/* $Id$ */

/*
 * This file is part of OpenTTD.
 * OpenTTD 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, version 2.
 * OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */

/** @file yapf_node_rail.hpp Node tailored for rail pathfinding. */

#ifndef YAPF_NODE_RAIL_HPP
#define YAPF_NODE_RAIL_HPP

/** key for cached segment cost for rail YAPF */
struct CYapfRailSegmentKey
{
	uint32    m_value;

	inline CYapfRailSegmentKey(const CYapfRailSegmentKey& src) : m_value(src.m_value) {}

	inline CYapfRailSegmentKey(const CYapfNodeKeyTrackDir& node_key)
	{
		Set(node_key);
	}

	inline void Set(const CYapfRailSegmentKey& src)
	{
		m_value = src.m_value;
	}

	inline void Set(const CYapfNodeKeyTrackDir& node_key)
	{
		m_value = (((int)node_key.m_tile) << 4) | node_key.m_td;
	}

	inline int32 CalcHash() const
	{
		return m_value;
	}

	inline TileIndex GetTile() const
	{
		return (TileIndex)(m_value >> 4);
	}

	inline Trackdir GetTrackdir() const
	{
		return (Trackdir)(m_value & 0x0F);
	}

	inline bool operator == (const CYapfRailSegmentKey& other) const
	{
		return m_value == other.m_value;
	}

	void Dump(DumpTarget &dmp) const
	{
		dmp.WriteTile("tile", GetTile());
		dmp.WriteEnumT("td", GetTrackdir());
	}
};

/* Enum used in PfCalcCost() to see why was the segment closed. */
enum EndSegmentReason {
	/* The following reasons can be saved into cached segment */
	ESR_DEAD_END = 0,      ///< track ends here
	ESR_RAIL_TYPE,         ///< the next tile has a different rail type than our tiles
	ESR_INFINITE_LOOP,     ///< infinite loop detected
	ESR_SEGMENT_TOO_LONG,  ///< the segment is too long (possible infinite loop)
	ESR_CHOICE_FOLLOWS,    ///< the next tile contains a choice (the track splits to more than one segments)
	ESR_DEPOT,             ///< stop in the depot (could be a target next time)
	ESR_WAYPOINT,          ///< waypoint encountered (could be a target next time)
	ESR_STATION,           ///< station encountered (could be a target next time)
	ESR_SAFE_TILE,         ///< safe waiting position found (could be a target)

	/* The following reasons are used only internally by PfCalcCost().
	 *  They should not be found in the cached segment. */
	ESR_PATH_TOO_LONG,     ///< the path is too long (searching for the nearest depot in the given radius)
	ESR_FIRST_TWO_WAY_RED, ///< first signal was 2-way and it was red
	ESR_LOOK_AHEAD_END,    ///< we have just passed the last look-ahead signal
	ESR_TARGET_REACHED,    ///< we have just reached the destination

	/* Special values */
	ESR_NONE = 0xFF,          ///< no reason to end the segment here
};

enum EndSegmentReasonBits {
	ESRB_NONE = 0,

	ESRB_DEAD_END          = 1 << ESR_DEAD_END,
	ESRB_RAIL_TYPE         = 1 << ESR_RAIL_TYPE,
	ESRB_INFINITE_LOOP     = 1 << ESR_INFINITE_LOOP,
	ESRB_SEGMENT_TOO_LONG  = 1 << ESR_SEGMENT_TOO_LONG,
	ESRB_CHOICE_FOLLOWS    = 1 << ESR_CHOICE_FOLLOWS,
	ESRB_DEPOT             = 1 << ESR_DEPOT,
	ESRB_WAYPOINT          = 1 << ESR_WAYPOINT,
	ESRB_STATION           = 1 << ESR_STATION,
	ESRB_SAFE_TILE         = 1 << ESR_SAFE_TILE,

	ESRB_PATH_TOO_LONG     = 1 << ESR_PATH_TOO_LONG,
	ESRB_FIRST_TWO_WAY_RED = 1 << ESR_FIRST_TWO_WAY_RED,
	ESRB_LOOK_AHEAD_END    = 1 << ESR_LOOK_AHEAD_END,
	ESRB_TARGET_REACHED    = 1 << ESR_TARGET_REACHED,

