<script lang="ts" setup>
import type { Options as MarkdownOptions } from 'markdown-it'
import Markdown from 'markdown-it'
import { full as emoji } from 'markdown-it-emoji'
import markdownLink from 'markdown-it-link-attributes'
import markdownTaskLists from 'markdown-it-task-lists'
import { computed, ref } from 'vue'
import xss, { whiteList } from 'xss'

import { toggleCheckbox, serializeAttr } from './utils'

interface IImage {
	id: string | number
	url: string
}

interface Options {
	markdown: MarkdownOptions
	linkAttributes: markdownLink.Config
	tasklists: markdownTaskLists.Config
}

interface MarkdownProps {
	content?: string | null
	withMultiBreaks?: boolean
	images?: IImage[]
	loading?: boolean
	loadingBlocks?: number
	loadingRows?: number
	theme?: string
	options?: Options
}

const props = withDefaults(defineProps<MarkdownProps>(), {
	content: '',
	withMultiBreaks: false,
	images: () => [],
	loading: false,
	loadingBlocks: 2,
	loadingRows: 3,
	theme: 'markdown',
	options: () => ({
		markdown: {
			html: false,
			linkify: true,
			typographer: true,
			breaks: true
		},
		linkAttributes: {
			attrs: {
				target: '_blank',
				rel: 'noopener'
			}
		},
		tasklists: {
			enabled: true,
			label: true,
			labelAfter: false
		}
	})
})

const editor = ref<HTMLDivElement | undefined>(undefined)

const { options } = props
const md = new Markdown(options.markdown)
	.use(markdownLink, options.linkAttributes)
	.use(emoji)
	.use(markdownTaskLists, options.tasklists)

const xssWhiteList = {
	...whiteList,
	label: ['class', 'for'],
	iframe: ['width', 'height', 'src', 'title', 'frameborder', 'allow', 'referrerpolicy']
}

const htmlContent = computed(() => {
	if (!props.content) {
		return ''
	}

	const imageUrls: { [key: string]: string } = {}
	if (props.images) {
		props.images.forEach((image: IImage) => {
			if (!image) {
				// Happens if an image got deleted but the workflow
				// still has a reference to it
				return
			}
			imageUrls[image.id] = image.url
		})
	}

	const fileIdRegex = new RegExp('fileId:([0-9]+)')
	let contentToRender = props.content
	if (props.withMultiBreaks) {
		contentToRender = contentToRender.replaceAll('\n\n', '\n&nbsp;\n')
	}
	const html = md.render(contentToRender)

	const safeHtml = xss(html, {
		onTagAttr(tag, name, value) {
			if (tag === 'img' && name === 'src') {
				if (value.match(fileIdRegex)) {
					const id = value.split('fileId:')[1]
					const imageUrl = imageUrls[id]
					if (!imageUrl) {
						return ''
					}
					return serializeAttr(tag, name, imageUrl)
				}
				// Only allow http requests to supported image files from the `static` directory
				const isImageFile = value.split('#')[0].match(/\.(jpeg|jpg|gif|png|webp)$/) !== null
				const isStaticImageFile = isImageFile && value.startsWith('/static/')
				if (!value.startsWith('https://') && !isStaticImageFile) {
					return ''
				}
			}
			// Return nothing, means keep the default handling measure
			return
		},
		onTag(tag, code) {
			if (tag === 'img' && code.includes('alt="workflow-screenshot"')) {
				return ''
			}
			// return nothing, keep tag
			return
		},
		onIgnoreTag(tag, tagHTML) {
			// Allow checkboxes
			if (tag === 'input' && tagHTML.includes('type="checkbox"')) {
				return tagHTML
			}
			return
		},
		whiteList: xssWhiteList
	})

	return safeHtml
})

const emit = defineEmits<{
	'markdown-click': [link: HTMLAnchorElement, e: MouseEvent]
	'update-content': [content: string]
}>()

const onClick = (event: MouseEvent) => {
	let clickedLink: HTMLAnchorElement | null = null

	if (event.target instanceof HTMLAnchorElement) {
		clickedLink = event.target
	}

	if (event.target instanceof HTMLElement && event.target.matches('a *')) {
		const parentLink = event.target.closest('a')
		if (parentLink) {
			clickedLink = parentLink
		}
	}
	if (clickedLink) {
		emit('markdown-click', clickedLink, event)
	}
}

