local lg = love.graphics

local t = {
  name = "",
  tooltip = "",
  icon = false,
  lit = false,
  x = 8,
  y = 250,
  w = 13 * 28 - 4,
  h = 24,
  group = false,
  visible = false,
  align = "center",
  callback = function( self ) return print( "clicked button: ", self.name, self.x, self.y, self.w, self.h, self.visible ) end
}
t.selected, t.next, t.prev = t, t, t

function t.contains( button, x, y )
  return x < button.x + button.w and x > button.x
  and    y < button.y + button.h and y > button.y
end


function t.new( b )
  b = setmetatable( b or {}, t )
  b.next = t
  t.prev.next = b
  b.prev = t.prev
  t.prev = b
  return b
end

function t.highlight( b )
  lg.rectangle( "fill", b.x, b.y, b.w, b.h )
end

local drawPassOngoing = false
function t.draw( b )
  if b == t then
    drawPassOngoing = not( drawPassOngoing )
    if not drawPassOngoing then return end
  elseif b.visible then
    lg.rectangle( "line", b.x, b.y, b.w, b.h )
    lg.printf( b.name,
      b.x + (b.icon and b.h or 0),
      b.y + 0.5 * ( b.h - lg.getFont():getHeight() ),
      b.w - (b.icon and b.h or 0),
      b.align )
    if b.icon then 
      local h = b.icon:getHeight()
      lg.draw( b.icon,
        b.x, b.y,
        0,
        b.h / h )
    end
    if b.lit or t.selected == b then
      b:highlight()
    end
  end
  return t.draw( b.next )
end

function t.select( b )
  t.selected = b
end

function t.selectNext()
  repeat t.selected = t.selected.next until (t.selected == t) or t.selected.visible
end

function t.selectPrev()
  repeat t.selected = t.selected.prev until (t.selected == t) or t.selected.visible
end

function t.selectIn( x, y )
  t.selected = t
  repeat t.selected = t.selected.next until (t.selected == t) or (t.selected.visible and t.selected:contains( x, y ))
end

function t.selectNextInGroup()
  --make sure our group is visible, otherwise the loop doesn't end
  local group = t.selected 
  group = group and t.selected.visible
  group = group and t.selected.group
  if not group then return t.selectNext() end
  repeat t.selectNext() until group == t.selected.group
end

function t.selectPrevInGroup()
  --make sure our group is visible, otherwise the loop doesn't end
  local group = t.selected and t.selected.visible and t.selected.group
  if not group then return t.selectPrev() end
  repeat t.selectPrev() until group == t.selected.group
end

--show/hide all buttons in a group
--passing hide=true will hide the group, hide=false or nil will show the group
--solo=true will hide all buttons outside the group
function t.displayGroup( group, hide, solo )
  local b = t
  repeat 
    b = b.next
    local inGroup = (group == b.group)
    if solo or inGroup then
      b.visible = not(hide) and inGroup
    end
  until b == t
  t.visible = true
end

function t.mousepressed( x, y )
  if t.selected and t.selected:contains( x, y ) then
    return t.selected:callback()
  end
end

function t.deselect( b )
  t.selected = t
end

setmetatable( t, t )
t.__index = t
t.__call = t.new

return t