local Shared = ...
local Msg = Shared.Msg
local ffi = require "ffi"
local C = ffi.C
local F = far.Flags
local PPIF_SELECTED = F.PPIF_SELECTED
local FILE_ATTRIBUTE_DIRECTORY = 0x00000010
local MCODE_F_SETCUSTOMSORTMODE = 0x80C67
local band, bor = bit.band, bit.bor -- 32 bits, be careful
local tonumber = tonumber

local CustomSortModes = {} -- key=integer, value=table
local CanChangeSortMode = true

-- shellsort [ http://lua-users.org/wiki/LuaSorting ]
-- Written by Rici Lake. The author disclaims all copyright and offers no warranty.
-- For convenience, shellsort returns its first argument.

local incs = { 1391376,
               463792, 198768, 86961, 33936,
               13776, 4592, 1968, 861, 336,
               112, 48, 21, 7, 3, 1 }

local function shellsort(t, n, before)
  for _, h in ipairs(incs) do
    for i = h, n - 1 do
      local v = t[i]
      for j = i - h, 0, -h do
        local testval = t[j]
        if not before(v, testval) then break end
        t[i] = testval
        i = j
      end
      t[i] = v
    end
  end
  return t
end

-- qsort [ extracted from Lua 5.1 distribution (file /test/sort.lua) ]
local function qsort(x,l,u,f)

  local function recurse(l,u)
    if l<u then
      local m=math.random(u-(l-1))+l-1 -- choose a random pivot in range l..u
      x[l],x[m] = x[m],x[l] -- swap pivot to first position
      local t = x[l]        -- pivot value
      m = l
      for i=l+1, u do
        -- invariant: x[l+1..m] < t <= x[m+1..i-1]
        if f(x[i], t) then
          m = m+1
          x[m],x[i] = x[i],x[m]  -- swap x[i] and x[m]
        end
      end
      x[l],x[m] = x[m],x[l]      -- swap pivot to a valid place
      -- x[l+1..m-1] < x[m] <= x[m+1..u]
      recurse(l, m-1)
      recurse(m+1, u)
    end
  end

  recurse(l,u)
end

local BooleanProperties = {
  "InvertByDefault", "NoSortEqualsByName"
}
local TernaryProperties = {
  "DirectoriesFirst", "SelectedFirst", "RevertSorting", "SortGroups"
}

local function LoadCustomSortMode (nMode, Settings)
  assert(type(nMode)=="number" and nMode==math.floor(nMode) and nMode>=100 and nMode<=0x7FFFFFFF)
  if type(Settings) == "table" then
    local t = {}

    if type(Settings.Compare) == "function" then t.Compare=Settings.Compare end
    local cond = Settings.Condition or Settings.condition -- allow lower case for 'Condition'
    if type(cond) == "function" then t.Condition=cond end
    if not (t.Compare or t.Condition) then
      CustomSortModes[nMode] = nil
      return
    end

    if type(Settings.InitSort)     == "function" then t.InitSort=Settings.InitSort end
    if type(Settings.EndSort)      == "function" then t.EndSort=Settings.EndSort end
    if type(Settings.SortFunction) == "string"   then t.SortFunction=Settings.SortFunction end
    if type(Settings.Description)  == "string"   then t.Description=Settings.Description end

    if type(Settings.Indicator) == "string" then t.Indicator=(Settings.Indicator.."  "):sub(1,2)
    else t.Indicator = "  "
    end

    for _,v in ipairs(BooleanProperties) do t[v] = not not Settings[v] end
    for _,v in ipairs(TernaryProperties) do t[v] = Settings[v]==0 and 0 or Settings[v]==1 and 1 or 2 end

    CustomSortModes[nMode] = t
  else
    CustomSortModes[nMode] = nil
  end
end

local function CanDoPanelSort (SortMode)
  local tSettings = CustomSortModes[SortMode]
  if tSettings then
    if tSettings.Condition then
      CanChangeSortMode = false
      local ok, ret = pcall(tSettings.Condition, SortMode)
      CanChangeSortMode = true
      if not ok then Shared.ErrMsg(ret); return; end
      if not ret then return; end
      tSettings = CustomSortModes[SortMode] -- retrieve again as it may be reloaded by Condition()
      return tSettings and tSettings.Compare and true
    else
      return true
    end
  end
end

