/** Keep one context address unambiguous inside the in-memory lookup table. */
function zoomKey(cmapSlug, contextKey) {
  return `${cmapSlug}\u0000${contextKey}`;
}

/**
 * Represent wiki and user settings for the CMap workspace.
 * The backend is authoritative; this object only caches the active session state.
 */
export class CmapSettingsRepository {
  constructor(api) {
    if (typeof api !== "function") throw new TypeError("A wiki API function is required");
    this.api = api;
    this.loaded = false;
    this.startCmapSlug = "";
    this.pageGuidesVisible = true;
    this.zoomLevels = new Map();
  }

  async load() {
    const result = await this.api("/api/cmap-settings");
    this.startCmapSlug = typeof result.startCmapSlug === "string" ? result.startCmapSlug : "";
    this.pageGuidesVisible = result.pageGuidesVisible !== false;
    this.zoomLevels.clear();
    for (const entry of (Array.isArray(result.zooms) ? result.zooms : [])) {
      const zoom = Number(entry.zoomPercent);
      if (entry.cmapSlug && entry.contextKey && zoom >= 25 && zoom <= 300) {
        this.zoomLevels.set(zoomKey(entry.cmapSlug, entry.contextKey), zoom);
      }
    }
    this.loaded = true;
    return this;
  }

  zoom(cmapSlug, contextKey) {
    return this.zoomLevels.get(zoomKey(cmapSlug, contextKey)) || 100;
  }

  async setStartCmap(slug) {
    const result = await this.api("/api/cmap-settings/start", {
      method: "PUT",
      body: JSON.stringify({ startCmapSlug: slug || "" })
    });
    this.startCmapSlug = result.startCmapSlug || "";
    return this.startCmapSlug;
  }

  async setPageGuidesVisible(visible) {
    const result = await this.api("/api/cmap-settings/page-guides", {
      method: "PUT",
      body: JSON.stringify({ pageGuidesVisible: Boolean(visible) })
    });
    this.pageGuidesVisible = result.pageGuidesVisible !== false;
    return this.pageGuidesVisible;
  }

  async setZoom(cmapSlug, contextKey, zoomPercent) {
    if (!cmapSlug) return zoomPercent;
    const result = await this.api("/api/cmap-settings/zoom", {
      method: "PUT",
      body: JSON.stringify({ cmapSlug, contextKey, zoomPercent })
    });
    const storedZoom = Number(result.zoomPercent);
    this.zoomLevels.set(zoomKey(cmapSlug, contextKey), storedZoom);
    return storedZoom;
  }
}