/*  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
    ========
    Starship (low-level) Artificial Intelligence class
*/

#include "StarshipAI.h"

#include <cstdint>

#include "StarshipTacticalAI.h"
#include "Ship.h"
#include "ShipDesign.h"
#include "Element.h"
#include "Mission.h"
#include "Instruction.h"
#include "RadioMessage.h"
#include "Contact.h"
#include "WeaponGroup.h"
#include "Drive.h"
#include "Sim.h"
#include "StarSystem.h"
#include "FlightComp.h"
#include "Farcaster.h"
#include "QuantumDrive.h"
#include "Clock.h"
#include "ContentBundle.h"
#include "Random.h"

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

StarshipAI::StarshipAI(SimObject* s)
: ShipAI(s), sub_select_time(0), subtarget(0), tgt_point_defense(false)
{
    ai_type = STARSHIP;

    // signifies this ship is a dead hulk:
    if (ship && ship->Design()->auto_roll < 0) {
        Point torque(rand()-16000, rand()-16000, rand()-16000);
        torque.Normalize();
        torque *= ship->Mass() / 10;

        ship->SetFLCSMode(0);
        if (ship->GetFLCS())
        ship->GetFLCS()->PowerOff();

        ship->ApplyTorque(torque);
        ship->SetVelocity(RandomDirection() * Random(20, 50));

        for (int i = 0; i < 64; i++) {
            Weapon* w = ship->GetWeaponByIndex(i+1);
            if (w)
            w->DrainPower(0);
            else
            break;
        }
    }

    else {
        tactical = new StarshipTacticalAI(this);
    }

    sub_select_time      = Clock::GetInstance()->GameTime() + static_cast<std::uint32_t>(Random(0, 2000));
    point_defense_time   = sub_select_time;
}


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

StarshipAI::~StarshipAI()
{ }

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

void
StarshipAI::FindObjective()
{
    distance = 0;

    int   order = ship->GetRadioOrders()->Action();

    if (order == RadioMessage::QUANTUM_TO ||
            order == RadioMessage::FARCAST_TO) {

        FindObjectiveQuantum();
        objective = Transform(obj_w);
        return;
    }

    bool  hold  = order == RadioMessage::WEP_HOLD ||
    order == RadioMessage::FORM_UP;

    bool  form  = hold                  ||
    (!order && !target)   ||
    (farcaster);

    // if not the element leader, stay in formation:
    if (form && element_index > 1) {
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.formation"));

        if (navpt && navpt->Action() == Instruction::LAUNCH) {
            FindObjectiveNavPoint();
        }
        else {
            navpt = 0;
            FindObjectiveFormation();
        }

        // transform into camera coords:
        objective = Transform(obj_w);
        return;
    }

    // under orders?
    bool   directed      = false;
    double threat_level  = 0;
    double support_level = 1;
    Ship*  ward          = ship->GetWard();

    if (tactical) {
        directed      = (tactical->RulesOfEngagement() == TacticalAI::DIRECTED);
        threat_level  = tactical->ThreatLevel();
        support_level = tactical->SupportLevel();
    }

    // threat processing:
    if (hold || !directed && threat_level >= 2*support_level) {

        // seek support:
        if (support) {
            double d_support = Point(support->Location() - ship->Location()).length();
            if (d_support > 35e3) {
                ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.regroup"));
                FindObjectiveTarget(support);
                objective = Transform(obj_w);
                return;
            }
        }

        // run away:
        else if (threat && threat != target) {
            ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.retreat"));
            obj_w = ship->Location() + Point(ship->Location() - threat->Location()) * 100;
            objective = Transform(obj_w);
            return;
        }
    }

    // weapons hold:
    if (hold) {
        if (navpt) {
            ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.seek-navpt"));
            FindObjectiveNavPoint();
        }

        else if (patrol) {
            ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.patrol"));
            FindObjectivePatrol();
        }

        else {
            ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.holding"));
            objective = Point();
        }
    }