local function SetCustomSortMode (nMode, whatpanel, order)
  if CanChangeSortMode then
    if CanDoPanelSort(nMode) then
      if     order=="auto"    then order=0
      elseif order=="current" then order=1
      elseif order=="direct"  then order=2
      elseif order=="reverse" then order=3
      else order = 0
      end
      local Settings = CustomSortModes[nMode]
      whatpanel = whatpanel==1 and 1 or 0
      Shared.MacroCallFar(MCODE_F_SETCUSTOMSORTMODE, whatpanel, nMode, Settings.InvertByDefault, order)
    end
  end
end

local function CustomSortMenu()
  local Id = win.Uuid("C323FBCF-6803-4F2C-B8B4-E576E7F125DC")
  local items, bkeys = {}, {
    { BreakKey="C+RETURN",    order="auto" },
    { BreakKey="CS+RETURN",   order="auto" },
    { BreakKey="ADD",         order="direct" },
    { BreakKey="C+ADD",       order="direct" },
    { BreakKey="CS+ADD",      order="direct" },
    { BreakKey="SUBTRACT",    order="reverse" },
    { BreakKey="C+SUBTRACT",  order="reverse" },
    { BreakKey="CS+SUBTRACT", order="reverse" },
  }
  local pinfo = panel.GetPanelInfo(nil,1)
  for k,v in pairs(CustomSortModes) do
    local item = { text=v.Description and tostring(v.Description) or Msg.PSDefaultMenuItemText..k; Mode=k; }
    if pinfo.SortMode == k then
      item.selected = true
      item.checked = band(pinfo.Flags,F.PFLAGS_REVERSESORTORDER)==0 and "+" or "-"
    end
    items[#items+1] = item
  end
  table.sort(items, function(a,b) return a.Mode < b.Mode end)
  local r, pos = far.Menu({Title=Msg.PSMenuTitle, Id=Id}, items, bkeys)
  if r and (pos > 0) then
    local apanel = not r.BreakKey or r.BreakKey:find("^CS%+") or not r.BreakKey:find("%+")
    local ppanel = r.BreakKey and r.BreakKey:find("^CS?%+")
    if ppanel then SetCustomSortMode(items[pos].Mode, 1, r.order) end
    if apanel then SetCustomSortMode(items[pos].Mode, 0, r.order) end
  end
end

local function GetSortModes()
  local t = {}
  for mode in pairs(CustomSortModes) do
    t[#t+1]=mode; t[#t+1]=mode; t[#t+1]=mode;
  end
  table.sort(t)
  for k=1,#t,3 do
    local mode = t[k]
    t[k+1] = CustomSortModes[mode].InvertByDefault
    t[k+2] = CustomSortModes[mode].Description or Msg.PSDefaultMenuItemText..mode
  end
  t.n = #t
  return t
end

ffi.cdef[[
  typedef struct
  {
    unsigned int               *Positions;
    void                       *Items;
    size_t                      ItemsCount;
    void                      (*FileListToPluginItem)(const void*, int, struct SortingPanelItem*);
    int                         SortGroups;
    int                         SelectedFirst;
    int                         DirectoriesFirst;
    int                         SortMode;
    int                         RevertSorting;
    int                         NumericSort;
    int                         CaseSensitiveSort;
    HANDLE                      hSortPlugin;
  } CustomSort;
]]

-- local function Utf16Buf (str)
--   str = win.Utf8ToUtf16(str)
--   local buf = ffi.new("wchar_t[?]", #str/2+1)
--   ffi.copy(buf, str, #str)
--   return buf
-- end

-- local function wcscmp(p1,p2)
--   local pos = 0
--   while p1[pos] == p2[pos] do
--     if p1[pos] == 0 then return 0 end
--     pos = pos + 1
--   end
--   return p1[pos] - p2[pos]
-- end

local function IsTwoDots(p) return p[0]==46 and p[1]==46 and p[2]==0 end
local function Empty(p) return p[0]==0 end

