// Copyright (c) 2022, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
package com.android.tools.r8.keepanno.keeprules;

import com.android.tools.r8.keepanno.ast.KeepConsequences;
import com.android.tools.r8.keepanno.ast.KeepEdge;
import com.android.tools.r8.keepanno.ast.KeepItemPattern;
import com.android.tools.r8.keepanno.ast.KeepMemberPattern;
import com.android.tools.r8.keepanno.ast.KeepMethodAccessPattern;
import com.android.tools.r8.keepanno.ast.KeepMethodNamePattern;
import com.android.tools.r8.keepanno.ast.KeepMethodParametersPattern;
import com.android.tools.r8.keepanno.ast.KeepMethodPattern;
import com.android.tools.r8.keepanno.ast.KeepMethodReturnTypePattern;
import com.android.tools.r8.keepanno.ast.KeepOptions;
import com.android.tools.r8.keepanno.ast.KeepOptions.KeepOption;
import com.android.tools.r8.keepanno.ast.KeepPackagePattern;
import com.android.tools.r8.keepanno.ast.KeepPreconditions;
import com.android.tools.r8.keepanno.ast.KeepQualifiedClassNamePattern;
import com.android.tools.r8.keepanno.ast.KeepTarget;
import com.android.tools.r8.keepanno.ast.KeepTypePattern;
import com.android.tools.r8.keepanno.ast.KeepUnqualfiedClassNamePattern;
import com.android.tools.r8.keepanno.utils.Unimplemented;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;
import java.util.stream.Collectors;

public class KeepRuleExtractor {

  private final Consumer<String> ruleConsumer;

  public KeepRuleExtractor(Consumer<String> ruleConsumer) {
    this.ruleConsumer = ruleConsumer;
  }

  public void extract(KeepEdge edge) {
    List<ItemRule> consequentRules = getConsequentRules(edge.getConsequences());
    printConditionalRules(consequentRules, edge.getPreconditions());
  }

  private List<ItemRule> getConsequentRules(KeepConsequences consequences) {
    List<ItemRule> consequentItems = new ArrayList<>();
    consequences.forEachTarget(target -> consequentItems.add(new ItemRule(target)));
    return consequentItems;
  }

  private void printConditionalRules(
      List<ItemRule> consequentRules, KeepPreconditions preconditions) {
    boolean[] hasAtLeastOneConditionalClause = new boolean[1];
    preconditions.forEach(
        condition -> {
          KeepItemPattern conditionItem = condition.getItemPattern();
          // If the conditions is "any" then we ignore it for now (identity of conjunction).
          if (conditionItem.isAny()) {
            return;
          }
          hasAtLeastOneConditionalClause[0] = true;
          consequentRules.forEach(
              consequentItem -> {
                // Since conjunctions are not supported in keep rules, we expand them into
                // disjunctions so conservatively we keep the consequences if any one of
                // the preconditions hold.
                StringBuilder builder = new StringBuilder();
                if (!consequentItem.isMemberOnlyConsequent()
                    || !conditionItem
                        .getClassNamePattern()
                        .equals(consequentItem.getHolderPattern())) {
                  builder.append("-if ");
                  printItem(builder, conditionItem);
                  builder.append(' ');
                }
                printConsequentRule(builder, consequentItem);
                ruleConsumer.accept(builder.toString());
              });
        });
    assert !(preconditions.isAlways() && hasAtLeastOneConditionalClause[0]);
    if (!hasAtLeastOneConditionalClause[0]) {
      // If there are no preconditions, print each consequent as is.
      consequentRules.forEach(
          r -> ruleConsumer.accept(printConsequentRule(new StringBuilder(), r).toString()));
    }
  }

  private static StringBuilder printConsequentRule(StringBuilder builder, ItemRule rule) {
    if (rule.isMemberOnlyConsequent()) {
      builder.append("-keepclassmembers");
    } else {
      builder.append("-keep");
    }
    for (KeepOption option : KeepOption.values()) {
      if (rule.options.isAllowed(option)) {
        builder.append(",allow").append(getOptionString(option));
      }
    }
    return builder.append(" ").append(rule.getKeepRuleForItem());
  }

