(() => {
  // Theme management
  const themeToggle = document.getElementById("themeToggle");
  const prefersDark = window.matchMedia("(prefers-color-scheme: dark)");

  function getTheme() {
    const saved = localStorage.getItem("theme");
    if (saved) return saved;
    return prefersDark.matches ? "dark" : "light";
  }

  function setTheme(theme) {
    document.documentElement.setAttribute("data-theme", theme);
    localStorage.setItem("theme", theme);
    if (themeToggle) {
      themeToggle.textContent = theme === "dark" ? "☀️ Light Mode" : "🌙 Dark Mode";
    }
  }

  function toggleTheme() {
    const current = document.documentElement.getAttribute("data-theme") || "light";
    setTheme(current === "dark" ? "light" : "dark");
  }

  // Initialize theme
  setTheme(getTheme());

  // Listen for theme toggle
  if (themeToggle) {
    themeToggle.addEventListener("click", toggleTheme);
  }

  // Listen for system theme changes
  prefersDark.addEventListener("change", (e) => {
    if (!localStorage.getItem("theme")) {
      setTheme(e.matches ? "dark" : "light");
    }
  });

  let qs = new URLSearchParams(window.location.search);
  const qInput = document.getElementById("q");
  const channelDropdown = document.getElementById("channelDropdown");
  const channelSummary = document.getElementById("channelSummary");
  const channelOptions = document.getElementById("channelOptions");
  const sortSel = document.getElementById("sort");
  const sizeSel = document.getElementById("size");
  const exactToggle = document.getElementById("exactToggle");
  const fuzzyToggle = document.getElementById("fuzzyToggle");
  const phraseToggle = document.getElementById("phraseToggle");
  const queryToggle = document.getElementById("queryStringToggle");
  const searchBtn = document.getElementById("searchBtn");
  const resultsDiv = document.getElementById("results");
  const metaDiv = document.getElementById("meta");
  const metricsContainer = document.getElementById("metrics");
  const metricsStatus = document.getElementById("metricsStatus");
  const metricsContent = document.getElementById("metricsContent");
  const freqSummary = document.getElementById("frequencySummary");
  const freqChart = document.getElementById("frequencyChart");
  const channelMap = new Map();
  const selectedChannels = new Set();
  let pendingChannelSelection = [];
  let channelsReady = false;
  let suppressChannelChange = false;
  let allChannelsCheckbox = null;
  let previousToggleState = { exact: true, fuzzy: true, phrase: true };
  let currentPage =
    parseInt(qs.get("page") || "0", 10) ||
    0;

  function parseBoolParam(name, defaultValue) {
    const raw = qs.get(name);
    if (raw === null) return defaultValue;
    const lowered = raw.toLowerCase();
    return !["0", "false", "no"].includes(lowered);
  }

  function parseChannelParams(params) {
    const collected = [];
    if (!params) return collected;
    const seen = new Set();
    const rawValues = params.getAll("channel_id");
    const legacy = params.get("channel");
    if (legacy) rawValues.push(legacy);
    rawValues.forEach((value) => {
      if (value == null) return;
      String(value)
        .split(",")
        .map((part) => part.trim())
        .filter((part) => part && part.toLowerCase() !== "all")
        .forEach((part) => {
          if (!seen.has(part)) {
            seen.add(part);
            collected.push(part);
          }
        });
    });
    return collected;
  }

  function getSelectedChannels() {
    return Array.from(selectedChannels);
  }

  function ensureAllCheckboxState() {
    if (allChannelsCheckbox) {
      allChannelsCheckbox.checked = selectedChannels.size === 0;
    }
  }

  function updateChannelSummary() {
    if (!channelSummary) return;
    if (!selectedChannels.size) {
      channelSummary.textContent = "All Channels";
      return;
    }
    const names = Array.from(selectedChannels).map(
      (id) => channelMap.get(id) || id
    );
    if (names.length > 1) {
      names.sort((a, b) => a.localeCompare(b, undefined, { sensitivity: "base" }));
    }
    let label = names.slice(0, 3).join(", ");
    if (names.length > 3) {
      label += ` +${names.length - 3} more`;
    }
    channelSummary.textContent = label;
  }

