Flux Kontext API Quickstart

class FluxKontextAPI {
  constructor(apiKey) {
    this.apiKey = apiKey;
    this.baseUrl = 'https://api.kie.ai/api/v1/flux/kontext';
  }
  
  async generateImage(prompt, options = {}) {
    const response = await fetch(`${this.baseUrl}/generate`, {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${this.apiKey}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        prompt,
        aspectRatio: options.aspectRatio || '16:9',
        model: options.model || 'flux-kontext-pro',
        enableTranslation: options.enableTranslation !== false,
        outputFormat: options.outputFormat || 'jpeg',
        ...options
      })
    });
    
    const result = await response.json();
    if (!response.ok || result.code !== 200) {
      throw new Error(`Generation failed: ${result.msg || 'Unknown error'}`);
    }
    
    return result.data.taskId;
  }
  
  async editImage(prompt, inputImage, options = {}) {
    return this.generateImage(prompt, {
      ...options,
      inputImage
    });
  }
  
  async waitForCompletion(taskId, maxWaitTime = 300000) { // 5 minutes max
    const startTime = Date.now();
    
    while (Date.now() - startTime < maxWaitTime) {
      const status = await this.getTaskStatus(taskId);
      
      switch (status.successFlag) {
        case 0:
          console.log('Task is generating, continue waiting...');
          break;
          
        case 1:
          console.log('Generation completed successfully!');
          return status.response;
          
        case 2:
          const createError = status.errorMessage || 'Create task failed';
          console.error('Create task failed:', createError);
          if (status.errorCode) {
            console.error('Error code:', status.errorCode);
          }
          throw new Error(createError);
          
        case 3:
          const generateError = status.errorMessage || 'Generation failed';
          console.error('Generation failed:', generateError);
          if (status.errorCode) {
            console.error('Error code:', status.errorCode);
          }
          throw new Error(generateError);
          
        default:
          console.log(`Unknown status: ${status.successFlag}`);
          if (status.errorMessage) {
            console.error('Error message:', status.errorMessage);
          }
          break;
      }
      
      // Wait 3 seconds before next check
      await new Promise(resolve => setTimeout(resolve, 3000));
    }
    
    throw new Error('Generation timeout');
  }
  
  async getTaskStatus(taskId) {
    const response = await fetch(`${this.baseUrl}/record-info?taskId=${taskId}`, {
      method: 'GET',
      headers: {
        'Authorization': `Bearer ${this.apiKey}`
      }
    });
    
    const result = await response.json();
    if (!response.ok || result.code !== 200) {
      throw new Error(`Status check failed: ${result.msg || 'Unknown error'}`);
    }
    
    return result.data;
  }
}

// Usage Example
async function main() {
  const api = new FluxKontextAPI('YOUR_API_KEY');
  
  try {
    // Text-to-Image Generation
    console.log('Starting image generation...');
    const taskId = await api.generateImage(
      'A futuristic cityscape at night with neon lights and flying cars',
      { 
        aspectRatio: '16:9',
        model: 'flux-kontext-max',
        promptUpsampling: true
      }
    );
    
    // Wait for completion
    console.log(`Task ID: ${taskId}. Waiting for completion...`);
    const result = await api.waitForCompletion(taskId);
    
    console.log('Image generated successfully!');
    console.log('Result Image URL:', result.resultImageUrl);
    console.log('Original Image URL (valid 10 min):', result.originImageUrl);
    
    // Image Editing Example
    console.log('\nStarting image editing...');
    const editTaskId = await api.editImage(
      'Add rainbow in the sky',
      result.resultImageUrl,
      { aspectRatio: '16:9' }
    );
    
    const editResult = await api.waitForCompletion(editTaskId);
    console.log('Image edited successfully!');
    console.log('Edited Image URL:', editResult.resultImageUrl);
    
  } catch (error) {
    console.error('Error:', error.message);
  }
}

main();