online_formatter/src/main/kotlin/main.kt

/*
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.facebook.ktfmt.onlineformatter

import com.amazonaws.services.lambda.runtime.Context
import com.amazonaws.services.lambda.runtime.RequestHandler
import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent
import com.facebook.ktfmt.KOTLINLANG_FORMAT
import com.facebook.ktfmt.format
import com.facebook.ktfmt.parseOptions
import com.google.gson.Gson
import java.io.ByteArrayOutputStream
import java.io.PrintStream

class Handler : RequestHandler<APIGatewayProxyRequestEvent, String> {
  init {
    // Warm up.
    gson.toJson(format(KOTLINLANG_FORMAT, "/* foo */ fun foo() {}"))
  }

  override fun handleRequest(event: APIGatewayProxyRequestEvent, context: Context?): String {
    return gson.toJson(
        try {
          val request = gson.fromJson(event.body, Request::class.java)
          val parsingErrors = ByteArrayOutputStream()
          val style = request.style
          val parsedArgs =
              parseOptions(
                  PrintStream(parsingErrors), if (style == null) arrayOf() else arrayOf(style))
          Response(
              format(
                  parsedArgs.formattingOptions.copy(maxWidth = request.maxWidth ?: 100),
                  request.source ?: ""),
              parsingErrors.toString().ifEmpty { null })
        } catch (e: Exception) {
          Response(null, e.message)
        })
  }

  companion object {
    val gson = Gson()
  }
}

class Request {
  var source: String? = ""
  var style: String? = ""
  var maxWidth: Int? = 100
}

data class Response(val source: String?, val err: String?)