const state = {
  adm1: "",
  adm2: "",
  adm3: "",
};

const elements = {
  adm1: document.getElementById("adm1Select"),
  adm2: document.getElementById("adm2Select"),
  adm3: document.getElementById("adm3Select"),
  tableBody: document.getElementById("featureTable"),
  totalAreaRai: document.getElementById("totalAreaRai"),
  itemCount: document.getElementById("itemCount"),
  averageAreaRai: document.getElementById("averageAreaRai"),
  loadingOverlay: document.getElementById("loadingOverlay"),
  clearButton: document.getElementById("clearFilters"),
};

declareLoadingRow("Loading data...");
setLoading(true);

let allFeatures = [];
let map;
let layerControl;
let adminLayer;
let palmLayer;
let layerLookup = new Map();
let activeFeatureId = null;
let activeRowId = null;

initMap();
loadData();
attachEventListeners();

function declareLoadingRow(message) {
  elements.tableBody.innerHTML = `<tr><td colspan="6">${message}</td></tr>`;
}

function initMap() {
  map = L.map("map", {
    preferCanvas: true,
    zoomControl: true,
  });


  const osm = L.tileLayer("https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png", {
    maxZoom: 19,
    attribution: "© OpenStreetMap contributors",
  }).addTo(map);

  const googleHybrid = L.tileLayer(
    "https://{s}.google.com/vt/lyrs=y&x={x}&y={y}&z={z}",
    {
      maxZoom: 21,
      subdomains: ["mt0", "mt1", "mt2", "mt3"],
      attribution: "© Google",
    }
  );

  layerControl = L.control.layers(
    {
      "OpenStreetMap": osm,
      "Google Hybrid": googleHybrid,
    },
    {},
    { collapsed: false }
  ).addTo(map);
  if (L.control && typeof L.control.measure === "function") {
    L.control
      .measure({
        position: "topleft",
        primaryLengthUnit: "kilometers",
        secondaryLengthUnit: "meters",
        primaryAreaUnit: "hectares",
        secondaryAreaUnit: "sqmeters",
      })
      .addTo(map);
  } else {
    console.warn("Leaflet measure plugin is unavailable; measure control disabled.");
  }

  window.addEventListener("resize", () => map.invalidateSize());

  map.createPane("adminPane");
  map.createPane("palmPane");
  map.getPane("adminPane").style.zIndex = 410;
  map.getPane("palmPane").style.zIndex = 420;

  adminLayer = L.geoJSON(null, {
    pane: "adminPane",
    style: {
      color: "#ffbf00ff",
      weight: 0.8,
      fillOpacity: 0,
    },
  }).addTo(map);

  palmLayer = L.geoJSON(null, {
    pane: "palmPane",
    style: palmDefaultStyle,
    onEachFeature: onPalmFeature,
  }).addTo(map);

  layerControl.addOverlay(adminLayer, "Administrative Boundaries");
  layerControl.addOverlay(palmLayer, "Palm Predictions");
}

async function loadData() {
  try {
    setLoading(true);
    const [palmResponse, adminResponse] = await Promise.all([
      fetch("palm_pred_all_admin.geojson"),
      fetch("admin_bnd.geojson"),
    ]);

    if (!palmResponse.ok || !adminResponse.ok) {
      throw new Error("Unable to load GeoJSON files.");
    }

    const [palmData, adminData] = await Promise.all([
      palmResponse.json(),
      adminResponse.json(),
    ]);

    allFeatures = palmData.features;
    adminLayer.addData(adminData);

    initializeSelects();
    updateDashboard({ fitBounds: true });
    setLoading(false);
  } catch (error) {
    console.error(error);
    declareLoadingRow("Failed to load data. Check console for details.");
    setLoading(false);
  }
}

function attachEventListeners() {
  elements.adm1.addEventListener("change", () => {
    state.adm1 = elements.adm1.value;
    state.adm2 = "";
    state.adm3 = "";

    const baseForAdm2 = state.adm1
      ? allFeatures.filter((feature) => feature.properties.ADM1_TH === state.adm1)
      : allFeatures;

    const baseForAdm3 = state.adm1 ? baseForAdm2 : allFeatures;

    populateSelect(elements.adm2, baseForAdm2, "ADM2_TH", Boolean(baseForAdm2.length));
    populateSelect(elements.adm3, baseForAdm3, "ADM3_TH", Boolean(baseForAdm3.length));

