import * as express from "express";
import * as http from "http";
import * as https from "https";
import * as SunCalc from "suncalc";
import * as moment from "moment-timezone";
import * as geoTZ from "geo-tz";

import { AdjustmentOptions, GeoCoordinates, TimeData, WateringData, WeatherData } from "../types";
import { WeatherProvider } from "./weatherProviders/WeatherProvider";
const weatherProvider: WeatherProvider = new ( require("./weatherProviders/" + ( process.env.WEATHER_PROVIDER || "OWM" ) ).default )();

// Define regex filters to match against location
const filters = {
	gps: /^[-+]?([1-8]?\d(\.\d+)?|90(\.0+)?),\s*[-+]?(180(\.0+)?|((1[0-7]\d)|([1-9]?\d))(\.\d+)?)$/,
	pws: /^(?:pws|icao|zmw):/,
	url: /^https?:\/\/([\w\.-]+)(:\d+)?(\/.*)?$/,
	time: /(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})([+-])(\d{2})(\d{2})/,
	timezone: /^()()()()()()([+-])(\d{2})(\d{2})/
};

// Enum of available watering scale adjustment methods.
const ADJUSTMENT_METHOD = {
	MANUAL: 0,
	ZIMMERMAN: 1,
	RAIN_DELAY: 2
};

/**
 * Resolves a location description to geographic coordinates.
 * @param location A partial zip/city/country or a coordinate pair.
 * @return A promise that will be resolved with the coordinates of the best match for the specified location, or
 * rejected with an error message if unable to resolve the location.
 */
async function resolveCoordinates( location: string ): Promise< GeoCoordinates > {

	if ( !location ) {
		throw "No location specified";
	}

	if ( filters.pws.test( location ) ) {
		throw "Weather Underground is discontinued";
	} else if ( filters.gps.test( location ) ) {
		const split: string[] = location.split( "," );
		return [ parseFloat( split[ 0 ] ), parseFloat( split[ 1 ] ) ];
	} else {
		// Generate URL for autocomplete request
		const url = "http://autocomplete.wunderground.com/aq?h=0&query=" +
			encodeURIComponent( location );

		let data;
		try {
			data = await httpJSONRequest( url );
		} catch (err) {
			// If the request fails, indicate no data was found.
			throw "An API error occurred while attempting to resolve location";
		}

		// Check if the data is valid
		if ( typeof data.RESULTS === "object" && data.RESULTS.length && data.RESULTS[ 0 ].tz !== "MISSING" ) {

			// If it is, reply with an array containing the GPS coordinates
			return [ parseFloat( data.RESULTS[ 0 ].lat ), parseFloat( data.RESULTS[ 0 ].lon ) ];
		} else {

			// Otherwise, indicate no data was found
			throw "No match found for specified location";
		}
	}
}

/**
 * Makes an HTTP/HTTPS GET request to the specified URL and parses the JSON response body.
 * @param url The URL to fetch.
 * @return A Promise that will be resolved the with parsed response body if the request succeeds, or will be rejected
 * with an error if the request or JSON parsing fails. This error may contain information about the HTTP request or,
 * response including API keys and other sensitive information.
 */
export async function httpJSONRequest(url: string ): Promise< any > {
	try {
		const data: string = await httpRequest(url);
		return JSON.parse(data);
	} catch (err) {
		// Reject the promise if there was an error making the request or parsing the JSON.
		throw err;
	}
}

/**
 * Calculates timezone and sunrise/sunset for the specified coordinates.
 * @param coordinates The coordinates to use to calculate time data.
 * @return The TimeData for the specified coordinates.
 */
function getTimeData( coordinates: GeoCoordinates ): TimeData {
	const timezone = moment().tz( geoTZ( coordinates[ 0 ], coordinates[ 1 ] )[ 0 ] ).utcOffset();
	const tzOffset: number = getTimezone( timezone, true );

	// Calculate sunrise and sunset since Weather Underground does not provide it
	const sunData = SunCalc.getTimes( new Date(), coordinates[ 0 ], coordinates[ 1 ] );

	sunData.sunrise.setUTCMinutes( sunData.sunrise.getUTCMinutes() + tzOffset );
	sunData.sunset.setUTCMinutes( sunData.sunset.getUTCMinutes() + tzOffset );

	return {
		timezone:	timezone,
		sunrise:	( sunData.sunrise.getUTCHours() * 60 + sunData.sunrise.getUTCMinutes() ),
		sunset:		( sunData.sunset.getUTCHours() * 60 + sunData.sunset.getUTCMinutes() )
	};
}

