////////////////////////////////////////////////////////////////////////////////
// Taskwarrior Lua API
//
// Copyright 2006 - 2011, Paul Beckingham, Federico Hernandez.
// All rights reserved.
//
// This program is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free Software
// Foundation; either version 2 of the License, or (at your option) any later
// version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
// details.
//
// You should have received a copy of the GNU General Public License along with
// this program; if not, write to the
//
//     Free Software Foundation, Inc.,
//     51 Franklin Street, Fifth Floor,
//     Boston, MA
//     02110-1301
//     USA
//
// -------------
//
// Copyright © 1994–2008 Lua.org, PUC-Rio.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
////////////////////////////////////////////////////////////////////////////////

#include <algorithm>
#include <iostream>
#include <Context.h>
#include <API.h>

extern Context context;
Task* the_task = NULL;

#ifdef HAVE_LIBLUA

////////////////////////////////////////////////////////////////////////////////
// Returns a string representing the taskwarrior version number, such as
// '1.9.0'.
static int api_task_version (lua_State* L)
{
  lua_pushstring (L, PACKAGE_VERSION);
  return 1;
}

////////////////////////////////////////////////////////////////////////////////
// Returns a string representing the Lua version number, such as '5.1.4'.
// Lua 5.2.0 has a 'lua_version' call, but 5.1.4 is the target.
static int api_task_lua_version (lua_State* L)
{
  // Convert "Lua 5.1.4" -> "5.1.4"
  std::string ver = LUA_RELEASE;
  lua_pushstring (L, ver.substr (4, std::string::npos).c_str ());
  return 1;
}

////////////////////////////////////////////////////////////////////////////////
// Returns the type of OS that task is running on.
static int api_task_os (lua_State* L)
{
#if defined (DARWIN)
  lua_pushstring (L, "darwin");
#elif defined (SOLARIS)
  lua_pushstring (L, "solaris");
#elif defined (CYGWIN)
  lua_pushstring (L, "cygwin");
#elif defined (OPENBSD)
  lua_pushstring (L, "openbsd");
#elif defined (HAIKU)
  lua_pushstring (L, "haiku");
#elif defined (FREEBSD)
  lua_pushstring (L, "freebsd");
#elif defined (LINUX)
  lua_pushstring (L, "linux");
#else
  lua_pushstring (L, "unknown");
#endif

  return 1;
}

////////////////////////////////////////////////////////////////////////////////
static int api_task_feature (lua_State* L)
{
  std::string name = luaL_checkstring (L, 1);
  bool value = false;

  if (name == "readline")
  {
#ifdef HAVE_READLINE
    value = true;
#endif
  }

  else if (name == "lua")
    value = true;

  lua_pushboolean (L, value ? 1 : 0);
  return 1;
}

////////////////////////////////////////////////////////////////////////////////
static int api_task_header_message (lua_State* L)
{
  std::string message = luaL_checkstring (L, 1);
  context.header (message);
  return 0;
}

////////////////////////////////////////////////////////////////////////////////
static int api_task_footnote_message (lua_State* L)
{
  std::string message = luaL_checkstring (L, 1);
  context.footnote (message);
  return 0;
}

////////////////////////////////////////////////////////////////////////////////
static int api_task_debug_message (lua_State* L)
{
  std::string message = luaL_checkstring (L, 1);
  context.debug (message);
  return 0;
}

////////////////////////////////////////////////////////////////////////////////
// Causes the shell or interactive mode task to exit.  Ordinarily this does not
// occur.
static int api_task_exit (lua_State* L)
{
  // TODO Is this the correct exception?  How does the shell handle this?
  std::cout << "Exiting." << std::endl;
  exit (0); 
  return 0;
}

////////////////////////////////////////////////////////////////////////////////
API::API ()
: L (NULL)
{
}

////////////////////////////////////////////////////////////////////////////////
API::~API ()
{
  if (L)
  {
    lua_close (L);
    L = NULL;
  }
}

////////////////////////////////////////////////////////////////////////////////
void API::initialize ()
{
  // Initialize Lua.
  L = lua_open ();
  luaL_openlibs (L);  // TODO Error handling

  // Register all the API functions in Lua global space.
  lua_pushcfunction (L, api_task_version);               lua_setglobal (L, "task_version");
  lua_pushcfunction (L, api_task_lua_version);           lua_setglobal (L, "task_lua_version");
  lua_pushcfunction (L, api_task_os);                    lua_setglobal (L, "task_os");
  lua_pushcfunction (L, api_task_feature);               lua_setglobal (L, "task_feature");
  lua_pushcfunction (L, api_task_header_message);        lua_setglobal (L, "task_header_message");
  lua_pushcfunction (L, api_task_footnote_message);      lua_setglobal (L, "task_footnote_message");
  lua_pushcfunction (L, api_task_debug_message);         lua_setglobal (L, "task_debug_message");
  lua_pushcfunction (L, api_task_exit);                  lua_setglobal (L, "task_exit");
}

