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🧹 [code health improvement] Refactor inspectPowerPointPackage into modular helper functions #61

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Merged
MarsLuay merged 1 commit into from
Aug 25, 2026
Merged

🧹 [code health improvement] Refactor inspectPowerPointPackage into modular helper functions #61

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56 changes: 49 additions & 7 deletions src/PowerPointPackage.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -87,13 +87,20 @@ const MUTABLE_PART_PATTERNS = [
/^ppt\/slides\/_rels\/slide\d+\.xml\.rels$/
];

export function inspectPowerPointPackage(buffer: ArrayBuffer): PowerPointPackageInspection {
const bytes = new Uint8Array(buffer);
if (bytes.byteLength < EOCD_MIN_LENGTH) {
throw new Error('The exported file is too small to be an Open XML ZIP package.');
}
interface CentralDirectoryHeader {
totalEntries: number;
centralDirectorySize: number;
centralDirectoryOffset: number;
}

const view = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
interface ParsedZipEntries {
entries: PowerPointPackageEntry[];
entryMap: Map<string, PowerPointPackageEntry>;
duplicateEntries: string[];
unsafePaths: string[];
}

function readZipCentralDirectoryHeader(view: DataView, byteLength: number): CentralDirectoryHeader {
const eocdOffset = findEndOfCentralDirectory(view);
if (eocdOffset === -1) {
throw new Error('The file is not a valid Open XML ZIP package.');
Expand All @@ -118,10 +125,23 @@ export function inspectPowerPointPackage(buffer: ArrayBuffer): PowerPointPackage
throw new Error('ZIP64 PowerPoint packages need explicit validation before saving.');
}

if (centralDirectoryOffset + centralDirectorySize > bytes.byteLength) {
if (centralDirectoryOffset + centralDirectorySize > byteLength) {
throw new Error('The ZIP central directory points outside the file.');
}

return {
totalEntries,
centralDirectorySize,
centralDirectoryOffset,
};
}

function parseZipCentralDirectoryEntries(
bytes: Uint8Array,
view: DataView,
header: CentralDirectoryHeader,
): ParsedZipEntries {
const { totalEntries, centralDirectorySize, centralDirectoryOffset } = header;
const entries: PowerPointPackageEntry[] = [];
const entryMap = new Map<string, PowerPointPackageEntry>();
const duplicateEntries: string[] = [];
Expand Down Expand Up @@ -181,6 +201,28 @@ export function inspectPowerPointPackage(buffer: ArrayBuffer): PowerPointPackage
throw new Error('The ZIP central directory entry count does not match its declared size.');
}

return {
entries,
entryMap,
duplicateEntries,
unsafePaths,
};
}

export function inspectPowerPointPackage(buffer: ArrayBuffer): PowerPointPackageInspection {
const bytes = new Uint8Array(buffer);
if (bytes.byteLength < EOCD_MIN_LENGTH) {
throw new Error('The exported file is too small to be an Open XML ZIP package.');
}

const view = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
const header = readZipCentralDirectoryHeader(view, bytes.byteLength);
const { entries, entryMap, duplicateEntries, unsafePaths } = parseZipCentralDirectoryEntries(
bytes,
view,
header,
);

const slidePaths = entries
.map((entry) => entry.name)
.filter((name) => /^ppt\/slides\/slide\d+\.xml$/.test(name))
Expand Down