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

<style lang="sass" scoped>
.diagram-container
  /deep/
    .area
      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
</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;

      let refWaterLevels = JSON.parse(
        this.selectedGauge.properties.reference_water_levels
      );

      let svgWidth = document.querySelector(".diagram-container").clientWidth;
      let svgHeight = document.querySelector(".diagram-container").clientHeight;
      d3.select(".diagram-container svg").remove();
      let svg = d3.select(".diagram-container").append("svg");
      svg.attr("width", "100%").attr("height", "100%");
      let margin = { top: 20, right: 20, bottom: 110, left: 40 },
        margin2 = {
          top: svgHeight - margin.top - 50,
          right: 20,
          bottom: 30,
          left: 40
        },
        width = +svgWidth - margin.left - margin.right,
        height = +svgHeight - margin.top - margin.bottom,
        height2 = +svgHeight - margin2.top - margin2.bottom;

      let x = d3.scaleTime().range([0, width]),
        x2 = d3.scaleTime().range([0, width]),
        y = d3.scaleLinear().range([height, 0]),
        y2 = d3.scaleLinear().range([height2, 0]);

      let xAxis = d3.axisBottom(x),
        xAxis2 = d3.axisBottom(x2),
        yAxis = d3.axisLeft(y);

      // find min/max values for the waterlevel axis
      // based on hdc/ldc +/- 100 cm
      let xMinMax = d3.extent(
        [
          ...this.waterlevels,
          { waterlevel: refWaterLevels.HDC + 100 },
          { waterlevel: Math.max(refWaterLevels.LDC - 100, 0) }
        ],
        function(d) {
          return d.waterlevel;
        }
      );

      x.domain(
        d3.extent(this.waterlevels, function(d) {
          return d.date;
        })
      );
      y.domain(xMinMax);
      x2.domain(x.domain());
      y2.domain(y.domain());

      let brush = d3
        .brushX()
        .handleSize(4)
        .extent([[0, 0], [width, height2]])
        .on("brush end", brushed);

      let zoom = d3
        .zoom()
        .scaleExtent([1, Infinity])
        .translateExtent([[0, 0], [width, height]])
        .extent([[0, 0], [width, height]])
        .on("zoom", zoomed);

      // waterlevel line in big chart
      let area = d3
        .line()
        .curve(d3.curveMonotoneX)
        .x(function(d) {
          return x(d.date);
        })
        .y(function(d) {
          return y(d.waterlevel);
        });

      // waterlevel line in small chart
      let area2 = d3
        .line()
        .curve(d3.curveMonotoneX)
        .x(function(d) {
          return x2(d.date);
        })
        .y(function(d) {
          return y2(d.waterlevel);
        });

      let refWaterlevelLine = d3
        .line()
        .x(d => x(d.x))
        .y(d => y(d.y));

      svg
        .append("defs")
        .append("clipPath")
        .attr("id", "clip")
        .append("rect")
        .attr("width", width)
        .attr("height", height);

      let focus = svg
        .append("g")
        .attr("class", "focus")
        .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

      let context = svg
        .append("g")
        .attr("class", "context")
        .attr(
          "transform",
          "translate(" + margin2.left + "," + margin2.top + ")"
        );

      focus
        .append("path")
        .datum(this.waterlevels)
        .attr("class", "area")
        .attr("d", area);

      focus
        .append("path")
        .datum([
          { x: 0, y: refWaterLevels.HDC },
          {
            x: this.waterlevels[this.waterlevels.length - 1].date,
            y: refWaterLevels.HDC
          }
        ])
        .attr("class", "hdc-line")
        .attr("d", refWaterlevelLine);

      focus
        .append("path")
        .datum([
          { x: 0, y: refWaterLevels.LDC },
          {
            x: this.waterlevels[this.waterlevels.length - 1].date,
            y: refWaterLevels.LDC
          }
        ])
        .attr("class", "ldc-line")
        .attr("d", refWaterlevelLine);

      focus
        .append("path")
        .datum([
          { x: 0, y: refWaterLevels.MW },
          {
            x: this.waterlevels[this.waterlevels.length - 1].date,
            y: refWaterLevels.MW
          }
        ])
        .attr("class", "mw-line")
        .attr("d", refWaterlevelLine);

      focus
        .append("g")
        .attr("class", "axis axis--x")
        .attr("transform", "translate(0," + height + ")")
        .call(xAxis);

      focus
        .append("g")
        .attr("class", "axis axis--y")
        .call(yAxis);

      context
        .append("path")
        .datum(this.waterlevels)
        .attr("class", "area")
        .attr("d", area2);

      context
        .append("g")
        .attr("class", "axis axis--x")
        .attr("transform", "translate(0," + height2 + ")")
        .call(xAxis2);

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

      svg
        .append("rect")
        .attr("class", "zoom")
        .attr("width", width)
        .attr("height", height)
        .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
        .call(zoom);

      function brushed() {
        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));
        focus.select(".area").attr("d", area);
        focus.select(".axis--x").call(xAxis);
        svg
          .select(".zoom")
          .call(
            zoom.transform,
            d3.zoomIdentity.scale(width / (s[1] - s[0])).translate(-s[0], 0)
          );
      }

      function zoomed() {
        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());
        focus.select(".area").attr("d", area);
        focus.select(".axis--x").call(xAxis);
        context.select(".brush").call(brush.move, x.range().map(t.invertX, t));
      }
    }
  },
  created() {
    window.addEventListener("resize", debounce(this.drawDiagram), 100);
  },
  mounted() {
    this.drawDiagram();
  },
  updated() {
    this.drawDiagram();
  }
};
</script>