#include "player.qh"
#include "../triggers/include.qh"
#include "../viewloc.qh"

#ifdef SVQC

#include <server/miscfunctions.qh>
#include "../triggers/trigger/viewloc.qh"

// client side physics
bool Physics_Valid(string thecvar)
{
	return autocvar_g_physics_clientselect && thecvar != "" && thecvar && && thecvar != "default" strhasword(autocvar_g_physics_clientselect_options, thecvar);
}

float Physics_ClientOption(entity this, string option, float defaultval)
{
	if(IS_REAL_CLIENT(this) && Physics_Valid(this.cvar_cl_physics))
	{
		string s = strcat("g_physics_", this.cvar_cl_physics, "_", option);
		if(cvar_type(s) & CVAR_TYPEFLAG_EXISTS)
			return cvar(s);
	}
	if(autocvar_g_physics_clientselect && autocvar_g_physics_clientselect_default)
	{
		string s = strcat("g_physics_", autocvar_g_physics_clientselect_default, "_", option);
		if(cvar_type(s) & CVAR_TYPEFLAG_EXISTS)
			return cvar(s);
	}
	return defaultval;
}

void Physics_UpdateStats(entity this, float maxspd_mod)
{
	STAT(MOVEVARS_AIRACCEL_QW, this) = AdjustAirAccelQW(Physics_ClientOption(this, "airaccel_qw", autocvar_sv_airaccel_qw), maxspd_mod);
	STAT(MOVEVARS_AIRSTRAFEACCEL_QW, this) = (Physics_ClientOption(this, "airstrafeaccel_qw", autocvar_sv_airstrafeaccel_qw))
		? AdjustAirAccelQW(Physics_ClientOption(this, "airstrafeaccel_qw", autocvar_sv_airstrafeaccel_qw), maxspd_mod)
		: 0;
	STAT(MOVEVARS_AIRSPEEDLIMIT_NONQW, this) = Physics_ClientOption(this, "airspeedlimit_nonqw", autocvar_sv_airspeedlimit_nonqw) * maxspd_mod;
	STAT(MOVEVARS_MAXSPEED, this) = Physics_ClientOption(this, "maxspeed", autocvar_sv_maxspeed) * maxspd_mod; // also slow walking

	STAT(PL_MIN, this) = autocvar_sv_player_mins;
	STAT(PL_MAX, this) = autocvar_sv_player_maxs;
	STAT(PL_VIEW_OFS, this) = autocvar_sv_player_viewoffset;
	STAT(PL_CROUCH_MIN, this) = autocvar_sv_player_crouch_mins;
	STAT(PL_CROUCH_MAX, this) = autocvar_sv_player_crouch_maxs;
	STAT(PL_CROUCH_VIEW_OFS, this) = autocvar_sv_player_crouch_viewoffset;

