-- config
--------------------------------

--sfx
snd=
{

}

--music tracks
mus=
{

}

--math
--------------------------------

--point to box intersection.
function intersects_point_box(px,py,x,y,w,h)
	if flr(px)>=flr(x) and flr(px)<flr(x+w) and
				flr(py)>=flr(y) and flr(py)<flr(y+h) then
		return true
	else
		return false
	end
end

--box to box intersection
function intersects_box_box(
	x1,y1,
	w1,h1,
	x2,y2,
	w2,h2)

	local xd=x1-x2
	local xs=w1*0.5+w2*0.5
	if abs(xd)>=xs then return false end

	local yd=y1-y2
	local ys=h1*0.5+h2*0.5
	if abs(yd)>=ys then return false end

	return true
end

--check if pushing into side tile and resolve.
--requires self.dx,self.x,self.y, and 
--assumes tile flag 0 == solid
--assumes sprite size of 8x8
function collide_side(self)

	local offset=self.w/3
	for i=-(self.w/3),(self.w/3),2 do
	--if self.dx>0 then
		if fget(mget((self.x+(offset))/8,(self.y+i)/8),0) then
			self.dx=0
			self.x=(flr(((self.x+(offset))/8))*8)-(offset)
			return true
		end
	--elseif self.dx<0 then
		if fget(mget((self.x-(offset))/8,(self.y+i)/8),0) then
			self.dx=0
			self.x=(flr((self.x-(offset))/8)*8)+8+(offset)
			return true
		end
--	end
	end
	--didn't hit a solid tile.
	return false
end

--check if pushing into floor tile and resolve.
--requires self.dx,self.x,self.y,self.grounded,self.airtime and 
--assumes tile flag 0 or 1 == solid
function collide_floor(self)
	--only check for ground when falling.
	if self.dy<0 then
		return false
	end
	local landed=false
	--check for collision at multiple points along the bottom
	--of the sprite: left, center, and right.
	for i=-(self.w/3),(self.w/3),2 do
		local tile=mget((self.x+i)/8,(self.y+(self.h/2))/8)
		if fget(tile,0) or (fget(tile,1) and self.dy>=0) then
			self.dy=0
			self.y=(flr((self.y+(self.h/2))/8)*8)-(self.h/2)
			self.grounded=true
			self.airtime=0
			landed=true
		end
	end
	return landed
end

--check if pushing into roof tile and resolve.
--requires self.dy,self.x,self.y, and 
--assumes tile flag 0 == solid
function collide_roof(self)
	--check for collision at multiple points along the top
	--of the sprite: left, center, and right.
	for i=-(self.w/3),(self.w/3),2 do
		if fget(mget((self.x+i)/8,(self.y-(self.h/2))/8),0) then
			self.dy=0
			self.y=flr((self.y-(self.h/2))/8)*8+8+(self.h/2)
			self.jump_hold_time=0
		end
	end
end

--make 2d vector
function m_vec(x,y)
	local v=
	{
		x=x,
		y=y,

  --get the length of the vector
		get_length=function(self)
			return sqrt(self.x^2+self.y^2)
		end,

  --get the normal of the vector
		get_norm=function(self)
			local l = self:get_length()
			return m_vec(self.x / l, self.y / l),l;
		end,
	}
	return v
end

--square root.
function sqr(a) return a*a end

--round to the nearest whole number.
function round(a) return flr(a+0.5) end

--utils
--------------------------------

--print string with outline.
function printo(str,startx,
															 starty,col,
															 col_bg)
	print(str,startx+1,starty,col_bg)
	print(str,startx-1,starty,col_bg)
	print(str,startx,starty+1,col_bg)
	print(str,startx,starty-1,col_bg)
	print(str,startx+1,starty-1,col_bg)
	print(str,startx-1,starty-1,col_bg)
	print(str,startx-1,starty+1,col_bg)
	print(str,startx+1,starty+1,col_bg)
	print(str,startx,starty,col)
end

--print string centered with 
--outline.
function printc(
	str,x,y,
	col,col_bg,
	special_chars)

	local len=(#str*4)+(special_chars*3)
	local startx=x-(len/2)
	local starty=y-2
	printo(str,startx,starty,col,col_bg)
end

--objects
--------------------------------

--make the player
function m_player(x,y)

	--todo: refactor with m_vec.
	local p=
	{
		x=x,
		y=y,

		dx=0,
		dy=0,

		w=8,
		h=8,

		max_dx=1,--max x speed
		max_dy=2,--max y speed

		jump_speed=-1.75,--jump veloclity
		acc=0.05,--acceleration
		dcc=0.8,--decceleration
		air_dcc=1,--air decceleration
		grav=0.15,

