/**
 * @file Apotheosis service handling eligibility checks and state building.
 * @copyright nhcarrigan
 * @license Naomi's Public License
 * @author Naomi Carrigan
 */
import { initialGameState } from "../data/initialState.js";
import {
  defaultTranscendenceUpgrades,
} from "../data/transcendenceUpgrades.js";
import type { ApotheosisData, GameState } from "@elysium/types";

/**
 * Total number of echo upgrades — all must be purchased to unlock Apotheosis.
 */
const totalEchoUpgrades = defaultTranscendenceUpgrades.length;

/**
 * Returns true when the player is eligible to achieve Apotheosis:
 * all Transcendence echo upgrades must be purchased.
 * @param state - The current game state.
 * @returns Whether the player is eligible for Apotheosis.
 */
const isEligibleForApotheosis = (state: GameState): boolean => {
  const purchasedIds = state.transcendence?.purchasedUpgradeIds ?? [];
  return (
    purchasedIds.length >= totalEchoUpgrades
    && defaultTranscendenceUpgrades.every((u) => {
      return purchasedIds.includes(u.id);
    })
  );
};

/**
 * Builds the updated game state after Apotheosis — the ultimate nuclear reset.
 * Wipes absolutely everything including prestige and transcendence.
 * Only codex lore entries and the apotheosis count itself are preserved.
 * @param currentState - The current game state before apotheosis.
 * @param characterName - The character name to carry over.
 * @returns The updated game state and apotheosis data.
 */
const buildPostApotheosisState = (
  currentState: GameState,
  characterName: string,
): { updatedApotheosisData: ApotheosisData; updatedState: GameState } => {
  const apotheosisCount = (currentState.apotheosis?.count ?? 0) + 1;
  const updatedApotheosisData: ApotheosisData = { count: apotheosisCount };

  const freshState = initialGameState(currentState.player, characterName);
  const updatedState: GameState = {
    ...freshState,
    lastTickAt: Date.now(),
    // Codex lore persists through all resets — players keep their discovered entries
    ...currentState.codex
      ? { codex: currentState.codex }
      : {},
    // Apotheosis data is eternal — never wiped by any reset
    apotheosis: updatedApotheosisData,
    // Story chapter progress is permanent — survives all resets
    ...currentState.story
      ? { story: currentState.story }
      : {},
  };

  return { updatedApotheosisData, updatedState };
};

export { buildPostApotheosisState, isEligibleForApotheosis };