package timingbench

import (
	"context"
	"math/rand"
	"testing"
	"time"
)

// isPrime checks if a number is a prime number.
func isPrime(n int) bool {
	if n <= 1 {
		return false
	}
	for i := 2; i*i <= n; i++ {
		if n%i == 0 {
			return false
		}
	}
	return true
}

// randomSleep introduces a random delay between 1 and 20 milliseconds.
func randomSleep() {
	time.Sleep(time.Duration(rand.Intn(20)+1) * time.Millisecond)
}

// generatePrimes generates prime numbers up to a given limit.
func generatePrimes(limit int) []int {
	primes := []int{}
	for i := 2; i <= limit; i++ {
		if isPrime(i) {
			primes = append(primes, i)
		}
	}
	return primes
}

// sortRandomSlice generates a slice with random integers and sorts it.
func sortRandomSlice(size int) {
	slice := make([]int, size)
	for i := range slice {
		slice[i] = rand.Intn(10000)
	}
	quickSort(slice)
}

// quickSort sorts a slice of integers using the quicksort algorithm.
func quickSort(arr []int) {
	if len(arr) < 2 {
		return
	}

	left, right := 0, len(arr)-1

	pivotIndex := rand.Int() % len(arr)

	arr[pivotIndex], arr[right] = arr[right], arr[pivotIndex]

	for i := range arr {
		if arr[i] < arr[right] {
			arr[i], arr[left] = arr[left], arr[i]
			left++
		}
	}

	arr[left], arr[right] = arr[right], arr[left]

	quickSort(arr[:left])
	quickSort(arr[left+1:])
}

// multiplyMatrices performs matrix multiplication of two randomly generated matrices.
func multiplyMatrices(size int) {
	matrixA := make([][]int, size)
	matrixB := make([][]int, size)
	result := make([][]int, size)

	for i := 0; i < size; i++ {
		matrixA[i] = make([]int, size)
		matrixB[i] = make([]int, size)
		result[i] = make([]int, size)
		for j := 0; j < size; j++ {
			matrixA[i][j] = rand.Intn(100)
			matrixB[i][j] = rand.Intn(100)
		}
	}

	for i := 0; i < size; i++ {
		for j := 0; j < size; j++ {
			sum := 0
			for k := 0; k < size; k++ {
				sum += matrixA[i][k] * matrixB[k][j]
			}
			result[i][j] = sum
		}
	}
}

// sampleFunction performs a mix of different operations to introduce variability in runtime.
func sampleFunction() error {
	randomSleep()
	generatePrimes(500 + rand.Intn(1500))
	sortRandomSlice(500 + rand.Intn(1500))
	multiplyMatrices(20 + rand.Intn(10))
	return nil
}

func TestTimeFunction(t *testing.T) {
	// Seed the random number generator.
	rand.Seed(time.Now().UnixNano())

	// Define the number of iterations.
	iterations := 1000

	// Create a context with a timeout for cancellation.
	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
	defer cancel()

	// Measure the execution times of the sample function.
	result, err := TimeFunction(ctx, sampleFunction, iterations)
	if err != nil {
		t.Fatalf("Error measuring function: %v", err)
	}

	// Print the timing results.
	t.Logf(result.String())
}