-- called from Far
local function SortPanelItems (params)
  jit.flush()
  params = ffi.cast("CustomSort*", params)
  local tSettings = CustomSortModes[tonumber(params.SortMode)]
  if not (tSettings and tSettings.Compare) then return end

  local Compare = tSettings.Compare
  local SortEqualsByName = not tSettings.NoSortEqualsByName

  local pi1 = ffi.new("struct SortingPanelItem")
  local pi2 = ffi.new("struct SortingPanelItem")

  local SortGroups, SelectedFirst, DirectoriesFirst, RevertSorting

  if tSettings.SortGroups==0 then SortGroups=false
  elseif tSettings.SortGroups==1 then SortGroups=true
  else SortGroups = params.SortGroups ~= 0
  end

  if tSettings.SelectedFirst==0 then SelectedFirst=false
  elseif tSettings.SelectedFirst==1 then SelectedFirst=true
  else SelectedFirst = params.SelectedFirst ~= 0
  end

  if tSettings.DirectoriesFirst==0 then DirectoriesFirst=false
  elseif tSettings.DirectoriesFirst==1 then DirectoriesFirst=true
  else DirectoriesFirst = params.DirectoriesFirst ~= 0
  end

  if tSettings.RevertSorting==0 then RevertSorting=false
  elseif tSettings.RevertSorting==1 then RevertSorting=true
  else RevertSorting = params.RevertSorting ~= 0
  end

  local outParams = {
    SortGroups        = params.SortGroups ~= 0;
    SelectedFirst     = params.SelectedFirst ~= 0;
    DirectoriesFirst  = params.DirectoriesFirst ~= 0;
    RevertSorting     = params.RevertSorting ~= 0;
    NumericSort       = params.NumericSort ~= 0;
    CaseSensitiveSort = params.CaseSensitiveSort ~= 0;
  }

  local function Before(n1, n2)
    params.FileListToPluginItem(params.Items, n1, pi1)
    params.FileListToPluginItem(params.Items, n2, pi2)
    ----------------------------------------------------------------------------
    -- TODO: fix in Far
    if IsTwoDots(pi1.FileName) then
      if not IsTwoDots(pi2.FileName) then return true end

      if Empty(pi1.AlternateFileName) or IsTwoDots(pi1.AlternateFileName) then
        if not (Empty(pi2.AlternateFileName) or IsTwoDots(pi2.AlternateFileName)) then return true end
      else
        if Empty(pi2.AlternateFileName) or IsTwoDots(pi2.AlternateFileName) then return false end
      end

    elseif IsTwoDots(pi2.FileName) then
      return false
    end
    ----------------------------------------------------------------------------
    if DirectoriesFirst then
      local a1,a2 = band(tonumber(pi1.FileAttributes), FILE_ATTRIBUTE_DIRECTORY),
                    band(tonumber(pi2.FileAttributes), FILE_ATTRIBUTE_DIRECTORY)
      if a1 ~= a2 then return a1 > a2 end
    end
    ----------------------------------------------------------------------------
    if SelectedFirst then
      local s1,s2 = band(tonumber(pi1.Flags),PPIF_SELECTED), band(tonumber(pi2.Flags),PPIF_SELECTED)
      if s1 ~= s2 then return s1 > s2 end
    end
    ----------------------------------------------------------------------------
    if SortGroups then
      if pi1.SortGroup ~= pi2.SortGroup then return pi1.SortGroup < pi2.SortGroup end
    end
    ----------------------------------------------------------------------------
    local r = Compare(pi1, pi2, outParams)
    if r ~= 0 then
      if RevertSorting then r = -r end
      return r < 0
    else
      if SortEqualsByName then
        return 1 == C.CompareStringW(C.LOCALE_USER_DEFAULT, bor(C.NORM_IGNORECASE,C.SORT_STRINGSORT),
                                     pi1.FileName, -1, pi2.FileName, -1)
      end
    end
    return false
  end

  if tSettings.InitSort then tSettings.InitSort(outParams) end

  if tSettings.SortFunction == "qsort" then
    qsort(params.Positions, 0, tonumber(params.ItemsCount)-1, Before)
  else -- default
    shellsort(params.Positions, tonumber(params.ItemsCount), Before)
  end

  if tSettings.EndSort then tSettings.EndSort() end

  return tSettings.Indicator
end

return {
  SortPanelItems=SortPanelItems,
  LoadCustomSortMode=LoadCustomSortMode,
  SetCustomSortMode=SetCustomSortMode,
  CustomSortMenu=CustomSortMenu,
  GetSortModes=GetSortModes,
  DeleteSortModes=function() CustomSortModes={} end,
  CanDoPanelSort=CanDoPanelSort,
}