/*  Starshatter: The Open Source Project
    Copyright (c) 2021-2024, Starshatter: The Open Source Project Contributors
    Copyright (c) 2011-2012, Starshatter OpenSource Distribution Contributors
    Copyright (c) 1997-2006, Destroyer Studios LLC.

    AUTHOR:       John DiCamillo


    OVERVIEW
    ========
    Fighter-specific mid-level (tactical) AI class
*/

#include "FighterTacticalAI.h"
#include "ShipAI.h"
#include "Ship.h"
#include "ShipDesign.h"
#include "Shot.h"
#include "Element.h"
#include "Instruction.h"
#include "RadioMessage.h"
#include "Sensor.h"
#include "Contact.h"
#include "WeaponGroup.h"
#include "Drive.h"
#include "Sim.h"
#include "StarSystem.h"

#include "Clock.h"
#include "ContentBundle.h"

// +----------------------------------------------------------------------+

const int WINCHESTER_FIGHTER = 0;
const int WINCHESTER_ASSAULT = 1;
const int WINCHESTER_STRIKE  = 2;
const int WINCHESTER_STATIC  = 3;

// +----------------------------------------------------------------------+

FighterTacticalAI::FighterTacticalAI(ShipAI* ai)
: TacticalAI(ai), secondary_selection_time(0)
{
    for (int i = 0; i < 4; i++)
    winchester[i] = false;

    ai_level = ai->GetAILevel();

    switch (ai_level) {
    default:
    case 2:  THREAT_REACTION_TIME =  1000; break;
    case 1:  THREAT_REACTION_TIME =  3000; break;
    case 0:  THREAT_REACTION_TIME =  6000; break;
    }
}


// +--------------------------------------------------------------------+

FighterTacticalAI::~FighterTacticalAI()
{ }

// +--------------------------------------------------------------------+

bool
FighterTacticalAI::CheckFlightPlan()
{
    navpt = ship->GetNextNavPoint();

    int order = Instruction::PATROL;
    roe       = FLEXIBLE;

    if (navpt) {
        order = navpt->Action();

        switch (order)  {
        case Instruction::LAUNCH:
        case Instruction::DOCK:
        case Instruction::RTB:     roe = NONE;
            break;

        case Instruction::VECTOR:
            roe = SELF_DEFENSIVE;
            if (element_index > 1)
            roe = DEFENSIVE;
            break;

        case Instruction::DEFEND:
        case Instruction::ESCORT:  roe = DEFENSIVE;
            break;

        case Instruction::INTERCEPT:
            if (element_index > 1)
            roe = DEFENSIVE;
            else
            roe = DIRECTED;
            break;

        case Instruction::RECON:
        case Instruction::STRIKE:
        case Instruction::ASSAULT: roe = DIRECTED;
            break;

        case Instruction::PATROL:
        case Instruction::SWEEP:   roe = FLEXIBLE;
            break;

        default: break;
        }

        if (order == Instruction::STRIKE) {
            ship->SetSensorMode(Sensor::GM);

            if (IsStrikeComplete(navpt)) {
                ship->SetNavptStatus(navpt, Instruction::COMPLETE);
            }
        }

        else if (order == Instruction::ASSAULT) {
            if (ship->GetSensorMode() == Sensor::GM)
            ship->SetSensorMode(Sensor::STD);

            if (IsStrikeComplete(navpt)) {
                ship->SetNavptStatus(navpt, Instruction::COMPLETE);
            }
        }

        else {
            if (ship->GetSensorMode() == Sensor::GM)
            ship->SetSensorMode(Sensor::STD);
        }
    }

    switch (roe) {
    case NONE:              ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.none"));            break;
    case SELF_DEFENSIVE:    ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.self-defensive"));  break;
    case DEFENSIVE:         ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.defensive"));       break;
    case DIRECTED:          ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.directed"));        break;
    case FLEXIBLE:          ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.flexible"));        break;
    default:                ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.default"));         break;
    }

    return (navpt != 0);
}

// +--------------------------------------------------------------------+

void
FighterTacticalAI::SelectTarget()
{
    TacticalAI::SelectTarget();