	// old stats
	// fix some new settings
	STAT(MOVEVARS_AIRACCEL_QW_STRETCHFACTOR, this) = Physics_ClientOption(this, "airaccel_qw_stretchfactor", autocvar_sv_airaccel_qw_stretchfactor);
	STAT(MOVEVARS_MAXAIRSTRAFESPEED, this) = Physics_ClientOption(this, "maxairstrafespeed", autocvar_sv_maxairstrafespeed);
	STAT(MOVEVARS_MAXAIRSPEED, this) = Physics_ClientOption(this, "maxairspeed", autocvar_sv_maxairspeed);
	STAT(MOVEVARS_AIRSTRAFEACCELERATE, this) = Physics_ClientOption(this, "airstrafeaccelerate", autocvar_sv_airstrafeaccelerate);
	STAT(MOVEVARS_WARSOWBUNNY_TURNACCEL, this) = Physics_ClientOption(this, "warsowbunny_turnaccel", autocvar_sv_warsowbunny_turnaccel);
	STAT(MOVEVARS_AIRACCEL_SIDEWAYS_FRICTION, this) = Physics_ClientOption(this, "airaccel_sideways_friction", autocvar_sv_airaccel_sideways_friction);
	STAT(MOVEVARS_AIRCONTROL, this) = Physics_ClientOption(this, "aircontrol", autocvar_sv_aircontrol);
	STAT(MOVEVARS_AIRCONTROL_POWER, this) = Physics_ClientOption(this, "aircontrol_power", autocvar_sv_aircontrol_power);
	STAT(MOVEVARS_AIRCONTROL_BACKWARDS, this) = Physics_ClientOption(this, "aircontrol_backwards", autocvar_sv_aircontrol_backwards);
	STAT(MOVEVARS_AIRCONTROL_PENALTY, this) = Physics_ClientOption(this, "aircontrol_penalty", autocvar_sv_aircontrol_penalty);
	STAT(MOVEVARS_WARSOWBUNNY_AIRFORWARDACCEL, this) = Physics_ClientOption(this, "warsowbunny_airforwardaccel", autocvar_sv_warsowbunny_airforwardaccel);
	STAT(MOVEVARS_WARSOWBUNNY_TOPSPEED, this) = Physics_ClientOption(this, "warsowbunny_topspeed", autocvar_sv_warsowbunny_topspeed);
	STAT(MOVEVARS_WARSOWBUNNY_ACCEL, this) = Physics_ClientOption(this, "warsowbunny_accel", autocvar_sv_warsowbunny_accel);
	STAT(MOVEVARS_WARSOWBUNNY_BACKTOSIDERATIO, this) = Physics_ClientOption(this, "warsowbunny_backtosideratio", autocvar_sv_warsowbunny_backtosideratio);
	STAT(MOVEVARS_FRICTION, this) = Physics_ClientOption(this, "friction", autocvar_sv_friction);
	STAT(MOVEVARS_ACCELERATE, this) = Physics_ClientOption(this, "accelerate", autocvar_sv_accelerate);
	STAT(MOVEVARS_STOPSPEED, this) = Physics_ClientOption(this, "stopspeed", autocvar_sv_stopspeed);
	STAT(MOVEVARS_AIRACCELERATE, this) = Physics_ClientOption(this, "airaccelerate", autocvar_sv_airaccelerate);
	STAT(MOVEVARS_AIRSTOPACCELERATE, this) = Physics_ClientOption(this, "airstopaccelerate", autocvar_sv_airstopaccelerate);
	STAT(MOVEVARS_JUMPVELOCITY, this) = Physics_ClientOption(this, "jumpvelocity", autocvar_sv_jumpvelocity);
	STAT(MOVEVARS_TRACK_CANJUMP, this) = Physics_ClientOption(this, "track_canjump", autocvar_sv_track_canjump);
}
#endif

float IsMoveInDirection(vector mv, float ang) // key mix factor
{
	if (mv_x == 0 && mv_y == 0)
		return 0; // avoid division by zero
	ang -= RAD2DEG * atan2(mv_y, mv_x);
	ang = remainder(ang, 360) / 45;
	return ang > 1 ? 0 : ang < -1 ? 0 : 1 - fabs(ang);
}

float GeomLerp(float a, float _lerp, float b)
{
	return a == 0 ? (_lerp < 1 ? 0 : b)
		: b == 0 ? (_lerp > 0 ? 0 : a)
		: a * (fabs(b / a) ** _lerp);
}

void PM_ClientMovement_UpdateStatus(entity this)
{
#ifdef CSQC
	if(!IS_PLAYER(this))
		return;

	// set crouched
	bool do_crouch = PHYS_INPUT_BUTTON_CROUCH(this);
	for(int slot = 0; slot < MAX_WEAPONSLOTS; ++slot)
	{
		entity wep = viewmodels[slot];
		if(wep.hook && !wasfreed(wep.hook))
		{
			do_crouch = false;
			break; // don't bother checking the others
		}
	}
	if(this.waterlevel >= WATERLEVEL_SWIMMING)
		do_crouch = false;
	if(hud != HUD_NORMAL)
		do_crouch = false;
	if(STAT(FROZEN, this))
		do_crouch = false;

	if (do_crouch)
	{
		// wants to crouch, this always works
		if (!IS_DUCKED(this)) SET_DUCKED(this);
	}
	else
	{
		// wants to stand, if currently crouching we need to check for a low ceiling first
		if (IS_DUCKED(this))
		{
			tracebox(this.origin, STAT(PL_MIN, this), STAT(PL_MAX, this), this.origin, MOVE_NORMAL, this);
			if (!trace_startsolid) UNSET_DUCKED(this);
		}
	}

	if (IS_ONGROUND(this) || this.velocity.z <= 0 || PHYS_WATERJUMP_TIME(this) <= 0)
		PHYS_WATERJUMP_TIME(this) = 0;
#endif
}

void CPM_PM_Aircontrol(entity this, float dt, vector wishdir, float wishspeed)
{
	float movity = IsMoveInDirection(this.movement, 0);
	if(PHYS_AIRCONTROL_BACKWARDS(this))
		movity += IsMoveInDirection(this.movement, 180);

