fix(NcRichText)!: do not render non-resolved relative links

- still works: external links, internal absolute links, and internal relative links, that do have a router match for current app
- internal relative links without match (also ?query and #anchor) only render an inner text
- allow tel: and mail: to reduce breaking changes

Signed-off-by: Maksim Sukharev <antreesy.web@gmail.com>

Author: Antreesy

cypress/component/richtext.cy.ts

@@ -7,6 +7,8 @@
 // Reference tests: https://github.com/nextcloud-deps/CDMarkdownKit/tree/master/CDMarkdownKitTests
 
 import { mount } from 'cypress/vue2'
+import Vue from 'vue'
+import VueRouter from 'vue-router'
 import NcRichText from '../../src/components/NcRichText/NcRichText.vue'
 
 describe('NcRichText', () => {
@@ -402,34 +404,56 @@ describe('NcRichText', () => {
 		})
 
 		describe('links', () => {
+			const TestRouteComponent = {
+				template: '<div />',
+			}
+
+			const mountRichText = (text: string) => {
+				Vue.use(VueRouter)
+				const routes = [{ path: '/world', component: TestRouteComponent }]
+				const router = new VueRouter({
+					mode: 'history',
+					routes,
+				})
+
+				mount(NcRichText, {
+					propsData: {
+						text,
+						useMarkdown: true,
+					},
+					extensions: {
+						plugins: [router],
+					},
+					router,
+				})
+			}
+
 			const testLink = (key: string, { text, href = text, name = text }) => {
 				it(key, () => {
-					mount(NcRichText, {
-						propsData: {
-							text,
-							useMarkdown: true,
-						},
-					})
+					mountRichText(text)
 					cy.get('a').should('have.text', name)
 					cy.get('a').invoke('attr', 'href').should('eq', href)
 				})
 			}
 
 			testLink('autolink', { text: 'https://autolink.me' })
-			testLink('relative link', { text: '[hello](world)', href: 'world', name: 'hello' })
+			testLink('relative link', { text: '[hello](/world)', href: '/world', name: 'hello' })
 			testLink('absolute link', { text: '[hello](https://nextcloud.com)', href: 'https://nextcloud.com', name: 'hello' })
 			testLink('tel link', { text: '[hello](tel:+49123456789)', href: 'tel:+49123456789', name: 'hello' })
+			testLink('mailto link', { text: '[hello](mailto:+49123456789)', href: 'mailto:+49123456789', name: 'hello' })
 
-			it('no link to unknown protocols', () => {
-				mount(NcRichText, {
-					propsData: {
-						text: '[link](other:proto)',
-						useMarkdown: true,
-					},
+			const testNoLink = (key: string, { text, name = text }) => {
+				it(key, () => {
+					mountRichText(text)
+
+					cy.get('body').should('contain', name)
+					cy.get('a').should('not.exist')
 				})
-				cy.get('body').should('contain', name)
-				cy.get('a').should('not.exist')
-			})
+			}
+			testNoLink('no link to unknown protocols', { text: '[hello](other:proto)', name: 'hello' })
+			testNoLink('no link to unresolved relative link (by router)', { text: '[hello](world)', name: 'hello' })
+			testNoLink('no link to relative parameters', { text: '[hello](?parameters=1)', name: 'hello' })
+			testNoLink('no link to relative anchor', { text: '[hello](#anchor)', name: 'hello' })
 		})
 
 		describe('multiline code', () => {

src/components/NcRichText/NcRichText.vue

@@ -320,6 +320,7 @@ import { RouterLink } from 'vue-router'
 import NcCheckboxRadioSwitch from '../NcCheckboxRadioSwitch/NcCheckboxRadioSwitch.vue'
 import NcReferenceList from './NcReferenceList.vue'
 import NcRichTextCopyButton from './NcRichTextCopyButton.vue'
+import NcRichTextExternalLink from './NcRichTextExternalLink.vue'
 import GenRandomId from '../../utils/GenRandomId.js'
 import { getRoute, remarkAutolink } from './autolink.js'
 import { prepareTextNode, remarkPlaceholder } from './placeholder.js'
@@ -556,6 +557,7 @@ export default {
 							if (tag === 'a') {
 								const route = getRoute(this.$router, attrs.attrs.href)
 								if (route) {
+									// Resolved link to this app; render RouterLink
 									delete attrs.attrs.href
 									delete attrs.attrs.target
 
@@ -566,6 +568,18 @@ export default {
 										},
 									}, children)
 								}
+
+								const isAllowedScheme = /^(https?:\/\/|tel:|mailto:)/.test(attrs.attrs.href)
+								if (isAllowedScheme) {
+									// External link; render normally, open in the new tab
+									attrs.attrs.href = attrs.attrs.href.trim()
+									return h(NcRichTextExternalLink, attrs, children)
+								} else {
+									// Unresolved relative link that does not belong to this app; render only children
+									delete attrs.attrs.href
+									delete attrs.attrs.target
+									return h('span', attrs, children)
+								}
 							}
 
 							return h(tag, attrs, children)