// ---------------------------------------------------------------
// Activity Time Explorer — fully client-side processing
// ---------------------------------------------------------------

const el = (id) => document.getElementById(id);

// ---- State ----
const state = {
  rows: [],         // parsed CSV rows (array of objects)
  columns: [],      // CSV header column names
  filtered: [],     // filtered subset
  page: 1,
  pageSize: 25,
  sortBy: "Total Duration (s)",
  sortDir: "desc",
  debounceTimer: null,
};

// ---- Elements ----
const fileInput = el("fileInput");
const uploadTile = el("uploadTile");
const fileMeta = el("fileMeta");
const fileMetaName = el("fileMetaName");
const fileMetaRows = el("fileMetaRows");

const searchInput = el("searchInput");
const domainSelect = el("domainSelect");
const reasonSelect = el("reasonSelect");
const startDate = el("startDate");
const endDate = el("endDate");
const minDuration = el("minDuration");
const minDurationLabel = el("minDurationLabel");
const resetBtn = el("resetBtn");
const downloadBtn = el("downloadBtn");

const collapseBtn = el("collapseBtn");
const expandBtn = el("expandBtn");
const sidebar = el("sidebar");

const emptyState = el("emptyState");
const dashboard = el("dashboard");

const tabBtns = document.querySelectorAll(".tab-btn");
const tabDomain = el("tabDomain");
const tabUrl = el("tabUrl");

const toastEl = el("toast");

// ================ Utilities ================

function showToast(msg, isError = false) {
  toastEl.textContent = msg;
  toastEl.classList.toggle("error", isError);
  toastEl.classList.remove("hidden");
  setTimeout(() => toastEl.classList.add("hidden"), 3200);
}

function formatSeconds(sec) {
  sec = Math.round(sec);
  const m = Math.floor(sec / 60);
  const s = sec % 60;
  return m > 0 ? `${m}m ${s}s` : `${s}s`;
}

// ================ CSV Parsing ================

function parseCSV(text) {
  const lines = text.split(/\r?\n/);
  if (lines.length < 2) return { headers: [], rows: [] };

  const headers = parseCSVLine(lines[0]);
  const rows = [];

  for (let i = 1; i < lines.length; i++) {
    const line = lines[i].trim();
    if (!line) continue;
    const values = parseCSVLine(line);
    const row = {};
    headers.forEach((h, idx) => {
      row[h] = values[idx] !== undefined ? values[idx] : "";
    });
    rows.push(row);
  }

  return { headers, rows };
}

function parseCSVLine(line) {
  const result = [];
  let current = "";
  let inQuotes = false;

  for (let i = 0; i < line.length; i++) {
    const ch = line[i];
    if (inQuotes) {
      if (ch === '"') {
        if (i + 1 < line.length && line[i + 1] === '"') {
          current += '"';
          i++;
        } else {
          inQuotes = false;
        }
      } else {
        current += ch;
      }
    } else {
      if (ch === '"') {
        inQuotes = true;
      } else if (ch === ",") {
        result.push(current.trim());
        current = "";
      } else {
        current += ch;
      }
    }
  }
  result.push(current.trim());
  return result;
}

// ================ Data Processing ================

function processRows(rows) {
  return rows.map((row) => {
    // Numeric columns
    for (const col of ["Total Duration (s)", "Idle Time (s)", "Active Time (s)"]) {
      row[col] = parseFloat(row[col]) || 0;
    }

    // Ensure string columns
    for (const col of ["Domain", "URL", "End Reason", "Start Time Local", "End Time Local"]) {
      row[col] = row[col] || "";
    }

    // Extract date from Start Time (UTC)
    if (row["Start Time (UTC)"]) {
      const d = new Date(row["Start Time (UTC)"]);
      row["Date"] = isNaN(d) ? "" : d.toISOString().slice(0, 10);
    } else {
      row["Date"] = "";
    }

    return row;
  });
}

function getUniqueSorted(rows, key) {
  const set = new Set();
  rows.forEach((r) => {
    const val = r[key];
    if (val && val.trim()) set.add(val);
  });
  return Array.from(set).sort();
}

// ================ Sidebar Collapse ================

collapseBtn.addEventListener("click", () => {
  sidebar.classList.add("collapsed");
  expandBtn.classList.remove("hidden");
});
expandBtn.addEventListener("click", () => {
  sidebar.classList.remove("collapsed");
  expandBtn.classList.add("hidden");
});

