#include "externals.hh"
#include "camera.hh"
#include "utilities.hh"


/*= T_Camera =================================================================*/

void T_Camera::handleDND(
		__rd__	ImVec2 const& move ,
		__rd__	const bool hasCtrl ,
		__rd__	const bool hasShift ,
		__rd__	const bool lmb		// Left mouse button
	)
{
	if ( move.x == 0 || move.y == 0 ) {
		return;
	}

	const float fdx( move.x * .1f * ( hasCtrl ? 1.f : .1f ) );
	const float fdy( move.y * .1f * ( hasCtrl ? 1.f : .1f ) );

	if ( lmb && hasShift ) {
		// Left mouse button, shift - move camera
		const auto side( glm::normalize( glm::cross( up , dir ) ) );
		lookAt += .1f * ( side * fdx + up * fdy );
	} else if ( lmb ) {
		// Left mouse button, no shift - change yaw/pitch
		updateAngle( angles.y , fdx );
		updateAngle( angles.x , fdy );
	} else {
		// Right mouse button - change roll
		updateAngle( angles.z , fdx );
	}
	update( );
}

void T_Camera::handleWheel(
		__rd__	const float wheel ,
		__rd__	const bool hasCtrl ,
		__rd__	const bool hasShift
	)
{
	const float delta( wheel * ( hasCtrl ? 1.f : .1f) );
	if ( hasShift ) {
		fov = std::max( 1.f , std::min( 179.f , fov + delta ) );
	} else {
		distance = std::max( .01f , distance - delta );
	}
	update( );
}

/*----------------------------------------------------------------------------*/

void T_Camera::makeUI( )
{
	if ( !ImGui::CollapsingHeader( "Camera" ) ) {
		return;
	}

	const bool changed[] = {
		ImGui::DragFloat3( "Look at" , &lookAt.x ) ,
		ImGui::DragFloat( "Distance" , &distance , .1f ,
				.1f , 1e8 , "%.1f" ) ,
		ImGui::DragFloat3( "Angles" , &angles.x , .01f , -180 , 180 ) ,
		ImGui::DragFloat( "FoV" , &fov , .01f , .01f , 179.9f )
	};

	for ( unsigned i = 0 ; i < sizeof( changed ) / sizeof( bool ) ; i ++ ) {
		if ( changed[ i ] ) {
			update( );
			break;
		}
	}
}

/*----------------------------------------------------------------------------*/

void T_Camera::update( )
{
	anglesToMatrix( &angles.x , &rotMat[ 0 ].x );
	dir = glm::vec3( 0 , 0 , -distance ) * rotMat;
	up = glm::vec3( 0 , 1 , 0 ) * rotMat;
	pos = lookAt - dir;
	np = 2 * tan( M_PI * ( 180. - fov ) / 360. );
}