package lo

import (
	"context"
	"sync"
	"testing"
	"time"

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

func TestSynchronize(t *testing.T) {
	t.Parallel()
	testWithTimeout(t, 100*time.Millisecond)
	is := assert.New(t)

	// check that callbacks are not executed concurrently
	{
		start := time.Now()

		wg := sync.WaitGroup{}
		wg.Add(10)

		s := Synchronize()

		for i := 0; i < 10; i++ {
			go s.Do(func() {
				time.Sleep(5 * time.Millisecond)
				wg.Done()
			})
		}

		wg.Wait()

		duration := time.Since(start)

		is.Greater(duration, 50*time.Millisecond)
		is.Less(duration, 60*time.Millisecond)
	}

	// check locker is locked
	{
		mu := &sync.Mutex{}
		s := Synchronize(mu)

		s.Do(func() {
			is.False(mu.TryLock())
		})
		is.True(mu.TryLock())

		Try0(func() {
			mu.Unlock()
		})
	}

	// check we don't accept multiple arguments
	{
		is.PanicsWithValue("unexpected arguments", func() {
			mu := &sync.Mutex{}
			Synchronize(mu, mu, mu)
		})
	}
}

func TestAsync(t *testing.T) {
	t.Parallel()
	testWithTimeout(t, 100*time.Millisecond)
	is := assert.New(t)

	sync := make(chan struct{})

	ch := Async(func() int {
		<-sync
		return 10
	})

	sync <- struct{}{}

	select {
	case result := <-ch:
		is.Equal(result, 10)
	case <-time.After(time.Millisecond):
		is.Fail("Async should not block")
	}
}

func TestAsyncX(t *testing.T) {
	t.Parallel()
	testWithTimeout(t, 100*time.Millisecond)
	is := assert.New(t)

	{
		sync := make(chan struct{})

		ch := Async0(func() {
			<-sync
		})

		sync <- struct{}{}

		select {
		case <-ch:
		case <-time.After(time.Millisecond):
			is.Fail("Async0 should not block")
		}
	}

	{
		sync := make(chan struct{})

		ch := Async1(func() int {
			<-sync
			return 10
		})

		sync <- struct{}{}

		select {
		case result := <-ch:
			is.Equal(result, 10)
		case <-time.After(time.Millisecond):
			is.Fail("Async1 should not block")
		}
	}

	{
		sync := make(chan struct{})

		ch := Async2(func() (int, string) {
			<-sync
			return 10, "Hello"
		})

		sync <- struct{}{}

		select {
		case result := <-ch:
			is.Equal(result, Tuple2[int, string]{10, "Hello"})
		case <-time.After(time.Millisecond):
			is.Fail("Async2 should not block")
		}
	}

	{
		sync := make(chan struct{})

		ch := Async3(func() (int, string, bool) {
			<-sync
			return 10, "Hello", true
		})

		sync <- struct{}{}

		select {
		case result := <-ch:
			is.Equal(result, Tuple3[int, string, bool]{10, "Hello", true})
		case <-time.After(time.Millisecond):
			is.Fail("Async3 should not block")
		}
	}

	{
		sync := make(chan struct{})

		ch := Async4(func() (int, string, bool, float64) {
			<-sync
			return 10, "Hello", true, 3.14
		})

		sync <- struct{}{}

		select {
		case result := <-ch:
			is.Equal(result, Tuple4[int, string, bool, float64]{10, "Hello", true, 3.14})
		case <-time.After(time.Millisecond):
			is.Fail("Async4 should not block")
		}
	}

	{
		sync := make(chan struct{})

		ch := Async5(func() (int, string, bool, float64, string) {
			<-sync
			return 10, "Hello", true, 3.14, "World"
		})

		sync <- struct{}{}

		select {
		case result := <-ch:
			is.Equal(result, Tuple5[int, string, bool, float64, string]{10, "Hello", true, 3.14, "World"})
		case <-time.After(time.Millisecond):
			is.Fail("Async5 should not block")
		}
	}

	{
		sync := make(chan struct{})

		ch := Async6(func() (int, string, bool, float64, string, int) {
			<-sync
			return 10, "Hello", true, 3.14, "World", 100
		})

		sync <- struct{}{}

		select {
		case result := <-ch:
			is.Equal(result, Tuple6[int, string, bool, float64, string, int]{10, "Hello", true, 3.14, "World", 100})
		case <-time.After(time.Millisecond):
			is.Fail("Async6 should not block")
		}
	}
}

func TestWaitFor(t *testing.T) {
	t.Parallel()

	testTimeout := 100 * time.Millisecond
	longTimeout := 2 * testTimeout
	shortTimeout := 4 * time.Millisecond

	t.Run("exist condition works", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		laterTrue := func(i int) bool {
			return i >= 5
		}

