Inside nvim.

return {
   "uga-rosa/ccc.nvim",
   config = function()
      vim.opt.termguicolors = true
      local ColorInput = require("ccc.input")
      local convert = require("ccc.utils.convert")

      -- HSL/RGB input

      local HslRgbInput = setmetatable({
         name = "HSL/RGB",
         max = { 360, 1, 1, 1, 1, 1 },
         min = { 0, 0, 0, 0, 0, 0 },
         delta = { 1, 0.01, 0.01, 1 / 255, 1 / 255, 1 / 255 },
         bar_name = { "H", "S", "L", "R", "G", "B" },
      }, { __index = ColorInput })

      function HslRgbInput.format(n, i)
         if i >= 4 then
            -- RGB
            n = n * 255
         elseif i == 2 or i == 3 then
            -- S or L of HSL
            n = n * 100
         end
         return ("%6d"):format(n)
      end

      function HslRgbInput.from_rgb(RGB)
         local HSL = convert.rgb2hsl(RGB)
         local R, G, B = unpack(RGB)
         local H, S, L = unpack(HSL)
         return { H, S, L, R, G, B }
      end

      function HslRgbInput.to_rgb(value)
         return { value[4], value[5], value[6] }
      end

      function HslRgbInput:_set_rgb(RGB)
         self.value[4] = RGB[1]
         self.value[5] = RGB[2]
         self.value[6] = RGB[3]
      end

      function HslRgbInput:_set_hsl(HSL)
         self.value[1] = HSL[1]
         self.value[2] = HSL[2]
         self.value[3] = HSL[3]
      end

      function HslRgbInput:callback(index, new_value)
         self.value[index] = new_value
         local v = self.value
         if index >= 4 then
            local RGB = { v[4], v[5], v[6] }
            local HSL = convert.rgb2hsl(RGB)
            self:_set_hsl(HSL)
         else
            local HSL = { v[1], v[2], v[3] }
            local RGB = convert.hsl2rgb(HSL)
            self:_set_rgb(RGB)
         end
      end

      -- config

      local ccc = require("ccc")
      local mapping = ccc.mapping

      ccc.setup({
         highlighter = {
            auto_enable = true,
            lsp = true,
         },
         inputs = {
            HslRgbInput,
         },
         alpha_show = "never",
      })

      vim.api.nvim_set_keymap("n", "<leader>cp", ":CccPick<CR>", { noremap = true, silent = true, desc = "Pick color" })
      vim.api.nvim_set_keymap(
         "n",
         "<leader>ct",
         ":CccHighlighterToggle<CR>",
         { noremap = true, silent = true, desc = "Toggle color highlighter" }
      )
      vim.api.nvim_set_keymap(
         "n",
         "<leader>cn",
         ":CccConvert<CR>",
         { noremap = true, silent = true, desc = "Convert color" }
      )
      vim.api.nvim_create_user_command("CccHighlighterToggleTwice", function()
         vim.cmd("CccHighlighterToggle")
         vim.cmd("CccHighlighterToggle")
      end, {})
      vim.api.nvim_set_keymap(
         "n",
         "<leader>cr",
         ":CccHighlighterToggleTwice<CR>",
         { noremap = true, silent = true, desc = "Refresh color highlighter" }
      )
   end,
}