greek-manifests/src/service/ManifestBuilder.js

'use strict';

import Manifest from '../iiif/Manifest.js';
import Sequence from '../iiif/Sequence.js';
import Canvas from '../iiif/Canvas.js';
import Image from '../iiif/Image.js';
import ManifestMetadata from '../iiif/Metadata.js';
import { parse, getCanvasLabel, getCanvasName } from './FilenameParser.js';
import { getImageList } from './ImageRepository.js';
import { TECH_NAMES } from '../constants.js';

/**
 * Builds a manifest object based on canvases
 * and available metadata
 * @module ManifestBuilder
 */

const IIIF_API_VERSION = process.env.IIIF_API_VERSION;
const BASE_URL = process.env.BASE_URL;
const IMAGE_SERVER_URL = process.env.IMAGE_SERVER_URL;

/**
 * Builds a Manifest object
 * @param {String} manifestId 
 * @returns {Object}
 */
export async function buildManifest(manifestId) {

	let manifest = new Manifest(IIIF_API_VERSION, BASE_URL);
	manifest.generateID(manifestId);
	manifest.generateLabel();

	const images = await getImageList(manifestId); 

	manifest = await populateCanvases(manifest, images, manifestId);

	manifest.setMetadata(
		createMetadata(
			manifest,
			images[0], // A single image filename is sufficient to extract metadata
		)
	);

    return manifest.toObject();
}

/**
 * Builds a Canvas object from route parameters
 * @param {String} manifestId 
 * @param {String} name The canvas name
 */
export async function buildCanvas(manifestId, name) {
	const manifest = new Manifest(IIIF_API_VERSION, BASE_URL);
	manifest.generateID(manifestId);
	let filename = await getImageName(name, manifestId);

	return createCanvas(manifest, filename);
}
/**
 * Create a canvas from an image filename
 * @param {Manifest} manifest 
 * @param {string} filename The image filename 
 * @returns {Canvas}
 */
async function createCanvas (manifest, filename) {
	let canvas = new Canvas(IIIF_API_VERSION, BASE_URL);
    const canvasName = getCanvasName(filename, manifest.technique);

	canvas.generateID(manifest.resourceId, canvasName.toLowerCase());
	canvas.label = getCanvasLabel(canvasName);

	let image = new Image(canvas.id);
	image.generateID(IMAGE_SERVER_URL, filename, manifest.technique);

	const imgSize = await getImageSize(image.id);
	image.setSize(imgSize.height, imgSize.width);

	canvas.setThumbnail(
		imgSize.thumb.height,
		imgSize.thumb.width,
		image.id
	);
	canvas.addImage(image);

	return canvas;
}
/**
 * @param {string} imageId The image's id as a URL to the image server
 * @returns {{width: number, height: number, thumb: {width: number, height: number}}}
 */
async function getImageSize(imageId) {
	let infoURL = imageId.replace(/full.*$/,'info.json');
	const res = await fetch(infoURL);

	let size = {};

	if (res.ok) {
		const infoJson = await res.json();
		const maxSize = infoJson.sizes[infoJson.sizes.length - 1];
		size.height = maxSize.height;
		size.width = maxSize.width;
		size.thumb = {
			width: infoJson.sizes[1].width,
			height: infoJson.sizes[1].height,
		}
	}

	return size;
}
/**
 * @param {Manifest} manifest The manifest object
 * @param {string[]} images List of image filenames from folder
 * @returns {Manifest}
 */
async function populateCanvases (manifest, images) {
	const sequence = new Sequence(BASE_URL);

	// There's only one sequence
	sequence.generateID(manifest.resourceId, 0);

	for (let img of images) {
		// Skip failing images (TODO log error to file)
		try {
			let canvas = await createCanvas(manifest, img);
			sequence.addCanvas(canvas);
		} catch (error) {
			console.error(error);
			console.log(`\nAffected image: ${img}`);
			continue;
		}
	}

	// Sort them according to their ID number... (cornice, colonna, ecc...)
	sequence.canvases.sort((a, b) => {
		const firstId = a['@id'].slice(a['@id'].lastIndexOf('/') + 1).replace(/[a-z]+/ig,'');
		const secondId = b['@id'].slice(b['@id'].lastIndexOf('/') + 1).replace(/[a-z]+/ig,'');
		return Number(firstId) - Number(secondId);
	});

	manifest.addSequence(sequence);

	return manifest;
}
/**
 * Get image name for given canvas
 * @todo Use regex in filter!!
 * @param {String} name The canvas name
 * @param {String} manifestId The manifest (resource) id
 * @returns {string}
 */
async function getImageName(name, manifestId) {
    const images = await getImageList(manifestId);

	// Adjust canvas name for HSI with PCA...
	if (/pc(1|3)/.test(name)) {
		name = name.replace(
			/pc((1|3))/,
			function (match, group1) {
				return `_HSI_PC${group1}`;
			}
		);
	}

	return images.filter(i => i.includes(name))[0];
}
/**
 * @param {Manifest} manifest The Manifest object
 * @param {string} imgFilename
 * @returns {ManifestMetadata}
 */
function createMetadata(manifest, imgFilename) {
	let metadata = parse(imgFilename, manifest.technique);
	metadata.technique = TECH_NAMES[manifest.technique];

	return new ManifestMetadata(metadata);
}