// hud_rwy.cxx -- An instrument that renders a virtual runway on the HUD
//
// Written by Aaron Wilson & Phillip Merritt, Nov 2004.
//
// Copyright (C) 2004 Aaron Wilson, Aaron.I.Wilson@nasa.gov
// Copyright (C) 2004 Phillip Merritt, Phillip.M.Merritt@nasa.gov
//
// This program 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.
//
// This program 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 this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//

#include <simgear/compiler.h>

#include "hud.hxx"

#include <math.h>
#include <Main/globals.hxx>
#include <Scenery/scenery.hxx>
#include <Aircraft/aircraft.hxx>
#include <Environment/environment.hxx>
#include <Environment/environment_mgr.hxx>
#include <simgear/math/sg_geodesy.hxx>
#include <simgear/math/polar3d.hxx>
#include SG_GLU_H
#include <ATC/ATCutils.hxx>


// int x, int y, int width, int height, float scale_data, bool working)

runway_instr::runway_instr(const SGPropertyNode *node) :
    instr_item(
            node->getIntValue("x"),
            node->getIntValue("y"),
            node->getIntValue("width"),
            node->getIntValue("height"),
            NULL,
            node->getDoubleValue("scale"),
            0,
            node->getBoolValue("working", true)),
    arrowScale(node->getDoubleValue("arrow_scale", 1.0)),
    arrowRad(node->getDoubleValue("arrow_radius")),
    lnScale(node->getDoubleValue("line_scale", 1.0)),
    scaleDist(node->getDoubleValue("scale_dist_nm")),
    default_pitch(fgGetDouble("/sim/view[0]/config/pitch-pitch-deg", 0.0)),
    default_heading(fgGetDouble("/sim/view[0]/config/pitch-heading-deg", 0.0)),
    cockpit_view(globals->get_viewmgr()->get_view(0)),
    stippleOut(node->getIntValue("outer_stipple", 0xFFFF)),
    stippleCen(node->getIntValue("center_stipple", 0xFFFF)),
    drawIA(arrowScale > 0 ? true : false),
    drawIAAlways(arrowScale > 0 ? node->getBoolValue("arrow_always") : false)
{
    SG_LOG(SG_INPUT, SG_INFO, "Done reading runway instrument "
            << node->getStringValue("name", "[unnamed]"));

    view[0] = 0;
    view[1] = 0;
    view[2] = 640;
    view[3] = 480;

    center.x = view[2] >> 1;
    center.y = view[3] >> 1;

    location.left = center.x - (get_width() >> 1) + get_x();
    location.right = center.x + (get_width() >>1) + get_x();
    location.bottom = center.y - (get_height() >>1) + get_y();
    location.top = center.y + (get_height() >> 1) + get_y();
}



void runway_instr::draw()
{
    if (!is_broken() && get_active_runway(runway)) {
        glPushAttrib(GL_LINE_STIPPLE | GL_LINE_STIPPLE_PATTERN | GL_LINE_WIDTH);
        float modelView[4][4], projMat[4][4];
        bool anyLines;
        //Get the current view
        FGViewer* curr_view = globals->get_viewmgr()->get_current_view();
        int curr_view_id = globals->get_viewmgr()->get_current();
        double gpo = curr_view->getGoalPitchOffset_deg();
        double gho = curr_view->getGoalHeadingOffset_deg();
        double po = curr_view->getPitchOffset_deg();
        double ho = curr_view->getHeadingOffset_deg();

        double yaw = -(cockpit_view->getHeadingOffset_deg() - default_heading) * SG_DEGREES_TO_RADIANS;
        double pitch = (cockpit_view->getPitchOffset_deg() - default_pitch) * SG_DEGREES_TO_RADIANS;
        //double roll = fgGetDouble("/sim/view[0]/config/roll-offset-deg",0.0) //TODO: adjust for default roll offset
        double sPitch = sin(pitch), cPitch = cos(pitch),
               sYaw = sin(yaw), cYaw = cos(yaw);

