import fs from 'fs'
import path from 'path'

export default defineEventHandler(async (event) => {
  try {
    // Set appropriate headers for JSON response
    setHeader(event, 'Content-Type', 'application/json')
    setHeader(event, 'Cache-Control', 'public, max-age=300') // Cache for 5 minutes
    
    // Read the custom OpenAPI JSON file
    const openApiPath = path.join(process.cwd(), 'docs', 'openapi-custom.json')
    
    if (!fs.existsSync(openApiPath)) {
      throw createError({
        statusCode: 404,
        statusMessage: 'Custom OpenAPI specification not found. Please create it first from the configuration panel.'
      })
    }
    
    const openApiContent = fs.readFileSync(openApiPath, 'utf-8')
    const openApiSpec = JSON.parse(openApiContent)
    
    // Dynamically update server URLs based on the current request
    const host = getHeader(event, 'host') || 'localhost:3000'
    const protocol = getHeader(event, 'x-forwarded-proto') || 
                    (host.includes('localhost') || host.includes('127.0.0.1') ? 'http' : 'https')
    
    // Update servers in the OpenAPI spec if they don't exist or need updating
    if (!openApiSpec.servers || openApiSpec.servers.length === 0) {
      openApiSpec.servers = [
        {
          url: `${protocol}://${host}/api`,
          description: 'Current Server'
        },
        {
          url: "http://localhost:3000/api",
          description: "Development Server"
        },
        {
          url: "{protocol}://{host}:{port}/api",
          description: "Configurable Server",
          variables: {
            protocol: {
              enum: ["http", "https"],
              default: protocol
            },
            host: {
              default: host.split(':')[0]
            },
            port: {
              default: host.includes(':') ? host.split(':')[1] : (protocol === 'https' ? '443' : '80')
            }
          }
        }
      ]
    }
    
    return openApiSpec
    
  } catch (error) {
    console.error('Error serving Custom OpenAPI specification:', error)
    
    throw createError({
      statusCode: 500,
      statusMessage: 'Failed to load Custom OpenAPI specification',
      data: {
        error: error.message
      }
    })
  }
})