VerifactuMidAPI/documentacion/PREREQUISITES.md

# Prerequisites

## System Requirements

### Go

- **Version:** 1.26 or higher
- **Download:** https://go.dev/dl/
- **Verify installation:**
  ```bash
  go version
  ```

No se requieren Python, OpenSSL ni scripts externos. Todo el procesamiento de certificados (.p12/.pfx) es nativo en Go.

---

## Project Setup

### 1. Clone the repository

```bash
git clone <repository-url>
cd VerifactuMidAPI
```

### 2. Install Go dependencies

```bash
go mod download
```

### 3. Create required directories

```bash
mkdir -p data/certs data keys
```

| Directory | Purpose |
|---|---|
| `data/certs/` | Stored `.p12` certificates |
| `data/` | Hash chain records (JSON files per emitter) |
| `keys/` | Auto-generated RSA key pair for password encryption |

### 4. Configure the application

Copy or edit `config.yml`:

```yaml
server:
  port: 6789

verifactu:
  production: false

certificates:
  storage_path: ./data/certs/
  cert_file: ./data/certs/personal.p12
  cert_password: YOUR_PASSWORD

crypto:
  keys_path: ./keys/
  name: "VeriFactu API"
  email: "admin@example.com"
```

> **Important:** Change `cert_password` and `email` to your own values.

### 5. Obtain a digital certificate

VeriFactu requires a **qualified electronic certificate** (eIDAS compliant) in `.p12` or `.pfx` format.

- **FNMT Persona Fisica** (free): https://www.fnmt.es
- Must be valid and registered with AEAT for the testing environment
- Place it at `./data/certs/personal.p12` (or update `cert_file` in config)

---

## Build & Run

### Development (auto-reload with source)

```bash
go run .
```

### Production build

```bash
go build -o verifactu-api .
./verifactu-api
```

The server starts on `http://localhost:6789` (or the port configured in `config.yml`).

---

## Verify the installation

### 1. Health check

```bash
curl http://localhost:6789/api/v1/health
# Expected: {"status":"ok"}
```

### 2. Get public key

```bash
curl http://localhost:6789/api/v1/auth/public-key
# Expected: {"public_key":"<base64>"}
```

---

## Troubleshooting

### `go: command not found`

Go is not installed or not in your `PATH`. Add it:

```bash
# Linux/macOS
export PATH=$PATH:/usr/local/go/bin

# Windows: add C:\Program Files\Go\bin to system PATH
```

### `config.yml not found`

The API falls back to defaults but logs a warning. Create the file as described in step 4.

### `certificate expired` / `invalid_password_or_format`

- Verify the certificate dates with:
  ```bash
  openssl pkcs12 -in ./data/certs/personal.p12 -info -nokeys
  ```
- Ensure the password in `config.yml` matches the certificate.

### `403 Forbidden` from AEAT

The certificate is not authorized in the AEAT testing environment. Contact AEAT or verify your FNMT certificate is enabled for VeriFactu.