// Handle checkbox changes
const onChange = async (event: Event) => {
	if (event.target instanceof HTMLInputElement && event.target.type === 'checkbox') {
		const checkboxes = editor.value?.querySelectorAll('input[type="checkbox"]')
		if (checkboxes) {
			// Get the index of the checkbox that was clicked
			const index = Array.from(checkboxes).indexOf(event.target)
			if (index !== -1) {
				onCheckboxChange(index)
			}
		}
	}
}

const onMouseDown = (event: MouseEvent) => {
	// Mouse down on input fields is caught by node view handlers
	// which prevents checking them, this will prevent that
	if (event.target instanceof HTMLInputElement) {
		event.stopPropagation()
	}
}

// Update markdown when checkbox state changes
const onCheckboxChange = (index: number) => {
	const currentContent = props.content
	if (!currentContent) {
		return
	}

	// We are using index to connect the checkbox with the corresponding line in the markdown
	const newContent = toggleCheckbox(currentContent, index)
	emit('update-content', newContent)
}
</script>

<template>
	<div class="markdown">
		<!-- eslint-disable vue/no-v-html -->
		<div
			v-if="!loading"
			ref="editor"
			:class="$style[theme]"
			@click="onClick"
			@mousedown="onMouseDown"
			@change="onChange"
			v-html="htmlContent"
		/>
		<!-- eslint-enable vue/no-v-html -->
		<div v-else :class="$style.markdown">
			<div v-for="(_, index) in loadingBlocks" :key="index" v-loading="loading">
				<div :class="$style.spacer" />
			</div>
		</div>
	</div>
</template>

<style lang="less" module>
.markdown {
	color: var(--color--text);

	* {
		font-size: var(--font-size--md);
		line-height: var(--line-height--xl);
	}

	h1,
	h2,
	h3,
	h4 {
		margin-bottom: var(--spacing--sm);
		font-size: var(--font-size--md);
		font-weight: var(--font-weight--bold);
	}

	h3,
	h4 {
		font-weight: var(--font-weight--bold);
	}

	p,
	span {
		margin-bottom: var(--spacing--sm);
	}

	ul,
	ol {
		margin-bottom: var(--spacing--sm);
		padding-left: var(--spacing--md);

		li {
			margin-top: 0.25em;
		}
	}

	pre > code {
		background-color: var(--color--background);
		color: var(--color--text--shade-1);
	}

	li > code,
	p > code {
		padding: 0 var(--spacing--4xs);
		color: var(--color--text--shade-1);
		background-color: var(--color--background);
	}

	.label {
		color: var(--color--text);
	}

	img {
		max-width: 100%;
		border-radius: var(--radius--lg);
	}

	blockquote {
		padding-left: 10px;
		font-style: italic;
		border-left: var(--border-color) 2px solid;
	}
}

input[type='checkbox'] {
	accent-color: var(--color--primary);
}

input[type='checkbox'] + label {
	cursor: pointer;
}

.sticky {
	color: var(--sticky--color--text);
	overflow-wrap: break-word;

	h1,
	h2,
	h3,
	h4,
	h5,
	h6 {
		color: var(--sticky--color--text);
	}

	h1,
	h2,
	h3,
	h4 {
		margin-bottom: var(--spacing--2xs);
		font-weight: var(--font-weight--bold);
		line-height: var(--line-height--lg);
	}

	h1 {
		font-size: 36px;
	}

	h2 {
		font-size: 24px;
	}

	h3,
	h4,
	h5,
	h6 {
		font-size: var(--font-size--md);
	}

	p {
		margin-bottom: var(--spacing--2xs);
		font-size: var(--font-size--sm);
		font-weight: var(--font-weight--regular);
		line-height: var(--line-height--lg);
	}

	ul,
	ol {
		margin-bottom: var(--spacing--2xs);
		padding-left: var(--spacing--md);

		li {
			margin-top: 0.25em;
			font-size: var(--font-size--sm);
			font-weight: var(--font-weight--regular);
			line-height: var(--line-height--md);
		}

		&:has(input[type='checkbox']) {
			list-style-type: none;
			padding-left: var(--spacing--5xs);
		}
	}

	pre > code {
		background-color: var(--sticky--code--color--background);
		color: var(--sticky--code--color--text);
	}

	pre > code,
	li > code,
	p > code {
		color: var(--sticky--code--color--text);
	}

	a {
		&:hover {
			text-decoration: underline;
		}
	}

	img {
		object-fit: contain;
		margin-top: var(--spacing--xs);
		margin-bottom: var(--spacing--2xs);

		&[src*='#full-width'] {
			width: 100%;
		}
	}
}

.sticky,
.markdown {
	pre {
		margin-bottom: var(--spacing--sm);
		display: grid;
	}

	pre > code {
		display: block;
		padding: var(--spacing--sm);
		overflow-x: auto;
	}

	iframe {
		aspect-ratio: 16/9 auto;
	}

	summary {
		cursor: pointer;
	}
}

.spacer {
	margin: var(--spacing--2xl);
}
</style>
