/*
 * Copyright 2000-2014 JetBrains s.r.o.
 *
 * 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.jetbrains.python.codeInsight.controlflow;

import com.intellij.openapi.util.Key;
import com.jetbrains.python.PyLanguageFacadeKt;
import com.jetbrains.python.codeInsight.dataflow.scope.Scope;
import com.jetbrains.python.codeInsight.dataflow.scope.impl.ScopeImpl;
import com.jetbrains.python.psi.LanguageLevel;
import com.jetbrains.python.psi.PyUtil;
import org.jetbrains.annotations.NotNull;

import java.lang.ref.SoftReference;

import static com.intellij.reference.SoftReference.dereference;


public final class ControlFlowCache {
  private static final Key<SoftReference<PyControlFlow>> CONTROL_FLOW_KEY =
    Key.create("com.jetbrains.python.codeInsight.controlflow.ControlFlow");
  private static final Key<SoftReference<Scope>> SCOPE_KEY = Key.create("com.jetbrains.python.codeInsight.controlflow.Scope");

  private ControlFlowCache() {
  }

  public static void clear(ScopeOwner scopeOwner) {
    scopeOwner.putUserData(CONTROL_FLOW_KEY, null);
    scopeOwner.putUserData(SCOPE_KEY, null);
  }

  public static @NotNull PyControlFlow getControlFlow(@NotNull ScopeOwner element,
                                                      @NotNull PyControlFlowBuilder controlFlowBuilder) {
    SoftReference<PyControlFlow> ref = element.getUserData(CONTROL_FLOW_KEY);
    PyControlFlow flow = dereference(ref);
    if (flow == null) {
      flow = controlFlowBuilder.buildControlFlow(element);
      element.putUserData(CONTROL_FLOW_KEY, new SoftReference<>(flow));
    }
    return flow;
  }

  public static @NotNull PyControlFlow getControlFlow(@NotNull ScopeOwner element) {
    LanguageLevel languageLevel = PyLanguageFacadeKt.getEffectiveLanguageLevel(element.getContainingFile());
    return getControlFlow(element, new PyControlFlowBuilder(languageLevel));
  }

  public static @NotNull Scope getScope(@NotNull ScopeOwner element) {
    SoftReference<Scope> ref = element.getUserData(SCOPE_KEY);
    Scope scope = dereference(ref);
    if (scope == null) {
      scope = new ScopeImpl(element);
      element.putUserData(SCOPE_KEY, new SoftReference<>(scope));
    }
    return scope;
  }

  public static @NotNull PyDataFlow getDataFlow(@NotNull ScopeOwner element, @NotNull FlowContext context) {
    // Cache will reset on psi modification, same as TypeEvalContext
    return PyUtil.getParameterizedCachedValue(element, context, ctx -> new PyDataFlow(getControlFlow(element), ctx));
  }
}