		--helper for more complex
		--button press tracking.
		--todo: generalize button index.
		jump_button=
		{
			update=function(self)
				--start with assumption
				--that not a new press.
				self.is_pressed=false
				if btn(2) then
					if not self.is_down then
						self.is_pressed=true
					end
					self.is_down=true
					self.ticks_down+=1
				else
					self.is_down=false
					self.is_pressed=false
					self.ticks_down=0
				end
			end,
			--state
			is_pressed=false,--pressed this frame
			is_down=false,--currently down
			ticks_down=0,--how long down
		},

		jump_hold_time=0,--how long jump is held
		min_jump_press=5,--min time jump can be held
		max_jump_press=15,--max time jump can be held

		jump_btn_released=true,--can we jump again?
		grounded=false,--on ground

		airtime=0,--time since grounded

		--animation definitions.
		--use with set_anim()
		anims=
		{
			["stand"]=
			{
				ticks=1,--how long is each frame shown.
				frames={1},--what frames are shown.
			},
			["walk"]=
			{
				ticks=5,
				frames={1,2,3,4,5},
			},
			["jump"]=
			{
				ticks=1,
				frames={1},
			},
			["slide"]=
			{
				ticks=1,
				frames={6},
			},
		},

		curanim="walk",--currently playing animation
		curframe=1,--curent frame of animation.
		animtick=0,--ticks until next frame should show.
		flipx=false,--show sprite be flipped.

		--request new animation to play.
		set_anim=function(self,anim)
			if(anim==self.curanim)return--early out.
			local a=self.anims[anim]
			self.animtick=a.ticks--ticks count down.
			self.curanim=anim
			self.curframe=1
		end,

		--call once per tick.
		update=function(self)

			--todo: kill enemies.

			--track button presses
			local bl=btn(0) --left
			local br=btn(1) --right

			--move left/right
			if bl==true then
				self.dx-=self.acc
				br=false--handle double press
			elseif br==true then
				self.dx+=self.acc
			else
				if self.grounded then
					self.dx*=self.dcc
				else
					self.dx*=self.air_dcc
				end
			end

			--limit walk speed
			self.dx=mid(-self.max_dx,self.dx,self.max_dx)

			--move in x
			self.x+=self.dx

			--hit walls
			collide_side(self)

			--jump buttons
			self.jump_button:update()

			--jump is complex.
			--we allow jump if:
			--	on ground
			--	recently on ground
			--	pressed btn right before landing
			--also, jump velocity is
			--not instant. it applies over
			--multiple frames.
			if self.jump_button.is_down then
				--is player on ground recently.
				--allow for jump right after 
				--walking off ledge.
				local on_ground=(self.grounded or self.airtime<5)
				--was btn presses recently?
				--allow for pressing right before
				--hitting ground.
				local new_jump_btn=self.jump_button.ticks_down<10
				--is player continuing a jump
				--or starting a new one?
				if self.jump_hold_time>0 or (on_ground and new_jump_btn) then
					if(self.jump_hold_time==0)sfx(snd.jump)--new jump snd
					self.jump_hold_time+=1
					--keep applying jump velocity
					--until max jump time.
					if self.jump_hold_time<self.max_jump_press then
						self.dy=self.jump_speed--keep going up while held
					end
				end
			else
				self.jump_hold_time=0
			end

			--move in y
			self.dy+=self.grav
			self.dy=mid(-self.max_dy,self.dy,self.max_dy)
			self.y+=self.dy

			--floor
			if not collide_floor(self) then
				self:set_anim("jump")
				self.grounded=false
				self.airtime+=1
			end

			--roof
			collide_roof(self)

			--handle playing correct animation when
			--on the ground.
			if self.grounded then
				if br then
					if self.dx<0 then
						--pressing right but still moving left.
						self:set_anim("slide")
					else
						self:set_anim("walk")
					end
				elseif bl then
					if self.dx>0 then
						--pressing left but still moving right.
						self:set_anim("slide")
					else
						self:set_anim("walk")
					end
				else
					self:set_anim("stand")
				end
			end

			--flip
			if br then
				self.flipx=false
			elseif bl then
				self.flipx=true
			end

			--anim tick
			self.animtick-=1
			if self.animtick<=0 then
				self.curframe+=1
				local a=self.anims[self.curanim]
				self.animtick=a.ticks--reset timer
				if self.curframe>#a.frames then
					self.curframe=1--loop
				end
			end

		end,

		--draw the player
		draw=function(self)
			local a=self.anims[self.curanim]
			local frame=a.frames[self.curframe]
			spr(frame,
				self.x-(self.w/2),
				self.y-(self.h/2),
				self.w/8,self.h/8,
				self.flipx,
				false)
		end,
	}

	return p

end

--make the camera.
function m_cam(target)
	local c=
	{
		tar=target,--target to follow.
		pos=m_vec(target.x,target.y),

		--how far from center of screen target must
		--be before camera starts following.
		--allows for movement in center without camera
		--constantly moving.
		pull_threshold=16,

