--[[
  The following License applies to all files within the jumper directory.

  Note that this is only a partial copy of the full jumper code base. Also,
  the code was modified to support 3D maps.
--]]

--[[
This work is under MIT-LICENSE
Copyright (c) 2012-2013 Roland Yonaba.

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.
--]]

--- The Pathfinder class

--
-- Implementation of the `pathfinder` class.

local _VERSION = ""
local _RELEASEDATE = ""

if (...) then

  -- Dependencies
  local _PATH = (...):gsub('%.pathfinder$','')
	local Utils     = require (_PATH .. '.core.utils')
	local Assert    = require (_PATH .. '.core.assert')
  local Heap      = require (_PATH .. '.core.bheap')
  local Heuristic = require (_PATH .. '.core.heuristics')
  local Grid      = require (_PATH .. '.grid')
  local Path      = require (_PATH .. '.core.path')

  -- Internalization
  local t_insert, t_remove = table.insert, table.remove
	local floor = math.floor
  local pairs = pairs
  local assert = assert
	local type = type
  local setmetatable, getmetatable = setmetatable, getmetatable

	--- Finders (search algorithms implemented). Refers to the search algorithms actually implemented in Jumper.
	--
	-- <li>[A*](http://en.wikipedia.org/wiki/A*_search_algorithm)</li>
	-- <li>[Dijkstra](http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm)</li>
	-- <li>[Theta Astar](http://aigamedev.com/open/tutorials/theta-star-any-angle-paths/)</li>
	-- <li>[BFS](http://en.wikipedia.org/wiki/Breadth-first_search)</li>
	-- <li>[DFS](http://en.wikipedia.org/wiki/Depth-first_search)</li>
	-- <li>[JPS](http://harablog.wordpress.com/2011/09/07/jump-point-search/)</li>
	-- @finder Finders
	-- @see Pathfinder:getFinders
  local Finders = {
    ['ASTAR']     = require (_PATH .. '.search.astar'),
--    ['DIJKSTRA']  = require (_PATH .. '.search.dijkstra'),
--    ['THETASTAR'] = require (_PATH .. '.search.thetastar'),
    ['BFS']       = require (_PATH .. '.search.bfs'),
--    ['DFS']       = require (_PATH .. '.search.dfs'),
--    ['JPS']       = require (_PATH .. '.search.jps')
  }

  -- Will keep track of all nodes expanded during the search
  -- to easily reset their properties for the next pathfinding call
  local toClear = {}

	--- Search modes. Refers to the search modes. In ORTHOGONAL mode, 4-directions are only possible when moving,
	-- including North, East, West, South. In DIAGONAL mode, 8-directions are possible when moving,
	-- including North, East, West, South and adjacent directions.
	--
	-- <li>ORTHOGONAL</li>
	-- <li>DIAGONAL</li>
	-- @mode Modes
	-- @see Pathfinder:getModes
  local searchModes = {['DIAGONAL'] = true, ['ORTHOGONAL'] = true}

  -- Performs a traceback from the goal node to the start node
  -- Only happens when the path was found

	--- The `Pathfinder` class.<br/>
	-- This class is callable.
	-- Therefore,_ <code>Pathfinder(...)</code> _acts as a shortcut to_ <code>Pathfinder:new(...)</code>.
	-- @type Pathfinder
  local Pathfinder = {}
  Pathfinder.__index = Pathfinder

  --- Inits a new `pathfinder`
  -- @class function
  -- @tparam grid grid a `grid`
  -- @tparam[opt] string finderName the name of the `Finder` (search algorithm) to be used for search.
	-- Defaults to `ASTAR` when not given (see @{Pathfinder:getFinders}).
  -- @tparam[optchain] string|int|func walkable the value for __walkable__ nodes.
  -- If this parameter is a function, it should be prototyped as __f(value)__, returning a boolean:
  -- __true__ when value matches a __walkable__ `node`, __false__ otherwise.
  -- @treturn pathfinder a new `pathfinder` instance
	-- @usage
	-- -- Example one
	-- local finder = Pathfinder:new(myGrid, 'ASTAR', 0)
	--
	-- -- Example two
	-- local function walkable(value)
	--   return value > 0
	-- end
	-- local finder = Pathfinder(myGrid, 'JPS', walkable)
  function Pathfinder:new(grid, finderName, walkable)
    local newPathfinder = {}
    setmetatable(newPathfinder, Pathfinder)
	  --newPathfinder:setGrid(grid)
    newPathfinder:setFinder(finderName)
    --newPathfinder:setWalkable(walkable)
    newPathfinder:setMode('DIAGONAL')
    newPathfinder:setHeuristic('MANHATTAN')
    newPathfinder:setTunnelling(false)
    return newPathfinder
  end