	float k = 32 * (2 * movity - 1);
	if (k <= 0)
		return;

	k *= bound(0, wishspeed / PHYS_MAXAIRSPEED(this), 1);

	float zspeed = this.velocity_z;
	this.velocity_z = 0;
	float xyspeed = vlen(this.velocity);
	this.velocity = normalize(this.velocity);

	float dot = this.velocity * wishdir;

	if (dot > 0) // we can't change direction while slowing down
	{
		k *= (dot ** PHYS_AIRCONTROL_POWER(this)) * dt;
		xyspeed = max(0, xyspeed - PHYS_AIRCONTROL_PENALTY(this) * sqrt(max(0, 1 - dot*dot)) * k/32);
		k *= PHYS_AIRCONTROL(this);
		this.velocity = normalize(this.velocity * xyspeed + wishdir * k);
	}

	this.velocity = this.velocity * xyspeed;
	this.velocity_z = zspeed;
}

float AdjustAirAccelQW(float accelqw, float factor)
{
	return copysign(bound(0.000001, 1 - (1 - fabs(accelqw)) * factor, 1), accelqw);
}

// example config for alternate speed clamping:
//   sv_airaccel_qw 0.8
//   sv_airaccel_sideways_friction 0
//   prvm_globalset server speedclamp_mode 1
//     (or 2)
void PM_Accelerate(entity this, float dt, vector wishdir, float wishspeed, float wishspeed0, float accel, float accelqw, float stretchfactor, float sidefric, float speedlimit)
{
	float speedclamp = stretchfactor > 0 ? stretchfactor
	: accelqw < 0 ? 1 // full clamping, no stretch
	: -1; // no clamping

	accelqw = fabs(accelqw);

	if (GAMEPLAYFIX_Q2AIRACCELERATE)
		wishspeed0 = wishspeed; // don't need to emulate this Q1 bug

	float vel_straight = this.velocity * wishdir;
	float vel_z = this.velocity_z;
	vector vel_xy = vec2(this.velocity);
	vector vel_perpend = vel_xy - vel_straight * wishdir;

	float step = accel * dt * wishspeed0;

	float vel_xy_current  = vlen(vel_xy);
	if (speedlimit)
		accelqw = AdjustAirAccelQW(accelqw, (speedlimit - bound(wishspeed, vel_xy_current, speedlimit)) / max(1, speedlimit - wishspeed));
	float vel_xy_forward =  vel_xy_current  + bound(0, wishspeed - vel_xy_current, step) * accelqw + step * (1 - accelqw);
	float vel_xy_backward = vel_xy_current  - bound(0, wishspeed + vel_xy_current, step) * accelqw - step * (1 - accelqw);
	vel_xy_backward = max(0, vel_xy_backward); // not that it REALLY occurs that this would cause wrong behaviour afterwards
	vel_straight =          vel_straight    + bound(0, wishspeed - vel_straight,   step) * accelqw + step * (1 - accelqw);

	if (sidefric < 0 && (vel_perpend*vel_perpend))
		// negative: only apply so much sideways friction to stay below the speed you could get by "braking"
	{
		float f = max(0, 1 + dt * wishspeed * sidefric);
		float themin = (vel_xy_backward * vel_xy_backward - vel_straight * vel_straight) / (vel_perpend * vel_perpend);
		// assume: themin > 1
		// vel_xy_backward*vel_xy_backward - vel_straight*vel_straight > vel_perpend*vel_perpend
		// vel_xy_backward*vel_xy_backward > vel_straight*vel_straight + vel_perpend*vel_perpend
		// vel_xy_backward*vel_xy_backward > vel_xy * vel_xy
		// obviously, this cannot be
		if (themin <= 0)
			vel_perpend *= f;
		else
		{
			themin = sqrt(themin);
			vel_perpend *= max(themin, f);
		}
	}
	else
		vel_perpend *= max(0, 1 - dt * wishspeed * sidefric);

	vel_xy = vel_straight * wishdir + vel_perpend;

	if (speedclamp >= 0)
	{
		float vel_xy_preclamp;
		vel_xy_preclamp = vlen(vel_xy);
		if (vel_xy_preclamp > 0) // prevent division by zero
		{
			vel_xy_current += (vel_xy_forward - vel_xy_current) * speedclamp;
			if (vel_xy_current < vel_xy_preclamp)
				vel_xy *= (vel_xy_current / vel_xy_preclamp);
		}
	}

