-- title:   kistaro-compositor
-- author:  Kistaro Windrider (kistaro@gmail.com)
-- desc:    Rendering compositor library. Includes Pico-8 camera features.
-- site:    https://dragon.style/@kistaro
-- license: MIT License
-- version: 0.1
-- script:  lua


function BOOT()
end

function TIC()
end

--stdlib--

-- generate standard "overlay"
-- constructor for type tt.
-- if more is defined, generated
-- new calls more(ret) after ret is
-- definitely not nil, before calling
-- setmetatable. Use to initialize
-- mutable items.
function MkNew(tt, more)
	local mt = {__index=tt}
	-- check "more" only once ever
	if more then
	 tt.new = function(ret)
		 ret = ret or {}
			more(ret)
			setmetatable(ret, mt)
			return ret
		end
	else
	 tt.new = function(ret)
	 	ret = ret or {}
	 	setmetatable(ret, mt)
	  return ret
		end
	end
end

--Window compositor--

CamCtl = {
 XOff = 0,
 YOff = 0,
 XAbsClip = 0,
 YAbsClip = 0,
 W = 240,
 H = 136,
 OriginStack = {},
 ClipStack = {},
}

-- Overwrite current camera origin.
-- (0, 0) is now this pixel coordinate.
function CamCtl:SetAbsOrigin(x, y)
 self.XOff, self.YOff = x, y
end

-- Push current camera origin onto
-- the history stack and set the
-- new origin.
function CamCtl:PushAbsOrigin(x, y)
 table.insert(self.OriginStack, {self.XOff, self.YOff})
 self.XOff, self.YOff = x, y
end

function CamCtl:SetRelOrigin(x, y)
 self.XOff = self.XOff + x
 self.YOff = self.Yoff + y
end

function CamCtl:PushRelOrigin(x, y)
 table.insert(self.OriginStack, {self.XOff, self.YOff})
 self.XOff = self.XOff + x
 self.YOff = self.YOff + Y
end

function CamCtl:SetAbsCam(x, y)
 self.XOff, self.YOff = -x, -y
end

function CamCtl:PushAbsCam(x, y)
 table.insert(self.OriginStack, {self.XOff, self.YOff})
 self.XOff, self.YOff = -x, -y
end

function CamCtl:SetRelCam(x, y)
 self.XOff = self.XOff - x
 self.YOff = self.YOff - y
end

function CamCtl:PushRelCam(x, y)
 table.insert(self.OriginStack, {self.XOff, self.YOff})
 self.XOff = self.XOff - x
 self.YOff = self.YOff - y
end 

function CamCtl:PopOrigin()
 if #self.OriginStack == 0 then
  self.XOff, self.YOff = 0, 0
  return
 end
 self.XOff, self.YOff = unpack(table.Remove(self.OriginStack))
end
CamCtl.PopCam = CamCtl.PopOrigin

function CamCtl:SetNewClip(x, y, w, h)
 if x then
  self.XAbsClip = self.XOff + x
  self.YAbsClip = self.YOff + y
  self.W, self.H = w, h
  clip(self.XAbsClip, self.YAbsClip, self.W, self.H)
  return
 end
 self.XAbsClip, self.YAbsClip, self.W, self.H = 0,0,240,136
 clip()
end

function CamCtl:PushNewClip(x, y, w, h)
 table.insert(self.ClipStack, {self.XAbsClip, self.YAbsClip, self.W, self.H})
 self:SetNewClip(x, y, w, h)
end

function CamCtl:SetReClip(x,y,w,h)
 if not x then
  return
 end
 
 x = x + self.XOff
 local x2 = math.min(x + w, self.XAbsClip + self.W)
 self.XAbsClip = math.max(x, self.XAbsClip)
 self.W = max(0, x2 - self.XAbsClip)
 
