package main

import (
	"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)
	}
}