feat: member invitation and activation (#535)

Co-authored-by: John Wang <takatost@gmail.com>

api/extensions/ext_mail.py

@@ -0,0 +1,61 @@
+from typing import Optional
+
+import resend
+from flask import Flask
+
+
+class Mail:
+    def __init__(self):
+        self._client = None
+        self._default_send_from = None
+
+    def is_inited(self) -> bool:
+        return self._client is not None
+
+    def init_app(self, app: Flask):
+        if app.config.get('MAIL_TYPE'):
+            if app.config.get('MAIL_DEFAULT_SEND_FROM'):
+                self._default_send_from = app.config.get('MAIL_DEFAULT_SEND_FROM')
+
+            if app.config.get('MAIL_TYPE') == 'resend':
+                api_key = app.config.get('RESEND_API_KEY')
+                if not api_key:
+                    raise ValueError('RESEND_API_KEY is not set')
+
+                resend.api_key = api_key
+                self._client = resend.Emails
+            else:
+                raise ValueError('Unsupported mail type {}'.format(app.config.get('MAIL_TYPE')))
+
+    def send(self, to: str, subject: str, html: str, from_: Optional[str] = None):
+        if not self._client:
+            raise ValueError('Mail client is not initialized')
+
+        if not from_ and self._default_send_from:
+            from_ = self._default_send_from
+
+        if not from_:
+            raise ValueError('mail from is not set')
+
+        if not to:
+            raise ValueError('mail to is not set')
+
+        if not subject:
+            raise ValueError('mail subject is not set')
+
+        if not html:
+            raise ValueError('mail html is not set')
+
+        self._client.send({
+            "from": from_,
+            "to": to,
+            "subject": subject,
+            "html": html
+        })
+
+
+def init_app(app: Flask):
+    mail.init_app(app)
+
+
+mail = Mail()