        //Assuming that the "Cockpit View" is always at position zero!!!
        if (curr_view_id != 0) {
            globals->get_viewmgr()->set_view(0);
            globals->get_viewmgr()->copyToCurrent();
        }
        //Set the camera to the cockpit view to get the view of the runway from the cockpit
        ssgSetCamera((sgVec4 *)cockpit_view->get_VIEW());
        get_rwy_points(points3d);
        //Get the current project matrix
        ssgGetProjectionMatrix(projMat);
//        const sgVec4 *viewMat = globals->get_current_view()->get_VIEW();
        //Get the current model view matrix (cockpit view)
        ssgGetModelviewMatrix(modelView);
        //Create a rotation matrix to correct for any offsets (other than default offsets) to the model view matrix
        sgMat4 xy; //rotation about the Rxy, negate the sin's on Ry
        xy[0][0] = cYaw;         xy[1][0] = 0.0f;   xy[2][0] = -sYaw;        xy[3][0] = 0.0f;
        xy[0][1] = sPitch*-sYaw; xy[1][1] = cPitch; xy[2][1] = -sPitch*cYaw; xy[3][1] = 0.0f;
        xy[0][2] = cPitch*sYaw;  xy[1][2] = sPitch; xy[2][2] = cPitch*cYaw;  xy[3][2] = 0.0f;
        xy[0][3] = 0.0f;         xy[1][3] = 0.0f;   xy[2][3] = 0.0f;         xy[3][3] = 1.0f;
        //Re-center the model view
        sgPostMultMat4(modelView,xy);
        //copy float matrices to double
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 4; j++) {
                int idx = (i * 4) + j;
                mm[idx] = (double)modelView[i][j];
                pm[idx] = (double)projMat[i][j];
            }
        }

        //Calculate the 2D points via gluProject
        int result = GL_TRUE;
        for (int i = 0; i < 6; i++) {
            result = gluProject(points3d[i][0], points3d[i][1], points3d[i][2], mm,
                    pm, view, &points2d[i][0], &points2d[i][1], &points2d[i][2]);
        }
        //set the line width based on our distance from the runway
        setLineWidth();
        //Draw the runway lines on the HUD
        glEnable(GL_LINE_STIPPLE);
        glLineStipple(1, stippleOut);
        anyLines =
                drawLine(points3d[0], points3d[1], points2d[0], points2d[1]) | //draw top
                drawLine(points3d[2], points3d[1], points2d[2], points2d[1]) | //draw right
                drawLine(points3d[2], points3d[3], points2d[2], points2d[3]) | //draw bottom
                drawLine(points3d[3], points3d[0], points2d[3], points2d[0]);  //draw left

        glLineStipple(1, stippleCen);
        anyLines |= drawLine(points3d[5], points3d[4], points2d[5], points2d[4]); //draw center

        //Check to see if arrow needs drawn
        if ((!anyLines && drawIA) || drawIAAlways) {
            drawArrow(); //draw indication arrow
        }

        //Restore the current view and any offsets
        if (curr_view_id != 0) {
            globals->get_viewmgr()->set_view(curr_view_id);
            globals->get_viewmgr()->copyToCurrent();
            curr_view->setHeadingOffset_deg(ho);
            curr_view->setPitchOffset_deg(po);
            curr_view->setGoalHeadingOffset_deg(gho);
            curr_view->setGoalPitchOffset_deg(gpo);
        }
        //Set the camera back to the current view
        ssgSetCamera((sgVec4 *)curr_view);
        glPopAttrib();
    }//if not broken
}


bool runway_instr::get_active_runway(FGRunway& runway)
{
    FGEnvironment stationweather =
            ((FGEnvironmentMgr *)globals->get_subsystem("environment"))->getEnvironment();
    double hdg = stationweather.get_wind_from_heading_deg();
    return globals->get_runways()->search(fgGetString("/sim/presets/airport-id"), int(hdg), &runway);
}


