/**
* Copyright (C) 2002-2012 The FreeCol Team
*
* This file is part of FreeCol.
*
* FreeCol 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.
*
* FreeCol 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 FreeCol. If not, see <http://www.gnu.org/licenses/>.
*/
package net.sf.freecol.server.ai.mission;
import java.util.logging.Logger;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.XMLStreamWriter;
import net.sf.freecol.common.model.Ability;
import net.sf.freecol.common.model.Colony;
import net.sf.freecol.common.model.CombatModel;
import net.sf.freecol.common.model.FreeColGameObject;
import net.sf.freecol.common.model.IndianSettlement;
import net.sf.freecol.common.model.Location;
import net.sf.freecol.common.model.Map.Direction;
import net.sf.freecol.common.model.PathNode;
import net.sf.freecol.common.model.Player;
import net.sf.freecol.common.model.Settlement;
import net.sf.freecol.common.model.Tension;
import net.sf.freecol.common.model.Tile;
import net.sf.freecol.common.model.Unit;
import net.sf.freecol.common.model.pathfinding.CostDeciders;
import net.sf.freecol.common.model.pathfinding.GoalDecider;
import net.sf.freecol.server.ai.AIMain;
import net.sf.freecol.server.ai.AIMessage;
import net.sf.freecol.server.ai.AIUnit;
/**
* Mission for attacking a specific target, be it a Unit or a Settlement.
*/
public class UnitSeekAndDestroyMission extends Mission {
private static final Logger logger = Logger.getLogger(UnitSeekAndDestroyMission.class.getName());
private static final String tag = "AI seek+destroyer";
/**
* The object we are trying to destroy. This can be a
* either <code>Settlement</code> or a <code>Unit</code>.
*/
private Location target;
/**
* Creates a mission for the given <code>AIUnit</code>.
*
* @param aiMain The main AI-object.
* @param aiUnit The <code>AIUnit</code> this mission
* is created for.
* @param target The object we are trying to destroy. This can be either a
* <code>Settlement</code> or a <code>Unit</code>.
*/
public UnitSeekAndDestroyMission(AIMain aiMain, AIUnit aiUnit,
Location target) {
super(aiMain, aiUnit);
if (!(target instanceof Unit || target instanceof Settlement)) {
throw new IllegalArgumentException("Invalid seek+destroy target: "
+ target);
}
this.target = target;
logger.finest(tag + " begins with target " + target + ": " + this);
uninitialized = false;
}
/**
* Creates a new <code>UnitSeekAndDestroyMission</code> and reads
* the given element.
*
* @param aiMain The main AI-object.
* @param in The input stream containing the XML.
* @throws XMLStreamException if a problem was encountered
* during parsing.
* @see net.sf.freecol.server.ai.AIObject#readFromXML
*/
public UnitSeekAndDestroyMission(AIMain aiMain, XMLStreamReader in)
throws XMLStreamException {
super(aiMain);
readFromXML(in);
uninitialized = getAIUnit() == null;
}
/**
* Sets a new mission target.
*
* @param target The new target <code>Location</code>.
*/
public void setTarget(Location target) {
removeTransportable("retargeted");
this.target = target;
}
/**
* Extract a valid target for this mission from a path.
*
* @param aiUnit The <code>AIUnit</code> to perform the mission.
* @param path A <code>PathNode</code> to extract a target from.
* @return A target for this mission, or null if none found.
*/
public static Location extractTarget(AIUnit aiUnit, PathNode path) {
final Location loc = (path == null) ? null
: path.getLastNode().getLocation();
Tile t;
Unit u;
return (loc == null || aiUnit == null || aiUnit.getUnit() == null)
? null
: (invalidReason(aiUnit, loc.getSettlement()) == null)
? loc.getSettlement()
: ((t = loc.getTile()) != null
&& invalidReason(aiUnit,
u = t.getDefendingUnit(aiUnit.getUnit())) == null)
? u
: null;
}
/**
* Gets a <code>GoalDecider</code> for finding the best colony
* <code>Tile</code>, optionally falling back to the nearest colony.
*
* @param aiUnit The <code>AIUnit</code> that is searching.
