/// Any lower than this, and the target position of the fish is considered null
#define FISH_TARGET_MIN_DISTANCE 6
/// The friction applied to fish jumps, so that it decelerates over time
#define FISH_FRICTION_MULT 0.9
/// Used to decide whether the fish can jump in a certain direction
#define FISH_SHORT_JUMP_MIN_DISTANCE 100
/// The maximum distance for a short jump
#define FISH_SHORT_JUMP_MAX_DISTANCE 200

///Fish movements are simple datums, generated by the fishing minigame, that represent how the fish moves suring the minigame.
/datum/fish_movement
	/// The minigame that spawned us
	var/datum/fishing_challenge/master
	/// How many times move_fish() has been called
	var/times_fired = 0
	/// How likely the fish is to perform a standard jump, then multiplied by difficulty
	var/short_jump_chance = 2.25
	/// How likely the fish is to perform a long jump, then multiplied by difficulty
	var/long_jump_chance = 0.0625
	/// The speed limit for the short jump
	var/short_jump_velocity_limit = 400
	/// The speed limit for the long jump
	var/long_jump_velocity_limit = 200
	/// The current speed limit used
	var/current_velocity_limit
	/// The base velocity of the fish, which may affect jump distances and falling speed.
	var/fish_idle_velocity = 0
	/// A position on the slider the fish wants to get to
	var/target_position
	/// If true, the fish can jump while a target position is set, thus overriding it
	var/can_interrupt_move = TRUE
	/// The current speed the fish is moving at
	var/fish_velocity = 0

/datum/fish_movement/New(datum/fishing_challenge/master)
	src.master = master

/**
 * Proc that adjusts movement values to the difficulty of the minigame.
 * The operations can be a tad complex, but basically it ensures that jump
 * chances with a probability higher than 1% increase in a smooth curve so that
 * they still reach 100% prob when the difficulty peakes.
 */
/datum/fish_movement/proc/adjust_to_difficulty()
	var/square_angle_rad = TORADIANS(90)
	var/zero_one_difficulty = master.difficulty/100
	if(short_jump_chance > 1)
		short_jump_chance = (zero_one_difficulty**(square_angle_rad-TORADIANS(arctan(short_jump_chance * 1/square_angle_rad))))*100
	else
		short_jump_chance *= master.difficulty
	if(long_jump_chance > 1)
		long_jump_chance = (zero_one_difficulty**(square_angle_rad-TORADIANS(arctan(long_jump_chance * 1/square_angle_rad))))*100
	else
		long_jump_chance *= master.difficulty

/datum/fish_movement/proc/reset_difficulty_values()
	short_jump_chance = initial(short_jump_chance)
	long_jump_chance = initial(long_jump_chance)

///The main proc, called by minigame every SSfishing tick while it's in the 'active' phase.
/datum/fish_movement/proc/move_fish(seconds_per_tick)
	times_fired++
	/**
	 * The jump chances are meant to run every odd tick (each every decisecond)
	 * We cannot do it every tick because the fish would be jumpier than intended
	 * and we cannot cut the chances in half to fit on each tick, because the maximum probability
	 *  would go from 100% to 75%.
	 */
	var/can_roll = times_fired % 2

	var/long_chance = long_jump_chance * seconds_per_tick * (1/seconds_per_tick)
	var/short_chance = short_jump_chance * seconds_per_tick * (1/seconds_per_tick)

	// If we have the target but we're close enough, mark as target reached
	if(abs(target_position - master.fish_position) < FISH_TARGET_MIN_DISTANCE)
		target_position = null