  function applyChannelSelection(ids, { silent = false } = {}) {
    selectedChannels.clear();
    ids.forEach((id) => selectedChannels.add(id));
    pendingChannelSelection = getSelectedChannels();
    ensureAllCheckboxState();
    if (channelOptions) {
      suppressChannelChange = true;
      const checkboxes = channelOptions.querySelectorAll(
        'input[type="checkbox"][data-channel="1"]'
      );
      checkboxes.forEach((checkbox) => {
        checkbox.checked = selectedChannels.has(checkbox.value);
      });
      suppressChannelChange = false;
    }
    updateChannelSummary();
    if (!silent && channelsReady) {
      runSearch(0);
    }
  }

  function setFromQuery() {
    qInput.value = qs.get("q") || "";
    sortSel.value = qs.get("sort") || "relevant";
    sizeSel.value = qs.get("size") || "10";
    pendingChannelSelection = parseChannelParams(qs);
    applyChannelSelection(pendingChannelSelection, { silent: true });
    exactToggle.checked = parseBoolParam("exact", true);
    fuzzyToggle.checked = parseBoolParam("fuzzy", true);
    phraseToggle.checked = parseBoolParam("phrase", true);
    queryToggle.checked = parseBoolParam("query_string", false);
    applyQueryMode();
    rememberToggleState();
  }

  function applyQueryMode() {
    if (!queryToggle) return;
    if (queryToggle.checked) {
      if (!exactToggle.disabled) {
        previousToggleState = {
          exact: exactToggle.checked,
          fuzzy: fuzzyToggle.checked,
          phrase: phraseToggle.checked,
        };
      }
      exactToggle.checked = false;
      fuzzyToggle.checked = false;
      phraseToggle.checked = false;
      exactToggle.disabled = true;
      fuzzyToggle.disabled = true;
      phraseToggle.disabled = true;
    } else {
      exactToggle.disabled = false;
      fuzzyToggle.disabled = false;
      phraseToggle.disabled = false;
      exactToggle.checked = previousToggleState.exact;
      fuzzyToggle.checked = previousToggleState.fuzzy;
      phraseToggle.checked = previousToggleState.phrase;
    }
  }

  function rememberToggleState() {
    if (queryToggle && !queryToggle.checked) {
      previousToggleState = {
        exact: !!exactToggle.checked,
        fuzzy: !!fuzzyToggle.checked,
        phrase: !!phraseToggle.checked,
      };
    }
  }

  if (channelOptions) {
    channelOptions.addEventListener("change", (event) => {
      const target = event.target;
      if (!(target instanceof HTMLInputElement) || target.type !== "checkbox") {
        return;
      }
      if (suppressChannelChange) {
        return;
      }
      if (target.dataset.all === "1") {
        if (!target.checked && !selectedChannels.size) {
          suppressChannelChange = true;
          target.checked = true;
          suppressChannelChange = false;
          return;
        }
        if (target.checked) {
          selectedChannels.clear();
          pendingChannelSelection = [];
          suppressChannelChange = true;
          const others = channelOptions.querySelectorAll(
            'input[type="checkbox"][data-channel="1"]'
          );
          others.forEach((checkbox) => {
            checkbox.checked = false;
          });
          suppressChannelChange = false;
          ensureAllCheckboxState();
          updateChannelSummary();
          if (channelsReady) {
            runSearch(0);
          }
        }
        return;
      }

      const id = target.value;
      if (!id) return;
      if (target.checked) {
        selectedChannels.add(id);
      } else {
        selectedChannels.delete(id);
      }
      pendingChannelSelection = getSelectedChannels();
      ensureAllCheckboxState();
      updateChannelSummary();
      if (channelsReady) {
        runSearch(0);
      }
    });
  }

  async function loadChannels() {
    if (!channelOptions) {
      channelsReady = true;
      return;
    }
    try {
      const res = await fetch("/api/channels");
      const data = await res.json();
      channelMap.clear();
      channelOptions.innerHTML = "";

      const listFragment = document.createDocumentFragment();

      const allLabel = document.createElement("label");
      allLabel.className = "channel-option";
      allChannelsCheckbox = document.createElement("input");
      allChannelsCheckbox.type = "checkbox";
      allChannelsCheckbox.dataset.all = "1";
      allChannelsCheckbox.checked = selectedChannels.size === 0;
      const allText = document.createElement("span");
      allText.textContent = "All Channels";
      allLabel.appendChild(allChannelsCheckbox);
      allLabel.appendChild(allText);
      listFragment.appendChild(allLabel);

