scratch-vm/src/virtual-machine.js

const EventEmitter = require('events');
const util = require('util');

const log = require('./util/log');
const Runtime = require('./engine/runtime');
const ScratchStorage = require('scratch-storage');
const sb2import = require('./import/sb2import');
const StringUtil = require('./util/string-util');

const loadCostume = require('./import/load-costume.js');
const loadSound = require('./import/load-sound.js');

const RESERVED_NAMES = ['_mouse_', '_stage_', '_edge_', '_myself_', '_random_'];

const AssetType = ScratchStorage.AssetType;

/**
 * Handles connections between blocks, stage, and extensions.
 * @constructor
 */
const VirtualMachine = function () {
    const instance = this;
    // Bind event emitter and runtime to VM instance
    EventEmitter.call(instance);
    /**
     * VM runtime, to store blocks, I/O devices, sprites/targets, etc.
     * @type {!Runtime}
     */
    instance.runtime = new Runtime();
    /**
     * The "currently editing"/selected target ID for the VM.
     * Block events from any Blockly workspace are routed to this target.
     * @type {!string}
     */
    instance.editingTarget = null;
    // Runtime emits are passed along as VM emits.
    instance.runtime.on(Runtime.SCRIPT_GLOW_ON, glowData => {
        instance.emit(Runtime.SCRIPT_GLOW_ON, glowData);
    });
    instance.runtime.on(Runtime.SCRIPT_GLOW_OFF, glowData => {
        instance.emit(Runtime.SCRIPT_GLOW_OFF, glowData);
    });
    instance.runtime.on(Runtime.BLOCK_GLOW_ON, glowData => {
        instance.emit(Runtime.BLOCK_GLOW_ON, glowData);
    });
    instance.runtime.on(Runtime.BLOCK_GLOW_OFF, glowData => {
        instance.emit(Runtime.BLOCK_GLOW_OFF, glowData);
    });
    instance.runtime.on(Runtime.PROJECT_RUN_START, () => {
        instance.emit(Runtime.PROJECT_RUN_START);
    });
    instance.runtime.on(Runtime.PROJECT_RUN_STOP, () => {
        instance.emit(Runtime.PROJECT_RUN_STOP);
    });
    instance.runtime.on(Runtime.VISUAL_REPORT, visualReport => {
        instance.emit(Runtime.VISUAL_REPORT, visualReport);
    });
    instance.runtime.on(Runtime.SPRITE_INFO_REPORT, spriteInfo => {
        instance.emit(Runtime.SPRITE_INFO_REPORT, spriteInfo);
    });

    this.blockListener = this.blockListener.bind(this);
    this.flyoutBlockListener = this.flyoutBlockListener.bind(this);
};

/**
 * Inherit from EventEmitter
 */
util.inherits(VirtualMachine, EventEmitter);

/**
 * Start running the VM - do this before anything else.
 */
VirtualMachine.prototype.start = function () {
    this.runtime.start();
};

/**
 * "Green flag" handler - start all threads starting with a green flag.
 */
VirtualMachine.prototype.greenFlag = function () {
    this.runtime.greenFlag();
};

/**
 * Set whether the VM is in "turbo mode."
 * When true, loops don't yield to redraw.
 * @param {boolean} turboModeOn Whether turbo mode should be set.
 */
VirtualMachine.prototype.setTurboMode = function (turboModeOn) {
    this.runtime.turboMode = !!turboModeOn;
};

/**
 * Set whether the VM is in 2.0 "compatibility mode."
 * When true, ticks go at 2.0 speed (30 TPS).
 * @param {boolean} compatibilityModeOn Whether compatibility mode is set.
 */
VirtualMachine.prototype.setCompatibilityMode = function (compatibilityModeOn) {
    this.runtime.setCompatibilityMode(!!compatibilityModeOn);
};

/**
 * Stop all threads and running activities.
 */
VirtualMachine.prototype.stopAll = function () {
    this.runtime.stopAll();
};

/**
 * Clear out current running project data.
 */
VirtualMachine.prototype.clear = function () {
    this.runtime.dispose();
    this.editingTarget = null;
    this.emitTargetsUpdate();
};

/**
 * Get data for playground. Data comes back in an emitted event.
 */
VirtualMachine.prototype.getPlaygroundData = function () {
    const instance = this;
    // Only send back thread data for the current editingTarget.
    const threadData = this.runtime.threads.filter(thread => thread.target === instance.editingTarget);
    // Remove the target key, since it's a circular reference.
    const filteredThreadData = JSON.stringify(threadData, (key, value) => {
        if (key === 'target') return;
        return value;
    }, 2);
    this.emit('playgroundData', {
        blocks: this.editingTarget.blocks,
        threads: filteredThreadData
    });
};

/**
 * Post I/O data to the virtual devices.
 * @param {?string} device Name of virtual I/O device.
 * @param {object} data Any data object to post to the I/O device.
 */
VirtualMachine.prototype.postIOData = function (device, data) {
    if (this.runtime.ioDevices[device]) {
        this.runtime.ioDevices[device].postData(data);
    }
};

