1 files changed, 405 insertions, 0 deletions
diff --git a/lua/colorizer/color.lua b/lua/colorizer/color.lua
new file mode 100644
index 0000000..711c8e4
--- /dev/null
+++ b/lua/colorizer/color.lua
@@ -0,0 +1,405 @@
+---Helper functions to parse different colour formats
+--@module colorizer.color
+local api = vim.api
+
+local bit = require "bit"
+local floor, min, max = math.floor, math.min, math.max
+local band, rshift, lshift, tohex = bit.band, bit.rshift, bit.lshift, bit.tohex
+
+local Trie = require "colorizer.trie"
+
+local utils = require "colorizer.utils"
+local byte_is_alphanumeric = utils.byte_is_alphanumeric
+local byte_is_hex = utils.byte_is_hex
+local parse_hex = utils.parse_hex
+local percent_or_hex = utils.percent_or_hex
+
+local color = {}
+
+local ARGB_MINIMUM_LENGTH = #"0xAARRGGBB" - 1
+---parse for 0xaarrggbb and return rgb hex.
+-- a format used in android apps
+---@param line string: line to parse
+---@param i number: index of line from where to start parsing
+---@return number|nil: index of line where the hex value ended
+---@return string|nil: rgb hex value
+function color.argb_hex_parser(line, i)
+  if #line < i + ARGB_MINIMUM_LENGTH then
+    return
+  end
+
+  local j = i + 2
+
+  local n = j + 8
+  local alpha
+  local v = 0
+  while j <= min(n, #line) do
+    local b = line:byte(j)
+    if not byte_is_hex(b) then
+      break
+    end
+    if j - i <= 3 then
+      alpha = parse_hex(b) + lshift(alpha or 0, 4)
+    else
+      v = parse_hex(b) + lshift(v, 4)
+    end
+    j = j + 1
+  end
+  if #line >= j and byte_is_alphanumeric(line:byte(j)) then
+    return
+  end
+  local length = j - i
+  if length ~= 10 then
+    return
+  end
+  alpha = tonumber(alpha) / 255
+  local r = floor(band(rshift(v, 16), 0xFF) * alpha)
+  local g = floor(band(rshift(v, 8), 0xFF) * alpha)
+  local b = floor(band(v, 0xFF) * alpha)
+  local rgb_hex = string.format("%02x%02x%02x", r, g, b)
+  return length, rgb_hex
+end
+
+--- Converts an HSL color value to RGB.
+---@param h number: Hue
+---@param s number: Saturation
+---@param l number: Lightness
+---@return number|nil,number|nil,number|nil
+function color.hsl_to_rgb(h, s, l)
+  if h > 1 or s > 1 or l > 1 then
+    return
+  end
+  if s == 0 then
+    local r = l * 255
+    return r, r, r
+  end
+  local q
+  if l < 0.5 then
+    q = l * (1 + s)
+  else
+    q = l + s - l * s
+  end
+  local p = 2 * l - q
+  return 255 * color.hue_to_rgb(p, q, h + 1 / 3),
+    255 * color.hue_to_rgb(p, q, h),
+    255 * color.hue_to_rgb(p, q, h - 1 / 3)
+end
+
+local CSS_HSL_FN_MINIMUM_LENGTH = #"hsl(0,0%,0%)" - 1
+---Parse for hsl() css function and return rgb hex.
+---@param line string: Line to parse
+---@param i number: Index of line from where to start parsing
+---@return number|nil: Index of line where the hsl function ended
+---@return string|nil: rgb hex value
+function color.hsl_function_parser(line, i)
+  if #line < i + CSS_HSL_FN_MINIMUM_LENGTH then
+    return
+  end
+  local h, s, l, match_end = line:sub(i):match "^hsl%(%s*(%d+)%s*,%s*(%d+)%%%s*,%s*(%d+)%%%s*%)()"
+  if not match_end then
+    h, s, l, match_end = line:sub(i):match "^hsl%(%s*(%d+)%s+(%d+)%%%s+(%d+)%%%s*%)()"
+    if not match_end then
+      return
+    end
+  end
+  h = tonumber(h)
+  if h > 360 then
+    return
+  end
+  s = tonumber(s)
+  if s > 100 then
+    return
+  end
+  l = tonumber(l)
+  if l > 100 then
+    return
+  end
+  local r, g, b = color.hsl_to_rgb(h / 360, s / 100, l / 100)
+  if r == nil or g == nil or b == nil then
+    return
+  end
+  local rgb_hex = string.format("%02x%02x%02x", r, g, b)
+  return match_end - 1, rgb_hex
+end
+
+local CSS_HSLA_FN_MINIMUM_LENGTH = #"hsla(0,0%,0%,0)" - 1
+---Parse for hsl() css function and return rgb hex.