    updateDashboard({ fitBounds: true });
  });

  elements.adm2.addEventListener("change", () => {
    state.adm2 = elements.adm2.value;
    state.adm3 = "";

    const baseForAdm3 = allFeatures.filter((feature) => {
      if (state.adm1 && feature.properties.ADM1_TH !== state.adm1) return false;
      if (state.adm2 && feature.properties.ADM2_TH !== state.adm2) return false;
      return true;
    });

    populateSelect(elements.adm3, baseForAdm3, "ADM3_TH", Boolean(baseForAdm3.length));

    updateDashboard({ fitBounds: true });
  });

  elements.adm3.addEventListener("change", () => {
    state.adm3 = elements.adm3.value;
    updateDashboard({ fitBounds: true });
  });

  if (elements.clearButton) {
    elements.clearButton.addEventListener("click", () => {
      state.adm1 = "";
      state.adm2 = "";
      state.adm3 = "";

      elements.adm1.value = "";
      elements.adm2.value = "";
      elements.adm3.value = "";

      elements.adm2.disabled = elements.adm2.options.length <= 1;
      elements.adm3.disabled = elements.adm3.options.length <= 1;

      updateDashboard({ fitBounds: true });
    });
  }
}

function initializeSelects() {
  populateSelect(elements.adm1, allFeatures, "ADM1_TH", Boolean(allFeatures.length));
  populateSelect(elements.adm2, allFeatures, "ADM2_TH", Boolean(allFeatures.length));
  populateSelect(elements.adm3, allFeatures, "ADM3_TH", Boolean(allFeatures.length));
}

function populateSelect(select, features, propertyKey, enable) {
  const selectedValue = select.value;
  const values = getUniqueValues(features, propertyKey);

  select.innerHTML = "";
  const defaultOption = document.createElement("option");
  defaultOption.value = "";
  defaultOption.textContent = "ทั้งหมด";
  select.appendChild(defaultOption);

  values
    .sort((a, b) => a.localeCompare(b, "th", { sensitivity: "base" }))
    .forEach((value) => {
      const option = document.createElement("option");
      option.value = value;
      option.textContent = value;
      select.appendChild(option);
    });

  select.disabled = !enable || values.length === 0;
  if (!select.disabled && values.includes(selectedValue)) {
    select.value = selectedValue;
  } else {
    select.value = "";
  }
}

function getUniqueValues(features, propertyKey) {
  const set = new Set();
  features.forEach((feature) => {
    const value = feature.properties[propertyKey];
    if (value || value === 0) {
      set.add(value);
    }
  });
  return Array.from(set);
}

function applyFilters(features) {
  return features.filter((feature) => {
    const { ADM1_TH, ADM2_TH, ADM3_TH } = feature.properties;
    if (state.adm1 && ADM1_TH !== state.adm1) return false;
    if (state.adm2 && ADM2_TH !== state.adm2) return false;
    if (state.adm3 && ADM3_TH !== state.adm3) return false;
    return true;
  });
}

function updateDashboard({ fitBounds } = { fitBounds: false }) {
  if (!allFeatures.length) return;
  const filtered = applyFilters(allFeatures);

  updateSummary(filtered);
  updatePalmLayer(filtered, { fitBounds });
  renderTable(filtered);
}

function updateSummary(features) {
  const totals = features.reduce(
    (acc, feature) => {
      const { area_rai } = feature.properties;
      acc.area_rai += Number(area_rai) || 0;
      return acc;
    },
    { area_rai: 0 }
  );

  const totalAreaRai = totals.area_rai;
  const count = features.length;
  const averageAreaRai = count ? totalAreaRai / count : 0;

  elements.totalAreaRai.textContent = formatNumber(totalAreaRai, 2);
  elements.itemCount.textContent = formatNumber(count, 0);
  elements.averageAreaRai.textContent = formatNumber(averageAreaRai, 2);
}

function renderTable(features) {
  elements.tableBody.innerHTML = "";
  activeRowId = null;

  if (!features.length) {
    declareLoadingRow("No features match the selected filters.");
    return;
  }

  const fragment = document.createDocumentFragment();

  features.forEach((feature) => {
    const { id, ADM1_TH, ADM2_TH, ADM3_TH, area_m2, area_rai } = feature.properties;
    const row = document.createElement("tr");
    row.dataset.featureId = id;

    row.innerHTML = `
      <td>${id}</td>
      <td>${ADM1_TH || "-"}</td>
      <td>${ADM2_TH || "-"}</td>
      <td>${ADM3_TH || "-"}</td>
      <td>${formatNumber(area_m2, 2)}</td>
      <td>${formatNumber(area_rai, 2)}</td>
    `;

    row.addEventListener("click", () => {
      setActiveRow(id);
      highlightMapFeature(id, { adjustView: true, openPopup: true });
    });

    fragment.appendChild(row);
  });

  elements.tableBody.appendChild(fragment);

