### Install ALTCHA Dependencies

Source: https://context7.com/altcha-org/tutorials/llms.txt

Install the necessary ALTCHA packages and the Astro Node adapter for server-side rendering. Then, start the development server.

```bash
# Install ALTCHA packages
npm install altcha altcha-lib

# Install Astro Node adapter for server-side rendering
npm install @astrojs/node

# Start development server
npm run dev

```

--------------------------------

### Start development server

Source: https://github.com/altcha-org/tutorials/blob/main/invisible-captcha/README.md

Execute this command to launch the local development server.

```sh
bun run dev
```

--------------------------------

### Install project dependencies

Source: https://github.com/altcha-org/tutorials/blob/main/invisible-captcha/README.md

Run this command to install all required packages defined in the project configuration.

```sh
bun install
```

--------------------------------

### Start the development server

Source: https://github.com/altcha-org/tutorials/blob/main/astro/README.md

Run this command in the terminal to launch the local development environment.

```bash
npm run dev
```

--------------------------------

### Install Dependencies for Invisible Captcha Server

Source: https://context7.com/altcha-org/tutorials/llms.txt

Navigate to the 'invisible-captcha' directory and run this command to install project dependencies using Bun.

```bash
# Navigate to invisible-captcha directory
cd invisible-captcha

# Install dependencies
bun install
```

--------------------------------

### Start Invisible Captcha Development Server

Source: https://context7.com/altcha-org/tutorials/llms.txt

Run this command to start the Hono-based spam filter server with hot reloading using Bun. The server will be accessible at http://localhost:3000.

```bash
# Start development server with hot reloading
bun run dev
```

--------------------------------

### Invisible Captcha with Spam Filter API using Hono

Source: https://context7.com/altcha-org/tutorials/llms.txt

Use the ALTCHA Spam Filter API with Hono and Bun runtime for server-side content classification. This example classifies form submissions without a visible widget and requires API keys and referrer configuration.

```typescript
// src/index.ts
import { Hono } from 'hono';

const API_KEY = 'ckey_your_api_key_here';
const REFERRER = 'https://yourdomain.com/';

const app = new Hono();

async function makeSpamFilterRequest(
  body: {
    email?: string;
    fields?: Record<string, string>;
    ipAddress?: string;
  }
) {
  const resp = await fetch(`https://eu.altcha.org/api/v1/classify?apiKey=${API_KEY}`, {
    body: JSON.stringify(body),
    headers: {
      'content-type': 'application/json',
      'referer': REFERRER
    },
    method: 'POST',
  });

  if (resp.status !== 200) {
    throw new Error('Unexpected server response');
  }

  return resp.json();
}

app.get('/', (c) => {
  return c.text('Hello Hono!');
});

app.post('/submit', async (c) => {
  const ipAddress = c.req.header('x-forwarded-for')?.split(',')[0];
  const body = await c.req.parseBody();

  const { classification } = await makeSpamFilterRequest({
    email: String(body.email),
    fields: {
      name: String(body.name),
      message: String(body.message),
    },
    ipAddress,
  });

  if (classification === 'BAD') {
    return c.json({
      error: 'Cannot submit spam.',
      success: false,
    }, 400);
  }

  // Process legitimate submissions
  return c.json({
    success: true,
  });
});

export default app;

```

--------------------------------

### Fetch Challenge from ALTCHA API

Source: https://context7.com/altcha-org/tutorials/llms.txt

Use this cURL command to fetch a proof-of-work challenge from the ALTCHA API. Replace 'ckey_your_api_key_here' with your actual API key. The response includes algorithm, challenge, salt, and signature details.

```bash
# Fetch a challenge from ALTCHA API
curl -X GET "https://eu.altcha.org/api/v1/challenge?apiKey=ckey_your_api_key_here"
```

--------------------------------

### Astro Configuration for Server-Side Rendering

Source: https://context7.com/altcha-org/tutorials/llms.txt

Configure Astro with the Node adapter in standalone mode to enable POST request handling, which is necessary for server-side ALTCHA verification.

```javascript
// astro.config.mjs
import { defineConfig } from 'astro/config';
import node from "@astrojs/node";

export default defineConfig({
  output: "server",
  adapter: node({
    mode: "standalone"
  })
});

```

--------------------------------

### ALTCHA Widget Integration with Astro

Source: https://context7.com/altcha-org/tutorials/llms.txt

Embed the ALTCHA widget in an Astro page for client-side challenge and verify the solution server-side using altcha-lib. Requires API keys for configuration.

```astro
---
// src/pages/index.astro
import { verifySolution } from "altcha-lib";

// Configure your own API Key: https://altcha.org/docs/api/api_keys
const ALTCHA_API_KEY = "ckey_your_api_key_here";
const ALTCHA_API_SECRET = "csec_your_api_secret_here";

if (Astro.request.method === "POST") {
  try {
    const data = await Astro.request.formData();
    const altchaPayload = data.get("altcha")?.toString();

    if (!altchaPayload) {
      throw new Error("Altcha payload missing.");
    }

    if (await verifySolution(altchaPayload, ALTCHA_API_SECRET)) {
      console.log('Verification successful', Object.fromEntries(data));
      // Process form data here
    } else {
      console.log('Verification failed');
      // Handle verification failure
    }
  } catch (error) {
    if (error instanceof Error) {
      console.error(error.message);
    }
  }
}
---

<script>
  import('altcha');
</script>

<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width" />
    <title>ALTCHA Form Example</title>
  </head>
  <body>
    <form method="POST">
      <div>
        <label for="email">Email:</label>
        <input type="email" name="email" id="email" required />
      </div>

      <div>
        <label for="message">Message:</label>
        <textarea name="message" rows="4" required></textarea>
      </div>

      <div>
        <altcha-widget
          challengeurl={`https://eu.altcha.org/api/v1/challenge?apiKey=${ALTCHA_API_KEY}`}
        ></altcha-widget>
      </div>

      <button type="submit">Submit</button>
    </form>
  </body>
</html>

```

--------------------------------

### Submit Content for Spam Classification

Source: https://context7.com/altcha-org/tutorials/llms.txt

Submit form content to the ALTCHA Classify API for spam detection. This cURL command includes email, fields, and IP address in JSON format. Ensure to set the correct Content-Type and Referer headers. The response indicates if the content is classified as 'GOOD' or 'BAD'.

```bash
# Submit content for spam classification
curl -X POST "https://eu.altcha.org/api/v1/classify?apiKey=ckey_your_api_key_here" \
  -H "Content-Type: application/json" \
  -H "Referer: https://yourdomain.com/" \
  -d '{
    "email": "user@example.com",
    "fields": {
      "name": "John Doe",
      "message": "Hello, I would like to inquire about your services."
    },
    "ipAddress": "192.168.1.1"
  }'
```

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