class BBTimelineBackgroundCanvas extends BBTimelineCanvas {
  constructor(parentEl, el) {
    super(parentEl, el);
  }

  initialiseOptions() {
    super.initialiseOptions();

    const a = this;

    a.Options = {
      Axis: {
        LineColour1: "#000000",
        LineWidth: 1,
        Font: "8pt Arial",
        LabelColour: "#000000",
        LabelSpacing: 6
      },
      XAxis: {
        NoPartPerDay: 4,
        HourLineSpace: 6,
        HourLineHeight: 10,
        HourLineColour: "#EAEAEA",
        DayLineHeight: 20,
        DayLineColour: "#9E9E9E",
        Position: 'bottom'
      }
    };
  }

  initialiseComponents() {
    super.initialiseComponents();

    const a = this;

    a.Invalidate();
  }


  get GraphRectangle() {
    const a = this;

    if (a.Options.XAxis.Position == 'top') {
      return {
        X: a.ClientRectangle.X,
        Y: (a.ClientRectangle.Y + a.XAxisHeight),
        W: a.ClientRectangle.W,
        H: (a.ClientRectangle.H - a.XAxisHeight)
      };
    } else {
      return {
        X: a.ClientRectangle.X,
        Y: a.ClientRectangle.Y,
        W: a.ClientRectangle.W,
        H: (a.ClientRectangle.H - a.XAxisHeight)
      };
    }
  }

  get XAxisHeight() {
    const a  = this;
    const labelSize = a.measureText(a.Options.Axis.Font, "0");

    return labelSize.H + a.Options.Axis.LabelSpacing + (a.Options.XAxis.DayLineHeight * 2);
  }

  get XAxisPositions() {
    const a = this;
    const endPosX = (a.GraphRectangle.X + a.GraphRectangle.W);

    let result = [];
    let x = a.GraphRectangle.X;
    let date = a.Parent.ConvertToDate(a.Parent.ShowDate);

    // Rollback one day
    date.setDate(date.getDate() - 1);

    while (true) {
      if (x >= endPosX) {
        break;
      }

      result.push({
        Date: a.Parent.DateToInternalString(date),
        X: x
      });

      x += (a.Options.XAxis.HourLineSpace * a.Options.XAxis.NoPartPerDay);
      date.setDate(date.getDate() + 1);
    }

    return result;
  }


  Invalidate() {
    const a = this;

    a.Clear();

    a.drawAxis();
    a.drawXAxisTicks();
    a.drawXAxisLabels();

    if (a.Parent.Debug) a.drawRectangle(a.ClientRectangle, "red");
    if (a.Parent.Debug) a.drawRectangle(a.GraphRectangle, "red");
  }


  drawAxis() {
    const a = this;

    a.CTX.beginPath();

    if (a.Options.XAxis.Position == 'top') {
      a.CTX.moveTo(a.GraphRectangle.X, (a.GraphRectangle.Y + a.GraphRectangle.H));
      a.CTX.lineTo(a.GraphRectangle.X, a.GraphRectangle.Y);
      a.CTX.lineTo((a.GraphRectangle.X + a.GraphRectangle.W), a.GraphRectangle.Y);
    } else {
      a.CTX.moveTo(a.GraphRectangle.X, a.GraphRectangle.Y);
      a.CTX.lineTo(a.GraphRectangle.X, (a.GraphRectangle.Y +a.GraphRectangle.H));
      a.CTX.lineTo((a.GraphRectangle.X + a.GraphRectangle.W), (a.GraphRectangle.Y + a.GraphRectangle.H));
    }

    a.CTX.lineWidth = a.Options.Axis.LineWidth;
    a.CTX.strokeStyle = a.Options.Axis.LineColour1;
    a.CTX.stroke();
  }

  drawXAxisLabels() {
    const a = this;
    const labelSize = a.measureText(a.Options.Axis.Font, "0");

    let posY = 0;
    let posDayY = 0;
    let posMonthY = 0;

    if (a.Options.XAxis.Position == 'top') {
      posY = (a.GraphRectangle.Y - a.Options.Axis.LineWidth) - 2;
      posDayY = (posY - (labelSize.H + a.Options.XAxis.DayLineHeight));
      posMonthY = (posDayY - (labelSize.H + a.Options.Axis.LabelSpacing));
    } else {
      posY = (a.GraphRectangle.Y + a.GraphRectangle.H) + a.Options.Axis.LineWidth;
      posDayY = (posY + a.Options.XAxis.DayLineHeight);
      posMonthY = (posDayY + labelSize.H + a.Options.Axis.LabelSpacing);
    }

    a.XAxisPositions.forEach(function(e, i) {
      const date = a.Parent.ConvertToDate(e.Date);

      let writeLabel = false;
      if ((i == 0)) {
        // Don't label first entry if too close to the next month
        if (date.getDate() < 25) {
          writeLabel = true;
        }
      } else if (date.getDate() == 1) {
        writeLabel = true;
      }

      // if (i == 0) {
      //   // Don't write first date
      // } else {
        // Write date (dd)
        a.drawText(e.X, posDayY, a.Parent.DateToString(date, "dd"), a.Options.Axis.Font, a.Options.Axis.LabelColour, "center");
      // }

      // Write month (MMMM) on first of the month
      if (writeLabel) {
        a.drawText(e.X, posMonthY, a.Parent.DateToString(date, "MMMM yyyy"), a.Options.Axis.Font, a.Options.Axis.LabelColour, "left");
      }
    });
  }

  drawXAxisTicks() {
    const a = this;

    let startPosX = a.GraphRectangle.X;
    const endPosX = (a.GraphRectangle.X + a.GraphRectangle.W);
    let posY = 0;
    let posDayY = 0;
    let posHourY = 0;

    if (a.Options.XAxis.Position == 'top') {
      posY = (a.GraphRectangle.Y - a.Options.Axis.LineWidth);
      posDayY = (posY - a.Options.XAxis.DayLineHeight);
      posHourY = (posY - a.Options.XAxis.HourLineHeight);
    } else {
      posY = (a.GraphRectangle.Y + a.GraphRectangle.H) + a.Options.Axis.LineWidth;
      posDayY = (posY + a.Options.XAxis.DayLineHeight);
      posHourY = (posY + a.Options.XAxis.HourLineHeight);
    }

    let i = 0;

    while (true) {
      if (startPosX >= endPosX) {
        break;
      }

      a.CTX.beginPath();
      a.CTX.moveTo(startPosX, posY);

      if ((i % a.Options.XAxis.NoPartPerDay) == 0) {
        a.CTX.lineTo(startPosX, posDayY);
        a.CTX.strokeStyle = a.Options.XAxis.DayLineColour;
      } else {
        a.CTX.lineTo(startPosX, posHourY);
        a.CTX.strokeStyle = a.Options.XAxis.HourLineColour;
      }

      a.CTX.lineWidth = a.Options.Axis.LineWidth;
      a.CTX.stroke();

      startPosX += a.Options.XAxis.HourLineSpace;

      i++;
    }
  }

}