import Queue from './Queue.js'

class Pool<T> {
    /* *
     * this class handle the socket connectd
     * queue of sockets and manages connection with the workers
     * */

    private enabled: Queue<string>;
    private disabled: string[];
    private items: { [key: string]: T };

    constructor() {
        this.enabled = new Queue();
        this.disabled = [];
        this.items = {}
    }

    has( id: string ): boolean {
        return this.items[id] ? true : false;
    }

    add( id: string, item: T ): boolean {
        // if the item is already in the pool
        if (this.has(id)) this.remove(id);
        // add to the queue
        this.enabled.enqueue(id);
        // add the item to the pool
        this.items[id] = item;
        // return true
        return false;
    }

    disable(id: string): boolean {
        if( !this.has(id) ) return false;
        // if it is in the disable list, job done
        if( this.disabled.indexOf(id) !== -1 ) return true;
        // if it is in the enabled list, remove it
        if( this.enabled.indexOf(id) !== -1 ){
            this.enabled.remove(id);
            // add the slave to the disable list
            this.disabled.push(id);
            return true;
        }
        return false;
    }

    disableUntil(id: string, timeOrCondition: number | Function): undefined {
        // if it is not in the pool, return false
        if( !this.has(id) ) return;
        // check if timeOrCondition is a number or a function
        let time = null;
        let condition : any = null;
        if(typeof timeOrCondition === 'number')
            time = timeOrCondition;
        else if(typeof timeOrCondition === 'function')
            condition = timeOrCondition;
        else throw new Error('timeOrCondition must be a number or a function');
        // if it is already disabled, we want to keep it disabled until the timeOrCondition is met
        // if it is in the enabled list, disable it
        if( this.enabled.indexOf(id) !== -1 ) this.disable(id);
        // check that the id is in the disabled list
        if( this.disabled.indexOf(id) === -1 ) throw new Error('id is not in the disabled list');
        // if time is defined, set a timeout
        if(time) setTimeout(() => this.enable(id), time);
        // if condition is defined, set a interval
        if(condition){
            let interval = setInterval(() => {
                if(condition()){
                    clearInterval(interval);
                    this.enable(id);
                }
            }, 100);
        }
    }


    enable(id: string) : boolean {
        // if it is not in the pool, return false
        if( !this.has(id) ) return false;
        // if it is already enabled, job done
        if( this.enabled.indexOf(id) !== -1 ) return true;
        // if it is in the disabled list, remove it
        if( this.disabled.indexOf(id) !== -1 ){
            // remove the slave from the disable list
            this.disabled = this.disabled.filter( e => e !== id );
            // add the slave to the queue
            this.enabled.enqueue(id);
            return true
        }
        return false;
    }

    nextAndEnable() : string | boolean {
        // if the diabled list is empty, return false
        if( this.disabled.length === 0 ) return false;
        // get the first element of the disabled list
        let id = this.disabled[0];
        // and enable it
        this.enable(id);
        // return the id
        return id;
    }

    rotate() : T | null { 
        // dequeue and enqueue
        if(this.size() === 0) return null
        const id = this.enabled.dequeue()
        if(!id) return null
        this.enabled.enqueue(id)
        return this.items[id]
    }

    hasEnabled() : boolean {
        return this.enabled.size() > 0;
    }


    nextAndDisable() : T | null { // dequeue and disable
        if(this.size() === 0) return null
        const id = this.enabled.dequeue();
        if(!id) return null;
        this.disabled.push(id);
        return this.items[id];
    }

    // remove value while maintaining order
    remove( id: string ) : T | null {
        // look in the queue for the id
        let result = this._lookUp(id);
        if(result){
            let index = result.index;
            let list = result.list;
            // remove the lists
            if(list === 'enabled')
                this.enabled.removeAt(index);
            else
                this.disabled.splice(index, 1);
            // remove the items
            let item = this.items[id];
            delete this.items[id];
            // return true
            return item;
        }
        return null;
    }

    removeOne() : T | null {
        // get the first element of the enabled list
        if(this.enabled.size() > 0){
            let id = this.enabled.dequeue();
            if(id === undefined || id === false) return null;
            // remove the item from the pool
            let item = this.items[id];
            delete this.items[id];
            return item;
        }
        return null;
    }

    get( id: string ) : T | null {
        /* get the item from the pool */
        if(!this.has(id)) return null;
        return this.items[id];
    }

    // get the size of the pool
    size() : number {
        return Object.keys(this.items).length;
    }

    // lenght of the pool
    length() : number {
        return this.size();
    }

    // count the enabled elements
    getEnabledCount() : number {
        return this.enabled.size();
    }

    // count the disabled elements
    getDisabledCount() : number {
        return this.disabled.length;
    }

    // check if queue is empty
    isEmpty() : boolean {
        return this.size() === 0;
    }

    _lookUp( id : string ) : { index: number, list: string } | false {
        // look in the queue for the id
        let index = this.enabled.indexOf(id);
        if(!(index === -1))
            return { index, list: 'enabled' };
        // look in the disable list for the id
        index = this.disabled.indexOf(id);
        if(!(index === -1))
            return { index, list: 'disabled' };
        return false;
    }

    toArray() : T[] {
        return Object.values(this.items);
    }

    print() : void {
        console.log(this.toArray());
    }

    getEnabled() : string[] {
        return this.enabled.toArray();
    }

    getEnabledObjects() : T[] {
        return this.enabled.toArray().map( id => this.items[id] );
    }

    getDisabled() : string[] {
        return this.disabled;
    }

    getDisabledObjects() : T[] {
        return this.disabled.map( id => this.items[id] );
    }

    getConnections() : string[] {
        return Object.keys(this.items);
    }

    healthCheck() : boolean {
        let total = this.size();
        let enabled = this.getEnabled().length;
        let disabled = this.getDisabled().length;
        if(total === (enabled + disabled))
            return true;
        else return false;
    }

    // synonims
    next = this.rotate
    pop = this.nextAndDisable;
    shift = this.nextAndEnable;
    unshift = this.add;
    push = this.add;
    count = this.size;
    removeAt = this.remove;
    removeItem = this.remove;


}

export default Pool;