let allRegions = [];
let currentSort = { column: null, direction: "asc" };

// Dark Mode Toggle
function toggleDarkMode() {
  const html = document.documentElement;
  const sunIcon = document.getElementById("theme-icon-sun");
  const moonIcon = document.getElementById("theme-icon-moon");

  if (html.classList.contains("dark")) {
    html.classList.remove("dark");
    html.classList.add("light");
    sunIcon.classList.add("hidden");
    moonIcon.classList.remove("hidden");
    localStorage.setItem("theme", "light");
  } else {
    html.classList.remove("light");
    html.classList.add("dark");
    sunIcon.classList.remove("hidden");
    moonIcon.classList.add("hidden");
    localStorage.setItem("theme", "dark");
  }
}

// Initialize theme from localStorage
(function initTheme() {
  const savedTheme = localStorage.getItem("theme") || "light";
  const html = document.documentElement;
  const sunIcon = document.getElementById("theme-icon-sun");
  const moonIcon = document.getElementById("theme-icon-moon");

  if (savedTheme === "dark") {
    html.classList.remove("light");
    html.classList.add("dark");
    if (sunIcon) sunIcon.classList.remove("hidden");
    if (moonIcon) moonIcon.classList.add("hidden");
  } else {
    html.classList.remove("dark");
    html.classList.add("light");
    if (sunIcon) sunIcon.classList.add("hidden");
    if (moonIcon) moonIcon.classList.remove("hidden");
  }
})();

// Parse Logic
function parseMemory() {
  const input = document.getElementById("input").value;
  if (!input.trim()) return;

  const lines = input.split("\n");
  const regions = [];
  let currentRegion = null;

  // Updated Regex to be more robust
  // Captures: 1: Start, 2: End, 3: Perms, 4: Name (optional)
  const regionRegex =
    /\[(0x[0-9a-fA-F]+)-(0x[0-9a-fA-F]+)\)\s+([r\-][w\-][x\-][s\-]?)(?:\s+(.*))?/i;
  const dirtyRegex = /Dirty pages:\s+(.+)/i;

  for (let line of lines) {
    line = line.trim();
    if (!line) continue;

    const regionMatch = line.match(regionRegex);
    if (regionMatch) {
      const start = regionMatch[1];
      const end = regionMatch[2];
      const perms = regionMatch[3];
      const name = regionMatch[4] || "";

      currentRegion = {
        startStr: start, // Keep string for display
        endStr: end, // Keep string for display
        startBig: BigInt(start), // Use BigInt for calculation
        endBig: BigInt(end), // Use BigInt for calculation
        perms,
        name,
        dirtyPages: [],
        dirtyCount: 0,
      };

      // Calculate size safely using BigInt
      currentRegion.size = currentRegion.endBig - currentRegion.startBig;

      regions.push(currentRegion);
    } else if (currentRegion) {
      // Check for metadata lines associated with the previous region
      const dirtyMatch = line.match(dirtyRegex);
      if (dirtyMatch) {
        const pages = dirtyMatch[1].split(",").map((p) => p.trim());
        currentRegion.dirtyPages = pages;
        currentRegion.dirtyCount = pages.length;
      }
    }
  }

  allRegions = regions;
  updateStats(regions);
  document.getElementById("stats").classList.remove("hidden");
  document.getElementById("stats").classList.add("grid");
  document.getElementById("filter-section").classList.remove("hidden");
  document.getElementById("filter-section").classList.add("flex");

  // Set default sort to Start Address Ascending
  sortBy("start");
}

function updateStats(regions) {
  const container = document.getElementById("stats");

  const totalRegions = regions.length;
  const totalDirty = regions.reduce((acc, r) => acc + r.dirtyCount, 0);

  // BigInt total size summation
  let totalSizeBytes = 0n;
  regions.forEach((r) => (totalSizeBytes += r.size));

  const execCount = regions.filter((r) => r.perms.includes("x")).length;
  const writeCount = regions.filter((r) => r.perms.includes("w")).length;

  const createCard = (label, value, colorClass) => `
        <div class="bg-white dark:bg-slate-700 p-4 rounded-lg border border-slate-200 dark:border-slate-600 shadow-sm hover:shadow-md transition-shadow">
            <div class="text-xs font-bold text-slate-400 dark:text-slate-500 uppercase tracking-wider mb-1">${label}</div>
            <div class="text-xl md:text-2xl font-bold ${colorClass}">${value}</div>
        </div>
    `;