	this.velocity = vel_xy + vel_z * '0 0 1';
}

void PM_AirAccelerate(entity this, float dt, vector wishdir, float wishspeed)
{
	if (wishspeed == 0)
		return;

	vector curvel = this.velocity;
	curvel_z = 0;
	float curspeed = vlen(curvel);

	if (wishspeed > curspeed * 1.01)
		wishspeed = min(wishspeed, curspeed + PHYS_WARSOWBUNNY_AIRFORWARDACCEL(this) * PHYS_MAXSPEED(this) * dt);
	else
	{
		float f = max(0, (PHYS_WARSOWBUNNY_TOPSPEED(this) - curspeed) / (PHYS_WARSOWBUNNY_TOPSPEED(this) - PHYS_MAXSPEED(this)));
		wishspeed = max(curspeed, PHYS_MAXSPEED(this)) + PHYS_WARSOWBUNNY_ACCEL(this) * f * PHYS_MAXSPEED(this) * dt;
	}
	vector wishvel = wishdir * wishspeed;
	vector acceldir = wishvel - curvel;
	float addspeed = vlen(acceldir);
	acceldir = normalize(acceldir);

	float accelspeed = min(addspeed, PHYS_WARSOWBUNNY_TURNACCEL(this) * PHYS_MAXSPEED(this) * dt);

	if (PHYS_WARSOWBUNNY_BACKTOSIDERATIO(this) < 1)
	{
		vector curdir = normalize(curvel);
		float dot = acceldir * curdir;
		if (dot < 0)
			acceldir -= (1 - PHYS_WARSOWBUNNY_BACKTOSIDERATIO(this)) * dot * curdir;
	}

	this.velocity += accelspeed * acceldir;
}


/*
=============
PlayerJump

When you press the jump key
returns true if handled
=============
*/
bool PlayerJump(entity this)
{
	if (PHYS_FROZEN(this))
		return true; // no jumping in freezetag when frozen

#ifdef SVQC
	if (this.player_blocked)
		return true; // no jumping while blocked
#endif

	bool doublejump = false;
	float mjumpheight = PHYS_JUMPVELOCITY(this);
	bool track_jump = PHYS_CL_TRACK_CANJUMP(this);

	if (MUTATOR_CALLHOOK(PlayerJump, this, mjumpheight, doublejump))
		return true;

	mjumpheight = M_ARGV(1, float);
	doublejump = M_ARGV(2, bool);

	if (this.waterlevel >= WATERLEVEL_SWIMMING)
	{
		if(this.viewloc)
		{
			doublejump = true;
			mjumpheight *= 0.7;
			track_jump = true;
		}
		else
		{
			this.velocity_z = PHYS_MAXSPEED(this) * 0.7;
			return true;
		}
	}

	if (!doublejump)
		if (!IS_ONGROUND(this) && !IS_ONSLICK(this))
			return IS_JUMP_HELD(this);

	if(PHYS_TRACK_CANJUMP(this))
		track_jump = true;

	if (track_jump)
		if (IS_JUMP_HELD(this))
			return true;

	// sv_jumpspeedcap_min/sv_jumpspeedcap_max act as baseline
	// velocity bounds.  Final velocity is bound between (jumpheight *
	// min + jumpheight) and (jumpheight * max + jumpheight);

	if(PHYS_JUMPSPEEDCAP_MIN != "")
	{
		float minjumpspeed = mjumpheight * stof(PHYS_JUMPSPEEDCAP_MIN);

		if (this.velocity_z < minjumpspeed)
			mjumpheight += minjumpspeed - this.velocity_z;
	}

	if(PHYS_JUMPSPEEDCAP_MAX != "")
	{
		// don't do jump speedcaps on ramps to preserve old xonotic ramjump style
		tracebox(this.origin + '0 0 0.01', this.mins, this.maxs, this.origin - '0 0 0.01', MOVE_NORMAL, this);

		if (!(trace_fraction < 1 && trace_plane_normal_z < 0.98 && PHYS_JUMPSPEEDCAP_DISABLE_ONRAMPS(this)))
		{
			float maxjumpspeed = mjumpheight * stof(PHYS_JUMPSPEEDCAP_MAX);

			if (this.velocity_z > maxjumpspeed)
				mjumpheight -= this.velocity_z - maxjumpspeed;
		}
	}

