refactor platform

platform.ts

@@ -36,11 +36,48 @@ export function createPlatform(opts: {
 
   return {
     ...platform,
+
     async download(dir: string, book: Book): Promise<void> {
       await fs.mkdir(path.dirname(dir), { recursive: true });
       await fs.mkdir(dir);
-      await platform.download(dir, book);
+
+      const files: Array<() => Promise<string>> = await platform.getFiles(book);
+      const digits = String(files.length).length;
+
+      function pad(n: string) {
+        return n.padStart(digits, "0");
+      }
+
+      const supportedTypes = {
+        "image/png": "png",
+        "image/jpeg": "jpg",
+      };
+
+      for (const [n, dataUrl] of Object.entries(files)) {
+        const [prefix, base64] = (await dataUrl()).split(",", 2);
+        const [, type, encoding] =
+          /^data:([^;]*)(;base64)?$/.exec(prefix) ?? [];
+
+        const extension = supportedTypes[type];
+        if (!extension) {
+          throw new Error(
+            `It was ${type}. The image must be a file of type: ${[
+              ...Object.keys(supportedTypes),
+            ].join(", ")}.`,
+          );
+        }
+
+        if (encoding !== ";base64") {
+          throw new Error("Only base64 is supported.");
+        }
+
+        const buffer = Buffer.from(base64, "base64");
+        await fs.writeFile(`${dir}/${pad(n)}.${extension}`, buffer);
+      }
+
+      process.stderr.write(`\n`);
     },
+
     async logout() {
       await opts.db.run(
         `update platforms set secrets = 'null' where name = ?`,

platforms/dmm-books.ts

@@ -1,10 +1,16 @@
-import fs from "node:fs/promises";
 import type { Book } from "../library";
 import type { Browser, BrowserContext } from "../browser";
 
+type ImageFile = {
+  url: string;
+  blocks: Array<Record<string, number>>;
+  width: number;
+  height: number;
+};
+
 var NFBR: any;
 
-async function getFiles() {
+async function getImageFiles(): Promise<Array<ImageFile>> {
   const params = new URLSearchParams(location.search);
   const model = new NFBR.a6G.Model({
     settings: new NFBR.Settings("NFBR.SettingData"),
@@ -29,12 +35,7 @@ async function getFiles() {
   const a5n = new NFBR.a5n();
   await a5n.a5s(content, "configuration", a6l);
 
-  const files: Array<{
+  const imageFiles: Array<ImageFile> = [];
-    url: string;
-    blocks: [];
-    width: number;
-    height: number;
-  }> = [];
 
   for (const index of Object.keys(content.files)) {
     const file = content.files[index];
@@ -67,7 +68,7 @@ async function getFiles() {
 
     const url = `${a5w.url}${page.url}`;
 
-    files.push({
+    imageFiles.push({
       url,
       blocks,
       width: Width,
@@ -75,24 +76,19 @@ async function getFiles() {
     });
   }
 
-  return files;
+  return imageFiles;
 }
 
-async function drawImage(file: {
+async function drawImage(imageFile: ImageFile) {
-  url: string;
-  blocks: Array<Record<string, number>>;
-  width: number;
-  height: number;
-}) {
   const canvas = Object.assign(document.createElement("canvas"), {
-    width: file.width,
+    width: imageFile.width,
-    height: file.height,
+    height: imageFile.height,
   });
 
   const image = (await new Promise((resolve) => {
     Object.assign(new Image(), {
       crossOrigin: "use-credentials",
-      src: file.url,
+      src: imageFile.url,
       onload() {
         resolve(this);
       },
@@ -101,7 +97,7 @@ async function drawImage(file: {
 
   const ctx = canvas.getContext("2d")!;
 
-  for (const q of file.blocks) {
+  for (const q of imageFile.blocks) {
     ctx.drawImage(
       image,
       q.destX,
@@ -241,38 +237,21 @@ export function DmmBooks(browser: Browser) {
       process.stderr.write(`\n`);
     },
 
-    async download(dir: string, book: Book) {
+    async getFiles(book: Book): Promise<Array<() => Promise<string>>> {
       const ctx = await browser.loadBrowserContext("dmm-books");
       const page = await ctx.newPage();
 
       await page.goto(book.readerUrl);
 
