tauri-workspace/packages/api/src/core.ts

// Copyright 2019-2024 Tauri Programme within The Commons Conservancy
// SPDX-License-Identifier: Apache-2.0
// SPDX-License-Identifier: MIT

/**
 * Invoke your custom commands.
 *
 * This package is also accessible with `window.__TAURI__.tauri` when [`app.withGlobalTauri`](https://v2.tauri.app/reference/config/#withglobaltauri) in `tauri.conf.json` is set to `true`.
 * @module
 */

/**
 * Transforms a callback function to a string identifier that can be passed to the backend.
 * The backend uses the identifier to `eval()` the callback.
 *
 * @return A unique identifier associated with the callback function.
 *
 * @since 1.0.0
 */
function transformCallback<T = unknown>(
  callback?: (response: T) => void,
  once = false
): number {
  return window.__TAURI_INTERNALS__.transformCallback(callback, once)
}

class Channel<T = unknown> {
  id: number
  // @ts-expect-error field used by the IPC serializer
  private readonly __TAURI_CHANNEL_MARKER__ = true
  #onmessage: (response: T) => void = () => {
    // no-op
  }
  #nextMessageId = 0
  #pendingMessages: Record<string, T> = {}

  constructor() {
    this.id = transformCallback(
      ({ message, id }: { message: T; id: number }) => {
        // the id is used as a mechanism to preserve message order
        if (id === this.#nextMessageId) {
          this.#nextMessageId = id + 1
          this.#onmessage(message)

          // process pending messages
          const pendingMessageIds = Object.keys(this.#pendingMessages)
          if (pendingMessageIds.length > 0) {
            let nextId = id + 1
            for (const pendingId of pendingMessageIds.sort()) {
              // if we have the next message, process it
              if (parseInt(pendingId) === nextId) {
                // eslint-disable-next-line security/detect-object-injection
                const message = this.#pendingMessages[pendingId]
                // eslint-disable-next-line security/detect-object-injection
                delete this.#pendingMessages[pendingId]

                this.#onmessage(message)

                // move the id counter to the next message to check
                nextId += 1
              } else {
                // we do not have the next message, let's wait
                break
              }
            }
            this.#nextMessageId = nextId
          }
        } else {
          this.#pendingMessages[id.toString()] = message
        }
      }
    )
  }

  set onmessage(handler: (response: T) => void) {
    this.#onmessage = handler
  }

  get onmessage(): (response: T) => void {
    return this.#onmessage
  }

  toJSON(): string {
    return `__CHANNEL__:${this.id}`
  }
}

class PluginListener {
  plugin: string
  event: string
  channelId: number

  constructor(plugin: string, event: string, channelId: number) {
    this.plugin = plugin
    this.event = event
    this.channelId = channelId
  }

  async unregister(): Promise<void> {
    return invoke(`plugin:${this.plugin}|remove_listener`, {
      event: this.event,
      channelId: this.channelId
    })
  }
}

/**
 * Adds a listener to a plugin event.
 *
 * @returns The listener object to stop listening to the events.
 *
 * @since 2.0.0
 */
async function addPluginListener<T>(
  plugin: string,
  event: string,
  cb: (payload: T) => void
): Promise<PluginListener> {
  const handler = new Channel<T>()
  handler.onmessage = cb
  return invoke(`plugin:${plugin}|register_listener`, { event, handler }).then(
    () => new PluginListener(plugin, event, handler.id)
  )
}

type PermissionState = 'granted' | 'denied' | 'prompt' | 'prompt-with-rationale'

/**
 * Get permission state for a plugin.
 *
 * This should be used by plugin authors to wrap their actual implementation.
 */
async function checkPermissions<T>(plugin: string): Promise<T> {
  return invoke(`plugin:${plugin}|check_permissions`)
}

/**
 * Request permissions.
 *
 * This should be used by plugin authors to wrap their actual implementation.
 */
async function requestPermissions<T>(plugin: string): Promise<T> {
  return invoke(`plugin:${plugin}|request_permissions`)
}

