import { Coder, Reader, Writer } from './index';

export class TupleCoder extends Coder {
    readonly coders: Array<Coder>;

    constructor(coders: Array<Coder>, localName: string) {
        let dynamic = false;
        const types: Array<string> = [];
        coders.forEach(coder => {
            if (coder.dynamic) {
                dynamic = true;
            }
            types.push(coder.type);
        });
        const type = (`tuple(${ types.join(',') })`);

        super('tuple', type, localName, dynamic);
        this.coders = coders;
    }

    defaultValue(): any {
        let values: any = [ ];
        this.coders.forEach(coder => {
            values.push(coder.defaultValue());
        });

        // We only output named properties for uniquely named coders
        const uniqueNames = this.coders.reduce((accum, coder) => {
            const name = coder.localName;
            if (name) {
                if (!accum[name]) {
                    accum[name] = 0;
                }
                accum[name]++;
            }
            return accum;
        }, { });

        // Add named values
        const tuple = {};
        this.coders.forEach((coder: Coder, index: number) => {
            let name = coder.localName;
            if (!name || uniqueNames[name] !== 1) {
                return;
            }

            if (name === 'length') {
                name = '_length';
            }

            if (values[name] != null) {
                return;
            }

            if (this.localName !== '_') {
                tuple[name] = values[index];
            }
            // values[name] = values[index];
        });

        if (Object.keys(tuple).length === values.length) {
            values = tuple;
        }

        return Object.freeze(values);
    }

    encode(writer: Writer, value: Array<any> | { [ name: string ]: any }): number {
        return this.pack(writer, this.coders, value);
    }

    decode(reader: Reader): any {
        return reader.coerce(this, this.unpack(reader, this.coders));
    }
}