# Payment Service API Documentation

**Base URL:** `/api/payment` (via gateway) or `http://localhost:8084` (direct)

**Service Port:** 8084

## Overview

The Payment Service handles all financial operations for the Coppertone.tech platform, including:

- Invoice management (create, read, update, delete)
- Payment processing via Stripe
- Multi-modal payment support (credit card, blockchain)
- Webhook handling for payment status updates
- IPFS document integration for invoice storage

## Authentication

All endpoints (except webhooks) require a valid JWT token:

```
Authorization: Bearer <jwt_token>
```

## Role-Based Access

| Role | Invoices | Payments | Payment Intent |
|------|----------|----------|----------------|
| `SUPERUSER` | Full access | Full access | Can create for any invoice |
| `ADMIN` | Full access | Full access | Can create for any invoice |
| `STAFF` | Full access | Full access | Can create for any invoice |
| `CLIENT` | Own invoices only | Own payments only | Own invoices only |

**Note:** `SUPERUSER` role automatically grants full access to all endpoints.

---

## Health Check

```
GET /healthz
```

**Response:**
```
200 OK
ok
```

---

## Invoices

### Invoice Statuses

| Status | Description |
|--------|-------------|
| `DRAFT` | Invoice created but not yet sent |
| `SENT` | Invoice sent to client |
| `PENDING` | Awaiting payment |
| `PAID` | Payment received |
| `OVERDUE` | Payment past due date |
| `CANCELLED` | Invoice cancelled |

### List Invoices

Retrieve invoices. CLIENTs see only their own invoices.

```
GET /invoices
GET /invoices?client_id=5
```

**Headers:**
```
Authorization: Bearer <token>
```

**Required Role:** Any authenticated user

**Query Parameters:**
| Parameter | Type | Description |
|-----------|------|-------------|
| `client_id` | integer | Optional (STAFF/ADMIN only). Filter by client |

**Response (200 OK):**
```json
[
  {
    "id": 1,
    "invoiceNumber": "INV-2024-001",
    "projectId": 1,
    "clientId": 5,
    "amount": 5000.00,
    "currency": "USD",
    "status": "PENDING",
    "dueDate": "2024-02-15",
    "issuedDate": "2024-01-15",
    "paidDate": null,
    "blockchainTxHash": null,
    "ipfsDocumentCid": "QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco",
    "notes": "Website redesign - Phase 1",
    "createdAt": "2024-01-15T10:00:00Z",
    "updatedAt": "2024-01-15T10:00:00Z"
  }
]
```

**Authorization Logic:**
- `STAFF/ADMIN/SUPERUSER`: See all invoices (optionally filtered by client_id)
- `CLIENT`: See only invoices where `client_id` matches their user ID

---

### Get Invoice by ID

Retrieve a single invoice.

```
GET /invoices/{id}
```

**Headers:**
```
Authorization: Bearer <token>
```

**Required Role:** Invoice owner (client_id) or `STAFF/ADMIN/SUPERUSER`

**Path Parameters:**
| Parameter | Type | Description |
|-----------|------|-------------|
| `id` | integer | Invoice ID |

**Response (200 OK):**
```json
{
  "id": 1,
  "invoiceNumber": "INV-2024-001",
  "projectId": 1,
  "clientId": 5,
  "amount": 5000.00,
  "currency": "USD",
  "status": "PENDING",
  "dueDate": "2024-02-15",
  "issuedDate": "2024-01-15",
  "paidDate": null,
  "blockchainTxHash": null,
  "ipfsDocumentCid": "QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco",
  "notes": "Website redesign - Phase 1",
  "createdAt": "2024-01-15T10:00:00Z",
  "updatedAt": "2024-01-15T10:00:00Z"
}
```

**Error Responses:**

| Status | Condition | Response |
|--------|-----------|----------|
| 400 | Invalid ID | `Invalid invoice ID` |
| 403 | No access | `Forbidden: you do not have access to this invoice` |
| 404 | Not found | `Invoice not found` |