		--min and max positions of camera
		--the edges of the level.
		pos_min=m_vec(64,64),
		pos_max=m_vec(320,64),

		shake_remaining=0,
		shake_force=0,

		update=function(self)

			self.shake_remaining=max(0,self.shake_remaining-1)

			--follow target outside of
			--pull range.
			if self:pull_max_x()<self.tar.x then
				self.pos.x+=min(self.tar.x-self:pull_max_x(),4)
			end
			if self:pull_min_x()>self.tar.x then
				self.pos.x+=min((self.tar.x-self:pull_min_x()),4)
			end
			if self:pull_max_y()<self.tar.y then
				self.pos.y+=min(self.tar.y-self:pull_max_y(),4)
			end
			if self:pull_min_y()>self.tar.y then
				self.pos.y+=min((self.tar.y-self:pull_min_y()),4)
			end

			--lock to edge
			if(self.pos.x<self.pos_min.x)self.pos.x=self.pos_min.x
			if(self.pos.x>self.pos_max.x)self.pos.x=self.pos_max.x
			if(self.pos.y<self.pos_min.y)self.pos.y=self.pos_min.y
			if(self.pos.y>self.pos_max.y)self.pos.y=self.pos_max.y
		end,

		cam_pos=function(self)
			--calculate camera shake.
			local shk=m_vec(0,0)
			if self.shake_remaining>0 then
				shk.x=rnd(self.shake_force)-(self.shake_force/2)
				shk.y=rnd(self.shake_force)-(self.shake_force/2)
			end
			return self.pos.x-64+shk.x,self.pos.y-64+shk.y
		end,

		pull_max_x=function(self)
			return self.pos.x+self.pull_threshold
		end,

		pull_min_x=function(self)
			return self.pos.x-self.pull_threshold
		end,

		pull_max_y=function(self)
			return self.pos.y+self.pull_threshold
		end,

		pull_min_y=function(self)
			return self.pos.y-self.pull_threshold
		end,

		shake=function(self,ticks,force)
			self.shake_remaining=ticks
			self.shake_force=force
		end
	}

	return c
end

function fire(direc)

	local b = {
		sp=16,
		x = p1.x - 4,
		y = p1.y - 16,
		dx = direc,
		dy = 0
	}

	add (bullets, b)
	isdetonate = false

end

function detonate(x,y)
 	local d = {
			x = x + 4,
			y = y + 4,
			t = 0,
			timer = 0,
		}
		add(det, d)

		detx = d.x
		dety = d.y

 for b in all (bullets) do
		del(bullets, b)
	end
		isdetonate = true;
end

function draw_bullets()
	if(p1.flipx == false) then
		direction = 1
	end
	if(p1.flipx == true) then
		direction = -1
	end

	for b in all (bullets) do
		spr(b.sp, b.x, b.y)
	end
	for d in all (det) do
		circ(d.x, d.y, d.timer/2, d.t)
		circ(d.x, d.y, d.timer/2 - 4, d.t)
	end
end

function draw_clouds()
		map(0,62,detx - 8,dety - 4,2,2)
end

function update_bullets()

		for b in all (bullets) do
			b.x += b.dx
			b.y += b.dy
		end

		if(btnp(4) and isdetonate) then 
			fire(direction)
		end
		if(btnp(5) and isdetonate == false) then
			for b in all (bullets) do
				detonate(b.x, b.y)
			end
		end

		for d in all (det) do
			randcol = flr(rnd(2))
			if(randcol == 0) then
				d.t = 14
			end
			if(randcol == 1) then
				d.t = 7
			end

			d.timer += 1
			if (d.timer == 20) then
				del(det, d)
			end
		end
end

function delete_bullets()
		for b in all (bullets) do
			if(b.x > cam.pos.x + 64 or 
			b.x < cam.pos.x - 64) then
				del(bullets, b)
				isdetonate = true;
			end
		end
end

--game flow
--------------------------------

--reset the game to its initial
--state. use this instead of
--_init()
function reset()
	ticks=0
	p1=m_player(64,40)
	p1:set_anim("walk")
	cam=m_cam(p1)
	bullets = {}
	isdetonate = true
	det = {}
	randcol = 0
	playerx = 0
	playery = 0
	direction = 1
	detx = 500
	dety = 500

end

--p8 functions
--------------------------------

function _init()
	reset()
end

function _update60()
	ticks+=1
	p1:update()
	cam:update()
	--demo camera shake
	update_bullets()
	delete_bullets()
end

function _draw()

	cls(0)
	camera(cam:cam_pos())

	map(0,0,0,0,128,128)

	p1:draw()
	draw_bullets()
	draw_clouds()
	-- debug
	-- camera(0,0)
	-- circ(cam.pos.x, cam.pos.y, 2,7)
	-- printc("adv. micro platformer",64,4,7,0,0)
	-- print(cam.pos.x)
end