      data.forEach((item) => {
        const label = document.createElement("label");
        label.className = "channel-option";
        const checkbox = document.createElement("input");
        checkbox.type = "checkbox";
        checkbox.value = item.Id;
        checkbox.dataset.channel = "1";
        const text = document.createElement("span");
        text.textContent = `${item.Name} (${item.Count})`;
        label.appendChild(checkbox);
        label.appendChild(text);
        listFragment.appendChild(label);
        channelMap.set(item.Id, item.Name);
      });

      channelOptions.appendChild(listFragment);

      if (!data.length) {
        const empty = document.createElement("div");
        empty.textContent = "No channels available.";
        channelOptions.appendChild(empty);
      }

      const initialSelection = pendingChannelSelection.length
        ? pendingChannelSelection
        : Array.from(selectedChannels);
      applyChannelSelection(initialSelection, { silent: true });
      channelsReady = true;
      updateChannelSummary();
    } catch (err) {
      console.error("Failed to load channels", err);
      channelOptions.innerHTML = "<div>Failed to load channels.</div>";
      channelsReady = true;
      ensureAllCheckboxState();
      updateChannelSummary();
    }
  }

  function updateUrl(q, sort, channels, page, size, exact, fuzzy, phrase, queryMode) {
    const next = new URL(window.location.href);
    next.searchParams.set("q", q);
    next.searchParams.set("sort", sort);
    next.searchParams.delete("channel_id");
    next.searchParams.delete("channel");
    channels.forEach((id) => next.searchParams.append("channel_id", id));
    next.searchParams.set("page", page);
    next.searchParams.set("size", size);
    next.searchParams.set("exact", exact ? "1" : "0");
    next.searchParams.set("fuzzy", fuzzy ? "1" : "0");
    next.searchParams.set("phrase", phrase ? "1" : "0");
    next.searchParams.set("query_string", queryMode ? "1" : "0");
    history.pushState({}, "", next.toString());
  }

  function fmtDate(value) {
    try {
      return (value || "").split("T")[0];
    } catch {
      return value;
    }
  }

  function fmtNumber(n) {
    if (typeof n === "number") return n.toLocaleString();
    return n;
  }

  function formatTimestamp(seconds) {
    if (!seconds && seconds !== 0) return "00:00";
    const hours = Math.floor(seconds / 3600);
    const mins = Math.floor((seconds % 3600) / 60);
    const secs = Math.floor(seconds % 60);

    if (hours > 0) {
      return `${hours}:${mins.toString().padStart(2, '0')}:${secs.toString().padStart(2, '0')}`;
    }
    return `${mins}:${secs.toString().padStart(2, '0')}`;
  }

  function getYouTubeTimestampUrl(baseUrl, seconds) {
    if (!baseUrl) return '#';
    const url = new URL(baseUrl);
    url.searchParams.set('t', Math.floor(seconds) + 's');
    return url.toString();
  }

  function renderTranscriptSegment(segment, videoUrl) {
    const segmentDiv = document.createElement('div');
    segmentDiv.className = 'transcript-segment';
    segmentDiv.dataset.text = (segment.text || '').toLowerCase();

    const startSeconds = segment.start_seconds || segment.start || 0;
    const timestampText = formatTimestamp(startSeconds);
    const timestampUrl = getYouTubeTimestampUrl(videoUrl, startSeconds);

    const timestampLink = document.createElement('a');
    timestampLink.href = timestampUrl;
    timestampLink.className = 'timestamp-link';
    timestampLink.textContent = timestampText;
    timestampLink.target = '_blank';
    timestampLink.rel = 'noopener';

    const textSpan = document.createElement('span');
    textSpan.className = 'transcript-text';
    textSpan.textContent = segment.text || '';

    segmentDiv.appendChild(timestampLink);
    segmentDiv.appendChild(textSpan);

    return segmentDiv;
  }

  function stripHtmlAndNormalize(html) {
    const temp = document.createElement('div');
    temp.innerHTML = html;
    return temp.textContent.trim().toLowerCase().replace(/\s+/g, ' ');
  }

  function extractMarkedText(html) {
    // Extract text from <mark> tags as these are the actual search matches
    const temp = document.createElement('div');
    temp.innerHTML = html;
    const marks = temp.querySelectorAll('mark');
    if (marks.length > 0) {
      return Array.from(marks).map(m => m.textContent.trim().toLowerCase()).join(' ');
    }
    return null;
  }

  function findMatchingSegment(transcriptDiv, searchText) {
    const segments = Array.from(transcriptDiv.querySelectorAll('.transcript-segment'));
    const normalized = searchText.toLowerCase().replace(/\s+/g, ' ').trim();

