"use strict";

import haversine from 'haversine-distance';

import shuffle_fisher_yates from '../Helpers/FisherYates.mjs';

import {
	normalise_lat,
	normalise_lng,
	normalise_rssi,
	normalise_gateway_distance,
} from '../../common/Normalisers.mjs';

class DatasetFetcher {
	constructor({ settings, log, GatewayRepo, RSSIRepo, ReadingRepo }) {
		this.settings = settings;
		this.l = log;
		this.repo_gateway = GatewayRepo;
		this.repo_rssi = RSSIRepo;
		this.repo_reading = ReadingRepo;
	}
	
	fetch_all(gateway_id) {
		let gateway_location = this.repo_gateway.get_by_id(gateway_id);
		
		let result = [];
		for(let rssi of this.repo_rssi.iterate_gateway(gateway_id)) {
			result.push({
				input: {
					latitude: rssi.latitude,
					longitude: rssi.longitude,
					distance: haversine(gateway_location, rssi)
				},
				output: [
					rssi.rssi
				]
			});
		}
		
		for(let reading of this.repo_reading.iterate_unreceived()) {
			result.push({
				input: {
					latitude: reading.latitude,
					longitude: reading.longitude,
					distance: haversine(gateway_location, reading)
				},
				output: [ -150 ]
			});
		}
		shuffle_fisher_yates(result);
		
		if(this.settings.ai.do_zap_false_negatives) {
			let zap_count = this.zap_false_negatives(result, this.settings.ai.false_negative_zap_radius);
			this.l.log(`[DatasetFetcher] Zapped ${zap_count} false negatives with a radius of ${this.settings.ai.false_negative_zap_radius}m.`);
		}
		
		for(let item of result) {
			item.input.latitude = normalise_lat(item.input.latitude);
			item.input.longitude = normalise_lng(item.input.longitude);
			item.input.distance = normalise_gateway_distance(item.input.distance);
			item.output[0] = normalise_rssi(item.output[0]);
		}
		
		return result;
	}
	
	zap_false_negatives(readings_raw, max_distance_metres) {
		let items_zapped = 0;
		
		for(let next_item of readings_raw) {
			// Only zap for readings where we got a signal
			if(next_item.output[0] <= -150) // -150: codename for no signal
				continue;
			
			// console.log(next_item);
			
			// Store a list of items to zap, because changing the length of the 
			// array while we're iterating it is a recipe for disaster
			let items_to_zap = [];
			
			for(let comp_item of readings_raw) {
				// Avoid zapping readings where we got a signal
				if(comp_item.output[0] > -150)
					continue;
				
				let distance = haversine(
					next_item.input,
					comp_item.input
				);
				if(isNaN(distance))
					throw new Error(`Error: Got NaN when checking zapping distance.`);
				
				if(distance < max_distance_metres) {
					// console.log(`Zap! (${distance})`);
					items_to_zap.push(comp_item);
				}
			}
			
			items_zapped += items_to_zap.length;
			for(let next_item of items_to_zap) {
				readings_raw.splice(readings_raw.indexOf(next_item), 1);
			}
		}
		
		return items_zapped;
	}
}


export default DatasetFetcher;