	// Switching to new long jump target can interrupt any other
	if(can_roll && (can_interrupt_move || isnull(target_position)) && prob(long_chance))
		/**
		 * Move at least 0.75 to full of the availible bar in given direction,
		 * and more likely to move in the direction where there's more space
		 */
		var/distance_from_top = FISHING_MINIGAME_AREA - master.fish_position - master.fish_height
		var/distance_from_bottom = master.fish_position
		var/top_chance
		if(distance_from_top < FISH_SHORT_JUMP_MIN_DISTANCE)
			top_chance = 0
		else
			top_chance = (distance_from_top/max(distance_from_bottom, 1)) * 100
		var/new_target = master.fish_position
		if(prob(top_chance))
			new_target += distance_from_top * rand(75, 100)/100
		else
			new_target -= distance_from_bottom * rand(75, 100)/100
		target_position = round(new_target)
		current_velocity_limit = long_jump_velocity_limit

	// Move towards target
	if(!isnull(target_position))
		var/distance = target_position - master.fish_position
		// about 5 at diff 15 , 10 at diff 30, 30 at diff 100
		var/acceleration_mult = get_acceleration(seconds_per_tick)
		var/target_acceleration = distance * acceleration_mult * seconds_per_tick

		if(fish_idle_velocity)
			var/idle_velocity = fish_idle_velocity
			var/abs_idle_vel = abs(idle_velocity)
			//Make sure idle velocity doesn't manage to halt fish to a grind and getting them unable to move.
			//First, check if the directions of the two forces are oppositve
			if((idle_velocity / abs_idle_vel) != (target_acceleration / abs(target_acceleration)))
				//Then, calculate the ratio between absolute idle velocity and halved acceleration multiplier.
				var/halved_ratio = (acceleration_mult * 0.5) / abs_idle_vel
				/**
				 * If the idle velocity is more than half the acceleration,
				 * proceed to use powers, for diminishing loss of acceleration per additional unit of idle velocity.
				 * This way you never reach 0 acceleration while allowing more extreme values to keep lowering it.
				 */
				if(halved_ratio < 1)
					var/power = min(halved_ratio + 0.5, 1)
					target_acceleration *= 1 - (halved_ratio^power)
				/**
				 * Otherwise we add the idle velocity (which we know is of opposite sign and
				 * has an absolute value between 0.ε and 0.5) to the target velocity
				 */
				else
					target_acceleration += idle_velocity

		fish_velocity = fish_velocity * FISH_FRICTION_MULT + target_acceleration

	else if(can_roll && prob(short_chance))
		var/distance_from_top = FISHING_MINIGAME_AREA - master.fish_position - master.fish_height
		var/distance_from_bottom = master.fish_position
		var/jump_length
		if(distance_from_top >= FISH_SHORT_JUMP_MIN_DISTANCE)
			jump_length = rand(FISH_SHORT_JUMP_MIN_DISTANCE, FISH_SHORT_JUMP_MAX_DISTANCE)
		if(distance_from_bottom >= FISH_SHORT_JUMP_MIN_DISTANCE && (!jump_length || prob(50)))
			jump_length = -rand(FISH_SHORT_JUMP_MIN_DISTANCE, FISH_SHORT_JUMP_MAX_DISTANCE)
		target_position = clamp(master.fish_position + jump_length, 0, FISHING_MINIGAME_AREA - master.fish_height)
		current_velocity_limit = short_jump_velocity_limit

	fish_velocity = clamp(fish_velocity, -current_velocity_limit, current_velocity_limit)
	set_fish_position(seconds_per_tick)

///Proc that returns the acceleration of the fish during the minigame.
/datum/fish_movement/proc/get_acceleration(seconds_per_tick)
	return 0.3 * master.difficulty + 0.5

///Called at the end of move_fish(), for updating the position of the fish in the fishing minigame.
/datum/fish_movement/proc/set_fish_position(seconds_per_tick)
	master.fish_position = clamp(master.fish_position + fish_velocity * seconds_per_tick, 0, FISHING_MINIGAME_AREA - master.fish_height)

///Generic fish movement datum that only performs slow, uninterrupted long jumps
/datum/fish_movement/slow
	short_jump_chance = 0
	long_jump_chance = 1.5
	long_jump_velocity_limit = 150
	can_interrupt_move = FALSE