    // Strategy 1: Try to match the marked/highlighted words first (most reliable)
    const markedText = extractMarkedText(searchText);
    if (markedText) {
      const markedWords = markedText.split(' ').filter(w => w.length > 2);
      let bestMatch = null;
      let bestScore = 0;

      for (const segment of segments) {
        const segmentText = segment.dataset.text;
        if (!segmentText) continue;

        let matchCount = 0;
        for (const word of markedWords) {
          if (segmentText.includes(word)) {
            matchCount++;
          }
        }

        const score = matchCount / markedWords.length;
        if (score > bestScore) {
          bestScore = score;
          bestMatch = segment;
        }
      }

      // If we found a good match with marked words, use it
      if (bestMatch && bestScore >= 0.7) {
        return bestMatch;
      }
    }

    // Strategy 2: Try exact substring match
    for (const segment of segments) {
      const segmentText = segment.dataset.text;
      if (segmentText && segmentText.includes(normalized)) {
        return segment;
      }
    }

    // Strategy 3: Try matching a sliding window of the search text
    // (since highlights may span multiple segments, try smaller chunks)
    const words = normalized.split(' ');
    if (words.length > 10) {
      // Try chunks of 8 consecutive words from the middle (most likely to be in one segment)
      const chunkSize = 8;
      const startIdx = Math.floor((words.length - chunkSize) / 2);
      const chunk = words.slice(startIdx, startIdx + chunkSize).join(' ');

      for (const segment of segments) {
        const segmentText = segment.dataset.text;
        if (segmentText && segmentText.includes(chunk)) {
          return segment;
        }
      }
    }

    // Strategy 4: Fuzzy word matching (at least 50% of words match)
    const searchWords = normalized.split(' ').filter(w => w.length > 2);
    if (searchWords.length === 0) return null;

    // Take up to 15 most distinctive words (skip very common words)
    const commonWords = new Set(['the', 'and', 'that', 'this', 'with', 'for', 'are', 'but', 'not', 'you', 'have', 'from', 'was', 'been', 'has', 'had', 'were']);
    const distinctWords = searchWords
      .filter(w => !commonWords.has(w))
      .slice(0, 15);

    let bestMatch = null;
    let bestScore = 0;

    for (const segment of segments) {
      const segmentText = segment.dataset.text;
      if (!segmentText) continue;

      let matchCount = 0;
      let consecutiveMatches = 0;
      let maxConsecutive = 0;

      for (let i = 0; i < distinctWords.length; i++) {
        if (segmentText.includes(distinctWords[i])) {
          matchCount++;
          consecutiveMatches++;
          maxConsecutive = Math.max(maxConsecutive, consecutiveMatches);
        } else {
          consecutiveMatches = 0;
        }
      }

      // Score considers both match percentage and consecutive matches (phrase matches)
      const matchScore = matchCount / distinctWords.length;
      const consecutiveBonus = maxConsecutive / distinctWords.length * 0.3;
      const score = matchScore + consecutiveBonus;

      if (score > bestScore && score >= 0.4) {
        bestScore = score;
        bestMatch = segment;
      }
    }

    return bestMatch;
  }

  function scrollToSegment(segment) {
    if (!segment) return;

    // Remove any existing focus
    const previousFocused = segment.parentElement.querySelectorAll('.transcript-segment.focused');
    previousFocused.forEach(s => s.classList.remove('focused'));

    // Add focus to this segment
    segment.classList.add('focused');

    // Scroll to it
    segment.scrollIntoView({ behavior: 'smooth', block: 'center' });

    // Remove focus after animation
    setTimeout(() => {
      segment.classList.remove('focused');
    }, 3000);
  }

  async function fetchAndDisplayTranscript(videoId, videoUrl, containerElement, button, highlightText = null) {
    const existingTranscript = containerElement.querySelector('.full-transcript');
    if (existingTranscript && !highlightText) {
      existingTranscript.remove();
      button.textContent = 'View Full Transcript';
      return;
    }

