<template>
  <div class="flex-fill diagram-container"></div>
</template>

<style lang="sass" scoped>
.diagram-container
  /deep/
    .line
      stroke: steelblue
      stroke-width: 2
      fill: transparent
      clip-path: url(#clip)

    .zoom
      cursor: move
      fill: none
      pointer-events: all

    .hdc-line,
    .ldc-line,
    .mw-line
      stroke-width: 1
      fill: transparent
      clip-path: url(#clip)
    .hdc-line
      stroke: red
    .ldc-line
      stroke: green
    .mw-line
      stroke: grey
    .brush
      .selection
        stroke: transparent
        fill-opacity: 0.2
      .handle
        fill: rgba($color-info, 0.5)
</style>

<script>
/* This is Free Software under GNU Affero General Public License v >= 3.0
 * without warranty, see README.md and license for details.
 *
 * SPDX-License-Identifier: AGPL-3.0-or-later
 * License-Filename: LICENSES/AGPL-3.0.txt
 *
 * Copyright (C) 2018 by via donau
 *   – Österreichische Wasserstraßen-Gesellschaft mbH
 * Software engineering by Intevation GmbH
 *
 * Author(s):
 * Markus Kottländer <markus.kottlaender@intevation.de>
 */

import { mapState, mapGetters } from "vuex";
import * as d3 from "d3";
import debounce from "debounce";

export default {
  computed: {
    ...mapState("gauges", ["waterlevels"]),
    ...mapGetters("gauges", ["selectedGauge"])
  },
  watch: {
    waterlevels() {
      this.drawDiagram();
    }
  },
  methods: {
    drawDiagram() {
      if (!this.selectedGauge || !this.waterlevels.length) return;

      // remove old diagram
      d3.select(".diagram-container svg").remove();

      // get HDC/LDC/MW of the gauge
      let refWaterLevels = JSON.parse(
        this.selectedGauge.properties.reference_water_levels
      );

      // CREATE SVG AND SET DIMENSIONS/MARGINS

      let svgWidth = document.querySelector(".diagram-container").clientWidth;
      let svgHeight = document.querySelector(".diagram-container").clientHeight;
      let svg = d3
        .select(".diagram-container")
        .append("svg")
        .attr("width", "100%")
        .attr("height", "100%");
      let mainMargin = { top: 50, right: 20, bottom: 110, left: 40 },
        navMargin = {
          top: svgHeight - mainMargin.top - 35,
          right: 20,
          bottom: 30,
          left: 40
        },
        width = +svgWidth - mainMargin.left - mainMargin.right,
        mainHeight = +svgHeight - mainMargin.top - mainMargin.bottom,
        navHeight = +svgHeight - navMargin.top - navMargin.bottom;

      // PREPARING AXES/SCALING

      // scaling helpers to convert real values to pixels
      // based on the diagrams dimensions
      let x = d3.scaleTime().range([0, width]),
        x2 = d3.scaleTime().range([0, width]),
        y = d3.scaleLinear().range([mainHeight, 0]),
        y2 = d3.scaleLinear().range([navHeight, 0]);
      // find min/max values for the waterlevel axis
      // including hdc/ldc (+/- 100 cm)
      let WaterlevelMinMax = d3.extent(
        [
          ...this.waterlevels,
          { waterlevel: refWaterLevels.HDC + 100 },
          { waterlevel: Math.max(refWaterLevels.LDC - 100, 0) }
        ],
        d => d.waterlevel
      );
      // setting the min and max values for the diagram axes
      x.domain(d3.extent(this.waterlevels, d => d.date));
      y.domain(WaterlevelMinMax);
      x2.domain(x.domain());
      y2.domain(y.domain());
      // creating the axes based on these scales
      let xAxis = d3.axisBottom(x),
        xAxis2 = d3.axisBottom(x2),
        yAxis = d3.axisLeft(y);

      // PREPARING CHART FUNCTIONS

      // waterlevel line in big chart
      let mainLineChart = d3
        .line()
        .curve(d3.curveMonotoneX)
        .x(d => x(d.date))
        .y(d => y(d.waterlevel));
      // waterlevel line in small chart
      let navLineChart = d3
        .line()
        .curve(d3.curveMonotoneX)
        .x(d => x2(d.date))
        .y(d => y2(d.waterlevel));
      // hdc/ldc/mw
      let refWaterlevelLine = d3
        .line()
        .x(d => x(d.x))
        .y(d => y(d.y));

