/*  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
    ========
    Automatic Navigator Artificial Intelligence class
*/

#include "NavAI.h"
#include "TacticalAI.h"
#include "Instruction.h"
#include "NavSystem.h"
#include "QuantumDrive.h"
#include "Ship.h"
#include "ShipDesign.h"
#include "ShipCtrl.h"
#include "Drive.h"
#include "Farcaster.h"
#include "Shield.h"
#include "Sim.h"
#include "StarSystem.h"
#include "KeyMap.h"
#include "HUDView.h"
#include "HUDSounds.h"
#include "ContentBundle.h"

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

NavAI::NavAI(Ship* s)
: ShipAI(s), complete(false), brakes(0),
drop_state(0), quantum_state(0), farcaster(0), terrain_warning(false)
{
    seek_gain = 20;
    seek_damp = 0.55;

    delete tactical;
    tactical = 0;
}

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

NavAI::~NavAI()
{ }

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

void
NavAI::ExecFrame(double s)
{
    if (!ship) return;

    seconds = s;

    ship->SetDirectorInfo(" ");

    if (ship->GetFlightPhase() == Ship::TAKEOFF)
    takeoff = true;

    else if (takeoff && ship->MissionClock() > 10000)
    takeoff = false;

    FindObjective();
    Navigator();

    // watch for disconnect:
    if (ShipCtrl::Toggled(KEY_AUTO_NAV)) {
        NavSystem* navsys = ship->GetNavSystem();
        if (navsys) {
            HUDView::GetInstance()->SetHUDMode(HUDView::HUD_MODE_TAC);
            navsys->DisengageAutoNav();

            Sim* sim = Sim::GetSim();
            if (sim) {
                ship->SetControls(sim->GetControls());
                return;
            }
        }
    }

    static double time_til_change = 0.0;

    if (time_til_change < 0.001) {
        if (ship->GetShield()) {
            Shield* shield = ship->GetShield();
            double  level  = shield->GetPowerLevel();

            if (ShipCtrl::KeyDown(KEY_SHIELDS_FULL)) {
                HUDSounds::PlaySound(HUDSounds::SND_SHIELD_LEVEL);
                shield->SetPowerLevel(100);
                time_til_change = 0.5f;
            }

            else if (ShipCtrl::KeyDown(KEY_SHIELDS_ZERO)) {
                HUDSounds::PlaySound(HUDSounds::SND_SHIELD_LEVEL);
                shield->SetPowerLevel(0);
                time_til_change = 0.5f;
            }

            else if (ShipCtrl::KeyDown(KEY_SHIELDS_UP)) {
                if (level < 25)      level =  25;
                else if (level < 50) level =  50;
                else if (level < 75) level =  75;
                else                 level = 100;

                HUDSounds::PlaySound(HUDSounds::SND_SHIELD_LEVEL);
                shield->SetPowerLevel(level);
                time_til_change = 0.5f;
            }

            else if (ShipCtrl::KeyDown(KEY_SHIELDS_DOWN)) {
                if (level > 75)      level =  75;
                else if (level > 50) level =  50;
                else if (level > 25) level =  25;
                else                 level =   0;

                HUDSounds::PlaySound(HUDSounds::SND_SHIELD_LEVEL);
                shield->SetPowerLevel(level);
                time_til_change = 0.5f;
            }

        }
    }
    else {
        time_til_change -= seconds;
    }

    if (ShipCtrl::Toggled(KEY_DECOY))
    ship->FireDecoy();

    if (ShipCtrl::Toggled(KEY_LAUNCH_PROBE))
    ship->LaunchProbe();

    if (ShipCtrl::Toggled(KEY_GEAR_TOGGLE))
    ship->ToggleGear();

    if (ShipCtrl::Toggled(KEY_NAVLIGHT_TOGGLE))
    ship->ToggleNavlights();

    if (drop_state < 0) {
        ship->DropOrbit();
        return;
    }

    if (drop_state > 0) {
        ship->MakeOrbit();
        return;
    }
}

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

void
NavAI::FindObjective()
{
    navpt    = 0;
    distance = 0;

    // runway takeoff:
    if (takeoff) {
        obj_w   = ship->Location()   + ship->Heading() * 10e3;
        obj_w.y = ship->Location().y + 2e3;

        // transform into camera coords:
        objective = Transform(obj_w);
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.takeoff"));
        return;
    }

