce("work", "[Garden] Check the gate.", nil, func(id int) error {
		saved = &id

		return failure
	})
	require.ErrorIs(t, err, failure)
	require.Equal(t, 0, memory.Len())

	message, err := memory.AppendOnce("work", "[Garden] Check the gate.", saved, func(id int) error {
		require.Equal(t, *saved, id)

		return nil
	})
	require.NoError(t, err)
	require.Equal(t, 0, message.ID)
	require.Equal(t, 1, memory.Len())
}

func TestQueuedAppendRefusesAnInvalidReceipt(t *testing.T) {
	memory, err := openMemory(t.Context(), t.TempDir(), newTestClock().Now, newFakeSummarizer(), discardLog())
	require.NoError(t, err)

	defer func() {
		require.NoError(t, memory.Close())
	}()

	_, err = memory.Append("user", "Keep the original.")
	require.NoError(t, err)

	testCases := []struct {
		name  string
		id    int
		cause string
	}{
		{
			name:  "receipt points to different text",
			id:    0,
			cause: "does not match",
		},
		{
			name:  "receipt skips a log position",
			id:    2,
			cause: "beyond the log",
		},
		{
			name:  "receipt has a negative position",
			id:    -1,
			cause: "read queued message",
		},
	}
	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			_, err := memory.AppendOnce("user", "Other text.", &tc.id, func(int) error {
				t.Fatal("an invalid receipt must not be prepared")

				return nil
			})
			require.ErrorContains(t, err, tc.cause)
			require.Equal(t, 1, memory.Len())
		})
	}
}