    SimObject* target = ship_ai->GetTarget();

    if (target && (target->Type() == SimObject::SIM_SHIP) &&
            (Clock::GetInstance()->GameTime() - secondary_selection_time) > THREAT_REACTION_TIME) {
        SelectSecondaryForTarget((Ship*) target);
        secondary_selection_time = Clock::GetInstance()->GameTime();
    }
}

// +--------------------------------------------------------------------+

void
FighterTacticalAI::SelectTargetDirected(Ship* tgt)
{
    Ship* potential_target = tgt;

    if (!tgt) {
        // try to target one of the element's objectives
        // (if it shows up in the contact list)

        Element* elem = ship->GetElement();

        if (elem) {
            Instruction* objective = elem->GetTargetObjective();

            if (objective) {
                SimObject* obj_sim_obj = objective->GetTarget();
                Ship*      obj_tgt     = 0;

                if (obj_sim_obj && obj_sim_obj->Type() == SimObject::SIM_SHIP)
                obj_tgt = (Ship*) obj_sim_obj;

                if (obj_tgt && ship->FindContact(obj_tgt))
                potential_target = obj_tgt;
            }
        }
    }

    if (!CanTarget(potential_target))
    potential_target = 0;

    ship_ai->SetTarget(potential_target);
    SelectSecondaryForTarget(potential_target);
}

// +--------------------------------------------------------------------+

void
FighterTacticalAI::SelectTargetOpportunity()
{
    // NON-COMBATANTS do not pick targets of opportunity:
    if (ship->GetIFF() == 0)
    return;

    Ship* potential_target    = 0;
    Shot* current_shot_target = 0;

    // pick the closest combatant ship with a different IFF code:
    double target_dist = 1.0e15;
    double min_dist    = 5.0e3;

    // FIGHTERS are primarily anti-air platforms, but may
    // also attack smaller starships:

    Ship* ward = 0;
    if (element_index > 1)
    ward = ship->GetLeader();

    // commit range for patrol/sweep is 80 Km
    // (about 2 minutes for a fighter at max speed)
    if (roe == FLEXIBLE || roe == AGRESSIVE)
    target_dist = ship->Design()->commit_range;

    if (roe < FLEXIBLE)
    target_dist = 0.5 * ship->Design()->commit_range;

    int class_limit = Ship::LCA;

    if (ship->Class() == Ship::ATTACK)
    class_limit = Ship::DESTROYER;

    ListIter<Contact> c_iter = ship->ContactList();
    while (++c_iter) {
        Contact* contact = c_iter.value();
        Ship*    c_ship  = contact->GetShip();
        Shot*    c_shot  = contact->GetShot();
        int      c_iff   = contact->GetIFF(ship);
        bool     rogue   = false;

        if (c_ship)
        rogue = c_ship->IsRogue();

        if (!rogue && (c_iff <= 0 || c_iff == ship->GetIFF() || c_iff == 1000))
        continue;

        // reasonable target?
        if (c_ship && c_ship->Class() <= class_limit && !c_ship->InTransition()) {
            if (!rogue) {
                SimObject* ttgt = c_ship->GetTarget();

                // if we are self-defensive, is this contact engaging us?
                if (roe == SELF_DEFENSIVE && ttgt != ship)
                continue;

                // if we are defending, is this contact engaging us or our ward?
                if (roe == DEFENSIVE && ttgt != ship && ttgt != ward)
                continue;
            }

            // found an enemy, check distance:
            double dist = (ship->Location() - c_ship->Location()).length();

            if (dist < 0.75 * target_dist) {

                // if on patrol, check target distance from navpoint:
                if (roe == FLEXIBLE && navpt) {
                    double ndist = (navpt->Location().OtherHand() - c_ship->Location()).length();
                    if (ndist > 80e3)
                    continue;
                }

                potential_target = c_ship;
                target_dist = dist;
            }
        }

        else if (c_shot && c_shot->IsDrone()) {
            // found an enemy shot, do we have enough time to engage?
            if (c_shot->GetEta() < 10)
            continue;

