package main

import (
	"fmt"
	"os"
	"path/filepath"
	"testing"
	"time"

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

func TestWhatsAppBatchesFollowTheTimesOfTheMessages(t *testing.T) {
	testCases := []struct {
		name  string
		times []time.Duration
		sizes []int
	}{
		{
			name:  "messages close together form one batch",
			times: []time.Duration{0, 10 * time.Second, 30 * time.Second},
			sizes: []int{3},
		},
		{
			name:  "a quiet chat starts a new batch",
			times: []time.Duration{0, 10 * time.Second, 31 * time.Second},
			sizes: []int{2, 1},
		},
		{
			name:  "a batch ends after two minutes",
			times: []time.Duration{0, 20 * time.Second, 40 * time.Second, 60 * time.Second, 80 * time.Second, 100 * time.Second, 120 * time.Second, 140 * time.Second},
			sizes: []int{7, 1},
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			batches := whatsappTestState(t, filepath.Join(t.TempDir(), whatsappStateFileName))
			start := time.Date(2026, 1, 1, 12, 0, 0, 0, time.UTC)
			for index, offset := range tc.times {
				_, err := batches.Add(whatsappTestChat, WhatsAppMessage{
					ID:   string(rune('a' + index)),
					Time: start.Add(offset),
					Text: "hi",
				}, time.Now())
				require.NoError(t, err)
			}

			require.NoError(t, batches.CloseAll())

			var sizes []int

			for _, batch := range batches.Closed() {
				sizes = append(sizes, len(batch.Messages))
			}

			require.Equal(t, tc.sizes, sizes)
		})
	}
}

func TestWhatsAppBatchClosesAtFiftyMessages(t *testing.T) {
	batches := whatsappTestState(t, filepath.Join(t.TempDir(), whatsappStateFileName))
	start := time.Date(2026, 1, 1, 12, 0, 0, 0, time.UTC)
	for index := range whatsappBatchMessages {
		closed, err := batches.Add(whatsappTestChat, WhatsAppMessage{
			ID:   time.Duration(index).String(),
			Time: start,
			Text: "hi",
		}, time.Now())
		require.NoError(t, err)
		require.Equal(t, index == whatsappBatchMessages-1, closed)
	}

	require.Len(t, batches.Closed(), 1)
}

func TestWhatsAppBatchClosesInRealTime(t *testing.T) {
	batches := whatsappTestState(t, filepath.Join(t.TempDir(), whatsappStateFileName))
	arrival := time.Date(2026, 1, 1, 12, 0, 0, 0, time.UTC)
	for index, offset := range []time.Duration{0, 15 * time.Second, 30 * time.Second} {
		_, err := batches.Add(whatsappTestChat, WhatsAppMessage{
			ID:   string(rune('a' + index)),
			Time: arrival,
			Text: "hi",
		}, arrival.Add(offset))
		require.NoError(t, err)
	}

	wait, open := batches.Wait(arrival.Add(40 * time.Second))
	require.True(t, open)
	require.Equal(t, 10*time.Second, wait)

	closed, err := batches.CloseDue(arrival.Add(49 * time.Second))
	require.NoError(t, err)
	require.False(t, closed)

	closed, err = batches.CloseDue(arrival.Add(50 * time.Second))
	require.NoError(t, err)
	require.True(t, closed)

	_, open = batches.Wait(arrival.Add(50 * time.Second))
	require.False(t, open)
}

func TestWhatsAppBatchesSurviveARestart(t *testing.T) {
	path := filepath.Join(t.TempDir(), whatsappDirName, whatsappStateFileName)
	batches := whatsappTestState(t, path)
	for _, id := range []string{"a", "a", "b"} {
		_, err := batches.Add(whatsappTestChat, WhatsAppMessage{
			ID:   id,
			Time: time.Date(2026, 1, 1, 12, 0, 0, 0, time.UTC),
			Text: "hi " + id,
		}, time.Now())
		require.NoError(t, err)
	}

	info, err := os.Stat(path)
	require.NoError(t, err)
	require.Equal(t, os.FileMode(0o600), info.Mode().Perm())

	again := whatsappTestState(t, path)
	require.NoError(t, again.CloseAll())

	closed := again.Closed()
	require.Len(t, closed, 1)
	require.Equal(t, []string{"hi a", "hi b"}, []string{closed[0].Messages[0].Text, closed[0].Messages[1].Text})

	require.NoError(t, again.Remove(closed[0].Number))
	require.Empty(t, whatsappTestState(t, path).Closed())
}

func TestWhatsAppStateRefusesABrokenFile(t *testing.T) {
	path := filepath.Join(t.TempDir(), whatsappStateFileName)
	require.NoError(t, os.WriteFile(path, []byte("{"), 0o600))

	_, err := openWhatsAppState(path)
	require.ErrorContains(t, err, path)
}

func TestWhatsAppStateKeepsTheLastSendRecords(t *testing.T) {
	state := whatsappTestState(t, filepath.Join(t.TempDir(), whatsappStateFileName))
	for index := range whatsappSendRecords + 1 {
		require.NoError(t, state.PutSend(WhatsAppSend{
			ID:    fmt.Sprint(index),
			State: whatsappSent,
		}))
	}

	_, found := state.Send("0")
	require.False(t, found)

	_, found = state.Send(fmt.Sprint(whatsappSendRecords))
	require.True(t, found)
}

// whatsappTestState opens the batches of the state file at path with the
// times of the plan.
func whatsappTestState(t *testing.T, path string) *WhatsAppState {
	t.Helper()

	batches, err := openWhatsAppState(path)
	require.NoError(t, err)

	return batches
}