/**
 * Load a project from a Scratch 2.0 JSON representation.
 * @param {?string} json JSON string representing the project.
 */
VirtualMachine.prototype.loadProject = function (json) {
    this.clear();
    // @todo: Handle other formats, e.g., Scratch 1.4, Scratch 3.0.
    sb2import(json, this.runtime);
    // Select the first target for editing, e.g., the first sprite.
    this.editingTarget = this.runtime.targets[1];
    // Update the VM user's knowledge of targets and blocks on the workspace.
    this.emitTargetsUpdate();
    this.emitWorkspaceUpdate();
    this.runtime.setEditingTarget(this.editingTarget);
};

/**
 * Load a project from the Scratch web site, by ID.
 * @param {string} id - the ID of the project to download, as a string.
 */
VirtualMachine.prototype.downloadProjectId = function (id) {
    if (!this.runtime.storage) {
        log.error('No storage module present; cannot load project: ', id);
        return;
    }
    const vm = this;
    const promise = this.runtime.storage.load(AssetType.Project, id);
    promise.then(projectAsset => {
        vm.loadProject(projectAsset.decodeText());
    });
};

/**
 * Add a single sprite from the "Sprite2" (i.e., SB2 sprite) format.
 * @param {string} json JSON string representing the sprite.
 */
VirtualMachine.prototype.addSprite2 = function (json) {
    // Select new sprite.
    this.editingTarget = sb2import(json, this.runtime, true);
    // Update the VM user's knowledge of targets and blocks on the workspace.
    this.emitTargetsUpdate();
    this.emitWorkspaceUpdate();
    this.runtime.setEditingTarget(this.editingTarget);
};

/**
 * Add a costume to the current editing target.
 * @param {string} md5ext - the MD5 and extension of the costume to be loaded.
 * @param {!object} costumeObject Object representing the costume.
 * @property {int} skinId - the ID of the costume's render skin, once installed.
 * @property {number} rotationCenterX - the X component of the costume's origin.
 * @property {number} rotationCenterY - the Y component of the costume's origin.
 * @property {number} [bitmapResolution] - the resolution scale for a bitmap costume.
 */
VirtualMachine.prototype.addCostume = function (md5ext, costumeObject) {
    loadCostume(md5ext, costumeObject, this.runtime).then(() => {
        this.editingTarget.sprite.costumes.push(costumeObject);
        this.editingTarget.setCostume(
            this.editingTarget.sprite.costumes.length - 1
        );
    });
};

/**
 * Add a sound to the current editing target.
 * @param {!object} soundObject Object representing the costume.
 * @returns {?Promise} - a promise that resolves when the sound has been decoded and added
 */
VirtualMachine.prototype.addSound = function (soundObject) {
    return loadSound(soundObject, this.runtime).then(() => {
        this.editingTarget.sprite.sounds.push(soundObject);
        this.emitTargetsUpdate();
    });
};

/**
 * Add a backdrop to the stage.
 * @param {string} md5ext - the MD5 and extension of the backdrop to be loaded.
 * @param {!object} backdropObject Object representing the backdrop.
 * @property {int} skinId - the ID of the backdrop's render skin, once installed.
 * @property {number} rotationCenterX - the X component of the backdrop's origin.
 * @property {number} rotationCenterY - the Y component of the backdrop's origin.
 * @property {number} [bitmapResolution] - the resolution scale for a bitmap backdrop.
 */
VirtualMachine.prototype.addBackdrop = function (md5ext, backdropObject) {
    loadCostume(md5ext, backdropObject, this.runtime).then(() => {
        const stage = this.runtime.getTargetForStage();
        stage.sprite.costumes.push(backdropObject);
        stage.setCostume(stage.sprite.costumes.length - 1);
    });
};

/**
 * Rename a sprite.
 * @param {string} targetId ID of a target whose sprite to rename.
 * @param {string} newName New name of the sprite.
 */
VirtualMachine.prototype.renameSprite = function (targetId, newName) {
    const target = this.runtime.getTargetById(targetId);
    if (target) {
        if (!target.isSprite()) {
            throw new Error('Cannot rename non-sprite targets.');
        }
        const sprite = target.sprite;
        if (!sprite) {
            throw new Error('No sprite associated with this target.');
        }
        if (newName && RESERVED_NAMES.indexOf(newName) === -1) {
            const names = this.runtime.targets
                .filter(runtimeTarget => runtimeTarget.isSprite())
                .map(runtimeTarget => runtimeTarget.sprite.name);

            sprite.name = StringUtil.unusedName(newName, names);
        }
        this.emitTargetsUpdate();
    } else {
        throw new Error('No target with the provided id.');
    }
};

