--- Generic utilities for handling pathnames.
module("luarocks.dir", package.seeall)

separator = "/"

--- Strip the path off a path+filename.
-- @param pathname string: A path+name, such as "/a/b/c"
-- or "\a\b\c".
-- @return string: The filename without its path, such as "c".
function base_name(pathname)
   assert(type(pathname) == "string")

   local base = pathname:gsub("[/\\]*$", ""):match(".*[/\\]([^/\\]*)")
   return base or pathname
end

--- Strip the name off a path+filename.
-- @param pathname string: A path+name, such as "/a/b/c".
-- @return string: The filename without its path, such as "/a/b".
-- For entries such as "/a/b/", "/a" is returned. If there are
-- no directory separators in input, "" is returned.
function dir_name(pathname)
   assert(type(pathname) == "string")
   return (pathname:gsub("/*$", ""):match("(.*)[/]+[^/]*")) or ""
end

--- Describe a path in a cross-platform way.
-- Use this function to avoid platform-specific directory
-- separators in other modules. Removes trailing slashes from
-- each component given, to avoid repeated separators.
-- Separators inside strings are kept, to handle URLs containing
-- protocols.
-- @param ... strings representing directories
-- @return string: a string with a platform-specific representation
-- of the path.
function path(...)
   local t = {...}
   while t[1] == "" do
      table.remove(t, 1)
   end
   return (table.concat(t, "/"):gsub("([^:])/+", "%1/"):gsub("^/+", "/"):gsub("/*$", ""))
end

--- Split protocol and path from an URL or local pathname.
-- URLs should be in the "protocol://path" format.
-- For local pathnames, "file" is returned as the protocol.
-- @param url string: an URL or a local pathname.
-- @return string, string: the protocol, and the pathname without the protocol.
function split_url(url)
   assert(type(url) == "string")
   
   local protocol, pathname = url:match("^([^:]*)://(.*)")
   if not protocol then
      protocol = "file"
      pathname = url
   end
   return protocol, pathname
end

--- Normalize a url or local path.
-- URLs should be in the "protocol://path" format. System independent
-- forward slashes are used, removing trailing and double slashes
-- @param url string: an URL or a local pathname.
-- @return string: Normalized result.
function normalize(name)
   local protocol, pathname = split_url(name)
   pathname = pathname:gsub("\\", "/"):gsub("(.)/*$", "%1"):gsub("//", "/")
   if protocol ~= "file" then pathname = protocol .."://"..pathname end
   return pathname
end