'use strict';

var express = require('express');
var morgan = require('morgan');
var bodyParser = require('body-parser');
var app = express();
var curlify = require('request-as-curl');
var rp = require('request-promise-native');

var timeout = process.env.TIMEOUT;

var hosts = [];

app.use(morgan('combined'));
app.use(bodyParser.json());

function setCORSHeaders(res) {
    res.setHeader("Access-Control-Allow-Origin", "*");
    res.setHeader("Access-Control-Allow-Methods", "POST");
    res.setHeader("Access-Control-Allow-Headers", "accept, content-type");
}

app.all('/', function(req, res) {
    setCORSHeaders(res);
    console.log(curlify(req, req.body));
    res.send('https://grafana.com/plugins/grafana-simple-json-datasource\n');
    res.end();
});

var search_result = [];
/*
app.all('/search', function(req, res) {
    console.log(curlify(req, req.body));
    search_result = [];

    var results = hosts.map(
        function(host, index) {
            var options = {
                method: 'POST',
                uri: host + '/search',
                body: req.body,
                timeout: timeout,
                json: true
            };

            return rp(options)
                .then(function(parsedBody) {
                    if (search_result.length == 0) {
                        search_result = parsedBody;
                    } else {
                        var values = parsedBody;
                        for (var i = 0; i < values.length; i++) {
                            if (search_result.indexOf(values[i]) === -1) {
                                search_result.push(values[i]);
                            }
                        }
                        search_result.sort();
                    }

                    return search_result;
                })
                .catch(function(err) {
                    return err;
                });
        }
    );

    Promise.all(results).then(function(value) {
        setCORSHeaders(res);
        res.json(search_result);
        res.end();
    }, reason => {
        console.log(reason)
        res.status(500).send(reason);
    });
});
*/
app.all('/query', function(req, res) {
    console.log(curlify(req, req.body));
    var data = req.body;
    var from = 'now';
    var to = 'now+6';
    var interval = '30s';
    var intervalMS = 30000;
    var maxDataPoints = 50;
    var datapoints = [];
    var resp = [];
    if (data != null && data.range != null && data.range.from != null) {
        from = data.range.from;
    }
    if (data != null && data.range != null && data.range.to != null) {
        to = data.range.to;
    }
    if (data != null && data.interval != null) {
        interval = data.interval;
    }
    if (data != null && data.intervalMS != null) {
        intervalMS = data.intervalMS;
    }
    if (data != null && data.maxDataPoints != null) {
        maxDataPoints = data.maxDataPoints;
    }
    from = getTime(from);
    to = getTime(to);
    interval = getTimeInterval(interval);

    for (var i = 0; i < data.targets.length; i++) {
        var target = data.targets[i].target;
        target = target.replace(/\s/g, '');
        if (target.indexOf('sin') !== -1) {
            datapoints = sin(from, to, interval, maxDataPoints, target);
        } else if (target.indexOf('const') !== -1) {
            datapoints = cons(from, to, interval, maxDataPoints, target);
            target = 'const';
        } else if (target.indexOf('random') !== -1) {
            datapoints = random(from, to, interval, maxDataPoints, target);
        } else if (target.indexOf('saws') !== -1) {
            datapoints = saws(from, to, interval, maxDataPoints, target);
        }
        var obj = {
            "target": target,
            "datapoints": datapoints
        };
        resp.push(obj);
    }
    setCORSHeaders(res);
    res.json(resp);
    res.end();
});

/**
 * Funcion que dibuja una sierra
 */ 
function saws(from, to, interval, maxDataPoints, target) {
    var datapoints = [];
    var min = 0;
    var max = 1;
    var variable = 0.25;
    var value = min;
    var values = getValuesOperations(target, 'saws');

    if (values == null) {
        if (interval == 20000) {
            interval = interval * 20;
        }
    } else {
        var numbers = getNumbers(values);
        if (numbers.length > 0) {
            min = parseFloat(numbers[0]);
            value = min;
        }
        if (numbers.length > 1) {
            max = parseFloat(numbers[1]);
        }
        if (numbers.length >= 2) {
            variable = parseFloat(numbers[2]);
        }
    }