            // found an enemy shot, check distance:
            double dist = (ship->Location() - c_shot->Location()).length();

            if (!current_shot_target) {
                current_shot_target = c_shot;
                target_dist = dist;
            }

            // is this shot a better target than the one we've found?
            else {
                Ship* ward = ship_ai->GetWard();

                if ((c_shot->IsTracking(ward) && !current_shot_target->IsTracking(ward)) ||
                        (dist < target_dist)) {
                    current_shot_target = c_shot;
                    target_dist = dist;
                }
            }
        }
    }

    if (current_shot_target) {
        ship_ai->SetTarget(current_shot_target);
    }
    else {
        ship_ai->SetTarget(potential_target);
        SelectSecondaryForTarget(potential_target);
    }
}

// +--------------------------------------------------------------------+

int
FighterTacticalAI::ListSecondariesForTarget(Ship* tgt, List<WeaponGroup>& weps)
{
    weps.clear();

    if (tgt) {
        ListIter<WeaponGroup> iter = ship->Weapons();
        while (++iter) {
            WeaponGroup* w = iter.value();

            if (w->Ammo() && w->CanTarget(tgt->Class()))
            weps.append(w);
        }
    }

    return weps.size();
}

void
FighterTacticalAI::SelectSecondaryForTarget(Ship* tgt)
{
    if (tgt) {
        int wix = WINCHESTER_FIGHTER;

        if (tgt->IsGroundUnit())      wix = WINCHESTER_STRIKE;
        else if (tgt->IsStatic())     wix = WINCHESTER_STATIC;
        else if (tgt->IsStarship())   wix = WINCHESTER_ASSAULT;

        WeaponGroup*      best = 0;
        List<WeaponGroup> weps;

        if (ListSecondariesForTarget(tgt, weps)) {
            winchester[wix] = false;

            // select best weapon for the job:
            double range       = (ship->Location() - tgt->Location()).length();
            double best_range  = 0;
            double best_damage = 0;

            ListIter<WeaponGroup> iter  = weps;
            while (++iter) {
                WeaponGroup* w = iter.value();

                if (!best) {
                    best = w;

                    WeaponDesign* d = best->GetDesign();
                    best_range  = d->max_range;
                    best_damage = d->damage * d->ripple_count;

                    if (best_range < range)
                    best = 0;
                }

                else {
                    WeaponDesign* d = w->GetDesign();
                    double w_range  = d->max_range;
                    double w_damage = d->damage * d->ripple_count;

                    if (w_range > range) {
                        if (w_range < best_range || w_damage > best_damage)
                        best = w;
                    }
                }
            }

            // now cycle weapons until you pick the best one:
            WeaponGroup* current_missile = ship->GetSecondaryGroup();

            if (current_missile && best && current_missile != best) {
                ship->CycleSecondary();
                WeaponGroup* m = ship->GetSecondaryGroup();

                while (m != current_missile && m != best) {
                    ship->CycleSecondary();
                    m = ship->GetSecondaryGroup();
                }
            }
        }

        else {
            winchester[wix] = true;

            // if we have NO weapons that can hit this target,
            // just drop it:

            Weapon* primary = ship->GetPrimary();
            if (!primary || !primary->CanTarget(tgt->Class())) {
                ship_ai->DropTarget(3);
                ship->DropTarget();
            }
        }

        if (tgt->IsGroundUnit())
        ship->SetSensorMode(Sensor::GM);

        else if (ship->GetSensorMode() == Sensor::GM)
        ship->SetSensorMode(Sensor::STD);
    }
}