// ================ File Upload ================

fileInput.addEventListener("change", () => {
  const file = fileInput.files[0];
  if (!file) return;

  const reader = new FileReader();
  reader.onload = (e) => {
    try {
      const { headers, rows } = parseCSV(e.target.result);
      if (!headers.length || !rows.length) {
        showToast("CSV is empty or could not be parsed", true);
        return;
      }
      state.columns = headers;
      state.rows = processRows(rows);
      onDataLoaded(file.name);
    } catch (err) {
      showToast("Error parsing CSV: " + err.message, true);
    }
  };
  reader.onerror = () => showToast("Error reading file", true);
  reader.readAsText(file);
});

function onDataLoaded(filename) {
  const rows = state.rows;

  fileMetaName.textContent = filename;
  fileMetaRows.textContent = `${rows.length.toLocaleString()} rows`;
  fileMeta.classList.remove("hidden");

  // Populate domain select
  domainSelect.innerHTML = "";
  getUniqueSorted(rows, "Domain").forEach((d) => {
    const opt = document.createElement("option");
    opt.value = d;
    opt.textContent = d;
    domainSelect.appendChild(opt);
  });

  // Populate end reason select
  reasonSelect.innerHTML = "";
  getUniqueSorted(rows, "End Reason").forEach((r) => {
    const opt = document.createElement("option");
    opt.value = r;
    opt.textContent = r;
    reasonSelect.appendChild(opt);
  });

  // Date range
  const dates = rows.map((r) => r.Date).filter(Boolean).sort();
  if (dates.length) {
    startDate.min = dates[0];
    startDate.max = dates[dates.length - 1];
    endDate.min = dates[0];
    endDate.max = dates[dates.length - 1];
    startDate.value = dates[0];
    endDate.value = dates[dates.length - 1];
  }

  // Duration slider
  const maxDur = Math.max(...rows.map((r) => r["Total Duration (s)"]), 1);
  minDuration.min = 0;
  minDuration.max = Math.ceil(maxDur);
  minDuration.value = 0;
  minDurationLabel.textContent = "0s";

  // Enable controls
  [searchInput, domainSelect, reasonSelect, startDate, endDate, minDuration, resetBtn, downloadBtn].forEach(
    (elm) => (elm.disabled = false)
  );
  searchInput.value = "";

  emptyState.classList.add("hidden");
  dashboard.classList.remove("hidden");

  showToast(`Loaded ${filename}`);
  state.page = 1;
  runFilter();
}

// ================ Filtering ================

function debounceFilter() {
  clearTimeout(state.debounceTimer);
  state.debounceTimer = setTimeout(() => {
    state.page = 1;
    runFilter();
  }, 300);
}

searchInput.addEventListener("input", debounceFilter);
domainSelect.addEventListener("change", () => { state.page = 1; runFilter(); });
reasonSelect.addEventListener("change", () => { state.page = 1; runFilter(); });
startDate.addEventListener("change", () => { state.page = 1; runFilter(); });
endDate.addEventListener("change", () => { state.page = 1; runFilter(); });
minDuration.addEventListener("input", () => { minDurationLabel.textContent = `${minDuration.value}s`; });
minDuration.addEventListener("change", () => { state.page = 1; runFilter(); });

resetBtn.addEventListener("click", () => {
  searchInput.value = "";
  Array.from(domainSelect.options).forEach((o) => (o.selected = false));
  Array.from(reasonSelect.options).forEach((o) => (o.selected = false));
  startDate.value = startDate.min || "";
  endDate.value = endDate.max || "";
  minDuration.value = 0;
  minDurationLabel.textContent = "0s";
  state.page = 1;
  runFilter();
});

function getSelectedValues(selectEl) {
  return Array.from(selectEl.selectedOptions).map((o) => o.value);
}

function runFilter() {
  if (!state.rows.length) return;

  let filtered = state.rows;

  // Search
  const search = searchInput.value.trim().toLowerCase();
  if (search) {
    filtered = filtered.filter(
      (r) =>
        (r.Domain || "").toLowerCase().includes(search) ||
        (r.URL || "").toLowerCase().includes(search)
    );
  }

  // Domain filter
  const domains = getSelectedValues(domainSelect);
  if (domains.length) {
    const set = new Set(domains);
    filtered = filtered.filter((r) => set.has(r.Domain));
  }

