local self = {}

local dropdowns = {}

local dropdownValueCache = {}

local maxDropdown = 16

self.openDropdown = 0
local dropdownScroll = 0
local dropdownScrollE = 0

local function skeys(t)
  local k = {}
  for n,v in pairs(t) do table.insert(k, {n, v}) end
  table.sort(k, function(a, b) return a[2].i < b[2].i end)
  local k2 = {}
  for _,v in ipairs(k) do table.insert(k2, v[1]) end
  return k2
end

function self.get(index)
  return dropdowns[index]
end

function self.selected(index)
  return dropdowns[index].options[dropdowns[index].selected]
end

function self.kget(key)
  for _, v in ipairs(dropdowns) do
    if v.name == key then
      return v
    end
  end
end

function self.kselected(key)
  for _, v in ipairs(dropdowns) do
    if v.name == key then
      return v.options[v.selected]
    end
  end
end

local dropdownId
local function insertDropdown(tab, f)
  dropdownId = dropdownId + 1
  f.selected = (self.kget(f.name) or dropdownValueCache[f.name] or {selected = 1}).selected
  f.selected = (f.selected - 1) % #f.options + 1
  return table.insert(tab, f)
end
function self.createDropdowns()
  local d = {}
  dropdownId = 0
  insertDropdown(d, {
    x = padding,
    y = padding,
    width = 128,
    options = {
      'Preview Ease',
      'Mix Eases',
      'Create Ease'
    },
    name = 'mode'
  })

  if d[dropdownId].selected == 1 then -- preview ease
    insertDropdown(d, {
      x = padding + 128 + padding,
      y = padding,
      width = 128,
      options = skeys(eases),
      name = 'ease1'
    })
    ease = eases[d[dropdownId].options[d[dropdownId].selected]].f
  elseif d[dropdownId].selected == 2 then -- mix eases
    insertDropdown(d, {
      x = padding + 128 + padding,
      y = padding,
      width = 128,
      options = skeys(eases),
      name = 'ease1'
    })
    insertDropdown(d, {
      x = padding + 128 + padding + 128 + padding,
      y = padding,
      width = 128,
      options = skeys(eases),
      name = 'ease2'
    })
    ease = mixEase(eases[d[dropdownId - 1].options[d[dropdownId - 1].selected]].f, eases[d[dropdownId].options[d[dropdownId].selected]].f, mixpoint)
  elseif d[dropdownId].selected == 3 then -- create eases
    insertDropdown(d, {
      x = padding + 128 + padding,
      y = padding,
      width = 128,
      options = skeys(eases),
      name = 'ease1'
    })
  end

  dropdowns = d
  minEase = (self.kselected('ease1') and eases[self.kselected('ease1')].min == -1) or (self.kselected('ease2') and eases[self.kselected('ease2')].min == -1)

  return ease, minEase
end

function self.update(dt)
  if self.openDropdown ~= 0 then
    dropdownScroll = math.max(dropdownScroll, -(#self.get(self.openDropdown).options - maxDropdown))
    dropdownScroll = math.min(dropdownScroll, 0)
    dropdownScrollE = mix(dropdownScrollE, dropdownScroll, dt * 10)
  end
end

function self.render()
  local mx, my = love.mouse.getPosition()
  for i,v in ipairs(dropdowns) do
    local x, y, w, h = v.x, v.y, v.width, love.graphics.getFont():getHeight() + margin
    
    love.graphics.setColor(0, 0, 0, 0.3)
    if love.mouse.getX() > x and love.mouse.getX() < x + w and love.mouse.getY() > y and love.mouse.getY() < y + h then
      love.graphics.setColor(0.8, 0.8, 1, love.mouse.isDown(1) and 0.4 or 0.3)
    end
    love.graphics.rectangle('fill', x, y, w, h)
    
    love.graphics.setColor(1, 1, 1, 1)
        
