Fix colors

lua/winshift/colors.lua

@@ -110,31 +110,53 @@ end
 
 ---@param group string Syntax group name.
 ---@param opt HiSpec
+
+
 function M.hi(group, opt)
   local use_tc = vim.o.termguicolors
   local g = use_tc and "gui" or "cterm"
 
+  -- Check if highlight group exists; if not, create a basic version of it
+  local exists = vim.fn.hlexists(group)
+  if not exists then
+    vim.cmd("hi " .. group .. " ctermfg=NONE ctermbg=NONE guifg=NONE guibg=NONE")
+  end
+
+  local cmd = "hi " .. (opt.default and "def " or "") .. group
+
   if not use_tc then
     if opt.ctermfg then
       opt.fg = opt.ctermfg
+      cmd = cmd .. " ctermfg=" .. opt.fg
     end
     if opt.ctermbg then
       opt.bg = opt.ctermbg
+      cmd = cmd .. " ctermbg=" .. opt.bg
+    end
+  else
+    if opt.fg then
+      cmd = cmd .. " guifg=" .. opt.fg
+    end
+    if opt.bg then
+      cmd = cmd .. " guibg=" .. opt.bg
     end
   end
 
-  vim.cmd(string.format(
-    "hi %s %s %s %s %s %s %s",
-    opt.default and "def" or "",
-    group,
-    opt.fg and (g .. "fg=" .. opt.fg) or "",
-    opt.bg and (g .. "bg=" .. opt.bg) or "",
-    opt.gui and ((use_tc and "gui=" or "cterm=") .. opt.gui) or "",
-    opt.sp and ("guisp=" .. opt.sp) or "",
-    opt.blend and ("blend=" .. opt.blend) or ""
-  ))
+  if opt.gui then
+    cmd = cmd .. " " .. (use_tc and "gui=" or "cterm=") .. opt.gui
+  end
+  if opt.sp then
+    cmd = cmd .. " guisp=" .. opt.sp
+  end
+  if opt.blend then
+    cmd = cmd .. " blend=" .. opt.blend
+  end
+
+  vim.cmd(cmd)
 end
 
+
+
 ---@param from string Syntax group name.
 ---@param to? string Syntax group name. (default: `"NONE"`)
 ---@param opt? HiLinkSpec
@@ -187,6 +209,78 @@ M.hl_links = {
   LineNrBelow = "WinShiftLineNr",
 }
 
+------------------------ begin ISC licensed code
+-- translated from the code found in colour.c in tmux
+
+-- Copyright (c) 2008 Nicholas Marriott <nicholas.marriott@gmail.com>
+-- Copyright (c) 2016 Avi Halachmi <avihpit@yahoo.com>
+
+-- Permission to use, copy, modify, and distribute this software for any
+-- purpose with or without fee is hereby granted, provided that the above
+-- copyright notice and this permission notice appear in all copies.
+-- 
+-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+-- ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+-- ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+-- OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+
+local function hex_to_rgb(hex)
+  -- Check if the input is a string
+  if type(hex) ~= "string" then
+    return nil
+  end
+
+  if string.match(hex, "^#%x%x%x%x%x%x$") then
+    local r, g, b = hex:match("#(%x%x)(%x%x)(%x%x)")
+    return tonumber(r, 16), tonumber(g, 16), tonumber(b, 16)
+  else
+    return nil, nil, nil
+  end
+end
+
+function M.v2ci(v)
+  if v < 48 then return 0
+  elseif v < 115 then return 1
+  else return math.floor((v - 35) / 40)
+  end
+end
+
+function M.color_index(ir, ig, ib)
+  return 36 * ir + 6 * ig + ib
+end
+
+function M.dist_square(A, B, C, a, b, c)
+  return (A-a)^2 + (B-b)^2 + (C-c)^2
+end
+
+-- checkss if input is a  hex value, if it is return a similar 256 value integer, else return nil
+function M.rgbtox256(hex)
+  local r, g, b = hex_to_rgb(hex)
+  if r == nil then return nil end
+
+  local ir, ig, ib = M.v2ci(r), M.v2ci(g), M.v2ci(b)
+  local average = (r + g + b) / 3
+  local gray_index = average > 238 and 23 or math.floor((average - 3) / 10)
+  local i2cv = {0, 0x5f, 0x87, 0xaf, 0xd7, 0xff}
+  local cr, cg, cb = i2cv[ir + 1], i2cv[ig + 1], i2cv[ib + 1]
+  local gv = 8 + 10 * gray_index
+
+  local color_err = M.dist_square(cr, cg, cb, r, g, b)
+  local gray_err = M.dist_square(gv, gv, gv, r, g, b)
+
+  if color_err <= gray_err then
+    return 16 + M.color_index(ir, ig, ib)
+  else
+    return 232 + gray_index
+  end
+end
+---------------------- end ISC licensed code
+
+
 function M.setup()
   for name, opt in pairs(M.get_hl_groups()) do
     M.hi("WinShift" .. name, opt)