////////////////////////////////////////////////////////////////////////////////
bool API::callProgramHook (
  const std::string& file,
  const std::string& function)
{
  loadFile (file);

  // Get function.
  lua_getglobal (L, function.c_str ());
  if (!lua_isfunction (L, -1))
  {
    lua_pop (L, 1);
    throw std::string ("The Lua function '") + function + "' was not found.";
  }

  // Make call.
  if (lua_pcall (L, 0, 2, 0) != 0)
    throw std::string ("Error calling '") + function + "' - " + lua_tostring (L, -1) + ".";

  // Call successful - get return values.
  if (!lua_isnumber (L, -2))
    throw std::string ("Error: '") + function + "' did not return a success indicator.";

  if (!lua_isstring (L, -1) && !lua_isnil (L, -1))
    throw std::string ("Error: '") + function + "' did not return a message or nil.";

  int rc              = lua_tointeger (L, -2);
  const char* message = lua_tostring  (L, -1);

  if (rc == 0)
  {
    if (message)
      context.footnote (std::string ("Warning: ") + message);
  }
  else
  {
    if (message)
      throw std::string (message);
  }

  lua_pop (L, 1);
  return rc == 0 ? true : false;
}

////////////////////////////////////////////////////////////////////////////////
bool API::callTaskHook (
  const std::string& file,
  const std::string& function,
  Task& task)
{
  loadFile (file);

  // Save the task for reference via the API.
  current = task;

  // Get function.
  lua_getglobal (L, function.c_str ());
  if (!lua_isfunction (L, -1))
  {
    lua_pop (L, 1);
    throw std::string ("The Lua function '") + function + "' was not found.";
  }

  // Prepare args.
  lua_pushnumber (L, current.id);

  // Expose the task.
  the_task = &current;

  // Make call.
  if (lua_pcall (L, 1, 2, 0) != 0)
    throw std::string ("Error calling '") + function + "' - " + lua_tostring (L, -1) + ".";

  // Hide the task.
  the_task = NULL;

  // Call successful - get return values.
  if (!lua_isnumber (L, -2))
    throw std::string ("Error: '") + function + "' did not return a success indicator.";

  if (!lua_isstring (L, -1) && !lua_isnil (L, -1))
    throw std::string ("Error: '") + function + "' did not return a message or nil.";

  int rc              = lua_tointeger (L, -2);
  const char* message = lua_tostring  (L, -1);

  if (rc == 0)
  {
    if (message)
      context.footnote (std::string ("Warning: ") + message);
  }
  else
  {
    if (message)
      throw std::string (message);
  }

  lua_pop (L, 1);
  return rc == 0 ? true : false;
}

////////////////////////////////////////////////////////////////////////////////
bool API::callFieldHook (
  const std::string& file,
  const std::string& function,
  const std::string& name,
  std::string& value)
{
  loadFile (file);

  // Get function.
  lua_getglobal (L, function.c_str ());
  if (!lua_isfunction (L, -1))
  {
    lua_pop (L, 1);
    throw std::string ("The Lua function '") + function + "' was not found.";
  }

  // Prepare args.
  lua_pushstring (L, name.c_str ());
  lua_pushstring (L, value.c_str ());

  // Make call.
  if (lua_pcall (L, 2, 3, 0) != 0)
    throw std::string ("Error calling '") + function + "' - " + lua_tostring (L, -1) + ".";

  // Call successful - get return values.
  if (!lua_isstring (L, -3))
    throw std::string ("Error: '") + function + "' did not return a modified value.";

  if (!lua_isnumber (L, -2))
    throw std::string ("Error: '") + function + "' did not return a success indicator.";

  if (!lua_isstring (L, -1) && !lua_isnil (L, -1))
    throw std::string ("Error: '") + function + "' did not return a message or nil.";

  const char* new_value = lua_tostring  (L, -3);
  int rc                = lua_tointeger (L, -2);
  const char* message   = lua_tostring  (L, -1);

  if (rc == 0)
  {
    // Overwrite with the modified value.
    value = new_value;

    if (message)
      context.footnote (std::string ("Warning: ") + message);
  }
  else
  {
    if (message)
      throw std::string (message);
  }

  lua_pop (L, 1);
  return rc == 0 ? true : false;
}

////////////////////////////////////////////////////////////////////////////////
void API::loadFile (const std::string& file)
{
  // If the file is not loaded.
  if (std::find (loaded.begin (), loaded.end (), file) == loaded.end ())
  {
    // Load the file, if possible.
    if (luaL_loadfile (L, file.c_str ()) || lua_pcall (L, 0, 0, 0))
      throw std::string ("Error: ") + std::string (lua_tostring (L, -1));

    // Mark this as loaded, so as to not bother again.
    loaded.push_back (file);
  }
}

////////////////////////////////////////////////////////////////////////////////

#endif