* @param deferOK Not used in this mission.
* @return A suitable <code>GoalDecider</code>.
*/
private static GoalDecider getGoalDecider(final AIUnit aiUnit,
boolean deferOK) {
return new GoalDecider() {
private PathNode bestPath = null;
private int bestValue = 0;
public PathNode getGoal() { return bestPath; }
public boolean hasSubGoals() { return true; }
public boolean check(Unit u, PathNode path) {
int value = scorePath(aiUnit, path);
if (bestValue < value) {
bestValue = value;
bestPath = path;
return true;
}
return false;
}
};
}
/**
* Scores a potential attack on a settlement.
*
* Do not cheat and look inside the settlement.
* Just use visible facts about it.
*
* TODO: if we are the REF and there is a significant Tory
* population inside, assume traitors have briefed us.
*
* @param aiUnit The <code>AIUnit</code> to do the mission.
* @param path The <code>PathNode</code> to take to the settlement.
* @param settlement The <code>Settlement</code> to attack.
* @return A score of the desirability of the mission.
*/
private static int scoreSettlementPath(AIUnit aiUnit, PathNode path,
Settlement settlement) {
if (invalidSettlementReason(aiUnit, settlement) != null) {
return Integer.MIN_VALUE;
}
final Unit unit = aiUnit.getUnit();
final CombatModel combatModel = unit.getGame().getCombatModel();
int value = 1020;
value -= path.getTotalTurns() * 100;
final float off = combatModel.getOffencePower(unit, settlement);
value += off * 50;
if (settlement instanceof Colony) {
// Favour high population (more loot:-).
Colony colony = (Colony) settlement;
value += 50 * colony.getUnitCount();
if (colony.hasStockade()) { // Avoid fortifications.
value -= 200 * colony.getStockade().getLevel();
}
} else if (settlement instanceof IndianSettlement) {
// Favour the most hostile settlements
IndianSettlement is = (IndianSettlement) settlement;
Tension tension = is.getAlarm(unit.getOwner());
if (tension != null) value += tension.getValue() / 2;
}
return value;
}
/**
* Scores a potential attack on a unit.
*
* @param aiUnit The <code>AIUnit</code> to do the mission.
* @param path The <code>PathNode</code> to take to the settlement.
* @param defender The <code>Unit</code> to attack.
* @return A score of the desirability of the mission.
*/
private static int scoreUnitPath(AIUnit aiUnit, PathNode path,
Unit defender) {
if (invalidUnitReason(aiUnit, defender) != null) {
return Integer.MIN_VALUE;
}
final Unit unit = aiUnit.getUnit();
final Tile tile = path.getLastNode().getTile();
final int turns = path.getTotalTurns();
final CombatModel combatModel = unit.getGame().getCombatModel();
final float off = combatModel.getOffencePower(unit, defender);
final float def = combatModel.getDefencePower(unit, defender);
if (tile == null || off <= 0) return Integer.MIN_VALUE;
int value = 1020 - turns * 100;
value += 100 * (off - def);
// Add a big bonus for treasure trains on the tile.
// Do not cheat and look at the value.
for (Unit u : tile.getUnitList()) {
if (u.canCarryTreasure() && u.getTreasureAmount() > 0) {
value += 1000;
break;
}
}
if (defender.isNaval()) {
if (tile.isLand()) value += 500; // Easy win
} else {
if (defender.hasAbility(Ability.EXPERT_SOLDIER)
&& !defender.isArmed()) value += 100;
}
return value;
}
/**
* Evaluate a potential seek and destroy mission for a given unit
* to a given tile.
*
* @param aiUnit The <code>AIUnit</code> to do the mission.
* @param path A <code>PathNode</code> to take to the target.
* @return A score for the proposed mission.
*/
public static int scorePath(AIUnit aiUnit, PathNode path) {
Location loc = extractTarget(aiUnit, path);
return (loc instanceof Settlement)
? scoreSettlementPath(aiUnit, path, (Settlement)loc)
: (loc instanceof Unit)
? scoreUnitPath(aiUnit, path, (Unit)loc)
: Integer.MIN_VALUE;
}
/**
* Finds a suitable seek-and-destroy target path for an AI unit.