      // DRAWING MAINCHART

      // define visible area
      // everything outside this area will be hidden (clipped)
      svg
        .append("defs")
        .append("clipPath")
        .attr("id", "clip")
        .append("rect")
        .attr("width", width)
        .attr("height", mainHeight);

      let mainChart = svg
        .append("g")
        .attr("transform", `translate(${mainMargin.left}, ${mainMargin.top})`);

      // axes
      mainChart
        .append("g")
        .attr("transform", `translate(0, ${mainHeight})`)
        .call(xAxis);
      mainChart.append("g").call(yAxis);

      // waterlevel chart
      mainChart
        .append("path")
        .datum(this.waterlevels)
        .attr("class", "line")
        .attr("d", mainLineChart);

      // reference waterlevels
      let lastDate = this.waterlevels[this.waterlevels.length - 1].date;
      mainChart
        .append("path")
        .datum([
          { x: 0, y: refWaterLevels.HDC },
          { x: lastDate, y: refWaterLevels.HDC }
        ])
        .attr("class", "hdc-line")
        .attr("d", refWaterlevelLine);
      mainChart
        .append("path")
        .datum([
          { x: 0, y: refWaterLevels.LDC },
          { x: lastDate, y: refWaterLevels.LDC }
        ])
        .attr("class", "ldc-line")
        .attr("d", refWaterlevelLine);
      mainChart
        .append("path")
        .datum([
          { x: 0, y: refWaterLevels.MW },
          { x: lastDate, y: refWaterLevels.MW }
        ])
        .attr("class", "mw-line")
        .attr("d", refWaterlevelLine);

      // DRAWING NAVCHART

      let navChart = svg
        .append("g")
        .attr("transform", `translate(${navMargin.left}, ${navMargin.top})`);

      // axis (nav chart only has y-axis)
      navChart
        .append("g")
        .attr("class", "axis axis--x")
        .attr("transform", `translate(0, ${navHeight})`)
        .call(xAxis2);

      // waterlevel chart
      navChart
        .append("path")
        .datum(this.waterlevels)
        .attr("class", "line")
        .attr("d", navLineChart);

      // INTERACTIVITY

      // selecting time period in nav chart
      let brush = d3
        .brushX()
        .handleSize(4)
        .extent([[0, 0], [width, navHeight]])
        .on("brush end", () => {
          if (d3.event.sourceEvent && d3.event.sourceEvent.type === "zoom")
            return; // ignore brush-by-zoom
          let s = d3.event.selection || x2.range();
          x.domain(s.map(x2.invert, x2));
          mainChart.select(".line").attr("d", mainLineChart);
          mainChart.select(".axis--x").call(xAxis);
          svg
            .select(".zoom")
            .call(
              zoom.transform,
              d3.zoomIdentity.scale(width / (s[1] - s[0])).translate(-s[0], 0)
            );
        });

      // zooming with mousewheel in main chart
      let zoom = d3
        .zoom()
        .scaleExtent([1, Infinity])
        .translateExtent([[0, 0], [width, mainHeight]])
        .extent([[0, 0], [width, mainHeight]])
        .on("zoom", () => {
          if (d3.event.sourceEvent && d3.event.sourceEvent.type === "brush")
            return; // ignore zoom-by-brush
          let t = d3.event.transform;
          x.domain(t.rescaleX(x2).domain());
          mainChart.select(".line").attr("d", mainLineChart);
          mainChart.select(".axis--x").call(xAxis);
          navChart
            .select(".brush")
            .call(brush.move, x.range().map(t.invertX, t));
        });

      navChart
        .append("g")
        .attr("class", "brush")
        .call(brush)
        .call(brush.move, x.range());

      svg
        .append("rect")
        .attr("class", "zoom")
        .attr("width", width)
        .attr("height", mainHeight)
        .attr("transform", `translate(${mainMargin.left}, ${mainMargin.top})`)
        .call(zoom);
    }
  },
  created() {
    window.addEventListener("resize", debounce(this.drawDiagram), 100);
  },
  mounted() {
    this.drawDiagram();
  },
  updated() {
    this.drawDiagram();
  }
};
</script>