+---@param line string: Line to parse
+---@param i number: Index of line from where to start parsing
+---@return number|nil: Index of line where the hsla function ended
+---@return string|nil: rgb hex value
+function color.hsla_function_parser(line, i)
+  if #line < i + CSS_HSLA_FN_MINIMUM_LENGTH then
+    return
+  end
+  local h, s, l, a, match_end = line:sub(i):match "^hsla%(%s*(%d+)%s*,%s*(%d+)%%%s*,%s*(%d+)%%%s*,%s*([.%d]+)%s*%)()"
+  if not match_end then
+    h, s, l, a, match_end = line:sub(i):match "^hsla%(%s*(%d+)%s+(%d+)%%%s+(%d+)%%%s+([.%d]+)%s*%)()"
+    if not match_end then
+      return
+    end
+  end
+  a = tonumber(a)
+  if not a or a > 1 then
+    return
+  end
+  h = tonumber(h)
+  if h > 360 then
+    return
+  end
+  s = tonumber(s)
+  if s > 100 then
+    return
+  end
+  l = tonumber(l)
+  if l > 100 then
+    return
+  end
+  local r, g, b = color.hsl_to_rgb(h / 360, s / 100, l / 100)
+  if r == nil or g == nil or b == nil then
+    return
+  end
+  local rgb_hex = string.format("%02x%02x%02x", r * a, g * a, b * a)
+  return match_end - 1, rgb_hex
+end
+
+---Convert hsl colour values to rgb.
+-- Source: https://gist.github.com/mjackson/5311256
+---@param p number
+---@param q number
+---@param t number
+---@return number
+function color.hue_to_rgb(p, q, t)
+  if t < 0 then
+    t = t + 1
+  end
+  if t > 1 then
+    t = t - 1
+  end
+  if t < 1 / 6 then
+    return p + (q - p) * 6 * t
+  end
+  if t < 1 / 2 then
+    return q
+  end
+  if t < 2 / 3 then
+    return p + (q - p) * (2 / 3 - t) * 6
+  end
+  return p
+end
+
+---Determine whether to use black or white text.
+--
+-- ref: https://stackoverflow.com/a/1855903/837964
+-- https://stackoverflow.com/questions/596216/formula-to-determine-brightness-of-rgb-color
+---@param r number: Red
+---@param g number: Green
+---@param b number: Blue
+function color.is_bright(r, g, b)
+  -- counting the perceptive luminance - human eye favors green color
+  local luminance = (0.299 * r + 0.587 * g + 0.114 * b) / 255
+  if luminance > 0.5 then
+    return true -- bright colors, black font
+  else
+    return false -- dark colors, white font
+  end
+end
+
+local COLOR_MAP
+local COLOR_TRIE
+local COLOR_NAME_MINLEN, COLOR_NAME_MAXLEN
+local COLOR_NAME_SETTINGS = { lowercase = true, strip_digits = false }
+local TAILWIND_ENABLED = false
+--- Grab all the colour values from `vim.api.nvim_get_color_map` and create a lookup table.
+-- COLOR_MAP is used to store the colour values
+---@param line string: Line to parse
+---@param i number: Index of line from where to start parsing
+---@param opts table: Currently contains whether tailwind is enabled or not
+function color.name_parser(line, i, opts)
+  --- Setup the COLOR_MAP and COLOR_TRIE
+  if not COLOR_TRIE or opts.tailwind ~= TAILWIND_ENABLED then
+    COLOR_MAP = {}
+    COLOR_TRIE = Trie()
+    for k, v in pairs(api.nvim_get_color_map()) do
+      if not (COLOR_NAME_SETTINGS.strip_digits and k:match "%d+$") then
+        COLOR_NAME_MINLEN = COLOR_NAME_MINLEN and min(#k, COLOR_NAME_MINLEN) or #k
+        COLOR_NAME_MAXLEN = COLOR_NAME_MAXLEN and max(#k, COLOR_NAME_MAXLEN) or #k
+        local rgb_hex = tohex(v, 6)
+        COLOR_MAP[k] = rgb_hex
+        COLOR_TRIE:insert(k)
+        if COLOR_NAME_SETTINGS.lowercase then
+          local lowercase = k:lower()
+          COLOR_MAP[lowercase] = rgb_hex
+          COLOR_TRIE:insert(lowercase)
+        end
+      end
+    end
+    if opts and opts.tailwind then
+      if opts.tailwind == true or opts.tailwind == "normal" or opts.tailwind == "both" then
+        local tailwind = require "colorizer.tailwind_colors"
+        -- setup tailwind colors
+        for k, v in pairs(tailwind.colors) do
+          for _, pre in ipairs(tailwind.prefixes) do
+            local name = pre .. "-" .. k
+            COLOR_NAME_MINLEN = COLOR_NAME_MINLEN and min(#name, COLOR_NAME_MINLEN) or #name
+            COLOR_NAME_MAXLEN = COLOR_NAME_MAXLEN and max(#name, COLOR_NAME_MAXLEN) or #name
+            COLOR_MAP[name] = v
+            COLOR_TRIE:insert(name)
+          end
+        end
+      end
+    end
+    TAILWIND_ENABLED = opts.tailwind
+  end
+
+  if #line < i + COLOR_NAME_MINLEN - 1 then
+    return
+  end
+
+  if i > 1 and byte_is_alphanumeric(line:byte(i - 1)) then
+    return
+  end
+
+  local prefix = COLOR_TRIE:longest_prefix(line, i)
+  if prefix then
+    -- Check if there is a letter here so as to disallow matching here.