    // normal processing:
    else if (target) {
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.seek-target"));
        FindObjectiveTarget(target);
    }

    else if (patrol) {
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.patrol"));
        FindObjectivePatrol();
    }

    else if (ward) {
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.seek-ward"));
        FindObjectiveFormation();
    }

    else if (navpt) {
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.seek-navpt"));
        FindObjectiveNavPoint();
    }

    else if (rumor) {
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.search"));
        FindObjectiveTarget(rumor);
    }

    else {
        objective = Point();
    }

    // transform into camera coords:
    objective = Transform(obj_w);
}

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

void
StarshipAI::Navigator()
{
    // signifies this ship is a dead hulk:
    if (ship && ship->Design()->auto_roll < 0) {
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.dead"));
        return;
    }

    accumulator.Clear();
    magnitude = 0;

    hold = false;
    if ((ship->GetElement() && ship->GetElement()->GetHoldTime() > 0) ||
            (navpt && navpt->Status() == Instruction::COMPLETE && navpt->HoldTime() > 0))
    hold = true;

    ship->SetFLCSMode(Ship::FLCS_HELM);

    if (!ship->GetDirectorInfo()) {
        if (target)
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.seek-target"));
        else if (ship->GetWard())
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.seek-ward"));
        else
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.patrol"));
    }

    if (farcaster && distance < 25e3) {
        accumulator = SeekTarget();
    }
    else {
        accumulator = AvoidCollision();

        if (!other && !hold)
        accumulator = SeekTarget();
    }

    HelmControl();
    ThrottleControl();
    FireControl();
    AdjustDefenses();
}

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

void
StarshipAI::HelmControl()
{
    // signifies this ship is a dead hulk:
    if (ship && ship->Design()->auto_roll < 0) {
        return;
    }

    double trans_x          = 0;
    double trans_y          = 0;
    double trans_z          = 0;

    bool   station_keeping  = distance < 0;

    if (station_keeping) {
        accumulator.brake = 1;
        accumulator.stop  = 1;

        ship->SetHelmPitch(0);
    }

    else {
        Element* elem = ship->GetElement();

        Ship* ward     = ship->GetWard();
        Ship* s_threat = 0;
        if (threat && threat->Class() >= ship->Class())
        s_threat = threat;

        if (other || target || ward || s_threat || navpt || patrol || farcaster || element_index > 1) {
            ship->SetHelmHeading(accumulator.yaw);

            if (elem->Type() == Mission::FLIGHT_OPS) {
                ship->SetHelmPitch(0);

                if (ship->NumInbound() > 0) {
                    ship->SetHelmHeading(ship->CompassHeading());
                }
            }

            else if (accumulator.pitch > 60*DEGREES) {
                ship->SetHelmPitch(60*DEGREES);
            }

            else if (accumulator.pitch < -60*DEGREES) {
                ship->SetHelmPitch(-60*DEGREES);
            }

            else {
                ship->SetHelmPitch(accumulator.pitch);
            }

        }
        else {
            ship->SetHelmPitch(0);
        }
    }

    ship->SetTransX(trans_x);
    ship->SetTransY(trans_y);
    ship->SetTransZ(trans_z);

    ship->ExecFLCSFrame();
}

void
StarshipAI::ThrottleControl()
{
    // signifies this ship is a dead hulk:
    if (ship && ship->Design()->auto_roll < 0) {
        return;
    }

    // station keeping:

    if (distance < 0) {
        old_throttle = 0;
        throttle     = 0;

        ship->SetThrottle(0);

        if (ship->GetFLCS())
        ship->GetFLCS()->FullStop();

        return;
    }

    // normal throttle processing:

    double   ship_speed  = ship->Velocity() * ship->Heading();
    double   brakes      = 0;
    Ship*    ward        = ship->GetWard();
    Ship*    s_threat    = 0;

    if (threat && threat->Class() >= ship->Class())
    s_threat = threat;

    if (target || s_threat) {  // target pursuit, or retreat
        throttle = 100;

        if (target && distance < 50e3) {
            double closing_speed = ship_speed;

            if (target) {
                Point delta = target->Location() - ship->Location();
                delta.Normalize();

