import { Root as HTMLRoot } from "hast"
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import { toString } from "hast-util-to-string"
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import { QuartzTransformerPlugin } from "../types"
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import { escapeHTML } from "../../util/escape"
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export interface Options {
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descriptionLength: number
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maxDescriptionLength: number
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replaceExternalLinks: boolean
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}
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const defaultOptions: Options = {
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descriptionLength: 150,
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maxDescriptionLength: 300,
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replaceExternalLinks: true,
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}
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const urlRegex = new RegExp(
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/(https?:\/\/)?(?<domain>([\da-z\.-]+)\.([a-z\.]{2,6})(:\d+)?)(?<path>[\/\w\.-]*)(\?[\/\w\.=&;-]*)?/,
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"g",
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)
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export const Description: QuartzTransformerPlugin<Partial<Options>> = (userOpts) => {
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const opts = { ...defaultOptions, ...userOpts }
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return {
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name: "Description",
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htmlPlugins() {
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return [
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() => {
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return async (tree: HTMLRoot, file) => {
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let frontMatterDescription = file.data.frontmatter?.description
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let text = escapeHTML(toString(tree))
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if (opts.replaceExternalLinks) {
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frontMatterDescription = frontMatterDescription?.replace(
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urlRegex,
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"$<domain>" + "$<path>",
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)
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text = text.replace(urlRegex, "$<domain>" + "$<path>")
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}
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if (frontMatterDescription) {
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file.data.description = frontMatterDescription
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file.data.text = text
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return
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}
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// otherwise, use the text content
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const desc = text
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const sentences = desc.replace(/\s+/g, " ").split(/\.\s/)
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let finalDesc = ""
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let sentenceIdx = 0
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// Add full sentences until we exceed the guideline length
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while (sentenceIdx < sentences.length) {
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const sentence = sentences[sentenceIdx]
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if (!sentence) break
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const currentSentence = sentence.endsWith(".") ? sentence : sentence + "."
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const nextLength = finalDesc.length + currentSentence.length + (finalDesc ? 1 : 0)
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// Add the sentence if we're under the guideline length
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// or if this is the first sentence (always include at least one)
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if (nextLength <= opts.descriptionLength || sentenceIdx === 0) {
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finalDesc += (finalDesc ? " " : "") + currentSentence
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sentenceIdx++
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} else {
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break
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}
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}
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// truncate to max length if necessary
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file.data.description =
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finalDesc.length > opts.maxDescriptionLength
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? finalDesc.slice(0, opts.maxDescriptionLength) + "..."
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: finalDesc
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file.data.text = text
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}
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},
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]
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},
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}
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}
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declare module "vfile" {
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interface DataMap {
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description: string
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text: string
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}
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}
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