package lo

import (
	"errors"
	"sync"
	"testing"
	"time"

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

func TestAttempt(t *testing.T) {
	t.Parallel()
	is := assert.New(t)

	err := errors.New("failed")

	iter1, err1 := Attempt(42, func(i int) error {
		return nil
	})
	iter2, err2 := Attempt(42, func(i int) error {
		if i == 5 {
			return nil
		}

		return err
	})
	iter3, err3 := Attempt(2, func(i int) error {
		if i == 5 {
			return nil
		}

		return err
	})
	iter4, err4 := Attempt(0, func(i int) error {
		if i < 42 {
			return err
		}

		return nil
	})

	is.Equal(1, iter1)
	is.NoError(err1)
	is.Equal(6, iter2)
	is.NoError(err2)
	is.Equal(2, iter3)
	is.ErrorIs(err3, err)
	is.Equal(43, iter4)
	is.NoError(err4)
}

func TestAttemptWithDelay(t *testing.T) {
	t.Parallel()
	is := assert.New(t)

	err := errors.New("failed")

	iter1, dur1, err1 := AttemptWithDelay(42, 10*time.Millisecond, func(i int, d time.Duration) error {
		return nil
	})
	iter2, dur2, err2 := AttemptWithDelay(42, 10*time.Millisecond, func(i int, d time.Duration) error {
		if i == 5 {
			return nil
		}

		return err
	})
	iter3, dur3, err3 := AttemptWithDelay(2, 10*time.Millisecond, func(i int, d time.Duration) error {
		if i == 5 {
			return nil
		}

		return err
	})
	iter4, dur4, err4 := AttemptWithDelay(0, 10*time.Millisecond, func(i int, d time.Duration) error {
		if i < 10 {
			return err
		}

		return nil
	})

	is.Equal(1, iter1)
	is.GreaterOrEqual(dur1, 0*time.Millisecond)
	is.Less(dur1, 1*time.Millisecond)
	is.NoError(err1)
	is.Equal(6, iter2)
	is.Greater(dur2, 50*time.Millisecond)
	is.Less(dur2, 60*time.Millisecond)
	is.NoError(err2)
	is.Equal(2, iter3)
	is.Greater(dur3, 10*time.Millisecond)
	is.Less(dur3, 20*time.Millisecond)
	is.ErrorIs(err3, err)
	is.Equal(11, iter4)
	is.Greater(dur4, 100*time.Millisecond)
	is.Less(dur4, 115*time.Millisecond)
	is.NoError(err4)
}

func TestAttemptWhile(t *testing.T) {
	t.Parallel()
	is := assert.New(t)

	err := errors.New("failed")

	iter1, err1 := AttemptWhile(42, func(i int) (error, bool) {
		return nil, true
	})

	is.Equal(1, iter1)
	is.NoError(err1)

	iter2, err2 := AttemptWhile(42, func(i int) (error, bool) {
		if i == 5 {
			return nil, true
		}

		return err, true
	})

	is.Equal(6, iter2)
	is.NoError(err2)

	iter3, err3 := AttemptWhile(2, func(i int) (error, bool) {
		if i == 5 {
			return nil, true
		}

		return err, true
	})

	is.Equal(2, iter3)
	is.ErrorIs(err3, err)

	iter4, err4 := AttemptWhile(0, func(i int) (error, bool) {
		if i < 42 {
			return err, true
		}

		return nil, true
	})

	is.Equal(43, iter4)
	is.NoError(err4)

	iter5, err5 := AttemptWhile(0, func(i int) (error, bool) {
		if i == 5 {
			return nil, false
		}

		return err, true
	})

	is.Equal(6, iter5)
	is.NoError(err5)

	iter6, err6 := AttemptWhile(0, func(i int) (error, bool) {
		return nil, false
	})

	is.Equal(1, iter6)
	is.NoError(err6)

	iter7, err7 := AttemptWhile(42, func(i int) (error, bool) {
		if i == 42 {
			return nil, false
		}
		if i < 41 {
			return err, true
		}

		return nil, true
	})

	is.Equal(42, iter7)
	is.NoError(err7)
}

func TestAttemptWhileWithDelay(t *testing.T) {
	t.Parallel()
	is := assert.New(t)

	err := errors.New("failed")

	iter1, dur1, err1 := AttemptWhileWithDelay(42, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
		return nil, true
	})

	is.Equal(1, iter1)
	is.GreaterOrEqual(dur1, 0*time.Millisecond)
	is.Less(dur1, 1*time.Millisecond)
	is.NoError(err1)

	iter2, dur2, err2 := AttemptWhileWithDelay(42, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
		if i == 5 {
			return nil, true
		}

		return err, true
	})

	is.Equal(6, iter2)
	is.Greater(dur2, 50*time.Millisecond)
	is.Less(dur2, 60*time.Millisecond)
	is.NoError(err2)

	iter3, dur3, err3 := AttemptWhileWithDelay(2, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
		if i == 5 {
			return nil, true
		}

