import { defineConfig, type PluginOption } from 'vite'
import react from '@vitejs/plugin-react'
import path from 'path'
import fs from 'fs'

// SPA fallback middleware - runs after Vite's built-in middleware
function spaFallback(): PluginOption {
  return {
    name: 'spa-fallback',
    configureServer(server) {
      // Return a function to execute after Vite's internal middleware
      return () => {
        server.middlewares.use((req, res, next) => {
          // Skip API routes and file requests
          if (req.url?.startsWith('/api') || req.url?.includes('.')) {
            return next()
          }

          // Serve index.html for SPA routes
          const indexPath = path.resolve(__dirname, 'index.html')
          if (fs.existsSync(indexPath)) {
            res.statusCode = 200
            res.setHeader('Content-Type', 'text/html')
            let html = fs.readFileSync(indexPath, 'utf-8')
            server.transformIndexHtml(req.url || '/', html).then(transformed => {
              res.end(transformed)
            }).catch(next)
          } else {
            next()
          }
        })
      }
    },
    configurePreviewServer(server) {
      // Same logic for preview server
      server.middlewares.use((req, res, next) => {
        if (req.url?.startsWith('/api') || req.url?.includes('.')) {
          return next()
        }

        const indexPath = path.resolve(__dirname, 'dist/client/index.html')
        if (fs.existsSync(indexPath)) {
          res.statusCode = 200
          res.setHeader('Content-Type', 'text/html')
          res.end(fs.readFileSync(indexPath, 'utf-8'))
        } else {
          next()
        }
      })
    }
  }
}

export default defineConfig({
  plugins: [react(), spaFallback()],
  root: '.',
  publicDir: 'public',
  build: {
    outDir: 'dist/client',
  },
  server: {
    host: '0.0.0.0',
    proxy: {
      '/api': {
        target: 'http://localhost:3000',
        changeOrigin: true,
      },
    },
  },
  preview: {
    host: '0.0.0.0',
  },
  resolve: {
    alias: {
      '@': path.resolve(__dirname, 'src/client'),
      '@shared': path.resolve(__dirname, 'src/shared'),
    },
  },
})