import { Compiler } from 'webpack'
import webpack from 'webpack'
const isWebpack5 = parseInt(webpack.version!) === 5

const GraphHelpers = isWebpack5
  ? undefined
  : require('webpack/lib/GraphHelpers')

/**
 * Makes sure there are no dynamic chunks when the target is serverless
 * The dynamic chunks are integrated back into their parent chunk
 * This is to make sure there is a single render bundle instead of that bundle importing dynamic chunks
 */

export class ServerlessPlugin {
  apply(compiler: Compiler) {
    compiler.hooks.compilation.tap('ServerlessPlugin', (compilation) => {
      const hook = isWebpack5
        ? compilation.hooks.optimizeChunks
        : compilation.hooks.optimizeChunksBasic

      hook.tap('ServerlessPlugin', (chunks) => {
        for (const chunk of chunks) {
          // If chunk is not an entry point skip them
          if (!chunk.hasEntryModule()) {
            continue
          }

          // Async chunks are usages of import() for example
          const dynamicChunks = chunk.getAllAsyncChunks()
          for (const dynamicChunk of dynamicChunks) {
            for (const module of dynamicChunk.modulesIterable) {
              if (isWebpack5) {
                // Add module back into the entry chunk
                chunk.addModule(module)
                continue
              }

              // Webpack 4 has separate GraphHelpers
              GraphHelpers.connectChunkAndModule(chunk, module)
            }
          }
        }
      })
    })
  }
}