package slice

import (
	"github.com/fthvgb1/wp-go/helper"
	"github.com/fthvgb1/wp-go/helper/number"
)

func Map[T, R any](arr []T, fn func(T) R) []R {
	r := make([]R, 0, len(arr))
	for _, t := range arr {
		r = append(r, fn(t))
	}
	return r
}

func FilterAndMap[N any, T any](arr []T, fn func(T) (N, bool)) (r []N) {
	for _, t := range arr {
		x, ok := fn(t)
		if ok {
			r = append(r, x)
		}
	}
	return
}

func Walk[T any](arr []T, fn func(*T)) {
	for i := 0; i < len(arr); i++ {
		fn(&arr[i])
	}
}

func First[T any](arr []T, fn func(T) bool) (int, T) {
	for i, t := range arr {
		if fn(t) {
			return i, t
		}
	}
	var r T
	return -1, r
}

func Last[T any](arr []T, fn func(T) bool) (int, T) {
	for i := len(arr) - 1; i > 0; i-- {
		if fn(arr[i]) {
			return i, arr[i]
		}
	}
	var r T
	return -1, r
}

func Filter[T any](arr []T, fn func(T) bool) []T {
	var r []T
	for _, t := range arr {
		if fn(t) {
			r = append(r, t)
		}
	}
	return r
}

func Reduce[R, T any](arr []T, fn func(T, R) R, r R) R {
	for _, t := range arr {
		r = fn(t, r)
	}
	return r
}

func Reverse[T any](arr []T) []T {
	var r = make([]T, 0, len(arr))
	for i := len(arr); i > 0; i-- {
		r = append(r, arr[i-1])
	}
	return r
}

func ReverseSelf[T any](arr []T) []T {
	l := len(arr)
	half := l / 2
	for i := 0; i < half; i++ {
		arr[i], arr[l-i-1] = arr[l-i-1], arr[i]
	}
	return arr
}

func SimpleToMap[K comparable, V any](arr []V, fn func(V) K) map[K]V {
	return ToMap(arr, func(v V) (K, V) {
		return fn(v), v
	}, true)
}

func ToMap[K comparable, V, T any](arr []V, fn func(V) (K, T), isCoverPrev bool) map[K]T {
	m := make(map[K]T)
	for _, v := range arr {
		k, r := fn(v)
		if !isCoverPrev {
			if _, ok := m[k]; ok {
				continue
			}
		}
		m[k] = r
	}
	return m
}

func Pagination[T any](arr []T, page, pageSize int) []T {
	start := (page - 1) * pageSize
	l := len(arr)
	if start > l {
		start = l
	}
	end := page * pageSize
	if l < end {
		end = l
	}
	return arr[start:end]
}

func Chunk[T any](arr []T, size int) [][]T {
	var r [][]T
	i := 0
	for {
		if len(arr) <= size+i {
			r = append(r, arr[i:])
			break
		}
		r = append(r, arr[i:i+size])
		i += size
	}
	return r
}

func Slice[T any](arr []T, offset, length int) (r []T) {
	l := len(arr)
	if length == 0 {
		length = l - offset
	}
	if l > offset && l >= offset+length {
		r = append(make([]T, 0, length), arr[offset:offset+length]...)
		arr = append(arr[:offset], arr[offset+length:]...)
	} else if l <= offset {
		return
	} else if l > offset && l < offset+length {
		r = append(make([]T, 0, length), arr[offset:]...)
		arr = arr[:offset]
	}
	return
}

func FilterAndToMap[K comparable, V, T any](arr []T, fn func(T) (K, V, bool)) map[K]V {
	r := make(map[K]V)
	for _, t := range arr {
		k, v, ok := fn(t)
		if ok {
			r[k] = v
		}
	}
	return r
}

func Comb[T any](arr []T, m int) (r [][]T) {
	if m == 1 {
		for _, t := range arr {
			r = append(r, []T{t})
		}
		return
	}
	l := len(arr) - m
	for i := 0; i <= l; i++ {
		next := Slice(arr, i+1, 0)
		nexRes := Comb(next, m-1)
		for _, re := range nexRes {
			t := append([]T{arr[i]}, re...)
			r = append(r, t)
		}
	}
	return r
}

func GroupBy[K comparable, T, V any](a []T, fn func(T) (K, V)) map[K][]V {
	r := make(map[K][]V)
	for _, t := range a {
		k, v := fn(t)
		if _, ok := r[k]; !ok {
			r[k] = []V{v}
		} else {
			r[k] = append(r[k], v)
		}
	}
	return r
}

func ToAnySlice[T any](a []T) []any {
	return Map(a, helper.ToAny[T])
}

func Fill[T any](start, len int, v T) []T {
	r := make([]T, start+len)
	for i := 0; i < len; i++ {
		r[start+i] = v
	}
	return r
}

// Pad returns a copy of the array padded to size specified by length with value. If length is positive then the array is padded on the right, if it's negative then on the left. If the absolute value of length is less than or equal to the length of the array then no padding takes place.
func Pad[T any](a []T, length int, v T) []T {
	l := len(a)
	if length > l {
		return append(a, Fill(0, length-l, v)...)
	} else if length < 0 && -length > l-1 {
		return append(Fill(0, -length-2, v), a...)
	}
	return a
}

func Pop[T any](a *[]T) T {
	arr := *a
	v := arr[len(arr)-1]

	*a = append(arr[:len(arr)-1])
	return v
}

func Rand[T any](a []T) (int, T) {
	i := number.Rand(0, len(a)-1)
	return i, a[i]
}

func RandPop[T any](a *[]T) (T, int) {
	arr := *a
	if len(arr) == 0 {
		var r T
		return r, 0
	}
	i := number.Rand(0, len(arr)-1)
	v := arr[i]
	if len(arr)-1 == i {
		*a = append(arr[:i])
	} else {
		*a = append(arr[:i], arr[i+1:]...)
	}
	return v, len(arr) - 1
}

func Shift[T any](a *[]T) (T, int) {
	arr := *a
	l := len(arr)
	if l > 0 {
		v := arr[0]
		*a = arr[1:]
		return v, l - 1
	}
	var r T
	return r, 0
}