package main

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

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

func TestSchedulesSet(t *testing.T) {
	testCases := []struct {
		name   string
		text   string
		at     *string
		cron   *string
		answer string
		listed string
	}{
		{
			name:   "a one-time schedule at a local time",
			text:   "Remind the user to drink water.",
			at:     new("2026-11-09 09:00"),
			answer: "Schedule 1 set. Next: Monday 2026-11-09 09:00 -03:00.",
			listed: "1 | Monday 2026-11-09 09:00 -03:00 | once | Remind the user to drink water.",
		},
		{
			name:   "a repeating schedule at the next match",
			text:   "Tell the user\nthe time.",
			cron:   new("*/5  * * * *"),
			answer: "Schedule 1 set. Next: Sunday 2026-11-08 20:05 -03:00.",
			listed: "1 | Sunday 2026-11-08 20:05 -03:00 | */5 * * * * | Tell the user the time.",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			schedules, _ := scheduleTestOpen(t)

			answer, err := schedules.Set(tc.text, tc.at, tc.cron)
			require.NoError(t, err)
			require.Equal(t, tc.answer, answer)
			require.Equal(t, tc.listed, schedules.List())
		})
	}
}

func TestSchedulesSetRefuses(t *testing.T) {
	testCases := []struct {
		name    string
		text    string
		at      *string
		cron    *string
		message string
	}{
		{
			name:    "an empty text",
			text:    " \n",
			at:      new("2026-11-09 09:00"),
			message: "the text must have 1 to 4096 bytes",
		},
		{
			name:    "a text that is too long",
			text:    strings.Repeat("x", scheduleTextBytes+1),
			at:      new("2026-11-09 09:00"),
			message: "the text must have 1 to 4096 bytes",
		},
		{
			name:    "neither at nor cron",
			text:    "Tell the user the time.",
			message: "give either at or cron, and null for the other",
		},
		{
			name:    "both at and cron",
			text:    "Tell the user the time.",
			at:      new("2026-11-09 09:00"),
			cron:    new("0 9 * * *"),
			message: "give either at or cron, and null for the other",
		},
		{
			name:    "a time in another layout",
			text:    "Tell the user the time.",
			at:      new("2026-11-09T09:00:00-03:00"),
			message: "at must be a local time such as 2026-11-08 20:00",
		},
		{
			name:    "a time that is past",
			text:    "Tell the user the time.",
			at:      new("2026-11-08 20:00"),
			message: "the time Sunday 2026-11-08 20:00 -03:00 is not after now, Sunday 2026-11-08 20:00 -03:00",
		},
		{
			name:    "runs less than 5 minutes apart",
			text:    "Tell the user the time.",
			cron:    new("* * * * *"),
			message: "at least 5 minutes apart",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			schedules, path := scheduleTestOpen(t)

			_, err := schedules.Set(tc.text, tc.at, tc.cron)
			require.ErrorContains(t, err, tc.message)
			require.NoFileExists(t, path)
		})
	}
}

func TestSchedulesSurviveARestart(t *testing.T) {
	schedules, path := scheduleTestOpen(t)

	_, err := schedules.Set("Remind the user to drink water.", new("2026-11-09 09:00"), nil)
	require.NoError(t, err)

	_, err = schedules.Set("Tell the user the news.", nil, new("0 8 * * 1-5"))
	require.NoError(t, err)

	_, err = schedules.Remove(1)
	require.NoError(t, err)

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

	reopened, err := openSchedules(path, schedules.clock)
	require.NoError(t, err)
	require.Equal(t, "2 | Monday 2026-11-09 08:00 -03:00 | 0 8 * * 1-5 | Tell the user the news.", reopened.List())

	answer, err := reopened.Set("Remind the user to call.", new("2026-11-08 21:00"), nil)
	require.NoError(t, err)
	require.Equal(t, "Schedule 3 set. Next: Sunday 2026-11-08 21:00 -03:00.", answer)
}

func TestSchedulesRemove(t *testing.T) {
	schedules, _ := scheduleTestOpen(t)