    // PART I: Find next NavPoint:
    if (ship->GetNavSystem())
    navpt = ship->GetNextNavPoint();

    complete = !navpt;
    if (complete) return;

    // PART II: Compute Objective from NavPoint:
    Point       npt = navpt->Location();
    Sim*        sim = Sim::GetSim();
    SimRegion*  self_rgn = ship->GetRegion();
    SimRegion*  nav_rgn = navpt->Region();

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

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

            obj_w = farcaster->EndPoint();
        }

        else {
            obj_w = npt.OtherHand();
        }

        // distance from self to navpt:
        distance = Point(obj_w - self->Location()).length();

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

        if (!ship->IsStarship())
        objective.Normalize();

        if (farcaster && distance < 1000)
        farcaster = 0;
    }

    // PART III: Deal with orbital transitions:
    else if (ship->IsDropship()) {
        if (nav_rgn->GetOrbitalRegion()->Primary() ==
                self_rgn->GetOrbitalRegion()->Primary()) {

            Point npt = nav_rgn->Location() - self_rgn->Location();
            obj_w = npt.OtherHand();

            // distance from self to navpt:
            distance = Point(obj_w - ship->Location()).length();

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

            if (nav_rgn->IsAirSpace()) {
                drop_state = -1;
            }
            else if (nav_rgn->IsOrbital()) {
                drop_state = 1;
            }
        }

        // PART IIIa: Deal with farcaster jumps:
        else if (nav_rgn->IsOrbital() && self_rgn->IsOrbital()) {
            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) {
                Point apt   = farcaster->ApproachPoint(0);
                Point npt   = farcaster->StartPoint();
                double r1   = (ship->Location() - npt).length();

                if (r1 > 50e3) {
                    obj_w     = apt;
                    distance  = r1;
                    objective = Transform(obj_w);
                }

                else {
                    double r2 = (ship->Location() - apt).length();
                    double r3 = (npt - apt).length();

                    if (r1+r2 < 1.2*r3) {
                        obj_w     = npt;
                        distance  = r1;
                        objective = Transform(obj_w);
                    }
                    else {
                        obj_w     = apt;
                        distance  = r2;
                        objective = Transform(obj_w);
                    }
                }
            }
        }
    }

    // PART IV: Deal with quantum jumps:
    else if (ship->IsStarship()) {
        quantum_state = 1;

        Point npt = nav_rgn->Location() + navpt->Location();
        npt -= self_rgn->Location();
        obj_w = npt.OtherHand();

        // distance from self to navpt:
        distance = Point(obj_w - ship->Location()).length();

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

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

void
NavAI::Navigator()
{
    accumulator.Clear();
    magnitude = 0;
    brakes    = 0;
    hold      = false;

    if (navpt) {
        if (navpt->Status() == Instruction::COMPLETE && navpt->HoldTime() > 0) {
            ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.auto-hold"));
            hold = true;
        }
        else {
            ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.auto-nav"));
        }
    }
    else {
        ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.auto-stop"));
    }

    Accumulate(AvoidTerrain());
    Accumulate(AvoidCollision());

    if (!hold)
    accumulator = SeekTarget();

    HelmControl();
    ThrottleControl();
}

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

void
NavAI::HelmControl()
{
    // ----------------------------------------------------------
    // STARSHIP HELM MODE
    // ----------------------------------------------------------

    if (ship->IsStarship()) {
        ship->SetFLCSMode(Ship::FLCS_HELM);
        ship->SetHelmHeading(accumulator.yaw);

        if (accumulator.pitch > 45*DEGREES)
        ship->SetHelmPitch(45*DEGREES);

        else if (accumulator.pitch < -45*DEGREES)
        ship->SetHelmPitch(-45*DEGREES);

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

    // ----------------------------------------------------------
    // FIGHTER FLCS AUTO MODE
    // ----------------------------------------------------------

    else {
        ship->SetFLCSMode(Ship::FLCS_AUTO);

        // are we being asked to flee?
        if (fabs(accumulator.yaw) == 1.0 && accumulator.pitch == 0.0) {
            accumulator.pitch  = -0.7f;
            accumulator.yaw   *= 0.25f;
        }

        self->ApplyRoll((float) (accumulator.yaw * -0.4));
        self->ApplyYaw((float) (accumulator.yaw * 0.2));

        if (fabs(accumulator.yaw) > 0.5 && fabs(accumulator.pitch) < 0.1)
        accumulator.pitch -= 0.1f;

        if (accumulator.pitch != 0)
        self->ApplyPitch((float) accumulator.pitch);