    // If transcript exists and we have highlight text, just scroll to it
    if (existingTranscript && highlightText) {
      const segment = findMatchingSegment(existingTranscript, highlightText);
      if (segment) {
        scrollToSegment(segment);
      }
      return;
    }

    button.disabled = true;
    button.textContent = 'Loading...';

    try {
      const res = await fetch(`/api/transcript?video_id=${encodeURIComponent(videoId)}`);
      if (!res.ok) {
        throw new Error(`Failed to fetch transcript: ${res.status}`);
      }

      const data = await res.json();
      const transcriptDiv = document.createElement('div');
      transcriptDiv.className = 'full-transcript';

      const header = document.createElement('div');
      header.className = 'transcript-header';

      const title = document.createElement('span');
      title.textContent = 'Full Transcript';

      const closeBtn = document.createElement('span');
      closeBtn.className = 'transcript-close';
      closeBtn.textContent = '×';
      closeBtn.title = 'Close transcript';
      closeBtn.onclick = () => {
        transcriptDiv.remove();
        button.textContent = 'View Full Transcript';
        button.disabled = false;
      };

      header.appendChild(title);
      header.appendChild(closeBtn);
      transcriptDiv.appendChild(header);

      const primaryParts = data.transcript_parts || [];
      const secondaryParts = data.transcript_secondary_parts || [];

      if (!primaryParts.length && !secondaryParts.length) {
        const noTranscript = document.createElement('div');
        noTranscript.className = 'muted';
        noTranscript.textContent = 'No transcript available for this video.';
        transcriptDiv.appendChild(noTranscript);
      } else {
        if (primaryParts.length) {
          const primaryHeader = document.createElement('div');
          primaryHeader.style.marginBottom = '8px';
          primaryHeader.style.fontWeight = 'bold';
          primaryHeader.style.fontSize = '12px';
          primaryHeader.style.color = '#666';
          primaryHeader.textContent = 'Primary Transcript';
          transcriptDiv.appendChild(primaryHeader);

          primaryParts.forEach(segment => {
            transcriptDiv.appendChild(renderTranscriptSegment(segment, videoUrl));
          });
        }

        if (secondaryParts.length) {
          const secondaryHeader = document.createElement('div');
          secondaryHeader.style.marginTop = primaryParts.length ? '16px' : '0';
          secondaryHeader.style.marginBottom = '8px';
          secondaryHeader.style.fontWeight = 'bold';
          secondaryHeader.style.fontSize = '12px';
          secondaryHeader.style.color = '#666';
          secondaryHeader.textContent = 'Secondary Transcript';
          transcriptDiv.appendChild(secondaryHeader);

          secondaryParts.forEach(segment => {
            transcriptDiv.appendChild(renderTranscriptSegment(segment, videoUrl));
          });
        }
      }

      containerElement.appendChild(transcriptDiv);
      button.textContent = 'Hide Transcript';
      button.disabled = false;

      // If highlight text provided, scroll to it after a brief delay
      if (highlightText) {
        setTimeout(() => {
          const segment = findMatchingSegment(transcriptDiv, highlightText);
          if (segment) {
            scrollToSegment(segment);
          }
        }, 100);
      }
    } catch (err) {
      console.error('Error fetching transcript:', err);
      button.textContent = 'View Full Transcript';
      button.disabled = false;
      alert('Failed to load transcript. Please try again.');
    }
  }

  function renderMetrics(data) {
  if (!metricsContent) return;
  metricsContent.innerHTML = "";
  if (!data) return;

  if (metricsStatus) {
    metricsStatus.textContent = "";
  }

  const summary = document.createElement("div");
  summary.innerHTML = `<strong>Entries:</strong> ${fmtNumber(data.totalItems)} • <strong>Channels:</strong> ${fmtNumber(data.totalChannels)}`;
  metricsContent.appendChild(summary);

  if (Array.isArray(data.itemsPerChannel) && data.itemsPerChannel.length) {
    const top = data.itemsPerChannel.slice(0, 5);
    const channelHeader = document.createElement("div");
    channelHeader.style.marginTop = "8px";
    channelHeader.innerHTML = "<strong>Top Channels</strong>";
    metricsContent.appendChild(channelHeader);

    const channelList = document.createElement("div");
    channelList.className = "muted";
    top.forEach((entry) => {
      const row = document.createElement("div");
      row.textContent = `${entry.label}: ${fmtNumber(entry.count)}`;
      channelList.appendChild(row);
    });
    metricsContent.appendChild(channelList);
  }
}

