import { callHistoricalAPI, callReferrersAPI } from './client';

const activeCharts = {};

function resetActive(activeButton) {
  const buttons = document.querySelectorAll(
    '.crayons-tabs--analytics .crayons-tabs__item',
  );
  for (let i = 0; i < buttons.length; i += 1) {
    const button = buttons[i];
    button.classList.remove('crayons-tabs__item--current');
    button.removeAttribute('aria-current');
  }

  activeButton.classList.add('crayons-tabs__item--current');
  activeButton.setAttribute('aria-current', 'page');
}

function sumAnalytics(data, key) {
  return Object.entries(data).reduce((sum, day) => sum + day[1][key].total, 0);
}

function cardHTML(stat, header) {
  return `
    <h4>${header}</h4>
    <div class="featured-stat">${stat}</div>
  `;
}

function writeCards(data, timeRangeLabel) {
  const readers = sumAnalytics(data, 'page_views');
  const reactions = sumAnalytics(data, 'reactions');
  const comments = sumAnalytics(data, 'comments');

  const reactionCard = document.getElementById('reactions-card');
  const commentCard = document.getElementById('comments-card');
  const readerCard = document.getElementById('readers-card');

  readerCard.innerHTML = cardHTML(readers, `Readers ${timeRangeLabel}`);
  commentCard.innerHTML = cardHTML(comments, `Comments ${timeRangeLabel}`);
  reactionCard.innerHTML = cardHTML(reactions, `Reactions ${timeRangeLabel}`);
}

function drawChart({ id, showPoints = true, title, labels, datasets }) {
  const chartOptions = {
    elements: {
      point: {
        // The default is 3: https://www.chartjs.org/docs/latest/configuration/elements.html#point-configuration
        radius: showPoints ? 3 : 0,
      },
    },
    scales: {
      y: {
        type: 'linear',
        suggestedMin: 0,
        ticks: {
          precision: 0,
        },
      },
    },
  };
  const dataOptions = {
    plugins: {
      legend: {
        position: 'top',
      },
    },
    responsive: true,
    title: {
      display: true,
      text: title,
    },
  };

  import('chart.js').then(
    ({
      Chart,
      LineController,
      LinearScale,
      CategoryScale,
      PointElement,
      LineElement,
      Legend,
    }) => {
      Chart.register(
        LineController,
        LinearScale,
        CategoryScale,
        PointElement,
        LineElement,
        Legend,
      );
      const currentChart = activeCharts[id];
      if (currentChart) {
        currentChart.destroy();
      }

      const canvas = document.getElementById(id);
      // eslint-disable-next-line no-new
      activeCharts[id] = new Chart(canvas, {
        type: 'line',
        data: {
          labels,
          datasets,
          options: dataOptions,
        },
        options: chartOptions,
      });
    },
  );
}

function drawCharts(data, timeRangeLabel) {
  const labels = Object.keys(data);
  const parsedData = Object.entries(data).map((date) => date[1]);
  const comments = parsedData.map((date) => date.comments.total);
  const reactions = parsedData.map((date) => date.reactions.total);
  const likes = parsedData.map((date) => date.reactions.like);
  const readingList = parsedData.map((date) => date.reactions.readinglist);
  const unicorns = parsedData.map((date) => date.reactions.unicorn);
  const readers = parsedData.map((date) => date.page_views.total);

  // When timeRange is "Infinity" we hide the points to avoid over-crowding the UI
  const showPoints = timeRangeLabel !== '';

  drawChart({
    id: 'reactions-chart',
    showPoints,
    title: `Reactions ${timeRangeLabel}`,
    labels,
    datasets: [
      {
        label: 'Total',
        data: reactions,
        fill: false,
        borderColor: 'rgb(75, 192, 192)',
        backgroundColor: 'rgb(75, 192, 192)',
        lineTension: 0.1,
      },
      {
        label: 'Likes',
        data: likes,
        fill: false,
        borderColor: 'rgb(229, 100, 100)',
        backgroundColor: 'rgb(229, 100, 100)',
        lineTension: 0.1,
      },
      {
        label: 'Unicorns',
        data: unicorns,
        fill: false,
        borderColor: 'rgb(157, 57, 233)',
        backgroundColor: 'rgb(157, 57, 233)',
        lineTension: 0.1,
      },
      {
        label: 'Bookmarks',
        data: readingList,
        fill: false,
        borderColor: 'rgb(10, 133, 255)',
        backgroundColor: 'rgb(10, 133, 255)',
        lineTension: 0.1,
      },
    ],
  });