  container.innerHTML =
    createCard(
      "Total Regions",
      totalRegions,
      "text-slate-800 dark:text-slate-200",
    ) +
    createCard(
      "Total Size",
      formatBytes(totalSizeBytes),
      "text-indigo-600 dark:text-indigo-400",
    ) +
    createCard("Executable", execCount, "text-red-500 dark:text-red-400") +
    createCard("Writable", writeCount, "text-amber-500 dark:text-amber-400") +
    createCard(
      "Dirty Pages",
      totalDirty,
      "text-emerald-600 dark:text-emerald-400",
    );
}

function renderTable(regions) {
  const tbody = document.getElementById("table-body");
  const footer = document.getElementById("footer-count");

  if (regions.length === 0) {
    tbody.innerHTML = `<tr><td colspan="6" class="py-8 text-center text-slate-400">No matching regions found.</td></tr>`;
    footer.textContent = "0 rows";
    return;
  }

  // Limit rendering for performance if massive (simple virtualization cap)
  const renderLimit = 2000;
  const dataset = regions.slice(0, renderLimit);

  const html = dataset
    .map((r) => {
      const isExecutable = r.perms.includes("x");
      const isWritable = r.perms.includes("w");
      const isReadable = r.perms.includes("r");

      // Badges for perms
      let permBadges = "";
      if (isReadable)
        permBadges += `<span class="inline-flex items-center px-1.5 py-0.5 rounded text-xs font-medium bg-green-100 dark:bg-green-900 text-green-800 dark:text-green-200 mr-1">R</span>`;
      else
        permBadges += `<span class="inline-flex items-center px-1.5 py-0.5 rounded text-xs font-medium bg-slate-100 dark:bg-slate-700 text-slate-400 dark:text-slate-500 mr-1">-</span>`;

      if (isWritable)
        permBadges += `<span class="inline-flex items-center px-1.5 py-0.5 rounded text-xs font-medium bg-amber-100 dark:bg-amber-900 text-amber-800 dark:text-amber-200 mr-1">W</span>`;
      else
        permBadges += `<span class="inline-flex items-center px-1.5 py-0.5 rounded text-xs font-medium bg-slate-100 dark:bg-slate-700 text-slate-400 dark:text-slate-500 mr-1">-</span>`;

      if (isExecutable)
        permBadges += `<span class="inline-flex items-center px-1.5 py-0.5 rounded text-xs font-medium bg-red-100 dark:bg-red-900 text-red-800 dark:text-red-200">X</span>`;
      else
        permBadges += `<span class="inline-flex items-center px-1.5 py-0.5 rounded text-xs font-medium bg-slate-100 dark:bg-slate-700 text-slate-400 dark:text-slate-500">-</span>`;

      // Row highlighting
      const rowClass =
        r.dirtyCount > 0
          ? "bg-orange-50 dark:bg-orange-900/20 hover:bg-orange-100 dark:hover:bg-orange-900/30"
          : "hover:bg-slate-50 dark:hover:bg-slate-700";

      return `
            <tr class="${rowClass} transition-colors border-b border-slate-100 dark:border-slate-700 last:border-0">
                <td class="px-6 py-3 whitespace-nowrap font-mono text-xs text-slate-600 dark:text-slate-400 select-all">${r.startStr}</td>
                <td class="px-6 py-3 whitespace-nowrap font-mono text-xs text-slate-600 dark:text-slate-400 select-all">${r.endStr}</td>
                <td class="px-6 py-3 whitespace-nowrap text-sm text-slate-700 dark:text-slate-300 font-medium" title="${r.size.toString()} bytes">${formatBytes(r.size)}</td>
                <td class="px-6 py-3 whitespace-nowrap text-sm">${permBadges}</td>
                <td class="px-6 py-3 text-sm text-slate-700 dark:text-slate-300 break-all max-w-xs">${r.name || '<span class="text-slate-300 dark:text-slate-600 italic">unnamed</span>'}</td>
                <td class="px-6 py-3 whitespace-nowrap text-sm">
                    ${
                      r.dirtyCount > 0
                        ? `<span class="px-2 py-1 text-xs font-bold leading-none text-orange-800 dark:text-orange-200 bg-orange-200 dark:bg-orange-900/50 rounded-full">${r.dirtyCount}</span>`
                        : '<span class="text-slate-300 dark:text-slate-600 text-xs">-</span>'
                    }
                </td>
            </tr>
        `;
    })
    .join("");

  tbody.innerHTML = html;

  const remaining = regions.length - renderLimit;
  footer.innerHTML =
    remaining > 0
      ? `${dataset.length} rows shown (${remaining} hidden for performance)`
      : `${dataset.length} rows`;
}

