implement nip94

nip94.ts

@@ -0,0 +1,201 @@
+import { Event, EventTemplate } from './core'
+import { FileMetadata as FileMetadataKind } from './kinds.ts'
+
+/**
+ * Type definition for File Metadata as specified in NIP-94.
+ * This type is used to represent the metadata associated with a file sharing event (kind: 1063).
+ */
+export type FileMetadataObject = {
+  /**
+   * A description or caption for the file content.
+   */
+  content: string
+
+  /**
+   * The URL to download the file.
+   */
+  url: string
+
+  /**
+   * The MIME type of the file, in lowercase.
+   */
+  m: string
+
+  /**
+   * The SHA-256 hex-encoded string of the file.
+   */
+  x: string
+
+  /**
+   * The SHA-256 hex-encoded string of the original file, before any transformations done by the upload server.
+   */
+  ox: string
+
+  /**
+   * Optional: The size of the file in bytes.
+   */
+  size?: string
+
+  /**
+   * Optional: The dimensions of the file in pixels, in the format "<width>x<height>".
+   */
+  dim?: string
+
+  /**
+   * Optional: The URI to the magnet file.
+   */
+  magnet?: string
+
+  /**
+   * Optional: The torrent infohash.
+   */
+  i?: string
+
+  /**
+   * Optional: The blurhash string to show while the file is being loaded by the client.
+   */
+  blurhash?: string
+
+  /**
+   * Optional: The URL of the thumbnail image with the same aspect ratio as the original file.
+   */
+  thumb?: string
+
+  /**
+   * Optional: The URL of a preview image with the same dimensions as the original file.
+   */
+  image?: string
+
+  /**
+   * Optional: A text excerpt or summary of the file's content.
+   */
+  summary?: string
+
+  /**
+   * Optional: A description for accessibility, providing context or a brief description of the file.
+   */
+  alt?: string
+}
+
+/**
+ * Generates an event template based on a file metadata object.
+ *
+ * @param fileMetadata - The file metadata object.
+ * @returns The event template.
+ */
+export function generateEventTemplate(fileMetadata: FileMetadataObject): EventTemplate {
+  const eventTemplate: EventTemplate = {
+    content: fileMetadata.content,
+    created_at: Math.floor(Date.now() / 1000),
+    kind: FileMetadataKind,
+    tags: [
+      ['url', fileMetadata.url],
+      ['m', fileMetadata.m],
+      ['x', fileMetadata.x],
+      ['ox', fileMetadata.ox],
+    ],
+  }
+
+  if (fileMetadata.size) eventTemplate.tags.push(['size', fileMetadata.size])
+  if (fileMetadata.dim) eventTemplate.tags.push(['dim', fileMetadata.dim])
+  if (fileMetadata.i) eventTemplate.tags.push(['i', fileMetadata.i])
+  if (fileMetadata.blurhash) eventTemplate.tags.push(['blurhash', fileMetadata.blurhash])
+  if (fileMetadata.thumb) eventTemplate.tags.push(['thumb', fileMetadata.thumb])
+  if (fileMetadata.image) eventTemplate.tags.push(['image', fileMetadata.image])
+  if (fileMetadata.summary) eventTemplate.tags.push(['summary', fileMetadata.summary])
+  if (fileMetadata.alt) eventTemplate.tags.push(['alt', fileMetadata.alt])
+
+  return eventTemplate
+}
+
+/**
+ * Validates an event to ensure it is a valid file metadata event.
+ * @param event - The event to validate.
+ * @returns True if the event is valid, false otherwise.
+ */
+export function validateEvent(event: Event): boolean {
+  if (event.kind !== FileMetadataKind) return false
+
+  if (!event.content) return false
+
+  const requiredTags = ['url', 'm', 'x', 'ox'] as const
+  for (const tag of requiredTags) {
+    if (!event.tags.find(([t]) => t == tag)) return false
+  }
+
+  // validate optional size tag
+  const sizeTag = event.tags.find(([t]) => t == 'size')
+  if (sizeTag && isNaN(Number(sizeTag[1]))) return false
+
+  // validate optional dim tag
+  const dimTag = event.tags.find(([t]) => t == 'dim')
+  if (dimTag && !dimTag[1].match(/^\d+x\d+$/)) return false
+
+  return true
+}
+
+/**
+ * Parses an event and returns a file metadata object.
+ * @param event - The event to parse.
+ * @returns The file metadata object.
+ * @throws Error if the event is invalid.
+ */
+export function parseEvent(event: Event): FileMetadataObject {
+  if (!validateEvent(event)) {
+    throw new Error('Invalid event')
+  }
+
+  const fileMetadata: FileMetadataObject = {
+    content: event.content,
+    url: '',
+    m: '',
+    x: '',
+    ox: '',
+  }
+
+  for (const [tag, value] of event.tags) {
+    switch (tag) {
+      case 'url':
+        fileMetadata.url = value
+        break
+      case 'm':
+        fileMetadata.m = value
+        break
+      case 'x':
+        fileMetadata.x = value
+        break
+      case 'ox':
+        fileMetadata.ox = value
+        break
+      case 'size':
+        fileMetadata.size = value
+        break
+      case 'dim':
+        fileMetadata.dim = value
+        break
+      case 'magnet':
+        fileMetadata.magnet = value
+        break
+      case 'i':
+        fileMetadata.i = value
+        break
+      case 'blurhash':
+        fileMetadata.blurhash = value
+        break
+      case 'thumb':
+        fileMetadata.thumb = value
+        break
+      case 'image':
+        fileMetadata.image = value
+        break
+      case 'summary':
+        fileMetadata.summary = value
+        break
+      case 'alt':
+        fileMetadata.alt = value
+        break
+    }
+  }
+
+  return fileMetadata
+}