  // End reason filter
  const reasons = getSelectedValues(reasonSelect);
  if (reasons.length) {
    const set = new Set(reasons);
    filtered = filtered.filter((r) => set.has(r["End Reason"]));
  }

  // Date range
  const sd = startDate.value;
  const ed = endDate.value;
  if (sd && ed) {
    filtered = filtered.filter((r) => r.Date >= sd && r.Date <= ed);
  }

  // Min duration
  const minDur = Number(minDuration.value) || 0;
  if (minDur > 0) {
    filtered = filtered.filter((r) => r["Total Duration (s)"] >= minDur);
  }

  state.filtered = filtered;

  renderSummary(filtered);
  renderDomainChart(filtered);
  renderUrlChart(filtered);
  renderTable(filtered);
}

// ================ Summary ================

function renderSummary(filtered) {
  const totalSec = filtered.reduce((s, r) => s + r["Total Duration (s)"], 0);
  const uniqueDomains = new Set(filtered.map((r) => r.Domain)).size;
  const uniqueUrls = new Set(filtered.map((r) => r.URL)).size;

  el("metricEntries").textContent = filtered.length.toLocaleString();
  el("metricTime").textContent = formatSeconds(totalSec);
  el("metricDomains").textContent = uniqueDomains.toLocaleString();
  el("metricUrls").textContent = uniqueUrls.toLocaleString();
}

// ================ Charts ================

function aggregateBy(rows, key, top = 25) {
  const map = {};
  rows.forEach((r) => {
    const k = r[key] || "(empty)";
    map[k] = (map[k] || 0) + r["Total Duration (s)"];
  });
  return Object.entries(map)
    .sort((a, b) => b[1] - a[1])
    .slice(0, top)
    .map(([label, seconds]) => ({ label, seconds }));
}

function renderBarChart(container, items) {
  container.innerHTML = "";
  if (!items.length) return;

  const maxVal = Math.max(...items.map((d) => d.seconds), 1);

  items.forEach((item) => {
    const row = document.createElement("div");
    row.className = "bar-row";

    const label = document.createElement("div");
    label.className = "bar-label";
    label.textContent = item.label;
    label.title = item.label;

    const track = document.createElement("div");
    track.className = "bar-track";
    const fill = document.createElement("div");
    fill.className = "bar-fill";
    fill.style.width = `${(item.seconds / maxVal) * 100}%`;
    track.appendChild(fill);

    const value = document.createElement("div");
    value.className = "bar-value";
    value.textContent = formatSeconds(item.seconds);

    row.appendChild(label);
    row.appendChild(track);
    row.appendChild(value);
    container.appendChild(row);
  });
}

function renderDomainChart(filtered) {
  const chartEl = el("domainChart");
  const emptyEl = el("domainEmpty");
  const items = aggregateBy(filtered, "Domain");
  if (!items.length) {
    chartEl.innerHTML = "";
    emptyEl.classList.remove("hidden");
    return;
  }
  emptyEl.classList.add("hidden");
  renderBarChart(chartEl, items);
}

function renderUrlChart(filtered) {
  const chartEl = el("urlChart");
  const emptyEl = el("urlEmpty");
  const items = aggregateBy(filtered, "URL");
  if (!items.length) {
    chartEl.innerHTML = "";
    emptyEl.classList.remove("hidden");
    return;
  }
  emptyEl.classList.add("hidden");
  renderBarChart(chartEl, items);
}

// ================ Tabs ================

tabBtns.forEach((btn) => {
  btn.addEventListener("click", () => {
    tabBtns.forEach((b) => b.classList.remove("active"));
    btn.classList.add("active");
    if (btn.dataset.tab === "domain") {
      tabDomain.classList.remove("hidden");
      tabUrl.classList.add("hidden");
    } else {
      tabUrl.classList.remove("hidden");
      tabDomain.classList.add("hidden");
    }
  });
});

// ================ Table ================

const displayCols = [
  "Domain",
  "URL",
  "Start Time Local",
  "End Time Local",
  "Total Duration (s)",
  "Idle Time (s)",
  "Active Time (s)",
  "End Reason",
];

function renderTable(filtered) {
  const cols = displayCols.filter((c) => state.columns.includes(c));

  // Sort
  const sorted = [...filtered].sort((a, b) => {
    let va = a[state.sortBy];
    let vb = b[state.sortBy];
    if (typeof va === "number" && typeof vb === "number") {
      return state.sortDir === "asc" ? va - vb : vb - va;
    }
    va = String(va || "");
    vb = String(vb || "");
    return state.sortDir === "asc" ? va.localeCompare(vb) : vb.localeCompare(va);
  });

