/* $Id$ */

/**

 * A Road Pathfinder.

 *  This road pathfinder tries to find a buildable / existing route for

 *  road vehicles. You can changes the costs below using for example

 *  roadpf.cost.turn = 30. Note that it's not allowed to change the cost

 *  between consecutive calls to FindPath. You can change the cost before

 *  the first call to FindPath and after FindPath has returned an actual

 *  route. To use only existing roads, set cost.no_existing_road to

 *  cost.max_cost.

 */

class Road

{

	_aystar_class = import("graph.aystar", "", 4);

	_max_cost = null;              ///< The maximum cost for a route.

	_cost_tile = null;             ///< The cost for a single tile.

	_cost_no_existing_road = null; ///< The cost that is added to _cost_tile if no road exists yet.

	_cost_turn = null;             ///< The cost that is added to _cost_tile if the direction changes.

	_cost_slope = null;            ///< The extra cost if a road tile is sloped.

	_cost_bridge_per_tile = null;  ///< The cost per tile of a new bridge, this is added to _cost_tile.

	_cost_tunnel_per_tile = null;  ///< The cost per tile of a new tunnel, this is added to _cost_tile.

	_cost_coast = null;            ///< The extra cost for a coast tile.

	_pathfinder = null;            ///< A reference to the used AyStar object.

	_max_bridge_length = null;     ///< The maximum length of a bridge that will be build.

	_max_tunnel_length = null;     ///< The maximum length of a tunnel that will be build.

	cost = null;                   ///< Used to change the costs.

	_running = null;

	constructor()

	{

		this._max_cost = 10000000;

		this._cost_tile = 100;

		this._cost_no_existing_road = 40;

		this._cost_turn = 100;

		this._cost_slope = 200;

		this._cost_bridge_per_tile = 150;

		this._cost_tunnel_per_tile = 120;

		this._cost_coast = 20;

		this._max_bridge_length = 10;

		this._max_tunnel_length = 20;

		this._pathfinder = this._aystar_class(this._Cost, this._Estimate, this._Neighbours, this._CheckDirection, this, this, this, this);

		this.cost = this.Cost(this);

		this._running = false;

	}

	/**

	 * Initialize a path search between sources and goals.

	 * @param sources The source tiles.

	 * @param goals The target tiles.

	 * @see AyStar::InitializePath()

	 */

	function InitializePath(sources, goals) {

		local nsources = [];

		foreach (node in sources) {

			nsources.push([node, 0xFF]);

		}

		this._pathfinder.InitializePath(nsources, goals);

	}

	/**

	 * Try to find the path as indicated with InitializePath with the lowest cost.

	 * @param iterations After how many iterations it should abort for a moment.

	 *  This value should either be -1 for infinite, or > 0. Any other value

	 *  aborts immediatly and will never find a path.

	 * @return A route if one was found, or false if the amount of iterations was

	 *  reached, or null if no path was found.

	 *  You can call this function over and over as long as it returns false,

	 *  which is an indication it is not yet done looking for a route.

	 * @see AyStar::FindPath()

	 */

	function FindPath(iterations);

};

class Road.Cost

{

	_main = null;

	function _set(idx, val)

	{

		if (this._main._running) throw("You are not allowed to change parameters of a running pathfinder.");

		switch (idx) {

			case "max_cost":          this._main._max_cost = val; break;

			case "tile":              this._main._cost_tile = val; break;

			case "no_existing_road":  this._main._cost_no_existing_road = val; break;

			case "turn":              this._main._cost_turn = val; break;

			case "slope":             this._main._cost_slope = val; break;

			case "bridge_per_tile":   this._main._cost_bridge_per_tile = val; break;

			case "tunnel_per_tile":   this._main._cost_tunnel_per_tile = val; break;

			case "coast":             this._main._cost_coast = val; break;

			case "max_bridge_length": this._main._max_bridge_length = val; break;

			case "max_tunnel_length": this._main._max_tunnel_length = val; break;

			default: throw("the index '" + idx + "' does not exist");

		}

		return val;

	}

	function _get(idx)

	{

		switch (idx) {

			case "max_cost":          return this._main._max_cost;

			case "tile":              return this._main._cost_tile;

			case "no_existing_road":  return this._main._cost_no_existing_road;

			case "turn":              return this._main._cost_turn;

			case "slope":             return this._main._cost_slope;

			case "bridge_per_tile":   return this._main._cost_bridge_per_tile;

			case "tunnel_per_tile":   return this._main._cost_tunnel_per_tile;

			case "coast":             return this._main._cost_coast;

			case "max_bridge_length": return this._main._max_bridge_length;

			case "max_tunnel_length": return this._main._max_tunnel_length;

			default: throw("the index '" + idx + "' does not exist");