---

### Create Invoice

Create a new invoice.

```
POST /invoices
```

**Headers:**
```
Authorization: Bearer <token>
```

**Required Role:** `STAFF`, `ADMIN`, or `SUPERUSER`

**Request Body:**
```json
{
  "invoiceNumber": "INV-2024-002",
  "projectId": 1,
  "clientId": 5,
  "amount": 2500.00,
  "currency": "USD",
  "status": "DRAFT",
  "dueDate": "2024-03-01",
  "issuedDate": "2024-02-01",
  "ipfsDocumentCid": "QmNewCid...",
  "notes": "Monthly retainer - February 2024"
}
```

| Field | Type | Required | Default | Description |
|-------|------|----------|---------|-------------|
| `invoiceNumber` | string | Yes | - | Unique invoice number |
| `clientId` | integer | Yes | - | Client user ID |
| `amount` | float | Yes | - | Invoice amount (must be > 0) |
| `projectId` | integer | No | - | Associated project ID |
| `currency` | string | No | `USD` | Currency code (ISO 4217) |
| `status` | string | No | `DRAFT` | Invoice status |
| `dueDate` | string | No | - | Due date (YYYY-MM-DD) |
| `issuedDate` | string | No | - | Issue date (YYYY-MM-DD) |
| `ipfsDocumentCid` | string | No | - | IPFS CID for invoice document |
| `notes` | string | No | - | Additional notes |

**Response (201 Created):**
```json
{
  "id": 2,
  "invoiceNumber": "INV-2024-002",
  "clientId": 5,
  "amount": 2500.00,
  "currency": "USD",
  "status": "DRAFT",
  ...
}
```

**Error Responses:**

| Status | Condition | Response |
|--------|-----------|----------|
| 400 | Missing fields | `Invoice number, client_id, and amount are required` |
| 403 | Insufficient role | `Insufficient permissions` |
| 409 | Duplicate number | `Invoice number already exists` |

---

### Update Invoice

Update an existing invoice.

```
PUT /invoices/{id}
```

**Headers:**
```
Authorization: Bearer <token>
```

**Required Role:** `STAFF`, `ADMIN`, or `SUPERUSER`

**Request Body:**
```json
{
  "invoiceNumber": "INV-2024-002",
  "projectId": 1,
  "clientId": 5,
  "amount": 2750.00,
  "currency": "USD",
  "status": "SENT",
  "dueDate": "2024-03-01",
  "issuedDate": "2024-02-01",
  "paidDate": null,
  "blockchainTxHash": null,
  "ipfsDocumentCid": "QmUpdatedCid...",
  "notes": "Updated notes"
}
```

**Response (200 OK):**
```json
{
  "id": 2,
  "invoiceNumber": "INV-2024-002",
  ...
}
```

**Error Responses:**

| Status | Condition | Response |
|--------|-----------|----------|
| 403 | Insufficient role | `Insufficient permissions` |
| 403 | Paid invoice | `Cannot modify a paid invoice` |
| 404 | Not found | `Invoice not found` |

**Business Rules:**
- **PAID invoices cannot be modified** - This protects financial audit trails
- Changes to paid invoices require issuing a credit note or new invoice

---

### Delete Invoice

Delete an invoice.

```
DELETE /invoices/{id}
```

**Headers:**
```
Authorization: Bearer <token>
```

**Required Role:** `STAFF`, `ADMIN`, or `SUPERUSER`

**Response (204 No Content)**

**Error Responses:**

| Status | Condition | Response |
|--------|-----------|----------|
| 403 | Insufficient role | `Insufficient permissions` |
| 403 | Paid invoice | `Cannot delete a paid invoice - it must be kept for audit purposes` |
| 404 | Not found | `Invoice not found` |

**Business Rules:**
- **PAID invoices cannot be deleted** - Required for financial audit compliance
- To "cancel" a paid invoice, issue a credit note instead

---

## Payments

### Payment Statuses

| Status | Description |
|--------|-------------|
| `PENDING` | Payment initiated, awaiting processing |
| `PROCESSING` | Payment being processed by gateway |
| `COMPLETED` | Payment successfully completed |
| `FAILED` | Payment failed |
| `REFUNDED` | Payment refunded |
| `CANCELLED` | Payment cancelled |

### Payment Methods

| Method | Description |
|--------|-------------|
| `CREDIT_CARD` | Credit/debit card via Stripe |
| `BANK_TRANSFER` | Direct bank transfer |
| `CRYPTO_ETH` | Ethereum cryptocurrency |
| `CRYPTO_BTC` | Bitcoin cryptocurrency |
| `CRYPTO_USDC` | USDC stablecoin |

### List Payments

Retrieve payments. CLIENTs see only payments for their invoices.

```
GET /payments
GET /payments?invoice_id=1
```

**Headers:**
```
Authorization: Bearer <token>
```

**Required Role:** Any authenticated user

**Query Parameters:**
| Parameter | Type | Description |
|-----------|------|-------------|
| `invoice_id` | integer | Optional. Filter by invoice |

**Response (200 OK):**
```json
[
  {
    "id": 1,
    "invoiceId": 1,
    "amount": 5000.00,
    "currency": "USD",
    "paymentMethod": "CREDIT_CARD",
    "status": "COMPLETED",
    "transactionId": "pi_3PGV9nLkdIwHu7ix0abcdefg",
    "blockchainTxHash": null,
    "blockchainNetwork": null,
    "paymentProcessor": "stripe",
    "processorFee": 145.00,
    "processedAt": "2024-01-20T14:30:00Z",
    "createdAt": "2024-01-20T14:25:00Z",
    "updatedAt": "2024-01-20T14:30:00Z"
  }
]
```