///Generic fish movement datum with triple the short jump chance.
/datum/fish_movement/zippy
	short_jump_chance = parent_type::short_jump_chance * 3

///fish movement datum that progressively gets faster until acceleration and velocity are double the starting ones.
/datum/fish_movement/accelerando
	///The jump velocity to add each tick
	var/short_jump_vel_add
	///The long jump velocity to add each tick
	var/long_jump_vel_add
	///Time to reach full speed, in seconds.
	var/accel_time_cap = 30

/datum/fish_movement/accelerando/move_fish(seconds_per_tick)
	var/seconds_elapsed = (times_fired * seconds_per_tick)
	if(seconds_elapsed >= accel_time_cap)
		return ..()
	if(!times_fired) //First tick, cache the initial jump velocities
		short_jump_vel_add = short_jump_velocity_limit/accel_time_cap
		long_jump_vel_add = long_jump_velocity_limit/accel_time_cap
		return ..()

	if(current_velocity_limit)
		var/vel_add = current_velocity_limit == short_jump_velocity_limit ? short_jump_vel_add : long_jump_vel_add
		current_velocity_limit += round(vel_add * seconds_per_tick, 0.01)

	short_jump_velocity_limit += round(short_jump_vel_add * seconds_per_tick, 0.01)
	long_jump_velocity_limit += round(long_jump_vel_add * seconds_per_tick, 0.01)
	return ..()

/datum/fish_movement/accelerando/get_acceleration(seconds_per_tick)
	var/acceleration = ..()
	return acceleration + min(acceleration, acceleration * times_fired * seconds_per_tick / accel_time_cap)

/datum/fish_movement/accelerando/set_fish_position(seconds_per_tick)
	fish_velocity = round(fish_velocity)
	return ..()

///Fish movement datum that updates the fish position twice per second.
/datum/fish_movement/choppy
	///We keep of the theorical fish position to eventually use
	var/faux_position = 0

/datum/fish_movement/choppy/set_fish_position(seconds_per_tick)
	faux_position = clamp(faux_position + fish_velocity * seconds_per_tick, 0, FISHING_MINIGAME_AREA - master.fish_height)
	if(!((times_fired * SSfishing.wait) % (0.5 SECONDS)))
		master.fish_position = faux_position

///Fish movement datum that weakly pushes the fish up and then down with greater force once it reaches the top of the minigame.
/datum/fish_movement/plunger
	///Is the fish plunging to the bottom of the minigame area, or should it swim up?
	var/is_plunging = TRUE
	///The added idle velocity when plunging
	var/plunging_speed = -22

/datum/fish_movement/plunger/adjust_to_difficulty()
	. = ..()
	//Adjust the fleeing velocity, up to five times the initial value.
	plunging_speed += round(plunging_speed * master.difficulty * 0.03)
	fish_idle_velocity += plunging_speed //so it can be safely subtracted if the fish starts at the bottom.

/datum/fish_movement/plunger/reset_difficulty_values()
	. = ..()
	if(is_plunging)
		fish_idle_velocity -= plunging_speed
	plunging_speed = initial(plunging_speed)

/datum/fish_movement/plunger/move_fish(seconds_per_tick)
	var/fish_area = FISHING_MINIGAME_AREA - master.fish_height
	if(is_plunging)
		if(target_position > master.fish_position) //nothing should stop us from plunging.
			target_position = null
		var/dist_bot_percent = master.fish_position/fish_area
		if(dist_bot_percent <= 0.04)
			fish_idle_velocity -= plunging_speed
			is_plunging = FALSE
	else
		var/dist_top_percent = (fish_area - master.fish_position)/fish_area
		if(dist_top_percent <= 0.04)
			fish_idle_velocity += plunging_speed
			is_plunging = TRUE

	return ..()


#undef FISH_TARGET_MIN_DISTANCE
#undef FISH_FRICTION_MULT
#undef FISH_SHORT_JUMP_MIN_DISTANCE
#undef FISH_SHORT_JUMP_MAX_DISTANCE