// --- Helpers & Utilities ---

function formatBytes(bigIntBytes) {
  if (bigIntBytes === 0n) return "0 B";

  // Convert to Number for display formatting (precision loss at PB scale is acceptable for UI)
  const bytes = Number(bigIntBytes);
  const k = 1024;
  const sizes = ["B", "KB", "MB", "GB", "TB", "PB"];
  const i = Math.floor(Math.log(bytes) / Math.log(k));

  return parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + " " + sizes[i];
}

function sortBy(column) {
  if (currentSort.column === column) {
    currentSort.direction = currentSort.direction === "asc" ? "desc" : "asc";
  } else {
    currentSort.column = column;
    currentSort.direction = "asc";
  }

  // Visual indicator helper
  document
    .querySelectorAll(".sort-icon")
    .forEach((el) => (el.textContent = "⇅"));
  document
    .querySelectorAll(".sort-icon")
    .forEach((el) => el.classList.remove("text-indigo-600"));

  // Update active header
  const headers = document.querySelectorAll("th");
  headers.forEach((th) => {
    if (th.onclick.toString().includes(column)) {
      const icon = th.querySelector(".sort-icon");
      icon.textContent = currentSort.direction === "asc" ? "▲" : "▼";
      icon.classList.add("text-indigo-600");
      icon.classList.remove("invisible");
    }
  });

  applyFilters();
}

function applyFilters() {
  const addrFilter = document
    .getElementById("addressFilter")
    .value.toLowerCase();
  const permsFilter = document.getElementById("permsFilter").value;
  const dirtyFilter = document.getElementById("dirtyFilter").value;
  const hideEmpty = document.getElementById("hideEmptyRegions").checked;

  let filtered = allRegions.filter((r) => {
    // 1. Empty/Permissions check
    if (hideEmpty && r.perms.startsWith("---")) return false;

    // 2. Address/Name Search
    if (addrFilter) {
      const searchStr = (r.startStr + r.endStr + r.name).toLowerCase();
      if (!searchStr.includes(addrFilter)) return false;
    }

    // 3. Permissions Dropdown
    if (permsFilter) {
      if (
        permsFilter === "rw" &&
        (!r.perms.includes("r") || !r.perms.includes("w"))
      )
        return false;
      else if (
        permsFilter === "rx" &&
        (!r.perms.includes("r") || !r.perms.includes("x"))
      )
        return false;
      else if (permsFilter.length === 1 && !r.perms.includes(permsFilter))
        return false;
    }

    // 4. Dirty Pages
    if (dirtyFilter === "dirty" && r.dirtyCount === 0) return false;
    if (dirtyFilter === "clean" && r.dirtyCount > 0) return false;

    return true;
  });

  // Apply Sort
  filtered.sort((a, b) => {
    let valA, valB;

    switch (currentSort.column) {
      case "start":
        valA = a.startBig;
        valB = b.startBig;
        break;
      case "end":
        valA = a.endBig;
        valB = b.endBig;
        break;
      case "size":
        valA = a.size;
        valB = b.size;
        break;
      case "perms":
        valA = a.perms;
        valB = b.perms;
        break; // string comparison
      case "name":
        valA = a.name.toLowerCase();
        valB = b.name.toLowerCase();
        break;
      case "dirty":
        valA = a.dirtyCount;
        valB = b.dirtyCount;
        break;
    }

    if (valA < valB) return currentSort.direction === "asc" ? -1 : 1;
    if (valA > valB) return currentSort.direction === "asc" ? 1 : -1;
    return 0;
  });

  renderTable(filtered);
}

function clearAll() {
  document.getElementById("input").value = "";
  document.getElementById("table-body").innerHTML =
    `<tr><td colspan="6" class="py-12 text-center text-slate-400">Waiting for input...</td></tr>`;
  document.getElementById("stats").classList.add("hidden");
  document.getElementById("stats").classList.remove("grid");
  document.getElementById("filter-section").classList.add("hidden");
  document.getElementById("filter-section").classList.remove("flex");
  document.getElementById("footer-count").innerText = "0 rows";

  // Reset filters
  document.getElementById("addressFilter").value = "";
  document.getElementById("permsFilter").value = "";
  document.getElementById("dirtyFilter").value = "";

  allRegions = [];
  currentSort = { column: null, direction: "asc" };
}