import {Injectable} from 'angular2/core';
import {Http, Headers} from 'angular2/http';

import 'rxjs/Rx'; // import all RxJS operators

import {QueryMode} from './query-mode';
import {QueryState} from './query-state';
import {QueryStep} from './query-step';

@Injectable()
export class QueryService {
        
    public queryState: QueryState;
    
    public ismiObjectTypes;
    
    public QUERY_MODES: QueryMode[] = [
        {id: 'type_is', label:'Object type is'},
        {id: 'att_contains', label: 'Attribute contains'}];
        
    constructor(private _http: Http) {
        this.queryState = {
            'steps': [],
            'cypherQuery': '',
            'cyperParams': {}, 
            'results': [], 
            numResults: 0};
    }
    
    getQueryModes(): QueryMode[] {
        return this.QUERY_MODES;
    }
    
    getQueryOptions(queryMode: QueryMode) {
        var options = ['a1', 'b1', 'c1'];
        if (queryMode.id === 'att_contains') {
            options = ['d', 'e', 'f'];
        } else if (queryMode.id === 'type_is') {
            options = this.ismiObjectTypes;
        }
        console.debug("getQueryOptions returns: ", options);
        return options;
    }
    
    setupIsmiObjectTypes() {
        var query = `MATCH (n) WITH DISTINCT labels(n) AS labels
                UNWIND labels AS label 
                RETURN DISTINCT label ORDER BY label`;

        var res = this.fetchCypherResult(query);
        res.subscribe(
            data => {
                console.debug("neo4j data=", data);
                this.ismiObjectTypes = data.data.map(elem => elem[0]).filter(elem => elem[0] != "_");
                console.debug("ismi types=", this.ismiObjectTypes);
                },
            err => console.error("neo4j error=", err),
            () => console.debug('neo4j query Complete')
        );
    }
    
    setQueryStep(index: number, step: QueryStep) {
        this.queryState.steps[index] = step;
        this.createCypherQuery();
    }
    
    createCypherQuery() {
        var cypher = '';
        var step = this.queryState.steps[0];
        if (step.mode.id === 'type_is') {
            cypher = `MATCH (e:${step.objectType}) return e`;
        }
        
        this.queryState.cypherQuery = cypher;
    }
    
    fetchCypherResult(query: string, params = {}) {
        var headers = new Headers();
        headers.append('Authorization', 'Basic ' + btoa('neo4j' + ':' + 'neo5j'));
        headers.append('Content-Type', 'application/json');
        headers.append('Accept', 'application/json');
        // put headers in options
        var opts = {'headers': headers};
        // create POST data from query
        var data = JSON.stringify({'query': query, 'params': params});
        // make post request asynchronously
        var resp = this._http.post('http://localhost:7474/db/data/cypher/', data, opts)
        // filter result as JSON
        .map(res => res.json());
        // return Observable
        return resp;
    }
}