/**
 * @author n1474335 [n1474335@gmail.com]
 * @author mshwed [m@ttshwed.com]
 * @author Matt C [me@mitt.dev]
 * @copyright Crown Copyright 2019
 * @license Apache-2.0
 */

 import Operation from "../Operation.mjs";
 import OperationError from "../errors/OperationError.mjs";
 import { isImage } from "../lib/FileType.mjs";
 import { toBase64 } from "../lib/Base64.mjs";
 import { isWorkerEnvironment } from "../Utils.mjs";
 
 import { createWorker } from "tesseract.js";
 
 /**
  * Optical Character Recognition operation
  */
 class OpticalCharacterRecognition extends Operation {
 
     /**
      * OpticalCharacterRecognition constructor
      */
     constructor() {
         super();
 
         this.name = "Optical Character Recognition";
         this.module = "OCR";
         this.description = "Optical character recognition or optical character reader (OCR) is the mechanical or electronic conversion of images of typed, handwritten or printed text into machine-encoded text.<br><br>Supported image formats: png, jpg, bmp, pbm.";
         this.infoURL = "https://wikipedia.org/wiki/Optical_character_recognition";
         this.inputType = "ArrayBuffer";
         this.outputType = "string";
         this.args = [
             {
                 name: "Show confidence",
                 type: "boolean",
                 value: true
             },
             {
                 name: "Language",
                 type: "editableOptionShort",
                 value: [
                     { name: "Afrikaans", value: "afr" },
                     { name: "Arabic", value: "ara" },
                     { name: "Azerbaijani", value: "aze" },
                     { name: "Belarusian", value: "bel" },
                     { name: "Bengali", value: "ben" },
                     { name: "Bulgarian", value: "bul" },
                     { name: "Catalan", value: "cat" },
                     { name: "Czech", value: "ces" },
                     { name: "Chinese", value: "chi_sim" },
                     { name: "Traditional Chinese", value: "chi_tra" },
                     { name: "Cherokee", value: "chr" },
                     { name: "Danish", value: "dan" },
                     { name: "German", value: "deu" },
                     { name: "Greek", value: "ell" },
                     { name: "English", value: "eng" },
                     { name: "English (Old)", value: "enm" },
                     { name: "Internet Meme", value: "meme" },
                     { name: "Esperanto", value: "epo" },
                     { name: "Esperanto alternative", value: "epo_alt" },
                     { name: "Estonian", value: "est" },
                     { name: "Basque", value: "eus" },
                     { name: "Finnish", value: "fin" },
                     { name: "French", value: "fra" },
                     { name: "Frankish", value: "frk" },
                     { name: "French (Old)", value: "frm" },
                     { name: "Galician", value: "glg" },
                     { name: "Ancient Greek", value: "grc" },
                     { name: "Hebrew", value: "heb" },
                     { name: "Hindi", value: "hin" },
                     { name: "Croatian", value: "hrv" },
                     { name: "Hungarian", value: "hun" },
                     { name: "Indonesian", value: "ind" },
                     { name: "Icelandic", value: "isl" },
                     { name: "Italian", value: "ita" },
                     { name: "Italian (Old)", value: "ita_old" },
                     { name: "Japanese", value: "jpn" },
                     { name: "Kannada", value: "kan" },
                     { name: "Korean", value: "kor" },
                     { name: "Latvian", value: "lav" },
                     { name: "Lithuanian", value: "lit" },
                     { name: "Malayalam", value: "mal" },
                     { name: "Macedonian", value: "mkd" },
                     { name: "Maltese", value: "mlt" },
                     { name: "Malay", value: "msa" },
                     { name: "Dutch", value: "nld" },
                     { name: "Norwegian", value: "nor" },
                     { name: "Polish", value: "pol" },
                     { name: "Portuguese", value: "por" },
                     { name: "Romanian", value: "ron" },
                     { name: "Russian", value: "rus" },
                     { name: "Slovakian", value: "slk" },
                     { name: "Slovenian", value: "slv" },
                     { name: "Spanish", value: "spa" },
                     { name: "Old Spanish", value: "spa_old" },
                     { name: "Albanian", value: "sqi" },
                     { name: "Serbian (Latin)", value: "srp" },
                     { name: "Swahili", value: "swa" },
                     { name: "Swedish", value: "swe" },
                     { name: "Tamil", value: "tam" },
                     { name: "Telugu", value: "tel" },
                     { name: "Tagalog", value: "tgl" },
                     { name: "Thai", value: "tha" },
                     { name: "Turkish", value: "tur" },
                     { name: "Ukrainian", value: "ukr" },
                     { name: "Vietnamese", value: "vie" },
                 ],
                 defaultIndex: 14
             }
         ];
     }
 
     /**
      * @param {ArrayBuffer} input
      * @param {Object[]} args
      * @returns {string}
      */
     async run(input, args) {
         const [showConfidence, language] = args;
 
         if (!isWorkerEnvironment()) throw new OperationError("This operation only works in a browser");
 
         const type = isImage(input);
         if (!type) {
             throw new OperationError("Unsupported file type (supported: jpg,png,pbm,bmp) or no file provided\nOpen an image as input using the toolbar.");
         }
 
         try {
             self.sendStatusMessage("Spinning up Tesseract worker...");
             const image = `data:${type};base64,${toBase64(input)}`;
             const worker = createWorker({
                 logger: progress => {
                     if (isWorkerEnvironment()) {
                         self.sendStatusMessage(`Status: ${progress.status}${progress.status === "recognizing text" ? ` - ${(parseFloat(progress.progress)*100).toFixed(2)}%`: "" }`);
                     }
                 }
             });
             await worker.load();
             self.sendStatusMessage(`Loading ${language} language pack...`);
             await worker.loadLanguage(language);
             self.sendStatusMessage("Intialising Tesseract API...");
             await worker.initialize(language);
             self.sendStatusMessage("Finding text...");
             const result = await worker.recognize(image);
 
             if (showConfidence) {
                 return `Confidence: ${result.data.confidence}%\n\n${result.data.text}`;
             } else {
                 return result.data.text;
             }
         } catch (err) {
             throw new OperationError(`Error performing OCR on image. (${err})`);
         }
     }
 }
 
 export default OpticalCharacterRecognition;