// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
package str

import (
	"encoding/json"
	"fmt"
	"math/rand"
	"strings"
	"time"
)

const (
	NUMBERSTRING = "0123456789"
	CHARSTRING   = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
)

// get random number string with length.
func GetRandomString(l int) string {
	str := NUMBERSTRING
	bytes := []byte(str)
	result := []byte{}
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	for i := 0; i < l; i++ {
		result = append(result, bytes[r.Intn(len(bytes))])
	}
	return string(result)
}

// get random number+alphabate string with length.
func GetRandomCharString(l int) string {
	str := CHARSTRING
	bytes := []byte(str)
	result := []byte{}
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	for i := 0; i < l; i++ {
		result = append(result, bytes[r.Intn(len(bytes))])
	}
	return string(result)
}

//skip
func Skip(s string, sep string, n int) string {
	seplen := len(sep)
	if seplen == 0 || n < 0 {
		return s
	}

	for {
		i := strings.Index(s, sep)
		if i < 0 {
			return s
		} else {
			s = s[i+seplen:]
			n = n - 1
			if n <= 0 {
				return s
			}
		}
	}
	return s
}

// skip line
func SkipLine(s string, n int) string {
	return Skip(s, "\n", n)
}

// get a map's keys as array.
func MapsKeys(imap interface{}) (keys []string) {
	switch imap.(type) {
	case map[string]string:
		m := imap.(map[string]string)
		for k, _ := range m {
			keys = append(keys, k)
		}
	case map[string]interface{}:
		m := imap.(map[string]interface{})
		for k, _ := range m {
			keys = append(keys, k)
		}
	default:
		panic("Unkown Type")
	}
	return keys
}

// get a map's keys and join it to string.
func MapsKeysString(imap interface{}) string {
	keys := MapsKeys(imap)
	return strings.Join(keys, ",")
}

// string json to string map to string
func JsonstrToStrMap(jsonstr string) (m map[string]string) {
	err := json.Unmarshal([]byte(jsonstr), &m)
	if err != nil {
		panic(fmt.Sprintf("Jsonstr[%s] To MapString failed:%s", jsonstr, err.Error()))
	}
	return m
}

// string to string map to string
//   example: "K1:V1;K2:V2"
//         => {K1:V1, K2:V2}
func StringToStrMap(str string, sep1, sep2 string) (m map[string]string) {
	m = map[string]string{}
	for _, kvstr := range strings.Split(str, sep1) {
		if kv := strings.SplitN(kvstr, sep2, 2); len(kv) == 2 {
			m[kv[0]] = kv[1]
		}
	}
	return m
}