src/resourceshrinker/java/com/android/build/shrinker/obfuscation/ObfuscatedClasses.kt

/*
 * Copyright (C) 2020 The Android Open Source Project
 *
 * 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.android.build.shrinker.obfuscation

import com.google.common.collect.ImmutableMap

/** Contains mappings between obfuscated classes and methods to original ones. */
public class ObfuscatedClasses private constructor(builder: Builder) {

  public companion object {
    @JvmField public val NO_OBFUSCATION: ObfuscatedClasses = Builder().build()
  }

  private val obfuscatedClasses = ImmutableMap.copyOf(builder.obfuscatedClasses)
  private val obfuscatedMethods = ImmutableMap.copyOf(builder.obfuscatedMethods)

  public fun resolveOriginalMethod(obfuscatedMethod: ClassAndMethod): ClassAndMethod {
    return obfuscatedMethods.getOrElse(obfuscatedMethod) {
      val realClassName =
        obfuscatedClasses[obfuscatedMethod.className] ?: obfuscatedMethod.className
      ClassAndMethod(realClassName, obfuscatedMethod.methodName)
    }
  }

  public fun resolveOriginalClass(obfuscatedClass: String): String {
    return obfuscatedClasses[obfuscatedClass] ?: obfuscatedClass
  }

  /**
   * Builder that allows to build obfuscated mappings in a way when next method mapping is added to
   * previous class mapping. Example: builder .addClassMapping(Pair(classA, obfuscatedClassA))
   * .addMethodMapping(Pair(classAMethod1, obfuscatedClassAMethod1))
   * .addMethodMapping(Pair(classAMethod2, obfuscatedClassAMethod2)) .addClassMapping(Pair(classB,
   * obfuscatedClassB)) .addMethodMapping(Pair(classBMethod1, obfuscatedClassBMethod1))
   */
  public class Builder {

    public val obfuscatedClasses: MutableMap<String, String> = mutableMapOf()
    public val obfuscatedMethods: MutableMap<ClassAndMethod, ClassAndMethod> = mutableMapOf()

    public var currentClassMapping: Pair<String, String>? = null

    /**
     * Adds class mapping: original class name -> obfuscated class name.
     *
     * @param mapping Pair(originalClassName, obfuscatedClassName)
     */
    public fun addClassMapping(mapping: Pair<String, String>): Builder {
      currentClassMapping = mapping
      obfuscatedClasses += Pair(mapping.second, mapping.first)
      return this
    }

    /**
     * Adds method mapping: original method name -> obfuscated method name to the latest added class
     * mapping.
     *
     * @param mapping Pair(originalMethodName, obfuscatedMethodName)
     */
    public fun addMethodMapping(mapping: Pair<String, String>): Builder {
      if (currentClassMapping != null) {
        obfuscatedMethods +=
          Pair(
            ClassAndMethod(currentClassMapping!!.second, mapping.second),
            ClassAndMethod(currentClassMapping!!.first, mapping.first),
          )
      }
      return this
    }

    public fun build(): ObfuscatedClasses = ObfuscatedClasses(this)
  }
}

public data class ClassAndMethod(val className: String, val methodName: String)