import { vi } from 'vitest';
import type { ExecutionPlan } from '../../src/generated/common.js';
import type { RemoteConfig } from '../../src/generated/remote-config.js';
import type { Store } from '../../src/generated/stores.js';
import type { StorageItem } from '../../src/generated/storage.js';
import type {
  ClaimQuestResponse,
  ListQuestsResponse,
} from '../../src/generated/quests.js';

/**
 * In-process fake of the LiveOps API gateway.
 *
 * Stubs the global `fetch` and routes requests the same way the real gateway
 * does — so tests exercise the *real* SDK transport, auth-header injection,
 * scenario engine and DAG traversal, just against deterministic in-memory state
 * instead of a live backend.
 *
 * Seed state up front (scenarios per event, remote configs, stores), then drive
 * the SDK through a journey and assert on `recorded` requests / server state.
 */

export interface RecordedRequest {
  method: string;
  path: string;
  query: URLSearchParams;
  body: unknown;
  authToken: string | null;
}

export interface FakeGatewayState {
  /** Plans returned by POST /scenarios/trigger, keyed by event name. */
  scenarios: Map<string, ExecutionPlan[]>;
  /** Plans returned by POST /scenarios/callback, keyed by `nodeId:handle`. */
  callbacks: Map<string, ExecutionPlan>;
  /** HTTP status to fail a callback with, keyed by `nodeId:handle`. */
  callbackErrors: Map<string, number>;
  /** Optional response for POST /scenarios/counter. */
  counterPlan?: ExecutionPlan;
  remoteConfigs: Record<string, RemoteConfig>;
  stores: Store[];
  quests: ListQuestsResponse;
  questClaims: Map<string, ClaimQuestResponse>;
  /** Player KV storage, keyed by item id. */
  storage: Map<string, StorageItem>;
}

export interface FakeGateway {
  state: FakeGatewayState;
  recorded: RecordedRequest[];
  /** Purchases received, in order. */
  purchases: Array<{ storeSlug: string; offerId: string; idempotencyKey: string; authToken: string | null }>;
  /** Quest claim requests received, in order. */
  questClaims: Array<{ questId: string; authToken: string | null }>;
  install(): void;
  /** Convenience: register the plans returned for a trigger event. */
  onEvent(event: string, ...plans: ExecutionPlan[]): void;
  /** Convenience: register the plan returned when a boundary handle calls back. */
  onCallback(nodeId: string, handle: string, plan: ExecutionPlan): void;
  /** Convenience: make a boundary callback fail with an HTTP status (default 500). */
  onCallbackError(nodeId: string, handle: string, status?: number): void;
}

function json(body: unknown, status = 200): Response {
  return new Response(JSON.stringify(body), {
    status,
    headers: { 'Content-Type': 'application/json' },
  });
}

const noContent = (): Response => new Response(null, { status: 204 });

export function createFakeGateway(seed?: Partial<FakeGatewayState>): FakeGateway {
  const state: FakeGatewayState = {
    scenarios: seed?.scenarios ?? new Map(),
    callbacks: seed?.callbacks ?? new Map(),
    callbackErrors: seed?.callbackErrors ?? new Map(),
    counterPlan: seed?.counterPlan,
    remoteConfigs: seed?.remoteConfigs ?? {},
    stores: seed?.stores ?? [],
    quests: seed?.quests ?? { quests: [] },
    questClaims: seed?.questClaims ?? new Map(),
    storage: seed?.storage ?? new Map(),
  };

  const recorded: RecordedRequest[] = [];
  const purchases: FakeGateway['purchases'] = [];
  const questClaims: FakeGateway['questClaims'] = [];

  async function handle(req: RecordedRequest): Promise<Response> {
    const { method, path, query, body } = req;

    // --- Auth ---
    if (method === 'POST' && path === '/sdk/v1/authorization/device') {
      const b = body as { deviceId?: string };
      return json({
        accessToken: `access-${b.deviceId ?? 'dev'}`,
        refreshToken: `refresh-${b.deviceId ?? 'dev'}`,
      });
    }

    // --- Player ---
    if (method === 'GET' && path === '/sdk/v1/player/information') {
      return json({ player: null, wallets: [] });
    }

    // --- Sync (baseline revision poll after login) ---
    if (method === 'GET' && path === '/sdk/v1/sync') {
      return json({});
    }

    // --- Catalog ---
    if (method === 'GET' && path === '/sdk/v1/catalog') {
      return json({ items: [] });
    }