                closing_speed = ship->Velocity() * delta;
            }

            if (closing_speed > 300) {
                throttle = 30;
                brakes   = 0.25;
            }
        }

        throttle *= (1 - accumulator.brake);

        if (throttle < 1 && ship->GetFLCS() != 0)
        ship->GetFLCS()->FullStop();
    }

    else if (ward) {           // escort, match speed of ward
        double speed = ward->Velocity().length();
        throttle = old_throttle;

        if (speed == 0) {
            double d = (ship->Location() - ward->Location()).length();

            if (d > 30e3)
            speed = (d - 30e3) / 100;
        }

        if (speed > 0) {
            if (ship_speed > speed) {
                throttle = old_throttle - 1;
                brakes   = 0.2;
            }
            else if (ship_speed < speed - 10) {
                throttle =  old_throttle + 1;
            }
        }
        else {
            throttle = 0;
            brakes   = 0.5;
        }
    }

    else if (patrol || farcaster) {  // seek patrol point
        throttle = 100;

        if (distance < 10 * ship_speed) {
            if (ship->Velocity().length() > 200)
            throttle = 5;
            else
            throttle = 50;
        }
    }

    else if (navpt) {          // lead only, get speed from navpt
        double speed = navpt->Speed();
        throttle = old_throttle;

        if (hold) {
            throttle = 0;
            brakes   = 1;
        }

        else {
            if (speed <= 0)
            speed = 300;

            if (ship_speed > speed) {
                if (throttle > 0 && old_throttle > 1)
                throttle = old_throttle - 1;

                brakes   = 0.25;
            }
            else if (ship_speed < speed - 10) {
                throttle =  old_throttle + 1;
            }
        }
    }

    else if (element_index > 1) { // wingman
        Ship*  lead = ship->GetElement()->GetShip(1);
        double lv = lead->Velocity().length();
        double sv = ship_speed;
        double dv = lv-sv;
        double dt = 0;

        if (dv > 0)       dt = dv * 1e-2 * seconds;
        else if (dv < 0)  dt = dv * 1e-2 * seconds;

        throttle = old_throttle + dt;
    }

    else {
        throttle = 0;
    }

    old_throttle = throttle;
    ship->SetThrottle(throttle);

    if (ship_speed > 1 && brakes > 0)
    ship->SetTransY(-brakes * ship->Design()->trans_y);

    else if (throttle > 10 && (ship->GetEMCON() < 2 || ship->GetFuelLevel() < 10))
    ship->SetTransY(ship->Design()->trans_y);
}

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

Steer
StarshipAI::SeekTarget()
{
    if (navpt) {
        SimRegion*     self_rgn = ship->GetRegion();
        SimRegion*     nav_rgn  = navpt->Region();
        QuantumDrive*  qdrive   = ship->GetQuantumDrive();

        if (self_rgn && !nav_rgn) {
            nav_rgn = self_rgn;
            navpt->SetRegion(nav_rgn);
        }

        bool use_farcaster      = self_rgn != nav_rgn &&
        (navpt->Farcast() ||
        !qdrive ||
        !qdrive->IsPowerOn() ||
        qdrive->Status() < System::DEGRADED
        );

        if (use_farcaster) {
            if (!farcaster) {
                ListIter<Ship> s = self_rgn->Ships();
                while (++s && !farcaster) {
                    if (s->GetFarcaster()) {
                        const Ship* dest = s->GetFarcaster()->GetDest();
                        if (dest && dest->GetRegion() == nav_rgn) {
                            farcaster = s->GetFarcaster();
                        }
                    }
                }
            }

            if (farcaster) {
                if (farcaster->GetShip()->GetRegion() != self_rgn)
                farcaster = farcaster->GetDest()->GetFarcaster();

                obj_w = farcaster->EndPoint();
                distance = Point(obj_w - ship->Location()).length();

                if (distance < 1000)
                farcaster = 0;
            }
        }
        else if (self_rgn != nav_rgn) {
            QuantumDrive* q = ship->GetQuantumDrive();

