refactor: cleanup diff highlights (#247)

make sure to run on scheme change

Signed-off-by: Aaron Pham <contact@aarnphm.xyz>

lua/avante/highlights.lua

@@ -1,8 +1,10 @@
 local api = vim.api
 
 local Config = require("avante.config")
+local bit = require("bit")
+local rshift, band = bit.rshift, bit.band
 
-local H = {
+local Highlights = {
   TITLE = { name = "AvanteTitle", fg = "#1e222a", bg = "#98c379" },
   REVERSED_TITLE = { name = "AvanteReversedTitle", fg = "#98c379" },
   SUBTITLE = { name = "AvanteSubtitle", fg = "#1e222a", bg = "#56b6c2" },
@@ -11,6 +13,18 @@ local H = {
   REVERSED_THIRD_TITLE = { name = "AvanteReversedThirdTitle", fg = "#353B45" },
 }
 
+Highlights.conflict = {
+  CURRENT = { name = "AvanteConflictCurrent", bg = 4218238 }, -- #405d7e
+  CURRENT_LABEL = { name = "AvanteConflictCurrentLabel", link = "CURRENT", shade = 60 },
+  INCOMING = { name = "AvanteConflictIncoming", bg = 3229523 }, -- #314753
+  INCOMING_LABEL = { name = "AvanteConflictIncomingLabel", link = "INCOMING", shade = 60 },
+  ANCESTOR = { name = "AvanteConflictAncestor", bg = 6824314 }, -- #68217A
+  ANCESTOR_LABEL = { name = "AvanteConflictAncestorLabel", link = "ANCESTOR", shade = 60 },
+}
+
+--- helper
+local H = {}
+
 local M = {}
 
 M.input_ns = api.nvim_create_namespace("avante_input")
@@ -26,26 +40,95 @@ M.setup = function()
   local normal_float = api.nvim_get_hl(0, { name = "NormalFloat" })
 
   if Config.behaviour.auto_set_highlight_group then
-    vim.iter(H):each(function(_, hl)
-      if not has_set_colors(hl.name) then
-        api.nvim_set_hl(0, hl.name, { fg = hl.fg, bg = hl.bg or nil })
-      end
-    end)
+    vim
+      .iter(Highlights)
+      :filter(function(k, _)
+        -- return all uppercase key with underscore or fully uppercase key
+        return k:match("^%u+_") or k:match("^%u+$")
+      end)
+      :each(function(_, hl)
+        if not has_set_colors(hl.name) then
+          api.nvim_set_hl(0, hl.name, { fg = hl.fg or nil, bg = hl.bg or nil })
+        end
+      end)
+
+    M.conflict_highlights()
   end
 
   api.nvim_set_hl(M.hint_ns, "NormalFloat", { fg = normal_float.fg, bg = normal_float.bg })
-
   api.nvim_set_hl(M.input_ns, "NormalFloat", { fg = normal_float.fg, bg = normal_float.bg })
   api.nvim_set_hl(M.input_ns, "FloatBorder", { fg = normal.fg, bg = normal.bg })
 end
 
+---@param opts? AvanteConflictHighlights
+M.conflict_highlights = function(opts)
+  opts = opts or Config.diff.highlights
+
+  local get_default_colors = function(key, hl)
+    local getter = api.nvim_get_hl(0, { name = opts[key:lower()] })
+    return getter.bg or hl.bg
+  end
+
+  local get_shade = function(hl)
+    local color = get_default_colors(hl.link, Highlights.conflict[hl.link])
+    return H.shade_color(color, hl.shade)
+  end
+
+  vim.iter(Highlights.conflict):each(function(key, hl)
+    if not has_set_colors(hl.name) then
+      if hl.link ~= nil then
+        api.nvim_set_hl(0, hl.name, { bg = get_shade(hl), default = true })
+      else
+        api.nvim_set_hl(0, hl.name, { bg = get_default_colors(key, hl), default = true, bold = true })
+      end
+    end
+  end)
+end
+
 setmetatable(M, {
   __index = function(t, k)
-    if H[k] ~= nil then
-      return H[k].name
+    if Highlights[k] ~= nil then
+      return Highlights[k].name
+    elseif Highlights.conflict[k] ~= nil then
+      return Highlights.conflict[k].name
     end
     return t[k]
   end,
 })
 
+--- Returns a table containing the RGB values encoded inside 24 least
+--- significant bits of the number @rgb_24bit
+---
+---@param rgb_24bit number 24-bit RGB value
+---@return {r: integer, g: integer, b: integer} with keys 'r', 'g', 'b' in [0,255]
+H.decode_24bit_rgb = function(rgb_24bit)
+  vim.validate({ rgb_24bit = { rgb_24bit, "n", true } })
+  local r = band(rshift(rgb_24bit, 16), 255)
+  local g = band(rshift(rgb_24bit, 8), 255)
+  local b = band(rgb_24bit, 255)
+  return { r = r, g = g, b = b }
+end
+
+---@param attr integer
+---@param percent integer
+H.alter = function(attr, percent)
+  return math.floor(attr * (100 + percent) / 100)
+end
+
+---@source https://stackoverflow.com/q/5560248
+---@see https://stackoverflow.com/a/37797380
+---Darken a specified hex color
+---@param color number
+---@param percent number
+---@return string
+H.shade_color = function(color, percent)
+  local rgb = H.decode_24bit_rgb(color)
+  if not rgb.r or not rgb.g or not rgb.b then
+    return "NONE"
+  end
+  local r, g, b = H.alter(rgb.r, percent), H.alter(rgb.g, percent), H.alter(rgb.b, percent)
+  r, g, b = math.min(r, 255), math.min(g, 255), math.min(b, 255)
+  return string.format("#%02x%02x%02x", r, g, b)
+end
+
 return M