import { NOTE_PIN_ICON } from "/js/icons.js";
import { notifyGpxStoreChanged } from "/js/panels.js";

const NEW_LAYER_VALUE = "__new__";
const PREVIEW_SOURCE_ID = "notes-preview";
const PREVIEW_FILL_LAYER_ID = "notes-preview-fill";
const PREVIEW_LINE_LAYER_ID = "notes-preview-line";
const PREVIEW_POINT_LAYER_ID = "notes-preview-points";
const PREVIEW_COLOR = "#c0392b";

// A quick "pin it with a note" tool — click the map (Point mode) or click
// out a few corners and Finish (Area mode), write a short note, pick which
// .geojson "layer" file it joins (or start a new one). Saved server-side
// (POST /api/gpx/notes) into the same GpxStore everything else in the
// Tracks panel already reads from, so a note shows up there with no
// separate rendering path of its own: same tree, same checkbox visibility,
// same popup — public/js/gpx.js's _addLayers renders a Polygon feature the
// same way it already renders points/lines, no separate code path here.
export class NotesControl {
  constructor() {
    this._active = false;
    this._mode = "point"; // "point" | "area"
    this._areaPoints = []; // vertices while drawing an area, before Finish
    this._pendingGeometry = null; // the finished Point/Polygon geometry, once placed
  }

  onAdd(map) {
    this._map = map;

    this._container = document.createElement("div");
    this._container.className = "maplibregl-ctrl maplibregl-ctrl-group notes-ctrl";
    this._container.innerHTML = `
      <button type="button" class="notes-ctrl__button" title="Add note" aria-label="Add note">${NOTE_PIN_ICON}</button>
      <div class="notes-panel" hidden>
        <div class="notes-panel__modes">
          <button type="button" class="notes-panel__mode active" data-mode="point">Point</button>
          <button type="button" class="notes-panel__mode" data-mode="area">Area</button>
        </div>
        <p class="notes-panel__hint"></p>
        <button type="button" class="notes-panel__finish" hidden>Finish shape</button>
        <div class="notes-panel__form" hidden>
          <textarea class="notes-panel__text" rows="2" placeholder="Note…"></textarea>
          <select class="notes-panel__target"></select>
          <input type="text" class="notes-panel__new-name" placeholder="Layer name" hidden>
          <div class="notes-panel__actions">
            <button type="button" class="notes-panel__save">Save</button>
            <button type="button" class="notes-panel__cancel">Cancel</button>
          </div>
        </div>
      </div>
    `;
    this._button = this._container.querySelector(".notes-ctrl__button");
    this._panel = this._container.querySelector(".notes-panel");
    this._hint = this._container.querySelector(".notes-panel__hint");
    this._finishButton = this._container.querySelector(".notes-panel__finish");
    this._form = this._container.querySelector(".notes-panel__form");
    this._text = this._container.querySelector(".notes-panel__text");
    this._target = this._container.querySelector(".notes-panel__target");
    this._newName = this._container.querySelector(".notes-panel__new-name");

    this._button.addEventListener("click", () => this._setActive(!this._active));
    this._panel.querySelectorAll(".notes-panel__mode").forEach((button) => {
      button.addEventListener("click", () => this._setMode(button.dataset.mode));
    });
    this._finishButton.addEventListener("click", () => this._finishArea());
    this._target.addEventListener("change", () => {
      this._newName.hidden = this._target.value !== NEW_LAYER_VALUE;
      if (!this._newName.hidden) this._newName.focus();
    });
    this._container.querySelector(".notes-panel__save").addEventListener("click", () => this._save());
    this._container.querySelector(".notes-panel__cancel").addEventListener("click", () => this._resetForm());

