Saheb App Design System

1. Purpose of This Documentation

This presentation explains the design and technical decisions behind our application features.

a. We will be covering:

1. Technology Stack

Backend framework
Web frontend framework
Mobile frontend framework
Database technology (PostgreSQL, MySQL, etc.)
UI libraries
Supporting libraries and tools (state management, datafetching, utilities)

2. Application Architecture & Project Structure

Backend folder structure
Frontend folder structure
Design patterns and development strategies

3. Localization & Language Support

Multi-language database translation strategy
RTL (Right-to-Left) support on web and mobile
Hijri calendar localization

4. Core Domain Logic

Qibla calculation logic
Prayer time calculation methods
Hijri time caulculation methods

5. Media Management

Audio resource handling (Sermon / موعظة)
Video hosting and streaming strategy

6. Notifications & Communication

Timezone-aware push notification system
Email notification architecture
Notification reliability and crash handling
Scheduling notificaiton with cron

8. Application Standards

Request logging
User event and activity tracking
Error and crash reporting
API versioning

b. How Each Section Is Documented

For every section in this documentation, we consistently answer the following questions:

What solution did we choose?
Why did we choose this solution?
What are the pros (optional) and cons of this solution?
What alternative approaches were considered?

1. Technology Stack

a. Backend Framework

What solution did we choose?
We chose Nodejs + Expressjs + NestJS as the backend framework.

Why did we choose this solution?

Team is more experienced with
Widely used on our code base
Built with TypeScript by default

Pros

Clear module-based architecture
Strong TypeScript support
Easy integration with databases, authentication, and queues
Express Rich community
Supports modular development and scalability
Fits well for APIs serving web and mobile apps
One backend server for both mobile and web

Cons

Slightly more boilerplate
Integration Complexity with Some Legacy Libraries

Alternative Approaches

Express.js
Fastify
Laravel (PHP)
Spring Boot (Java)

b. Web Frontend Framework

What solution did we choose?
We chose Next.js using the App Directory.

Why did we choose this solution?

Built-in support for modern React features
File-based routing with the App Directory
Good integration with backend APIs
Built-in layouts, and loading states, server errors handlings

Pros

Clear and scalable project structure
Server-side rendering and static generation
Strong support for SEO and web performance
Server Components

Cons

Some ecosystem libraries are still adapting
Build & Deployment Complexity
Rapidly Changing Features

Alternative Approaches

React ( Vite )
React (Tanstack start )
Nuxt.js
Angular

c. Mobile Frontend Framework

What solution did we choose?
We chose React Native with Expo.

Why did we choose this solution?

Allows building iOS Android apps and web from a single codebase
Quick testing on simulators, emulators, and real devices
Built-in support for push notifications, sensors, and device APIs
Large community and ecosystem
Deployment built-in (EAS Hosting)
Routing and Authentification built in
Assets management
AI intergration (expo mcp server)

Cons

Some native modules require custom development (Ejecting from Expo)

Alternative Approaches

Pure React Native (without Expo)
Flutter
Native iOS (Swift) / Android (Kotlin) development

d. Database Technology

What solution did we choose?
We chose PostgreSQL as the database for our application.

Why did we choose this solution?

Team is more experienced with
Good ecosystem and tooling support
Reliable and stable relational database
Widely used in the industry with large community and resources
Works well with TypeORM for Nestjs integration

Pros

Good ecosystem and tooling support
Open-source and actively maintained
Supports advanced features like JSON, full-text search, and indexes
Strong support for transactions

Cons

Can be more complex to set up than simpler databases (like SQLite)
Overkill for very small projects

e. UI Libraries

1. Web Frontend component library

What solution did we choose?
We chose shadcn/ui integrated with Tailwind CSS, and Figma designs for reference.

Why did we choose this solution?

Tailwind provide CSS utility classes to speed up development, so instead of writing custom CSS files, we style components directly using small, reusable classes

Without Tailwind (Traditional CSS):

```
<button class="btn">
  Save
</button>
```

.btn {
  background-color: blue;
  color: white;
  padding: 8px 16px;
  border-radius: 6px;
}

With Tailwind:

<button class="bg-blue-600 text-white px-4 py-2 rounded-md">
  Save
</button>

Provides a ready-to-use component library built on Tailwind CSS
~~Tailwind~~

~~allows~~

~~fast~~

~~and consistent styling~~ ~~across the app~~

Open Code: The top layer of your component code is open for modification

import * as React from "react"
import { Slot } from "@radix-ui/react-slot"
import { cva, type VariantProps } from "class-variance-authority"

import { cn } from "@/lib/utils"

const buttonVariants = cva(
  "inline-flex items-center justify-center gap-2 whitespace-nowrap rounded-md text-sm font-medium transition-all disabled:pointer-events-none disabled:opacity-50 [&_svg]:pointer-events-none [&_svg:not([class*='size-'])]:size-4 shrink-0 [&_svg]:shrink-0 outline-none focus-visible:border-ring focus-visible:ring-ring/50 focus-visible:ring-[3px] aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 aria-invalid:border-destructive",
  {
    variants: {
      variant: {
        default: "bg-primary text-primary-foreground hover:bg-primary/90",
        destructive:
          "bg-destructive text-white hover:bg-destructive/90 focus-visible:ring-destructive/20 dark:focus-visible:ring-destructive/40 dark:bg-destructive/60",
        outline:
          "border bg-background shadow-xs hover:bg-accent hover:text-accent-foreground dark:bg-input/30 dark:border-input dark:hover:bg-input/50",
        secondary:
          "bg-secondary text-secondary-foreground hover:bg-secondary/80",
        ghost:
          "hover:bg-accent hover:text-accent-foreground dark:hover:bg-accent/50",
        link: "text-primary underline-offset-4 hover:underline",
      },
      size: {
        default: "h-9 px-4 py-2 has-[>svg]:px-3",
        sm: "h-8 rounded-md gap-1.5 px-3 has-[>svg]:px-2.5",
        lg: "h-10 rounded-md px-6 has-[>svg]:px-4",
        icon: "size-9",
        "icon-sm": "size-8",
        "icon-lg": "size-10",
      },
    },
    defaultVariants: {
      variant: "default",
      size: "default",
    },
  }
)

function Button({
  className,
  variant = "default",
  size = "default",
  asChild = false,
  ...props
}: React.ComponentProps<"button"> &
  VariantProps<typeof buttonVariants> & {
    asChild?: boolean
  }) {
  const Comp = asChild ? Slot : "button"

  return (
    <Comp
      data-slot="button"
      data-variant={variant}
      data-size={size}
      className={cn(buttonVariants({ variant, size, className }))}
      {...props}
    />
  )
}

export { Button, buttonVariants }

Distribution: A flat-file schema and command-line tool make it easy to distribute components.
- ```
npx shadcn@latest add button
```

AI-Ready: Open code for LLMs to read, understand, and improve (mcp server).
- ```
{
  "registries": {
    "@acme": "https://acme.com/r/{name}.json"
  }
}
```
Figma designs give a visual reference for UI consistency
Huge ecosystem built around shadcn.
Fits well with React and Next.js
Very customizable :
1. you can change the whole app theme by changing only globall.css file :
  - tweakcn
2. change component source code.

Pros

Lightweight and modern styling approach

Cons

Learning curve for Tailwind if new to utility-first CSS

Alternative Approaches

Material-UI (MUI)
Ant Design
Chakra UI
Custom components from scratch