            if (q) {
                if (q->ActiveState() == QuantumDrive::ACTIVE_READY) {
                    q->SetDestination(navpt->Region(), navpt->Location());
                    q->Engage();
                }
            }
        }
    }

    return ShipAI::SeekTarget();
}

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

Steer
StarshipAI::AvoidCollision()
{
    if (!ship || ship->Velocity().length() < 25)
    return Steer();

    return ShipAI::AvoidCollision();
}

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

void
StarshipAI::FireControl()
{
    // identify unknown contacts:
    if (identify) {
        if (fabs(ship->GetHelmHeading() - ship->CompassHeading()) < 10*DEGREES) {
            Contact* contact = ship->FindContact(target);

            if (contact && !contact->ActLock()) {
                if (!ship->GetProbe()) {
                    ship->LaunchProbe();
                }
            }
        }

        return;
    }

    // investigate last known location of enemy ship:
    if (rumor && !target && ship->GetProbeLauncher() && !ship->GetProbe()) {
        // is rumor in basket?
        Point rmr = Transform(rumor->Location());
        rmr.Normalize();

        double dx = fabs(rmr.x);
        double dy = fabs(rmr.y);

        if (dx < 10*DEGREES && dy < 10*DEGREES && rmr.z > 0) {
            ship->LaunchProbe();
        }
    }

    // Corvettes and Frigates are anti-air platforms.  They need to
    // target missile threats even when the threat is aimed at another
    // friendly ship.  Forward facing weapons must be on auto fire,
    // while lateral and aft facing weapons are set to point defense.

    if (ship->Class() == Ship::CORVETTE || ship->Class() == Ship::FRIGATE) {
        ListIter<WeaponGroup> iter = ship->Weapons();
        while (++iter) {
            WeaponGroup* group = iter.value();

            ListIter<Weapon> w_iter = group->GetWeapons();
            while (++w_iter) {
                Weapon* weapon = w_iter.value();

                double az = weapon->GetAzimuth();
                if (fabs(az) < 45*DEGREES) {
                    weapon->SetFiringOrders(Weapon::AUTO);
                    weapon->SetTarget(target, 0);
                }

                else {
                    weapon->SetFiringOrders(Weapon::POINT_DEFENSE);
                }
            }
        }
    }

    // All other starships are free to engage ship targets.  Weapon
    // fire control is managed by the type of weapon.

    else {
        System* subtgt = SelectSubtarget();

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

            if (weapon->GetDesign()->target_type & Ship::DROPSHIPS) {   // anti-air weapon?
                weapon->SetFiringOrders(Weapon::POINT_DEFENSE);
            }
            else if (weapon->IsDrone()) {                               // torpedoes
                weapon->SetFiringOrders(Weapon::MANUAL);
                weapon->SetTarget(target, 0);

                if (target && target->GetRegion() == ship->GetRegion()) {
                    Point  delta = target->Location() - ship->Location();
                    double range = delta.length();

                    if (range < weapon->GetDesign()->max_range * 0.9 &&
                            !AssessTargetPointDefense())
                    weapon->SetFiringOrders(Weapon::AUTO);

                    else if (range < weapon->GetDesign()->max_range * 0.5)
                    weapon->SetFiringOrders(Weapon::AUTO);
                }
            }
            else {                                                      // anti-ship weapon
                weapon->SetFiringOrders(Weapon::AUTO);
                weapon->SetTarget(target, subtgt);
                weapon->SetSweep(subtgt ? Weapon::SWEEP_NONE : Weapon::SWEEP_TIGHT);
            }
        }
    }
}

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

System*
StarshipAI::SelectSubtarget()
{
    if (Clock::GetInstance()->GameTime() - sub_select_time < 2345)
    return subtarget;

    subtarget = 0;

    if (!target || target->Type() != SimObject::SIM_SHIP || GetAILevel() < 1)
    return subtarget;

    Ship* tgt_ship = (Ship*) target;

    if (!tgt_ship->IsStarship())
    return subtarget;

    Weapon*  subtgt = 0;
    double   dist   = 50e3;
    Point    svec   = ship->Location() - tgt_ship->Location();

    sub_select_time = Clock::GetInstance()->GameTime();

