const placementPms = [1000, 400, 250, 150, 100, 90, 80, 70, 60, 50, 40, 30, 25, 20, 15, 10, 10, 10] as const;

/**
 * Calculate base fans for a given placement in a race.
 * @param winBase Base fans for a win, as displayed in the race menu
 * @param finishOrder Placement of the trainee, with winner being 1
 * @returns Base fans for the race and placement together
 */
export function baseFans(winBase: number, finishOrder: number): number {
	return Math.round(winBase * placementPms[finishOrder - 1] / 1000);
}

const margins = [
	[0.75, 0.0, 0.09],
	[2.5, 0.02, 0.06],
	[4, 0.04, 0.04],
	[6, 0.06, 0.02],
	[Infinity, 0.09, 0.0],
] as const;

/**
 * Calculate fans gained from a career race due to the margin of the finish.
 * @param baseFans Base fans from the race and finish order
 * @param finishOrder Placement of the trainee, with winner being 1
 * @param margin Margin in lengths between the trainee and second if a win, or the winner and trainee if a loss
 * @returns Fans gained due to finish margin
 */
export function marginFans(baseFans: number, finishOrder: number, margin: number): number {
	if (finishOrder > 5) {
		return 0;
	}
	const [, wb, lb] = margins.find(([m]) => margin <= m)!;
	const b = finishOrder === 1 ? wb : lb;
	return Math.floor(baseFans * b);
}

const skills = [
	[0, 0.0],
	[3, 0.02],
	[6, 0.03],
	[9, 0.05],
	[Infinity, 0.08],
] as const;

/**
 * Calculate the fans gained from a career race due to skills activated.
 * @param baseFans Base fans from the race and finish order
 * @param skillsActivated Number of skills the trainee activated during the race
 * @returns Fans gained due to skill activations
 */
export function skillFans(baseFans: number, skillsActivated: number): number {
	const [, b] = skills.find(([n]) => skillsActivated <= n)!;
	return Math.floor(baseFans * b);
}

/**
 * Calculate fan gain from a career race.
 * @param baseFans Base fans from the race and finish order
 * @param marginFans Fans gained due to finish margin
 * @param skillFans Fans gained due to skill activations
 * @param fanBonus Total fan bonus from support cards
 * @param itemBonus Fan bonus from items (MANT glowsticks)
 * @returns Total fans gained
 */
export function gained(baseFans: number, marginFans: number, skillFans: number, fanBonus: number, itemBonus?: number): number {
	const f = baseFans + marginFans + skillFans;
	const s = Math.fround(f * Math.fround(1 + fanBonus / 100));
	const p = Math.exp((4 - Math.floor(Math.log10(s))) * Math.LN10);
	// Add half a significant figure to account for precision.
	const d = Math.floor(Math.round(s * p + 5e-6) / p + 5e-6);
	const b = itemBonus ?? 0;
	return Math.floor(d * (1 + b / 100));
}