		return err, true
	})

	is.Equal(2, iter3)
	is.Greater(dur3, 10*time.Millisecond)
	is.Less(dur3, 20*time.Millisecond)
	is.ErrorIs(err3, err)

	iter4, dur4, err4 := AttemptWhileWithDelay(0, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
		if i < 10 {
			return err, true
		}

		return nil, true
	})

	is.Equal(11, iter4)
	is.Greater(dur4, 100*time.Millisecond)
	is.Less(dur4, 115*time.Millisecond)
	is.NoError(err4)

	iter5, dur5, err5 := AttemptWhileWithDelay(0, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
		if i == 5 {
			return nil, false
		}

		return err, true
	})

	is.Equal(6, iter5)
	is.Greater(dur5, 10*time.Millisecond)
	is.Less(dur5, 115*time.Millisecond)
	is.NoError(err5)

	iter6, dur6, err6 := AttemptWhileWithDelay(0, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
		return nil, false
	})

	is.Equal(1, iter6)
	is.Less(dur6, 10*time.Millisecond)
	is.Less(dur6, 115*time.Millisecond)
	is.NoError(err6)

	iter7, dur7, err7 := AttemptWhileWithDelay(42, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
		if i == 42 {
			return nil, false
		}
		if i < 41 {
			return err, true
		}

		return nil, true
	})

	is.Equal(42, iter7)
	is.Less(dur7, 500*time.Millisecond)
	is.NoError(err7)
}

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

	f1 := func() {
		println("1. Called once after 10ms when func stopped invoking!")
	}
	f2 := func() {
		println("2. Called once after 10ms when func stopped invoking!")
	}
	f3 := func() {
		println("3. Called once after 10ms when func stopped invoking!")
	}

	d1, _ := NewDebounce(10*time.Millisecond, f1)

	// execute 3 times
	for i := 0; i < 3; i++ {
		for j := 0; j < 10; j++ {
			d1()
		}
		time.Sleep(20 * time.Millisecond)
	}

	d2, _ := NewDebounce(10*time.Millisecond, f2)

	// execute once because it is always invoked and only last invoke is worked after 100ms
	for i := 0; i < 3; i++ {
		for j := 0; j < 5; j++ {
			d2()
		}
		time.Sleep(5 * time.Millisecond)
	}

	time.Sleep(10 * time.Millisecond)

	// execute once because it is canceled after 200ms.
	d3, cancel := NewDebounce(10*time.Millisecond, f3)
	for i := 0; i < 3; i++ {
		for j := 0; j < 10; j++ {
			d3()
		}
		time.Sleep(20 * time.Millisecond)
		if i == 0 {
			cancel()
		}
	}
}

func TestDebounceBy(t *testing.T) {
	t.Parallel()
	is := assert.New(t)

	mu := sync.Mutex{}
	output := map[int]int{0: 0, 1: 0, 2: 0}

	f1 := func(key, count int) {
		mu.Lock()
		output[key] += count
		mu.Unlock()
		// fmt.Printf("[key=%d] 1. Called once after 10ms when func stopped invoking!\n", key)
	}
	f2 := func(key, count int) {
		mu.Lock()
		output[key] += count
		mu.Unlock()
		// fmt.Printf("[key=%d] 2. Called once after 10ms when func stopped invoking!\n", key)
	}
	f3 := func(key, count int) {
		mu.Lock()
		output[key] += count
		mu.Unlock()
		// fmt.Printf("[key=%d] 3. Called once after 10ms when func stopped invoking!\n", key)
	}

	d1, _ := NewDebounceBy(10*time.Millisecond, f1)

	// execute 3 times
	for i := 0; i < 3; i++ {
		for j := 0; j < 10; j++ {
			for k := 0; k < 3; k++ {
				d1(k)
			}
		}
		time.Sleep(20 * time.Millisecond)
	}

	mu.Lock()
	is.Equal(30, output[0])
	is.Equal(30, output[1])
	is.Equal(30, output[2])
	mu.Unlock()

	d2, _ := NewDebounceBy(10*time.Millisecond, f2)

	// execute once because it is always invoked and only last invoke is worked after 100ms
	for i := 0; i < 3; i++ {
		for j := 0; j < 5; j++ {
			for k := 0; k < 3; k++ {
				d2(k)
			}
		}
		time.Sleep(5 * time.Millisecond)
	}

	time.Sleep(10 * time.Millisecond)

	mu.Lock()
	is.Equal(45, output[0])
	is.Equal(45, output[1])
	is.Equal(45, output[2])
	mu.Unlock()

	// execute once because it is canceled after 200ms.
	d3, cancel := NewDebounceBy(10*time.Millisecond, f3)
	for i := 0; i < 3; i++ {
		for j := 0; j < 10; j++ {
			for k := 0; k < 3; k++ {
				d3(k)
			}
		}

		time.Sleep(20 * time.Millisecond)
		if i == 0 {
			for k := 0; k < 3; k++ {
				cancel(k)
			}
		}
	}

	mu.Lock()
	is.Equal(75, output[0])
	is.Equal(75, output[1])
	is.Equal(75, output[2])
	mu.Unlock()
}

func TestTransaction(t *testing.T) {
	t.Parallel()
	is := assert.New(t)