	if (!WAS_ONGROUND(this) && !WAS_ONSLICK(this))
	{
#ifdef SVQC
		if(autocvar_speedmeter)
			LOG_TRACE("landing velocity: ", vtos(this.velocity), " (abs: ", ftos(vlen(this.velocity)), ")");
#endif
		if(this.lastground < time - 0.3)
		{
			float f = (1 - PHYS_FRICTION_ONLAND(this));
			this.velocity_x *= f;
			this.velocity_y *= f;
		}
#ifdef SVQC
		if(this.jumppadcount > 1)
			LOG_TRACE(ftos(this.jumppadcount), "x jumppad combo");
		this.jumppadcount = 0;
#endif
	}

	this.velocity_z += mjumpheight;

	UNSET_ONGROUND(this);
	UNSET_ONSLICK(this);
	SET_JUMP_HELD(this);

#ifdef SVQC

	this.oldvelocity_z = this.velocity_z;

	animdecide_setaction(this, ANIMACTION_JUMP, true);

	if (autocvar_g_jump_grunt)
		PlayerSound(this, playersound_jump, CH_PLAYER, VOL_BASE, VOICETYPE_PLAYERSOUND);
#endif
	return true;
}

void CheckWaterJump(entity this)
{
// check for a jump-out-of-water
	makevectors(this.v_angle);
	vector start = this.origin;
	start_z += 8;
	v_forward_z = 0;
	normalize(v_forward);
	vector end = start + v_forward*24;
	traceline (start, end, true, this);
	if (trace_fraction < 1)
	{	// solid at waist
		start_z = start_z + this.maxs_z - 8;
		end = start + v_forward*24;
		this.movedir = trace_plane_normal * -50;
		traceline(start, end, true, this);
		if (trace_fraction == 1)
		{	// open at eye level
			this.velocity_z = 225;
			this.flags |= FL_WATERJUMP;
			SET_JUMP_HELD(this);
		#ifdef SVQC
			PHYS_TELEPORT_TIME(this) = time + 2;	// safety net
		#elif defined(CSQC)
			PHYS_WATERJUMP_TIME(this) = 2;
		#endif
		}
	}
}


#ifdef SVQC
	#define JETPACK_JUMP(s)	s.cvar_cl_jetpack_jump
#elif defined(CSQC)
	float autocvar_cl_jetpack_jump;
	#define JETPACK_JUMP(s)	autocvar_cl_jetpack_jump
#endif
.float jetpack_stopped;
void CheckPlayerJump(entity this)
{
#ifdef SVQC
	bool was_flying = boolean(ITEMS_STAT(this) & IT_USING_JETPACK);
#endif
	if (JETPACK_JUMP(this) < 2)
		ITEMS_STAT(this) &= ~IT_USING_JETPACK;

	if(PHYS_INPUT_BUTTON_JUMP(this) || PHYS_INPUT_BUTTON_JETPACK(this))
	{
		bool playerjump = PlayerJump(this); // required

		bool air_jump = !playerjump || M_ARGV(2, bool);
		bool activate = JETPACK_JUMP(this) && air_jump && PHYS_INPUT_BUTTON_JUMP(this) || PHYS_INPUT_BUTTON_JETPACK(this);
		bool has_fuel = !PHYS_JETPACK_FUEL(this) || PHYS_AMMO_FUEL(this) || (ITEMS_STAT(this) & IT_UNLIMITED_WEAPON_AMMO);

		if (!(ITEMS_STAT(this) & ITEM_Jetpack.m_itemid)) { }
		else if (this.jetpack_stopped) { }
		else if (!has_fuel)
		{
#ifdef SVQC
			if (was_flying) // TODO: ran out of fuel message
				Send_Notification(NOTIF_ONE, this, MSG_INFO, INFO_JETPACK_NOFUEL);
			else if (activate)
				Send_Notification(NOTIF_ONE, this, MSG_INFO, INFO_JETPACK_NOFUEL);
#endif
			this.jetpack_stopped = true;
			ITEMS_STAT(this) &= ~IT_USING_JETPACK;
		}
		else if (activate && !PHYS_FROZEN(this))
			ITEMS_STAT(this) |= IT_USING_JETPACK;
	}
	else
	{
		this.jetpack_stopped = false;
		ITEMS_STAT(this) &= ~IT_USING_JETPACK;
	}
	if (!PHYS_INPUT_BUTTON_JUMP(this))
		UNSET_JUMP_HELD(this);

	if (this.waterlevel == WATERLEVEL_SWIMMING)
		CheckWaterJump(this);
}

float racecar_angle(float forward, float down)
{
	if (forward < 0)
	{
		forward = -forward;
		down = -down;
	}

	float ret = vectoyaw('0 1 0' * down + '1 0 0' * forward);

	float angle_mult = forward / (800 + forward);

	if (ret > 180)
		return ret * angle_mult + 360 * (1 - angle_mult);
	else
		return ret * angle_mult;
}

