import { AbortError, } from './Errors.js';
import { Deferred } from './Deferred.js';
import { AbstractStreamReader } from "./AbstractStreamReader.js";
/**
 * Node.js Readable Stream Reader
 * Ref: https://nodejs.org/api/stream.html#readable-streams
 */
export class StreamReader extends AbstractStreamReader {
    constructor(s) {
        super();
        this.s = s;
        /**
         * Deferred used for postponed read request (as not data is yet available to read)
         */
        this.deferred = null;
        if (!s.read || !s.once) {
            throw new Error('Expected an instance of stream.Readable');
        }
        this.s.once('end', () => {
            this.endOfStream = true;
            if (this.deferred) {
                this.deferred.resolve(0);
            }
        });
        this.s.once('error', err => this.reject(err));
        this.s.once('close', () => this.abort());
    }
    /**
     * Read chunk from stream
     * @param buffer Target Uint8Array (or Buffer) to store data read from stream in
     * @param mayBeLess - If true, may fill the buffer partially
     * @returns Number of bytes read
     */
    async readFromStream(buffer, mayBeLess) {
        if (buffer.length === 0)
            return 0;
        const readBuffer = this.s.read(buffer.length);
        if (readBuffer) {
            buffer.set(readBuffer);
            return readBuffer.length;
        }
        const request = {
            buffer,
            mayBeLess,
            deferred: new Deferred()
        };
        this.deferred = request.deferred;
        this.s.once('readable', () => {
            this.readDeferred(request);
        });
        return request.deferred.promise;
    }
    /**
     * Process deferred read request
     * @param request Deferred read request
     */
    readDeferred(request) {
        const readBuffer = this.s.read(request.buffer.length);
        if (readBuffer) {
            request.buffer.set(readBuffer);
            request.deferred.resolve(readBuffer.length);
            this.deferred = null;
        }
        else {
            this.s.once('readable', () => {
                this.readDeferred(request);
            });
        }
    }
    reject(err) {
        this.interrupted = true;
        if (this.deferred) {
            this.deferred.reject(err);
            this.deferred = null;
        }
    }
    async abort() {
        this.reject(new AbortError());
    }
    async close() {
        return this.abort();
    }
}