/// <reference path="./d3.js" />

const ASPECT_RATIO = window.innerWidth / window.innerHeight;
const CANVAS_WIDTH = window.innerWidth ?? 1000;
// *0.9 for footer
const CANVAS_HEIGHT =
  (ASPECT_RATIO > 1
    ? window.innerHeight * 0.9
    : CANVAS_WIDTH * ASPECT_RATIO * 0.9) ?? 500;
const CHART_WIDTH = CANVAS_WIDTH * 0.8;
const CHART_HEIGHT = CANVAS_HEIGHT * 0.8;
const CHART_X_OFFSET = (CANVAS_WIDTH - CHART_WIDTH) / 2;
const CHART_Y_OFFSET = (CANVAS_HEIGHT - CHART_HEIGHT) / 2;

const fetchData = async () => {
  return await (await fetch("./data.json")).json();
};

const getQuarter = (month) => {
  if (month >= 1 && month <= 3) return 1;
  else if (month >= 4 && month <= 6) return 2;
  else if (month >= 7 && month <= 9) return 3;
  else if (month >= 10 && month <= 12) return 4;
  else throw Error("Month out of range: " + month);
};

const parseDate = (date) => {
  const [year, month] = date.split("-");
  const quarter = getQuarter(Number(month)).toString();
  return year + " Q" + quarter;
};

const parseYear = (date) => Number(date.split("-")[0]);

fetchData()
  .then((dataset) => {
    const MAX_GDP = Number(d3.max(dataset.data, (d) => d[1]));
    const BAR_WIDTH = CHART_WIDTH / dataset.data.length;
    const yScale = (gdp) => (gdp / MAX_GDP) * CHART_HEIGHT;
    const xAxisScale = d3
      .scaleLinear()
      .domain([
        parseYear(dataset.data[0][0]),
        parseYear(dataset.data.at(-1)[0]),
      ])
      .range([0, CHART_WIDTH]);
    const yAxisScale = d3
      .scaleLinear()
      .domain([0, MAX_GDP])
      .range([CHART_HEIGHT, 0]);

    const canvas = d3
      .select("body")
      .append("svg")
      .attr("width", CANVAS_WIDTH)
      .attr("height", CANVAS_HEIGHT);

    const mouseover = (e) => {
      const { date, gdp } = e.target.dataset;
      tooltip
        .html(`${parseDate(date)}<br/>$${Number(gdp).toLocaleString()} Billion`)
        .style("opacity", 1)
        .attr("data-date", date)
        .attr("data-gdp", gdp);
    };

    const mousemove = (e) => {
      tooltip.style("left", e.pageX + "px").style("top", e.pageY + "px");
    };

    const mouseleave = (d) => {
      tooltip.style("opacity", 0);
    };

    canvas
      .append("text")
      .attr("id", "title")
      .attr("x", "50%")
      .attr("text-anchor", "middle")
      .attr("y", CHART_Y_OFFSET * 0.9)
      .attr("font-size", CHART_Y_OFFSET * 0.8)
      .text("United States GDP");

    canvas
      .selectAll("rect")
      .data(dataset.data)
      .enter()
      .append("rect")
      .attr("class", "bar")
      .attr("data-date", (d) => d[0])
      .attr("data-gdp", (d) => d[1])
      .attr("height", (d) => yScale(d[1]))
      .attr("width", BAR_WIDTH)
      .attr("x", (_, i) => i * BAR_WIDTH + CHART_X_OFFSET)
      .attr("y", (d) => CHART_Y_OFFSET + CHART_HEIGHT - yScale(d[1]))
      .on("mouseover", mouseover)
      .on("mousemove", mousemove)
      .on("mouseleave", mouseleave);

    canvas
      .append("g")
      .attr("id", "x-axis")
      .style("font", CHART_Y_OFFSET * 0.3 + "px quicksand")
      .attr(
        "transform",
        `translate(${CHART_X_OFFSET}, ${CHART_HEIGHT + CHART_Y_OFFSET})`
      )
      .call(d3.axisBottom(xAxisScale).tickFormat(d3.format("d")));

    canvas
      .append("g")
      .attr("id", "y-axis")
      .style("font", CHART_Y_OFFSET * 0.3 + "px quicksand")
      .attr("transform", `translate(${CHART_X_OFFSET}, ${CHART_Y_OFFSET})`)
      .call(d3.axisLeft(yAxisScale));

    let tooltip = d3
      .select("body")
      .append("div")
      .attr("id", "tooltip")
      .attr("class", "tooltip")
      .attr("data-date", "")
      .attr("data-gdp", "")
      .style("opacity", 0)
      .style("position", "absolute")
      .style("font", CHART_Y_OFFSET * 0.3 + "px");

    canvas
      .append("text")
      .attr("id", "y-label")
      .style("font-size", CHART_Y_OFFSET * 0.3 + "px")
      .attr("text-anchor", "end")
      .attr("y", CHART_X_OFFSET * 0.2)
      .attr("x", -CHART_Y_OFFSET - CHART_HEIGHT / 2)
      .attr("text-anchor", "middle")
      .attr("transform", "rotate(-90)")
      .text("Gross Domestic Product (GDP) in Billions");

    canvas
      .append("text")
      .attr("id", "x-label")
      .attr("x", "50%")
      .attr("y", CHART_HEIGHT + CHART_Y_OFFSET * 1.9)
      .attr("text-anchor", "middle")
      .style("font-size", CHART_Y_OFFSET * 0.3 + "px")
      .text("Quarterly");

    d3.select("body")
      .append("footer")
      .style("bottom", CHART_Y_OFFSET * 0.1 + "px")
      .style("font-size", CHART_Y_OFFSET * 0.25 + "px")
      .append("p")
      .append("a")
      .attr(
        "href",
        "https://radii.dev/freecodecamp-data-visualization/bar-chart"
      )
      .text("</> Source Code & License");
  })
  .catch((e) => console.error("Error occurred!", e));