package main

import (
	"errors"
	"path/filepath"
	"testing"
	"time"
)

type clock struct{ now time.Time }

func (c *clock) Now() time.Time { return c.now }

func testLimiter(t *testing.T, cfg Config, at string) (*Limiter, *clock) {
	t.Helper()
	moment, err := time.Parse(time.RFC3339, at)
	if err != nil {
		t.Fatal(err)
	}
	cfg.Timezone = "UTC"
	c := &clock{now: moment}
	limiter, err := NewLimiter(cfg, "", c.Now)
	if err != nil {
		t.Fatal(err)
	}
	return limiter, c
}

func TestInWindowTable(t *testing.T) {
	at := func(text string) time.Time {
		moment, _ := time.Parse("15:04", text)
		return moment
	}
	cases := []struct {
		from, to, now string
		want          bool
	}{
		{"", "", "12:00", true},
		{"09:00", "17:00", "09:00", true},
		{"09:00", "17:00", "16:59", true},
		{"09:00", "17:00", "17:00", false},
		{"09:00", "17:00", "08:59", false},
		{"22:00", "06:00", "23:30", true},
		{"22:00", "06:00", "05:59", true},
		{"22:00", "06:00", "06:00", false},
		{"22:00", "06:00", "12:00", false},
		{"10:00", "10:00", "03:00", true},
	}
	for _, item := range cases {
		if got := InWindow(item.from, item.to, at(item.now)); got != item.want {
			t.Errorf("%s-%s at %s: got %v", item.from, item.to, item.now, got)
		}
	}
}

func TestAcquireConcurrencyCapAndServerCannotWiden(t *testing.T) {
	cfg := DefaultConfig()
	cfg.MaxConcurrent = 2
	limiter, _ := testLimiter(t, cfg, "2026-10-15T12:00:00Z")
	limiter.ApplyServer(&ServerLimits{MaxConcurrentPerNode: 8}, &ServerSettings{MaxConcurrent: 8})
	if limiter.Acquire() != "" || limiter.Acquire() != "" {
		t.Fatal("two slots should be free")
	}
	if got := limiter.Acquire(); got != RefuseConcurrency {
		t.Fatalf("third acquire: %q", got)
	}
	limiter.Release()
	if got := limiter.Acquire(); got != "" {
		t.Fatalf("after release: %q", got)
	}
}

func TestServerCanNarrowConcurrency(t *testing.T) {
	cfg := DefaultConfig()
	cfg.MaxConcurrent = 4
	limiter, _ := testLimiter(t, cfg, "2026-10-15T12:00:00Z")
	limiter.ApplyServer(&ServerLimits{MaxConcurrentPerNode: 2}, &ServerSettings{MaxConcurrent: 1})
	if limiter.Acquire() != "" {
		t.Fatal("first slot")
	}
	if got := limiter.Acquire(); got != RefuseConcurrency {
		t.Fatalf("got %q", got)
	}
}

func TestBandwidthCapLocalAndDayRollover(t *testing.T) {
	cfg := DefaultConfig()
	cfg.BandwidthMBDay = 1
	limiter, c := testLimiter(t, cfg, "2026-10-15T23:00:00Z")
	limiter.ApplyServer(&ServerLimits{MaxDonorMBPerDay: 20480}, &ServerSettings{BandwidthMBDay: 9999})
	if limiter.Acquire() != "" {
		t.Fatal("fresh day must allow")
	}
	limiter.Release()
	limiter.AddBytes(mebibyte - 10)
	if got := limiter.Remaining(); got != 10 {
		t.Fatalf("remaining %d", got)
	}
	limiter.AddBytes(10)
	if got := limiter.Acquire(); got != RefuseBandwidth {
		t.Fatalf("got %q", got)
	}
	c.now = c.now.Add(2 * time.Hour)
	if got := limiter.Acquire(); got != "" {
		t.Fatalf("next day: %q", got)
	}
}

func TestServerCanNarrowBandwidth(t *testing.T) {
	cfg := DefaultConfig()
	cfg.BandwidthMBDay = 500
	limiter, _ := testLimiter(t, cfg, "2026-10-15T12:00:00Z")
	limiter.ApplyServer(nil, &ServerSettings{BandwidthMBDay: 2})
	if got := limiter.Remaining(); got != 2*mebibyte {
		t.Fatalf("remaining %d", got)
	}
}

func TestActiveHoursLocalAndServer(t *testing.T) {
	cfg := DefaultConfig()
	cfg.ActiveFrom, cfg.ActiveTo = "22:00", "06:00"
	limiter, c := testLimiter(t, cfg, "2026-10-15T12:00:00Z")
	if got := limiter.Acquire(); got != RefuseHours {
		t.Fatalf("noon: %q", got)
	}
	c.now = c.now.Add(11 * time.Hour)
	if got := limiter.Acquire(); got != "" {
		t.Fatalf("23:00: %q", got)
	}
	limiter.Release()
	limiter.ApplyServer(nil, &ServerSettings{ActiveFrom: "01:00", ActiveTo: "02:00", Timezone: "UTC"})
	if got := limiter.Acquire(); got != RefuseHours {
		t.Fatalf("server window: %q", got)
	}
}