    for(var i = 0; i < maxDataPoints; i++) {
        datapoints.push([value, from]);
        if (value >= max) {
            value = min;
            datapoints.push([value, from]);
            i++;		
        }
        value += variable;
        from = from + interval;
    }
    
    return datapoints;
}

/**
 * Funcion que genera puntos random
 */ 
function random(from, to, interval, maxDataPoints, target) {
    var datapoints = [];
    var min = 0;
    var max = 1;
    var values = getValuesOperations(target, 'random');

    if (values == null) {
        if (interval == 20000) {
            interval = interval * 20;
        }
    } else {
        var numbers = getNumbers(values);	
        if (numbers.length > 0) {
            min = parseFloat(numbers[0]);
        }
        if (numbers.length >= 1) {
            max = parseFloat(numbers[1]);
        }
    }
    
    for(var i = 0; i < maxDataPoints; i++) {
        datapoints.push([Math.floor(Math.random()*(max-min+1))+min, from]);
        from = from + interval;
    }
    
    return datapoints;
}

/**
 * Funcion que genera una constante
 */ 
function cons(from, to, interval, maxDataPoints, target) {
    var datapoints = [];
    var values = getValuesOperations(target, 'const');
    
    for(var i = 0; i < maxDataPoints; i++) {
        if (values == null) {
            datapoints.push([1, from]);
        } else {
            datapoints.push([values, from]);
        }
        from = from + interval;
    }
    
    return datapoints;
}

/**
 * Funcion que dibuja un seno
 */ 
function sin(from, to, interval, maxDataPoints, target) {
    var datapoints = [];
    var values = getValuesOperations(target, 'sin');
    var variable = values == null ? '' : getVariable(values);

    for(var i = 0; i < maxDataPoints; i++) {
        if (values == null) {
            datapoints.push([Math.sin(from), from]);
        } else {
            datapoints.push([Math.sin(eval(values.replace(variable, from))), from]);
        }
        from = from + interval;
    }
    
    return datapoints;
}

/**
 * Obtiene el conjunto de parametros que se recibieron.
 */ 
function getValuesOperations(target, func) {
    var rx = new RegExp(func + "\\((.*)\\)");
    var arr = rx.exec(target);
    if (arr != null && arr.length > 0) {
        return arr[1];
    } else {
        return null;
    }
}

/**
 * Obtiene el nombre de la variable que se paso como parametro.
 */ 
function getVariable(parameter) {
    var rx = /[a-zA-Z]*/g;
    var resp = rx.exec(parameter);
    return resp;
}

/**
 * Obtiene los valores de los parametros que se reciben.
 */ 
function getNumbers(parameters) {
    var arr = parameters.split(',');
    if (arr != null && arr.length > 0) {
        return arr;
    } else {
        return null;
    }
}

/**
 * Obtiene los milisegundos a partir del valor pasado como parametro.
 * Se puede sumar o restar valorres en horas
 */ 
function getTime(value) {
    if (value.indexOf('now') !== -1) {
        var time = new Date().getTime();
        if (value.indexOf('+') !== -1) {
            var tmp = value.split('+');
	    if (tmp.length() > 0) {
                value = time + (tmp[1] * 3600000);
            } else {
                value = time;
	    }
        } else if (to.indexOf('-') !== -1) {
            var tmp = value.split('-');
	    if (tmp.length() > 0) {
                value = time - (tmp[1] * 3600000);
            } else {
                value = time;
	    }
        } else {
            value = time;
        }
    } else {
	// parseo el valor recibido
        value = new Date(value).getTime();
    }
    return value;
}

/**
 * Se obtiene un intervalo de tiempo en milisegungos a partir de segundos o minutos.
 */ 
function getTimeInterval(value) {
    if (value.indexOf('s') !== -1) {
        value = parseInt(value.replace('s','')) * 1000;
    } else if (value.indexOf('m') !== -1) {
        value = parseInt(value.replace('m','')) * 1000 * 60;
    }
    return value;
}
app.listen(8000);

console.log("Server is listening to port 8000");