*
* @param aiUnit The <code>AIUnit</code> to find a target for.
* @param range An upper bound on the number of moves.
* @return A path to the target, or null if none found.
*/
public static PathNode findTargetPath(AIUnit aiUnit, int range) {
if (invalidAIUnitReason(aiUnit) != null) return null;
final Unit unit = aiUnit.getUnit();
final Tile startTile = unit.getPathStartTile();
if (startTile == null) return null;
// Can the unit legally reach a valid target from where it
// currently is?
return unit.search(startTile, getGoalDecider(aiUnit, false),
CostDeciders.avoidIllegal(),
range, unit.getCarrier());
}
/**
* Finds a suitable seek-and-destroy target for an AI unit.
*
* @param aiUnit The <code>AIUnit</code> to find a target for.
* @param range An upper bound on the number of moves.
* @return A suitable target, or null if none found.
*/
public static Location findTarget(AIUnit aiUnit, int range) {
PathNode path = findTargetPath(aiUnit, range);
return (path != null) ? extractTarget(aiUnit, path)
: null;
}
// Fake Transportable interface
/**
* Gets the transport destination for units with this mission.
*
* @return The destination for this <code>Transportable</code>.
*/
@Override
public Location getTransportDestination() {
return (getTarget() == null
|| !shouldTakeTransportToTile(getTarget().getTile())) ? null
: getTarget();
}
// Mission interface
/**
* Gets the target of this mission.
*
* @return The mission target.
*/
public Location getTarget() {
return target;
}
/**
* Why would a UnitSeekAndDestroyMission be invalid with the given unit.
*
* @param aiUnit The <code>AIUnit</code> to test.
* @return A reason why the mission would be invalid, or null if
* none found.
*/
private static String invalidMissionReason(AIUnit aiUnit) {
String reason = invalidAIUnitReason(aiUnit);
return (reason != null)
? reason
: (!aiUnit.getUnit().isOffensiveUnit())
? Mission.UNITNOTOFFENSIVE
: (aiUnit.getUnit().hasAbility("model.ability.scoutIndianSettlement"))
? "scouts-should-not-seek-and-destroy"
: null;
}
/**
* Why would a UnitSeekAndDestroyMission be invalid with the given unit
* and settlement.
*
* @param aiUnit The <code>AIUnit</code> to seek-and-destroy with.
* @param settlement The <code>Settlement</code> to test.
* @return A reason why the mission would be invalid, or null if
* none found.
*/
private static String invalidSettlementReason(AIUnit aiUnit,
Settlement settlement) {
String reason = invalidTargetReason(settlement);
if (reason != null) return reason;
final Unit unit = aiUnit.getUnit();
return (unit.isNaval())
? "unit-is-naval"
: (settlement.getOwner() == unit.getOwner())
? Mission.TARGETOWNERSHIP
: invalidAttackReason(aiUnit, settlement.getOwner());
}
/**
* Why would a UnitSeekAndDestroyMission be invalid with the given unit
* and target unit.
*
* @param aiUnit The <code>AIUnit</code> to seek-and-destroy with.
* @param unit The target <code>Unit</code> to test.
* @return A reason why the mission would be invalid, or null if
* none found.
*/
private static String invalidUnitReason(AIUnit aiUnit, Unit unit) {
String reason = invalidTargetReason(unit);
if (reason != null) return reason;
final Tile tile = unit.getTile();
return (tile == null)
? "target-not-on-map"
: (aiUnit.getUnit().getOwner() == unit.getOwner())
? Mission.TARGETOWNERSHIP
: (tile.getSettlement() != null)
? "target-in-settlement"
: (!aiUnit.getUnit().isTileAccessible(tile))
? "target-incompatible"
: invalidAttackReason(aiUnit, unit.getOwner());
}
/**
* Why is this mission invalid?
*
* @return A reason for mission invalidity, or null if none found.
*/
public String invalidReason() {
return invalidReason(getAIUnit(), getTarget());
}
/**
* Why would this mission be invalid with the given AI unit?
*
* @param aiUnit The <code>AIUnit</code> to check.
* @return A reason for mission invalidity, or null if none found.