	/* Additional (composite) values. */

	/* What reasons mean that the target can be found and needs to be detected. */
	ESRB_POSSIBLE_TARGET = ESRB_DEPOT | ESRB_WAYPOINT | ESRB_STATION | ESRB_SAFE_TILE,

	/* What reasons can be stored back into cached segment. */
	ESRB_CACHED_MASK = ESRB_DEAD_END | ESRB_RAIL_TYPE | ESRB_INFINITE_LOOP | ESRB_SEGMENT_TOO_LONG | ESRB_CHOICE_FOLLOWS | ESRB_DEPOT | ESRB_WAYPOINT | ESRB_STATION | ESRB_SAFE_TILE,

	/* Reasons to abort pathfinding in this direction. */
	ESRB_ABORT_PF_MASK = ESRB_DEAD_END | ESRB_PATH_TOO_LONG | ESRB_INFINITE_LOOP | ESRB_FIRST_TWO_WAY_RED,
};

DECLARE_ENUM_AS_BIT_SET(EndSegmentReasonBits)

inline CStrA ValueStr(EndSegmentReasonBits bits)
{
	static const char * const end_segment_reason_names[] = {
		"DEAD_END", "RAIL_TYPE", "INFINITE_LOOP", "SEGMENT_TOO_LONG", "CHOICE_FOLLOWS",
		"DEPOT", "WAYPOINT", "STATION", "SAFE_TILE",
		"PATH_TOO_LONG", "FIRST_TWO_WAY_RED", "LOOK_AHEAD_END", "TARGET_REACHED"
	};

	CStrA out;
	out.Format("0x%04X (%s)", bits, ComposeNameT(bits, end_segment_reason_names, "UNK", ESRB_NONE, "NONE").Data());
	return out.Transfer();
}

/** cached segment cost for rail YAPF */
struct CYapfRailSegment
{
	typedef CYapfRailSegmentKey Key;

	CYapfRailSegmentKey    m_key;
	TileIndex              m_last_tile;
	Trackdir               m_last_td;
	int                    m_cost;
	TileIndex              m_last_signal_tile;
	Trackdir               m_last_signal_td;
	EndSegmentReasonBits   m_end_segment_reason;
	CYapfRailSegment      *m_hash_next;

	inline CYapfRailSegment(const CYapfRailSegmentKey& key)
		: m_key(key)
		, m_last_tile(INVALID_TILE)
		, m_last_td(INVALID_TRACKDIR)
		, m_cost(-1)
		, m_last_signal_tile(INVALID_TILE)
		, m_last_signal_td(INVALID_TRACKDIR)
		, m_end_segment_reason(ESRB_NONE)
		, m_hash_next(NULL)
	{}

	inline const Key& GetKey() const
	{
		return m_key;
	}

	inline TileIndex GetTile() const
	{
		return m_key.GetTile();
	}

	inline CYapfRailSegment *GetHashNext()
	{
		return m_hash_next;
	}

	inline void SetHashNext(CYapfRailSegment *next)
	{
		m_hash_next = next;
	}

	void Dump(DumpTarget &dmp) const
	{
		dmp.WriteStructT("m_key", &m_key);
		dmp.WriteTile("m_last_tile", m_last_tile);
		dmp.WriteEnumT("m_last_td", m_last_td);
		dmp.WriteLine("m_cost = %d", m_cost);
		dmp.WriteTile("m_last_signal_tile", m_last_signal_tile);
		dmp.WriteEnumT("m_last_signal_td", m_last_signal_td);
		dmp.WriteEnumT("m_end_segment_reason", m_end_segment_reason);
	}
};

/** Yapf Node for rail YAPF */
template <class Tkey_>
struct CYapfRailNodeT
	: CYapfNodeT<Tkey_, CYapfRailNodeT<Tkey_> >
{
	typedef CYapfNodeT<Tkey_, CYapfRailNodeT<Tkey_> > base;
	typedef CYapfRailSegment CachedData;

