import { PropSchema, serialize, deserialize, custom, setDefaultModelSchema, getDefaultModelSchema } from 'serializr';
// import { Field } from '../../fields/Doc';

let serializing = 0;
export function afterDocDeserialize(cb: (err: any, val: any) => void, err: any, newValue: any) {
    serializing++;
    cb(err, newValue);
    serializing--;
}

const serializationTypes: { [name: string]: { ctor: { new (): any }; afterDeserialize?: (obj: any) => void | Promise<any> } } = {};
const reverseMap: { [ctor: string]: string } = {};

export namespace SerializationHelper {
    export function IsSerializing() {
        return serializing > 0;
    }

    export function Serialize(obj: any /* Field */): any {
        if (obj === undefined || obj === null) {
            return null;
        }

        if (typeof obj !== 'object') {
            return obj;
        }

        serializing++;
        if (!(obj.constructor.name in reverseMap)) {
            serializing--;
            throw Error(`Error: type '${obj.constructor.name}' not registered. Make sure you register it using a @Deserializable decorator`);
        }

        const json = serialize(obj);
        json.__type = reverseMap[obj.constructor.name];
        serializing--;
        return json;
    }

    export async function Deserialize(obj: any): Promise<any> {
        if (obj === undefined || obj === null) {
            return undefined;
        }

        if (typeof obj !== 'object') {
            return obj;
        }

        if (!obj.__type) {
            console.warn("No property 'type' found in JSON.");
            return undefined;
        }

        if (!(obj.__type in serializationTypes)) {
            throw Error(`type '${obj.__type}' not registered. Make sure you register it using a @Deserializable decorator`);
        }

        const type = serializationTypes[obj.__type];
        const value = await new Promise(res => {
            deserialize(type.ctor, obj, (err, result) => res(result));
        });
        type.afterDeserialize?.(value);

        return value;
    }
}

export function Deserializable(classNameForSerializer: string, afterDeserialize?: (obj: any) => void | Promise<any>, constructorArgs?: [string]): (constructor: { new (...args: any[]): any }) => void {
    function addToMap(className: string, Ctor: { new (...args: any[]): any }) {
        const schema = getDefaultModelSchema(Ctor) as any;
        if (schema.targetClass !== Ctor || constructorArgs) {
            setDefaultModelSchema(Ctor, { ...schema, factory: (context: any) => new Ctor(...(constructorArgs ?? []).map(arg => context.json[arg])) });
        }
        if (!(className in serializationTypes)) {
            serializationTypes[className] = { ctor: Ctor, afterDeserialize };
            reverseMap[Ctor.name] = className;
        } else {
            throw new Error(`Name ${className} has already been registered as deserializable`);
        }
    }
    return (ctor: { new (...args: any[]): any }) => addToMap(classNameForSerializer, ctor);
}

export function autoObject(): PropSchema {
    return custom(
        s => SerializationHelper.Serialize(s),
        (json: any, context: any, oldValue: any, cb: (err: any, result: any) => void) => SerializationHelper.Deserialize(json).then(res => cb(null, res))
    );
}