/**
 * Calculates how much watering should be scaled based on weather and adjustment options using the Zimmerman method.
 * @param adjustmentOptions Options to tweak the calculation, or undefined/null if no custom values are to be used.
 * @param wateringData The weather to use to calculate watering percentage.
 * @return The percentage that watering should be scaled by.
 * @throws An error message will be thrown if the watering scale cannot be calculated.
 */
function calculateZimmermanWateringScale( adjustmentOptions: AdjustmentOptions, wateringData: WateringData ): number {

	let humidityBase = 30, tempBase = 70, precipBase = 0;

	// Check to make sure valid data exists for all factors
	if ( !validateValues( [ "temp", "humidity", "precip" ], wateringData ) ) {
		throw "Necessary field(s) were missing from WateringData.";
	}

	// Get baseline conditions for 100% water level, if provided
	if ( adjustmentOptions ) {
		humidityBase = adjustmentOptions.hasOwnProperty( "bh" ) ? adjustmentOptions.bh : humidityBase;
		tempBase = adjustmentOptions.hasOwnProperty( "bt" ) ? adjustmentOptions.bt : tempBase;
		precipBase = adjustmentOptions.hasOwnProperty( "br" ) ? adjustmentOptions.br : precipBase;
	}

	let humidityFactor = ( humidityBase - wateringData.humidity ),
		tempFactor = ( ( wateringData.temp - tempBase ) * 4 ),
		precipFactor = ( ( precipBase - wateringData.precip ) * 200 );

	// Apply adjustment options, if provided, by multiplying the percentage against the factor
	if ( adjustmentOptions ) {
		if ( adjustmentOptions.hasOwnProperty( "h" ) ) {
			humidityFactor = humidityFactor * ( adjustmentOptions.h / 100 );
		}

		if ( adjustmentOptions.hasOwnProperty( "t" ) ) {
			tempFactor = tempFactor * ( adjustmentOptions.t / 100 );
		}

		if ( adjustmentOptions.hasOwnProperty( "r" ) ) {
			precipFactor = precipFactor * ( adjustmentOptions.r / 100 );
		}
	}

	// Apply all of the weather modifying factors and clamp the result between 0 and 200%.
	return Math.floor( Math.min( Math.max( 0, 100 + humidityFactor + tempFactor + precipFactor ), 200 ) );
}

/**
 * Checks if the weather data meets any of the restrictions set by OpenSprinkler. Restrictions prevent any watering
 * from occurring and are similar to 0% watering level. Known restrictions are:
 *
 * - California watering restriction prevents watering if precipitation over two days is greater than 0.1" over the past
 * 48 hours.
 * @param adjustmentValue The adjustment value, which indicates which restrictions should be checked.
 * @param weather Watering data to use to determine if any restrictions apply.
 * @return A boolean indicating if the watering level should be set to 0% due to a restriction.
 */
function checkWeatherRestriction( adjustmentValue: number, weather: WateringData ): boolean {

	const californiaRestriction = ( adjustmentValue >> 7 ) & 1;

	if ( californiaRestriction ) {

		// TODO depending on which WeatherProvider is used, this might be checking if rain is forecasted in th next 24
		// 	hours rather than checking if it has rained in the past 48 hours.
		// If the California watering restriction is in use then prevent watering
		// if more then 0.1" of rain has accumulated in the past 48 hours
		if ( weather.precip > 0.1 ) {
			return true;
		}
	}

	return false;
}

export const getWeatherData = async function( req: express.Request, res: express.Response ) {
	const location: string = getParameter(req.query.loc);

	let coordinates: GeoCoordinates;
	try {
		coordinates = await resolveCoordinates( location );
	} catch (err) {
		res.send(`Error: Unable to resolve location (${err})`);
		return;
	}

	// Continue with the weather request
	const timeData: TimeData = getTimeData( coordinates );
	let weatherData: WeatherData;
	try {
		weatherData = await weatherProvider.getWeatherData( coordinates );
	} catch ( err ) {
		res.send( "Error: " + err );
		return;
	}

	res.json( {
		...timeData,
		...weatherData,
		location: coordinates
	} );
};

// API Handler when using the weatherX.py where X represents the
// adjustment method which is encoded to also carry the watering
// restriction and therefore must be decoded
export const getWateringData = async function( req: express.Request, res: express.Response ) {

