import {
  ButtonBuilder,
  ButtonStyle,
  ActionRowBuilder,
} from "discord.js";
import { getCharacters, getCharacterByName } from "@systems/characters";
import { getClassEmoji } from "@systems/emojis";
import { format } from "@format";
import { Character } from "@types";
import fs from "fs";
import path from "path";

const CHARS_PATH = path.join(__dirname, "../../data/characters.json");

export interface CharSelectOptions {
  customIdPrefix: string;   // e.g. "switch_after_reclaim:flash"
  excludeCharName?: string; // exclude this char from the list
  appendToCustomId?: string; // appended after charName e.g. ":yes"
  pageSize?: number;         // default 4
  page?: number;             // default 0
}

/**
 * Builds paginated character selection button rows for a given user.
 * Includes own characters + shared characters.
 * Returns up to 2 rows: one for char buttons, one for pagination if needed.
 */
export function buildCharSelectButtons(
  userKey: string,
  options: CharSelectOptions
): ActionRowBuilder<ButtonBuilder>[] {
  const {
    customIdPrefix,
    excludeCharName,
    appendToCustomId = "",
    pageSize = 4,
    page = 0,
  } = options;

  // Gather own + shared chars
  const ownChars = getCharacters(userKey);

  const sharedChars: Character[] = [];
  try {
    const chars = JSON.parse(fs.readFileSync(CHARS_PATH, "utf8"));
    for (const [ownerKey, data] of Object.entries(chars) as [string, any][]) {
      if (ownerKey === userKey) continue;
      for (const c of data.characters ?? []) {
        if (c.sharedWith?.includes(userKey)) sharedChars.push(c);
      }
    }
  } catch {}

  const allChars = [...ownChars, ...sharedChars]
    .filter((c) => c.name !== excludeCharName);

  const pageChars = allChars.slice(page * pageSize, (page + 1) * pageSize);
  const hasNext   = allChars.length > (page + 1) * pageSize;
  const hasPrev   = page > 0;
  const rows: ActionRowBuilder<ButtonBuilder>[] = [];

  // Char buttons
  if (pageChars.length > 0) {
    const btns = pageChars.map((c) => {
      const emojiStr = getClassEmoji(c.class);
      const emoji    = format.emoji(emojiStr);
      const btn      = new ButtonBuilder()
        .setCustomId(`${customIdPrefix}:${c.name}${appendToCustomId}`)
        .setStyle(ButtonStyle.Secondary)
        .setLabel(`${c.level} ${c.name}`);
      if (emoji) btn.setEmoji(emoji as any);
      return btn;
    });
    rows.push(new ActionRowBuilder<ButtonBuilder>().addComponents(...btns));
  }

  // Pagination row
  const navBtns: ButtonBuilder[] = [];
  if (hasPrev) {
    navBtns.push(
      new ButtonBuilder()
        .setCustomId(`${customIdPrefix}_page:${page - 1}`)
        .setLabel("← Prev")
        .setStyle(ButtonStyle.Primary)
    );
  }
  if (hasNext) {
    navBtns.push(
      new ButtonBuilder()
        .setCustomId(`${customIdPrefix}_page:${page + 1}`)
        .setLabel("Next →")
        .setStyle(ButtonStyle.Primary)
    );
  }
  if (navBtns.length > 0) {
    rows.push(new ActionRowBuilder<ButtonBuilder>().addComponents(...navBtns));
  }

  return rows;
}