*/
public static String invalidReason(AIUnit aiUnit) {
return invalidMissionReason(aiUnit);
}
/**
* Why would this mission be invalid with the given AI unit and location?
*
* @param aiUnit The <code>AIUnit</code> to check.
* @param loc The <code>Location</code> to check.
* @return A reason for invalidity, or null if none found.
*/
public static String invalidReason(AIUnit aiUnit, Location loc) {
String reason = invalidMissionReason(aiUnit);
return (reason != null)
? reason
: (loc instanceof Settlement)
? invalidSettlementReason(aiUnit, (Settlement)loc)
: (loc instanceof Unit)
? invalidUnitReason(aiUnit, (Unit)loc)
: Mission.TARGETINVALID;
}
// Not a one-time mission, omit isOneTime().
/**
* Performs the mission.
*
* Check for a target-of-opportunity within one turn and hit that
* if possible. Otherwise, just continue on towards the real
* target.
*/
@Override
public void doMission() {
String reason = invalidReason();
if (isTargetReason(reason)) {
setTarget(null);
} else if (reason != null) {
logger.finest(tag + " broken(" + reason + "): " + this);
return;
}
// Is there a target-of-opportunity?
final AIUnit aiUnit = getAIUnit();
final Unit unit = getUnit();
Location nearbyTarget = findTarget(aiUnit, 1);
if (nearbyTarget != null) {
if (getTarget() == null) {
logger.finest(tag + " retargeted " + nearbyTarget
+ ": " + this);
setTarget(nearbyTarget);
nearbyTarget = null;
} else if (nearbyTarget == target) {
nearbyTarget = null;
} else {
logger.finest(tag + " found target-of-opportunity "
+ nearbyTarget + ": " + this);
}
} else if (reason != null) {
logger.finest(tag + " " + reason + ": " + this);
return;
}
// Go to the target.
Location currentTarget = (nearbyTarget != null) ? nearbyTarget
: getTarget();
// Note avoiding other targets by choice of cost decider.
Unit.MoveType mt = travelToTarget(tag, currentTarget,
CostDeciders.avoidSettlementsAndBlockingUnits());
switch (mt) {
case MOVE_NO_MOVES: case MOVE_ILLEGAL:
break;
case ATTACK_UNIT: case ATTACK_SETTLEMENT:
Tile unitTile = unit.getTile();
Settlement settlement = unitTile.getSettlement();
if (settlement != null && settlement.getUnitCount() < 2) {
// Do not risk attacking out of a settlement that
// might collapse. Defend instead.
aiUnit.setMission(new DefendSettlementMission(getAIMain(),
aiUnit, settlement));
return;
}
Direction dirn = unitTile.getDirection(currentTarget.getTile());
if (dirn == null) {
throw new IllegalStateException("No direction " + unitTile
+ " to " + currentTarget.getTile());
}
logger.finest(tag + " attacking " + currentTarget
+ ": " + this);
AIMessage.askAttack(aiUnit, dirn);
break;
default:
logger.finest(tag + " unexpected move type: " + mt + ": " + this);
break;
}
}
// Serialization
/**
* Writes all of the <code>AIObject</code>s and other AI-related
* information to an XML-stream.
*
* @param out The target stream.
* @throws XMLStreamException if there are any problems writing to the
* stream.
*/
protected void toXMLImpl(XMLStreamWriter out) throws XMLStreamException {
toXML(out, getXMLElementTagName());
}
/**
* {@inheritDoc}
*/
@Override
protected void writeAttributes(XMLStreamWriter out)
throws XMLStreamException {
super.writeAttributes(out);
if (target != null) {
writeAttribute(out, "target", (FreeColGameObject)target);
}
}
/**
* {@inheritDoc}
*/
@Override
protected void readAttributes(XMLStreamReader in)
throws XMLStreamException {
super.readAttributes(in);
String str = in.getAttributeValue(null, "target");
target = (str == null) ? null : getGame().getFreeColLocation(str);
}
/**
* Returns the tag name of the root element representing this object.
*
* @return "unitSeekAndDestroyMission".
*/
public static String getXMLElementTagName() {
return "unitSeekAndDestroyMission";
}
}