use cgmath::{Matrix4, Point3, Vector3, Deg, perspective, InnerSpace, Rotation, Quaternion, Rotation3, Rad};

#[derive(Debug)]
pub struct Camera {
    pub eye: Point3<f32>,
    pub target: Point3<f32>,
    pub up: Vector3<f32>,
    pub fov_y: Deg<f32>,
    pub aspect: f32,
    pub znear: f32,
    pub zfar: f32,
}

impl Camera {
    pub fn new(aspect: f32) -> Self {
        Self {
            eye: Point3::new(0.0, 0.0, 5.0),
            target: Point3::new(0.0, 0.0, 0.0),
            up: Vector3::unit_y(),
            fov_y: Deg(45.0),
            aspect,
            znear: 0.1,
            zfar: 100.0,
        }
    }

    pub fn build_view_projection_matrix(&self) -> Matrix4<f32> {
        let view = Matrix4::look_at_rh(self.eye, self.target, self.up);
        let proj = perspective(self.fov_y, self.aspect, self.znear, self.zfar);
        proj * view
    }
    
    pub fn build_view_matrix(&self) -> Matrix4<f32> {
        Matrix4::look_at_rh(self.eye, self.target, self.up)
    }

    pub fn rotate_yaw_pitch(&mut self, yaw: f32, pitch: f32) {
        let offset = self.eye - self.target;
        let distance = offset.magnitude();

        let yaw_q = Quaternion::from_axis_angle(Vector3::unit_y(), Rad(yaw.to_radians()));
        let right = offset.cross(self.up).normalize();
        let pitch_q = Quaternion::from_axis_angle(right, Rad(pitch.to_radians()));

        let rotation = yaw_q * pitch_q;
        let new_offset = rotation.rotate_vector(offset);

        self.eye = self.target + new_offset;
        self.up = rotation.rotate_vector(self.up);
    }
    
    pub fn translate(&mut self, translation: Vector3<f32>) {
        let dir = (self.target - self.eye).normalize();
        let horizontal = Vector3::unit_y().cross(dir).normalize();
        let vertical = horizontal.cross(dir).normalize();

        self.eye += horizontal * translation.x + vertical * translation.y;
        self.target += horizontal * translation.x + vertical * translation.y;
    }

    pub fn zoom(&mut self, amount: f32) {
        let dir = (self.target - self.eye).normalize();
        self.eye += dir * amount;
    }

    pub fn set_aspect(&mut self, aspect: f32) {
        self.aspect = aspect;
    }
}