import MysqlConnectionManager, {query} from "./MysqlConnectionManager";
import Validator from "./Validator";
import {Connection} from "mysql";
import ModelQuery, {ModelQueryResult} from "./ModelQuery";
import {Request} from "express";
import {Type} from "../Utils";

export interface ModelClass<M extends Model> extends Type<M> {
    getFactory<M extends Model>(factory?: ModelFactory<M>): ModelFactory<M>;

    table: string;

    getPrimaryKey(modelData: any): string;

    getPrimaryKeyFields(): string[];

    select<M extends Model>(...fields: string[]): ModelQuery<M>;

    update<M extends Model>(data: { [key: string]: any }): ModelQuery<M>;

    delete<M extends Model>(): ModelQuery<M>;
}

export default abstract class Model {
    public static get table(): string {
        return this.name
                .replace(/(?:^|\.?)([A-Z])/g, (x, y) => '_' + y.toLowerCase())
                .replace(/^_/, '')
            + 's';
    }

    public static async getById<T extends Model>(this: ModelClass<T>, id: number): Promise<T | null> {
        return this.select<T>().where('id', id).first();
    }

    public static async paginate<T extends Model>(this: ModelClass<T>, request: Request, perPage: number = 20, query?: ModelQuery<T>): Promise<ModelQueryResult<T>> {
        let page = request.params.page ? parseInt(request.params.page) : 1;
        if (!query) query = this.select();
        if (request.params.sortBy) {
            const dir = request.params.sortDirection;
            query = query.sortBy(request.params.sortBy, dir === 'ASC' || dir === 'DESC' ? dir : undefined);
        } else {
            query = query.sortBy('id');
        }
        return await query.paginate(page, perPage);
    }

    public static select<T extends Model>(this: ModelClass<T>, ...fields: string[]): ModelQuery<T> {
        return ModelQuery.select(this, ...fields);
    }

    public static update<T extends Model>(this: ModelClass<T>, data: { [key: string]: any }): ModelQuery<T> {
        return ModelQuery.update(this, data);
    }

    public static delete<T extends Model>(this: ModelClass<T>): ModelQuery<T> {
        return ModelQuery.delete(this);
    }

    public static getPrimaryKey(modelData: any): string {
        return this.getPrimaryKeyFields().map(f => `${modelData[f]}`).join(',');
    }

    public static getPrimaryKeyFields(): string[] {
        return ['id'];
    }

    public static async loadRelation<T extends Model>(models: T[], relation: string, model: Function, localField: string) {
        const loadMap: { [p: number]: (model: T) => void } = {};
        const ids = models.map(m => {
            m.relations[relation] = null;
            if (m[localField]) loadMap[m[localField]] = v => m.relations[relation] = v;
            return m[localField];
        }).filter(id => id);
        for (const v of await (<any>model).models((<any>model).select().whereIn('id', ids))) {
            loadMap[v.id!](v);
        }
    }

    public static getFactory<T extends Model>(this: ModelClass<T>, factory?: ModelFactory<T>): ModelFactory<T> {
        if (factory === undefined) {
            factory = (<any>this).FACTORY;
            if (factory === undefined) factory = data => new (<any>this)(data);
        }
        return factory;
    }


    protected readonly modelClass: ModelClass<this> = <ModelClass<this>>this.constructor;
    protected readonly properties: ModelProperty<any>[] = [];
    public id?: number;
    private readonly automaticIdProperty: boolean;

    [key: string]: any;

    public constructor(data: any, automaticIdProperty: boolean = true) {
        this.automaticIdProperty = automaticIdProperty;
        if (automaticIdProperty) {
            this.addProperty<number>('id', new Validator());
        }
        this.init();
        this.updateWithData(data);
    }

    public getPrimaryKey(): string {
        return this.modelClass.getPrimaryKey(this);
    }

    public getPrimaryKeyFields(): string[] {
        return this.modelClass.getPrimaryKeyFields();
    }

    protected abstract init(): void;

    protected addProperty<T>(name: string, validator?: Validator<T> | RegExp) {
        if (validator === undefined) validator = new Validator();
        if (validator instanceof RegExp) {
            const regexp = validator;
            validator = new Validator().regexp(regexp);
        }