void runway_instr::get_rwy_points(sgdVec3 *points3d)
{
    double alt = current_aircraft.fdm_state->get_Runway_altitude() * SG_FEET_TO_METER;
    double length = (runway._length / 2.0) * SG_FEET_TO_METER;
    double width = (runway._width / 2.0) * SG_FEET_TO_METER;
    double frontLat, frontLon, backLat, backLon,az, tempLat, tempLon;

    geo_direct_wgs_84(alt, runway._lat, runway._lon, runway._heading, length, &backLat, &backLon, &az);
    sgGeodToCart(backLat * SG_DEGREES_TO_RADIANS, backLon * SG_DEGREES_TO_RADIANS, alt, points3d[4]);

    geo_direct_wgs_84(alt, runway._lat, runway._lon, runway._heading + 180, length, &frontLat, &frontLon, &az);
    sgGeodToCart(frontLat * SG_DEGREES_TO_RADIANS, frontLon * SG_DEGREES_TO_RADIANS, alt, points3d[5]);

    geo_direct_wgs_84(alt, backLat, backLon, runway._heading + 90, width, &tempLat, &tempLon, &az);
    sgGeodToCart(tempLat * SG_DEGREES_TO_RADIANS, tempLon * SG_DEGREES_TO_RADIANS, alt, points3d[0]);

    geo_direct_wgs_84(alt, backLat, backLon, runway._heading - 90, width, &tempLat, &tempLon, &az);
    sgGeodToCart(tempLat * SG_DEGREES_TO_RADIANS, tempLon * SG_DEGREES_TO_RADIANS, alt, points3d[1]);

    geo_direct_wgs_84(alt, frontLat, frontLon, runway._heading - 90, width, &tempLat, &tempLon, &az);
    sgGeodToCart(tempLat * SG_DEGREES_TO_RADIANS, tempLon * SG_DEGREES_TO_RADIANS, alt, points3d[2]);

    geo_direct_wgs_84(alt, frontLat, frontLon, runway._heading + 90, width, &tempLat, &tempLon, &az);
    sgGeodToCart(tempLat * SG_DEGREES_TO_RADIANS, tempLon * SG_DEGREES_TO_RADIANS, alt, points3d[3]);

    //Get the current tile center
    SGVec3d tileCenter = globals->get_scenery()->get_center();
    for (int i = 0; i < 6; i++) {
        points3d[i][0] -= tileCenter.x();
        points3d[i][1] -= tileCenter.y();
        points3d[i][2] -= tileCenter.z();
    }
}


bool runway_instr::drawLine(const sgdVec3& a1, const sgdVec3& a2, const sgdVec3& point1, const sgdVec3& point2)
{
    sgdVec3 p1, p2;
    sgdCopyVec3(p1, point1);
    sgdCopyVec3(p2, point2);
    bool p1Inside = (p1[0] >= location.left && p1[0] <= location.right
            && p1[1] >= location.bottom && p1[1] <= location.top);
    bool p1Insight = (p1[2] >= 0.0 && p1[2] < 1.0);
    bool p1Valid = p1Insight && p1Inside;
    bool p2Inside = (p2[0] >= location.left && p2[0] <= location.right
            && p2[1] >= location.bottom && p2[1] <= location.top);
    bool p2Insight = (p2[2] >= 0.0 && p2[2] < 1.0);
    bool p2Valid = p2Insight && p2Inside;

    if (p1Valid && p2Valid) { //Both project points are valid, draw the line
        glBegin(GL_LINES);
        glVertex2d(p1[0],p1[1]);
        glVertex2d(p2[0],p2[1]);
        glEnd();