		}

	}

	constructor(main)

	{

		this._main = main;

	}

};

function Road::FindPath(iterations)

{

	local test_mode = AITestMode();

	local ret = this._pathfinder.FindPath(iterations);

	this._running = (ret == false) ? true : false;

	return ret;

}

function Road::_GetBridgeNumSlopes(end_a, end_b)

{

	local slopes = 0;

	local direction = (end_b - end_a) / AIMap.DistanceManhattan(end_a, end_b);

	local slope = AITile.GetSlope(end_a);

	if (!((slope == AITile.SLOPE_NE && direction == 1) || (slope == AITile.SLOPE_SE && direction == -AIMap.GetMapSizeX()) ||

		(slope == AITile.SLOPE_SW && direction == -1) || (slope == AITile.SLOPE_NW && direction == AIMap.GetMapSizeX()) ||

		 slope == AITile.SLOPE_N || slope == AITile.SLOPE_E || slope == AITile.SLOPE_S || slope == AITile.SLOPE_W)) {

		slopes++;

	}

	local slope = AITile.GetSlope(end_b);

	direction = -direction;

	if (!((slope == AITile.SLOPE_NE && direction == 1) || (slope == AITile.SLOPE_SE && direction == -AIMap.GetMapSizeX()) ||

		(slope == AITile.SLOPE_SW && direction == -1) || (slope == AITile.SLOPE_NW && direction == AIMap.GetMapSizeX()) ||

		 slope == AITile.SLOPE_N || slope == AITile.SLOPE_E || slope == AITile.SLOPE_S || slope == AITile.SLOPE_W)) {

		slopes++;

	}

	return slopes;

}

function Road::_Cost(path, new_tile, new_direction, self)

{

	/* path == null means this is the first node of a path, so the cost is 0. */

	if (path == null) return 0;

	local prev_tile = path.GetTile();

	/* If the new tile is a bridge / tunnel tile, check whether we came from the other

	 * end of the bridge / tunnel or if we just entered the bridge / tunnel. */

	if (AIBridge.IsBridgeTile(new_tile)) {

		if (AIBridge.GetOtherBridgeEnd(new_tile) != prev_tile) return path.GetCost() + self._cost_tile;

		return path.GetCost() + AIMap.DistanceManhattan(new_tile, prev_tile) * self._cost_tile + self._GetBridgeNumSlopes(new_tile, prev_tile) * self._cost_slope;

	}

	if (AITunnel.IsTunnelTile(new_tile)) {

		if (AITunnel.GetOtherTunnelEnd(new_tile) != prev_tile) return path.GetCost() + self._cost_tile;

		return path.GetCost() + AIMap.DistanceManhattan(new_tile, prev_tile) * self._cost_tile;

	}

	/* If the two tiles are more then 1 tile apart, the pathfinder wants a bridge or tunnel

	 * to be build. It isn't an existing bridge / tunnel, as that case is already handled. */

	if (AIMap.DistanceManhattan(new_tile, prev_tile) > 1) {

		/* Check if we should build a bridge or a tunnel. */

		if (AITunnel.GetOtherTunnelEnd(new_tile) == prev_tile) {

			return path.GetCost() + AIMap.DistanceManhattan(new_tile, prev_tile) * (self._cost_tile + self._cost_tunnel_per_tile);

		} else {

			return path.GetCost() + AIMap.DistanceManhattan(new_tile, prev_tile) * (self._cost_tile + self._cost_bridge_per_tile) + self._GetBridgeNumSlopes(new_tile, prev_tile) * self._cost_slope;

		}

	}

	/* Check for a turn. We do this by substracting the TileID of the current node from

	 * the TileID of the previous node and comparing that to the difference between the

	 * previous node and the node before that. */

	local cost = self._cost_tile;

	if (path.GetParent() != null && (prev_tile - path.GetParent().GetTile()) != (new_tile - prev_tile) &&

		AIMap.DistanceManhattan(path.GetParent().GetTile(), prev_tile) == 1) {

		cost += self._cost_turn;

	}

	/* Check if the new tile is a coast tile. */

	if (AITile.IsCoastTile(new_tile)) {

		cost += self._cost_coast;

