// Per-user settings with localStorage fallback
// Feature Registration Pattern implementation

import type { ReaderContext } from "./core/reader-context";
import { apiGet, apiPut } from "../api";
import { getToken } from "../storage";

const LOCALSTORAGE_KEY = "reader_settings_local";

export function init(context: ReaderContext): void {
  let currentSettings: ReaderSettings | null = null;

  context.events.on("reader:init", async () => {
    currentSettings = await loadSettings();
    context.events.emit("settings:loaded", currentSettings);
  });

  context.events.on(
    "settings:save",
    async (detail: { settings: Partial<ReaderSettings> }) => {
      await saveSettings(detail.settings);
      currentSettings = await loadSettings();
      context.events.emit("settings:changed", currentSettings);
    },
  );

  context.events.on(
    "settings:get",
    (detail: { key?: keyof ReaderSettings }) => {
      if (currentSettings) {
        const value = detail.key
          ? currentSettings[detail.key]
          : currentSettings;
        context.events.emit("settings:current", { value });
      }
    },
  );

  context.events.on(
    "settings:set",
    async (detail: { key: keyof ReaderSettings; value: any }) => {
      await saveSettings({ [detail.key]: detail.value });
      currentSettings = await loadSettings();
      context.events.emit("settings:changed", currentSettings);
    },
  );

  context.events.on("settings:sync", async () => {
    await syncSettings();
    currentSettings = await loadSettings();
    context.events.emit("settings:synced", currentSettings);
  });
}

async function loadSettings(): Promise<ReaderSettings> {
  const token = getToken();
  if (!token) {
    const local = localStorage.getItem(LOCALSTORAGE_KEY);
    return local ? JSON.parse(local) : getDefaultSettings();
  }

  try {
    const response = await apiGet("/readers/settings");
    const settings = await response.json();
    localStorage.setItem(LOCALSTORAGE_KEY, JSON.stringify(settings));
    return settings;
  } catch (error) {
    const local = localStorage.getItem(LOCALSTORAGE_KEY);
    return local ? JSON.parse(local) : getDefaultSettings();
  }
}

async function saveSettings(settings: Partial<ReaderSettings>): Promise<void> {
  const token = getToken();
  const current = await loadSettings();
  const updated = { ...current, ...settings };

  if (!token) {
    localStorage.setItem(LOCALSTORAGE_KEY, JSON.stringify(updated));
    return;
  }

  try {
    await apiPut("/readers/settings", settings);
    localStorage.setItem(LOCALSTORAGE_KEY, JSON.stringify(updated));
  } catch (error) {
    localStorage.setItem(LOCALSTORAGE_KEY, JSON.stringify(updated));
  }
}

async function syncSettings(): Promise<void> {
  const local = localStorage.getItem(LOCALSTORAGE_KEY);
  if (!local) return;

  const settings = JSON.parse(local);
  const token = getToken();

  if (token) {
    try {
      await apiPut("/readers/settings", settings);
    } catch (error) {
      console.error("Failed to sync settings:", error);
    }
  }
}

export function getDefaultSettings(): ReaderSettings {
  return {
    chrome_behavior: "auto-hide",
    progress_mode: "pages",
    chrome_theme: "tokyo-night",
    reading_theme: "dark",
    reading_font: "literata",
    tap_zone_size: 30,
    auto_scroll: false,
    panel_zoom_enabled: true,
    font_size: 16,
    line_height: 1.6,
    margin_width: 20,
    double_page_spread: false,
    reading_direction: "ltr",
    hardware_acceleration: true,
    panel_layout: {
      toc: {
        side: "left",
        visible: true,
        collapsed: false,
        width_px: 320,
        order: 1,
        locked: false,
        last_valid_side: "left",
      },
      settings: {
        side: "left",
        visible: false,
        collapsed: true,
        width_px: 380,
        order: 2,
        locked: false,
        last_valid_side: "left",
      },
      navigator: {
        side: "right",
        visible: false,
        collapsed: true,
        width_px: 280,
        order: 3,
        locked: false,
        last_valid_side: "right",
      },
      bookmarks: {
        side: "right",
        visible: false,
        collapsed: true,
        width_px: 280,
        order: 4,
        locked: false,
        last_valid_side: "right",
      },
      mobile_nav_visible: true,
    },
  } as ReaderSettings;
}