	_, err := schedules.Set("Remind the user to drink water.", new("2026-11-09 09:00"), nil)
	require.NoError(t, err)

	answer, err := schedules.Remove(1)
	require.NoError(t, err)
	require.Equal(t, "Schedule 1 removed.", answer)
	require.Equal(t, "No schedules.", schedules.List())

	_, err = schedules.Remove(1)
	require.EqualError(t, err, "no schedule 1")
}

func TestSchedulesDone(t *testing.T) {
	schedules, _ := scheduleTestOpen(t)
	start := schedules.clock()

	_, err := schedules.Set("Remind the user to drink water.", new("2026-11-08 21:00"), nil)
	require.NoError(t, err)

	_, err = schedules.Set("Tell the user the time.", nil, new("0 * * * *"))
	require.NoError(t, err)

	wait, found := schedules.Wait(start)
	require.True(t, found)
	require.Equal(t, time.Hour, wait)

	// The daemon was stopped for three hours, so each schedule missed its
	// times and runs once.
	now := start.Add(3*time.Hour + 30*time.Minute)
	due := schedules.Due(now)
	require.Len(t, due, 2)
	for _, schedule := range due {
		require.NoError(t, schedules.Done(schedule, now))
	}

	require.Empty(t, schedules.Due(now))
	require.Equal(t, "2 | Monday 2026-11-09 00:00 -03:00 | 0 * * * * | Tell the user the time.", schedules.List())

	_, err = schedules.Remove(2)
	require.NoError(t, err)
	require.NoError(t, schedules.Done(due[1], now))
	require.Equal(t, "No schedules.", schedules.List())

	_, found = schedules.Wait(now)
	require.False(t, found)
}

func TestScheduleMessage(t *testing.T) {
	zone := time.FixedZone("", -3*60*60)
	due := time.Date(2026, time.November, 9, 9, 0, 0, 0, zone)
	testCases := []struct {
		name     string
		schedule Schedule
		now      time.Time
		message  string
	}{
		{
			name: "a one-time run on time",
			schedule: Schedule{
				ID:   3,
				Text: "Remind the user to drink water.",
				Due:  due,
			},
			now:     due.Add(time.Second),
			message: "[Schedule 3] Monday 2026-11-09 09:00 -03:00, once\nRemind the user to drink water.\n" + scheduleEmptyReply,
		},
		{
			name: "a late repeating run",
			schedule: Schedule{
				ID:   4,
				Text: "Tell the user the news.",
				Cron: "0 9 * * 1-5",
				Due:  due,
			},
			now:     due.Add(2 * time.Hour),
			message: "[Schedule 4] Monday 2026-11-09 09:00 -03:00, repeats 0 9 * * 1-5\nTell the user the news.\n" + scheduleLateLine + "\n" + scheduleEmptyReply,
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			require.Equal(t, tc.message, tc.schedule.Message(tc.now))
		})
	}
}

func TestOpenSchedulesRefusesABadCron(t *testing.T) {
	path := filepath.Join(t.TempDir(), scheduleFileName)
	require.NoError(t, os.WriteFile(path, []byte(`{"next":1,"schedules":[{"id":1,"text":"x","cron":"* * * * *","due":"2026-11-09T09:00:00-03:00"}]}`), 0o600))

	_, err := openSchedules(path, time.Now)
	require.ErrorContains(t, err, "schedule 1: the runs of")
}

// scheduleTestOpen opens the schedules of a new file, with a clock at Sunday
// 2026-11-08 20:00 -03:00, and returns them and the path of the file.
func scheduleTestOpen(t *testing.T) (*Schedules, string) {
	path := filepath.Join(t.TempDir(), scheduleFileName)
	clock := &TestClock{
		now: time.Date(2026, time.November, 8, 20, 0, 0, 0, time.FixedZone("", -3*60*60)),
	}

	schedules, err := openSchedules(path, clock.Now)
	require.NoError(t, err)

	return schedules, path
}