	// no error
	{
		transaction := NewTransaction[int]().
			Then(
				func(state int) (int, error) {
					return state + 100, nil
				},
				func(state int) int {
					return state - 100
				},
			).
			Then(
				func(state int) (int, error) {
					return state + 21, nil
				},
				func(state int) int {
					return state - 21
				},
			)

		state, err := transaction.Process(21)
		is.Equal(142, state)
		is.NoError(err)
	}

	// with error
	{
		transaction := NewTransaction[int]().
			Then(
				func(state int) (int, error) {
					return state + 100, nil
				},
				func(state int) int {
					return state - 100
				},
			).
			Then(
				func(state int) (int, error) {
					return state, assert.AnError
				},
				func(state int) int {
					return state - 21
				},
			).
			Then(
				func(state int) (int, error) {
					return state + 42, nil
				},
				func(state int) int {
					return state - 42
				},
			)

		state, err := transaction.Process(21)
		is.Equal(21, state)
		is.ErrorIs(err, assert.AnError)
	}

	// with error + update value
	{
		transaction := NewTransaction[int]().
			Then(
				func(state int) (int, error) {
					return state + 100, nil
				},
				func(state int) int {
					return state - 100
				},
			).
			Then(
				func(state int) (int, error) {
					return state + 21, assert.AnError
				},
				func(state int) int {
					return state - 21
				},
			).
			Then(
				func(state int) (int, error) {
					return state + 42, nil
				},
				func(state int) int {
					return state - 42
				},
			)

		state, err := transaction.Process(21)
		is.Equal(42, state)
		is.ErrorIs(err, assert.AnError)
	}
}

func TestNewThrottle(t *testing.T) {
	t.Parallel()
	is := assert.New(t)
	callCount := 0
	f1 := func() {
		callCount++
	}
	th, reset := NewThrottle(10*time.Millisecond, f1)

	is.Zero(callCount)
	for j := 0; j < 100; j++ {
		th()
	}
	is.Equal(1, callCount)

	time.Sleep(15 * time.Millisecond)

	for j := 0; j < 100; j++ {
		th()
	}

	is.Equal(2, callCount)

	// reset counter
	reset()
	th()
	is.Equal(3, callCount)
}

func TestNewThrottleWithCount(t *testing.T) {
	t.Parallel()
	is := assert.New(t)
	callCount := 0
	f1 := func() {
		callCount++
	}
	th, reset := NewThrottleWithCount(10*time.Millisecond, 3, f1)

	// the function does not throttle for initial count number
	for i := 0; i < 20; i++ {
		th()
	}
	is.Equal(3, callCount)

	time.Sleep(15 * time.Millisecond)

	for i := 0; i < 20; i++ {
		th()
	}

	is.Equal(6, callCount)

	reset()
	for i := 0; i < 20; i++ {
		th()
	}

	is.Equal(9, callCount)
}

func TestNewThrottleBy(t *testing.T) {
	t.Parallel()
	is := assert.New(t)
	callCountA := 0
	callCountB := 0
	f1 := func(key string) {
		if key == "a" {
			callCountA++
		} else {
			callCountB++
		}
	}
	th, reset := NewThrottleBy(10*time.Millisecond, f1)

	is.Zero(callCountA)
	is.Zero(callCountB)
	for j := 0; j < 100; j++ {
		th("a")
		th("b")
	}
	is.Equal(1, callCountA)
	is.Equal(1, callCountB)

	time.Sleep(15 * time.Millisecond)

	for j := 0; j < 100; j++ {
		th("a")
		th("b")
	}

	is.Equal(2, callCountA)
	is.Equal(2, callCountB)

	// reset counter
	reset()
	th("a")
	is.Equal(3, callCountA)
	is.Equal(2, callCountB)
}

func TestNewThrottleByWithCount(t *testing.T) {
	t.Parallel()
	is := assert.New(t)

	callCountA := 0
	callCountB := 0
	f1 := func(key string) {
		if key == "a" {
			callCountA++
		} else {
			callCountB++
		}
	}
	th, reset := NewThrottleByWithCount(10*time.Millisecond, 3, f1)

	// the function does not throttle for initial count number
	for i := 0; i < 20; i++ {
		th("a")
		th("b")
	}
	is.Equal(3, callCountA)
	is.Equal(3, callCountB)

	time.Sleep(15 * time.Millisecond)

	for i := 0; i < 20; i++ {
		th("a")
		th("b")
	}

	is.Equal(6, callCountA)
	is.Equal(6, callCountB)

	reset()
	for i := 0; i < 20; i++ {
		th("a")
	}

	is.Equal(9, callCountA)
	is.Equal(6, callCountB)
}