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

module(..., package.seeall)

require 'stringy'

local function filter(func, tbl)
   local res = {}
   for k, v in pairs(tbl) do if func(v) then res[k] = v end end
   return res
end


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

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

function split(path)
   -- assume absolute paths
   assert(is_absolute(path))
   if path == '/' then return {} end
   return filter(function(s) return s > '' end,
		 stringy.split(string.sub(path, 2, -1), '/'))
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