 y = y + self.YOff
 local y2 = math.min(y+h, self.YAbsClip + self.H)
 self.YAbsClip = math.max(y, self.YAbsClip)
 self.H = max(0, y2 - self.YAbsClip)

 clip(self.XAbsClip, self.YAbsClip, self.W, self.H)
end

function CamCtl:PushReClip(x,y,w,h)
 table.insert(self.ClipStack, {self.XAbsClip, self.YAbsClip, self.W, self.H})
 self.SetReClip(x,y,w,h)
end

function CamCtl:PopClip()
 if #self.ClipStack == 0 then
  self.XAbsClip, self.YAbsClip, self.W, self.H = 0,0,240,136
  clip()
  return
 end
 local x,y,w,h = unpack(table.remove(self.ClipStack)))
 self.XAbsClip, self.YAbsClip, self.W, self.H = x,y,w,h
 clip(x,y,w,h)
end
-- Install
-- (swizzle all drawing functions!)

function CamCtl:Install()
 local adjust_leading_2 = {
  "circ", "circb",
  "elli", "ellib",
  "pix",
  "rect", "rectb",
 }
 for _, fn in ipairs(adjust_leading_2) do
  local f_orig = _G[fn]
  _G[fn] = function(x, y, ...)
   return f_orig(x + self.XOff, y + self.YOff, ...)
  end
 end
 
 local keep_first_adjust_2_opt = {
  "spr", "font", "print"
 }
 for _, fn in ipairs(keep_first_adjust_2_opt) do
  local f_orig = _G[fn]
  _G[fn] = function(v, x, y, ...)
   if x then
    x = x + self.XOff
   end
   if y then
    y = y + self.YOff
   end
   return f_orig(v, x, y, ...)
  end
 end

 local tri_family = {"tri", "trib", "textri"}
 
 for _, fn in ipairs(tri_family) do
  local f_orig = _G[fn]
  _G[fn] = function(x1, y1, x2, y2, x3, y3, ...)
   return f_orig(
    x1 + self.XOff, y1 + self.YOff,
    x2 + self.XOff, y2 + self.YOff,
    x3 + self.XOff, y3 + self.YOff,
    ...
   )
  end
 end
 
 local map_orig = map
 map = function(mx, my, w, h, sx, sy, ...)
  XXX(kistaro): implement!
  -- if called with no args, calculate new map
  -- coordinates, clipping at 0, to respect
  -- camera movement! this will require full tile
  -- movement to be reflected in mx/my, w and h to
  -- stay 30 x 17 unless they go to 31 x 18 for
  -- partial tiles at edges, and sx and sy to become
  -- offsets. If sx and sy are provided, do the
  -- obvious thing instead, which is much easier.
 end
 
 local line_orig = line
 line = function(x0, y0, x1, y1, color)
  return line_orig(
   x0 + self.XOff, y0 + self.YOff,
   x1 + self.XOff, y1 + self.YOff,
   color
  )
 end
end
-- <SPRITES>
-- 000:0222220021111110212121102122211021121110211111100111110000000000
-- 001:0bbbbb00b9999980b999b980b99bb980b9bbb980b99999800888880000000000
-- 002:0555550056666670565566705655567056655670566666700777770000000000
-- 003:0444440043333320433433204344432043434320433333200222220000000000
-- 004:0ddddd00deeeeef0dededef0deedeef0dededef0deeeeef00fffff0000000000
-- </SPRITES>

-- <WAVES>
-- 000:00000000ffffffff00000000ffffffff
-- 001:0123456789abcdeffedcba9876543210
-- 002:0123456789abcdef0123456789abcdef
-- </WAVES>

-- <SFX>
-- 000:000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000304000000000
-- </SFX>

-- <TRACKS>
-- 000:100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- </TRACKS>

-- <PALETTE>
-- 000:1a1c2c5d275db13e53ef7d57ffcd75a7f07038b76425717929366f3b5dc941a6f673eff7f4f4f4be69ce61309940205d
-- </PALETTE>