/*
 * Copyright (C) 2017, David PHAM-VAN <dev.nfet.net@gmail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// ignore_for_file: omit_local_variable_types

part of widget;

class LinearGrid extends ChartGrid {
  LinearGrid({
    @required this.xAxis,
    @required this.yAxis,
    this.xMargin = 10,
    this.yMargin = 2,
    this.textStyle,
    this.lineWidth = 1,
    this.color = PdfColors.black,
    this.separatorLineWidth = .5,
    this.separatorColor = PdfColors.grey,
  })  : assert(_isSortedAscending(xAxis)),
        assert(_isSortedAscending(yAxis));

  final List<double> xAxis;
  final List<double> yAxis;
  final double xMargin;
  final double yMargin;
  final TextStyle textStyle;
  final double lineWidth;
  final PdfColor color;
  final double separatorLineWidth;
  final PdfColor separatorColor;

  TextStyle style;
  PdfFont font;
  PdfFontMetrics xAxisFontMetric;
  PdfFontMetrics yAxisFontMetric;
  PdfRect gridBox;
  double xOffset;
  double xTotal;
  double yOffset;
  double yTotal;

  static bool _isSortedAscending(List<double> list) {
    double prev = list.first;
    for (double elem in list) {
      if (prev > elem) {
        return false;
      }
      prev = elem;
    }
    return true;
  }

  @override
  PdfPoint tochart(PdfPoint p) {
    return PdfPoint(
      gridBox.left + gridBox.width * (p.x - xOffset) / xTotal,
      gridBox.bottom + gridBox.height * (p.y - yOffset) / yTotal,
    );
  }

  @override
  void layout(Context context, PdfPoint size) {
    style = Theme.of(context).defaultTextStyle.merge(textStyle);
    font = style.font.getFont(context);

    xAxisFontMetric =
        font.stringMetrics(xAxis.reduce(math.max).toStringAsFixed(1)) *
            (style.fontSize);
    yAxisFontMetric =
        font.stringMetrics(yAxis.reduce(math.max).toStringAsFixed(1)) *
            (style.fontSize);

    gridBox = PdfRect.fromLTRB(
        yAxisFontMetric.width + xMargin,
        xAxisFontMetric.height + yMargin,
        size.x - xAxisFontMetric.width / 2,
        size.y - yAxisFontMetric.height / 2);

    xOffset = xAxis.reduce(math.min);
    yOffset = yAxis.reduce(math.min);
    xTotal = xAxis.reduce(math.max) - xOffset;
    yTotal = yAxis.reduce(math.max) - yOffset;
  }

  @override
  void paintBackground(Context context, PdfPoint size) {
    xAxis.asMap().forEach((int i, double x) {
      context.canvas
        ..setColor(style.color)
        ..drawString(
          style.font.getFont(context),
          style.fontSize,
          x.toStringAsFixed(1),
          gridBox.left +
              gridBox.width * i / (xAxis.length - 1) -
              xAxisFontMetric.width / 2,
          0,
        );
    });

    for (double y in yAxis.where((double y) => y != yAxis.first)) {
      final double textWidth =
          (font.stringMetrics(y.toStringAsFixed(1)) * (style.fontSize)).width;
      final double yPos = gridBox.bottom + gridBox.height * y / yAxis.last;
      context.canvas
        ..setColor(style.color)
        ..drawString(
          style.font.getFont(context),
          style.fontSize,
          y.toStringAsFixed(1),
          xAxisFontMetric.width / 2 - textWidth / 2,
          yPos - font.ascent,
        );

      context.canvas.drawLine(
          gridBox.left,
          yPos + font.descent + font.ascent - separatorLineWidth / 2,
          gridBox.right,
          yPos + font.descent + font.ascent - separatorLineWidth / 2);
    }
    context.canvas
      ..setStrokeColor(separatorColor)
      ..setLineWidth(separatorLineWidth)
      ..strokePath();

    context.canvas
      ..setStrokeColor(color)
      ..setLineWidth(lineWidth)
      ..drawLine(gridBox.left, gridBox.bottom, gridBox.right, gridBox.bottom)
      ..drawLine(gridBox.left, gridBox.bottom, gridBox.left, gridBox.top)
      ..strokePath();
  }

  @override
  void paintForeground(Context context, PdfPoint size) {}
}