    // first pass: turrets
    ListIter<WeaponGroup> g_iter = tgt_ship->Weapons();
    while (++g_iter) {
        WeaponGroup* g = g_iter.value();

        if (g->GetDesign() && g->GetDesign()->turret_model) {
            ListIter<Weapon> w_iter = g->GetWeapons();
            while (++w_iter) {
                Weapon*  w     = w_iter.value();

                if (w->Availability() < 35)
                continue;

                if (w->GetAimVector() * svec < 0)
                continue;

                if (w->GetTurret()) {
                    Point    tloc  = w->GetTurret()->Location();
                    Point    delta = tloc - ship->Location();
                    double   dlen  = delta.length();

                    if (dlen < dist) {
                        subtgt = w;
                        dist   = dlen;
                    }
                }
            }
        }
    }

    // second pass: major weapons
    if (!subtgt) {
        g_iter.reset();
        while (++g_iter) {
            WeaponGroup* g = g_iter.value();

            if (g->GetDesign() && !g->GetDesign()->turret_model) {
                ListIter<Weapon> w_iter = g->GetWeapons();
                while (++w_iter) {
                    Weapon*  w     = w_iter.value();

                    if (w->Availability() < 35)
                    continue;

                    if (w->GetAimVector() * svec < 0)
                    continue;

                    Point    tloc  = w->MountLocation();
                    Point    delta = tloc - ship->Location();
                    double   dlen  = delta.length();

                    if (dlen < dist) {
                        subtgt = w;
                        dist   = dlen;
                    }
                }
            }
        }
    }

    subtarget = subtgt;
    return subtarget;
}

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

bool
StarshipAI::AssessTargetPointDefense()
{
    if (Clock::GetInstance()->GameTime() - point_defense_time < 3500)
    return tgt_point_defense;

    tgt_point_defense = false;

    if (!target || target->Type() != SimObject::SIM_SHIP || GetAILevel() < 2)
    return tgt_point_defense;

    Ship* tgt_ship = (Ship*) target;

    if (!tgt_ship->IsStarship())
    return tgt_point_defense;

    Weapon*  subtgt = 0;
    Point    svec   = ship->Location() - tgt_ship->Location();

    point_defense_time = Clock::GetInstance()->GameTime();

    // first pass: turrets
    ListIter<WeaponGroup> g_iter = tgt_ship->Weapons();
    while (++g_iter && !tgt_point_defense) {
        WeaponGroup* g = g_iter.value();

        if (g->CanTarget(1)) {
            ListIter<Weapon> w_iter = g->GetWeapons();
            while (++w_iter && !tgt_point_defense) {
                Weapon* w = w_iter.value();

                if (w->Availability() > 35 && w->GetAimVector() * svec > 0)
                tgt_point_defense = true;
            }
        }
    }

    return tgt_point_defense;
}


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

Point
StarshipAI::Transform(const Point& point)
{
    return point - self->Location();
}

Steer
StarshipAI::Seek(const Point& point)
{
    // the point is in relative world coordinates
    //   x: distance east(-)  / west(+)
    //   y: altitude down(-)  / up(+)
    //   z: distance north(-) / south(+)

    Steer result;

    result.yaw   = atan2(point.x, point.z) + PI;

    double adjacent = sqrt(point.x*point.x + point.z*point.z);
    if (fabs(point.y) > ship->Radius() && adjacent > ship->Radius())
    result.pitch = atan(point.y / adjacent);

    if (!_finite(result.yaw))
    result.yaw = 0;

    if (!_finite(result.pitch))
    result.pitch = 0;

    return result;
}

Steer
StarshipAI::Flee(const Point& point)
{
    Steer result = Seek(point);
    result.yaw += PI;
    return result;
}

Steer
StarshipAI::Avoid(const Point& point, float radius)
{
    Steer result = Seek(point);

    if (point * ship->BeamLine() > 0)
    result.yaw -= PI/2;
    else
    result.yaw += PI/2;

    return result;
}