import { PDFDocument, ParseSpeeds } from 'pdf-lib';


export type Metadata = {
    deleteAll?: boolean,        // Delete all metadata if set to true
    author?: string,            // The author of the document
    creationDate?: Date,        // The creation date of the document (format: yyyy/MM/dd HH:mm:ss)
    creator?: string,           // The creator of the document
    keywords?: string,          // The keywords for the document
    modificationDate?: Date,    // The modification date of the document (format: yyyy/MM/dd HH:mm:ss)
    producer?: string,          // The producer of the document
    subject?: string,           // The subject of the document
    title?: string,             // The title of the document
    //trapped?: string,           // The trapped status of the document
    //allRequestParams?: object,  // Map list of key and value of custom parameters. Note these must start with customKey and customValue if they are non-standard
}

/**
 * 
 * @param {Uint16Array} snapshot
 * @param {Metadata} metadata - Set property to null or "" to clear, undefined properties will be skipped.
 * @returns Promise<Uint8Array>
 */
export async function updateMetadata(snapshot: string | Uint8Array | ArrayBuffer, metadata: Metadata): Promise<Uint8Array> {
    // Load the original PDF file
    const pdfDoc = await PDFDocument.load(snapshot, {
        parseSpeed: ParseSpeeds.Slow,
        updateMetadata: false,
    });

    if (!metadata || metadata.deleteAll) {
        pdfDoc.setAuthor("");
        pdfDoc.setCreationDate(new Date(0))
        pdfDoc.setCreator("")
        pdfDoc.setKeywords([])
        pdfDoc.setModificationDate(new Date(0))
        pdfDoc.setProducer("")
        pdfDoc.setSubject("")
        pdfDoc.setTitle("")
    }
    if (!metadata) {
        return pdfDoc.save();
    }

    if(metadata.author)
        pdfDoc.setAuthor(metadata.author);
    if(metadata.creationDate)
        pdfDoc.setCreationDate(metadata.creationDate)
    if(metadata.creator)
        pdfDoc.setCreator(metadata.creator)
    if(metadata.keywords)
        pdfDoc.setKeywords(metadata.keywords.split(","))
    if(metadata.modificationDate)
        pdfDoc.setModificationDate(metadata.modificationDate)
    if(metadata.producer)
        pdfDoc.setProducer(metadata.producer)
    if(metadata.subject)
        pdfDoc.setSubject(metadata.subject)
    if(metadata.title)
        pdfDoc.setTitle(metadata.title)

    // TODO add trapped and custom metadata. May need another library

    // Serialize the modified document
    return pdfDoc.save();
};