/*
 * Copyright 2000-2013 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.imports;

import com.intellij.codeInsight.hint.QuestionAction;
import com.intellij.ide.DataManager;
import com.intellij.lang.injection.InjectedLanguageManager;
import com.intellij.openapi.actionSystem.DataContext;
import com.intellij.openapi.application.Result;
import com.intellij.openapi.command.WriteCommandAction;
import com.intellij.openapi.editor.colors.EditorColorsManager;
import com.intellij.openapi.editor.colors.EditorColorsScheme;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.roots.ProjectFileIndex;
import com.intellij.openapi.ui.popup.PopupChooserBuilder;
import com.intellij.openapi.util.Comparing;
import com.intellij.openapi.vfs.VirtualFile;
import com.intellij.psi.*;
import com.intellij.ui.SimpleColoredComponent;
import com.intellij.ui.SimpleTextAttributes;
import com.intellij.ui.components.JBList;
import com.intellij.util.Consumer;
import com.intellij.util.Function;
import com.jetbrains.python.PyBundle;
import com.jetbrains.python.psi.*;
import org.jetbrains.annotations.NotNull;

import javax.swing.*;
import java.awt.*;
import java.util.List;

/**
 * Turns an unqualified unresolved identifier into qualified and resolvable.
 *
 * @author dcheryasov
 */
public class ImportFromExistingAction implements QuestionAction {
  PyElement myTarget;
  List<ImportCandidateHolder> mySources; // list of <import, imported_item>
  String myName;
  boolean myUseQualifiedImport;
  private Runnable myOnDoneCallback;
  private final boolean myImportLocally;

  /**
   * @param target element to become qualified as imported.
   * @param sources clauses of import to be used.
   * @param name relevant name ot the target element (e.g. of identifier in an expression).
   * @param useQualified if True, use qualified "import modulename" instead of "from modulename import ...".
   */
  public ImportFromExistingAction(@NotNull PyElement target, @NotNull List<ImportCandidateHolder> sources, @NotNull String name,
                                  boolean useQualified, boolean importLocally) {
    myTarget = target;
    mySources = sources;
    myName = name;
    myUseQualifiedImport = useQualified;
    myImportLocally = importLocally;
  }

  public void onDone(Runnable callback) {
    assert myOnDoneCallback == null;
    myOnDoneCallback = callback;
  }


  /**
   * Alters either target (by qualifying a name) or source (by explicitly importing the name).
   * @return true if action succeeded
   */
  public boolean execute() {
    // check if the tree is sane
    PsiDocumentManager.getInstance(myTarget.getProject()).commitAllDocuments();
    if (!myTarget.isValid()) return false;
    if ((myTarget instanceof PyQualifiedExpression) && ((((PyQualifiedExpression)myTarget).isQualified()))) return false; // we cannot be qualified
    for (ImportCandidateHolder item : mySources) {
      if (!item.getImportable().isValid()) return false;
      if (!item.getFile().isValid()) return false;
      if (item.getImportElement() != null && !item.getImportElement().isValid()) return false;
    }
    if (mySources.isEmpty()) {
      return false;
    }
    // act
    if (mySources.size() > 1) {
      selectSourceAndDo();
    }
    else doWriteAction(mySources.get(0));
    return true;
  }

  private void selectSourceAndDo() {
    // GUI part
    ImportCandidateHolder[] items = mySources.toArray(new ImportCandidateHolder[mySources.size()]); // silly JList can't handle modern collections
    final JList list = new JBList(items);
    list.setCellRenderer(new CellRenderer(myName));

    final Runnable runnable = new Runnable() {
      public void run() {
        int index = list.getSelectedIndex();
        if (index < 0) return;
        PsiDocumentManager.getInstance(myTarget.getProject()).commitAllDocuments();
        doWriteAction(mySources.get(index));
      }
    };

    DataManager.getInstance().getDataContextFromFocus().doWhenDone(new Consumer<DataContext>() {
      @Override
      public void consume(DataContext dataContext) {
        new PopupChooserBuilder(list)
          .setTitle(myUseQualifiedImport? PyBundle.message("ACT.qualify.with.module") : PyBundle.message("ACT.from.some.module.import"))
          .setItemChoosenCallback(runnable)
          .setFilteringEnabled(new Function<Object, String>() {
            @Override
            public String fun(Object o) {
              return ((ImportCandidateHolder) o).getPresentableText(myName);
            }
          })
          .createPopup()
          .showInBestPositionFor(dataContext);
      }
    });
  }

  private void doIt(final ImportCandidateHolder item) {
    PyImportElement src = item.getImportElement();
    if (src != null) {
      addToExistingImport(src);
    }
    else { // no existing import, add it then use it
      addImportStatement(item);
    }
  }

