// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

import {env, InferenceSession} from 'onnxruntime-common';

import {OrtWasmMessage, SerializableInternalBuffer, SerializableSessionMetadata, SerializableTensorMetadata, TensorMetadata} from './proxy-messages';
import * as core from './wasm-core-impl';
import {initializeWebAssembly} from './wasm-factory';

const isProxy = (): boolean => !!env.wasm.proxy && typeof document !== 'undefined';
let proxyWorker: Worker|undefined;
let initializing = false;
let initialized = false;
let aborted = false;

type PromiseCallbacks<T = void> = [resolve: (result: T) => void, reject: (reason: unknown) => void];
let initWasmCallbacks: PromiseCallbacks;
const queuedCallbacks: Map<OrtWasmMessage['type'], Array<PromiseCallbacks<unknown>>> = new Map();

const enqueueCallbacks = (type: OrtWasmMessage['type'], callbacks: PromiseCallbacks<unknown>): void => {
  const queue = queuedCallbacks.get(type);
  if (queue) {
    queue.push(callbacks);
  } else {
    queuedCallbacks.set(type, [callbacks]);
  }
};

const ensureWorker = (): void => {
  if (initializing || !initialized || aborted || !proxyWorker) {
    throw new Error('worker not ready');
  }
};

const onProxyWorkerMessage = (ev: MessageEvent<OrtWasmMessage>): void => {
  switch (ev.data.type) {
    case 'init-wasm':
      initializing = false;
      if (ev.data.err) {
        aborted = true;
        initWasmCallbacks[1](ev.data.err);
      } else {
        initialized = true;
        initWasmCallbacks[0]();
      }
      break;
    case 'init-ep':
    case 'copy-from':
    case 'create':
    case 'release':
    case 'run':
    case 'end-profiling': {
      const callbacks = queuedCallbacks.get(ev.data.type)!;
      if (ev.data.err) {
        callbacks.shift()![1](ev.data.err);
      } else {
        callbacks.shift()![0](ev.data.out!);
      }
      break;
    }
    default:
  }
};

const scriptSrc = typeof document !== 'undefined' ? (document?.currentScript as HTMLScriptElement)?.src : undefined;

export const initializeWebAssemblyAndOrtRuntime = async(): Promise<void> => {
  if (initialized) {
    return;
  }
  if (initializing) {
    throw new Error('multiple calls to \'initWasm()\' detected.');
  }
  if (aborted) {
    throw new Error('previous call to \'initWasm()\' failed.');
  }

  initializing = true;

  if (!BUILD_DEFS.DISABLE_WASM_PROXY && isProxy()) {
    // overwrite wasm filepaths
    if (env.wasm.wasmPaths === undefined) {
      if (scriptSrc && scriptSrc.indexOf('blob:') !== 0) {
        env.wasm.wasmPaths = scriptSrc.substr(0, +(scriptSrc).lastIndexOf('/') + 1);
      }
    }

    return new Promise<void>((resolve, reject) => {
      proxyWorker?.terminate();

      const workerUrl = URL.createObjectURL(new Blob(
          [
            // This require() function is handled by esbuild plugin to load file content as string.
            // eslint-disable-next-line @typescript-eslint/no-require-imports
            require('./proxy-worker/main')
          ],
          {type: 'text/javascript'}));
      proxyWorker = new Worker(workerUrl, {name: 'ort-wasm-proxy-worker'});
      proxyWorker.onerror = (ev: ErrorEvent) => reject(ev);
      proxyWorker.onmessage = onProxyWorkerMessage;
      URL.revokeObjectURL(workerUrl);
      initWasmCallbacks = [resolve, reject];
      const message: OrtWasmMessage = {type: 'init-wasm', in : env};
      proxyWorker.postMessage(message);
    });