func TestUsagePersistsAcrossRestart(t *testing.T) {
	path := filepath.Join(t.TempDir(), "usage.json")
	cfg := DefaultConfig()
	cfg.Timezone = "UTC"
	moment := time.Date(2026, 10, 15, 12, 0, 0, 0, time.UTC)
	c := &clock{now: moment}
	first, err := NewLimiter(cfg, path, c.Now)
	if err != nil {
		t.Fatal(err)
	}
	first.AddBytes(12345)
	first.Flush()
	second, err := NewLimiter(cfg, path, c.Now)
	if err != nil {
		t.Fatal(err)
	}
	if _, used, _ := second.Usage(); used != 12345 {
		t.Fatalf("used %d", used)
	}
	c.now = moment.Add(24 * time.Hour)
	if _, used, _ := second.Usage(); used != 0 {
		t.Fatalf("next day used %d", used)
	}
	if got := ReadUsage(path, time.UTC, moment); got != 12345 {
		t.Fatalf("read usage %d", got)
	}
}

func TestAcquireRefusesOnBatteryOnlyWhenAsked(t *testing.T) {
	limiter, c := testLimiter(t, DefaultConfig(), "2026-01-15T12:00:00Z")
	calls := 0
	onBattery := true
	limiter.SetBatteryProbe(func() (bool, error) { calls++; return onBattery, nil }, nil)
	if got := limiter.Acquire(); got != "" {
		t.Fatalf("setting off must ignore the probe: %q", got)
	}
	limiter.Release()
	if calls != 0 {
		t.Fatalf("probe ran %d times with the setting off", calls)
	}
	limiter.ApplyServer(nil, &ServerSettings{PauseOnBattery: true})
	if got := limiter.Acquire(); got != RefuseBattery {
		t.Fatalf("got %q", got)
	}
	onBattery = false
	if got := limiter.Acquire(); got != RefuseBattery || calls != 1 {
		t.Fatalf("cached result expected: %q calls %d", got, calls)
	}
	c.now = c.now.Add(16 * time.Second)
	if got := limiter.Acquire(); got != "" || calls != 2 {
		t.Fatalf("after cache expiry: %q calls %d", got, calls)
	}
}

func TestBatteryProbeErrorMeansMainsAndLogsOnce(t *testing.T) {
	limiter, c := testLimiter(t, DefaultConfig(), "2026-01-15T12:00:00Z")
	logged := 0
	limiter.SetBatteryProbe(func() (bool, error) { return true, errors.New("no sysfs") }, func(string, ...any) { logged++ })
	limiter.ApplyServer(nil, &ServerSettings{PauseOnBattery: true})
	for i := 0; i < 3; i++ {
		if got := limiter.Acquire(); got != "" {
			t.Fatalf("probe error must not refuse: %q", got)
		}
		limiter.Release()
		c.now = c.now.Add(20 * time.Second)
	}
	if logged != 1 {
		t.Fatalf("logged %d times", logged)
	}
}

func TestBatteryHelpers(t *testing.T) {
	if !parsePmset("Now drawing from 'Battery Power'\n -InternalBattery-0") || parsePmset("Now drawing from 'AC Power'") {
		t.Fatal("pmset parse")
	}
	cases := []struct {
		ac, flag byte
		want     bool
	}{{0, 1, true}, {0, 8, true}, {1, 1, false}, {0, 128, false}, {255, 255, false}, {0, 255, false}}
	for _, item := range cases {
		if got := windowsOnBattery(item.ac, item.flag); got != item.want {
			t.Errorf("ac %d flag %d: %v", item.ac, item.flag, got)
		}
	}
}

const (
	parityBase    = 1767225600
	parityStep    = 40009
	paritySamples = 200
)

var parityCases = []struct{ from, to, zone, bits string }{
	{"09:00", "17:00", "Europe/Amsterdam", "01010000001010101010000101010101000000101010100000010101010000001010101010000101010101000000101010100000010101010000001010101010000101010101000000101010100000010101010000001010101010000001010101010000"},
	{"22:00", "06:00", "America/New_York", "00010101010000001010101000000101010101000010101010100000010101010000001010101000000101010101000010101010100000010101010000001010101000000101010101000000101010101000010101010100000010101010000001010101"},
	{"08:30", "12:15", "Asia/Kolkata", "00000001010000000000101000000000010101000000000010100000000001010000000000101000000000000101000000000010100000000001010000000000101000000000000101000000000010100000000001010000000000101010000000000101"},
	{"00:00", "12:00", "Pacific/Auckland", "01101010101010110101010101010010101010101001010101010101101010101010110101010101010010101010101001010101010101101010101010110101010101010010101010101011010101010101101010101010100101010101010010101010"},
	{"10:00", "10:00", "UTC", "11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111"},
	{"09:00", "17:00", "Not/AZone", "01010000101010101000000101010100000010101010000001010101010000001010101000000101010100000010101010100001010101010000001010101000000101010100000010101010100001010101010000001010101000000101010100000010"},
	{"23:00", "01:00", "Australia/Lord_Howe", "00000000000010000000000001010000000000001000000000000100000000000010000000000001010000000000001000000000000100000000000010000000000000010000000000001000000000000100000000000010000000000000010000000000"},
	{"", "", "Europe/Amsterdam", "11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111"},
}

func TestInWindowParityWithPythonScheduler(t *testing.T) {
	for _, item := range parityCases {
		zone, err := time.LoadLocation(item.zone)
		if err != nil {
			zone = time.UTC
		}
		for index := 0; index < paritySamples; index++ {
			moment := time.Unix(int64(parityBase+index*parityStep), 0).In(zone)
			if got := InWindow(item.from, item.to, moment); got != (item.bits[index] == '1') {
				t.Fatalf("%s-%s %s #%d: got %v", item.from, item.to, item.zone, index, got)
			}
		}
	}
}