-- QuakeViewroll: adds Quake-style viewroll to Sonic Robo Blast 2
-- Copyright (C) 2024 Biff
-- 
-- This program is free software; you can redistribute it and/or
-- modify it under the terms of the GNU General Public License
-- as published by the Free Software Foundation; either version 2
-- of the License, or (at your option) any later version.
-- 
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.
-- 
-- You should have received a copy of the GNU General Public License
-- along with this program; if not, write to the Free Software
-- Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

local function dotProduct(x1,y1,x2,y2)
	return FixedMul(x1,x2)+FixedMul(y1,y2)
end

local function angToVec2(ang)
	return cos(ang), sin(ang)
end

local function getRightAngle(mobj, camera)
	if camera.chase == false then
		-- camera.angle returns 0 here, use mobj's angle
		return mobj.angle+ANGLE_90
	else
		return camera.angle+ANGLE_90
	end
end

local function viewRoll()
	if displayplayer == nil then return end
	if displayplayer.mo == nil then return end
	if (maptol & TOL_NIGHTS) then return end -- let them handle it
	local mo = displayplayer.mo
	local ang = 0
	local angx, angy = 0, 0
	local momx, momy = mo.momx, mo.momy
	ang = getRightAngle(mo, camera)
	angx, angy = angToVec2(ang)
	-- V_CalcRoll, Quake/WinQuake/view.c:81
	local side = 0
	local sign = 0
	local value = 0
	local cl_rollspeed = CV_FindVar("cl_rollspeed")
	local cl_rollangle = CV_FindVar("cl_rollangle")
	side = dotProduct(momx, momy, angx, angy)
	sign = side < 0 and -1 or 1
	side = abs($)
	value = cl_rollangle.value
	if side < cl_rollspeed.value then
		-- CV_FLOAT convars return a multiple of FRACUNIT
		side = FixedDiv(FixedMul(side , value) , cl_rollspeed.value)
	else
		side = value
	end
	-- Doing viewrollangle = $ - side*sign accumulates viewroll. We don't want that.
	-- SV_ClientThink, Quake/WinQuake/sv_user.c:407
	displayplayer.viewrollangle = FixedMul(InvAngle(FixedAngle(side*sign)), 4*FRACUNIT)
	local v_kicktime = CV_FindVar("v_kicktime")
	if displayplayer.v_dmg_time ~= nil and displayplayer.v_dmg_time > 0 then
		-- Why does C prioritize division here?
		local kick = FixedMul(FixedDiv(displayplayer.v_dmg_time, v_kicktime.value), displayplayer.v_dmg_roll)
		displayplayer.viewrollangle = $ + InvAngle(FixedAngle(kick))
		displayplayer.v_dmg_time = $ - (FRACUNIT/35); -- one tic
	end
	if displayplayer.playerstate == PST_DEAD and CV_FindVar("cl_deathtilt").value ~= 0 then
		-- Tilt the camera when you die, just like in Quake
		displayplayer.viewrollangle = FixedAngle(80*FRACUNIT)
	end
end

local function kickRoll(target, inflictor)--, source, damage, damagetype)
	if displayplayer == nil then return end
	if displayplayer.mo == nil then return end
	local mo = displayplayer.mo
	if target == displayplayer.mo then
		-- V_ParseDamage, Quake/WinQuake/view.c:367
		local fromX = displayplayer.mo.x
		local fromY = displayplayer.mo.y
		if inflictor ~= nil then
			fromX = inflictor.x
			fromY = inflictor.y
		end
		fromX = fromX - displayplayer.mo.x
		fromY = fromY - displayplayer.mo.x
		-- Normalize the Crocodile
		local length = FixedHypot(fromX, fromY)
		fromX = FixedDiv($, length)
		fromY = FixedDiv($, length)
		local v_kickroll = CV_FindVar("v_kickroll")
		local v_kicktime = CV_FindVar("v_kicktime")
		local ang = getRightAngle(mo, camera)
		local angX, angY = angToVec2(ang)
		local side = dotProduct(fromX, fromY, angX, angY)
		displayplayer.v_dmg_roll = FixedMul(10*FRACUNIT, FixedMul(side, v_kickroll.value))
		displayplayer.v_dmg_time = v_kicktime.value
	end
end

local convars = {}
local initialized = false

local function writeConfig()
	if not initialized then return end
	local file = io.openlocal("client/qvr_autorun.cfg", "w")
	if file == nil then return end
	for _,v in ipairs(convars) do
		file:write(string.format("%s\t%s\n", v.name, v.string))
	end
	file:close()
end

local function readConfig()
	local file = io.openlocal("client/qvr_autorun.cfg", "r")
	if file == nil then return end
	for c in file:lines() do
		local f = {}
		for k in c:gmatch("[^;,%s]+") do
			table.insert(f, k)
		end
		if #f >= 2 then
			local convar = CV_FindVar(f[1])
			if convar ~= nil then CV_StealthSet(convar, f[2]) end -- don't write back to the cfg
		end
	end
	file:close()
end

convars[#convars+1] = CV_RegisterVar({
	name = "cl_rollspeed",
	defaultvalue = "36", -- Quake cl_rollspeed. 200 is Quake's run speed, 36 is SRB2's (default) run speed
	flags = CV_CALL|CV_FLOAT,
	PossibleValue = nil,
	func = writeConfig
})
convars[#convars+1] = CV_RegisterVar({
	name = "cl_rollangle", -- Quake cl_rollangle. Internally multiplied by 4
	defaultvalue = "2.0",
	flags = CV_CALL|CV_FLOAT,
	PossibleValue = nil,
	func = writeConfig
})
convars[#convars+1] = CV_RegisterVar({ -- Quake v_kickroll. Internally multiplied by 10
	name = "v_kickroll",
	defaultvalue = "0.6",
	flags = CV_CALL|CV_FLOAT,
	PossibleValue = nil,
	func = writeConfig
})
convars[#convars+1] = CV_RegisterVar({ -- Quake v_kicktime, in seconds(?)
	name = "v_kicktime",
	defaultvalue = "0.5",
	flags = CV_CALL|CV_FLOAT,
	PossibleValue = nil,
	func = writeConfig
})
convars[#convars+1] = CV_RegisterVar({ -- Tilt the camera when you die, like in Quake
	name = "cl_deathtilt",
	defaultvalue = "Off",
	flags = CV_CALL,
	PossibleValue = CV_OnOff,
	func = writeConfig
})

readConfig()

initialized = true -- default value being set calls func?

addHook("ThinkFrame", viewRoll)
addHook("MobjDamage", kickRoll)
addHook("PlayerSpawn", function(player)
	-- avoid debug flood
	if player == displayplayer then displayplayer.v_dmg_roll = 0; displayplayer.v_dmg_time = 0 end
end)