#include <GL/glut.h>
#include <stdlib.h>
#include <time.h>
#include <stdio.h>

int WINDOW_WIDTH = 800;
int WINDOW_HEIGHT = 600;
int numVertices = 5; // Initial number of vertices for the polygon
int pointX = 400;    // Initial x-coordinate of the point
int pointY = 300;    // Initial y-coordinate of the point
typedef struct {
    int x, y;
} Point;
Point *polygonVertices = NULL; // Dynamic array for storing polygon vertices

// Function to generate initial polygon vertices
void initPolygonVertices() {
    polygonVertices = realloc(polygonVertices, numVertices * sizeof(Point));
    for (int i = 0; i < numVertices; ++i) {
        polygonVertices[i].x = rand() % WINDOW_WIDTH;
        polygonVertices[i].y = rand() % WINDOW_HEIGHT;
    }
}

// Function to draw a polygon
void drawPolygon() {
    glColor3f(0.0, 0.5, 0.8); // Set color for the polygon (light blue)
    glBegin(GL_POLYGON);
    for (int i = 0; i < numVertices; ++i) {
        glVertex2f(polygonVertices[i].x, polygonVertices[i].y);
    }
    glEnd();
}

// Function to draw a point
void drawPoint() {
    glColor3f(1.0, 0.0, 0.0); // Set color for the point (red)
    glPointSize(5); // Set point size for better visibility
    glBegin(GL_POINTS);
    glVertex2f(pointX, pointY);
    glEnd();
}

// Check if point is inside polygon using ray-casting algorithm
int isPointInsidePolygon(int x, int y) {
    int inside = 0;
    int n = numVertices;
    for (int i = 0, j = n - 1; i < n; j = i++) {
        int intersect = ((polygonVertices[i].y > y) != (polygonVertices[j].y > y)) &&
                        (x < (polygonVertices[j].x - polygonVertices[i].x) * (y - polygonVertices[i].y) / (polygonVertices[j].y - polygonVertices[i].y) + polygonVertices[i].x);
        if (intersect) {
            inside = !inside;
        }
    }
    return inside;
}

// Function to handle window drawing
void display() {
    glClear(GL_COLOR_BUFFER_BIT);

    // Draw the polygon
    drawPolygon();

    // Draw the point
    drawPoint();

    // Check if point is inside polygon and print the result
    if (isPointInsidePolygon(pointX, pointY)) {
        printf("The point is inside the polygon.\n");
    } else {
        printf("The point is outside the polygon.\n");
    }

    glFlush();
}

// Function to handle window resizing
void reshape(int w, int h) {
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0, w, 0, h);
    glMatrixMode(GL_MODELVIEW);
    WINDOW_WIDTH = w;
    WINDOW_HEIGHT = h;
}

// Function to handle keyboard input
void keyboard(unsigned char key, int x, int y) {
    switch (key) {
        case '+':
            numVertices++;
            if (numVertices > 2) {
                initPolygonVertices(); // Regenerate polygon vertices
                glutPostRedisplay(); // Redraw window
            }
            break;
        case '-':
            if (numVertices > 3) {
                numVertices--;
                initPolygonVertices(); // Regenerate polygon vertices
                glutPostRedisplay(); // Redraw window
            }
            break;
        default:
            break;
    }
}

// Function to handle mouse input (move the point)
void mouse(int button, int state, int x, int y) {
    if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
        pointX = x;
        pointY = WINDOW_HEIGHT - y; // Invert y-coordinate to match OpenGL convention
        glutPostRedisplay(); // Redraw window
    }
}

int main(int argc, char** argv) {
    srand(time(NULL)); // Seed random number generator
    initPolygonVertices(); // Initialize polygon vertices

    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(WINDOW_WIDTH, WINDOW_HEIGHT);
    glutCreateWindow("Polygon and Point in C");

    glutDisplayFunc(display);
    glutReshapeFunc(reshape);

    glutKeyboardFunc(keyboard);
    glutMouseFunc(mouse);

    glClearColor(1.0, 1.0, 1.0, 1.0); // Set background color to white

    glutMainLoop();

    return 0;
}