import 'package:flutter/material.dart';

import 'cursor.dart';
import 'line_info.dart';

class CursorProvider extends ChangeNotifier {
  Cursor cursor = Cursor(line: 1, column: 0);
  bool inMouseSelection = false;

  int get line => cursor.line;
  int get column => cursor.column;

  void publishCursor(List<LineInfo> elements) {
    var ncursor = cursor.normalized();
    elements.forEach((element) {
      element.setCursor(ncursor);
    });
  }

  void moveCursorToDocStart() {
    clearSelection();
    cursor.line = 0;
    cursor.column = 0;
    cursor = cursor.normalized();
    notifyListeners();
  }

  void moveCursorToLineStart() {
    cursor.column = 0;
    notifyListeners();
  }

  void clearSelection() {
    inMouseSelection = false;
    cursor.anchorLine = cursor.line;
    cursor.anchorColumn = cursor.column;
    notifyListeners();
  }

  void moveCursorToLineEnd(int lineLength) {
    cursor.column = lineLength;
    notifyListeners();
  }

  void moveCursor(int dx, int dy, List<LineInfo> backingLines, {bool keepAnchor = false}) {
    //print(cursor.line.toString() + " " + cursor.column.toString() + " " + dx.toString() + " " + dy.toString() + " " + backingLines[cursor.line - 1].text.length.toString());

    if (dx != 0) {
      if (cursor.column + dx < 0) {
        moveCursor(0, -1, backingLines, keepAnchor: keepAnchor);
        if (cursor.line > 1) {
          moveCursorToLineEnd(backingLines[cursor.line - 1].text.length);
        }
      } else if (cursor.column + dx > backingLines[cursor.line - 1].text.length) {
        moveCursor(0, 1, backingLines, keepAnchor: keepAnchor);
        moveCursorToLineStart();
      } else {
        cursor.column += dx;
      }
    }

    if (dy != 0) {
      // Only allow the cursor line to change if in bounds
      if (cursor.line + dy > 0 && cursor.line + dy <= backingLines.length) {
        cursor.line += dy;
        // Change cursor to line end
        if (cursor.column > backingLines[cursor.line - 1].text.length) {
          moveCursorToLineEnd(backingLines[cursor.line - 1].text.length);
        }
      }
    }

    if (!keepAnchor) {
      clearSelection();
    }

    notifyListeners();
  }

  void mouseDownEnd() {
    inMouseSelection = false;
  }

  void mouseDownMoveUpdate(int col, List<LineInfo> backingLines) {
    if (cursor.column != col) {
      var lineLength = backingLines[cursor.line - 1].text.length;
      cursor.column = col.clamp(0, lineLength);
      if (inMouseSelection == false) {
        clearSelection();
      }
      publishCursor(backingLines);
    } else if (inMouseSelection == false) {
      clearSelection();
      publishCursor(backingLines);
    }
    inMouseSelection = true;
  }

  void mouseDownUpdate(int line, int col, List<LineInfo> backingLines) {
    if (cursor.line != line || cursor.column != col) {
      cursor.line = line;
      var lineLength = backingLines[cursor.line - 1].text.length;
      cursor.column = col.clamp(0, lineLength);
      if (inMouseSelection == false) {
        clearSelection();
      }
      publishCursor(backingLines);
    } else if (inMouseSelection == false) {
      clearSelection();
      publishCursor(backingLines);
    }
    inMouseSelection = true;
  }

  bool hasSelection() {
    return cursor.hasSelection();
  }

  Cursor normalized() {
    return cursor.normalized();
  }
}