#ifdef SVQC
string specialcommand = "xwxwxsxsxaxdxaxdx1x ";
.float specialcommand_pos;
void SpecialCommand(entity this)
{
	if (!CheatImpulse(this, CHIMPULSE_GIVE_ALL.impulse))
		LOG_INFO("A hollow voice says \"Plugh\".\n");
}
#endif

bool PM_check_specialcommand(entity this, int buttons)
{
#ifdef SVQC
	string c;
	if (!buttons)
		c = "x";
	else if (buttons == 1)
		c = "1";
	else if (buttons == 2)
		c = " ";
	else if (buttons == 128)
		c = "s";
	else if (buttons == 256)
		c = "w";
	else if (buttons == 512)
		c = "a";
	else if (buttons == 1024)
		c = "d";
	else
		c = "?";

	if (c == substring(specialcommand, this.specialcommand_pos, 1))
	{
		this.specialcommand_pos += 1;
		if (this.specialcommand_pos >= strlen(specialcommand))
		{
			this.specialcommand_pos = 0;
			SpecialCommand(this);
			return true;
		}
	}
	else if (this.specialcommand_pos && (c != substring(specialcommand, this.specialcommand_pos - 1, 1)))
		this.specialcommand_pos = 0;
#endif
	return false;
}

void PM_check_nickspam(entity this)
{
#ifdef SVQC
	if (time >= this.nickspamtime)
		return;
	if (this.nickspamcount >= autocvar_g_nick_flood_penalty_yellow)
	{
		// slight annoyance for nick change scripts
		this.movement = -1 * this.movement;
		PHYS_INPUT_BUTTON_ATCK(this) = PHYS_INPUT_BUTTON_JUMP(this) = PHYS_INPUT_BUTTON_ATCK2(this) = PHYS_INPUT_BUTTON_ZOOM(this) = PHYS_INPUT_BUTTON_CROUCH(this) = PHYS_INPUT_BUTTON_HOOK(this) = PHYS_INPUT_BUTTON_USE(this) = false;

		if (this.nickspamcount >= autocvar_g_nick_flood_penalty_red) // if you are persistent and the slight annoyance above does not stop you, I'll show you!
		{
			this.v_angle_x = random() * 360;
			this.v_angle_y = random() * 360;
			// at least I'm not forcing retardedview by also assigning to angles_z
			this.fixangle = true;
		}
	}
#endif
}

void PM_check_punch(entity this, float dt)
{
#ifdef SVQC
	if (this.punchangle != '0 0 0')
	{
		float f = vlen(this.punchangle) - 10 * dt;
		if (f > 0)
			this.punchangle = normalize(this.punchangle) * f;
		else
			this.punchangle = '0 0 0';
	}

	if (this.punchvector != '0 0 0')
	{
		float f = vlen(this.punchvector) - 30 * dt;
		if (f > 0)
			this.punchvector = normalize(this.punchvector) * f;
		else
			this.punchvector = '0 0 0';
	}
#endif
}

// predict frozen movement, as frozen players CAN move in some cases
void PM_check_frozen(entity this)
{
	if (!PHYS_FROZEN(this))
		return;
	if (PHYS_DODGING_FROZEN(this)
#ifdef SVQC
	&& IS_REAL_CLIENT(this)
#endif
	)
	{
		this.movement_x = bound(-5, this.movement.x, 5);
		this.movement_y = bound(-5, this.movement.y, 5);
		this.movement_z = bound(-5, this.movement.z, 5);
	}
	else
		this.movement = '0 0 0';

	vector midpoint = ((this.absmin + this.absmax) * 0.5);
	if (pointcontents(midpoint) == CONTENT_WATER)
	{
		this.velocity = this.velocity * 0.5;

		if (pointcontents(midpoint + '0 0 16') == CONTENT_WATER)
			this.velocity_z = 200;
	}
}

