source: main/trunk/model-interfaces-dev/atea/ocr/src/js/OcrService.js@ 35734

/**
 * @file Defines components that are used to interact with the OCR servlet.
 * @author Carl Stephens
 * @module
 */

import { log } from "./Util"

export class OcrError extends Error
{
    /**
     * Initializes a new instance of the {@link OcrError} object.
     *
     * @param {Number | undefined} statusCode The HTTP status code of the error.
     * @param {String | undefined} message The status message.
     * @param {String | null} fileName The file on which the OCR process failed.
     */
    constructor(message = undefined, fileName = null, statusCode = -1)
    {
        super(message);

        /** @type {String | null} The name of the file that the OCR error occured on. */
        this.fileName = fileName;

        /** @type {Number | undefined} The status code returned by the API when the error was generated. */
        this.statusCode = statusCode;
    }
}

export class OcrOptions
{
    /**
     * Initializes a new instance of the {@link OcrOptions} object.
     * @param {Boolean} layoutDetection Whether or not to enable automatic layout detection.
     */
    constructor(layoutDetection)
    {
        this.layoutDetection = layoutDetection;
    }
}

/**
 * A service that performs requests to the OCR API.
 */
export default class OcrService
{
    constructor()
    {
        /** @type {String} The URL to which query POST requests should be made. */
        if (process.env.NODE_ENV !== "production") {
            this.queryUrl = "//localhost:8383/gs3-atea-ocr/tesseract";
        }
        else {
            this.queryUrl = "/gs3-atea-ocr/tesseract";
        }
    }

    // TODO: Needs to allow blobs, and take file name
    /**
     * Makes an OCR request.
     * @param {{image: File, options: OcrOptions}[]} images The image set to perform OCR on.
     * @returns {Promise<{key: String, fileName: String, text: String}[]>} A JSON list of the recognised text.
     */
    async run(images)
    {
        const queryUrl = this.queryUrl;

        try
        {
            const options = {};
            const formData = new FormData();

            for (let i = 0; i < images.length; i++)
            {
                const element = images[i];
                const name = i + element.image.name;

                options[name] = element.options;
                formData.append(name, element.image, element.image.name);
            }

            formData.append("options", JSON.stringify(options));

            const response = await fetch(
                queryUrl,
                {
                    method: "POST",
                    body: formData
                }
            );

            if (!response.ok)
            {
                log(`OCR failed  with status ${response.status} and message ${response.statusText}`, "error");
                throw new OcrError(response.statusText, null, response.status);
            }

            return await response.json();
        }
        catch (e)
        {
            log(`OCR failed with reason ${e}`, "error");
            throw new OcrError("Unknown", null, null)
        }
    }
}