#![ cfg( feature = "test-support" ) ]

use ltk::test_support::{ value_from_x_in_rect, thumb_design_px };
use ltk::Rect;

fn rect( x: f32, y: f32, w: f32, h: f32 ) -> Rect
{
	Rect { x, y, width: w, height: h }
}

/// The thumb size the pure math is exercised with — the design constant, so
/// the pad matches what the renderer draws with an unscaled thumb.
fn thumb() -> f32 { thumb_design_px() }

#[ test ]
fn left_edge_clamps_to_zero()
{
	let r = rect( 0.0, 0.0, 200.0, 36.0 );
	assert_eq!( value_from_x_in_rect( r, 0.0, thumb() ), 0.0 );
	assert_eq!( value_from_x_in_rect( r, -50.0, thumb() ), 0.0 );
}

#[ test ]
fn right_edge_clamps_to_one()
{
	let r = rect( 0.0, 0.0, 200.0, 36.0 );
	assert_eq!( value_from_x_in_rect( r, 200.0, thumb() ), 1.0 );
	assert_eq!( value_from_x_in_rect( r, 999.0, thumb() ), 1.0 );
}

#[ test ]
fn center_returns_half()
{
	// The thumb adds padding on both sides, so the geometric center of the
	// rect produces ~0.5 (within the THUMB_SIZE/2 tolerance).
	let r = rect( 0.0, 0.0, 200.0, 36.0 );
	let v = value_from_x_in_rect( r, 100.0, thumb() );
	assert!( ( v - 0.5 ).abs() < 0.1, "expected ~0.5 got {}", v );
}

#[ test ]
fn rect_offset_translates_correctly()
{
	let r = rect( 500.0, 0.0, 200.0, 36.0 );
	assert_eq!( value_from_x_in_rect( r, 500.0, thumb() ), 0.0 );
	assert_eq!( value_from_x_in_rect( r, 700.0, thumb() ), 1.0 );
	let v = value_from_x_in_rect( r, 600.0, thumb() );
	assert!( ( v - 0.5 ).abs() < 0.1, "expected ~0.5 got {}", v );
}

#[ test ]
fn output_is_always_in_unit_range()
{
	let r = rect( 10.0, 10.0, 300.0, 36.0 );
	for x in -100i32 ..= 500
	{
		let v = value_from_x_in_rect( r, x as f32, thumb() );
		assert!( ( 0.0..= 1.0 ).contains( &v ), "v={} out of range at x={}", v, x );
	}
}

#[ test ]
fn very_narrow_rect_does_not_divide_by_zero()
{
	// Width < THUMB_SIZE — track_w is clamped to 1.0 internally so the
	// formula stays defined.
	let r = rect( 0.0, 0.0, 4.0, 36.0 );
	let v = value_from_x_in_rect( r, 2.0, thumb() );
	assert!( v.is_finite() );
	assert!( ( 0.0..= 1.0 ).contains( &v ) );
}