	}

	/* Check if the last tile was sloped. */

	if (path.GetParent() != null && !AIBridge.IsBridgeTile(prev_tile) && !AITunnel.IsTunnelTile(prev_tile) &&

	    self._IsSlopedRoad(path.GetParent().GetTile(), prev_tile, new_tile)) {

		cost += self._cost_slope;

	}

	if (!AIRoad.AreRoadTilesConnected(prev_tile, new_tile)) {

		cost += self._cost_no_existing_road;

	}

	return path.GetCost() + cost;

}

function Road::_Estimate(cur_tile, cur_direction, goal_tiles, self)

{

	local min_cost = self._max_cost;

	/* As estimate we multiply the lowest possible cost for a single tile with

	 * with the minimum number of tiles we need to traverse. */

	foreach (tile in goal_tiles) {

		min_cost = min(AIMap.DistanceManhattan(cur_tile, tile) * self._cost_tile, min_cost);

	}

	return min_cost;

}

function Road::_Neighbours(path, cur_node, self)

{

	/* self._max_cost is the maximum path cost, if we go over it, the path isn't valid. */

	if (path.GetCost() >= self._max_cost) return [];

	local tiles = [];

	/* Check if the current tile is part of a bridge or tunnel. */

	if ((AIBridge.IsBridgeTile(cur_node) || AITunnel.IsTunnelTile(cur_node)) &&

	     AITile.HasTransportType(cur_node, AITile.TRANSPORT_ROAD)) {

		local other_end = AIBridge.IsBridgeTile(cur_node) ? AIBridge.GetOtherBridgeEnd(cur_node) : AITunnel.GetOtherTunnelEnd(cur_node);

		local next_tile = cur_node + (cur_node - other_end) / AIMap.DistanceManhattan(cur_node, other_end);

		if (AIRoad.AreRoadTilesConnected(cur_node, next_tile) || AITile.IsBuildable(next_tile) || AIRoad.IsRoadTile(next_tile)) {

			tiles.push([next_tile, self._GetDirection(cur_node, next_tile, false)]);

		}

		/* The other end of the bridge / tunnel is a neighbour. */

		tiles.push([other_end, self._GetDirection(next_tile, cur_node, true) << 4]);

	} else if (path.GetParent() != null && AIMap.DistanceManhattan(cur_node, path.GetParent().GetTile()) > 1) {

		local other_end = path.GetParent().GetTile();

		local next_tile = cur_node + (cur_node - other_end) / AIMap.DistanceManhattan(cur_node, other_end);

		if (AIRoad.AreRoadTilesConnected(cur_node, next_tile) || AIRoad.BuildRoad(cur_node, next_tile)) {

			tiles.push([next_tile, self._GetDirection(cur_node, next_tile, false)]);

		}

	} else {

		local offsets = [AIMap.GetTileIndex(0, 1), AIMap.GetTileIndex(0, -1),

		                 AIMap.GetTileIndex(1, 0), AIMap.GetTileIndex(-1, 0)];

		/* Check all tiles adjacent to the current tile. */

		foreach (offset in offsets) {

			local next_tile = cur_node + offset;

			/* We add them to the to the neighbours-list if one of the following applies:

			 * 1) There already is a connections between the current tile and the next tile.

			 * 2) We can build a road to the next tile.

			 * 3) The next tile is the entrance of a tunnel / bridge in the correct direction. */

			if (AIRoad.AreRoadTilesConnected(cur_node, next_tile)) {

				tiles.push([next_tile, self._GetDirection(cur_node, next_tile, false)]);

			} else if ((AITile.IsBuildable(next_tile) || AIRoad.IsRoadTile(next_tile)) &&

					(path.GetParent() == null || AIRoad.CanBuildConnectedRoadPartsHere(cur_node, path.GetParent().GetTile(), next_tile)) &&

					AIRoad.BuildRoad(cur_node, next_tile)) {

				tiles.push([next_tile, self._GetDirection(cur_node, next_tile, false)]);

			} else if (self._CheckTunnelBridge(cur_node, next_tile)) {

				tiles.push([next_tile, self._GetDirection(cur_node, next_tile, false)]);

			}

		}

		if (path.GetParent() != null) {

			local bridges = self._GetTunnelsBridges(path.GetParent().GetTile(), cur_node, self._GetDirection(path.GetParent().GetTile(), cur_node, true) << 4);

			foreach (tile in bridges) {

				tiles.push(tile);

			}

		}

	}

	return tiles;

}

function Road::_CheckDirection(tile, existing_direction, new_direction, self)

{

	return false;

}

function Road::_GetDirection(from, to, is_bridge)

{

	if (!is_bridge && AITile.GetSlope(to) == AITile.SLOPE_FLAT) return 0xFF;

	if (from - to == 1) return 1;

	if (from - to == -1) return 2;

	if (from - to == AIMap.GetMapSizeX()) return 4;

	if (from - to == -AIMap.GetMapSizeX()) return 8;

}

/**

 * Get a list of all bridges and tunnels that can be build from the

 * current tile. Bridges will only be build starting on non-flat tiles

 * for performance reasons. Tunnels will only be build if no terraforming

 * is needed on both ends.

