// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
package com.intellij.codeInsight;

import com.intellij.openapi.project.Project;
import com.intellij.psi.*;
import com.intellij.psi.codeStyle.CodeStyleManager;
import com.intellij.psi.util.PsiUtil;
import com.intellij.util.SmartList;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.List;

public class BlockUtils {

  /**
   * Adds new statements before given anchor statement creating a new code block, if necessary
   *
   * @param anchor  existing statement
   * @param newStatements  the new statements which should be added before the existing one
   * @return last added physical statement
   */
  public static PsiStatement addBefore(PsiStatement anchor, PsiStatement... newStatements) {
    if (newStatements.length == 0) throw new IllegalArgumentException();
    PsiStatement oldStatement = anchor;
    PsiElement parent = oldStatement.getParent();
    while (parent instanceof PsiLabeledStatement) {
      oldStatement = (PsiStatement)parent;
      parent = oldStatement.getParent();
    }
    if (newStatements.length == 1 && oldStatement instanceof PsiEmptyStatement) {
      return (PsiStatement)oldStatement.replace(newStatements[0]);
    }
    if (!(parent instanceof PsiCodeBlock)) {
      oldStatement = expandSingleStatementToBlockStatement(oldStatement);
      parent = oldStatement.getParent();
    }
    PsiElement result = null;
    for (PsiStatement statement : newStatements) {
      result = parent.addBefore(statement, oldStatement);
    }
    return (PsiStatement)result;
  }

  /**
   * Add new statement after given anchor statement creating code block, if necessary
   *
   * @param anchor existing statement
   * @param newStatement a new statement which should be added after an existing one
   * @return added physical statement
   */
  public static PsiStatement addAfter(PsiStatement anchor, PsiStatement newStatement) {
    PsiStatement oldStatement = anchor;
    PsiElement parent = oldStatement.getParent();
    while (parent instanceof PsiLabeledStatement) {
      oldStatement = (PsiStatement)parent;
      parent = oldStatement.getParent();
    }
    if (!(parent instanceof PsiCodeBlock)) {
      oldStatement = expandSingleStatementToBlockStatement(oldStatement);
      parent = oldStatement.getParent();
    }
    return (PsiStatement)parent.addAfter(newStatement, oldStatement);
  }

  /**
   * Replaces a statement with a block statement with the statement inside it. As usual the block statement contains a code block, which
   * will contain the specified statement.
   *
   * @param statement  the statement to replace
   * @return a new statement equivalent to the argument, but inside a block
   */
  public static <T extends PsiStatement> T expandSingleStatementToBlockStatement(@NotNull T statement) {
    if (statement instanceof PsiBlockStatement) {
      return statement;
    }
    final PsiBlockStatement blockStatement = (PsiBlockStatement)
      JavaPsiFacade.getElementFactory(statement.getProject()).createStatementFromText("{\n}", statement);
    blockStatement.getCodeBlock().add(statement);
    final PsiBlockStatement result = (PsiBlockStatement)statement.replace(blockStatement);

    final PsiElement sibling = result.getNextSibling();
    if (sibling instanceof PsiWhiteSpace && PsiUtil.isJavaToken(sibling.getNextSibling(), JavaTokenType.ELSE_KEYWORD)) {
      sibling.delete();
    }
    //noinspection unchecked
    return (T)result.getCodeBlock().getStatements()[0];
  }

  @Nullable
  public static PsiElement getBody(PsiElement element) {
    if (element instanceof PsiLoopStatement) {
      final PsiStatement loopBody = ((PsiLoopStatement)element).getBody();
      return loopBody instanceof PsiBlockStatement ? ((PsiBlockStatement)loopBody).getCodeBlock() : loopBody;
    }
    else if (element instanceof PsiParameterListOwner) {
      return ((PsiParameterListOwner)element).getBody();
    }
    else if (element instanceof PsiSynchronizedStatement) {
      return ((PsiSynchronizedStatement)element).getBody();
    }
    else if (element instanceof PsiSwitchStatement) {
      return ((PsiSwitchStatement)element).getBody();
    }
    else if (element instanceof PsiClassInitializer) {
      return ((PsiClassInitializer)element).getBody();
    }
    else if (element instanceof PsiCatchSection) {
      return ((PsiCatchSection)element).getCatchBlock();
    }
    throw new AssertionError("can't get body from " + element);
  }

