Encode lastmod dates in engine_files

Apropos #177

Author: dfabulich

src/common/interface.ts

@@ -51,6 +51,7 @@ export interface ParchmentOptions extends Omit<GlkOteOptions, 'accept'> {
     theme_cookie: string,
     /** Whether to test the AsyncGlk GlkApi library */
     use_asyncglk?: TruthyOption,
+    engine_files?: {[key: string]: string}
 
     // Modules to pass to other modules
 

src/iplayif.com/app/src/front-page.ts

@@ -54,6 +54,7 @@ export default class FrontPage {
 
         const options: SingleFileOptions = {
             domain: `http${this.options.https ? 's' : ''}://${this.options.domain}`,
+            cdn_domain: this.options.cdn_domain,
             story: {
                 author: data.author,
                 cover: !!data.cover,

src/tools/index-processing.ts

@@ -16,6 +16,7 @@ import {escape, truncate} from 'lodash-es'
 import type {TruthyOption} from '../upstream/asyncglk/src/index-common.js'
 import {Uint8Array_to_base64} from '../common/file.js'
 import type {FileSize, ParchmentOptions} from '../common/interface.js'
+import {find_format} from '../common/formats.js'
 
 // Is ASCII really okay here?
 const utf8decoder = new TextDecoder('ascii', {fatal: true})
@@ -36,6 +37,7 @@ export interface Story {
 export interface SingleFileOptions {
     date?: TruthyOption
     domain?: string
+    cdn_domain?: string
     font?: TruthyOption
     gzip?: TruthyOption
     single_file?: TruthyOption
@@ -99,6 +101,14 @@ export async function process_index_html(options: SingleFileOptions, files: Map<
         }
         if (story.format) {
             parchment_options.story.format = story.format
+            const {engines} = find_format(story.format)
+            if (engines) {
+                parchment_options.engine_files = Object.fromEntries(await Promise.all(engines[0].load.map(async (path) => {
+                    const response = await fetch(`https://${options.cdn_domain}/dist/web/${path}`, {method: 'head'})
+                    const last_modified = response.headers.get('last-modified') ?? ''
+                    return [path, Math.floor(new Date(last_modified).getTime()/1000)]
+                })))
+            }
         }
     }