/* $Id$ */

/*
 * 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 cargopacket.cpp Implementation of the cargo packets. */

#include "stdafx.h"
#include "core/pool_func.hpp"
#include "economy_base.h"

/* Initialize the cargopacket-pool */
CargoPacketPool _cargopacket_pool("CargoPacket");
INSTANTIATE_POOL_METHODS(CargoPacket)

/**
 * Create a new packet for savegame loading.
 */
CargoPacket::CargoPacket()
{
	this->source_type = ST_INDUSTRY;
	this->source_id   = INVALID_SOURCE;
}

/**
 * Creates a new cargo packet.
 * @param source      Source station of the packet.
 * @param source_xy   Source location of the packet.
 * @param count       Number of cargo entities to put in this packet.
 * @param source_type 'Type' of source the packet comes from (for subsidies).
 * @param source_id   Actual source of the packet (for subsidies).
 * @pre count != 0
 * @note We have to zero memory ourselves here because we are using a 'new'
 * that, in contrary to all other pools, does not memset to 0.
 */
CargoPacket::CargoPacket(StationID source, TileIndex source_xy, uint16 count, SourceType source_type, SourceID source_id) :
	feeder_share(0),
	count(count),
	days_in_transit(0),
	source_id(source_id),
	source(source),
	source_xy(source_xy),
	loaded_at_xy(0)
{
	assert(count != 0);
	this->source_type  = source_type;
}

/**
 * Creates a new cargo packet. Initializes the fields that cannot be changed later.
 * Used when loading or splitting packets.
 * @param count           Number of cargo entities to put in this packet.
 * @param days_in_transit Number of days the cargo has been in transit.
 * @param source          Station the cargo was initially loaded.
 * @param source_xy       Station location the cargo was initially loaded.
 * @param loaded_at_xy    Location the cargo was loaded last.
 * @param feeder_share    Feeder share the packet has already accumulated.
 * @param source_type     'Type' of source the packet comes from (for subsidies).
 * @param source_id       Actual source of the packet (for subsidies).
 * @note We have to zero memory ourselves here because we are using a 'new'
 * that, in contrary to all other pools, does not memset to 0.
 */
CargoPacket::CargoPacket(uint16 count, byte days_in_transit, StationID source, TileIndex source_xy, TileIndex loaded_at_xy, Money feeder_share, SourceType source_type, SourceID source_id) :
		feeder_share(feeder_share),
		count(count),
		days_in_transit(days_in_transit),
		source_id(source_id),
		source(source),
		source_xy(source_xy),
		loaded_at_xy(loaded_at_xy)
{
	assert(count != 0);
	this->source_type = source_type;
}

/**
 * Split this packet in two and return the split off part.
 * @param new_size Size of the split part.
 * @return Split off part, or NULL if no packet could be allocated!
 */
inline CargoPacket *CargoPacket::Split(uint new_size)
{
	if (!CargoPacket::CanAllocateItem()) return NULL;

	Money fs = this->FeederShare(new_size);
	CargoPacket *cp_new = new CargoPacket(new_size, this->days_in_transit, this->source, this->source_xy, this->loaded_at_xy, fs, this->source_type, this->source_id);
	this->feeder_share -= fs;
	this->count -= new_size;
	return cp_new;
}

/**
 * Merge another packet into this one.
 * @param cp Packet to be merged in.
 */
inline void CargoPacket::Merge(CargoPacket *cp)
{
	this->count += cp->count;
	this->feeder_share += cp->feeder_share;
	delete cp;
}

/**
 * Reduce the packet by the given amount and remove the feeder share.
 * @param count Amount to be removed.
 */
inline void CargoPacket::Reduce(uint count)
{
	assert(count < this->count);
	this->feeder_share -= this->FeederShare(count);
	this->count -= count;
}

/**
 * Invalidates (sets source_id to INVALID_SOURCE) all cargo packets from given source.
 * @param src_type Type of source.
 * @param src Index of source.
 */
/* static */ void CargoPacket::InvalidateAllFrom(SourceType src_type, SourceID src)
{
	CargoPacket *cp;
	FOR_ALL_CARGOPACKETS(cp) {
		if (cp->source_type == src_type && cp->source_id == src) cp->source_id = INVALID_SOURCE;
	}
}

/**
 * Invalidates (sets source to INVALID_STATION) all cargo packets from given station.
 * @param sid Station that gets removed.
 */
/* static */ void CargoPacket::InvalidateAllFrom(StationID sid)
{
	CargoPacket *cp;
	FOR_ALL_CARGOPACKETS(cp) {
		if (cp->source == sid) cp->source = INVALID_STATION;
	}
}

/*
 *
 * Cargo list implementation
 *
 */

/**
 * Destroy the cargolist ("frees" all cargo packets).
 */
template <class Tinst>
CargoList<Tinst>::~CargoList()
{
	for (Iterator it(this->packets.begin()); it != this->packets.end(); ++it) {
		delete *it;
	}
}

