-------------------------------------------------------------------------------
-- Copyright (c) 2011-2012 Sierra Wireless and others.
-- All rights reserved. This program and the accompanying materials
-- are made available under the terms of the Eclipse Public License v1.0
-- which accompanies this distribution, and is available at
-- http://www.eclipse.org/legal/epl-v10.html
--
-- Contributors:
--     Sierra Wireless - initial API and implementation
-------------------------------------------------------------------------------
-- Platform/OS specific features and path handling.
-------------------------------------------------------------------------------

local url = require "debugger.url"
local util = require "debugger.util"

local M = { }

-- Execution plaform (could be win or unix)
-- Used to manage file path difference between the 2 platform
local platform = nil

-- keep all computed URIs in cache (as they are quite long to compute)
local uri_cache = { }

-- parse a normalized path and return a table of each segment
-- you could precise the path seperator.
local function split(path,sep)
  local t = {}
  for w in path:gmatch("[^"..(sep or "/").."]+")do
    table.insert(t, w)
  end
  return t
end

--- Returns a RFC2396 compliant URI for given source, or false if the mapping failed
local function get_abs_file_uri (source)
  local uri
  if source:sub(1,1) == "@" then -- real source file
    local sourcepath = source:sub(2)
    local normalizedpath = M.normalize(sourcepath)
    if not M.is_path_absolute(normalizedpath) then
      normalizedpath = M.normalize(M.base_dir .. "/" .. normalizedpath)
    end
    return M.to_file_uri(normalizedpath)
  else -- dynamic code, stripped bytecode, tail return, ...
    return false
  end
end

--FIXME: as result is cached, changes in package.path that modify the module name are missed
-- (mostly affect main module when Lua interpreter is launched with an absolute path)
local function get_module_uri (source)
  if source:sub(1,1) == "@" then -- real source file
    local uri
    local sourcepath = source:sub(2)
    local normalizedpath = M.normalize(sourcepath)
    local luapathtable = split (package.path, ";")
    local is_source_absolute = M.is_path_absolute(sourcepath)
    -- workarround : Add always the ?.lua entry to support
    -- the case where file was loaded by : "lua myfile.lua"
    table.insert(luapathtable,"?.lua")
    for i,var in ipairs(luapathtable) do
      -- avoid relative patterns matching absolute ones (e.g. ?.lua matches anything)
      if M.is_path_absolute(var) == is_source_absolute then
        local escaped = string.gsub(M.normalize(var),"[%^%$%(%)%%%.%[%]%*%+%-%?]",function(c) return "%"..c end)
        local pattern = string.gsub(escaped,"%%%?","(.+)")
        local modulename = string.match(normalizedpath,pattern)
        if modulename then
          modulename = string.gsub(modulename,"/",".");
          -- if we find more than 1 possible modulename return the shorter
          if not uri or string.len(uri)>string.len(modulename) then
            uri = modulename
          end
        end
      end
    end
    if uri then return "module:///"..uri end
  end
  return false
end

function M.get_uri (source)
  -- search in cache
  local uri = uri_cache[source]
  if uri ~= nil then return uri end

  -- not found, create uri
  if util.features.uri == "module" then
    uri = get_module_uri(source)
    if not uri then uri = get_abs_file_uri (source) end
  else
    uri =  get_abs_file_uri (source)
  end

  uri_cache[source] = uri
  return uri
end

-- get path file from uri
function M.get_path (uri)
  local parsed_path = assert(url.parse(uri))
  if parsed_path.scheme == "file" then
    return M.to_path(parsed_path)
  else
    -- search in cache
    -- we should surely calculate it instead of find in cache
    for k,v in pairs(uri_cache)do
      if v == uri then
        assert(k:sub(1,1) == "@")
        return k:sub(2)
      end
    end
  end
end

function M.normalize(path)
  local parts = { }
  for w in path:gmatch("[^/]+") do
    if     w == ".." and #parts ~=0 then table.remove(parts)
    elseif w ~= "."  then table.insert(parts, w)
    end
  end
  return (path:sub(1,1) == "/" and "/" or "") .. table.concat(parts, "/")
end

function M.init(executionplatform,workingdirectory)
  --------------------------
  -- define current platform
  --------------------------
  -- check parameter
  if executionplatform and executionplatform ~= "unix" and executionplatform ~="win" then
    error("Unable to initialize platform module : execution platform should be 'unix' or 'win'.")
  end

  -- use parameter as current platform
  if executionplatform then
    platform = executionplatform
  else
    --if not define try to guess it.
    local function iswindows()
      local p = io.popen("echo %os%")
      if p then
        local result =p:read("*l")
        p:close()
        return result == "Windows_NT"
      end
      return false
    end

    local status, iswin = pcall(iswindows)
    if status and iswin then
      platform = "win"
    else
      platform = "unix"
    end
  end

  --------------------------
  -- platform dependent function
  --------------------------
  if platform == "unix" then
    -- The Path separator character
    M.path_sep = "/"

    -- TODO the way to get the absolute path can be wrong if the program loads new source files by relative path after a cd.
    -- currently, the directory is registered on start, this allows program to load any source file and then change working dir,
    -- which is the most common use case.
    M.base_dir = workingdirectory or os.getenv("PWD")

    -- convert parsed URL table to file path  for the current OS (see url.parse from luasocket)
    M.to_file_uri = function (path) return url.build{scheme="file",authority="", path=path} end

    -- return true is the path is absolute
    -- the path must be normalized
    M.is_path_absolute = function (path) return path:sub(1,1) == "/" end

    -- convert absolute normalized path file to uri
    M.to_path = function (parsed_url) return url.unescape(parsed_url.path) end
  else
    -- Implementations for Windows, see UNIX versions for documentation.
    M.path_sep = "\\"
    M.is_path_absolute = function (path) return path:match("^%a:/") end
    M.to_file_uri = function (path) return url.build{scheme="file",authority="", path="/"..path} end
    M.to_path = function (parsed_url) return url.unescape(parsed_url.path):gsub("^/", "") end

    local unixnormalize = M.normalize
    M.normalize = function(path) return unixnormalize(path:gsub("\\","/"):lower()) end

    -- determine base dir
    local function getworkingdirectory()
      local p = io.popen("echo %cd%")
      if p then
        local res = p:read("*l")
        p:close()
        return M.normalize(res)
      end
    end
    M.base_dir = workingdirectory or getworkingdirectory()

  end

  if not M.base_dir then error("Unable to determine the working directory.") end
end

return M