package app.controllers;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.net.URL;
import java.util.Collection;
import java.util.ResourceBundle;
import java.util.Scanner;

import com.google.common.eventbus.EventBus;
import com.google.common.eventbus.Subscribe;

import org.fxmisc.richtext.CodeArea;
import org.fxmisc.richtext.LineNumberFactory;
import org.fxmisc.richtext.model.StyleSpans;
import org.fxmisc.richtext.model.TwoDimensional.Bias;
import org.fxmisc.richtext.model.TwoDimensional.Position;

import app.events.CopyEvent;
import app.events.CutEvent;
import app.events.EditorChangedEvent;
import app.events.LanguageChangedEvent;
import app.events.PasteEvent;
import app.events.RedoEvent;
import app.events.SaveFile;
import app.events.ToggleCommentEvent;
import app.events.ToggleWrapTextEvent;
import app.events.UndoEvent;
import app.events.FileSaveStateChangedEvent;
import app.events.FileSelectedEvent;
import app.model.Model;
import app.service.LanguageOperations;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Alert;
import javafx.scene.control.Alert.AlertType;

/**
 * A FXML controller that controls the editor component of the UI
 */
public class EditorController implements Initializable, Controller {

  @FXML
  private CodeArea editor;

  private EventBus eventBus;

  /**
   * Initializes the controller, and binds the event of change in editor content
   * to {@link #editorChanged() editorChanged}
   */
  @Override
  public void initialize(URL url, ResourceBundle resourceBundle) {
    editor.setParagraphGraphicFactory(LineNumberFactory.get(editor));

    editor.textProperty().addListener((obs, oldV, newV) -> this.editorChanged());
  }

  @Override
  public void setEventBus(EventBus eventBus) {
    this.eventBus = eventBus;
    this.eventBus.register(this);
  }

  /**
   * Applies highlighting to the editor.
   * 
   * @param highlighting highlighting data
   */
  private void setHighlighting(StyleSpans<Collection<String>> highlighting) {
    this.editor.setStyleSpans(0, highlighting);
  }

  /**
   * Recalculates and refreshes the syntax highlighting of the editor.
   */
  private void refreshHighlighting() {
    this.setHighlighting(LanguageOperations.syntaxHighlight(this.editor.getText(), Model.getLanguage()));
  }

  /**
   * Uses the {@link app.model.ProgrammingLanguage ProgrammingLanguage} in
   * {@link app.model.Model Model} to determine whether the current line/selection
   * is commented or not, and toggles the comment.
   * 
   * @see app.model.ProgrammingLanguage#commentLine(String)
   *      ProgrammingLanguage.commentLine(line)
   */
  private void toggleComment() {
    if (editor.getSelectedText().equals("")) {
      String currentLine = editor.getText(editor.getCurrentParagraph());

      String newText;
      if (Model.getLanguage().isCommentedLine(currentLine))
        newText = Model.getLanguage().unCommentLine(currentLine);
      else
        newText = Model.getLanguage().commentLine(currentLine);

      editor.replaceText(editor.getCurrentParagraph(), 0, editor.getCurrentParagraph(), currentLine.length(), newText);

    } else { // Comment selection

      String newText;
      if (Model.getLanguage().isCommentedSelection(editor.getSelectedText()))
        newText = Model.getLanguage().unCommentSelection(editor.getSelectedText());
      else
        newText = Model.getLanguage().commentSelection(editor.getSelectedText());

      editor.replaceSelection(newText);

    }
  }

  /**
   * Updates the wraptext setting of the code area
   * 
   * @param isWrapText The new value for the setting
   */
  private void setWrapText(boolean isWrapText) {
    this.editor.setWrapText(isWrapText);
  }

  /**
   * Handles the event whenever the content of the editor is changed.
   */
  private void editorChanged() {
    int offset = this.editor.getCaretPosition();
    Position pos = this.editor.offsetToPosition(offset, Bias.Forward);
    this.eventBus.post(new EditorChangedEvent(pos.getMajor() + 1, pos.getMinor()));

    if (Model.getFileIsSaved())
      this.eventBus.post(new FileSaveStateChangedEvent(false));

    this.refreshHighlighting();
  }

  /**
   * Updates the content of the editor to a specific filepath
   * 
   * @param filePath The path of the file
   * @throws FileNotFoundException
   */
  private void setEditorContent(String filePath) {
    if (filePath == null) {
      editor.clear();
      return;
    }
    try (Scanner sc = new Scanner(new File(filePath))) {
      if (filePath.endsWith(".java") || filePath.endsWith(".md")) {
        editor.clear();
        while (sc.hasNextLine()) {
          editor.appendText(sc.nextLine());
          editor.appendText("\n");
        }
      } else {
        throw new FileNotFoundException();
      }

    } catch (FileNotFoundException ex) {
      Alert error = new Alert(AlertType.ERROR);
      error.setContentText("Could not be opened!\nMust be a java or md file. Try again.");

      error.showAndWait();
      System.err.println(filePath);
    }
  }

  private void saveCodeArea(String filePath) {
    try (PrintWriter writer = new PrintWriter(new File(filePath))) {
      if (filePath.endsWith(".java") || filePath.endsWith(".md")) {
        writer.println(editor.getText());
      } else {
        throw new FileNotFoundException();
      }

    } catch (FileNotFoundException ex) {
      Alert error = new Alert(AlertType.ERROR);
      error.setContentText("Could not save file!\nMust be a java or md file. Try again.");

      error.showAndWait();
      System.err.println(filePath);
    }
  }

  @Subscribe
  private void handle(FileSelectedEvent event) {
    this.setEditorContent(event.getPath());
  }

  @Subscribe
  private void handle(SaveFile event) {
    this.saveCodeArea(event.getPath());
  }

  @Subscribe
  private void handle(LanguageChangedEvent event) {
    this.refreshHighlighting();
  }

  @Subscribe
  private void handle(ToggleCommentEvent event) {
    this.toggleComment();
  }

  @Subscribe
  private void handle(ToggleWrapTextEvent event) {
    this.setWrapText(event.getIsWrapped());
  }

  @Subscribe
  private void handle(UndoEvent event) {
    if (this.editor.isFocused())
      this.editor.undo();
  }

  @Subscribe
  private void handle(RedoEvent event) {
    if (this.editor.isFocused())
      this.editor.redo();
  }

  @Subscribe
  private void handle(CopyEvent event) {
    if (this.editor.isFocused())
      this.editor.copy();
  }

  @Subscribe
  private void handle(CutEvent event) {
    if (this.editor.isFocused())
      this.editor.cut();
  }

  @Subscribe
  private void handle(PasteEvent event) {
    if (this.editor.isFocused())
      this.editor.paste();
  }

}