Add the database sizes into the sidebar (closes #21)

module/apps/ArtSidebar.mjs

@@ -1,8 +1,10 @@
 import { api } from "../api.mjs";
 import { __ID__, filePath } from "../consts.mjs";
+import { getFileSize } from "../utils/fs.mjs";
 
 const { HandlebarsApplicationMixin } = foundry.applications.api;
 const { AbstractSidebarTab } = foundry.applications.sidebar;
+const { deepClone } = foundry.utils;
 
 export class ArtSidebar extends HandlebarsApplicationMixin(AbstractSidebarTab) {
 	// #region Options
@@ -30,16 +32,32 @@ export class ArtSidebar extends HandlebarsApplicationMixin(AbstractSidebarTab) {
 	// #endregion Options
 
 	// #region Data Prep
-	_preparePartContext(partID, ctx) {
+	async _preparePartContext(partID, ctx) {
+		ctx = deepClone(ctx);
+
 		switch (partID) {
+			case `tokens`: {
+				await this._prepareTokensContext(ctx);
+				break;
+			};
+			case `artists`: {
+				await this._prepareArtistsContext(ctx);
+				break;
+			};
 		};
 
 		return ctx;
 	};
 
-	_prepareTokensContext(ctx) {};
+	async _prepareTokensContext(ctx) {
+		const size = await getFileSize(filePath(`storage/db/images.json`));
+		ctx.size = size.friendly;
+	};
 
-	_prepareArtistsContext(ctx) {};
+	async _prepareArtistsContext(ctx) {
+		const size = await getFileSize(filePath(`storage/db/artists.json`));
+		ctx.size = size.friendly;
+	};
 	// #endregion Data Prep
 
 	// #region Actions

module/utils/fs.mjs

@@ -37,6 +37,30 @@ export async function lastModifiedAt(path) {
 	};
 };
 
+export async function getFileSize(path) {
+	try {
+		const response = await fetch(filePath(path), { method: `HEAD` });
+		const bytes = response.headers.get(`Content-Length`);
+		if (!bytes) { return null }
+
+		// round the non-bytes to 2 decimal places
+		const kilobytes = Math.floor(bytes / 10) / 100;
+		const megabytes = Math.floor(bytes / 10_000) / 100;
+
+		// determine the most appropriate unit to use
+		let friendly = `${bytes} bytes`;
+		if (megabytes > 0.25) {
+			friendly = `${megabytes}MB`;
+		} else if (kilobytes > 0) {
+			friendly = `${kilobytes}KB`;
+		};
+
+		return { bytes, kilobytes, megabytes, friendly };
+	} catch {
+		return null;
+	};
+};
+
 export async function getFile(path) {
 	try {
 		return fetchJsonWithTimeout(filePath(path));