/**
 * Delete a sprite and all its clones.
 * @param {string} targetId ID of a target whose sprite to delete.
 */
VirtualMachine.prototype.deleteSprite = function (targetId) {
    const target = this.runtime.getTargetById(targetId);
    if (target) {
        if (!target.isSprite()) {
            throw new Error('Cannot delete non-sprite targets.');
        }
        const sprite = target.sprite;
        if (!sprite) {
            throw new Error('No sprite associated with this target.');
        }
        const currentEditingTarget = this.editingTarget;
        for (let i = 0; i < sprite.clones.length; i++) {
            const clone = sprite.clones[i];
            this.runtime.stopForTarget(sprite.clones[i]);
            this.runtime.disposeTarget(sprite.clones[i]);
            // Ensure editing target is switched if we are deleting it.
            if (clone === currentEditingTarget) {
                this.setEditingTarget(this.runtime.targets[0].id);
            }
        }
        // Sprite object should be deleted by GC.
        this.emitTargetsUpdate();
    } else {
        throw new Error('No target with the provided id.');
    }
};

/**
 * Set the audio engine for the VM/runtime
 * @param {!AudioEngine} audioEngine The audio engine to attach
 */
VirtualMachine.prototype.attachAudioEngine = function (audioEngine) {
    this.runtime.attachAudioEngine(audioEngine);
};

/**
 * Set the renderer for the VM/runtime
 * @param {!RenderWebGL} renderer The renderer to attach
 */
VirtualMachine.prototype.attachRenderer = function (renderer) {
    this.runtime.attachRenderer(renderer);
};

/**
 * Set the storage module for the VM/runtime
 * @param {!ScratchStorage} storage The storage module to attach
 */
VirtualMachine.prototype.attachStorage = function (storage) {
    this.runtime.attachStorage(storage);
};

/**
 * Handle a Blockly event for the current editing target.
 * @param {!Blockly.Event} e Any Blockly event.
 */
VirtualMachine.prototype.blockListener = function (e) {
    if (this.editingTarget) {
        this.editingTarget.blocks.blocklyListen(e, this.runtime);
    }
};

/**
 * Handle a Blockly event for the flyout.
 * @param {!Blockly.Event} e Any Blockly event.
 */
VirtualMachine.prototype.flyoutBlockListener = function (e) {
    this.runtime.flyoutBlocks.blocklyListen(e, this.runtime);
};

/**
 * Set an editing target. An editor UI can use this function to switch
 * between editing different targets, sprites, etc.
 * After switching the editing target, the VM may emit updates
 * to the list of targets and any attached workspace blocks
 * (see `emitTargetsUpdate` and `emitWorkspaceUpdate`).
 * @param {string} targetId Id of target to set as editing.
 */
VirtualMachine.prototype.setEditingTarget = function (targetId) {
    // Has the target id changed? If not, exit.
    if (targetId === this.editingTarget.id) {
        return;
    }
    const target = this.runtime.getTargetById(targetId);
    if (target) {
        this.editingTarget = target;
        // Emit appropriate UI updates.
        this.emitTargetsUpdate();
        this.emitWorkspaceUpdate();
        this.runtime.setEditingTarget(target);
    }
};

/**
 * Emit metadata about available targets.
 * An editor UI could use this to display a list of targets and show
 * the currently editing one.
 */
VirtualMachine.prototype.emitTargetsUpdate = function () {
    this.emit('targetsUpdate', {
        // [[target id, human readable target name], ...].
        targetList: this.runtime.targets.filter(target =>
            // Don't report clones.
             !target.hasOwnProperty('isOriginal') || target.isOriginal).map(target => target.toJSON()),
        // Currently editing target id.
        editingTarget: this.editingTarget ? this.editingTarget.id : null
    });
};

/**
 * Emit an Blockly/scratch-blocks compatible XML representation
 * of the current editing target's blocks.
 */
VirtualMachine.prototype.emitWorkspaceUpdate = function () {
    this.emit('workspaceUpdate', {
        xml: this.editingTarget.blocks.toXML()
    });
};

/**
 * Get a target id for a drawable id. Useful for interacting with the renderer
 * @param {int} drawableId The drawable id to request the target id for
 * @returns {?string} The target id, if found. Will also be null if the target found is the stage.
 */
VirtualMachine.prototype.getTargetIdForDrawableId = function (drawableId) {
    const target = this.runtime.getTargetByDrawableId(drawableId);
    if (target && target.hasOwnProperty('id') && target.hasOwnProperty('isStage') && !target.isStage) {
        return target.id;
    }
    return null;
};

/**
 * Put a target into a "drag" state, during which its X/Y positions will be unaffected
 * by blocks.
 * @param {string} targetId The id for the target to put into a drag state
 */
VirtualMachine.prototype.startDrag = function (targetId) {
    const target = this.runtime.getTargetById(targetId);
    if (target) {
        target.startDrag();
        this.setEditingTarget(target.id);
    }
};

/**
 * Remove a target from a drag state, so blocks may begin affecting X/Y position again
 * @param {string} targetId The id for the target to remove from the drag state
 */
VirtualMachine.prototype.stopDrag = function (targetId) {
    const target = this.runtime.getTargetById(targetId);
    if (target) target.stopDrag();
};

/**
 * Post/edit sprite info for the current editing target.
 * @param {object} data An object with sprite info data to set.
 */
VirtualMachine.prototype.postSpriteInfo = function (data) {
    this.editingTarget.postSpriteInfo(data);
};

module.exports = VirtualMachine;