        const prop = new ModelProperty<T>(name, validator);
        this.properties.push(prop);
        Object.defineProperty(this, name, {
            get: () => prop.value,
            set: (value: T) => prop.value = value,
        });
    }

    private updateWithData(data: any) {
        if (this.automaticIdProperty) this.id = data['id'];

        for (const prop of this.properties) {
            if (data[prop.name] !== undefined) {
                this[prop.name] = data[prop.name];
            }
        }
    }

    protected async beforeSave(exists: boolean, connection: Connection): Promise<void> {
    }

    protected async afterSave(): Promise<void> {
    }

    public async save(connection?: Connection, postHook?: (callback: () => Promise<void>) => void): Promise<void> {
        await this.validate(false, connection);

        const exists = await this.exists();
        let needs_full_update = false;

        if (connection) {
            needs_full_update = await this.saveTransaction(connection, exists, needs_full_update);
        } else {
            needs_full_update = await MysqlConnectionManager.wrapTransaction(async connection => this.saveTransaction(connection, exists, needs_full_update));
        }

        const callback = async () => {
            if (needs_full_update) {
                this.updateWithData((await this.modelClass.select().where('id', this.id!).limit(1).execute()).results[0]);
            }

            await this.afterSave();
        };

        if (connection) {
            postHook!(callback);
        } else {
            await callback();
        }
    }

    private async saveTransaction(connection: Connection, exists: boolean, needs_full_update: boolean): Promise<boolean> {
        // Before save
        await this.beforeSave(exists, connection);
        if (exists && this.hasOwnProperty('updated_at')) {
            this.updated_at = new Date();
        }

        const props = [];
        const values = [];

        if (exists) {
            const data: any = {};
            for (const prop of this.properties) {
                if (prop.value !== undefined) {
                    data[prop.name] = prop.value;
                } else {
                    needs_full_update = true;
                }
            }
            let query = this.modelClass.update(data);
            for (const indexField of this.getPrimaryKeyFields()) {
                query = query.where(indexField, this[indexField]);
            }
            await query.execute(connection);
        } else {
            const props_holders = [];
            for (const prop of this.properties) {
                if (prop.value !== undefined) {
                    props.push(prop.name);
                    props_holders.push('?');
                    values.push(prop.value);
                } else {
                    needs_full_update = true;
                }
            }
            const result = await query(`INSERT INTO ${this.table} (${props.join(', ')}) VALUES(${props_holders.join(', ')})`, values, connection);

            if (this.automaticIdProperty) this.id = result.other.insertId;
        }

        return needs_full_update;
    }

    public get table(): string {
        return this.modelClass.table;
    }

    public async exists(): Promise<boolean> {
        if (!this.id) return false;

        let query = this.modelClass.select('1');
        for (const indexField of this.getPrimaryKeyFields()) {
            query = query.where(indexField, this[indexField]);
        }
        return typeof (await query.first()) !== 'undefined';
    }

    public async delete(): Promise<void> {
        if (!(await this.exists())) throw new Error('This model instance doesn\'t exist in DB.');

        let query = this.modelClass.delete();
        for (const indexField of this.getPrimaryKeyFields()) {
            query = query.where(indexField, this[indexField]);
        }
        await query.execute();
        if (this.automaticIdProperty) this.id = undefined;
    }

    public async validate(onlyFormat: boolean = false, connection?: Connection): Promise<void[]> {
        return await Promise.all(this.properties.map(prop => prop.validate(onlyFormat, connection)));
    }
}

export interface ModelFactory<T extends Model> {
    (data: any): T;
}

class ModelProperty<T> {
    public readonly name: string;
    private readonly validator: Validator<T>;
    private val?: T;

    constructor(name: string, validator: Validator<T>) {
        this.name = name;
        this.validator = validator;
    }

    public async validate(onlyFormat: boolean, connection?: Connection): Promise<void> {
        return await this.validator.execute(this.name, this.value, onlyFormat, connection);
    }

    public get value(): T | undefined {
        return this.val;
    }

    public set value(val: T | undefined) {
        this.val = val;
    }
}

export const EMAIL_REGEX = /^[a-zA-Z0-9.!#$%&'*+\\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)+$/;