/*  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
    ========
    Integrated (Passive and Active) Sensor Package class implementation
*/

#include "Contact.h"

#include "Clock.h"
#include "Drone.h"
#include "Game.h"
#include "Sensor.h"
#include "Ship.h"
#include "Sim.h"
#include "WeaponDesign.h"

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

const int      DEFAULT_TRACK_UPDATE = 500; // milliseconds
const int      DEFAULT_TRACK_LENGTH =  20; // 10 seconds
const double   DEFAULT_TRACK_AGE    =  10; // 10 seconds
const double   SENSOR_THRESHOLD     = 0.25;

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

Contact::Contact()
: ship(0), shot(0), d_pas(0.0f), d_act(0.0f),
track(0), ntrack(0), time(0), track_time(0), probe(false)
{
    acquire_time = Clock::GetInstance()->GameTime();
}

Contact::Contact(Ship* s, float p, float a)
: ship(s), shot(0), d_pas(p), d_act(a),
track(0), ntrack(0), time(0), track_time(0), probe(false)
{
    acquire_time = Clock::GetInstance()->GameTime();
    Observe(ship);
}

Contact::Contact(Shot* s, float p, float a)
: ship(0), shot(s), d_pas(p), d_act(a),
track(0), ntrack(0), time(0), track_time(0), probe(false)
{
    acquire_time = Clock::GetInstance()->GameTime();
    Observe(shot);
}

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

Contact::~Contact()
{
    delete [] track;
}

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

int
Contact::operator == (const Contact& c) const
{
    if (ship)
    return ship == c.ship;

    else if (shot)
    return shot == c.shot;

    return 0;
}

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

bool
Contact::Update(SimObject* obj)
{
    if (obj == ship || obj == shot) {
        ship  = 0;
        shot  = 0;
        d_act = 0;
        d_pas = 0;

        ClearTrack();
    }

    return SimObserver::Update(obj);
}

const char*
Contact::GetObserverName() const
{
    static char name[128];

    if (ship)
        sprintf_s(name, "Contact Ship='%s'", ship->Name());
    else if (shot)
        sprintf_s(name, "Contact Shot='%s' %s", shot->Name(), shot->DesignName());
    else
        sprintf_s(name, "Contact (unknown)");

    return name;
}

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

double
Contact::Age() const
{
    double age = 0;

    if (!ship && !shot)
    return age;

    double seconds = (Clock::GetInstance()->GameTime() - time) / 1000.0;

    age = 1.0 - seconds/DEFAULT_TRACK_AGE;

    if (age < 0)
    age = 0;

    return age;
}

int
Contact::GetIFF(const Ship* observer) const
{
    int i = 0;

    if (ship) {
        i = ship->GetIFF();

        // if the contact is on our side or has locked us up,
        // we know whose side he's on.

        // Otherwise:
        if (i != observer->GetIFF() && !Threat(observer)) {
            if (d_pas < 2*SENSOR_THRESHOLD && d_act < SENSOR_THRESHOLD && !Visible(observer))
            i = -1000;   // indeterminate iff reading
        }
    }

    else if (shot && shot->Owner()) {
        i = shot->Owner()->GetIFF();
    }

    return i;
}

bool
Contact::ActLock() const
{
    return d_act >= SENSOR_THRESHOLD;
}

bool
Contact::PasLock() const
{
    return d_pas >= SENSOR_THRESHOLD;
}

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

void
Contact::GetBearing(const Ship* observer, double& az, double& el, double& rng) const
{
    // translate:
    Point targ_pt = loc - observer->Location();

    // rotate:
    const Camera* cam = &observer->Cam();
    double        tx  = targ_pt * cam->vrt();
    double        ty  = targ_pt * cam->vup();
    double        tz  = targ_pt * cam->vpn();

    // convert to spherical coords:
    rng = targ_pt.length();
    az  = asin(fabs(tx) / rng);
    el  = asin(fabs(ty) / rng);

    if (tx < 0) az = -az;
    if (ty < 0) el = -el;

    // correct az/el for back hemisphere:
    if (tz < 0) {
        if (az < 0) az = -PI - az;
        else        az =  PI - az;
    }
}

double
Contact::Range(const Ship* observer, double limit) const
{
    double r = Point(loc - observer->Location()).length();

    // if passive only, return approximate range:
    if (!ActLock()) {
        const int chunk = 25000;

        if (!PasLock()) {
            r = (int) limit;
        }

        else if (r <= chunk) {
            r = chunk;
        }

        else {
            int r1 = (int) (r + chunk/2) / chunk;
            r = r1 * chunk;
        }
    }

    return r;
}

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

bool
Contact::InFront(const Ship* observer) const
{
    // translate:
    Point targ_pt = loc - observer->Location();

    // rotate:
    const Camera* cam = &observer->Cam();
    double tz = targ_pt * cam->vpn();

    if (tz > 1.0)
    return true;

    return false;
}

bool
Contact::Threat(const Ship* observer) const
{
    bool threat = false;

    if (observer && observer->Life() != 0) {
        if (ship && ship->Life() != 0) {
            threat = (ship->GetIFF() &&
            ship->GetIFF() != observer->GetIFF() &&
            ship->GetEMCON() > 2 &&
            ship->IsTracking((Ship*) observer) &&
            ship->Weapons().size() > 0);

            if (threat && observer->GetIFF() == 0)
            threat = ship->GetIFF() > 1;
        }

        else if (shot) {
            threat = shot->IsTracking((Ship*) observer);

            if (!threat && shot->Design()->probe && shot->GetIFF() != observer->GetIFF()) {
                Point  probe_pt = shot->Location() - observer->Location();
                double prng     = probe_pt.length();

                threat = (prng < shot->Design()->lethal_radius);
            }
        }
    }

    return threat;
}

bool
Contact::Visible(const Ship* observer) const
{
    // translate:
    Point targ_pt = loc - observer->Location();
    double radius = 0;

    if (ship)
    radius = ship->Radius();

    else if (shot)
    radius = shot->Radius();

    // rotate:
    const Camera* cam = &observer->Cam();
    double        rng = targ_pt.length();

    return radius/rng > 0.002;
}

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

void
Contact::Reset()
{
    if (Game::GetInstance()->Paused()) return;

    float step_down = (float) (Clock::GetInstance()->Delta() / 10);

    if (d_pas > 0)
    d_pas -= step_down;

    if (d_act > 0)
    d_act -= step_down;
}

void
Contact::Merge(Contact* c)
{
    if (c->GetShip() == ship && c->GetShot() == shot) {
        if (c->d_pas > d_pas)
        d_pas = c->d_pas;

        if (c->d_act > d_act)
        d_act = c->d_act;
    }
}

void
Contact::ClearTrack()
{
    delete [] track;
    track = 0;
    ntrack = 0;
}

void
Contact::UpdateTrack()
{
    time = Clock::GetInstance()->GameTime();

    if (shot || (ship && ship->IsGroundUnit()))
    return;

    if (!track) {
        track = new Point[DEFAULT_TRACK_LENGTH];
        track[0] = loc;
        ntrack   = 1;
        track_time = time;
    }

    else if (time - track_time > DEFAULT_TRACK_UPDATE) {
        if (loc != track[0]) {
            for (int i = DEFAULT_TRACK_LENGTH-2; i >= 0; i--)
            track[i+1] = track[i];

            track[0] = loc;
            if (ntrack < DEFAULT_TRACK_LENGTH) ntrack++;
        }

        track_time = time;
    }
}

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

Point
Contact::TrackPoint(int i) const
{
    if (track && i < ntrack)
    return track[i];

    return Point();
}