/**
 * Empty the cargo list, but don't free the cargo packets;
 * the cargo packets are cleaned by CargoPacket's CleanPool.
 */
template <class Tinst>
void CargoList<Tinst>::OnCleanPool()
{
	this->packets.clear();
}

/**
 * Update the cached values to reflect the removal of this packet or part of it.
 * Decreases count and days_in_transit.
 * @param cp Packet to be removed from cache.
 * @param count Amount of cargo from the given packet to be removed.
 */
template <class Tinst>
void CargoList<Tinst>::RemoveFromCache(const CargoPacket *cp, uint count)
{
	assert(count <= cp->count);
	this->count                 -= count;
	this->cargo_days_in_transit -= cp->days_in_transit * count;
}

/**
 * Update the cache to reflect adding of this packet.
 * Increases count and days_in_transit.
 * @param cp New packet to be inserted.
 */
template <class Tinst>
void CargoList<Tinst>::AddToCache(const CargoPacket *cp)
{
	this->count                 += cp->count;
	this->cargo_days_in_transit += cp->days_in_transit * cp->count;
}

/**
 * Appends the given cargo packet. Tries to merge it with another one in the
 * packets list. If no fitting packet is found, appends it.
 * @warning After appending this packet may not exist anymore!
 * @note Do not use the cargo packet anymore after it has been appended to this CargoList!
 * @param cp Cargo packet to add.
 * @pre cp != NULL
 */
template <class Tinst>
void CargoList<Tinst>::Append(CargoPacket *cp)
{
	assert(cp != NULL);
	static_cast<Tinst *>(this)->AddToCache(cp);

	for (List::reverse_iterator it(this->packets.rbegin()); it != this->packets.rend(); it++) {
		if (CargoList<Tinst>::TryMerge(*it, cp)) return;
	}

	/* The packet could not be merged with another one */
	this->packets.push_back(cp);
}

/**
 * Truncates the cargo in this list to the given amount. It leaves the
 * first count cargo entities and removes the rest.
 * @param max_move Maximum amount of entities to be removed from the list.
 * @return Amount of entities actually moved.
 */
template <class Tinst>
uint CargoList<Tinst>::Truncate(uint max_move)
{
	max_move = min(this->count, max_move);
	uint max_remaining = this->count - max_move;
	for (Iterator it(packets.begin()); it != packets.end(); /* done during loop*/) {
		CargoPacket *cp = *it;
		if (max_remaining == 0) {
			/* Nothing should remain, just remove the packets. */
			it = this->packets.erase(it);
			static_cast<Tinst *>(this)->RemoveFromCache(cp, cp->count);
			delete cp;
			continue;
		}

		uint local_count = cp->count;
		if (local_count > max_remaining) {
			uint diff = local_count - max_remaining;
			static_cast<Tinst *>(this)->RemoveFromCache(cp, diff);
			cp->Reduce(diff);
			max_remaining = 0;
		} else {
			max_remaining -= local_count;
		}
		++it;
	}
	return max_move;
}

/**
 * Moves the given amount of cargo to another list.
 * Depending on the value of mta the side effects of this function differ:
 *  - MTA_FINAL_DELIVERY: Destroys the packets that do not originate from a specific station.
 *  - MTA_CARGO_LOAD:     Sets the loaded_at_xy value of the moved packets.
 *  - MTA_TRANSFER:       Just move without side effects.
 *  - MTA_UNLOAD:         Just move without side effects.
 * @param dest  Destination to move the cargo to.
 * @param max_move Amount of cargo entities to move.
 * @param mta   How to handle the moving (side effects).
 * @param data  Depending on mta the data of this variable differs:
 *              - MTA_FINAL_DELIVERY - Station ID of packet's origin not to remove.
 *              - MTA_CARGO_LOAD     - Station's tile index of load.
 *              - MTA_TRANSFER       - Unused.
 *              - MTA_UNLOAD         - Unused.
 * @param payment The payment helper.
 *
 * @pre mta == MTA_FINAL_DELIVERY || dest != NULL
 * @pre mta == MTA_UNLOAD || mta == MTA_CARGO_LOAD || payment != NULL
 * @return True if there are still packets that might be moved from this cargo list.
 */
template <class Tinst>
template <class Tother_inst>
bool CargoList<Tinst>::MoveTo(Tother_inst *dest, uint max_move, MoveToAction mta, CargoPayment *payment, uint data)
{
	assert(mta == MTA_FINAL_DELIVERY || dest != NULL);
	assert(mta == MTA_UNLOAD || mta == MTA_CARGO_LOAD || payment != NULL);

