// Copyright 2014 beego Author. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package utils

import (
	"math/rand"
	"time"
)

type reducetype func(interface{}) interface{}
type filtertype func(interface{}) bool

// InSlice checks given string in string slice or not.
func InSlice(v string, sl []string) bool {
	for _, vv := range sl {
		if vv == v {
			return true
		}
	}
	return false
}

// InSliceIface checks given interface in interface slice.
func InSliceIface(v interface{}, sl []interface{}) bool {
	for _, vv := range sl {
		if vv == v {
			return true
		}
	}
	return false
}

// SliceRandList generate an int slice from min to max.
func SliceRandList(min, max int) []int {
	if max < min {
		min, max = max, min
	}
	length := max - min + 1
	t0 := time.Now()
	rand.Seed(int64(t0.Nanosecond()))
	list := rand.Perm(length)
	for index := range list {
		list[index] += min
	}
	return list
}

// SliceMerge merges interface slices to one slice.
func SliceMerge(slice1, slice2 []interface{}) (c []interface{}) {
	c = append(slice1, slice2...)
	return
}

// SliceReduce generates a new slice after parsing every value by reduce function
func SliceReduce(slice []interface{}, a reducetype) (dslice []interface{}) {
	for _, v := range slice {
		dslice = append(dslice, a(v))
	}
	return
}

// SliceRand returns random one from slice.
func SliceRand(a []interface{}) (b interface{}) {
	randnum := rand.Intn(len(a))
	b = a[randnum]
	return
}

// SliceSum sums all values in int64 slice.
func SliceSum(intslice []int64) (sum int64) {
	for _, v := range intslice {
		sum += v
	}
	return
}

// SliceFilter generates a new slice after filter function.
func SliceFilter(slice []interface{}, a filtertype) (ftslice []interface{}) {
	for _, v := range slice {
		if a(v) {
			ftslice = append(ftslice, v)
		}
	}
	return
}

// SliceDiff returns diff slice of slice1 - slice2.
func SliceDiff(slice1, slice2 []interface{}) (diffslice []interface{}) {
	for _, v := range slice1 {
		if !InSliceIface(v, slice2) {
			diffslice = append(diffslice, v)
		}
	}
	return
}

// SliceIntersect returns slice that are present in all the slice1 and slice2.
func SliceIntersect(slice1, slice2 []interface{}) (diffslice []interface{}) {
	for _, v := range slice1 {
		if InSliceIface(v, slice2) {
			diffslice = append(diffslice, v)
		}
	}
	return
}

// SliceChunk separates one slice to some sized slice.
func SliceChunk(slice []interface{}, size int) (chunkslice [][]interface{}) {
	if size >= len(slice) {
		chunkslice = append(chunkslice, slice)
		return
	}
	end := size
	for i := 0; i <= (len(slice) - size); i += size {
		chunkslice = append(chunkslice, slice[i:end])
		end += size
	}
	return
}

// SliceRange generates a new slice from begin to end with step duration of int64 number.
func SliceRange(start, end, step int64) (intslice []int64) {
	for i := start; i <= end; i += step {
		intslice = append(intslice, i)
	}
	return
}

// SlicePad prepends size number of val into slice.
func SlicePad(slice []interface{}, size int, val interface{}) []interface{} {
	if size <= len(slice) {
		return slice
	}
	for i := 0; i < (size - len(slice)); i++ {
		slice = append(slice, val)
	}
	return slice
}

// SliceUnique cleans repeated values in slice.
func SliceUnique(slice []interface{}) (uniqueslice []interface{}) {
	for _, v := range slice {
		if !InSliceIface(v, uniqueslice) {
			uniqueslice = append(uniqueslice, v)
		}
	}
	return
}

// SliceShuffle shuffles a slice.
func SliceShuffle(slice []interface{}) []interface{} {
	for i := 0; i < len(slice); i++ {
		a := rand.Intn(len(slice))
		b := rand.Intn(len(slice))
		slice[a], slice[b] = slice[b], slice[a]
	}
	return slice
}