**Authorization Logic:**
- `STAFF/ADMIN/SUPERUSER`: See all payments (optionally filtered)
- `CLIENT`: See only payments for invoices where they are the client

---

### Get Payment by ID

Retrieve a single payment.

```
GET /payments/{id}
```

**Headers:**
```
Authorization: Bearer <token>
```

**Required Role:** Invoice owner or `STAFF/ADMIN/SUPERUSER`

**Response (200 OK):**
```json
{
  "id": 1,
  "invoiceId": 1,
  "amount": 5000.00,
  "currency": "USD",
  "paymentMethod": "CREDIT_CARD",
  "status": "COMPLETED",
  "transactionId": "pi_3PGV9nLkdIwHu7ix0abcdefg",
  "blockchainTxHash": null,
  "blockchainNetwork": null,
  "paymentProcessor": "stripe",
  "processorFee": 145.00,
  "processedAt": "2024-01-20T14:30:00Z",
  "createdAt": "2024-01-20T14:25:00Z",
  "updatedAt": "2024-01-20T14:30:00Z"
}
```

**Error Responses:**

| Status | Condition | Response |
|--------|-----------|----------|
| 403 | No access | `Forbidden: you do not have access to this payment` |
| 404 | Not found | `Payment not found` |

---

### Create Payment (Manual)

Create a manual payment record (for bank transfers, crypto, etc.).

```
POST /payments
```

**Headers:**
```
Authorization: Bearer <token>
```

**Required Role:** `STAFF`, `ADMIN`, or `SUPERUSER`

**Request Body:**
```json
{
  "invoiceId": 1,
  "amount": 5000.00,
  "currency": "USD",
  "paymentMethod": "BANK_TRANSFER",
  "status": "PENDING",
  "transactionId": "WIRE-2024-001",
  "blockchainTxHash": null,
  "blockchainNetwork": null,
  "paymentProcessor": null,
  "processorFee": null
}
```

| Field | Type | Required | Default | Description |
|-------|------|----------|---------|-------------|
| `invoiceId` | integer | Yes | - | Invoice being paid |
| `amount` | float | Yes | - | Payment amount (must be > 0) |
| `currency` | string | No | `USD` | Currency code |
| `paymentMethod` | string | No | - | Payment method |
| `status` | string | No | `PENDING` | Payment status |
| `transactionId` | string | No | - | External transaction ID |
| `blockchainTxHash` | string | No | - | Blockchain transaction hash |
| `blockchainNetwork` | string | No | - | Blockchain network (ethereum, bitcoin, etc.) |
| `paymentProcessor` | string | No | - | Payment processor name |
| `processorFee` | float | No | - | Processor fee amount |

**Response (201 Created):**
```json
{
  "id": 2,
  "invoiceId": 1,
  "amount": 5000.00,
  ...
}
```

---

## Stripe Integration

### Create Payment Intent

Create a Stripe payment intent for card payments.

```
POST /invoices/create-payment-intent
```

**Headers:**
```
Authorization: Bearer <token>
```

**Required Role:** Invoice owner (client_id) or `STAFF/ADMIN/SUPERUSER`

**Request Body:**
```json
{
  "invoiceId": 1
}
```

| Field | Type | Required | Description |
|-------|------|----------|-------------|
| `invoiceId` | integer | Yes | Invoice to pay |

**Response (200 OK):**
```json
{
  "clientSecret": "pi_3PGV9nLkdIwHu7ix_secret_abc123...",
  "paymentId": 3
}
```

| Field | Type | Description |
|-------|------|-------------|
| `clientSecret` | string | Stripe client secret for frontend payment form |
| `paymentId` | integer | Database payment record ID |

**Error Responses:**

| Status | Condition | Response |
|--------|-----------|----------|
| 403 | Not invoice owner | `Forbidden: you can only pay your own invoices` |
| 404 | Invoice not found | `Invoice not found` |
| 503 | Stripe not configured | `Stripe not configured` |

**Frontend Integration:**

Use the `clientSecret` with Stripe.js to complete the payment:

```javascript
// Initialize Stripe
const stripe = Stripe('pk_test_...');

// Create payment element
const elements = stripe.elements({ clientSecret });
const paymentElement = elements.create('payment');
paymentElement.mount('#payment-element');

// Submit payment
const { error } = await stripe.confirmPayment({
  elements,
  confirmParams: {
    return_url: 'https://coppertone.tech/payment/success',
  },
});
```