void PM_check_hitground(entity this)
{
#ifdef SVQC
	if (!this.wasFlying) return;
    this.wasFlying = false;
    if (this.waterlevel >= WATERLEVEL_SWIMMING) return;
    if (time < this.ladder_time) return;
    for(int slot = 0; slot < MAX_WEAPONSLOTS; ++slot)
    {
    	.entity weaponentity = weaponentities[slot];
    	if(this.(weaponentity).hook)
    		return;
    }
    this.nextstep = time + 0.3 + random() * 0.1;
    trace_dphitq3surfaceflags = 0;
    tracebox(this.origin, this.mins, this.maxs, this.origin - '0 0 1', MOVE_NOMONSTERS, this);
    if (trace_dphitq3surfaceflags & Q3SURFACEFLAG_NOSTEPS) return;
    entity gs = (trace_dphitq3surfaceflags & Q3SURFACEFLAG_METALSTEPS)
    	? GS_FALL_METAL
    	: GS_FALL;
    float vol = ((IS_DUCKED(this)) ? VOL_MUFFLED : VOL_BASE);
    GlobalSound(this, gs, CH_PLAYER, vol, VOICETYPE_PLAYERSOUND);
#endif
}

void PM_Footsteps(entity this)
{
#ifdef SVQC
	if (!g_footsteps) return;
	if (IS_DUCKED(this)) return;
	if (time >= this.lastground + 0.2) return;
	if (vdist(this.velocity, <=, autocvar_sv_maxspeed * 0.6)) return;
	if ((time > this.nextstep) || (time < (this.nextstep - 10.0)))
	{
		this.nextstep = time + 0.3 + random() * 0.1;
		trace_dphitq3surfaceflags = 0;
		tracebox(this.origin, this.mins, this.maxs, this.origin - '0 0 1', MOVE_NOMONSTERS, this);
		if (trace_dphitq3surfaceflags & Q3SURFACEFLAG_NOSTEPS) return;
		entity gs = (trace_dphitq3surfaceflags & Q3SURFACEFLAG_METALSTEPS)
			? GS_STEP_METAL
			: GS_STEP;
		GlobalSound(this, gs, CH_PLAYER, VOL_BASE, VOICETYPE_PLAYERSOUND);
	}
#endif
}

void PM_check_slick(entity this)
{
	if(!IS_ONGROUND(this))
		return;

	if(!PHYS_SLICK_APPLYGRAVITY(this))
		return;

	tracebox(this.origin, this.mins, this.maxs, this.origin - '0 0 1', MOVE_NOMONSTERS, this);
	if (trace_dphitq3surfaceflags & Q3SURFACEFLAG_SLICK)
	{
		UNSET_ONGROUND(this);
		SET_ONSLICK(this);
	}
	else
		UNSET_ONSLICK(this);
}

void PM_check_blocked(entity this)
{
#ifdef SVQC
	if (!this.player_blocked)
		return;
	this.movement = '0 0 0';
	this.disableclientprediction = 1;
#endif
}

void PM_jetpack(entity this, float maxspd_mod, float dt)
{
	//makevectors(this.v_angle.y * '0 1 0');
	makevectors(this.v_angle);
	vector wishvel = v_forward * this.movement_x
					+ v_right * this.movement_y;
	// add remaining speed as Z component
	float maxairspd = PHYS_MAXAIRSPEED(this) * max(1, maxspd_mod);
	// fix speedhacks :P
	wishvel = normalize(wishvel) * min(1, vlen(wishvel) / maxairspd);
	// add the unused velocity as up component
	wishvel_z = 0;

	// if (PHYS_INPUT_BUTTON_JUMP(this))
		wishvel_z = sqrt(max(0, 1 - wishvel * wishvel));

	// it is now normalized, so...
	float a_side = PHYS_JETPACK_ACCEL_SIDE(this);
	float a_up = PHYS_JETPACK_ACCEL_UP(this);
	float a_add = PHYS_JETPACK_ANTIGRAVITY(this) * PHYS_GRAVITY(this);

	if(PHYS_JETPACK_REVERSE_THRUST(this) && PHYS_INPUT_BUTTON_CROUCH(self)) { a_up = PHYS_JETPACK_REVERSE_THRUST(this); }

	wishvel_x *= a_side;
	wishvel_y *= a_side;
	wishvel_z *= a_up;
	wishvel_z += a_add;

	if(PHYS_JETPACK_REVERSE_THRUST(this) && PHYS_INPUT_BUTTON_CROUCH(self)) { wishvel_z *= -1; }

