-- Color picker logic, ported from the C callbacks that used to live in editor.c
--
-- Layer 0 elements:
--   0     background
--   1     sv square       (HSV rect, hue in color channel 0)
--   2     hue bar         (HSV rect)
--   3     sv select outline
--   4     sv select       (HSV rect)
--   5     hex string input area
--   6     hue select bar
--   7-18  saved color slots

local state = {
  hsv = {0, 0, 0},
  rgb = {0, 0, 0, 1},
  saved = {},
  hex_string = "#000000FF",
  hex_len = 8,
}
for i = 1, 12 do state.saved[i] = {0, 0, 0, 0} end

local function update_hex_string()
  state.hex_string = string.format("#%02X%02X%02X%02X",
      math.floor(state.rgb[1]*255 + 0.5),
      math.floor(state.rgb[2]*255 + 0.5),
      math.floor(state.rgb[3]*255 + 0.5),
      math.floor(state.rgb[4]*255 + 0.5))
  state.hex_len = 8
  ui.set_string(0, 0, state.hex_string)
end

local function sv_pick(s, v)
  s = math.max(0, math.min(1, s))
  v = math.max(0, math.min(1, v))
  state.hsv[2] = s
  state.hsv[3] = v

  ui.set_pos(0, 4, s*130 - 2, 130 - v*130 - 2)
  for corner = 0, 3 do
    ui.set_corner_color(0, 4, corner, state.hsv[1], s, v, 1)
  end
  ui.set_pos(0, 3, s*130 - 3, 130 - v*130 - 3)

  state.rgb[1], state.rgb[2], state.rgb[3] =
      ui.hsv_to_rgb(state.hsv[1], state.hsv[2], state.hsv[3])
  update_hex_string()
end

local function hue_set(h)
  h = math.max(0, math.min(1, h))
  state.hsv[1] = h

  -- sv square and sv select keep their per-corner s/v, only hue changes
  for _, drawable in ipairs({1, 4}) do
    for corner = 0, 3 do
      local _, s, v, a = ui.get_corner_color(0, drawable, corner)
      ui.set_corner_color(0, drawable, corner, h, s, v, a)
    end
  end
  ui.set_pos(0, 6, 134, 2 + h*130)

  state.rgb[1], state.rgb[2], state.rgb[3] =
      ui.hsv_to_rgb(state.hsv[1], state.hsv[2], state.hsv[3])
  update_hex_string()
end

local function hex_string_highlight(value)
  for corner = 0, 3 do
    local r, g, _, _ = ui.get_corner_color(0, 5, corner)
    ui.set_corner_color(0, 5, corner, r, g, value, value)
  end
end

local function set_saved(index, color)
  state.saved[index] = {color[1], color[2], color[3], color[4]}
  local element = 6 + index
  for corner = 0, 3 do
    local _, _, _, a = ui.get_corner_color(0, element, corner)
    ui.set_corner_color(0, element, corner, color[1], color[2], color[3], a)
  end
end

function on_button(layer, element, x, y, button, action, mods)
  if element == 1 then  -- sv square
    if action == PRESS and button == MOUSE_LEFT then
      ui.focus(layer, element)
      sv_pick(x, 1 - y)
    elseif action == RELEASE and button == MOUSE_LEFT then
      ui.blur()
    end
    return true

  elseif element == 2 then  -- hue bar
    if action == PRESS and button == MOUSE_LEFT then
      ui.focus(layer, element)
      hue_set(y)
    elseif action == RELEASE and button == MOUSE_LEFT then
      ui.blur()
    end
    return true

  elseif element == 5 then  -- hex string input
    if action == PRESS and button == MOUSE_LEFT then
      ui.focus(layer, element)
      hex_string_highlight(1)
    end
    return true

  elseif element >= 7 and element <= 18 then  -- saved color slots
    local index = element - 6
    if action == PRESS then
      if button == MOUSE_LEFT then
        local saved = state.saved[index]
        state.rgb = {saved[1], saved[2], saved[3], saved[4]}
        state.hsv[1], state.hsv[2], state.hsv[3] =
            ui.rgb_to_hsv(state.rgb[1], state.rgb[2], state.rgb[3])
        hue_set(state.hsv[1])
        sv_pick(state.hsv[2], state.hsv[3])
      elseif button == MOUSE_RIGHT then
        set_saved(index, state.rgb)
      elseif button == MOUSE_MIDDLE then
        set_saved(index, {0, 0, 0, 0})
      end
    end
    return true
  end

  return false
end

function on_cursor(layer, element, x, y)
  if ui.is_focused(0, 1) then      -- dragging the sv square
    sv_pick(x, 1 - y)
    return true
  elseif ui.is_focused(0, 2) then  -- dragging the hue bar
    hue_set(y)
    return true
  end
  return false
end

function on_scroll(layer, element, x, y)
  if element == 2 then  -- hue bar
    hue_set(state.hsv[1] + y*0.01)
    return true
  end
  return false
end

function on_key(layer, element, key, action, mods)
  if element ~= 5 then return false end

  if action == PRESS then
    if key == KEY_ESCAPE then
      state.rgb[1], state.rgb[2], state.rgb[3] =
          ui.hsv_to_rgb(state.hsv[1], state.hsv[2], state.hsv[3])
      update_hex_string()
      ui.blur()
    elseif key == KEY_ENTER then
      local s = state.hex_string
      state.rgb[1] = (tonumber(s:sub(2, 3), 16) or 0) / 255
      state.rgb[2] = (tonumber(s:sub(4, 5), 16) or 0) / 255
      state.rgb[3] = (tonumber(s:sub(6, 7), 16) or 0) / 255
      state.rgb[4] = (tonumber(s:sub(8, 9), 16) or 0) / 255
      state.hsv[1], state.hsv[2], state.hsv[3] =
          ui.rgb_to_hsv(state.rgb[1], state.rgb[2], state.rgb[3])
      hue_set(state.hsv[1])
      sv_pick(state.hsv[2], state.hsv[3])
      ui.blur()
    elseif key == KEY_BACKSPACE then
      if state.hex_len > 0 then
        state.hex_string = state.hex_string:sub(1, state.hex_len)
        state.hex_len = state.hex_len - 1
        ui.set_string(0, 0, state.hex_string)
      end
    end
  end

  -- consume all keys while the hex input is focused
  return true
end

function on_text(layer, element, codepoint)
  if element ~= 5 then return false end

  if codepoint < 128 then
    local ch = string.char(codepoint):upper()
    if ch:match("[0-9A-F]") and state.hex_len < 8 then
      state.hex_string = state.hex_string .. ch
      state.hex_len = state.hex_len + 1
      ui.set_string(0, 0, state.hex_string)
    end
  end
  return true
end

function on_deselect(layer, element)
  if element == 5 then
    hex_string_highlight(0)
  end
end

-- runs once at container load
ui.set_string(0, 0, state.hex_string)