async function loadMetrics() {
  if (!metricsContainer) return;
  metricsContainer.dataset.loading = "1";
  if (!metricsContainer.dataset.loaded && metricsStatus) {
    metricsStatus.textContent = "Loading metrics…";
  }
  try {
    const res = await fetch("/api/metrics");
    const data = await res.json();
    renderMetrics(data);
    metricsContainer.dataset.loaded = "1";
  } catch (err) {
    console.error("Failed to load metrics", err);
    if (!metricsContainer.dataset.loaded && metricsStatus) {
      metricsStatus.textContent = "Metrics unavailable.";
    }
  } finally {
    delete metricsContainer.dataset.loading;
  }
}

function clearFrequency(message) {
  if (freqSummary) {
    freqSummary.textContent = message || "";
  }
  if (freqChart) {
    freqChart.innerHTML = "";
  }
}

function renderFrequencyChart(buckets, channelTotals) {
  if (!freqChart || typeof d3 === "undefined") {
    return;
  }
  freqChart.innerHTML = "";
  if (!buckets.length) {
    clearFrequency("No matches for this query.");
    return;
  }

  let channelsOrder =
    (channelTotals && channelTotals.length
      ? channelTotals.map((entry) => entry.id)
      : []) || [];
  if (!channelsOrder.length) {
    const unique = new Set();
    buckets.forEach((bucket) => {
      (bucket.channels || []).forEach((entry) => unique.add(entry.id));
    });
    channelsOrder = Array.from(unique);
  }
  channelsOrder = channelsOrder.slice(0, 6);
  if (!channelsOrder.length) {
    clearFrequency("No matches for this query.");
    return;
  }

  const dateKeyFormat = d3.timeFormat("%Y-%m-%d");
  const parsed = buckets
    .map((bucket) => {
      const parsedDate = d3.isoParse(bucket.date) || new Date(bucket.date);
      if (!(parsedDate instanceof Date) || Number.isNaN(parsedDate.valueOf())) {
        return null;
      }
      const counts = {};
      (bucket.channels || []).forEach((entry) => {
        if (channelsOrder.includes(entry.id)) {
          counts[entry.id] = entry.count || 0;
        }
      });
      return {
        date: parsedDate,
        dateKey: dateKeyFormat(parsedDate),
        counts,
      };
    })
    .filter(Boolean);

  if (!parsed.length) {
    clearFrequency("Timeline unavailable.");
    return;
  }

  const margin = { top: 12, right: 12, bottom: 52, left: 56 };
  const fullWidth = freqChart.clientWidth || 360;
  const fullHeight = 220;
  const width = fullWidth - margin.left - margin.right;
  const height = fullHeight - margin.top - margin.bottom;

  const svg = d3
    .select(freqChart)
    .append("svg")
    .attr("width", fullWidth)
    .attr("height", fullHeight);

  const g = svg
    .append("g")
    .attr("transform", `translate(${margin.left},${margin.top})`);

  const x = d3
    .scaleBand()
    .domain(parsed.map((entry) => entry.dateKey))
    .range([0, width])
    .padding(0.25);

  const yMax = d3.max(parsed, (entry) =>
    d3.sum(channelsOrder, (key) => entry.counts[key] || 0)
  );

  const y = d3
    .scaleLinear()
    .domain([0, yMax || 0])
    .nice()
    .range([height, 0]);

  const tickValues =
    parsed.length <= 6
      ? parsed.map((entry) => entry.dateKey)
      : parsed
          .filter((_, index, arr) => index % Math.ceil(arr.length / 6) === 0)
          .map((entry) => entry.dateKey);

  const xAxis = d3.axisBottom(x).tickValues(tickValues);
  const yAxis = d3.axisLeft(y).ticks(5);

  g.append("g")
    .attr("class", "axis")
    .attr("transform", `translate(0,${height})`)
    .call(xAxis)
    .selectAll("text")
    .attr("text-anchor", "end")
    .attr("transform", "rotate(-35)")
    .attr("dx", "-0.8em")
    .attr("dy", "0.15em");

