import java.nio.charset.Charset
import java.util.function.Function

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

// This adds javacc generation support.

configure(rootProject) {
  configurations {
    javacc
  }

  dependencies {
    javacc libs.javacc.javacc
  }

  task javacc() {
    description "Regenerate sources for corresponding javacc grammar files."
    group "generation"

    dependsOn allprojects.collect { prj -> prj.tasks.withType(JavaCCTask) }
  }
}

def commonCleanups = { FileTree generatedFiles ->
  // This is a minor typo in a comment that nonetheless people have hand-corrected in the past.
  generatedFiles.matching({ include "CharStream.java" }).each {file ->
    modifyFile(file, { text ->
      return text.replace(
          "implemetation",
          "implementation");
    })
  }

  generatedFiles.each {file ->
    modifyFile(file, { text ->
      // Normalize EOLs and tabs (EOLs are a side-effect of modifyFile).
      text = text.replace("\t", "    ");
      text = text.replaceAll("JavaCC - OriginalChecksum=[^*]+", "(filtered)")
      text = text.replace("StringBuffer", "StringBuilder")
      return text
    })
  }

  generatedFiles.matching({ include "*TokenManager.java" }).each { file ->
    modifyFile(file, { text ->
      // Remove redundant imports.
      text = text.replaceAll(
          /(?m)^import .+/,
          "")
      // Add CharStream imports.
      text = text.replaceAll(
          /package (.+)/,
'''package $1
import javax.annotation.processing.Generated;
import org.apache.lucene.queryparser.charstream.CharStream;'''.trim())
      text = text.replace(
              "/** Token Manager. */",
'''/** Token Manager. */
@Generated("JavaCC")'''
      )
      // Eliminates redundant cast message.
      text = text.replace(
          "int hiByte = (int)(curChar >> 8);",
          "int hiByte = curChar >> 8;")
      // Access to forbidden APIs.
      text = text.replace(
          "public  java.io.PrintStream debugStream = System.out;",
          "// (debugStream omitted).")
      text = text.replace(
          "public  void setDebugStream(java.io.PrintStream ds) { debugStream = ds; }",
          "// (setDebugStream omitted).")
      return text
    })
  }
}

configure(project(":solr:core")) {
  task javacc(type: JavaCCTask) {
    description "Regenerate Solr query parser"
    group "generation"

    javaccFile = file('src/java/org/apache/solr/parser/QueryParser.jj')

    afterGenerate << commonCleanups
    afterGenerate << { FileTree generatedFiles ->
      generatedFiles.matching { include "QueryParser.java" }.each { file ->
        modifyFile(file, { text ->
          text = text.replace(
              "public QueryParser(CharStream ",
              "protected QueryParser(CharStream ")
          text = text.replace(
              "public QueryParser(QueryParserTokenManager ",
              "protected QueryParser(QueryParserTokenManager ")
          text = text.replace(
              "final private LookaheadSuccess jj_ls =",
              "static final private LookaheadSuccess jj_ls =")
          return text
        })
      }
    }
  }
}

// We always regenerate, no need to declare outputs.
class JavaCCTask extends DefaultTask {
  @InputFile
  File javaccFile

  /**
   * Apply closures to all generated files before they're copied back
   * to mainline code.
   */
  // A subtle bug here is that this makes it not an input... should be a list of replacements instead?
  @Internal
  List<Closure<FileTree>> afterGenerate = new ArrayList<>()

  @OutputFiles
  List<File> getGeneratedSources() {
    // Return the list of generated files.
    def baseDir = javaccFile.parentFile
    def baseName = javaccFile.name.replace(".jj", "")

    return [
        project.file("${baseDir}/${baseName}.java"),
        project.file("${baseDir}/${baseName}Constants.java"),
        project.file("${baseDir}/${baseName}TokenManager.java"),
        project.file("${baseDir}/ParseException.java"),
        project.file("${baseDir}/Token.java"),
        project.file("${baseDir}/TokenMgrError.java")
    ]
  }

  JavaCCTask() {
    dependsOn(project.rootProject.configurations.javacc)
  }

  @TaskAction
  def generate() {
    if (!javaccFile || !javaccFile.exists()) {
      throw new GradleException("Input file does not exist: ${javaccFile}")
    }

    // Run javacc generation into temporary folder so that we know all the generated files
    // and can post-process them easily.
    def tempDir = this.getTemporaryDir()
    tempDir.mkdirs()
    project.delete project.fileTree(tempDir, { include: "**/*.java" })

    def targetDir = javaccFile.parentFile
    logger.lifecycle("Recompiling JavaCC: ${project.rootDir.relativePath(javaccFile)}")

    def output = new ByteArrayOutputStream()
    def result = project.javaexec {
      classpath {
        project.rootProject.configurations.javacc
      }

      ignoreExitValue = true
      standardOutput = output
      errorOutput = output

      main = "org.javacc.parser.Main"
      args += [
          "-OUTPUT_DIRECTORY=${tempDir}",
          javaccFile
      ]
    }

    // Unless we request verbose logging, don't emit javacc output.
    if (result.exitValue != 0) {
      throw new GradleException("JavaCC failed to compile ${javaccFile}, here is the compilation output:\n${output}")
    }

    // Make sure we don't have warnings.
    if (output.toString(Charset.defaultCharset()).contains("Warning:")) {
      throw new GradleException("JavaCC emitted warnings for ${javaccFile}, here is the compilation output:\n${output}")
    }

    // Apply any custom modifications.
    def generatedFiles = project.fileTree(tempDir)

    afterGenerate.each {closure ->
      closure.call(generatedFiles)
    }

    // Copy back to mainline sources.
    project.copy {
      from tempDir
      into targetDir

      // We don't need CharStream interface as we redirect to our own.
      exclude "CharStream.java"
    }
  }
}
