import { defineWidget } from '@dashward/widget-sdk';
import type { Theme, WidgetContext, WidgetDefinition, WidgetHost } from '@dashward/widget-sdk';

// =============================================================================
// Page-side runtime (design §11). P5 mounts the first real widget on the
// grid using the SDK's defineWidget abstraction. Layout persistence,
// edit mode, and dynamic widget loading from disk arrive in later phases.
// =============================================================================

// -----------------------------------------------------------------------------
// 1. Shell bridge — establishes window.__dashShell__ and follows the
//    system color-scheme via the DBus round-trip (introduced in P4).
// -----------------------------------------------------------------------------

interface PendingCall {
  resolve(value: unknown): void;
  reject(err: Error): void;
}

interface DashShellInternal {
  call<T = unknown>(method: string, args?: unknown): Promise<T>;
  _resolve(id: number, value: unknown): void;
  _reject(id: number, error: string): void;
  _onSignal(name: string, payload: unknown): void;
}

declare global {
  interface Window {
    __dashShell__?: DashShellInternal;
    webkit?: { messageHandlers: { shellCall: { postMessage(data: string): void } } };
  }
}

const pending = new Map<number, PendingCall>();
let nextId = 1;

const dashShell: DashShellInternal = {
  call<T>(method: string, args?: unknown): Promise<T> {
    return new Promise<T>((resolve, reject) => {
      const id = nextId++;
      pending.set(id, { resolve: resolve as (v: unknown) => void, reject });
      try {
        window.webkit!.messageHandlers.shellCall.postMessage(
          JSON.stringify({ id, method, args }),
        );
      } catch (e) {
        pending.delete(id);
        reject(e instanceof Error ? e : new Error(String(e)));
      }
    });
  },
  _resolve(id, value) {
    const p = pending.get(id);
    if (!p) return;
    pending.delete(id);
    p.resolve(value);
  },
  _reject(id, err) {
    const p = pending.get(id);
    if (!p) return;
    pending.delete(id);
    p.reject(new Error(err));
  },
  _onSignal(name, payload) {
    window.dispatchEvent(new CustomEvent(`dashward:${name}`, { detail: payload }));
  },
};

window.__dashShell__ = dashShell;

function applyTheme(theme: unknown): void {
  if (theme !== 'light' && theme !== 'dark') return;
  document.documentElement.dataset.theme = theme;
}

dashShell
  .call<Theme>('getTheme')
  .then(applyTheme)
  .catch(e => console.warn('[dashward] getTheme failed:', e));

window.addEventListener('dashward:ThemeChanged', evt => {
  applyTheme((evt as CustomEvent<unknown>).detail);
});

// -----------------------------------------------------------------------------
// 2. Widget mounting + context. P5 uses localStorage for config; shell-
//    mediated persistence per design §9 lands when the widgets actually
//    need cross-session config (clock's defaults are fine).
// -----------------------------------------------------------------------------

function createContext<T>(def: WidgetDefinition<T>, instanceId: string): WidgetContext<T> {
  const storageKey = `dashward:widget:${instanceId}:config`;

  let stored: Partial<T> = {};
  try {
    const raw = localStorage.getItem(storageKey);
    if (raw) stored = JSON.parse(raw) as Partial<T>;
  } catch (e) {
    console.warn(`[dashward] failed to read config for ${instanceId}:`, e);
  }
  let config: T = { ...def.defaultConfig, ...stored };

  const configHandlers = new Set<(v: T) => void>();
  const unmountHandlers = new Set<() => void>();

  return {
    config: {
      get: () => config,
      set: async (partial: Partial<T>) => {
        config = { ...config, ...partial };
        try {
          localStorage.setItem(storageKey, JSON.stringify(config));
        } catch (e) {
          console.warn(`[dashward] failed to persist config for ${instanceId}:`, e);
        }
        for (const cb of configHandlers) cb(config);
      },
      onChange: (cb: (v: T) => void) => {
        configHandlers.add(cb);
        return () => configHandlers.delete(cb);
      },
    },
    system: {
      getTheme: () => (document.documentElement.dataset.theme as Theme) ?? 'light',
      onThemeChange: (cb: (t: Theme) => void) => {
        const h = (e: Event) => cb((e as CustomEvent<Theme>).detail);
        window.addEventListener('dashward:ThemeChanged', h);
        return () => window.removeEventListener('dashward:ThemeChanged', h);
      },
    },
    lifecycle: {
      onMount: (cb: () => void) => {
        queueMicrotask(cb);
      },
      onUnmount: (cb: () => void) => {
        unmountHandlers.add(cb);
      },
      // P5 doesn't track per-widget visibility; widgets stay alive as long
      // as the dashboard page does. Returns a no-op unsubscriber.
      onVisibilityChange: () => () => {},
    },
    shell: {
      call: <R>(method: string, args?: unknown) => dashShell.call<R>(method, args),
    },
  };
}

function mountWidget<T>(
  def: WidgetDefinition<T>,
  parent: HTMLElement,
  instanceId: string,
  size: { w: number; h: number },
): void {
  const element = document.createElement('div');
  element.className = 'widget';
  element.dataset.widget = def.id;
  element.style.gridColumn = `span ${size.w}`;
  element.style.gridRow = `span ${size.h}`;
  parent.appendChild(element);

  const host: WidgetHost = { element, instanceId };
  const ctx = createContext(def, instanceId);

  try {
    def.mount(host, ctx);
  } catch (e) {
    console.error(`[dashward] widget "${def.id}" mount failed:`, e);
    element.classList.add('widget-error');
    element.textContent = `${def.id}: mount failed`;
  }
}

// -----------------------------------------------------------------------------
// 3. Built-in clock widget (inline in runtime for now; a proper widget
//    loader that reads widget.json from disk lands in P6+ along with the
//    other builtins).
// -----------------------------------------------------------------------------

interface ClockConfig {
  hour12: boolean;
  showSeconds: boolean;
}

const clockDef = defineWidget<ClockConfig>({
  id: 'clock',
  defaultConfig: { hour12: false, showSeconds: true },

  mount(host, ctx) {
    const root = host.element.attachShadow({ mode: 'open' });
    root.innerHTML = `
      <style>
        :host {
          display: grid;
          place-items: center;
          width: 100%;
          height: 100%;
        }
        .time {
          font: 200 clamp(2rem, 7vw, 4.5rem) ui-sans-serif, system-ui, sans-serif;
          font-variant-numeric: tabular-nums;
          letter-spacing: -0.02em;
        }
      </style>
      <div class="time"></div>
    `;
    const timeEl = root.querySelector('.time') as HTMLDivElement;

    const render = (): void => {
      const cfg = ctx.config.get();
      timeEl.textContent = new Date().toLocaleTimeString(undefined, {
        hour12: cfg.hour12,
        hour: '2-digit',
        minute: '2-digit',
        second: cfg.showSeconds ? '2-digit' : undefined,
      });
    };

    render();
    const timer = setInterval(render, 1000);
    ctx.lifecycle.onUnmount(() => clearInterval(timer));
    ctx.config.onChange(() => render());
  },
});

// -----------------------------------------------------------------------------
// 4. Boot — remove the diagnostic banner, mount widgets.
// -----------------------------------------------------------------------------

document.getElementById('boot')?.remove();

const grid = document.getElementById('grid');
if (grid) {
  mountWidget(clockDef, grid, 'clock-1', { w: 4, h: 2 });
}

console.info('[dashward-runtime] P5 mounted clock widget');