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

  const stack = d3.stack().keys(channelsOrder).value((entry, key) => entry.counts[key] || 0);
  const stacked = stack(parsed);
  const color = d3.scaleOrdinal(channelsOrder, d3.schemeTableau10);

  const layers = g
    .selectAll(".freq-layer")
    .data(stacked)
    .enter()
    .append("g")
    .attr("class", "freq-layer")
    .attr("fill", (d) => color(d.key));

  layers
    .selectAll("rect")
    .data((d) => d)
    .enter()
    .append("rect")
    .attr("x", (d) => x(d.data.dateKey))
    .attr("width", x.bandwidth())
    .attr("y", (d) => y(d[1]))
    .attr("height", (d) => y(d[0]) - y(d[1]))
    .append("title")
    .text(function (d) {
      const group = this.parentNode ? this.parentNode.parentNode : null;
      const key = group ? d3.select(group).datum().key : undefined;
      const label = key ? channelMap.get(key) || key : key || '';
      return `${dateKeyFormat(d.data.date)}: ${d[1] - d[0]}${label ? " (" + label + ")" : ''}`;
    });

  const legend = document.createElement("div");
  legend.className = "freq-legend";
  channelsOrder.forEach((key) => {
    const item = document.createElement("div");
    item.className = "freq-legend-item";
    const swatch = document.createElement("span");
    swatch.className = "freq-legend-swatch";
    swatch.style.backgroundColor = color(key);
    const label = document.createElement("span");
    label.textContent = channelMap.get(key) || key;
    item.appendChild(swatch);
    item.appendChild(label);
    legend.appendChild(item);
  });
  freqChart.appendChild(legend);
}

async function updateFrequencyChart(term, channels, queryMode) {
  if (!freqChart || typeof d3 === "undefined") {
    return;
  }
  let trimmed = term.trim();
  if (!trimmed) {
    if (queryMode) {
      trimmed = "*";
    } else {
      clearFrequency("Enter a query to see timeline.");
      return;
    }
  }

  const params = new URLSearchParams();
  params.set("term", trimmed);
  params.set("interval", "month");
  (channels || []).forEach((id) => params.append("channel_id", id));
  if (queryMode) {
    params.set("query_string", "1");
  }

  clearFrequency("Loading timeline…");
  try {
    const res = await fetch(`/api/frequency?${params.toString()}`);
    if (!res.ok) {
      throw new Error(`Request failed with status ${res.status}`);
    }
    const payload = await res.json();
    const total = payload.totalResults || 0;
    if (freqSummary) {
      if (total === 0) {
        freqSummary.textContent = "No matches for this query.";
      } else if (queryMode) {
        freqSummary.textContent = `Matches: ${total.toLocaleString()} • Interval: ${payload.interval || "month"} (query-string)`;
      } else {
        freqSummary.textContent = `Matches: ${total.toLocaleString()} • Interval: ${payload.interval || "month"}`;
      }
    }
    if (total === 0) {
      freqChart.innerHTML = "";
      return;
    }
    renderFrequencyChart(payload.buckets || [], payload.channels || []);
  } catch (err) {
    console.error(err);
    clearFrequency("Timeline unavailable.");
  }
}

  function renderResults(payload, page) {
    resultsDiv.innerHTML = "";
    metaDiv.textContent = `Total: ${payload.totalResults} • Page ${
      page + 1
    } of ${payload.totalPages}`;

    (payload.items || []).forEach((item) => {
      const el = document.createElement("div");
      el.className = "item";
      const titleHtml =
        item.titleHtml || escapeHtml(item.title || "Untitled");
      const descriptionHtml =
        item.descriptionHtml || escapeHtml(item.description || "");

      const header = document.createElement("div");
      const badges = [];
      if (item.highlightSource && item.highlightSource.primary) badges.push('primary transcript');
      if (item.highlightSource && item.highlightSource.secondary) badges.push('secondary transcript');
      const badgeHtml = badges.length
        ? `<div class="badge-row">${badges
            .map((b) => `<span class="badge">${escapeHtml(b)}</span>` )
            .join('')}</div>`
        : '';
      header.innerHTML = `
        <strong>${titleHtml}</strong>
        <div class="muted">${escapeHtml(item.channel_name || "")} • ${fmtDate(
        item.date
      )}</div>
        <div class="muted"><a href="${item.url}" target="_blank" rel="noopener">Open on YouTube</a></div>
        ${badgeHtml}
      `;
      el.appendChild(header);

      if (descriptionHtml) {
        const desc = document.createElement("div");
        desc.className = "muted";
        desc.innerHTML = descriptionHtml;
        el.appendChild(desc);
      }

      if (Array.isArray(item.toHighlight) && item.toHighlight.length) {
        const highlights = document.createElement("div");
        highlights.className = "transcript highlight-list";
        item.toHighlight.forEach((entry) => {
          const html = typeof entry === "string" ? entry : entry?.html;
          if (!html) return;
          const row = document.createElement("div");
          row.className = "highlight-row";
          row.innerHTML = html;
          row.title = "Click to jump to this location in the transcript";

