72 lines
1.6 KiB
Go
72 lines
1.6 KiB
Go
package order
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import (
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"crypto/rand"
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"fmt"
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)
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// OrderId is a 64-bit order identifier with a compact base62 string form, the
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// same scheme the cart uses (cart.CartId) so ids are consistent across the
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// commerce services. The grain is keyed by the raw uint64.
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type OrderId uint64
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const base62Alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
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var base62Rev [256]byte
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func init() {
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for i := range base62Rev {
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base62Rev[i] = 0xFF
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}
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for i := 0; i < len(base62Alphabet); i++ {
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base62Rev[base62Alphabet[i]] = byte(i)
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}
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}
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// String returns the canonical base62 encoding.
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func (id OrderId) String() string { return encodeBase62(uint64(id)) }
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// NewOrderId generates a cryptographically random non-zero id.
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func NewOrderId() (OrderId, error) {
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var b [8]byte
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if _, err := rand.Read(b[:]); err != nil {
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return 0, fmt.Errorf("NewOrderId: %w", err)
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}
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u := uint64(b[0])<<56 | uint64(b[1])<<48 | uint64(b[2])<<40 | uint64(b[3])<<32 |
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uint64(b[4])<<24 | uint64(b[5])<<16 | uint64(b[6])<<8 | uint64(b[7])
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if u == 0 {
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return NewOrderId()
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}
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return OrderId(u), nil
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}
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// ParseOrderId parses a base62 string into an OrderId.
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func ParseOrderId(s string) (OrderId, bool) {
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if len(s) == 0 || len(s) > 11 {
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return 0, false
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}
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var v uint64
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for i := 0; i < len(s); i++ {
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d := base62Rev[s[i]]
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if d == 0xFF {
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return 0, false
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}
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v = v*62 + uint64(d)
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}
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return OrderId(v), true
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}
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func encodeBase62(u uint64) string {
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if u == 0 {
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return "0"
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}
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var buf [11]byte
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i := len(buf)
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for u > 0 {
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i--
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buf[i] = base62Alphabet[u%62]
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u /= 62
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}
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return string(buf[i:])
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}
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