feat: open multi-part packages in browser

src/source-file.ts

@@ -1,6 +1,33 @@
 import type { SourceKind } from './worker/onenote.client.js';
 
 export const MAX_SOURCE_FILE_BYTES = 512 * 1024 * 1024;
+export const MAX_SOURCE_PARTS = 256;
+
+export interface SourceFileDescriptor {
+  name: string;
+  size: number;
+}
+
+interface SourceFileSelectionFailure {
+  ok: false;
+  title: string;
+  message: string;
+}
+
+export type SourceFileSelection<T extends SourceFileDescriptor> =
+  | {
+      ok: true;
+      kind: 'one';
+      source: T;
+      cabinetParts: [];
+    }
+  | {
+      ok: true;
+      kind: 'onepkg';
+      source: T;
+      cabinetParts: T[];
+    }
+  | SourceFileSelectionFailure;
 
 export function sourceKindFromFileName(fileName: string): SourceKind | null {
   const normalized = fileName.toLocaleLowerCase('en-US');
@@ -8,3 +35,101 @@ export function sourceKindFromFileName(fileName: string): SourceKind | null {
   if (normalized.endsWith('.one')) return 'one';
   return null;
 }
+
+export function isCabinetPartFileName(fileName: string): boolean {
+  return fileName.toLocaleLowerCase('en-US').endsWith('.cab');
+}
+
+export function selectSourceFiles<T extends SourceFileDescriptor>(
+  files: readonly T[]
+): SourceFileSelection<T> {
+  if (files.length === 0) {
+    return invalidSelection();
+  }
+  if (files.length > MAX_SOURCE_PARTS) {
+    return {
+      ok: false,
+      title: 'Too many package parts',
+      message: `Choose at most ${MAX_SOURCE_PARTS} files for one cabinet set.`,
+    };
+  }
+
+  const sections: T[] = [];
+  const packages: T[] = [];
+  const cabinetParts: T[] = [];
+  for (const file of files) {
+    const kind = sourceKindFromFileName(file.name);
+    if (kind === 'one') sections.push(file);
+    else if (kind === 'onepkg') packages.push(file);
+    else if (isCabinetPartFileName(file.name)) cabinetParts.push(file);
+    else {
+      return {
+        ok: false,
+        title: 'Unsupported file name',
+        message:
+          'Choose one .one file, or one .onepkg file together with its .cab parts.',
+      };
+    }
+  }
+
+  const validSection =
+    sections.length === 1 && packages.length === 0 && cabinetParts.length === 0;
+  const validPackage = sections.length === 0 && packages.length === 1;
+  if (!validSection && !validPackage) return invalidSelection();
+
+  const seenNames = new Set<string>();
+  let totalSize = 0;
+  for (const file of files) {
+    const nameKey = file.name.normalize('NFC').toLocaleLowerCase('en-US');
+    if (seenNames.has(nameKey)) {
+      return {
+        ok: false,
+        title: 'Duplicate file name',
+        message: `The selection contains more than one file named ${file.name}.`,
+      };
+    }
+    seenNames.add(nameKey);
+    if (!Number.isSafeInteger(file.size) || file.size < 0) {
+      return {
+        ok: false,
+        title: 'Invalid file size',
+        message: `The browser reported an invalid size for ${file.name}.`,
+      };
+    }
+    if (file.size > MAX_SOURCE_FILE_BYTES) {
+      return {
+        ok: false,
+        title: 'File is too large',
+        message: `${file.name} exceeds the current 512 MiB safety limit.`,
+      };
+    }
+    totalSize += file.size;
+    if (!Number.isSafeInteger(totalSize) || totalSize > MAX_SOURCE_FILE_BYTES) {
+      return {
+        ok: false,
+        title: 'Package set is too large',
+        message:
+          'The selected .onepkg and .cab files exceed the combined 512 MiB safety limit.',
+      };
+    }
+  }
+
+  if (validSection) {
+    return { ok: true, kind: 'one', source: sections[0]!, cabinetParts: [] };
+  }
+  return {
+    ok: true,
+    kind: 'onepkg',
+    source: packages[0]!,
+    cabinetParts,
+  };
+}
+
+function invalidSelection(): SourceFileSelectionFailure {
+  return {
+    ok: false,
+    title: 'Choose one OneNote source',
+    message:
+      'Choose one .one file, or one .onepkg file together with its .cab parts.',
+  };
+}