	// The adjustment method is encoded by the OpenSprinkler firmware and must be
	// parsed. This allows the adjustment method and the restriction type to both
	// be saved in the same byte.
	let adjustmentMethod: number			= req.params[ 0 ] & ~( 1 << 7 ),
		checkRestrictions: boolean			= ( ( req.params[ 0 ] >> 7 ) & 1 ) > 0,
		adjustmentOptionsString: string		= getParameter(req.query.wto),
		location: string | GeoCoordinates	= getParameter(req.query.loc),
		outputFormat: string				= getParameter(req.query.format),
		remoteAddress: string				= getParameter(req.headers[ "x-forwarded-for" ]) || req.connection.remoteAddress,
		adjustmentOptions: AdjustmentOptions;

	/* A message to include in the response to indicate that the watering scale was not calculated correctly and
	defaulted to 100%. This approach is used for backwards compatibility because older OS firmware versions were
	hardcoded to keep the previous watering scale if the response did not include a watering scale, but newer versions
	might allow for different behaviors. */
	let errorMessage: string = undefined;


	// X-Forwarded-For header may contain more than one IP address and therefore
	// the string is split against a comma and the first value is selected
	remoteAddress = remoteAddress.split( "," )[ 0 ];

	// Parse weather adjustment options
	try {

		// Parse data that may be encoded
		adjustmentOptionsString = decodeURIComponent( adjustmentOptionsString.replace( /\\x/g, "%" ) );

		// Reconstruct JSON string from deformed controller output
		adjustmentOptions = JSON.parse( "{" + adjustmentOptionsString + "}" );
	} catch ( err ) {

		// If the JSON is not valid then abort the claculation
		res.send(`Error: Unable to parse options (${err})`);
		return;
	}

	// Attempt to resolve provided location to GPS coordinates.
	let coordinates: GeoCoordinates;
	try {
		coordinates = await resolveCoordinates( location );
	} catch (err) {
		res.send(`Error: Unable to resolve location (${err})`);
		return;
	}

	// Continue with the weather request
	let timeData: TimeData = getTimeData( coordinates );
	let wateringData: WateringData;
	if ( adjustmentMethod !== ADJUSTMENT_METHOD.MANUAL || checkRestrictions ) {
		try {
			wateringData = await weatherProvider.getWateringData( coordinates );
		} catch ( err ) {
			res.send( "Error: " + err );
			return;
		}
	}

	let scale = -1,	rainDelay = -1;

	if ( adjustmentMethod === ADJUSTMENT_METHOD.ZIMMERMAN ) {
		try {
			scale = calculateZimmermanWateringScale( adjustmentOptions, wateringData );
		} catch ( err ) {
			// Default to a scale of 100% if the scale can't be calculated.
			scale = 100;
			errorMessage = err;
		}
	}

	if (wateringData) {
		// Check for any user-set restrictions and change the scale to 0 if the criteria is met
		if (checkWeatherRestriction(req.params[0], wateringData)) {
			scale = 0;
		}

		// If any weather adjustment is being used, check the rain status
		if ( adjustmentMethod > ADJUSTMENT_METHOD.MANUAL && wateringData.raining ) {

			// If it is raining and the user has weather-based rain delay as the adjustment method then apply the specified delay
			if ( adjustmentMethod === ADJUSTMENT_METHOD.RAIN_DELAY ) {

				rainDelay = ( adjustmentOptions && adjustmentOptions.hasOwnProperty( "d" ) ) ? adjustmentOptions.d : 24;
			} else {
				// Temporarily disabled since OWM forecast data is checking if rain is forecasted for 3 hours in the future.
				// For any other adjustment method, apply a scale of 0 (as the scale will revert when the rain stops)
				// scale = 0;
			}
		}
	}

	const data = {
		scale:		scale,
		rd:			rainDelay,
		tz:			getTimezone( timeData.timezone, undefined ),
		sunrise:	timeData.sunrise,
		sunset:		timeData.sunset,
		eip:		ipToInt( remoteAddress ),
		rawData:	undefined,
		error:		errorMessage
	};

	if ( adjustmentMethod > ADJUSTMENT_METHOD.MANUAL ) {
		data.rawData = {
			h: wateringData ? Math.round( wateringData.humidity * 100) / 100 : null,
			p: wateringData ? Math.round( wateringData.precip * 100 ) / 100 : null,
			t: wateringData ? Math.round( wateringData.temp * 10 ) / 10 : null,
			raining: wateringData ? ( wateringData.raining ? 1 : 0 ) : null
		};
	}

	// Return the response to the client in the requested format
	if ( outputFormat === "json" ) {
		res.json( data );
	} else {
		res.send(	"&scale="		+	data.scale +
			"&rd="			+	data.rd +
			"&tz="			+	data.tz +
			"&sunrise="		+	data.sunrise +
			"&sunset="		+	data.sunset +
			"&eip="			+	data.eip +
			( data.rawData ? "&rawData=" + JSON.stringify( data.rawData ) : "" ) +
			( errorMessage ? "&error=" + encodeURIComponent( errorMessage ) : "" )
		);
	}