	float best = 0;
	//////////////////////////////////////////////////////////////////////////////////////
	// finding the maximum over all vectors of above form
	// with wishvel having an absolute value of 1
	//////////////////////////////////////////////////////////////////////////////////////
	// we're finding the maximum over
	//   f(a_side, a_up, a_add, z) := a_side * (1 - z^2) + (a_add + a_up * z)^2;
	// for z in the range from -1 to 1
	//////////////////////////////////////////////////////////////////////////////////////
	// maximum is EITHER attained at the single extreme point:
	float a_diff = a_side * a_side - a_up * a_up;
	float f;
	if (a_diff != 0)
	{
		f = a_add * a_up / a_diff; // this is the zero of diff(f(a_side, a_up, a_add, z), z)
		if (f > -1 && f < 1) // can it be attained?
		{
			best = (a_diff + a_add * a_add) * (a_diff + a_up * a_up) / a_diff;
			//print("middle\n");
		}
	}
	// OR attained at z = 1:
	f = (a_up + a_add) * (a_up + a_add);
	if (f > best)
	{
		best = f;
		//print("top\n");
	}
	// OR attained at z = -1:
	f = (a_up - a_add) * (a_up - a_add);
	if (f > best)
	{
		best = f;
		//print("bottom\n");
	}
	best = sqrt(best);
	//////////////////////////////////////////////////////////////////////////////////////

	//print("best possible acceleration: ", ftos(best), "\n");

	float fxy, fz;
	fxy = bound(0, 1 - (this.velocity * normalize(wishvel_x * '1 0 0' + wishvel_y * '0 1 0')) / PHYS_JETPACK_MAXSPEED_SIDE(this), 1);
	if (wishvel_z - PHYS_GRAVITY(this) > 0)
		fz = bound(0, 1 - this.velocity_z / PHYS_JETPACK_MAXSPEED_UP(this), 1);
	else
		fz = bound(0, 1 + this.velocity_z / PHYS_JETPACK_MAXSPEED_UP(this), 1);

	float fvel;
	fvel = vlen(wishvel);
	wishvel_x *= fxy;
	wishvel_y *= fxy;
	wishvel_z = (wishvel_z - PHYS_GRAVITY(this)) * fz + PHYS_GRAVITY(this);

	fvel = min(1, vlen(wishvel) / best);
	if (PHYS_JETPACK_FUEL(this) && !(ITEMS_STAT(this) & IT_UNLIMITED_WEAPON_AMMO))
		f = min(1, PHYS_AMMO_FUEL(this) / (PHYS_JETPACK_FUEL(this) * dt * fvel));
	else
		f = 1;

	//print("this acceleration: ", ftos(vlen(wishvel) * f), "\n");

	if (f > 0 && wishvel != '0 0 0')
	{
		this.velocity = this.velocity + wishvel * f * dt;
		UNSET_ONGROUND(this);

#ifdef SVQC
		if (!(ITEMS_STAT(this) & IT_UNLIMITED_WEAPON_AMMO))
			this.ammo_fuel -= PHYS_JETPACK_FUEL(this) * dt * fvel * f;

		ITEMS_STAT(this) |= IT_USING_JETPACK;

		// jetpack also inhibits health regeneration, but only for 1 second
		this.pauseregen_finished = max(this.pauseregen_finished, time + autocvar_g_balance_pause_fuel_regen);
#endif
	}
}

// used for calculating airshots
bool IsFlying(entity this)
{
	if(IS_ONGROUND(this))
		return false;
	if(this.waterlevel >= WATERLEVEL_SWIMMING)
		return false;
	traceline(this.origin, this.origin - '0 0 48', MOVE_NORMAL, this);
	if(trace_fraction < 1)
		return false;
	return true;
}


void sys_phys_update(entity this, float dt);
#if defined(SVQC)
void SV_PlayerPhysics(entity this)
#elif defined(CSQC)
void CSQC_ClientMovement_PlayerMove_Frame(entity this)
#endif
{
	sys_phys_update(this, PHYS_INPUT_TIMELENGTH);

#ifdef SVQC
	this.pm_frametime = frametime;
#elif defined(CSQC)
	if((ITEMS_STAT(this) & IT_USING_JETPACK) && !IS_DEAD(this) && !intermission)
		this.csqcmodel_modelflags |= MF_ROCKET;
	else
		this.csqcmodel_modelflags &= ~MF_ROCKET;
#endif
}