/**
 * Command arguments.
 *
 * @since 1.0.0
 */
type InvokeArgs = Record<string, unknown> | number[] | ArrayBuffer | Uint8Array

/**
 * @since 2.0.0
 */
interface InvokeOptions {
  headers: Headers | Record<string, string>
}

/**
 * Sends a message to the backend.
 * @example
 * ```typescript
 * import { invoke } from '@tauri-apps/api/core';
 * await invoke('login', { user: 'tauri', password: 'poiwe3h4r5ip3yrhtew9ty' });
 * ```
 *
 * @param cmd The command name.
 * @param args The optional arguments to pass to the command.
 * @param options The request options.
 * @return A promise resolving or rejecting to the backend response.
 *
 * @since 1.0.0
 */
async function invoke<T>(
  cmd: string,
  args: InvokeArgs = {},
  options?: InvokeOptions
): Promise<T> {
  return window.__TAURI_INTERNALS__.invoke(cmd, args, options)
}

/**
 * Convert a device file path to an URL that can be loaded by the webview.
 * Note that `asset:` and `http://asset.localhost` must be added to [`app.security.csp`](https://v2.tauri.app/reference/config/#csp-1) in `tauri.conf.json`.
 * Example CSP value: `"csp": "default-src 'self' ipc: http://ipc.localhost; img-src 'self' asset: http://asset.localhost"` to use the asset protocol on image sources.
 *
 * Additionally, `"enable" : "true"` must be added to [`app.security.assetProtocol`](https://v2.tauri.app/reference/config/#assetprotocolconfig)
 * in `tauri.conf.json` and its access scope must be defined on the `scope` array on the same `assetProtocol` object.
 *
 * @param  filePath The file path.
 * @param  protocol The protocol to use. Defaults to `asset`. You only need to set this when using a custom protocol.
 * @example
 * ```typescript
 * import { appDataDir, join } from '@tauri-apps/api/path';
 * import { convertFileSrc } from '@tauri-apps/api/core';
 * const appDataDirPath = await appDataDir();
 * const filePath = await join(appDataDirPath, 'assets/video.mp4');
 * const assetUrl = convertFileSrc(filePath);
 *
 * const video = document.getElementById('my-video');
 * const source = document.createElement('source');
 * source.type = 'video/mp4';
 * source.src = assetUrl;
 * video.appendChild(source);
 * video.load();
 * ```
 *
 * @return the URL that can be used as source on the webview.
 *
 * @since 1.0.0
 */
function convertFileSrc(filePath: string, protocol = 'asset'): string {
  return window.__TAURI_INTERNALS__.convertFileSrc(filePath, protocol)
}

/**
 * A rust-backed resource stored through `tauri::Manager::resources_table` API.
 *
 * The resource lives in the main process and does not exist
 * in the Javascript world, and thus will not be cleaned up automatiacally
 * except on application exit. If you want to clean it up early, call {@linkcode Resource.close}
 *
 * @example
 * ```typescript
 * import { Resource, invoke } from '@tauri-apps/api/core';
 * export class DatabaseHandle extends Resource {
 *   static async open(path: string): Promise<DatabaseHandle> {
 *     const rid: number = await invoke('open_db', { path });
 *     return new DatabaseHandle(rid);
 *   }
 *
 *   async execute(sql: string): Promise<void> {
 *     await invoke('execute_sql', { rid: this.rid, sql });
 *   }
 * }
 * ```
 */
export class Resource {
  readonly #rid: number

  get rid(): number {
    return this.#rid
  }

  constructor(rid: number) {
    this.#rid = rid
  }

  /**
   * Destroys and cleans up this resource from memory.
   * **You should not call any method on this object anymore and should drop any reference to it.**
   */
  async close(): Promise<void> {
    return invoke('plugin:resources|close', {
      rid: this.rid
    })
  }
}

function isTauri(): boolean {
  return 'isTauri' in window && !!window.isTauri
}

export type { InvokeArgs, InvokeOptions }

export {
  transformCallback,
  Channel,
  PluginListener,
  addPluginListener,
  PermissionState,
  checkPermissions,
  requestPermissions,
  invoke,
  convertFileSrc,
  isTauri
}