-------------------------------------------------------------------------------
-- Copyright (c) 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
-------------------------------------------------------------------------------

---
-- @module tablecompare
--
local M = {}

local function checks() end

local function pathconcat(pt, starti, endi)
  local t = {}
  local prev
  local empties = 0
  starti = starti or 1
  endi = endi or #pt

  for i = starti, endi do
    local v = pt[i]
    if not v then break
    elseif v == '' then
      empties = empties+1
    else
      table.insert(t, prev)
      prev = v
    end
  end
  table.insert(t, prev)
  return table.concat(t, '.', 1, endi-starti+1-empties)
end

--------------------------------------------------------------------------------
-- Cleans a path.
--
-- Removes trailing/preceding/doubling '.'.
--
-- @function [parent=#tablecompare] clean
-- @param path string containing the path to clean.
-- @return cleaned path as a string.
--
function M.clean(path)
  checks('string')
  local p = M.segments(path)
  return pathconcat(p)
end

--
-- @function [parent=#tablecompare] recursivePairs
-- @param t table to iterate.
-- @param prefix path prefix to prepend to the key path returned.
-- @return iterator function.
-- @usage {toto={titi=1, tutu=2}, tata = 3, tonton={4, 5}} will iterate through
-- ("toto.titi",1), ("toto.tutu",2), ("tata",3) ("tonton.1", 4), ("tonton.2"=5)
--
function M.recursivepairs(t, prefix)
  checks('table', '?string')
  local function it(t, prefix, cp)
    cp[t] = true
    local pp = prefix == "" and prefix or "."
    for k, v in pairs(t) do
      k = pp..tostring(k)
      if type(v) == 'table' then
        if not cp[v] then it(v, prefix..k, cp) end
      else
        coroutine.yield(prefix..k, v)
      end
    end
    cp[t] = nil
  end

  prefix = prefix or ""
  return coroutine.wrap(function() it(t, M.clean(prefix), {}) end)
end

--------------------------------------------------------------------------------
-- Splits a path into segments.
--
-- Each segment is delimited by '.' pattern.
--
-- @function [parent=#tablecompare] segments
-- @param path string containing the path to split.
-- @return list of split path elements.
--
function M.segments(path)
  checks('string')
  local t = {}
  local index, newindex, elt = 1
  repeat
    newindex = path:find(".", index, true) or #path+1 --last round
    elt = path:sub(index, newindex-1)
    elt = tonumber(elt) or elt
    if elt and elt ~= "" then table.insert(t, elt) end
    index = newindex+1
  until newindex==#path+1
  return t
end

---
-- @function [parent=#tablecompare] recursivepairs
-- @param t table to iterate.
-- @param prefix path prefix to prepend to the key path returned.
-- @return iterator function.
-- @usage {toto={titi=1, tutu=2}, tata = 3, tonton={4, 5}} will iterate through
-- ("toto.titi",1), ("toto.tutu",2), ("tata",3) ("tonton.1", 4), ("tonton.2"=5)
--
function M.recursivepairs(t, prefix)
  checks('table', '?string')
  local function it(t, prefix, cp)
    cp[t] = true
    local pp = prefix == "" and prefix or "."
    for k, v in pairs(t) do
      k = pp..tostring(k)
      if type(v) == 'table' then
        if not cp[v] then it(v, prefix..k, cp) end
      else
        coroutine.yield(prefix..k, v)
      end
    end
    cp[t] = nil
  end

  prefix = prefix or ""
  return coroutine.wrap(function() it(t, M.clean(prefix), {}) end)
end

function M.diff(t1, t2, norecurse)
  local d = {}
  local t3 = {}
  local rpairs = norecurse and pairs or M.recursivepairs
  for k, v in rpairs(t1) do t3[k] = v end
  for k, v in rpairs(t2) do
    if v ~= t3[k] then
      table.insert(d, k)
    end
    t3[k] = nil
  end
  for k, v in pairs(t3) do
    table.insert(d, k)
  end
  return d
end
---
-- @function [parent=#tablecompare] compare
-- @param #table t1
-- @param #table t2
--
local ignoredtypes = {
  ['function'] = true,
  ['thread']   = true,
  ['userdata'] = true,
}

function M.compare(t1, t2)

  -- Build t1 copy
  local t3 = {}
  for k,v in M.recursivepairs(t1) do
    t3[k] = v
  end

  -- Browse recursively for differences with t2
  local differences = {}
  for k, v in M.recursivepairs( t2 ) do
    local t3valuetype = type( t3[k] )
    local t2valuetype = type( v )

    -- Values are different when their type differ
    if t3valuetype ~= t2valuetype then
      table.insert(differences, k)
    elseif not ignoredtypes[t3valuetype] and v ~= t3[k] then
      -- Same type but different values
      table.insert(differences, k)
    end
    t3[k] = nil
  end

  -- Loacate t1 keys which are not in t2
  for k, v in M.recursivepairs( t3 ) do
    table.insert(differences, k)
  end
  return differences
end
---
-- @function [parent=#tablecompare] stripfunctions
-- @param #table tab Table to strip
-- @return #table Table stripped from functions
--
function M.stripfunctions(tab, visitedtables)

  -- Avoid infinite self referenced table browsing
  visitedtables = visitedtables or {}
  visitedtables[tab] = true

  for k, v in pairs( tab ) do
    local typev = type(v)
    if typev == 'function' then
      tab[k] = nil
    elseif typev == 'table' and not visitedtables[v] then
      M.stripfunctions(v, visitedtables)
    end
  end
  return tab
end
return M