From b26ce25719f9478cbc02cd0f0ec7e63c50ec62d3 Mon Sep 17 00:00:00 2001
From: grillazz <the@grillazz.com>
Date: Fri, 20 Dec 2024 18:06:21 +0100
Subject: [PATCH 1/3] add singleton meta with no args

---
 app/utils/singleton.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/app/utils/singleton.py b/app/utils/singleton.py
index 0c94176..85df17e 100644
--- a/app/utils/singleton.py
+++ b/app/utils/singleton.py
@@ -16,3 +16,21 @@ def __call__(cls, *args, **kwargs):
                 instance = super().__call__(*args, **kwargs)
                 cls._instances[cls] = instance
         return cls._instances[cls]
+
+
+class SingletonMetaNoArgs(type):
+    """
+    Singleton metaclass for classes without parameters on constructor,
+    for compatibility with FastApi Depends() function.
+    """
+
+    _instances = {}
+
+    _lock: Lock = Lock()
+
+    def __call__(cls):
+        with cls._lock:
+            if cls not in cls._instances:
+                instance = super().__call__()
+                cls._instances[cls] = instance
+        return cls._instances[cls]
\ No newline at end of file

From 4a0944fec6d3d71cb60d3b5cfa1cba3ac332f829 Mon Sep 17 00:00:00 2001
From: grillazz <the@grillazz.com>
Date: Fri, 20 Dec 2024 18:06:29 +0100
Subject: [PATCH 2/3] smtp config

---
 app/config.py | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/app/config.py b/app/config.py
index 9ad9a56..5c617d3 100644
--- a/app/config.py
+++ b/app/config.py
@@ -1,10 +1,17 @@
 import os
 
-from pydantic import PostgresDsn, RedisDsn, computed_field
+from pydantic import PostgresDsn, RedisDsn, computed_field, BaseModel
 from pydantic_core import MultiHostUrl
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
 
+class SMTPConfig(BaseModel):
+    server: str = os.getenv("EMAIL_HOST", "smtp_server")
+    port: int = os.getenv("EMAIL_PORT", 587)
+    username: str = os.getenv("EMAIL_HOST_USER", "smtp_user")
+    password: str = os.getenv("EMAIL_HOST_PASSWORD", "smtp_password")
+
+
 class Settings(BaseSettings):
     model_config = SettingsConfigDict(
         env_file=".env", env_ignore_empty=True, extra="ignore"
@@ -12,6 +19,8 @@ class Settings(BaseSettings):
     jwt_algorithm: str = os.getenv("JWT_ALGORITHM")
     jwt_expire: int = os.getenv("JWT_EXPIRE")
 
+    smtp: SMTPConfig = SMTPConfig()
+
     REDIS_HOST: str
     REDIS_PORT: int
     REDIS_DB: str

From 189158d31f72c7a81b87153dae3c742db569b519 Mon Sep 17 00:00:00 2001
From: grillazz <the@grillazz.com>
Date: Fri, 20 Dec 2024 18:06:37 +0100
Subject: [PATCH 3/3] init smtp service

---
 app/services/smtp.py | 54 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 app/services/smtp.py

diff --git a/app/services/smtp.py b/app/services/smtp.py
new file mode 100644
index 0000000..d4a2ce0
--- /dev/null
+++ b/app/services/smtp.py
@@ -0,0 +1,54 @@
+import smtplib
+from email.mime.multipart import MIMEMultipart
+from email.mime.text import MIMEText
+
+from app.config import settings as global_settings
+
+from fastapi.templating import Jinja2Templates
+
+from pydantic import EmailStr
+
+from app.utils.logging import AppLogger
+from app.utils.singleton import SingletonMetaNoArgs
+
+
+logger = AppLogger().get_logger()
+
+
+class SMTPEmailService(metaclass=SingletonMetaNoArgs):
+    def __init__(self):
+        self.server = smtplib.SMTP(
+            global_settings.smtp.server, global_settings.smtp.port
+        )
+        self.server.starttls()
+        self.server.login(global_settings.smtp.username, global_settings.smtp.password)
+        self.templates = Jinja2Templates("templates")
+
+    def send_email(
+        self,
+        sender: EmailStr,
+        recipients: list[EmailStr],
+        subject: str,
+        body_text: str = "",
+        body_html=None,
+    ):
+        msg = MIMEMultipart()
+        msg["From"] = sender
+        msg["To"] = ",".join(recipients)
+        msg["Subject"] = subject
+        msg.attach(MIMEText(body_text, "plain"))
+        if body_html:
+            msg.attach(MIMEText(body_html, "html"))
+        self.server.sendmail(sender, recipients, msg.as_string())
+
+    def send_template_email(
+        self,
+        recipients: list[EmailStr],
+        subject: str,
+        template: str = None,
+        context: dict = None,
+        sender: EmailStr = global_settings.smtp.from_email,
+    ):
+        template_str = self.templates.get_template(template)
+        body_html = template_str.render(context)
+        self.send_email(sender, recipients, subject, body_html=body_html)