---

## Webhooks

### Stripe Webhook

Receive Stripe webhook events for payment status updates.

```
POST /webhooks/stripe
```

**Authentication:** Stripe webhook signature verification (not JWT)

**Headers:**
```
Stripe-Signature: t=...,v1=...,v0=...
```

**Handled Events:**

| Event | Action |
|-------|--------|
| `payment_intent.succeeded` | Update payment status to `COMPLETED`, update invoice to `PAID` |
| `payment_intent.payment_failed` | Update payment status to `FAILED` |
| `charge.refunded` | Update payment status to `REFUNDED` |

**Response (200 OK):**
```json
{
  "received": true
}
```

**Error Responses:**

| Status | Condition | Response |
|--------|-----------|----------|
| 400 | Invalid signature | `Invalid webhook signature` |
| 503 | Webhook secret not configured | `Service configuration error` |

**Webhook Configuration:**

1. In Stripe Dashboard, create a webhook endpoint pointing to:
   ```
   https://your-domain.com/api/payment/webhooks/stripe
   ```

2. Select events:
   - `payment_intent.succeeded`
   - `payment_intent.payment_failed`
   - `charge.refunded`

3. Copy the webhook signing secret and set as environment variable:
   ```
   STRIPE_WEBHOOK_SECRET=whsec_...
   ```

---

## CORS Configuration

Same as other services:

| Header | Value |
|--------|-------|
| `Access-Control-Allow-Origin` | Configured via `CORS_ALLOW_ORIGIN` env var |
| `Access-Control-Allow-Methods` | `GET, POST, PUT, DELETE, OPTIONS` |
| `Access-Control-Allow-Headers` | `Content-Type, Authorization` |
| `Access-Control-Allow-Credentials` | `true` |

---

## Environment Variables

| Variable | Required | Default | Description |
|----------|----------|---------|-------------|
| `JWT_SECRET` | Yes | - | Secret key for JWT validation |
| `DB_HOST` | Yes | - | PostgreSQL host |
| `DB_USER` | Yes | - | PostgreSQL user |
| `DB_PASSWORD` | Yes | - | PostgreSQL password |
| `DB_NAME` | Yes | - | PostgreSQL database name |
| `DB_SSL_MODE` | No | `require` | SSL mode |
| `DB_SCHEMA` | No | `public` | Schema: `dev`, `testing`, `prod` |
| `STRIPE_SECRET_KEY` | No | - | Stripe secret API key (sk_...) |
| `STRIPE_WEBHOOK_SECRET` | No | - | Stripe webhook signing secret (whsec_...) |
| `CORS_ALLOW_ORIGIN` | No | `http://localhost:8090` | Allowed CORS origin |

**Note:** If `STRIPE_SECRET_KEY` is not set, Stripe functionality will be disabled.

---

## Database Tables

### invoices
```sql
CREATE TABLE invoices (
    id SERIAL PRIMARY KEY,
    invoice_number VARCHAR(50) NOT NULL UNIQUE,
    project_id INTEGER REFERENCES projects(id),
    client_id INTEGER NOT NULL REFERENCES users(id),
    amount DECIMAL(12,2) NOT NULL,
    currency VARCHAR(3) DEFAULT 'USD',
    status VARCHAR(20) DEFAULT 'DRAFT',
    due_date DATE,
    issued_date DATE,
    paid_date DATE,
    blockchain_tx_hash VARCHAR(100),
    ipfs_document_cid VARCHAR(100),
    notes TEXT,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);
```

### payments
```sql
CREATE TABLE payments (
    id SERIAL PRIMARY KEY,
    invoice_id INTEGER NOT NULL REFERENCES invoices(id),
    amount DECIMAL(12,2) NOT NULL,
    currency VARCHAR(3) DEFAULT 'USD',
    payment_method VARCHAR(50),
    status VARCHAR(20) DEFAULT 'PENDING',
    transaction_id VARCHAR(100),
    blockchain_tx_hash VARCHAR(100),
    blockchain_network VARCHAR(50),
    payment_processor VARCHAR(50),
    processor_fee DECIMAL(10,2),
    processed_at TIMESTAMP,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);
```

---

## Security Considerations

1. **Stripe Webhook Verification**: All webhook requests are verified using Stripe's signature verification
2. **PAID Invoice Protection**: Paid invoices cannot be modified or deleted (audit trail)
3. **Authorization Checks**: All endpoints verify user ownership or elevated role
4. **SQL Injection Prevention**: All queries use parameterized statements
5. **PCI Compliance**: Card data never touches our servers - handled entirely by Stripe
6. **Amount Validation**: All amounts must be positive numbers