import { EmbedBuilder } from "discord.js";
import { PollState, VoteEntry, Nation } from "@types";
import { Config } from "@systems/config";
import { PollLayout, PollRowContext, PollEmbedOptions } from "@ui/types";
import path from "path";
import fs from "fs";
import { Runtime } from "@systems/runtime";

// ─── Runtime ──────────────────────────────────────────────────────────────────
Runtime.phase("restore", () => restoreLayout(), { name: "PollUI.restoreLayout" });

// ─── Layout registry ──────────────────────────────────────────────────────────

const _layouts = new Map<string, PollLayout>();
let _activeLayout: PollLayout;

export function registerLayout(layout: PollLayout): void {
  _layouts.set(layout.name, layout);
  if (!_activeLayout) _activeLayout = layout; // first registered = default
}

function isPollLayout(obj: any): obj is PollLayout {
  return obj?.name &&
    obj?.description &&
    typeof obj?.buildEmbed   === "function" &&
    typeof obj?.formatRow    === "function" &&
    typeof obj?.buildContext === "function";
}

export function discoverLayouts(): void {
  const layoutsDir = path.join(__dirname, "layouts");
  if (!fs.existsSync(layoutsDir)) return;

  const files = fs.readdirSync(layoutsDir)
    .filter((f) => f.endsWith(".ts") || f.endsWith(".js"))
    .sort(); // consistent order — default.ts loads before side-by-side.ts

  for (const file of files) {
    try {
      const mod = require(path.join(layoutsDir, file));
      for (const exported of Object.values(mod)) {
        if (isPollLayout(exported)) {
          registerLayout(exported);
          console.log(`[PollUI] Registered layout: ${(exported as PollLayout).name}`);
        }
      }
    } catch (err) {
      console.error(`[PollUI] Failed to load layout ${file}:`, err);
    }
  }
}

function restoreLayout() {
  const savedLayout = Config.get({ section: "poll", key: "layout" });

  if (savedLayout && _layouts.has(savedLayout)) {
    _activeLayout = _layouts.get(savedLayout)!;
    console.log(`[PollUI] Restored layout: ${savedLayout}`);
  }
}

// Auto-discover at module load time
Config.load();
discoverLayouts();
restoreLayout();

// ─── Dispatcher ───────────────────────────────────────────────────────────────

function activeLayout(): PollLayout {
  return _activeLayout;
}

export const PollUI = {
  buildEmbed(state: PollState, options?: PollEmbedOptions): EmbedBuilder {
    return activeLayout().buildEmbed(state, options);
  },

  formatRow(entry: VoteEntry, context: PollRowContext): string {
    return activeLayout().formatRow(entry, context);
  },

  buildContext(
    entries: VoteEntry[],
    nation: Nation,
    options?: { showNationEmoji?: boolean }
  ): PollRowContext {
    return activeLayout().buildContext(entries, nation, options);
  },

  setLayout(name: string): boolean {
    const layout = _layouts.get(name);
    if (!layout) return false;
    _activeLayout = layout;
    return true;
  },

  layouts(): { name: string; description: string }[] {
    return [..._layouts.values()].map((l) => ({
      name:        l.name,
      description: l.description,
    }));
  },

  register: registerLayout,
};