  private static StringBuilder printItem(StringBuilder builder, KeepItemPattern clazzPattern) {
    builder.append("class ");
    printClassName(builder, clazzPattern.getClassNamePattern());
    if (!clazzPattern.getExtendsPattern().isAny()) {
      throw new Unimplemented();
    }
    KeepMemberPattern member = clazzPattern.getMemberPattern();
    if (member.isNone()) {
      return builder;
    }
    if (member.isAll()) {
      return builder.append(" { *; }");
    }
    if (member.isMethod()) {
      builder.append(" {");
      printMethod(builder.append(' '), member.asMethod());
      return builder.append(" }");
    }
    throw new Unimplemented();
  }

  private static StringBuilder printMethod(StringBuilder builder, KeepMethodPattern methodPattern) {
    if (methodPattern.isAnyMethod()) {
      return builder.append("<methods>;");
    }
    printAccess(builder, " ", methodPattern.getAccessPattern());
    printReturnType(builder, methodPattern.getReturnTypePattern());
    builder.append(' ');
    printMethodName(builder, methodPattern.getNamePattern());
    printParameters(builder, methodPattern.getParametersPattern());
    return builder.append(';');
  }

  private static StringBuilder printParameters(
      StringBuilder builder, KeepMethodParametersPattern parametersPattern) {
    if (parametersPattern.isAny()) {
      return builder.append("(...)");
    }
    return builder
        .append('(')
        .append(
            parametersPattern.asList().stream()
                .map(Object::toString)
                .collect(Collectors.joining(", ")))
        .append(')');
  }

  private static StringBuilder printMethodName(
      StringBuilder builder, KeepMethodNamePattern namePattern) {
    return namePattern.isAny()
        ? builder.append("*")
        : builder.append(namePattern.asExact().getName());
  }

  private static StringBuilder printReturnType(
      StringBuilder builder, KeepMethodReturnTypePattern returnTypePattern) {
    if (returnTypePattern.isVoid()) {
      return builder.append("void");
    }
    return printType(builder, returnTypePattern.asType());
  }

  private static StringBuilder printType(StringBuilder builder, KeepTypePattern typePattern) {
    if (typePattern.isAny()) {
      return builder.append("***");
    }
    throw new Unimplemented();
  }

  private static StringBuilder printAccess(
      StringBuilder builder, String indent, KeepMethodAccessPattern accessPattern) {
    if (accessPattern.isAny()) {
      // No text will match any access pattern.
      // Don't print the indent in this case.
      return builder;
    }
    throw new Unimplemented();
  }

  private static StringBuilder printClassName(
      StringBuilder builder, KeepQualifiedClassNamePattern classNamePattern) {
    if (classNamePattern.isAny()) {
      return builder.append('*');
    }
    printPackagePrefix(builder, classNamePattern.getPackagePattern());
    return printSimpleClassName(builder, classNamePattern.getNamePattern());
  }

  private static StringBuilder printPackagePrefix(
      StringBuilder builder, KeepPackagePattern packagePattern) {
    if (packagePattern.isAny()) {
      return builder.append("**.");
    }
    if (packagePattern.isTop()) {
      return builder;
    }
    assert packagePattern.isExact();
    return builder.append(packagePattern.getExactPackageAsString()).append('.');
  }

  private static StringBuilder printSimpleClassName(
      StringBuilder builder, KeepUnqualfiedClassNamePattern namePattern) {
    if (namePattern.isAny()) {
      return builder.append('*');
    }
    assert namePattern.isExact();
    return builder.append(namePattern.asExact().getExactNameAsString());
  }

  private static String getOptionString(KeepOption option) {
    switch (option) {
      case SHRINKING:
        return "shrinking";
      case OPTIMIZING:
        return "optimization";
      case OBFUSCATING:
        return "obfuscation";
      case ACCESS_MODIFYING:
        return "accessmodification";
      default:
        throw new Unimplemented();
    }
  }

  private static class ItemRule {
    private final KeepTarget target;
    private final KeepOptions options;
    private String ruleLine = null;

    public ItemRule(KeepTarget target) {
      this.target = target;
      this.options = target.getOptions();
    }

    public boolean isMemberOnlyConsequent() {
      KeepItemPattern item = target.getItem();
      return !item.isAny() && !item.getMemberPattern().isNone();
    }

    public KeepQualifiedClassNamePattern getHolderPattern() {
      return target.getItem().getClassNamePattern();
    }

    public String getKeepRuleForItem() {
      if (ruleLine == null) {
        KeepItemPattern item = target.getItem();
        ruleLine =
            item.isAny() ? "class * { *; }" : printItem(new StringBuilder(), item).toString();
      }
      return ruleLine;
    }
  }
}