    this._onClick = (event) => {
      if (!this._active || !this._form.hidden) return;
      if (this._mode === "point") {
        this._pendingGeometry = { type: "Point", coordinates: [event.lngLat.lng, event.lngLat.lat] };
        this._openForm();
      } else {
        this._areaPoints.push([event.lngLat.lng, event.lngLat.lat]);
        this._renderPreview();
        this._updateAreaUi();
      }
    };
    map.on("click", this._onClick);

    map.on("style.load", () => {
      if (this._areaPoints.length > 0) this._addPreviewLayers();
    });

    this._updateHint();
    return this._container;
  }

  onRemove() {
    this._map.off("click", this._onClick);
    this._container.remove();
  }

  getDefaultPosition() {
    return "top-left";
  }

  _setActive(active) {
    this._active = active;
    this._button.classList.toggle("active", active);
    this._panel.hidden = !active;
    this._map.getCanvas().style.cursor = active ? "crosshair" : "";
    if (!active) {
      this._clearArea();
      this._resetForm();
    }
  }

  _setMode(mode) {
    this._mode = mode;
    this._panel.querySelectorAll(".notes-panel__mode").forEach((button) => {
      button.classList.toggle("active", button.dataset.mode === mode);
    });
    this._clearArea();
    this._updateHint();
  }

  _clearArea() {
    this._areaPoints = [];
    this._renderPreview();
    this._updateAreaUi();
  }

  _updateAreaUi() {
    this._finishButton.hidden = this._mode !== "area" || this._areaPoints.length < 3;
    this._updateHint();
  }

  _updateHint() {
    if (this._mode === "point") {
      this._hint.textContent = "Click the map to place a note.";
    } else if (this._areaPoints.length === 0) {
      this._hint.textContent = "Click to start drawing an area.";
    } else {
      this._hint.textContent = `${this._areaPoints.length} corner${this._areaPoints.length === 1 ? "" : "s"} — click to add more${
        this._areaPoints.length >= 3 ? ", or Finish" : ""
      }.`;
    }
  }

  _finishArea() {
    if (this._areaPoints.length < 3) return;
    this._pendingGeometry = { type: "Polygon", coordinates: [[...this._areaPoints, this._areaPoints[0]]] };
    this._openForm();
  }

  _addPreviewLayers() {
    if (this._map.getSource(PREVIEW_SOURCE_ID)) return;
    this._map.addSource(PREVIEW_SOURCE_ID, { type: "geojson", data: emptyCollection() });
    this._map.addLayer({
      id: PREVIEW_FILL_LAYER_ID,
      type: "fill",
      source: PREVIEW_SOURCE_ID,
      filter: ["==", ["geometry-type"], "Polygon"],
      paint: { "fill-color": PREVIEW_COLOR, "fill-opacity": 0.15 },
    });
    this._map.addLayer({
      id: PREVIEW_LINE_LAYER_ID,
      type: "line",
      source: PREVIEW_SOURCE_ID,
      filter: ["!=", ["geometry-type"], "Point"],
      paint: { "line-color": PREVIEW_COLOR, "line-width": 2, "line-dasharray": [2, 1] },
    });
    this._map.addLayer({
      id: PREVIEW_POINT_LAYER_ID,
      type: "circle",
      source: PREVIEW_SOURCE_ID,
      filter: ["==", ["geometry-type"], "Point"],
      paint: { "circle-radius": 4, "circle-color": "#fff", "circle-stroke-color": PREVIEW_COLOR, "circle-stroke-width": 2 },
    });
  }

  _removePreviewLayers() {
    [PREVIEW_FILL_LAYER_ID, PREVIEW_LINE_LAYER_ID, PREVIEW_POINT_LAYER_ID].forEach((id) => {
      if (this._map.getLayer(id)) this._map.removeLayer(id);
    });
    if (this._map.getSource(PREVIEW_SOURCE_ID)) this._map.removeSource(PREVIEW_SOURCE_ID);
  }