  private void addImportStatement(ImportCandidateHolder item) {
    final Project project = myTarget.getProject();
    final PyElementGenerator gen = PyElementGenerator.getInstance(project);
    AddImportHelper.ImportPriority priority = AddImportHelper.getImportPriority(myTarget, item.getFile());
    PsiFile file = myTarget.getContainingFile();
    InjectedLanguageManager manager = InjectedLanguageManager.getInstance(project);
    if (manager.isInjectedFragment(file)) {
      file = manager.getTopLevelFile(myTarget);
    }
    // We are trying to import top-level module or package which thus cannot be qualified
    if (isRoot(item.getFile())) {
      if (myImportLocally) {
        AddImportHelper.addLocalImportStatement(myTarget, myName);
      } else {
        AddImportHelper.addImportStatement(file, myName, null, priority);
      }
    }
    else {
      final String qualifiedName = item.getPath().toString();
      if (myUseQualifiedImport) {
        String nameToImport = qualifiedName;
        if (item.getImportable() instanceof PsiFileSystemItem) {
          nameToImport += "." + myName;
        }
        if (myImportLocally) {
          AddImportHelper.addLocalImportStatement(myTarget, nameToImport);
        }
        else {
          AddImportHelper.addImportStatement(file, nameToImport, null, priority);
        }
        myTarget.replace(gen.createExpressionFromText(LanguageLevel.forElement(myTarget), qualifiedName + "." + myName));
      }
      else {
        if (myImportLocally) {
          AddImportHelper.addLocalFromImportStatement(myTarget, qualifiedName, myName);
        }
        else {
          AddImportHelper.addImportFromStatement(file, qualifiedName, myName, null, priority);
        }
      }
    }
  }


  private void addToExistingImport(PyImportElement src) {
    final PyElementGenerator gen = PyElementGenerator.getInstance(myTarget.getProject());
    // did user choose 'import' or 'from import'?
    PsiElement parent = src.getParent();
    if (parent instanceof PyFromImportStatement) {
      // add another import element right after the one we got
      PsiElement newImportElement = gen.createImportElement(LanguageLevel.getDefault(), myName);
      parent.add(newImportElement);
    }
    else { // just 'import'
      // all we need is to qualify our target
      myTarget.replace(gen.createExpressionFromText(LanguageLevel.forElement(myTarget), src.getVisibleName() + "." + myName));
    }
  }

  private void doWriteAction(final ImportCandidateHolder item) {
    PsiElement src = item.getImportable();
    new WriteCommandAction(src.getProject(), PyBundle.message("ACT.CMD.use.import"), myTarget.getContainingFile()) {
      @Override
      protected void run(Result result) throws Throwable {
        doIt(item);
      }
    }.execute();
    if (myOnDoneCallback != null) {
      myOnDoneCallback.run();
    }
  }

  public static boolean isRoot(PsiFileSystemItem directory) {
    if (directory == null) return true;
    VirtualFile vFile = directory.getVirtualFile();
    if (vFile == null) return true;
    ProjectFileIndex fileIndex = ProjectFileIndex.SERVICE.getInstance(directory.getProject());
    return Comparing.equal(fileIndex.getClassRootForFile(vFile), vFile) ||
           Comparing.equal(fileIndex.getContentRootForFile(vFile), vFile) ||
           Comparing.equal(fileIndex.getSourceRootForFile(vFile), vFile);
  }

  public static boolean isResolved(PsiReference reference) {
    if (reference instanceof PsiPolyVariantReference) {
      return ((PsiPolyVariantReference)reference).multiResolve(false).length > 0;
    }
    return reference.resolve() != null;
  }

  // Stolen from FQNameCellRenderer
  private static class CellRenderer extends SimpleColoredComponent implements ListCellRenderer {
    private final Font FONT;
    private final String myName;

    public CellRenderer(String name) {
      myName = name;
      EditorColorsScheme scheme = EditorColorsManager.getInstance().getGlobalScheme();
      FONT = new Font(scheme.getEditorFontName(), Font.PLAIN, scheme.getEditorFontSize());
      setOpaque(true);
    }

    // value is a QualifiedHolder
    public Component getListCellRendererComponent(
      JList list,
      Object value, // expected to be
      int index,
      boolean isSelected,
      boolean cellHasFocus
    ){

      clear();

      ImportCandidateHolder item = (ImportCandidateHolder)value;
      setIcon(item.getImportable().getIcon(0));
      String item_name = item.getPresentableText(myName);
      append(item_name, SimpleTextAttributes.REGULAR_ATTRIBUTES);

      setFont(FONT);
      if (isSelected) {
        setBackground(list.getSelectionBackground());
        setForeground(list.getSelectionForeground());
      }
      else {
        setBackground(list.getBackground());
        setForeground(list.getForeground());
      }
      return this;
    }
  }
}