    love.graphics.rectangle('line', x, y, w, h)
    love.graphics.print(self.selected(i), x + margin/2, y + margin/2)
    love.graphics.rectangle('line', x + w - h, y, h, h)
    love.graphics.polygon('line', x + w - h/2 + 0.3 * h, y + h/2 - 0.3 * h, x + w - h/2 - 0.3 * h, y + h/2 - 0.3 * h, x + w - h/2, y + h/2 + 0.3 * h)
    
    if self.openDropdown == i then
      for i,o in ipairs(v.options) do
        local x, y, w, h = x, y + i * h, w, h
        
        y = y + dropdownScrollE * h
        local gi = y / h
        if gi > maxDropdown or gi < 1 then
          goto continue
        end
        
        local a = 1 - math.min(math.max((1 - (maxDropdown - gi)) * (1 - (math.abs(dropdownScrollE) /(#v.options - maxDropdown))), 0), 1)
      
        love.graphics.setColor(0, 0, 0, 0.3 * a)
        if mx > x and mx < x + w and my > y and my < y + h then
          love.graphics.setColor(0.8, 0.8, 1, (love.mouse.isDown(1) and 0.4 or 0.3) * a)
        end
        love.graphics.rectangle('fill', x, y, w, h)
      
        love.graphics.setColor(1, 1, 1, 0.75 * a)
        love.graphics.rectangle('line', x, y, w, h)
        
        love.graphics.setColor(1, 1, 1, 1 * a)
        love.graphics.print(v.options[i], x + 2, y + 2)
        
        ::continue::
      end
      
      -- scrollwheel
    
      if #v.options > maxDropdown then
        local displayed = maxDropdown / #v.options
        local scroll = math.abs(dropdownScrollE) / (#v.options - maxDropdown)
        local size = margin
      
        love.graphics.setColor(1, 1, 1, 0.9)
        love.graphics.rectangle('fill', x + w - size, y + h + scroll * (1 - displayed) * (maxDropdown - 1) * h, size, displayed * (maxDropdown - 1) * h)
      end
    end
  end
end

function self.mousepressed(x, y, m)
  local clickedDropdown = false
  for i,v in ipairs(dropdowns) do
    local h = love.graphics.getFont():getHeight() + margin
    if self.openDropdown == 0 then
      if x > v.x and x < v.x + v.width and y > v.y and y < v.y + h + margin then
        if m == 1 then
          self.openDropdown = i
          clickedDropdown = true
          dropdownScroll = 0
          dropdownScrollE = 0
        elseif m == 3 then
          dropdowns[i].selected = math.random(1, #dropdowns[i].options)
          self.createDropdowns()
        end
      end
    elseif self.openDropdown == i then
      if x > v.x and x < v.x + v.width and y > v.y + h and y < v.y + h * (math.min(#v.options, maxDropdown) + 1) and m == 1 then
        clickedDropdown = true
      end
    end
  end
  
  if not clickedDropdown and m == 1 then
    self.openDropdown = 0
    return true
  end
end

function self.mousereleased(x, y, m)
  for i,v in ipairs(dropdowns) do
    local h = love.graphics.getFont():getHeight() + margin
    if self.openDropdown == i then
      if x > v.x and x < v.x + v.width and y > v.y + h and y < v.y + h * (math.min(#v.options, maxDropdown) + 1) and m == 1 then
        v.selected = math.floor((y - v.y) / h - dropdownScrollE)
        self.openDropdown = 0
        dropdownValueCache[v.name] = {selected = v.selected}
        self.createDropdowns()
      end
    end
  end
end

function self.wheelmoved(x, y)
  if self.openDropdown ~= 0 then
    dropdownScroll = dropdownScroll + y
  else
    local mx, my = love.mouse.getPosition()
    for i,v in ipairs(dropdowns) do
      local h = love.graphics.getFont():getHeight() + margin
      if mx > v.x and mx < v.x + v.width and my > v.y and my < v.y + h + margin then
        dropdowns[i].selected = dropdowns[i].selected - math.floor(y)
        dropdowns[i].selected = (dropdowns[i].selected - 1) % #dropdowns[i].options + 1
        self.createDropdowns()
      end
    end
  end
end

return self