chore: initial commit of ai site platform

Co-authored-by: Cursor <cursoragent@cursor.com>

platform/internal/userstore/creds.go

@@ -0,0 +1,102 @@
+package userstore
+
+import (
+	"context"
+	"crypto/rand"
+	"fmt"
+	"strings"
+)
+
+const passwordAlphabet = "ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz23456789"
+const usernameAlphabet = "abcdefghijkmnopqrstuvwxyz23456789"
+const usernameFirst = "abcdefghijkmnopqrstuvwxyz"
+
+// RandomPassword 生成可读随机密码（不含易混字符 0/O/1/l）。
+func RandomPassword(n int) (string, error) {
+	if n < 8 {
+		n = 12
+	}
+	b := make([]byte, n)
+	if _, err := rand.Read(b); err != nil {
+		return "", err
+	}
+	out := make([]byte, n)
+	for i := range b {
+		out[i] = passwordAlphabet[int(b[i])%len(passwordAlphabet)]
+	}
+	return string(out), nil
+}
+
+// RandomUsername 生成随机登录名（字母开头，仅小写字母与数字，默认 10 位）。
+func RandomUsername() (string, error) {
+	const n = 10
+	b := make([]byte, n)
+	if _, err := rand.Read(b); err != nil {
+		return "", err
+	}
+	out := make([]byte, n)
+	out[0] = usernameFirst[int(b[0])%len(usernameFirst)]
+	for i := 1; i < n; i++ {
+		out[i] = usernameAlphabet[int(b[i])%len(usernameAlphabet)]
+	}
+	return string(out), nil
+}
+
+// AllocUniqueUsername 分配全局唯一随机用户名。
+func AllocUniqueUsername(ctx context.Context, exists func(context.Context, string) (bool, error)) (string, error) {
+	var last error
+	for i := 0; i < 16; i++ {
+		u, err := RandomUsername()
+		if err != nil {
+			return "", err
+		}
+		ok, err := exists(ctx, u)
+		if err != nil {
+			return "", err
+		}
+		if ok {
+			last = fmt.Errorf("username collision")
+			continue
+		}
+		return u, nil
+	}
+	if last != nil {
+		return "", fmt.Errorf("无法生成唯一用户名: %v", last)
+	}
+	return "", fmt.Errorf("无法生成唯一用户名")
+}
+
+// Deprecated: 保留测试兼容；新逻辑请用 RandomUsername / AllocUniqueUsername。
+func SuggestAdminUsername(slug string) string {
+	s := strings.ToLower(strings.TrimSpace(slug))
+	var b strings.Builder
+	for _, r := range s {
+		if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') {
+			b.WriteRune(r)
+		}
+	}
+	base := b.String()
+	if base == "" {
+		base = "co"
+	}
+	if len(base) > 20 {
+		base = base[:20]
+	}
+	return base + "_adm"
+}
+
+// Deprecated: 见 AllocUniqueUsername。
+func NextUsernameCandidate(base string, attempt int) string {
+	base = strings.TrimSpace(base)
+	if base == "" {
+		base = "user"
+	}
+	if attempt <= 0 {
+		return base
+	}
+	suffix, err := RandomPassword(4)
+	if err != nil {
+		return fmt.Sprintf("%s%d", base, attempt)
+	}
+	return fmt.Sprintf("%s_%s", base, strings.ToLower(suffix))
+}