		iter, duration, ok := WaitFor(laterTrue, longTimeout, time.Millisecond)
		is.Equal(6, iter, "unexpected iteration count")
		is.InEpsilon(6*time.Millisecond, duration, float64(500*time.Microsecond))
		is.True(ok)
	})

	t.Run("counter is incremented", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		counter := 0
		alwaysFalse := func(i int) bool {
			is.Equal(counter, i)
			counter++
			return false
		}

		iter, duration, ok := WaitFor(alwaysFalse, shortTimeout, 1050*time.Microsecond)
		is.Equal(counter, iter, "unexpected iteration count")
		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
		is.False(ok)
	})

	alwaysTrue := func(_ int) bool { return true }
	alwaysFalse := func(_ int) bool { return false }

	t.Run("short timeout works", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		iter, duration, ok := WaitFor(alwaysFalse, shortTimeout, 10*time.Millisecond)
		is.Equal(0, iter, "unexpected iteration count")
		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
		is.False(ok)
	})

	t.Run("timeout works", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		shortTimeout := 4 * time.Millisecond
		iter, duration, ok := WaitFor(alwaysFalse, shortTimeout, 10*time.Millisecond)
		is.Equal(0, iter, "unexpected iteration count")
		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
		is.False(ok)
	})

	t.Run("exist on first condition", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		iter, duration, ok := WaitFor(alwaysTrue, 10*time.Millisecond, time.Millisecond)
		is.Equal(1, iter, "unexpected iteration count")
		is.InEpsilon(time.Millisecond, duration, float64(5*time.Microsecond))
		is.True(ok)
	})
}

func TestWaitForWithContext(t *testing.T) {
	t.Parallel()

	testTimeout := 100 * time.Millisecond
	longTimeout := 2 * testTimeout
	shortTimeout := 4 * time.Millisecond

	t.Run("exist condition works", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		laterTrue := func(_ context.Context, i int) bool {
			return i >= 5
		}

		iter, duration, ok := WaitForWithContext(context.Background(), laterTrue, longTimeout, time.Millisecond)
		is.Equal(6, iter, "unexpected iteration count")
		is.InEpsilon(6*time.Millisecond, duration, float64(500*time.Microsecond))
		is.True(ok)
	})

	t.Run("counter is incremented", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		counter := 0
		alwaysFalse := func(_ context.Context, i int) bool {
			is.Equal(counter, i)
			counter++
			return false
		}

		iter, duration, ok := WaitForWithContext(context.Background(), alwaysFalse, shortTimeout, 1050*time.Microsecond)
		is.Equal(counter, iter, "unexpected iteration count")
		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
		is.False(ok)
	})

	alwaysTrue := func(_ context.Context, _ int) bool { return true }
	alwaysFalse := func(_ context.Context, _ int) bool { return false }

	t.Run("short timeout works", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		iter, duration, ok := WaitForWithContext(context.Background(), alwaysFalse, shortTimeout, 10*time.Millisecond)
		is.Equal(0, iter, "unexpected iteration count")
		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
		is.False(ok)
	})

	t.Run("timeout works", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		shortTimeout := 4 * time.Millisecond
		iter, duration, ok := WaitForWithContext(context.Background(), alwaysFalse, shortTimeout, 10*time.Millisecond)
		is.Equal(0, iter, "unexpected iteration count")
		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
		is.False(ok)
	})

	t.Run("exist on first condition", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		iter, duration, ok := WaitForWithContext(context.Background(), alwaysTrue, 10*time.Millisecond, time.Millisecond)
		is.Equal(1, iter, "unexpected iteration count")
		is.InEpsilon(time.Millisecond, duration, float64(5*time.Microsecond))
		is.True(ok)
	})

	t.Run("context cancellation stops everything", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		expiringCtx, clean := context.WithTimeout(context.Background(), 8*time.Millisecond)
		t.Cleanup(func() {
			clean()
		})

		iter, duration, ok := WaitForWithContext(expiringCtx, alwaysFalse, 100*time.Millisecond, 3*time.Millisecond)
		is.Equal(2, iter, "unexpected iteration count")
		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
		is.False(ok)
	})

	t.Run("canceled context stops everything", func(t *testing.T) {
		t.Parallel()

		testWithTimeout(t, testTimeout)
		is := assert.New(t)

		canceledCtx, cancel := context.WithCancel(context.Background())
		cancel()

		iter, duration, ok := WaitForWithContext(canceledCtx, alwaysFalse, 100*time.Millisecond, 1050*time.Microsecond)
		is.Equal(0, iter, "unexpected iteration count")
		is.InEpsilon(1*time.Millisecond, duration, float64(5*time.Microsecond))
		is.False(ok)
	})
}