	CYapfRailSegment *m_segment;
	uint16            m_num_signals_passed;
	union {
		uint32          m_inherited_flags;
		struct {
			bool          m_targed_seen : 1;
			bool          m_choice_seen : 1;
			bool          m_last_signal_was_red : 1;
		} flags_s;
	} flags_u;
	SignalType        m_last_red_signal_type;
	SignalType        m_last_signal_type;

	inline void Set(CYapfRailNodeT *parent, TileIndex tile, Trackdir td, bool is_choice)
	{
		base::Set(parent, tile, td, is_choice);
		m_segment = NULL;
		if (parent == NULL) {
			m_num_signals_passed      = 0;
			flags_u.m_inherited_flags = 0;
			m_last_red_signal_type    = SIGTYPE_NORMAL;
			/* We use PBS as initial signal type because if we are in
			 * a PBS section and need to route, i.e. we're at a safe
			 * waiting point of a station, we need to account for the
			 * reservation costs. If we are in a normal block then we
			 * should be alone in there and as such the reservation
			 * costs should be 0 anyway. If there would be another
			 * train in the block, i.e. passing signals at danger
			 * then avoiding that train with help of the reservation
			 * costs is not a bad thing, actually it would probably
			 * be a good thing to do. */
			m_last_signal_type        = SIGTYPE_PBS;
		} else {
			m_num_signals_passed      = parent->m_num_signals_passed;
			flags_u.m_inherited_flags = parent->flags_u.m_inherited_flags;
			m_last_red_signal_type    = parent->m_last_red_signal_type;
			m_last_signal_type        = parent->m_last_signal_type;
		}
		flags_u.flags_s.m_choice_seen |= is_choice;
	}

	inline TileIndex GetLastTile() const
	{
		assert(m_segment != NULL);
		return m_segment->m_last_tile;
	}

	inline Trackdir GetLastTrackdir() const
	{
		assert(m_segment != NULL);
		return m_segment->m_last_td;
	}

	inline void SetLastTileTrackdir(TileIndex tile, Trackdir td)
	{
		assert(m_segment != NULL);
		m_segment->m_last_tile = tile;
		m_segment->m_last_td = td;
	}

	template <class Tbase, class Tfunc, class Tpf>
	bool IterateTiles(const Train *v, Tpf &yapf, Tbase &obj, bool (Tfunc::*func)(TileIndex, Trackdir)) const
	{
		typename Tbase::TrackFollower ft(v, yapf.GetCompatibleRailTypes());
		TileIndex cur = base::GetTile();
		Trackdir  cur_td = base::GetTrackdir();

		while (cur != GetLastTile() || cur_td != GetLastTrackdir()) {
			if (!((obj.*func)(cur, cur_td))) return false;

			ft.Follow(cur, cur_td);
			cur = ft.m_new_tile;
			assert(KillFirstBit(ft.m_new_td_bits) == TRACKDIR_BIT_NONE);
			cur_td = FindFirstTrackdir(ft.m_new_td_bits);
		}

		return (obj.*func)(cur, cur_td);
	}

	void Dump(DumpTarget &dmp) const
	{
		base::Dump(dmp);
		dmp.WriteStructT("m_segment", m_segment);
		dmp.WriteLine("m_num_signals_passed = %d", m_num_signals_passed);
		dmp.WriteLine("m_targed_seen = %s", flags_u.flags_s.m_targed_seen ? "Yes" : "No");
		dmp.WriteLine("m_choice_seen = %s", flags_u.flags_s.m_choice_seen ? "Yes" : "No");
		dmp.WriteLine("m_last_signal_was_red = %s", flags_u.flags_s.m_last_signal_was_red ? "Yes" : "No");
		dmp.WriteEnumT("m_last_red_signal_type", m_last_red_signal_type);
	}
};

/* now define two major node types (that differ by key type) */
typedef CYapfRailNodeT<CYapfNodeKeyExitDir>  CYapfRailNodeExitDir;
typedef CYapfRailNodeT<CYapfNodeKeyTrackDir> CYapfRailNodeTrackDir;

/* Default NodeList types */
typedef CNodeList_HashTableT<CYapfRailNodeExitDir , 8, 10> CRailNodeListExitDir;
typedef CNodeList_HashTableT<CYapfRailNodeTrackDir, 8, 10> CRailNodeListTrackDir;

#endif /* YAPF_NODE_RAIL_HPP */