import type { FlightParameters } from '../../src/lib/domain/scenario';

/**
 * Generate a fake prediction trajectory. We fake an ascent phase that climbs
 * to burst_altitude at ascent_rate, then a descent at descent_rate. The
 * ground track drifts roughly east as a function of altitude to loosely
 * mimic wind drift.
 */
export function fakePrediction(params: FlightParameters & { launch_datetime: string }) {
	const launch = new Date(params.launch_datetime);
	const ascentDurationSec = Math.round(
		(params.burst_altitude - params.launch_altitude) / params.ascent_rate,
	);
	const descentDurationSec = Math.round(params.burst_altitude / params.descent_rate);
	const stepSec = 30;

	const ascent: unknown[] = [];
	for (let t = 0; t <= ascentDurationSec; t += stepSec) {
		const alt = params.launch_altitude + t * params.ascent_rate;
		ascent.push({
			altitude: alt,
			datetime: new Date(launch.getTime() + t * 1000).toISOString(),
			latitude: params.launch_latitude + t * 0.00002,
			longitude: params.launch_longitude + t * 0.00005,
		});
	}

	const descent: unknown[] = [];
	const burstTime = launch.getTime() + ascentDurationSec * 1000;
	const burstLat = params.launch_latitude + ascentDurationSec * 0.00002;
	const burstLng = params.launch_longitude + ascentDurationSec * 0.00005;
	for (let t = 0; t <= descentDurationSec; t += stepSec) {
		const alt = Math.max(0, params.burst_altitude - t * params.descent_rate);
		descent.push({
			altitude: alt,
			datetime: new Date(burstTime + t * 1000).toISOString(),
			latitude: burstLat + t * 0.00001,
			longitude: burstLng + t * 0.00003,
		});
	}

	return {
		result: {
			metadata: {
				start_datetime: new Date(launch.getTime() - 3600 * 1000).toISOString(),
				complete_datetime: new Date(
					burstTime + descentDurationSec * 1000,
				).toISOString(),
			},
			prediction: [
				{ stage: 'ascent', trajectory: ascent },
				{ stage: 'descent', trajectory: descent },
			],
		},
	};
}