    } else if (p1Valid) { //p1 is valid and p2 is not, calculate a new valid point
        sgdVec3 vec = {a2[0] - a1[0], a2[1] - a1[1], a2[2] - a1[2]};
        //create the unit vector
        sgdScaleVec3(vec, 1.0 / sgdLengthVec3(vec));
        sgdVec3 newPt;
        sgdCopyVec3(newPt, a1);
        sgdAddVec3(newPt, vec);
        if (gluProject(newPt[0], newPt[1], newPt[2], mm, pm, view, &p2[0], &p2[1], &p2[2])
                && (p2[2] > 0 && p2[2] < 1.0)) {
            boundPoint(p1, p2);
            glBegin(GL_LINES);
            glVertex2d(p1[0], p1[1]);
            glVertex2d(p2[0], p2[1]);
            glEnd();
        }

    } else if (p2Valid) { //p2 is valid and p1 is not, calculate a new valid point
        sgdVec3 vec = {a1[0] - a2[0], a1[1] - a2[1], a1[2] - a2[2]};
        //create the unit vector
        sgdScaleVec3(vec, 1.0 / sgdLengthVec3(vec));
        sgdVec3 newPt;
        sgdCopyVec3(newPt, a2);
        sgdAddVec3(newPt, vec);
        if (gluProject(newPt[0], newPt[1], newPt[2], mm, pm, view, &p1[0], &p1[1], &p1[2])
                && (p1[2] > 0 && p1[2] < 1.0)) {
            boundPoint(p2, p1);
            glBegin(GL_LINES);
            glVertex2d(p2[0], p2[1]);
            glVertex2d(p1[0], p1[1]);
            glEnd();
        }

    } else if (p1Insight && p2Insight) { //both points are insight, but not inside
        bool v = boundOutsidePoints(p1, p2);
        if (v) {
            glBegin(GL_LINES);
                glVertex2d(p1[0], p1[1]);
                glVertex2d(p2[0], p2[1]);
            glEnd();
        }
        return v;
    }
    //else both points are not insight, don't draw anything
    return (p1Valid && p2Valid);
}


void runway_instr::boundPoint(const sgdVec3& v, sgdVec3& m)
{
    double y = v[1];
    if (m[1] < v[1])
        y = location.bottom;
    else if (m[1] > v[1])
        y = location.top;

    if (m[0] == v[0]) {
        m[1] = y;
        return;  //prevent divide by zero
    }

    double slope = (m[1] - v[1]) / (m[0] - v[0]);
    m[0] = (y - v[1]) / slope + v[0];
    m[1] = y;

    if (m[0] < location.left) {
        m[0] = location.left;
        m[1] = slope * (location.left - v[0]) + v[1];

    } else if (m[0] > location.right) {
        m[0] = location.right;
        m[1] = slope * (location.right - v[0]) + v[1];
    }
}


bool runway_instr::boundOutsidePoints(sgdVec3& v, sgdVec3& m)
{
    bool pointsInvalid = (v[1] > location.top && m[1] > location.top) ||
                         (v[1] < location.bottom && m[1] < location.bottom) ||
                         (v[0] > location.right && m[0] > location.right) ||
                         (v[0] < location.left && m[0] < location.left);
    if (pointsInvalid)
        return false;

    if (m[0] == v[0]) {//x's are equal, vertical line
        if (m[1] > v[1]) {
            m[1] = location.top;
            v[1] = location.bottom;
        } else {
            v[1] = location.top;
            m[1] = location.bottom;
        }
        return true;
    }

    if (m[1] == v[1]) { //y's are equal, horizontal line
        if (m[0] > v[0]) {
            m[0] = location.right;
            v[0] = location.left;
        } else {
            v[0] = location.right;
            m[0] = location.left;
        }
        return true;
    }

    double slope = (m[1] - v[1]) / (m[0] - v[0]);
    double b = v[1] - (slope * v[0]);
    double y1 = slope * location.left + b;
    double y2 = slope * location.right + b;
    double x1 = (location.bottom - b) / slope;
    double x2 = (location.top - b) / slope;
    int counter = 0;