        // if not turning, roll to orient with world coords:
        if (fabs(accumulator.yaw) < 0.1) {
            Point vrt = ((Camera*) &(self->Cam()))->vrt();
            double deflection = vrt.y;
            if (deflection != 0) {
                double theta = asin(deflection/vrt.length());
                self->ApplyRoll(-theta);
            }
        }

        if (!ship->IsAirborne() || ship->AltitudeAGL() > 100)
        ship->RaiseGear();
    }

    ship->SetTransX(0);
    ship->SetTransY(0);
    ship->SetTransZ(0);
    ship->ExecFLCSFrame();
}

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

void
NavAI::ThrottleControl()
{
    double ship_speed = ship->Velocity() * ship->Heading();
    bool   augmenter  = false;

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

    else if (navpt) {
        double speed      = navpt->Speed();

        if (speed < 10)
        speed = 250;

        throttle = 0;

        if (Ship::GetFlightModel() > 0) {
            if (ship_speed > speed + 10)
            throttle =  old_throttle - 0.25;

            else if (ship_speed < speed - 10)
            throttle =  old_throttle + 0.25;

            else
            throttle = old_throttle;
        }

        else {
            if (ship_speed > speed+5)
            brakes   = 0.25;

            else if (ship_speed < speed-5)
            throttle = 50;
        }
    }
    else {
        throttle = 0;
        brakes   = 0.25;
    }

    if (ship->IsAirborne() && ship->Class() < Ship::LCA) {
        if (ship_speed < 250) {
            throttle = 100;
            brakes   = 0;

            if (ship_speed < 200)
            augmenter = true;
        }

        else if (throttle < 20) {
            throttle = 20;
        }
    }

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

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

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

Steer
NavAI::SeekTarget()
{
    if (!ship)
    return Steer();

    if (takeoff)
    return Seek(objective);

    if (navpt) {
        if (quantum_state == 1) {
            QuantumDrive* q = ship->GetQuantumDrive();

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

                else if (q->ActiveState() == QuantumDrive::ACTIVE_POSTWARP) {
                    quantum_state = 0;
                }
            }
        }

        if (distance <  2 * self->Radius()) {
            ship->SetNavptStatus(navpt, Instruction::COMPLETE);

            return Steer();
        }
        else {
            return Seek(objective);
        }
    }

    return Steer();
}

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

void
NavAI::Disengage()
{
    throttle = 0;
}

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

Point
NavAI::Transform(const Point& point)
{
    if (ship && ship->IsStarship())
    return point - self->Location();

    return SteerAI::Transform(point);
}

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

    if (ship && ship->IsStarship()) {
        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 (_isnan(result.yaw))
        result.yaw = 0;

        if (_isnan(result.pitch))
        result.pitch = 0;

        return result;
    }

    return SteerAI::Seek(point);
}

Steer
NavAI::Flee(const Point& point)
{
    if (ship && ship->IsStarship()) {
        Steer result = Seek(point);
        result.yaw += PI;
        result.pitch *= -1;
        return result;
    }

    return SteerAI::Flee(point);
}

Steer
NavAI::Avoid(const Point& point, float radius)
{
    if (ship && ship->IsStarship()) {
        Steer result = Seek(point);

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

        return result;
    }

    return SteerAI::Avoid(point, radius);
}

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

Steer
NavAI::AvoidTerrain()
{
    Steer avoid;

    terrain_warning = false;

    if (!ship || !ship->GetRegion() || !ship->GetRegion()->IsActive() ||
            takeoff || (navpt && navpt->Action() == Instruction::LAUNCH))
    return avoid;

    if (ship->IsAirborne() && ship->GetFlightPhase() == Ship::ACTIVE) {
        // too low?
        if (ship->AltitudeAGL() < 1000) {
            terrain_warning = true;
            ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.too-low"));

            // way too low?
            if (ship->AltitudeAGL() < 750) {
                ship->SetDirectorInfo(ContentBundle::GetInstance()->GetText("ai.way-too-low"));
            }

            // where will we be?
            Point selfpt = ship->Location() + ship->Velocity() + Point(0, 10e3, 0);

            // transform into camera coords:
            Point obj = Transform(selfpt);

            // pull up!
            avoid = Seek(obj);
        }
    }

    return avoid;
}