81 lines
1.6 KiB
Go
81 lines
1.6 KiB
Go
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package invited_code
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import (
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"fmt"
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"math"
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"strings"
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)
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type Converter struct {
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Base int
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Length int
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ConvertTable []string
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}
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func (c *Converter) EncodeFromNum(id int64) (string, error) {
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code, err := generateCode(id, c.Base, c.Length, c.ConvertTable)
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if err != nil {
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return "", err
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}
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return code, nil
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}
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func (c *Converter) DecodeFromCode(code string) (int64, error) {
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var result int64 = 0
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length := len(code)
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for i := 0; i < length; i++ {
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char := string(code[i])
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index := -1
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for j, v := range c.ConvertTable {
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if v == char {
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index = j
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break
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}
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}
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if index >= 0 {
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result = result*int64(c.Base) + int64(index)
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} else {
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return 0, fmt.Errorf("character not found in convert table")
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}
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}
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return result, nil
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}
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// generateCode 從 UID 生成 referralCode
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func generateCode(id int64, base int, length int, convertTable []string) (string, error) {
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maxReferralUIDBoundary := int64(math.Pow(float64(len(ConvertTable)), float64(DefaultCodeLen)))
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if id > maxReferralUIDBoundary {
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return "", fmt.Errorf("encode out of range")
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}
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encoded := encodeToBase(id, base, length, convertTable)
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return encoded, nil
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}
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func encodeToBase(num int64, base int, length int, convertTable []string) string {
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result := ""
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for num > 0 {
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index := num % int64(base)
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result = convertTable[index] + result
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num /= int64(base)
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}
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if len(result) < length {
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result = strings.Repeat(convertTable[0], length-len(result)) + result
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}
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return result
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}
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func MustConverter(base int, length int, convertTable []string) ConvertUseCase {
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return &Converter{
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Base: base,
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Length: length,
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ConvertTable: convertTable,
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}
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}
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