--[[
Copyright (c) 2012-2013 Kaarle Ritvanen
See LICENSE file for license details
--]]

module(..., package.seeall)

local map = require('acf.util').map


function is_absolute(path)
   return string.sub(path, 1, 1) == '/'
end

function to_absolute(path, base)
   if not is_absolute(path) then
      path = base..(base ~= '/' and '/' or '')..path
   end
   local comps = split(path)
   local i = 1
   while i <= #comps do
      if comps[i] == '..' then
	 if i == 1 then error('Invalid path: '..path) end
	 table.remove(comps, i - 1)
	 table.remove(comps, i - 1)
	 i = i - 1
      else i = i + 1 end
   end
   return '/'..table.concat(comps, '/')
end


local function escape(comp)
   if type(comp) == 'number' then return tostring(comp) end
   local res = string.gsub(comp, '([\\/])', '\\%1')
   return tonumber(res) and '\\'..res or res
end


function rawjoin(p1, p2, ...)
   if not p2 then return p1 end
   if not is_absolute(p2) then p2 = '/'..p2 end
   return rawjoin((p1 == '/' and '' or p1)..p2, unpack(arg))
end

function join(parent, ...) return rawjoin(parent, unpack(map(escape, arg))) end


function split(path)
   local res = {}
   local comp = ''
   local escaped

   local function merge(s)
      if s > '' then table.insert(res, not escaped and tonumber(s) or s) end
   end

   while true do
      local prefix, sep, suffix = string.match(path, '([^\\/]*)([\\/])(.*)')
      if not prefix then
	 merge(comp..path)
	 return res
      end

      comp = comp..prefix
      if sep == '\\' then
	 comp = comp..string.sub(suffix, 1, 1)
	 escaped = true
	 path = string.sub(suffix, 2, -1)
      else
	 merge(comp)
	 comp = ''
	 escaped = false
	 path = suffix
      end
   end
end


function parent(path)
   local comps = split(path)
   table.remove(comps)
   return join('/', unpack(comps))
end

function name(path)
   local comps = split(path)
   return comps[#comps]
end