    // --- Scenarios ---
    if (method === 'POST' && path === '/sdk/v1/scenarios/trigger') {
      const event = (body as { event?: string }).event ?? '';
      return json({ plans: state.scenarios.get(event) ?? [] });
    }
    if (method === 'POST' && path === '/sdk/v1/scenarios/callback') {
      const b = body as { nodeId?: string; handle?: string };
      const key = `${b.nodeId}:${b.handle}`;
      const errStatus = state.callbackErrors.get(key);
      if (errStatus) return json({ error: 'callback failed' }, errStatus);
      const plan = state.callbacks.get(key);
      return json(plan ? { plan } : {});
    }
    if (method === 'POST' && path === '/sdk/v1/scenarios/counter') {
      return json(state.counterPlan ? { plan: state.counterPlan, completed: false } : { completed: false });
    }

    // --- Remote config ---
    if (method === 'GET' && path === '/sdk/v1/remote-configs') {
      return json({ configs: state.remoteConfigs });
    }
    if (method === 'GET' && path.startsWith('/sdk/v1/remote-configs/')) {
      const key = decodeURIComponent(path.slice('/sdk/v1/remote-configs/'.length));
      const cfg = state.remoteConfigs[key];
      return cfg ? json(cfg) : json({ error: 'not found' }, 404);
    }

    // --- Stores ---
    if (method === 'GET' && path === '/sdk/v1/stores') {
      return json({ stores: state.stores, total: state.stores.length });
    }
    const purchaseMatch = path.match(/^\/sdk\/v1\/stores\/([^/]+)\/offers\/([^/]+)\/purchase$/);
    if (method === 'POST' && purchaseMatch) {
      const b = body as { idempotencyKey?: string };
      purchases.push({
        storeSlug: decodeURIComponent(purchaseMatch[1]),
        offerId: decodeURIComponent(purchaseMatch[2]),
        idempotencyKey: b.idempotencyKey ?? '',
        authToken: req.authToken,
      });
      return json({ success: true, purchaseId: `purchase-${purchases.length}` });
    }
    const storeMatch = path.match(/^\/sdk\/v1\/stores\/([^/]+)$/);
    if (method === 'GET' && storeMatch) {
      const slug = decodeURIComponent(storeMatch[1]);
      const store = state.stores.find((s) => s.slug === slug);
      return store ? json(store) : json({ error: 'not found' }, 404);
    }

    // --- Quests ---
    if (method === 'POST' && path === '/sdk/v1/quests/list') {
      return json(state.quests);
    }
    if (method === 'POST' && path === '/sdk/v1/quests/claim') {
      const b = body as { questId?: string };
      const questId = b.questId ?? '';
      questClaims.push({ questId, authToken: req.authToken });
      return json(state.questClaims.get(questId) ?? { success: false, error: 'not found' });
    }

    // --- Storage ---
    if (path === '/sdk/v1/storage') {
      if (method === 'GET') {
        const typeFilter = query.get('types');
        const items = [...state.storage.values()].filter(
          (it) => !typeFilter || it.type === typeFilter,
        );
        return json({ items, nextCursor: '' });
      }
      if (method === 'PUT') {
        const items = (body as { items?: StorageItem[] }).items ?? [];
        for (const item of items) {
          if (item.id) state.storage.set(item.id, item);
        }
        return noContent();
      }
      if (method === 'DELETE') {
        const type = query.get('type');
        for (const [id, item] of state.storage) {
          if (!type || item.type === type) state.storage.delete(id);
        }
        return noContent();
      }
    }

    return json({ error: `unhandled route: ${method} ${path}` }, 500);
  }

  function install(): void {
    vi.stubGlobal(
      'fetch',
      vi.fn(async (input: string | URL, init?: RequestInit): Promise<Response> => {
        const url = new URL(typeof input === 'string' ? input : input.toString());
        const headers = new Headers(init?.headers);
        const auth = headers.get('Authorization');
        const req: RecordedRequest = {
          method: (init?.method ?? 'GET').toUpperCase(),
          path: url.pathname,
          query: url.searchParams,
          body: init?.body ? JSON.parse(init.body as string) : undefined,
          authToken: auth ? auth.replace(/^Bearer\s+/, '') : null,
        };
        recorded.push(req);
        return handle(req);
      }),
    );
  }

  return {
    state,
    recorded,
    purchases,
    questClaims,
    install,
    onEvent(event, ...plans) {
      state.scenarios.set(event, plans);
    },
    onCallback(nodeId, handle, plan) {
      state.callbacks.set(`${nodeId}:${handle}`, plan);
    },
    onCallbackError(nodeId, handle, status = 500) {
      state.callbackErrors.set(`${nodeId}:${handle}`, status);
    },
  };
}