  // Paginate
  const totalRows = sorted.length;
  const startIdx = (state.page - 1) * state.pageSize;
  const pageRows = sorted.slice(startIdx, startIdx + state.pageSize);

  // Header
  const thead = el("tableHead");
  thead.innerHTML = "";
  const headRow = document.createElement("tr");
  cols.forEach((col) => {
    const th = document.createElement("th");
    th.textContent = col;
    if (state.sortBy === col) {
      const indicator = document.createElement("span");
      indicator.className = "sort-indicator";
      indicator.textContent = state.sortDir === "asc" ? "▲" : "▼";
      th.appendChild(indicator);
    }
    th.addEventListener("click", () => {
      if (state.sortBy === col) {
        state.sortDir = state.sortDir === "asc" ? "desc" : "asc";
      } else {
        state.sortBy = col;
        state.sortDir = "desc";
      }
      state.page = 1;
      runFilter();
    });
    headRow.appendChild(th);
  });
  thead.appendChild(headRow);

  // Body
  const tbody = el("tableBody");
  tbody.innerHTML = "";
  if (!pageRows.length) {
    const tr = document.createElement("tr");
    const td = document.createElement("td");
    td.colSpan = cols.length;
    td.textContent = "No data matches the current filters.";
    td.style.textAlign = "center";
    td.style.color = "var(--text-muted)";
    td.style.padding = "24px";
    tr.appendChild(td);
    tbody.appendChild(tr);
  } else {
    pageRows.forEach((row) => {
      const tr = document.createElement("tr");
      cols.forEach((col) => {
        const td = document.createElement("td");
        let val = row[col];
        if (typeof val === "number" && col.includes("(s)")) val = val.toFixed(1);
        td.textContent = val === null || val === undefined ? "" : val;
        td.title = td.textContent;
        tr.appendChild(td);
      });
      tbody.appendChild(tr);
    });
  }

  renderPagination(totalRows);
}

function renderPagination(totalRows) {
  const container = el("pagination");
  container.innerHTML = "";
  const totalPages = Math.max(Math.ceil(totalRows / state.pageSize), 1);

  const info = document.createElement("span");
  const startIdx = totalRows === 0 ? 0 : (state.page - 1) * state.pageSize + 1;
  const endIdx = Math.min(state.page * state.pageSize, totalRows);
  info.textContent = `${startIdx}–${endIdx} of ${totalRows.toLocaleString()}`;

  const prevBtn = document.createElement("button");
  prevBtn.textContent = "← Prev";
  prevBtn.disabled = state.page <= 1;
  prevBtn.addEventListener("click", () => { state.page--; runFilter(); });

  const nextBtn = document.createElement("button");
  nextBtn.textContent = "Next →";
  nextBtn.disabled = state.page >= totalPages;
  nextBtn.addEventListener("click", () => { state.page++; runFilter(); });

  container.appendChild(info);
  container.appendChild(prevBtn);
  container.appendChild(nextBtn);
}

// ================ Download ================

downloadBtn.addEventListener("click", () => {
  if (!state.filtered.length) return;

  const cols = displayCols.filter((c) => state.columns.includes(c));

  // Sort same as table
  const sorted = [...state.filtered].sort((a, b) => {
    let va = a[state.sortBy];
    let vb = b[state.sortBy];
    if (typeof va === "number" && typeof vb === "number") {
      return state.sortDir === "asc" ? va - vb : vb - va;
    }
    va = String(va || "");
    vb = String(vb || "");
    return state.sortDir === "asc" ? va.localeCompare(vb) : vb.localeCompare(va);
  });

  // Build CSV
  const escapeCSV = (v) => {
    const s = String(v ?? "");
    return s.includes(",") || s.includes('"') || s.includes("\n")
      ? '"' + s.replace(/"/g, '""') + '"'
      : s;
  };

  const lines = [cols.map(escapeCSV).join(",")];
  sorted.forEach((row) => {
    lines.push(cols.map((c) => escapeCSV(row[c])).join(","));
  });

  const blob = new Blob([lines.join("\n")], { type: "text/csv" });
  const url = URL.createObjectURL(blob);
  const a = document.createElement("a");
  a.href = url;
  a.download = "filtered_activity.csv";
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
  URL.revokeObjectURL(url);
});