	--- Evaluates [clearance](http://aigamedev.com/open/tutorial/clearance-based-pathfinding/#TheTrueClearanceMetric)
	-- for the whole `grid`. It should be called only once, unless the collision map or the
	-- __walkable__ attribute changes. The clearance values are calculated and cached within the grid nodes.
  -- @class function
	-- @treturn pathfinder self (the calling `pathfinder` itself, can be chained)
	-- @usage myFinder:annotateGrid()
	function Pathfinder:annotateGrid()
		assert(self._walkable, 'Finder must implement a walkable value')
		for x=self._grid._max_x,self._grid._min_x,-1 do
			for y=self._grid._max_y,self._grid._min_y,-1 do
				local node = self._grid:getNodeAt(x,y)
				if self._grid:isWalkableAt(x,y,self._walkable) then
					local nr = self._grid:getNodeAt(node._x+1, node._y)
					local nrd = self._grid:getNodeAt(node._x+1, node._y+1)
					local nd = self._grid:getNodeAt(node._x, node._y+1)
					if nr and nrd and nd then
						local m = nrd._clearance[self._walkable] or 0
						m = (nd._clearance[self._walkable] or 0)<m and (nd._clearance[self._walkable] or 0) or m
						m = (nr._clearance[self._walkable] or 0)<m and (nr._clearance[self._walkable] or 0) or m
						node._clearance[self._walkable] = m+1
					else
						node._clearance[self._walkable] = 1
					end
				else node._clearance[self._walkable] = 0
				end
			end
		end
		self._grid._isAnnotated[self._walkable] = true
		return self
	end

	--- Removes [clearance](http://aigamedev.com/open/tutorial/clearance-based-pathfinding/#TheTrueClearanceMetric)values.
	-- Clears cached clearance values for the current __walkable__.
  -- @class function
	-- @treturn pathfinder self (the calling `pathfinder` itself, can be chained)
	-- @usage myFinder:clearAnnotations()
	function Pathfinder:clearAnnotations()
		assert(self._walkable, 'Finder must implement a walkable value')
		for node in self._grid:iter() do
			node:removeClearance(self._walkable)
		end
		self._grid._isAnnotated[self._walkable] = false
		return self
	end

  --- Sets the `grid`. Defines the given `grid` as the one on which the `pathfinder` will perform the search.
  -- @class function
  -- @tparam grid grid a `grid`
	-- @treturn pathfinder self (the calling `pathfinder` itself, can be chained)
	-- @usage myFinder:setGrid(myGrid)
  function Pathfinder:setGrid(grid)
    assert(Assert.inherits(grid, Grid), 'Wrong argument #1. Expected a \'grid\' object')
    self._grid = grid
    self._grid._eval = self._walkable and type(self._walkable) == 'function'
    return self
  end

  --- Returns the `grid`. This is a reference to the actual `grid` used by the `pathfinder`.
  -- @class function
  -- @treturn grid the `grid`
	-- @usage local myGrid = myFinder:getGrid()
  function Pathfinder:getGrid()
    return self._grid
  end

