Desktop: Fix import interop service (#1887)

* Revert "Revert "Desktop: Add ENEX to HTML export (#1795)""

This reverts commit 50b66cceca.

* Revert "Revert "Desktop, Cli: Fixed interop service so that it still allow auto-detecting importer based on format (required for Cli and for test units)""

This reverts commit c7c57ab2a5.

* Fix the .md importer

* Add comment re future refactor

* Rm importerClass for .md importer

* Fix EnexToMd module name

ReactNativeClient/lib/import-enex-html-gen.js

@@ -0,0 +1,170 @@
+const stringToStream = require('string-to-stream');
+const cleanHtml = require('clean-html');
+const resourceUtils = require('lib/resourceUtils.js');
+
+function addResourceTag(lines, resource, attributes) {
+	// Note: refactor to use Resource.markdownTag
+	if (!attributes.alt) attributes.alt = resource.title;
+	if (!attributes.alt) attributes.alt = resource.filename;
+	if (!attributes.alt) attributes.alt = '';
+
+	const src = `:/${resource.id}`;
+
+	if (resourceUtils.isImageMimeType(resource.mime)) {
+		lines.push(resourceUtils.imgElement({src, attributes}));
+	} else if (resource.mime === 'audio/x-m4a') {
+		/**
+		 * TODO: once https://github.com/laurent22/joplin/issues/1794 is resolved,
+		 * come back to this and make sure it works.
+		 */
+		lines.push(resourceUtils.audioElement({
+			src,
+			alt: attributes.alt,
+			id: resource.id,
+		}));
+	} else {
+		// TODO: figure out what other mime types can be handled more gracefully
+		lines.push(resourceUtils.attachmentElement({
+			src,
+			attributes,
+			id: resource.id,
+		}));
+	}
+
+	return lines;
+}
+
+function attributeToLowerCase(node) {
+	if (!node.attributes) return {};
+	let output = {};
+	for (let n in node.attributes) {
+		if (!node.attributes.hasOwnProperty(n)) continue;
+		output[n.toLowerCase()] = node.attributes[n];
+	}
+	return output;
+}
+
+function enexXmlToHtml_(stream, resources) {
+	let remainingResources = resources.slice();
+
+	const removeRemainingResource = id => {
+		for (let i = 0; i < remainingResources.length; i++) {
+			const r = remainingResources[i];
+			if (r.id === id) {
+				remainingResources.splice(i, 1);
+			}
+		}
+	};
+
+	return new Promise((resolve, reject) => {
+		const options = {};
+		const strict = false;
+		var saxStream = require('sax').createStream(strict, options);
+
+		let section = {
+			type: 'text',
+			lines: [],
+			parent: null,
+		};
+
+		saxStream.on('error', function(e) {
+			console.warn(e);
+			// reject(e);
+		});
+
+
+		saxStream.on('text', function(text) {
+			section.lines.push(text);
+		});
+
+		saxStream.on('opentag', function(node) {
+			const tagName = node.name.toLowerCase();
+			const attributesStr = resourceUtils.attributesToStr(node.attributes);
+
+			if (tagName === 'en-media') {
+				const nodeAttributes = attributeToLowerCase(node);
+				const hash = nodeAttributes.hash;
+
+				let resource = null;
+				for (let i = 0; i < resources.length; i++) {
+					let r = resources[i];
+					if (r.id == hash) {
+						resource = r;
+						removeRemainingResource(r.id);
+						break;
+					}
+				}
+
+				if (!resource) {
+					// TODO: Extract this duplicate of code in ./import-enex-md-gen.js
+					let found = false;
+					for (let i = 0; i < remainingResources.length; i++) {
+						let r = remainingResources[i];
+						if (!r.id) {
+							resource = Object.assign({}, r);
+							resource.id = hash;
+							remainingResources.splice(i, 1);
+							found = true;
+							break;
+						}
+					}
+
+					if (!found) {
+						reject(`Hash with no associated resource: ${hash}`);
+					}
+				}
+
+				// If the resource does not appear among the note's resources, it
+				// means it's an attachement. It will be appended along with the
+				// other remaining resources at the bottom of the markdown text.
+				if (resource && !!resource.id) {
+					section.lines = addResourceTag(section.lines, resource, nodeAttributes);
+				}
+			} else if (tagName == 'en-todo') {
+				section.lines.push('<input type="checkbox" onclick="return false;" />');
+			} else if (node.isSelfClosing) {
+				section.lines.push(`<${tagName}${attributesStr}>`);
+			} else {
+				section.lines.push(`<${tagName}${attributesStr} />`);
+			}
+		});
+
+		saxStream.on('closetag', function(n) {
+			const tagName = n ? n.toLowerCase() : n;
+			section.lines.push(`</${tagName}>`);
+		});
+
+		saxStream.on('attribute', function() {});
+
+		saxStream.on('end', function() {
+			resolve({
+				content: section,
+				resources: remainingResources,
+			});
+		});
+
+		stream.pipe(saxStream);
+	});
+}
+
+async function enexXmlToHtml(xmlString, resources, options = {}) {
+	const stream = stringToStream(xmlString);
+	let result = await enexXmlToHtml_(stream, resources, options);
+
+	try {
+		const preCleaning = result.content.lines.join(''); // xmlString
+		const final = await beautifyHtml(preCleaning);
+		return final.join('');
+	} catch (error) {
+		console.warn(error);
+	}
+}
+
+const beautifyHtml = (html) => {
+	return new Promise((resolve) => {
+		const options = {wrap: 0};
+		cleanHtml.clean(html, options, (...cleanedHtml) => resolve(cleanedHtml));
+	});
+};
+
+module.exports = {enexXmlToHtml};