  _renderPreview() {
    if (this._areaPoints.length === 0) {
      this._removePreviewLayers();
      return;
    }
    this._addPreviewLayers();
    const pointFeatures = this._areaPoints.map((coord) => ({ type: "Feature", properties: {}, geometry: { type: "Point", coordinates: coord } }));
    // A closed ring needs 3+ vertices to be valid; with fewer, preview it as
    // an open line so a half-drawn shape still shows something.
    const shape =
      this._areaPoints.length >= 3
        ? { type: "Feature", properties: {}, geometry: { type: "Polygon", coordinates: [[...this._areaPoints, this._areaPoints[0]]] } }
        : this._areaPoints.length === 2
          ? { type: "Feature", properties: {}, geometry: { type: "LineString", coordinates: this._areaPoints } }
          : null;
    this._map.getSource(PREVIEW_SOURCE_ID)?.setData({ type: "FeatureCollection", features: [...(shape ? [shape] : []), ...pointFeatures] });
  }

  async _openForm() {
    this._hint.hidden = true;
    this._finishButton.hidden = true;
    this._panel.querySelector(".notes-panel__modes").hidden = true;
    this._form.hidden = false;
    this._text.value = "";
    this._text.focus();
    await this._populateTargets();
  }

  _resetForm() {
    this._pendingGeometry = null;
    this._hint.hidden = false;
    this._panel.querySelector(".notes-panel__modes").hidden = false;
    this._form.hidden = true;
    this._newName.hidden = true;
    this._newName.value = "";
    this._updateAreaUi();
  }

  async _populateTargets() {
    const previousValue = this._target.value;
    let files = [];
    try {
      const tree = await (await fetch("/api/gpx/tree")).json();
      files = geojsonFiles(tree);
    } catch (err) {
      // Tree fetch failed — target select just falls back to "new layer"
      // only, still usable.
    }

    this._target.innerHTML =
      files.map((file) => `<option value="${escapeAttr(file.path)}">${escapeText(file.path)}</option>`).join("") +
      `<option value="${NEW_LAYER_VALUE}">+ New layer…</option>`;
    this._target.value = files.some((file) => file.path === previousValue) ? previousValue : NEW_LAYER_VALUE;
    this._newName.hidden = this._target.value !== NEW_LAYER_VALUE;
  }

  async _save() {
    const text = this._text.value.trim();
    if (!text || !this._pendingGeometry) return;

    const isNewLayer = this._target.value === NEW_LAYER_VALUE;
    const name = isNewLayer ? this._newName.value.trim() : "";
    if (isNewLayer && !name) {
      this._newName.focus();
      return;
    }

    const feature = {
      type: "Feature",
      properties: { name: text, category: "Note", time: new Date().toISOString() },
      geometry: this._pendingGeometry,
    };

    const body = new URLSearchParams({ feature: JSON.stringify(feature) });
    if (isNewLayer) body.set("name", name);
    else body.set("path", this._target.value);

    const saveButton = this._container.querySelector(".notes-panel__save");
    saveButton.disabled = true;
    try {
      const response = await fetch("/api/gpx/notes", { method: "POST", body });
      if (!response.ok) throw new Error(`save failed: ${response.status}`);
      notifyGpxStoreChanged();
      this._clearArea();
      this._resetForm();
    } catch (err) {
      window.alert("Could not save the note — check your connection and try again.");
    } finally {
      saveButton.disabled = false;
    }
  }
}

function emptyCollection() {
  return { type: "FeatureCollection", features: [] };
}

function geojsonFiles(node, results = []) {
  if (node.type === "file" && node.path.toLowerCase().endsWith(".geojson")) {
    results.push({ path: node.path });
  }
  (node.children || []).forEach((child) => geojsonFiles(child, results));
  return results;
}

function escapeAttr(value) {
  return value.replace(/&/g, "&amp;").replace(/"/g, "&quot;");
}

function escapeText(value) {
  return value.replace(/&/g, "&amp;").replace(/</g, "&lt;");
}