local fs = require "luacheck.fs"
local utils = require "luacheck.utils"

-- Only ?, *, ** and simple character classes (with ranges and negation) are supported.
-- Hidden files are not treated specially. Special characters can't be escaped.
local globbing = {}

local function is_regular_path(glob)
   return not glob:find("[*?%[]")
end

local function get_parts(path)
   local parts = {}

   for part in path:gmatch("[^"..utils.dir_sep.."]+") do
      table.insert(parts, part)
   end

   return parts
end

local function glob_pattern_escaper(c)
   return ((c == "*" or c == "?") and "." or "%")..c
end

local function glob_range_escaper(c)
   return c == "-" and c or ("%"..c)
end

local function glob_part_to_pattern(glob_part)
   local buffer = {"^"}
   local i = 1

   while i <= #glob_part do
      local bracketless
      bracketless, i = glob_part:match("([^%[]*)()", i)
      table.insert(buffer, (bracketless:gsub("%p", glob_pattern_escaper)))

      if glob_part:sub(i, i) == "[" then
         table.insert(buffer, "[")
         i = i + 1
         local first_char = glob_part:sub(i, i)

         if first_char == "!" then
            table.insert(buffer, "^")
            i = i + 1
         elseif first_char == "]" then
            table.insert(buffer, "%]")
            i = i + 1
         end

         bracketless, i = glob_part:match("([^%]]*)()", i)

         if bracketless:sub(1, 1) == "-" then
            table.insert(buffer, "%-")
            bracketless = bracketless:sub(2)
         end

         local last_dash = ""

         if bracketless:sub(-1) == "-" then
            last_dash = "-"
            bracketless = bracketless:sub(1, -2)
         end

         table.insert(buffer, (bracketless:gsub("%p", glob_range_escaper)))
         table.insert(buffer, last_dash.."]")
         i = i + 1
      end
   end

   table.insert(buffer, "$")
   return table.concat(buffer)
end

local function part_match(glob_part, path_part)
   return utils.pmatch(path_part, glob_part_to_pattern(glob_part))
end

local function parts_match(glob_parts, glob_i, path_parts, path_i)
   local glob_part = glob_parts[glob_i]

   if not glob_part then
      -- Reached glob end, path matches the glob or its subdirectory.
      -- E.g. path "foo/bar/baz/src.lua" matches glob "foo/*/baz".
      return true
   end

   if glob_part == "**" then
      -- "**" can consume any number of path parts.
      for i = path_i, #path_parts + 1 do
         if parts_match(glob_parts, glob_i + 1, path_parts, i) then
            return true
         end
      end

      return false
   end

   local path_part = path_parts[path_i]
   return path_part and part_match(glob_part, path_part) and (
      parts_match(glob_parts, glob_i + 1, path_parts, path_i + 1))
end

-- Checks if a path matches a globbing pattern.
-- Both must be absolute.
function globbing.match(glob, path)
   if is_regular_path(glob) then
      return fs.is_subpath(glob, path)
   end

   local glob_base, path_base
   glob_base, glob = fs.split_base(glob)
   path_base, path = fs.split_base(path)

   if glob_base ~= path_base then
      return false
   end

   local glob_parts = get_parts(glob)
   local path_parts = get_parts(path)
   return parts_match(glob_parts, 1, path_parts, 1)
end

-- Checks if glob1 is less specific than glob2 and should be applied
-- first in overrides.
function globbing.compare(glob1, glob2)
   local base1, base2
   base1, glob1 = fs.split_base(glob1)
   base2, glob2 = fs.split_base(glob2)

   if base1 ~= base2 then
      return base1 < base2
   end

   local parts1 = get_parts(glob1)
   local parts2 = get_parts(glob2)

   for i = 1, math.max(#parts1, #parts2) do
      if not parts1[i] then
         return true
      elseif not parts2[i] then
         return false
      end

      if (parts1[i] == "**" or parts2[i] == "**") and parts1[i] ~= parts2[i] then
         return parts1[i] == "**"
      end

      local _, specials1 = parts1[i]:gsub("[%*%?%[]", {})
      local _, specials2 = parts2[i]:gsub("[%*%?%[]", {})

      if specials1 ~= specials2 then
         return specials1 > specials2
      end
   end

   return glob1 < glob2
end

return globbing