  public static void unwrapTryBlock(PsiTryStatement tryStatement) {
    PsiCodeBlock tryBlock = tryStatement.getTryBlock();
    if (tryBlock == null) {
      return;
    }
    final PsiElement parent = tryStatement.getParent();
    boolean singleStatement = false;
    if (parent instanceof PsiStatement) {
      final PsiStatement[] statements = tryBlock.getStatements();
      if (statements.length == 1 && !(statements[0] instanceof PsiDeclarationStatement)) {
        singleStatement = true;
      }
      else {
        tryStatement = expandSingleStatementToBlockStatement(tryStatement);
      }
    }
    else if (parent instanceof PsiCodeBlock) {
      if (containsConflictingDeclarations(tryBlock, (PsiCodeBlock)parent)) {
        tryStatement = expandSingleStatementToBlockStatement(tryStatement);
      }
    }
    else {
      return;
    }

    tryBlock = tryStatement.getTryBlock();
    assert tryBlock != null;
    final PsiElement first = singleStatement ? skip(tryBlock.getFirstBodyElement(), true) : tryBlock.getFirstBodyElement();
    final PsiElement last = singleStatement? skip(tryBlock.getLastBodyElement(), false) : tryBlock.getLastBodyElement();
    assert first != null && last != null;
    tryStatement.getParent().addRangeBefore(first, last, tryStatement);
    tryStatement.delete();
  }

  private static PsiElement skip(PsiElement element, boolean forward) {
    if (!(element instanceof PsiWhiteSpace)) {
      return element;
    }
    return forward ? element.getNextSibling() : element.getPrevSibling();
  }

  public static boolean containsConflictingDeclarations(PsiCodeBlock block, PsiCodeBlock parentBlock) {
    final PsiStatement[] statements = block.getStatements();
    if (statements.length == 0) {
      return false;
    }
    final int endOffset = block.getTextRange().getEndOffset();
    final List<PsiCodeBlock> affectedBlocks =
      SyntaxTraverser.psiTraverser(parentBlock)
        .filter(PsiCodeBlock.class)
        .filter(cb -> cb.getTextRange().getEndOffset() > endOffset)
        .addAllTo(new SmartList<>());
    final Project project = block.getProject();
    final JavaPsiFacade facade = JavaPsiFacade.getInstance(project);
    final PsiResolveHelper resolveHelper = facade.getResolveHelper();
    for (final PsiStatement statement : statements) {
      if (!(statement instanceof PsiDeclarationStatement)) {
        continue;
      }
      final PsiDeclarationStatement declaration = (PsiDeclarationStatement)statement;
      final PsiElement[] variables = declaration.getDeclaredElements();
      for (PsiElement variable : variables) {
        if (!(variable instanceof PsiLocalVariable)) {
          continue;
        }
        final PsiLocalVariable localVariable = (PsiLocalVariable)variable;
        final String variableName = localVariable.getName();
        if (variableName == null) {
          continue;
        }
        for (PsiCodeBlock codeBlock : affectedBlocks) {
          final PsiVariable target = resolveHelper.resolveAccessibleReferencedVariable(variableName, codeBlock);
          if (target instanceof PsiLocalVariable) {
            return true;
          }
          if (target instanceof PsiField) {
            for (PsiCodeBlock affectedBlock : affectedBlocks) {
              if (!SyntaxTraverser.psiTraverser(affectedBlock).filter(PsiReferenceExpression.class).filter(ref -> ref.resolve() == target).isEmpty()) {
                return true;
              }
            }
          }
        }
      }
    }
    return false;
  }

  public static void inlineCodeBlock(@NotNull PsiStatement orig, PsiCodeBlock codeBlock) {
    PsiJavaToken lBrace = codeBlock.getLBrace();
    PsiJavaToken rBrace = codeBlock.getRBrace();
    if (lBrace == null || rBrace == null) return;

    final PsiElement[] children = codeBlock.getChildren();
    if (children.length > 2) {
      final PsiElement added =
        orig.getParent().addRangeBefore(
          children[1],
          children[children.length - 2],
          orig);
      final CodeStyleManager codeStyleManager = CodeStyleManager.getInstance(orig.getManager());
      codeStyleManager.reformat(added);
    }
    orig.delete();
  }

  public static PsiBlockStatement createBlockStatement(Project project) {
    return (PsiBlockStatement)JavaPsiFacade.getElementFactory(project).createStatementFromText("{}", null);
  }
}