// +--------------------------------------------------------------------+

void
FighterTacticalAI::FindFormationSlot(int formation)
{
    // find the formation delta:
    int s = element_index - 1;
    Point delta(5*s, 0, -5*s);

    // diamond:
    if (formation == Instruction::DIAMOND) {
        switch (element_index) {
        case 2:  delta = Point( 12, -1, -10); break;
        case 3:  delta = Point(-12, -1, -10); break;
        case 4:  delta = Point(  0, -2, -20); break;
        }
    }

    // spread:
    if (formation == Instruction::SPREAD) {
        switch (element_index) {
        case 2:  delta = Point( 15, 0, 0); break;
        case 3:  delta = Point(-15, 0, 0); break;
        case 4:  delta = Point(-30, 0, 0); break;
        }
    }

    // box:
    if (formation == Instruction::BOX) {
        switch (element_index) {
        case 2:  delta = Point(15,  0,   0); break;
        case 3:  delta = Point( 0, -2, -20); break;
        case 4:  delta = Point(15, -2, -20); break;
        }
    }

    // trail:
    if (formation == Instruction::TRAIL) {
        delta = Point(0, s, -20*s);
    }

    ship_ai->SetFormationDelta(delta * ship->Radius() * 2);
}

// +--------------------------------------------------------------------+

void
FighterTacticalAI::FindThreat()
{
    // pick the closest contact on Threat Warning System:
    Ship*       threat_ship          = 0;
    Shot*       threat_missile       = 0;
    double      threat_dist          = 1e9;

    ListIter<Contact> c_iter = ship->ContactList();

    while (++c_iter) {
        Contact* contact = c_iter.value();

        if (contact->Threat(ship) &&
                (Clock::GetInstance()->GameTime() - contact->AcquisitionTime()) > THREAT_REACTION_TIME) {

            double rng = contact->Range(ship);

            if (contact->GetShot()) {
                threat_missile = contact->GetShot();
            }

            else if (rng < threat_dist && contact->GetShip()) {
                Ship* candidate = contact->GetShip();

                if (candidate->InTransition())
                continue;

                if (candidate->IsStarship() && rng < 50e3) {
                    threat_ship = candidate;
                    threat_dist = rng;
                }

                else if (candidate->IsDropship() && rng < 25e3) {
                    threat_ship = candidate;
                    threat_dist = rng;
                }

                // static and ground units:
                else if (rng < 30e3) {
                    threat_ship = candidate;
                    threat_dist = rng;
                }
            }
        }
    }

    ship_ai->SetThreat(threat_ship);
    ship_ai->SetThreatMissile(threat_missile);
}

// +--------------------------------------------------------------------+

bool
FighterTacticalAI::IsStrikeComplete(Instruction* instr)
{
    // wingmen can not call a halt to a strike:
    if (!ship || element_index > 1)
    return false;

    // if there's nothing to shoot at, we must be done:
    if (!instr || !instr->GetTarget() || instr->GetTarget()->Life() == 0 ||
            instr->GetTarget()->Type() != SimObject::SIM_SHIP)
    return true;

    // break off strike only when ALL weapons are expended:
    // (remember to check all relevant wingmen)
    Element*    element = ship->GetElement();
    Ship*       target  = (Ship*) instr->GetTarget();

    if (!element)
    return true;

    for (int i = 0; i < element->NumShips(); i++) {
        Ship* s = element->GetShip(i+1);

        if (!s || s->Integrity() < 25) // || (s->Location() - target->Location()).length() > 250e3)
        continue;

        ListIter<WeaponGroup> g_iter = s->Weapons();
        while (++g_iter) {
            WeaponGroup* w = g_iter.value();

            if (w->Ammo() && w->CanTarget(target->Class())) {
                ListIter<Weapon> w_iter = w->GetWeapons();

                while (++w_iter) {
                    Weapon* weapon = w_iter.value();

                    if (weapon->Status() > System::CRITICAL)
                    return false;
                }
            }
        }
    }

    // still here?  we must be done!
    return true;
}