1 files changed, 161 insertions, 0 deletions
diff --git a/apps/web/lib/opml.ts b/apps/web/lib/opml.ts
new file mode 100644
index 0000000..bd0c3a7
--- /dev/null
+++ b/apps/web/lib/opml.ts
@@ -0,0 +1,161 @@
+import type { Folder, Subscription } from "@/lib/types/subscription"
+
+function escapeXml(text: string): string {
+  return text
+    .replace(/&/g, "&amp;")
+    .replace(/</g, "&lt;")
+    .replace(/>/g, "&gt;")
+    .replace(/"/g, "&quot;")
+    .replace(/'/g, "&apos;")
+}
+
+export function generateOpml(
+  subscriptions: Subscription[],
+  folders: Folder[]
+): string {
+  const lines: string[] = [
+    '<?xml version="1.0" encoding="UTF-8"?>',
+    '<opml version="2.0">',
+    "  <head>",
+    "    <title>asa.news subscriptions</title>",
+    `    <dateCreated>${new Date().toUTCString()}</dateCreated>`,
+    "  </head>",
+    "  <body>",
+  ]
+
+  const folderMap = new Map<string, Folder>()
+
+  for (const folder of folders) {
+    folderMap.set(folder.folderIdentifier, folder)
+  }
+
+  const subscriptionsByFolder = new Map<string | null, Subscription[]>()
+
+  for (const subscription of subscriptions) {
+    const key = subscription.folderIdentifier
+    const existing = subscriptionsByFolder.get(key) ?? []
+    existing.push(subscription)
+    subscriptionsByFolder.set(key, existing)
+  }
+
+  const ungrouped = subscriptionsByFolder.get(null) ?? []
+
+  for (const subscription of ungrouped) {
+    const title = escapeXml(subscription.customTitle ?? subscription.feedTitle)
+    const xmlUrl = escapeXml(subscription.feedUrl)
+    lines.push(
+      `    <outline type="rss" text="${title}" title="${title}" xmlUrl="${xmlUrl}" />`
+    )
+  }
+
+  for (const folder of folders) {
+    const folderSubscriptions =
+      subscriptionsByFolder.get(folder.folderIdentifier) ?? []
+    const folderName = escapeXml(folder.name)
+    lines.push(`    <outline text="${folderName}" title="${folderName}">`)
+
+    for (const subscription of folderSubscriptions) {
+      const title = escapeXml(subscription.customTitle ?? subscription.feedTitle)
+      const xmlUrl = escapeXml(subscription.feedUrl)
+      lines.push(
+        `      <outline type="rss" text="${title}" title="${title}" xmlUrl="${xmlUrl}" />`
+      )
+    }
+
+    lines.push("    </outline>")
+  }
+
+  lines.push("  </body>")
+  lines.push("</opml>")
+
+  return lines.join("\n")
+}
+
+export interface ParsedOpmlFeed {
+  url: string
+  title: string
+}
+
+export interface ParsedOpmlGroup {
+  folderName: string | null
+  feeds: ParsedOpmlFeed[]
+}
+
+export function parseOpml(xmlString: string): ParsedOpmlGroup[] {
+  const parser = new DOMParser()
+  const document = parser.parseFromString(xmlString, "application/xml")
+  const parseError = document.querySelector("parsererror")
+
+  if (parseError) {
+    throw new Error("Invalid OPML file")
+  }
+
+  const body = document.querySelector("body")
+
+  if (!body) {
+    throw new Error("Invalid OPML: no body element")
+  }
+
+  const groups: ParsedOpmlGroup[] = []
+  const ungroupedFeeds: ParsedOpmlFeed[] = []
+  const topLevelOutlines = body.querySelectorAll(":scope > outline")
+
+  for (const outline of topLevelOutlines) {
+    const xmlUrl = outline.getAttribute("xmlUrl")
+
+    if (xmlUrl) {
+      ungroupedFeeds.push({
+        url: xmlUrl,
+        title:
+          outline.getAttribute("title") ??
+          outline.getAttribute("text") ??
+          xmlUrl,
+      })
+    } else {
+      const folderName =
+        outline.getAttribute("title") ?? outline.getAttribute("text")
+      const feeds: ParsedOpmlFeed[] = []
+      const childOutlines = outline.querySelectorAll(":scope > outline")
+
+      for (const child of childOutlines) {
+        const childXmlUrl = child.getAttribute("xmlUrl")
+
+        if (childXmlUrl) {
+          feeds.push({
+            url: childXmlUrl,
+            title:
+              child.getAttribute("title") ??
+              child.getAttribute("text") ??
+              childXmlUrl,
+          })
+        }
+      }
+
+      if (feeds.length > 0) {
+        groups.push({ folderName: folderName, feeds })
+      }
+    }
+  }
+
+  if (ungroupedFeeds.length > 0) {
+    groups.unshift({ folderName: null, feeds: ungroupedFeeds })
+  }
+
+  return groups
+}
+
+export function downloadOpml(
+  subscriptions: Subscription[],
+  folders: Folder[]
+): void {
+  const opmlContent = generateOpml(subscriptions, folders)
+  const blob = new Blob([opmlContent], { type: "application/xml" })
+  const url = URL.createObjectURL(blob)
+  const anchor = window.document.createElement("a")
+  anchor.href = url
+  anchor.download = "asa-news-subscriptions.opml"
+  window.document.body.appendChild(anchor)
+  anchor.click()
+  window.document.body.removeChild(anchor)
+  URL.revokeObjectURL(url)
+}