  drawChart({
    id: 'comments-chart',
    showPoints,
    title: `Comments ${timeRangeLabel}`,
    labels,
    datasets: [
      {
        label: 'Comments',
        data: comments,
        fill: false,
        borderColor: 'rgb(75, 192, 192)',
        backgroundColor: 'rgb(75, 192, 192)',
        lineTension: 0.1,
      },
    ],
  });

  drawChart({
    id: 'readers-chart',
    showPoints,
    title: `Reads ${timeRangeLabel}`,
    labels,
    datasets: [
      {
        label: 'Reads',
        data: readers,
        fill: false,
        borderColor: 'rgb(157, 57, 233)',
        backgroundColor: 'rgb(157, 57, 233)',
        lineTension: 0.1,
      },
    ],
  });
}

function renderReferrers(data) {
  const container = document.getElementById('referrers-container');
  const tableBody = data.domains
    .filter((referrer) => referrer.domain)
    .map((referrer) => {
      return `
      <tr>
        <td class="align-left">${referrer.domain}</td>
        <td class="align-right">${referrer.count}</td>
      </tr>
    `;
    });

  // add referrers with empty domains if present
  const emptyDomainReferrer = data.domains.filter(
    (referrer) => !referrer.domain,
  )[0];
  if (emptyDomainReferrer) {
    tableBody.push(`
      <tr>
        <td class="align-left">All other external referrers</td>
        <td class="align-right">${emptyDomainReferrer.count}</td>
      </tr>
    `);
  }

  container.innerHTML = tableBody.join('');
}

function removeCardElements() {
  const el = document.getElementsByClassName('summary-stats')[0];
  el && el.remove();
}

function showErrorsOnCharts() {
  const target = ['reactions-chart', 'comments-chart', 'readers-chart'];
  target.forEach((id) => {
    const el = document.getElementById(id);
    el.outerHTML = `<p class="m-5" id="${id}">Failed to fetch chart data. If this error persists for a minute, you can try to disable adblock etc. on this page or site.</p>`;
  });
}

function showErrorsOnReferrers() {
  document.getElementById('referrers-container').outerHTML =
    '<p class="m-5" id="referrers-container">Failed to fetch referrer data. If this error persists for a minute, you can try to disable adblock etc. on this page or site.</p>';
}

function callAnalyticsAPI(date, timeRangeLabel, { organizationId, articleId }) {
  callHistoricalAPI(date, { organizationId, articleId })
    .then((data) => {
      writeCards(data, timeRangeLabel);
      drawCharts(data, timeRangeLabel);
    })
    .catch((_err) => {
      removeCardElements();
      showErrorsOnCharts();
    });

  callReferrersAPI(date, { organizationId, articleId })
    .then((data) => {
      renderReferrers(data);
    })
    .catch((_err) => showErrorsOnReferrers());
}

function drawWeekCharts({ organizationId, articleId }) {
  resetActive(document.getElementById('week-button'));
  const oneWeekAgo = new Date();
  oneWeekAgo.setDate(oneWeekAgo.getDate() - 7);
  callAnalyticsAPI(oneWeekAgo, 'this Week', { organizationId, articleId });
}

function drawMonthCharts({ organizationId, articleId }) {
  resetActive(document.getElementById('month-button'));
  const oneMonthAgo = new Date();
  oneMonthAgo.setMonth(oneMonthAgo.getMonth() - 1);
  callAnalyticsAPI(oneMonthAgo, 'this Month', { organizationId, articleId });
}

function drawInfinityCharts({ organizationId, articleId }) {
  resetActive(document.getElementById('infinity-button'));
  // April 1st is when the DEV analytics feature went into place
  const beginningOfTime = new Date('2019-04-01');
  callAnalyticsAPI(beginningOfTime, '', { organizationId, articleId });
}

export function initCharts({ organizationId, articleId }) {
  const weekButton = document.getElementById('week-button');
  weekButton.addEventListener(
    'click',
    drawWeekCharts.bind(null, { organizationId, articleId }),
  );

  const monthButton = document.getElementById('month-button');
  monthButton.addEventListener(
    'click',
    drawMonthCharts.bind(null, { organizationId, articleId }),
  );

  const infinityButton = document.getElementById('infinity-button');
  infinityButton.addEventListener(
    'click',
    drawInfinityCharts.bind(null, { organizationId, articleId }),
  );

  // draw week charts by default
  drawWeekCharts({ organizationId, articleId });
}