  // Highlight the first feature by default for quick context.
  const firstId = features[0].properties.id;
  setActiveRow(firstId);
  highlightMapFeature(firstId, { adjustView: false, openPopup: false });
}

function palmDefaultStyle() {
  return {
    color: "#ffffffff",
    weight: 0.6,
    fillColor: "#649e66ff",
    fillOpacity: 0.7,
  };
}

function palmHighlightStyle() {
  return {
    color: "#ff8800",
    weight: 1.2,
    fillColor: "#ffe0b2",
    fillOpacity: 0.65,
  };
}

function onPalmFeature(feature, layer) {
  const { id } = feature.properties;
  layerLookup.set(id, layer);

  const popupHtml = buildPopupContent(feature.properties);
  layer.bindPopup(popupHtml);

  layer.on("click", () => {
    setActiveRow(id);
    highlightMapFeature(id, { adjustView: false, openPopup: false });
    layer.openPopup();
  });
}

function updatePalmLayer(features, { fitBounds }) {
  layerLookup.clear();
  palmLayer.clearLayers();
  activeFeatureId = null;

  if (!features.length) {
    return;
  }

  palmLayer.addData(features);

  if (fitBounds) {
    const bounds = palmLayer.getBounds();
    if (bounds.isValid()) {
      map.fitBounds(bounds, { padding: [20, 20] });
    }
  }
}

function highlightMapFeature(id, { adjustView = false, openPopup = false } = {}) {
  if (activeFeatureId && layerLookup.has(activeFeatureId)) {
    const previousLayer = layerLookup.get(activeFeatureId);
    palmLayer.resetStyle(previousLayer);
    previousLayer.closePopup();
  }

  activeFeatureId = null;

  const layer = layerLookup.get(id);
  if (!layer) return;

  activeFeatureId = id;
  layer.setStyle(palmHighlightStyle());
  layer.bringToFront();

  if (adjustView) {
    const bounds = layer.getBounds();
    if (bounds.isValid()) {
      map.fitBounds(bounds, { maxZoom: 16, padding: [20, 20] });
    }
  }

  if (openPopup) {
    layer.openPopup();
  }
}

function setActiveRow(id) {
  if (activeRowId !== null) {
    const previousRow = elements.tableBody.querySelector(
      `tr[data-feature-id="${activeRowId}"]`
    );
    if (previousRow) {
      previousRow.classList.remove("active");
    }
  }

  const row = elements.tableBody.querySelector(`tr[data-feature-id="${id}"]`);
  if (!row) {
    activeRowId = null;
    return;
  }

  activeRowId = id;
  row.classList.add("active");
  row.scrollIntoView({ block: "nearest" });
}

function buildPopupContent(properties) {
  const rows = [
    { label: "ADM1_TH", value: properties.ADM1_TH },
    { label: "ADM2_TH", value: properties.ADM2_TH },
    { label: "ADM3_TH", value: properties.ADM3_TH },
    { label: "Area (m2)", value: formatNumber(properties.area_m2, 2) },
    { label: "Area (Rai)", value: formatNumber(properties.area_rai, 2) },
  ];

  const details = rows
    .map(({ label, value }) => `<div><strong>${label}:</strong> ${value ?? "-"}</div>`)
    .join("");

  return `<div class="popup-content"><h3>Palm Plot #${properties.id}</h3>${details}</div>`;
}

function formatNumber(value, fractionDigits = 0) {
  if (value === null || value === undefined || Number.isNaN(Number(value))) {
    return "-";
  }
  return new Intl.NumberFormat("en-US", {
    minimumFractionDigits: 0,
    maximumFractionDigits: fractionDigits,
  }).format(Number(value));
}

function setLoading(isLoading) {
  document.body.classList.toggle("is-loading", Boolean(isLoading));
  if (elements.loadingOverlay) {
    elements.loadingOverlay.setAttribute("aria-hidden", isLoading ? "false" : "true");
  }
}