@intres/azure-computer-vision/utilities/image-analysis-base.js

Node-red nodes for Microsoft Azure Computer Vision

const path = require('path');
const fs = require('fs');

class ImageAnalysisBase {
    #node;
    #key;
    #region;

    constructor(node, key, region) {
        this.#node = node;
        this.#key = key;
        this.#region = region;

        this.INPUT_MODE  = {
            file: 'file',
            url: 'url',
        };
    }

    /*********** Abstract method ***********/

    preProcess() {
        throw new Error('preProcess() must be implemented');
    }

    async analyzeInternal() {
        throw new Error('analyzeInternal() must be implemented');
    }

    getRegion() {
        return this.#region;
    }

    setStatus(status) {
        this.#node.status(status);
    }

    /*********** Concrete method ***********/

    checkInputMode({ inputMode, imageFilePath, imageUrl }) {
        if (inputMode === this.INPUT_MODE.url ) {
            if (!imageUrl) throw new Error('imageUrl must not be empty');
        } else {
            if (!imageFilePath || !path.isAbsolute(imageFilePath)) throw new Error('Image file path must be a string of an absolute path to local file system');
        }
    }

    async analyze(options) {
        // Test input mode
        this.checkInputMode(options);
        // Clean and check features for different services
        this.preProcess(options);

        let config, data;
        if (options.inputMode === this.INPUT_MODE.url) {
            config = {
                headers: {
                    "Content-Type": "application/json",
                    "Ocp-Apim-Subscription-Key": this.#key
                }
            }

            data = {
                "url": options.imageUrl
            }
        } else if (options.inputMode === this.INPUT_MODE.file) {
            config = {
                headers: {
                    "Content-Type": "application/octet-stream",
                    "Ocp-Apim-Subscription-Key": this.#key
                }
            }

            data = fs.readFileSync(options.imageFilePath);
            if (data.length === 0) throw new Error('The image file provided is empty, recognition aborted');
        } else {
            // For get-read-result
            config = {
                headers: {
                    "Ocp-Apim-Subscription-Key": this.#key
                }
            }
        }

        return this.analyzeInternal({
            ...options,
            config,
            data
        });
    }

    async run(options) {
        try {
            return await this.analyze(options);
        } catch (e) {
            const message = e?.response?.data?.error?.message || e.message;
            throw new Error(message);
        }
    }
}

module.exports = ImageAnalysisBase;