    if  (y1 >= location.bottom && y1 <= location.top) {
        v[0] = location.left;
        v[1] = y1;
        counter++;
    }

    if (y2 >= location.bottom && y2 <= location.top) {
        if (counter > 0) {
            m[0] = location.right;
            m[1] = y2;
        } else {
            v[0] = location.right;
            v[1] = y2;
        }
        counter++;
    }

    if (x1 >= location.left && x1 <= location.right) {
        if (counter > 0) {
            m[0] = x1;
            m[1] = location.bottom;
        } else {
            v[0] = x1;
            v[1] = location.bottom;
        }
        counter++;
    }

    if (x2 >= location.left && x2 <= location.right) {
        m[0] = x1;
        m[1] = location.bottom;
        counter++;
    }
    return (counter == 2);
}

void runway_instr::drawArrow()
{
    Point3D ac(0.0), rwy(0.0);
    ac.setlat(current_aircraft.fdm_state->get_Latitude_deg());
    ac.setlon(current_aircraft.fdm_state->get_Longitude_deg());
    rwy.setlat(runway._lat);
    rwy.setlon(runway._lon);
    float theta = GetHeadingFromTo(ac, rwy);
    theta -= fgGetDouble("/orientation/heading-deg");
    theta = -theta;
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glTranslated((location.right + location.left) / 2.0,(location.top + location.bottom) / 2.0, 0.0);
    glRotated(theta, 0.0, 0.0, 1.0);
    glTranslated(0.0, arrowRad, 0.0);
    glScaled(arrowScale, arrowScale, 0.0);

    glBegin(GL_TRIANGLES);
    glVertex2d(-5.0, 12.5);
    glVertex2d(0.0, 25.0);
    glVertex2d(5.0, 12.5);
    glEnd();

    glBegin(GL_QUADS);
    glVertex2d(-2.5, 0.0);
    glVertex2d(-2.5, 12.5);
    glVertex2d(2.5, 12.5);
    glVertex2d(2.5, 0.0);
    glEnd();
    glPopMatrix();
}

void runway_instr::setLineWidth()
{
    //Calculate the distance from the runway, A
    double course, distance;
    calc_gc_course_dist(Point3D(runway._lon * SGD_DEGREES_TO_RADIANS,
            runway._lat * SGD_DEGREES_TO_RADIANS, 0.0),
            Point3D(current_aircraft.fdm_state->get_Longitude(),
            current_aircraft.fdm_state->get_Latitude(), 0.0 ),
            &course, &distance);
    distance *= SG_METER_TO_NM;
    //Get altitude above runway, B
    double alt_nm = get_agl();
    static const SGPropertyNode *startup_units_node = fgGetNode("/sim/startup/units");

    if (!strcmp(startup_units_node->getStringValue(), "feet"))
        alt_nm *= SG_FEET_TO_METER*SG_METER_TO_NM;
    else
        alt_nm *= SG_METER_TO_NM;

    //Calculate distance away from runway, C = v(AČ+BČ)
    distance = sqrt(alt_nm * alt_nm + distance*distance);
    if (distance < scaleDist)
        glLineWidth(1.0 + ((lnScale - 1) * ((scaleDist - distance) / scaleDist)));
    else
        glLineWidth(1.0);

}

void runway_instr::setArrowRotationRadius(double radius) { arrowRad = radius; }
void runway_instr::setArrowScale(double scale) { arrowScale = scale; }
void runway_instr::setDrawArrow(bool draw) {drawIA = draw;}
void runway_instr::setDrawArrowAlways(bool draw) {drawIAAlways = draw;}
void runway_instr::setLineScale(double scale) {lnScale = scale;}
void runway_instr::setScaleDist(double dist_m) {scaleDist = dist_m;}
void runway_instr::setStippleOutline(unsigned short stipple) {stippleOut = stipple;}
void runway_instr::setStippleCenterline(unsigned short stipple){stippleCen = stipple;}