};

/**
 * Makes an HTTP/HTTPS GET request to the specified URL and returns the response body.
 * @param url The URL to fetch.
 * @return A Promise that will be resolved the with response body if the request succeeds, or will be rejected with an
 * error if the request fails or returns a non-200 status code. This error may contain information about the HTTP
 * request or, response including API keys and other sensitive information.
 */
async function httpRequest( url: string ): Promise< string > {
	return new Promise< any >( ( resolve, reject ) => {

		const splitUrl: string[] = url.match( filters.url );
		const isHttps = url.startsWith("https");

		const options = {
			host: splitUrl[ 1 ],
			port: splitUrl[ 2 ] || ( isHttps ? 443 : 80 ),
			path: splitUrl[ 3 ]
		};

		( isHttps ? https : http ).get( options, ( response ) => {
			if ( response.statusCode !== 200 ) {
				reject( `Received ${ response.statusCode } status code for URL '${ url }'.` );
				return;
			}

			let data = "";

			// Reassemble the data as it comes in
			response.on( "data", ( chunk ) => {
				data += chunk;
			} );

			// Once the data is completely received, resolve the promise
			response.on( "end", () => {
				resolve( data );
			} );
		} ).on( "error", ( err ) => {

			// If the HTTP request fails, reject the promise
			reject( err );
		} );
	} );
}

/**
 * Checks if the specified object contains numeric values for each of the specified keys.
 * @param keys A list of keys to validate exist on the specified object.
 * @param obj The object to check.
 * @return A boolean indicating if the object has numeric values for all of the specified keys.
 */
function validateValues( keys: string[], obj: object ): boolean {
	let key: string;

	// Return false if the object is null/undefined.
	if ( !obj ) {
		return false;
	}

	for ( key in keys ) {
		if ( !keys.hasOwnProperty( key ) ) {
			continue;
		}

		key = keys[ key ];

		if ( !obj.hasOwnProperty( key ) || typeof obj[ key ] !== "number" || isNaN( obj[ key ] ) || obj[ key ] === null || obj[ key ] === -999 ) {
			return false;
		}
	}

	return true;
}

/**
 * Converts a timezone to an offset in minutes or OpenSprinkler encoded format.
 * @param time A time string formatted in ISO-8601 or just the timezone.
 * @param useMinutes Indicates if the returned value should be in minutes of the OpenSprinkler encoded format.
 * @return The offset of the specified timezone in either minutes or OpenSprinkler encoded format (depending on the
 * value of useMinutes).
 */
function getTimezone( time: number | string, useMinutes: boolean = false ): number {

	let hour, minute;

	if ( typeof time === "number" ) {
		hour = Math.floor( time / 60 );
		minute = time % 60;
	} else {

		// Match the provided time string against a regex for parsing
		let splitTime = time.match( filters.time ) || time.match( filters.timezone );

		hour = parseInt( splitTime[ 7 ] + splitTime[ 8 ] );
		minute = parseInt( splitTime[ 9 ] );
	}

	if ( useMinutes ) {
		return ( hour * 60 ) + minute;
	} else {

		// Convert the timezone into the OpenSprinkler encoded format
		minute = ( minute / 15 >> 0 ) / 4;
		hour = hour + ( hour >= 0 ? minute : -minute );

		return ( ( hour + 12 ) * 4 ) >> 0;
	}
}

/**
 * Converts an IP address string to an integer.
 * @param ip The string representation of the IP address.
 * @return The integer representation of the IP address.
 */
function ipToInt( ip: string ): number {
    const split = ip.split( "." );
    return ( ( ( ( ( ( +split[ 0 ] ) * 256 ) + ( +split[ 1 ] ) ) * 256 ) + ( +split[ 2 ] ) ) * 256 ) + ( +split[ 3 ] );
}

/**
 * Returns a single value for a header/query parameter. If passed a single string, the same string will be returned. If
 * an array of strings is passed, the first value will be returned. If this value is null/undefined, an empty string
 * will be returned instead.
 * @param parameter An array of parameters or a single parameter value.
 * @return The first element in the array of parameter or the single parameter provided.
 */
function getParameter( parameter: string | string[] ): string {
	if ( Array.isArray( parameter ) ) {
		parameter = parameter[0];
	}

	// Return an empty string if the parameter is undefined.
	return parameter || "";
}