  --- Sets the __walkable__ value or function.
  -- @class function
  -- @tparam string|int|func walkable the value for walkable nodes.
	-- @treturn pathfinder self (the calling `pathfinder` itself, can be chained)
	-- @usage
	-- -- Value '0' is walkable
	-- myFinder:setWalkable(0)
	--
	-- -- Any value greater than 0 is walkable
	-- myFinder:setWalkable(function(n)
	--   return n>0
	-- end
  function Pathfinder:setWalkable(walkable)
    assert(Assert.matchType(walkable,'stringintfunctionnil'),
      ('Wrong argument #1. Expected \'string\', \'number\' or \'function\', got %s.'):format(type(walkable)))
    self._walkable = walkable
    self._grid._eval = type(self._walkable) == 'function'
    return self
  end

  --- Gets the __walkable__ value or function.
  -- @class function
  -- @treturn string|int|func the `walkable` value or function
	-- @usage local walkable = myFinder:getWalkable()
  function Pathfinder:getWalkable()
    return self._walkable
  end

  --- Defines the `finder`. It refers to the search algorithm used by the `pathfinder`.
  -- Default finder is `ASTAR`. Use @{Pathfinder:getFinders} to get the list of available finders.
  -- @class function
  -- @tparam string finderName the name of the `finder` to be used for further searches.
	-- @treturn pathfinder self (the calling `pathfinder` itself, can be chained)
	-- @usage
	-- --To use Breadth-First-Search
	-- myFinder:setFinder('BFS')
	-- @see Pathfinder:getFinders
  function Pathfinder:setFinder(finderName)
		if not finderName then
			if not self._finder then
				finderName = 'ASTAR'
			else return
			end
		end
    assert(Finders[finderName],'Not a valid finder name!')
    self._finder = finderName
    return self
  end

  --- Returns the name of the `finder` being used.
  -- @class function
  -- @treturn string the name of the `finder` to be used for further searches.
	-- @usage local finderName = myFinder:getFinder()
  function Pathfinder:getFinder()
    return self._finder
  end

  --- Returns the list of all available finders names.
  -- @class function
  -- @treturn {string,...} array of built-in finders names.
	-- @usage
	-- local finders = myFinder:getFinders()
	-- for i, finderName in ipairs(finders) do
	--   print(i, finderName)
	-- end
  function Pathfinder:getFinders()
    return Utils.getKeys(Finders)
  end

  --- Sets a heuristic. This is a function internally used by the `pathfinder` to find the optimal path during a search.
  -- Use @{Pathfinder:getHeuristics} to get the list of all available `heuristics`. One can also define
  -- his own `heuristic` function.
  -- @class function
  -- @tparam func|string heuristic `heuristic` function, prototyped as __f(dx,dy)__ or as a `string`.
	-- @treturn pathfinder self (the calling `pathfinder` itself, can be chained)
  -- @see Pathfinder:getHeuristics
	-- @see core.heuristics
	-- @usage myFinder:setHeuristic('MANHATTAN')
  function Pathfinder:setHeuristic(heuristic)
    assert(Heuristic[heuristic] or (type(heuristic) == 'function'),'Not a valid heuristic!')
    self._heuristic = Heuristic[heuristic] or heuristic
    return self
  end

  --- Returns the `heuristic` used. Returns the function itself.
  -- @class function
  -- @treturn func the `heuristic` function being used by the `pathfinder`
	-- @see core.heuristics
	-- @usage local h = myFinder:getHeuristic()
  function Pathfinder:getHeuristic()
    return self._heuristic
  end

  --- Gets the list of all available `heuristics`.
  -- @class function
  -- @treturn {string,...} array of heuristic names.
	-- @see core.heuristics
	-- @usage
	-- local heur = myFinder:getHeuristic()
	-- for i, heuristicName in ipairs(heur) do
	--   ...
	-- end
  function Pathfinder:getHeuristics()
    return Utils.getKeys(Heuristic)
  end

  --- Defines the search `mode`.
  -- The default search mode is the `DIAGONAL` mode, which implies 8-possible directions when moving (north, south, east, west and diagonals).
  -- In `ORTHOGONAL` mode, only 4-directions are allowed (north, south, east and west).
  -- Use @{Pathfinder:getModes} to get the list of all available search modes.
  -- @class function
  -- @tparam string mode the new search `mode`.
	-- @treturn pathfinder self (the calling `pathfinder` itself, can be chained)
  -- @see Pathfinder:getModes
	-- @see Modes
	-- @usage myFinder:setMode('ORTHOGONAL')
  function Pathfinder:setMode(mode)
    assert(searchModes[mode],'Invalid mode')
    self._allowDiagonal = (mode == 'DIAGONAL')
    return self
  end

