#include "util.h"
#include <SDL3/SDL.h>

// Funcions de càlcul

// Returns 1 if the lines intersect, otherwise 0. In addition, if the lines 
// intersect the intersection point may be stored in the floats i_x and i_y.
const bool get_line_intersection(vec2 p0, vec2 p1, vec2 p2, vec2 p3, vec2 *i)
{
    vec2 s1, s2;
    s1.x = p1.x - p0.x;     s1.y = p1.y - p0.y;
    s2.x = p3.x - p2.x;     s2.y = p3.y - p2.y;

    float s, t;
    s = (-s1.y * (p0.x - p2.x) + s1.x * (p0.y - p2.y)) / (-s2.x * s1.y + s1.x * s2.y);
    t = ( s2.x * (p0.y - p2.y) - s2.y * (p0.x - p2.x)) / (-s2.x * s1.y + s1.x * s2.y);

    if (s >= 0 && s <= 1 && t >= 0 && t <= 1)
    {
        // Collision detected
        if (i != NULL)
        {
            i->x = p0.x + (t * s1.x);
            i->y = p0.y + (t * s1.y);
            
        }
        return true;
    }

    return false; // No collision
}

const float distance(vec2 p1, vec2 p2)
{
    const float xx = p2.x-p1.x;
    const float yy = p2.y-p1.y;
    return SDL_sqrtf(xx*xx+yy*yy);
}

const void normalize(vec2 *v)
{
    const float length = SDL_sqrtf(v->x*v->x + v->y*v->y);
    if (length > 0.0f) {
        v->x /= length;
        v->y /= length;
    }
}

const float dot(vec2 v1, vec2 v2)
{
    return v1.x*v2.x + v1.y*v2.y;
}

float is_enemy_in_fov(double Ax, double Ay, double orientation_deg, double Bx, double By) {
    // Convert orientation angle to radians
    double orientation_rad = orientation_deg * DEG_TO_RAD;

    // Compute view direction vector from angle
    double view_dx = SDL_cosf(orientation_rad);
    double view_dy = SDL_sinf(orientation_rad);

    // Vector from A to B
    double to_enemy_dx = Bx - Ax;
    double to_enemy_dy = By - Ay;

    // Normalize both vectors
    double len = SDL_sqrtf(to_enemy_dx * to_enemy_dx + to_enemy_dy * to_enemy_dy);
    if (len == 0) return 0.0; // Same position

    to_enemy_dx /= len;
    to_enemy_dy /= len;

    // Compute signed angle using atan2 of perp-dot and dot
    double dot = view_dx * to_enemy_dx + view_dy * to_enemy_dy;
    double cross = view_dx * to_enemy_dy - view_dy * to_enemy_dx;

    float angle_rad = SDL_atan2f(cross, dot);
    return angle_rad * RAD_TO_DEG; // Signed angle in degrees
}