          // Make highlight clickable
          row.onclick = () => {
            const transcriptBtn = el.querySelector(".transcript-toggle");
            if (transcriptBtn && item.video_id) {
              const highlightText = stripHtmlAndNormalize(html);
              fetchAndDisplayTranscript(item.video_id, item.url, el, transcriptBtn, highlightText);
            }
          };

          highlights.appendChild(row);
        });
        if (highlights.childElementCount) {
          el.appendChild(highlights);
        }
      }

      if (item.video_id) {
        const transcriptBtn = document.createElement("button");
        transcriptBtn.className = "transcript-toggle";
        transcriptBtn.textContent = "View Full Transcript";
        transcriptBtn.onclick = () => {
          fetchAndDisplayTranscript(item.video_id, item.url, el, transcriptBtn);
        };
        el.appendChild(transcriptBtn);
      }

      resultsDiv.appendChild(el);
    });

    const pager = document.createElement("div");
    pager.className = "pager";
    const prev = document.createElement("button");
    prev.textContent = "Prev";
    prev.disabled = page <= 0;
    const next = document.createElement("button");
    next.textContent = "Next";
    next.disabled = page + 1 >= payload.totalPages;
    prev.onclick = () => runSearch(page - 1);
    next.onclick = () => runSearch(page + 1);
    pager.appendChild(prev);
    pager.appendChild(next);
    resultsDiv.appendChild(pager);
  }

  async function runSearch(pageOverride, pushState = true) {
    const q = qInput.value.trim();
    const channels = getSelectedChannels();
    const sort = sortSel.value;
    const size = parseInt(sizeSel.value, 10) || 10;
    const queryMode = queryToggle && queryToggle.checked;
    let exact = !!exactToggle.checked;
    let fuzzy = !!fuzzyToggle.checked;
    let phrase = !!phraseToggle.checked;
    if (queryMode) {
      exact = false;
      fuzzy = false;
      phrase = false;
    } else {
      previousToggleState = {
        exact,
        fuzzy,
        phrase,
      };
    }
    const page = pageOverride != null ? pageOverride : currentPage;
    currentPage = page;

    if (pushState) {
      updateUrl(q, sort, channels, page, size, exact, fuzzy, phrase, queryMode);
    }

    const params = new URLSearchParams();
    params.set("q", q);
    params.set("sort", sort);
    params.set("size", String(size));
    params.set("page", String(page));
    params.set("exact", exact ? "1" : "0");
    params.set("fuzzy", fuzzy ? "1" : "0");
    params.set("phrase", phrase ? "1" : "0");
    params.set("query_string", queryMode ? "1" : "0");
    channels.forEach((id) => params.append("channel_id", id));

    const res = await fetch(`/api/search?${params.toString()}`);
    const payload = await res.json();
    renderResults(payload, page);
    updateFrequencyChart(q, channels, queryMode);
  }

searchBtn.addEventListener("click", () => runSearch(0));
  qInput.addEventListener("keypress", (e) => {
    if (e.key === "Enter") runSearch(0);
  });
  sortSel.addEventListener("change", () => runSearch(0));
  sizeSel.addEventListener("change", () => runSearch(0));
  exactToggle.addEventListener("change", () => { rememberToggleState(); runSearch(0); });
  fuzzyToggle.addEventListener("change", () => { rememberToggleState(); runSearch(0); });
  phraseToggle.addEventListener("change", () => { rememberToggleState(); runSearch(0); });
  if (queryToggle) {
    queryToggle.addEventListener("change", () => { applyQueryMode(); runSearch(0); });
  }

window.addEventListener("popstate", () => {
    qs = new URLSearchParams(window.location.search);
    setFromQuery();
    currentPage = parseInt(qs.get("page") || "0", 10) || 0;
    runSearch(currentPage, false);
  });

  setFromQuery();
  loadMetrics();
  loadChannels().then(() => runSearch(currentPage));
})();

function escapeHtml(str) {
  return (str || "").replace(/[&<>"']/g, (ch) => {
    switch (ch) {
      case "&":
        return "&amp;";
      case "<":
        return "&lt;";
      case ">":
        return "&gt;";
      case '"':
        return "&quot;";
      case "'":
        return "&#39;";
      default:
        return ch;
    }
  });
}