-      const files = await page.evaluate(getFiles);
+      const imageFiles = await page.evaluate(getImageFiles);
-      const digits = String(files.length).length;
 
-      function pad(n: string) {
+      return imageFiles.map((imageFile) => async () => {
-        return n.padStart(digits, "0");
+        const dataUrl = await page.evaluate(drawImage, imageFile);
-      }
-
-      for (const [n, file] of Object.entries(files)) {
-        const dataUrl = await page.evaluate(drawImage, file);
-        const [prefix, base64] = dataUrl.split(",", 2);
-
-        if (!prefix.startsWith("data:image/png;")) {
-          throw new Error("Only image/png is supported.");
-        }
-
-        if (!prefix.endsWith(";base64")) {
-          throw new Error("Only base64 is supported.");
-        }
-
-        const buffer = Buffer.from(base64, "base64");
-        await fs.writeFile(`${dir}/${pad(n)}.png`, buffer);
 
         process.stderr.write(".");
-      }
 
-      process.stderr.write(`\n`);
+        return dataUrl;
+      });
     },
   };
 }

platforms/google-play-books.ts

@@ -1,8 +1,11 @@
-import fs from "node:fs/promises";
 import type { Book } from "../library";
 import type { Browser } from "../browser";
 
-async function getFiles(): Promise<Array<{ url: string }>> {
+type ImageFile = {
+  url: string;
+};
+
+async function getImageFiles(): Promise<Array<ImageFile>> {
   const pages: NodeListOf<HTMLElement> = await new Promise(async function (
     resolve,
     reject,
@@ -35,12 +38,11 @@ async function getFiles(): Promise<Array<{ url: string }>> {
     (el) => el.querySelector("svg image")!,
   );
 
-  const files = [...images].map((image) => ({ url: image.href.baseVal }));
+  return [...images].map((image) => ({ url: image.href.baseVal }));
-  return files;
 }
 
-async function drawImage(file: { url: string }): Promise<string> {
+async function fetchImage(imageFile: ImageFile): Promise<string> {
-  const res = await fetch(file.url);
+  const res = await fetch(imageFile.url);
   const blob = await res.blob();
   const dataUrl: string = await new Promise((resolve, reject) => {
     const fileReader = Object.assign(new FileReader(), {
@@ -98,7 +100,7 @@ export function GooglePlayBooks(browser: Browser) {
       process.stderr.write(`\n`);
     },
 
-    async download(dir: string, book: Book) {
+    async getFiles(book: Book): Promise<Array<() => Promise<string>>> {
       const ctx = await browser.loadBrowserContext("google-play-books");
       const page = await ctx.newPage();
 
@@ -140,43 +142,23 @@ export function GooglePlayBooks(browser: Browser) {
         });
       }
 
-      const fileMap: Map<string, { url: string; dataUrl: string }> = new Map();
+      const fileMap: Map<string, () => Promise<string>> = new Map();
 
       while (await next()) {
-        const files = await frame.evaluate(getFiles);
+        const imageFiles = await frame.evaluate(getImageFiles);
 
-        for (const file of files) {
+        for (const imageFile of imageFiles) {
-          if (fileMap.has(file.url)) continue;
+          if (fileMap.has(imageFile.url)) continue;
+
+          const dataUrl = await frame.evaluate(fetchImage, imageFile);
 
-          const dataUrl = await frame.evaluate(drawImage, file);
-          fileMap.set(file.url, { ...file, dataUrl });
           process.stderr.write(".");
+
+          fileMap.set(imageFile.url, async () => dataUrl);
         }
       }
 
-      const files = [...fileMap.values()];
+      return [...fileMap.values()];
-      const digits = String(files.length).length;
-
-      function pad(n: string) {
-        return n.padStart(digits, "0");
-      }
-
-      for (const [n, file] of Object.entries(files)) {
-        const [prefix, base64] = file.dataUrl.split(",", 2);
-
-        if (!prefix.startsWith("data:image/jpeg;")) {
-          throw new Error("Only image/jpeg is supported.");
-        }
-
-        if (!prefix.endsWith(";base64")) {
-          throw new Error("Only base64 is supported.");
-        }
-
-        const buffer = Buffer.from(base64, "base64");
-        await fs.writeFile(`${dir}/${pad(n)}.jpeg`, buffer);
-      }
-
-      process.stderr.write(`\n`);
     },
   };
 }