+    -- Take the Blue out of Blueberry
+    -- Line end or non-letter.
+    local next_byte_index = i + #prefix
+    if #line >= next_byte_index and byte_is_alphanumeric(line:byte(next_byte_index)) then
+      return
+    end
+    return #prefix, COLOR_MAP[prefix]
+  end
+end
+
+local CSS_RGB_FN_MINIMUM_LENGTH = #"rgb(0,0,0)" - 1
+---Parse for rgb() css function and return rgb hex.
+---@param line string: Line to parse
+---@param i number: Index of line from where to start parsing
+---@return number|nil: Index of line where the rgb function ended
+---@return string|nil: rgb hex value
+function color.rgb_function_parser(line, i)
+  if #line < i + CSS_RGB_FN_MINIMUM_LENGTH then
+    return
+  end
+  local r, g, b, match_end = line:sub(i):match "^rgb%(%s*(%d+%%?)%s*,%s*(%d+%%?)%s*,%s*(%d+%%?)%s*%)()"
+  if not match_end then
+    r, g, b, match_end = line:sub(i):match "^rgb%(%s*(%d+%%?)%s+(%d+%%?)%s+(%d+%%?)%s*%)()"
+    if not match_end then
+      return
+    end
+  end
+  r = percent_or_hex(r)
+  if not r then
+    return
+  end
+  g = percent_or_hex(g)
+  if not g then
+    return
+  end
+  b = percent_or_hex(b)
+  if not b then
+    return
+  end
+  local rgb_hex = string.format("%02x%02x%02x", r, g, b)
+  return match_end - 1, rgb_hex
+end
+
+local CSS_RGBA_FN_MINIMUM_LENGTH = #"rgba(0,0,0,0)" - 1
+---Parse for rgba() css function and return rgb hex.
+-- Todo consider removing the regexes here
+-- Todo this might not be the best approach to alpha channel.
+-- Things like pumblend might be useful here.
+---@param line string: Line to parse
+---@param i number: Index of line from where to start parsing
+---@return number|nil: Index of line where the rgba function ended
+---@return string|nil: rgb hex value
+function color.rgba_function_parser(line, i)
+  if #line < i + CSS_RGBA_FN_MINIMUM_LENGTH then
+    return
+  end
+  local r, g, b, a, match_end =
+    line:sub(i):match "^rgba%(%s*(%d+%%?)%s*,%s*(%d+%%?)%s*,%s*(%d+%%?)%s*,%s*([.%d]+)%s*%)()"
+  if not match_end then
+    r, g, b, a, match_end = line:sub(i):match "^rgba%(%s*(%d+%%?)%s+(%d+%%?)%s+(%d+%%?)%s+([.%d]+)%s*%)()"
+    if not match_end then
+      return
+    end
+  end
+  a = tonumber(a)
+  if not a or a > 1 then
+    return
+  end
+  r = percent_or_hex(r)
+  if not r then
+    return
+  end
+  g = percent_or_hex(g)
+  if not g then
+    return
+  end
+  b = percent_or_hex(b)
+  if not b then
+    return
+  end
+  local rgb_hex = string.format("%02x%02x%02x", r * a, g * a, b * a)
+  return match_end - 1, rgb_hex
+end
+
+---parse for #rrggbbaa and return rgb hex.
+-- a format used in android apps
+---@param line string: line to parse
+---@param i number: index of line from where to start parsing
+---@param opts table: Containing minlen, maxlen, valid_lengths
+---@return number|nil: index of line where the hex value ended
+---@return string|nil: rgb hex value
+function color.rgba_hex_parser(line, i, opts)
+  local minlen, maxlen, valid_lengths = opts.minlen, opts.maxlen, opts.valid_lengths
+  local j = i + 1
+  if #line < j + minlen - 1 then
+    return
+  end
+
+  if i > 1 and byte_is_alphanumeric(line:byte(i - 1)) then
+    return
+  end
+
+  local n = j + maxlen
+  local alpha
+  local v = 0
+
+  while j <= min(n, #line) do
+    local b = line:byte(j)
+    if not byte_is_hex(b) then
+      break
+    end
+    if j - i >= 7 then
+      alpha = parse_hex(b) + lshift(alpha or 0, 4)
+    else
+      v = parse_hex(b) + lshift(v, 4)
+    end
+    j = j + 1
+  end
+
+  if #line >= j and byte_is_alphanumeric(line:byte(j)) then
+    return
+  end
+
+  local length = j - i
+  if length ~= 4 and length ~= 7 and length ~= 9 then
+    return
+  end
+
+  if alpha then
+    alpha = tonumber(alpha) / 255
+    local r = floor(band(rshift(v, 16), 0xFF) * alpha)
+    local g = floor(band(rshift(v, 8), 0xFF) * alpha)
+    local b = floor(band(v, 0xFF) * alpha)
+    local rgb_hex = string.format("%02x%02x%02x", r, g, b)
+    return 9, rgb_hex
+  end
+  return (valid_lengths[length - 1] and length), line:sub(i + 1, i + length - 1)
+end
+
+return color