schema migration and account fixes

very close to rolling this out! just need to address some security concerns first

controller/invite.go

@@ -0,0 +1,67 @@
+package controller
+
+import (
+	"arimelody-web/model"
+	"math/rand"
+	"strings"
+	"time"
+
+	"github.com/jmoiron/sqlx"
+)
+
+var inviteChars = []byte("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
+
+func GetInvite(db *sqlx.DB, code string) (*model.Invite, error) {
+    invite := model.Invite{}
+
+    err := db.Get(&invite, "SELECT * FROM invite WHERE code=$1", code)
+    if err != nil {
+        if strings.Contains(err.Error(), "no rows") {
+            return nil, nil
+        }
+        return nil, err
+    }
+
+    return &invite, nil
+}
+
+func CreateInvite(db *sqlx.DB, length int, lifetime time.Duration) (*model.Invite, error) {
+    invite := model.Invite{
+        CreatedAt: time.Now(),
+        ExpiresAt: time.Now().Add(lifetime),
+    }
+    
+    code := []byte{}
+    for i := 0; i < length; i++ {
+        code = append(code, inviteChars[rand.Intn(len(inviteChars) - 1)])
+    }
+    invite.Code = string(code)
+
+    _, err := db.Exec(
+        "INSERT INTO invite (code, created_at, expires_at) " +
+        "VALUES ($1, $2, $3)",
+        invite.Code,
+        invite.CreatedAt,
+        invite.ExpiresAt,
+    )
+    if err != nil {
+        return nil, err
+    }
+
+    return &invite, nil
+}
+
+func DeleteInvite(db *sqlx.DB, code string) error {
+    _, err := db.Exec("DELETE FROM invite WHERE code=$1", code)
+    return err
+}
+
+func DeleteAllInvites(db *sqlx.DB) error {
+    _, err := db.Exec("DELETE FROM invite")
+    return err
+}
+
+func DeleteExpiredInvites(db *sqlx.DB) error {
+    _, err := db.Exec("DELETE FROM invite WHERE expires_at<current_timestamp")
+    return err
+}