📚 LIBR Simplified Prototype

A very minimal simulation of the LIBR system implementing decentralized moderation using Go concurrency, PostgreSQL, and RESTful APIs.

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🚀 Objective

Simulate decentralized moderation using goroutines, channels, and context timeouts. Provide basic APIs for:

• Submitting a message (POST /submit)
• Retrieving messages by timestamp (GET /fetch/{timestamp})
• Retrieve all stored messages regardless of timestamp (GET /fetchall)

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📁 Folder Structure

LIBR Prototype/
├── cmd/
│   └── main.go                 # Starts the server
├── controllers/
│   └── handler.go              # HTTP handler logic
├── db/
│   ├── db.go                   # DB connection setup
│   └── message_repo.go         # DB operations
├── moderator/
│   └── moderator.go            # Simulates moderation with goroutines
├── model/
│   └── message.go              # Data models
├── router/
│   └── router.go               # Route registration
├── .env                        # PostgreSQL credentials
├── go.mod                      # Module file
└── README.md

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🔧 Setup Instructions

1️⃣ Install PostgreSQL

sudo apt update
sudo apt install postgresql postgresql-contrib

2️⃣ Create the Database & Table

CREATE DATABASE libr;

\c libr

CREATE TABLE messages (
  id UUID PRIMARY KEY,
  content TEXT NOT NULL,
  timestamp BIGINT NOT NULL,
  status VARCHAR(10) NOT NULL
);

3️⃣ Configure Environment Variables

Create a .env file in the root directory:

DB_URL=

Replace credentials with yours if needed.

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🛠 Installation

git clone <your-repo-url>
cd "LIBR Prototype"

go mod tidy
go build -o server ./cmd
./server

Server will start on: http://localhost:4000

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🌐 API Endpoints

📨 POST /submit

Submit a message for moderation.

Request Payload:

{
  "content": "This is a test message."
}

Sample Response (Approved):

{
  "id": "generated-uuid",
  "timestamp": 1744219507,
  "status": "approved"
}

Sample Response (Rejected):

{
  "id": "generated-uuid",
  "timestamp": 1744219507,
  "status": "rejected"
}

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📥 GET /fetch/{timestamp}

Retrieve all messages submitted at a specific timestamp.

Sample Response:

[
  {
    "id": "unique-id",
    "content": "This is a test message.",
    "timestamp": 1744219507,
    "status": "approved"
  }
]

📥 GET /fetch

Retrieve all messages regardless of timestamp.

Sample Response:

[
  {
    "id": "unique-id",
    "content": "This is a test message.",
    "timestamp": 1744219507,
    "status": "approved"
  }
  {
    "id": "unique-id",
    "content": "This is a test message.",
    "timestamp": 1744219507,
    "status": "approved"
  }
  {
    "id": "unique-id",
    "content": "This is a test message.",
    "timestamp": 1744219507,
    "status": "approved"
  }
]

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🧠 Simulated Moderation

Each message is sent to 3 simulated moderators. Moderators:

• Use goroutines for concurrency.
• Introduce random delays (1-3s) to mimic real processing.
• Randomly approve/reject the message.
• Respond via channels.
• Have a 3s timeout using context.WithTimeout.

The message is approved if at least 2 moderators approve, otherwise it's rejected.

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🛠 Libraries Used

• gorilla/mux: Routing
• pgx: PostgreSQL driver
• google/uuid: UUID generator
• joho/godotenv: Load environment variables

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📸 Screenshots

✅ Successful Submit (Postman)

❌ Rejected Submit

📤 Fetch All Messages

📤 Fetch Messages

📤 Try Fetching Rejected Messages

🧪 Testing

Use Postman to test:

🔐 Security Note

• DB credentials are stored in .env. Do not commit .env to version control.
• This is a prototype. Avoid using it in production environments.

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