	Iterator it(this->packets.begin());
	while (it != this->packets.end() && max_move > 0) {
		CargoPacket *cp = *it;
		if (cp->source == data && mta == MTA_FINAL_DELIVERY) {
			/* Skip cargo that originated from this station. */
			++it;
			continue;
		}

		if (cp->count <= max_move) {
			/* Can move the complete packet */
			max_move -= cp->count;
			it = this->packets.erase(it);
			static_cast<Tinst *>(this)->RemoveFromCache(cp, cp->count);
			switch (mta) {
				case MTA_FINAL_DELIVERY:
					payment->PayFinalDelivery(cp, cp->count);
					delete cp;
					continue; // of the loop

				case MTA_CARGO_LOAD:
					cp->loaded_at_xy = data;
					break;

				case MTA_TRANSFER:
					cp->feeder_share += payment->PayTransfer(cp, cp->count);
					break;

				case MTA_UNLOAD:
					break;
			}
			dest->Append(cp);
			continue;
		}

		/* Can move only part of the packet */
		if (mta == MTA_FINAL_DELIVERY) {
			/* Final delivery doesn't need package splitting. */
			payment->PayFinalDelivery(cp, max_move);

			/* Remove the delivered data from the cache */
			static_cast<Tinst *>(this)->RemoveFromCache(cp, max_move);
			cp->Reduce(max_move);
		} else {
			/* But... the rest needs package splitting. */
			CargoPacket *cp_new = cp->Split(max_move);

			/* We could not allocate a CargoPacket? Is the map that full? */
			if (cp_new == NULL) return false;

			static_cast<Tinst *>(this)->RemoveFromCache(cp_new, max_move); // this reflects the changes in cp.

			if (mta == MTA_TRANSFER) {
				/* Add the feeder share before inserting in dest. */
				cp_new->feeder_share += payment->PayTransfer(cp_new, max_move);
			} else if (mta == MTA_CARGO_LOAD) {
				cp_new->loaded_at_xy = data;
			}

			dest->Append(cp_new);
		}

		max_move = 0;
	}

	return it != packets.end();
}

/** Invalidates the cached data and rebuilds it. */
template <class Tinst>
void CargoList<Tinst>::InvalidateCache()
{
	this->count = 0;
	this->cargo_days_in_transit = 0;

	for (ConstIterator it(this->packets.begin()); it != this->packets.end(); it++) {
		static_cast<Tinst *>(this)->AddToCache(*it);
	}
}

/**
 * Tries to merge the second packet into the first and return if that was
 * successful.
 * @param icp Packet to be merged into.
 * @param cp Packet to be eliminated.
 * @return If the packets could be merged.
 */
template <class Tinst>
/* static */ bool CargoList<Tinst>::TryMerge(CargoPacket *icp, CargoPacket *cp)
{
	if (Tinst::AreMergable(icp, cp) &&
				icp->count + cp->count <= CargoPacket::MAX_COUNT) {
		icp->Merge(cp);
		return true;
	} else {
		return false;
	}
}

/*
 *
 * Vehicle cargo list implementation.
 *
 */

/**
 * Update the cached values to reflect the removal of this packet or part of it.
 * Decreases count, feeder share and days_in_transit.
 * @param cp Packet to be removed from cache.
 * @param count Amount of cargo from the given packet to be removed.
 */
void VehicleCargoList::RemoveFromCache(const CargoPacket *cp, uint count)
{
	this->feeder_share -= cp->FeederShare(count);
	this->Parent::RemoveFromCache(cp, count);
}

/**
 * Update the cache to reflect adding of this packet.
 * Increases count, feeder share and days_in_transit.
 * @param cp New packet to be inserted.
 */
void VehicleCargoList::AddToCache(const CargoPacket *cp)
{
	this->feeder_share += cp->feeder_share;
	this->Parent::AddToCache(cp);
}

/**
 * Ages the all cargo in this list.
 */
void VehicleCargoList::AgeCargo()
{
	for (ConstIterator it(this->packets.begin()); it != this->packets.end(); it++) {
		CargoPacket *cp = *it;
		/* If we're at the maximum, then we can't increase no more. */
		if (cp->days_in_transit == 0xFF) continue;

		cp->days_in_transit++;
		this->cargo_days_in_transit += cp->count;
	}
}

/** Invalidates the cached data and rebuild it. */
void VehicleCargoList::InvalidateCache()
{
	this->feeder_share = 0;
	this->Parent::InvalidateCache();
}

/*
 * We have to instantiate everything we want to be usable.
 */
template class CargoList<VehicleCargoList>;
template class CargoList<StationCargoList>;

/** Autoreplace Vehicle -> Vehicle 'transfer'. */
template bool CargoList<VehicleCargoList>::MoveTo(VehicleCargoList *, uint max_move, MoveToAction mta, CargoPayment *payment, uint data);
/** Cargo unloading at a station. */
template bool CargoList<VehicleCargoList>::MoveTo(StationCargoList *, uint max_move, MoveToAction mta, CargoPayment *payment, uint data);
/** Cargo loading at a station. */
template bool CargoList<StationCargoList>::MoveTo(VehicleCargoList *, uint max_move, MoveToAction mta, CargoPayment *payment, uint data);