  --- Returns the search mode.
  -- @class function
  -- @treturn string the current search mode
	-- @see Modes
	-- @usage local mode = myFinder:getMode()
  function Pathfinder:getMode()
    return (self._allowDiagonal and 'DIAGONAL' or 'ORTHOGONAL')
  end

  --- Gets the list of all available search modes.
  -- @class function
  -- @treturn {string,...} array of search modes.
	-- @see Modes
	-- @usage local modes = myFinder:getModes()
	-- for modeName in ipairs(modes) do
	--   ...
	-- end
  function Pathfinder:getModes()
    return Utils.getKeys(searchModes)
  end

  --- Enables tunnelling. Defines the ability for the `pathfinder` to tunnel through walls when heading diagonally.
	-- This feature __is not compatible__ with Jump Point Search algorithm (i.e. enabling it will not affect Jump Point Search)
  -- @class function
  -- @tparam bool bool a boolean
	-- @treturn pathfinder self (the calling `pathfinder` itself, can be chained)
	-- @usage myFinder:setTunnelling(true)
  function Pathfinder:setTunnelling(bool)
    assert(Assert.isBool(bool), ('Wrong argument #1. Expected boolean, got %s'):format(type(bool)))
		self._tunnel = bool
		return self
  end

  --- Returns tunnelling feature state.
  -- @class function
	-- @treturn bool tunnelling feature actual state
	-- @usage local isTunnellingEnabled = myFinder:getTunnelling()
  function Pathfinder:getTunnelling()
		return self._tunnel
  end

  --- Calculates a `path`. Returns the `path` from location __[startX, startY]__ to location __[endX, endY]__.
  -- Both locations must exist on the collision map. The starting location can be unwalkable.
  -- @class function
  -- @tparam int startX the x-coordinate for the starting location
  -- @tparam int startY the y-coordinate for the starting location
  -- @tparam int endX the x-coordinate for the goal location
  -- @tparam int endY the y-coordinate for the goal location
  -- @tparam int clearance the amount of clearance (i.e the pathing agent size) to consider
  -- @treturn path a path (array of nodes) when found, otherwise nil
	-- @usage local path = myFinder:getPath(1,1,5,5)
  function Pathfinder:getPath(startX, startY, startZ, ih, endX, endY, endZ, oh, clearance)

		self:reset()
    local startNode = self._grid:getNodeAt(startX, startY, startZ)
    local endNode = self._grid:getNodeAt(endX, endY, endZ)
    if not startNode or not endNode then
      return nil
    end

    startNode._heading = ih
    endNode._heading = oh

    assert(startNode, ('Invalid location [%d, %d, %d]'):format(startX, startY, startZ))
    assert(endNode and self._grid:isWalkableAt(endX, endY, endZ),
      ('Invalid or unreachable location [%d, %d, %d]'):format(endX, endY, endZ))
    local _endNode = Finders[self._finder](self, startNode, endNode, clearance, toClear)
    if _endNode then
			return Utils.traceBackPath(self, _endNode, startNode)
    end
    return nil
  end

  --- Resets the `pathfinder`. This function is called internally between successive pathfinding calls, so you should not
	-- use it explicitely, unless under specific circumstances.
  -- @class function
	-- @treturn pathfinder self (the calling `pathfinder` itself, can be chained)
	-- @usage local path, len = myFinder:getPath(1,1,5,5)
	function Pathfinder:reset()
    for node in pairs(toClear) do node:reset() end
    toClear = {}
		return self
	end


  -- Returns Pathfinder class
	Pathfinder._VERSION = _VERSION
	Pathfinder._RELEASEDATE = _RELEASEDATE
  return setmetatable(Pathfinder,{
    __call = function(self,...)
      return self:new(...)
    end
  })

end