import 'dart:ui';

import 'package:flutter/material.dart';

import 'package:time/time.dart';

class AutoCompletionWidget extends StatefulWidget {
  final FocusNode textFieldFocusNode;
  final GlobalKey textFieldKey;
  final TextStyle textFieldStyle;
  final TextEditingController textController;
  final Widget child;

  AutoCompletionWidget({
    @required this.textFieldFocusNode,
    @required this.textFieldKey,
    @required this.textFieldStyle,
    @required this.textController,
    @required this.child,
  });

  @override
  _AutoCompletionWidgetState createState() => _AutoCompletionWidgetState();
}

class _AutoCompletionWidgetState extends State<AutoCompletionWidget> {
  OverlayEntry overlayEntry;

  var autoCompleter = TagsAutoCompleter();

  @override
  void initState() {
    super.initState();
    widget.textController.addListener(_textChanged);
  }

  @override
  void dispose() {
    _hideOverlay();
    widget.textController.removeListener(_textChanged);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return widget.child;
  }

  void _textChanged() {
    var selection = widget.textController.selection;
    var text = widget.textController.text;

    var range = TextRange(0, 0);
    try {
      var es = EditorState(text, selection.baseOffset);
      range = autoCompleter.textChanged(es);
    } catch (e) {
      print(e);
      print("bah");
    }

    if (range.isEmpty) {
      _hideOverlay();
      return;
    }

    var prefix = text.substring(range.start, range.end);
    if (prefix == "\n") {
      // Pressed Enter
    } else {
      _showOverlayTag(context, text.substring(0, range.start));
    }
  }

  /// newText is used to calculate where to put the completion box
  void _showOverlayTag(BuildContext context, String newText) async {
    // Code reference for overlay logic from MTECHVIRAL's video
    // https://www.youtube.com/watch?v=KuXKwjv2gTY

    //print('showOverlaidTag: $newText');

    RenderBox renderBox = widget.textFieldKey.currentContext.findRenderObject();
    // print("render Box: ${renderBox.size}");

    TextPainter painter = TextPainter(
      textDirection: TextDirection.ltr,
      text: TextSpan(
        style: widget.textFieldStyle,
        text: newText,
      ),
      maxLines: null,
    );
    painter.layout(maxWidth: renderBox.size.width);

    List<LineMetrics> lines = painter.computeLineMetrics();
    double height = 0;
    for (var lm in lines) {
      height += lm.height;
    }
    double width = lines.last.width;

    //print("Focus Node Offset dx: ${_focusNode.offset.dx}");
    //print("Focus Node Offset dy: ${_focusNode.offset.dy}");

    //print("Painter ${painter.width} $height");

    _hideOverlay();
    overlayEntry = OverlayEntry(builder: (context) {
      return Positioned(
        // Decides where to place the tag on the screen.
        top: widget.textFieldFocusNode.offset.dy + height + 3,
        left: widget.textFieldFocusNode.offset.dx + width,

        // Tag code.
        child: const Material(
          elevation: 4.0,
          color: Colors.lightBlueAccent,
          child: Text(
            'Show tag here',
            style: TextStyle(
              fontSize: 20.0,
            ),
          ),
        ),
      );
    });
    Overlay.of(context).insert(overlayEntry);

    // Removes the over lay entry from the Overly after 500 milliseconds
    await Future.delayed(5000.milliseconds);
    _hideOverlay();
  }

  void _hideOverlay() {
    if (overlayEntry != null) {
      overlayEntry.remove();
      overlayEntry = null;
    }
  }
}

/*
/// if endToken is empty, then the token can only be alpha numeric
String extractToken(
    String text, int cursorPos, String startToken, String endToken) {
  var start = text.lastIndexOf(RegExp(r' '), cursorPos - 1);
  if (start == -1) {
    start = 0;
  }
  print("start: $start");

  var end = text.indexOf(RegExp(r' |$'), cursorPos);
  if (end == -1) {
    end = cursorPos;
  }
  print("end: $end");

  var word = text.substring(start, end);
  if (word.startsWith('[[')) {
    return word.substring(2, cursorPos);
  }

  return "";
}

bool enterPressed(String oldText, String newText, int cursorPos) {
  if (cursorPos <= 0) {
    return false;
  }

  var charEnterred = newText[cursorPos - 1];
  if (charEnterred == '\n') {
    return true;
  }
  return false;
}
*/

class EditorState {
  String text;
  int cursorPos;

  EditorState(this.text, this.cursorPos);
}

// https://levelup.gitconnected.com/flutter-medium-like-text-editor-b41157f50f0e
// https://stackoverflow.com/questions/59243627/flutter-how-to-get-the-coordinates-of-the-cursor-in-a-textfield

// Bug 2: Autocompletion box overlays the bottom nav bar
// Bug 3: On Pressing Enter the Overlay should disappear
// Bug 5: Overlay disappears too fast
// Bug 7: Clicking on the text should result in auto-completion
// Bug 8: On clicking somewhere else the suggestion box should disappear
// Bug 9: RTL support
// Bug  : What about when a letter is added to an existing tag with more words
//        or an existing wiki link which has the closing brackets
// Bug  : Show auto-completion on top if no space at the bottom
// Bug  : Handle physical tab or Enter key

/*
abstract class AutoCompletionLogic {
  /// Return an empty string if the overlay should be hidden
  /// Return \n if enter has been pressed
  /// Return the prefix if an overlay should be shown
  String textChanged(EditorState es);

  EditorState completeText(String text);
}
*/

/*
class WikiLinksAutoCompleter implements AutoCompletionLogic {
  var _oldState = EditorState("", 0);

  bool inBracket1 = false;
  bool inBracket2 = false;
  bool outBracket2 = false;

  var newText = "";

  @override
  void textChanged(EditorState es) {
    var oldState = _oldState;
    _oldState = es;

    // This could result in an Add / Remove / Replace

    if (es.text.length > oldState.text.length) {
      // Probably an add
      if (oldState.cursorPos < es.cursorPos) {
        newText = es.text.substring(oldState.cursorPos, es.cursorPos);
        return;
      }
      return;
    }
  }

  @override
  EditorState completeText(String text) {
    return null;
  }

  @override
  bool get enterPressed => false;

  @override
  bool get showOverlay => false;
}
*/

class TextRange {
  final int start;
  final int end;

  TextRange(this.start, this.end);

  bool get isEmpty => start == end;
}

class TagsAutoCompleter {
  TextRange textChanged(EditorState es) {
    // print("${es.text} ${es.cursorPos}");
    var start = es.text.lastIndexOf(RegExp(r'^|[ .?!:;\n]'), es.cursorPos);
    if (start <= 0) {
      start = 0;
    } else {
      start += 1;
    }
    if (start == es.text.length) {
      return TextRange(0, 0);
    }

    var end = es.text.indexOf(RegExp(r'[ .?!:;\n]|$'), es.cursorPos);
    if (end == -1) {
      end = es.cursorPos;
    }

    // print("start end: $start $end ${es.text.length}");
    // var text = es.text.substring(start, end);
    // print("text $text");
    if (es.text[start] != '#') {
      return TextRange(0, 0);
    }

    return TextRange(start + 1, end);
  }
}