import type { GameState } from '@ai-tycoon/shared';
import {
  INITIAL_SETTINGS, SAVE_VERSION,
  INITIAL_ECONOMY, INITIAL_INFRASTRUCTURE, INITIAL_COMPUTE,
  INITIAL_RESEARCH, INITIAL_MODELS, INITIAL_MARKET,
  INITIAL_COMPETITORS, INITIAL_TALENT, INITIAL_DATA,
  INITIAL_REPUTATION, INITIAL_ACHIEVEMENTS,
} from '@ai-tycoon/shared';

export type DeepPartial<T> = T extends object
  ? { [K in keyof T]?: DeepPartial<T[K]> }
  : T;

function deepMerge<T>(target: T, source: DeepPartial<T>): T {
  if (source === undefined || source === null) return target;
  if (typeof target !== 'object' || target === null) return source as T;
  if (Array.isArray(source)) return source as unknown as T;

  const result = { ...target };
  for (const key of Object.keys(source) as (keyof T)[]) {
    const srcVal = source[key];
    if (srcVal === undefined) continue;
    const tgtVal = result[key];
    if (
      typeof tgtVal === 'object' && tgtVal !== null && !Array.isArray(tgtVal) &&
      typeof srcVal === 'object' && srcVal !== null && !Array.isArray(srcVal)
    ) {
      result[key] = deepMerge(tgtVal, srcVal as DeepPartial<typeof tgtVal>);
    } else {
      result[key] = srcVal as T[keyof T];
    }
  }
  return result;
}

function baseState(): GameState {
  return {
    meta: {
      saveVersion: SAVE_VERSION,
      companyName: 'TestCorp',
      currentEra: 'startup',
      tickCount: 0,
      lastTickTimestamp: Date.now(),
      gameSpeed: 1,
      isPaused: false,
      createdAt: Date.now(),
      totalPlayTime: 0,
      settings: { ...INITIAL_SETTINGS },
    },
    economy: structuredClone(INITIAL_ECONOMY),
    infrastructure: structuredClone(INITIAL_INFRASTRUCTURE),
    compute: structuredClone(INITIAL_COMPUTE),
    research: structuredClone(INITIAL_RESEARCH),
    models: structuredClone(INITIAL_MODELS),
    market: structuredClone(INITIAL_MARKET),
    competitors: structuredClone(INITIAL_COMPETITORS),
    talent: structuredClone(INITIAL_TALENT),
    data: structuredClone(INITIAL_DATA),
    reputation: structuredClone(INITIAL_REPUTATION),
    achievements: structuredClone(INITIAL_ACHIEVEMENTS),
  };
}

export function createTestState(overrides?: DeepPartial<GameState>): GameState {
  const state = baseState();
  if (!overrides) return state;
  return deepMerge(state, overrides);
}