  } else {
    try {
      await initializeWebAssembly(env.wasm);
      await core.initRuntime(env);
      initialized = true;
    } catch (e) {
      aborted = true;
      throw e;
    } finally {
      initializing = false;
    }
  }
};

export const initializeOrtEp = async(epName: string): Promise<void> => {
  if (!BUILD_DEFS.DISABLE_WASM_PROXY && isProxy()) {
    ensureWorker();
    return new Promise<void>((resolve, reject) => {
      enqueueCallbacks('init-ep', [resolve, reject]);
      const message: OrtWasmMessage = {type: 'init-ep', in : {epName, env}};
      proxyWorker!.postMessage(message);
    });
  } else {
    await core.initEp(env, epName);
  }
};

export const copyFromExternalBuffer = async(buffer: Uint8Array): Promise<SerializableInternalBuffer> => {
  if (!BUILD_DEFS.DISABLE_WASM_PROXY && isProxy()) {
    ensureWorker();
    return new Promise<SerializableInternalBuffer>((resolve, reject) => {
      enqueueCallbacks('copy-from', [resolve, reject]);
      const message: OrtWasmMessage = {type: 'copy-from', in : {buffer}};
      proxyWorker!.postMessage(message, [buffer.buffer]);
    });
  } else {
    return core.copyFromExternalBuffer(buffer);
  }
};

export const createSession =
    async(model: SerializableInternalBuffer|Uint8Array, options?: InferenceSession.SessionOptions):
        Promise<SerializableSessionMetadata> => {
          if (!BUILD_DEFS.DISABLE_WASM_PROXY && isProxy()) {
            // check unsupported options
            if (options?.preferredOutputLocation) {
              throw new Error('session option "preferredOutputLocation" is not supported for proxy.');
            }
            ensureWorker();
            return new Promise<SerializableSessionMetadata>((resolve, reject) => {
              enqueueCallbacks('create', [resolve, reject]);
              const message: OrtWasmMessage = {type: 'create', in : {model, options: {...options}}};
              const transferable: Transferable[] = [];
              if (model instanceof Uint8Array) {
                transferable.push(model.buffer);
              }
              proxyWorker!.postMessage(message, transferable);
            });
          } else {
            return core.createSession(model, options);
          }
        };

export const releaseSession = async(sessionId: number): Promise<void> => {
  if (!BUILD_DEFS.DISABLE_WASM_PROXY && isProxy()) {
    ensureWorker();
    return new Promise<void>((resolve, reject) => {
      enqueueCallbacks('release', [resolve, reject]);
      const message: OrtWasmMessage = {type: 'release', in : sessionId};
      proxyWorker!.postMessage(message);
    });
  } else {
    core.releaseSession(sessionId);
  }
};

export const run = async(
    sessionId: number, inputIndices: number[], inputs: TensorMetadata[], outputIndices: number[],
    outputs: Array<TensorMetadata|null>, options: InferenceSession.RunOptions): Promise<TensorMetadata[]> => {
  if (!BUILD_DEFS.DISABLE_WASM_PROXY && isProxy()) {
    // check inputs location
    if (inputs.some(t => t[3] !== 'cpu')) {
      throw new Error('input tensor on GPU is not supported for proxy.');
    }
    // check outputs location
    if (outputs.some(t => t)) {
      throw new Error('pre-allocated output tensor is not supported for proxy.');
    }
    ensureWorker();
    return new Promise<SerializableTensorMetadata[]>((resolve, reject) => {
      enqueueCallbacks('run', [resolve, reject]);
      const serializableInputs = inputs as SerializableTensorMetadata[];  // every input is on CPU.
      const message: OrtWasmMessage =
          {type: 'run', in : {sessionId, inputIndices, inputs: serializableInputs, outputIndices, options}};
      proxyWorker!.postMessage(message, core.extractTransferableBuffers(serializableInputs));
    });
  } else {
    return core.run(sessionId, inputIndices, inputs, outputIndices, outputs, options);
  }
};

export const endProfiling = async(sessionId: number): Promise<void> => {
  if (!BUILD_DEFS.DISABLE_WASM_PROXY && isProxy()) {
    ensureWorker();
    return new Promise<void>((resolve, reject) => {
      enqueueCallbacks('end-profiling', [resolve, reject]);
      const message: OrtWasmMessage = {type: 'end-profiling', in : sessionId};
      proxyWorker!.postMessage(message);
    });
  } else {
    core.endProfiling(sessionId);
  }
};