package bluej.stride.framedjava.errors;

import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.Set;

import bluej.compiler.Diagnostic.DiagnosticOrigin;
import bluej.stride.framedjava.ast.ASTUtility;
import bluej.stride.framedjava.ast.FilledExpressionSlotFragment;
import bluej.stride.framedjava.ast.NameDefSlotFragment;
import bluej.stride.framedjava.ast.StringSlotFragment;
import bluej.stride.framedjava.ast.TypeSlotFragment;
import bluej.stride.framedjava.errors.Correction.SimpleCorrectionInfo;
import bluej.stride.framedjava.frames.AssignFrame;
import bluej.stride.framedjava.frames.ClassFrame;
import bluej.stride.framedjava.frames.VarFrame;
import bluej.stride.generic.Frame;
import bluej.stride.generic.FrameCursor;
import threadchecker.OnThread;
import threadchecker.Tag;

public class UndeclaredVariableLvalueError
extends DirectSlotError{    
   private final AssignFrame assignFrame;
   
   private final List<Correction> corrections = new ArrayList<>();
   
   private final String varName;

   
   


| Creates an error about an undeclared variable being used on the left-hand side of an assignment.
| The variable will occupy the entire left-hand side of an assignment frame, and will thus be
| a candidate for a quick fix which turns the assignment into a declaration+initialisation of that variable.
|
| @param slotFragment The fragment with the error.
| @param assignFrame The assignment frame with the error.
| @param possibleCorrections The possible other variable names (unfiltered: all variable names which are in scope)
|
@OnThread(Tag.FXPlatform)
   
   public UndeclaredVariableLvalueError(StringSlotFragment slotFragment, AssignFrame assignFrame, Set<String> possibleCorrections)
   {
      super(slotFragment, DiagnosticOrigin.STRIDE_LATE);
       
      this.assignFrame = assignFrame;
      this.corrections.addAll(Correction.winnowAndCreateCorrections(assignFrame.getLHS().getText(), possibleCorrections.stream().map(SimpleCorrectionInfo::new), s -> assignFrame.getLHS().setText(s)));
      this.varName = assignFrame.getLHS().getText();     
      }
    
    
   
   @Override
   @OnThread(Tag.Any)
   
   public String getMessage()
   {        
      return "Undeclared variable: " + varName;     
      }

   
   @Override
   
   public List getFixSuggestions()
   {        
      ArrayList<FixSuggestion> fixes = new ArrayList<>();
        
       
      fixes.add(new ChangeAssignmentToDeclarationAndInitialisation());
       
      fixes.add(new AddFieldDeclaration());
      fixes.addAll(corrections);
        
       
      return fixes;     
      }
    
   
   private class ChangeAssignmentToDeclarationAndInitialisation
extends FixSuggestion
   {        
      @Override
       
      public String getDescription()
       {            
         return "Declare variable here";         
         }

       
      @Override
       
      public void execute()
       {            
         
         assignFrame.getParentCanvas().replaceBlock(assignFrame, new VarFrame(assignFrame.getEditor(), null, false, false, new TypeSlotFragment("", ""), 
                       
         new NameDefSlotFragment(assignFrame.getLHS().getText()), new FilledExpressionSlotFragment(assignFrame.getRHS().getSlotElement()), true));         
         }     
      }
    
   
   private class AddFieldDeclaration
extends FixSuggestion
   {         
      @Override
       
      public String getDescription()
       {            
         return "Declare field in class";         
         }

       
      @Override
       
      public void execute()
       {            
         
         ClassFrame classFrame = (ClassFrame)ASTUtility.getTopLevelElement(assignFrame.getCode()).getFrame();
            
         List<Frame> members = classFrame.getfieldsCanvas().getBlockContents();
            
         Optional<Frame> firstNonField = members.stream().filter(f -> !(f instanceof VarFrame)).findFirst();
            
         FrameCursor cursorAfter = (firstNonField.isPresent()) ? cursorAfter = classFrame.getfieldsCanvas().getCursorBefore(firstNonField.get()) : classFrame.getfieldsCanvas().getLastCursor();
           
         classFrame.getfieldsCanvas().insertBlockBefore(new VarFrame(assignFrame.getEditor(), null, false, false, 
                   
         new TypeSlotFragment("", ""), new NameDefSlotFragment(assignFrame.getLHS().getText()), null, true), cursorAfter);         
         }     
      }

   
   @Override
   
   public boolean isJavaPos()
   {        
      return false;     
      } 
   }