 */

function Road::_GetTunnelsBridges(last_node, cur_node, bridge_dir)

{

	local slope = AITile.GetSlope(cur_node);

	if (slope == AITile.SLOPE_FLAT) return [];

	local tiles = [];

	for (local i = 2; i < this._max_bridge_length; i++) {

		local bridge_list = AIBridgeList_Length(i + 1);

		local target = cur_node + i * (cur_node - last_node);

		if (!bridge_list.IsEmpty() && AIBridge.BuildBridge(AIVehicle.VEHICLE_ROAD, bridge_list.Begin(), cur_node, target)) {

			tiles.push([target, bridge_dir]);

		}

	}

	if (slope != AITile.SLOPE_SW && slope != AITile.SLOPE_NW && slope != AITile.SLOPE_SE && slope != AITile.SLOPE_NE) return tiles;

	local other_tunnel_end = AITunnel.GetOtherTunnelEnd(cur_node);

	if (!AIMap.IsValidTile(other_tunnel_end)) return tiles;

	local tunnel_length = AIMap.DistanceManhattan(cur_node, other_tunnel_end);

	local prev_tile = cur_node + (cur_node - other_tunnel_end) / tunnel_length;

	if (AITunnel.GetOtherTunnelEnd(other_tunnel_end) == cur_node && tunnel_length >= 2 &&

			prev_tile == last_node && tunnel_length < _max_tunnel_length && AITunnel.BuildTunnel(AIVehicle.VEHICLE_ROAD, cur_node)) {

		tiles.push([other_tunnel_end, bridge_dir]);

	}

	return tiles;

}

function Road::_IsSlopedRoad(start, middle, end)

{

	local NW = 0; //Set to true if we want to build a road to / from the north-west

	local NE = 0; //Set to true if we want to build a road to / from the north-east

	local SW = 0; //Set to true if we want to build a road to / from the south-west

	local SE = 0; //Set to true if we want to build a road to / from the south-east

	if (middle - AIMap.GetMapSizeX() == start || middle - AIMap.GetMapSizeX() == end) NW = 1;

	if (middle - 1 == start || middle - 1 == end) NE = 1;

	if (middle + AIMap.GetMapSizeX() == start || middle + AIMap.GetMapSizeX() == end) SE = 1;

	if (middle + 1 == start || middle + 1 == end) SW = 1;

	/* If there is a turn in the current tile, it can't be sloped. */

	if ((NW || SE) && (NE || SW)) return false;

	local slope = AITile.GetSlope(middle);

	/* A road on a steep slope is always sloped. */

	if (AITile.IsSteepSlope(slope)) return true;

	/* If only one corner is raised, the road is sloped. */

	if (slope == AITile.SLOPE_N || slope == AITile.SLOPE_W) return true;

	if (slope == AITile.SLOPE_S || slope == AITile.SLOPE_E) return true;

	if (NW && (slope == AITile.SLOPE_NW || slope == AITile.SLOPE_SE)) return true;

	if (NE && (slope == AITile.SLOPE_NE || slope == AITile.SLOPE_SW)) return true;

	return false;

}

function Road::_CheckTunnelBridge(current_tile, new_tile)

{

	if (!AIBridge.IsBridgeTile(new_tile) && !AITunnel.IsTunnelTile(new_tile)) return false;

	local dir = new_tile - current_tile;

	local other_end = AIBridge.IsBridgeTile(new_tile) ? AIBridge.GetOtherBridgeEnd(new_tile) : AITunnel.GetOtherTunnelEnd(new_tile);

	local dir2 = other_end - new_tile;

	if ((dir < 0 && dir2 > 0) || (dir > 0 && dir2 < 0)) return false;

	dir = abs(dir);

	dir2 = abs(dir2);

	if ((dir >= AIMap.GetMapSizeX() && dir2 < AIMap.GetMapSizeX()) ||

	    (dir < AIMap.GetMapSizeX() && dir2 >= AIMap.GetMapSizeX())) return false;

	return true;

}