package sectr

import rl "vendor:raylib"

// The points to pixels and pixels to points are our only reference to accurately converting
// an object from world space to screen-space.
// This prototype engine will have all its spacial unit base for distances in centimetres.

Inches_To_Centimetre  :: cast(f32) 2.54
Points_Per_Centimetre := cast(f32) 28.3465
Centimetres_Per_Point :: cast(f32) 1.0 / 28.3465 // Precalculated reciprocal for multiplication
DPT_DPC               :: cast(f32) 72.0 * Inches_To_Centimetre

when ODIN_OS == OS_Type.Windows {
	os_default_dpc :: 96 * Inches_To_Centimetre
	// 1 inch = 2.54 cm, 96 inch * 2.54 = 243.84 DPC
}

cm_to_pixels :: proc( cm : f32 ) -> f32 {
	screen_dpc := get_state().app_window.dpc
	return cm * screen_dpc
}

vec2_cm_to_pixels :: proc( v : Vec2 ) -> Vec2 {
	screen_dpc := get_state().app_window.dpc
	return v * screen_dpc
}

points_to_pixels :: proc( points : f32 ) -> f32 {
	screen_dpc := get_state().app_window.dpc
	cm_per_pixel := 1.0 / screen_dpc
	return points * DPT_DPC * cm_per_pixel
}

pixels_to_points :: proc( pixels : f32 ) -> f32 {
	screen_dpc := get_state().app_window.dpc
	cm_per_pixel := 1.0 / screen_dpc
	return pixels * cm_per_pixel * Points_Per_Centimetre
}

vec2_points_to_pixels :: proc ( vpoints : Vec2 ) -> Vec2 {
	screen_dpc := get_state().app_window.dpc
	cm_per_pixel := 1.0 / screen_dpc
	return vpoints * DPT_DPC * cm_per_pixel
}

Camera :: rl.Camera2D

AreaSize :: distinct Vec2

Bounds2 :: struct {
	top_left, bottom_right : Vec2
}

BoundsCorners2 :: struct {
	top_left, top_right, bottom_left, bottom_right : Vec2
}

Extents2  :: distinct Vec2
Extents2i :: distinct Vec2i

bounds2_radius :: proc( bounds : Bounds2 ) -> f32 {
	return max( bounds.bottom_right.x, bounds.top_left.y )
}

extent_from_size :: proc ( size : AreaSize ) -> Extents2 {
	return transmute(Extents2) size * 2.0
}

screen_size :: proc "contextless" () -> AreaSize {
	extent := get_state().app_window.extent
	return transmute(AreaSize) (extent * 2.0)
}

screen_get_corners :: proc() -> BoundsCorners2 {
	state := get_state(); using state
	screen_extent := state.app_window.extent
	top_left     := Vec2 { -screen_extent.x,  screen_extent.y }
	top_right    := Vec2 {  screen_extent.x,  screen_extent.y }
	bottom_left  := Vec2 { -screen_extent.x, -screen_extent.y }
	bottom_right := Vec2 {  screen_extent.x, -screen_extent.y }
	return { top_left, top_right, bottom_left, bottom_right }
}

view_get_bounds :: proc() -> Bounds2 {
	state         := get_state(); using state
	cam           := & project.workspace.cam
	screen_extent := state.app_window.extent
	top_left     := cam.target + Vec2 { -screen_extent.x,  screen_extent.y }
	bottom_right := cam.target + Vec2 {  screen_extent.x, -screen_extent.y }
	return { top_left, bottom_right }
}

view_get_corners :: proc() -> BoundsCorners2 {
	state          := get_state(); using state
	cam            := & project.workspace.cam
	cam_zoom_ratio := 1.0 / cam.zoom
	screen_extent  := state.app_window.extent * cam_zoom_ratio
	top_left     := cam.target + Vec2 { -screen_extent.x,  screen_extent.y }
	top_right    := cam.target + Vec2 {  screen_extent.x,  screen_extent.y }
	bottom_left  := cam.target + Vec2 { -screen_extent.x, -screen_extent.y }
	bottom_right := cam.target + Vec2 {  screen_extent.x, -screen_extent.y }
	return { top_left, top_right, bottom_left, bottom_right }
}

screen_to_render :: proc( pos : Vec2 ) -> Vec2 {
	screen_extent := transmute(Vec2) get_state().project.workspace.cam.offset
	return pos + { screen_extent.x, -screen_extent.y }
}

world_screen_extent :: proc () -> Extents2 {
	state          := get_state(); using state
	cam_zoom_ratio := 1.0 / project.workspace.cam.zoom
	return app_window.extent * cam_zoom_ratio
}

world_to_screen_pos :: proc( position : Vec2 ) -> Vec2 {
	return { position.x, position.y * -1 }
}

world_to_screen_no_zoom :: proc( position : Vec2 ) -> Vec2 {
	state          := get_state(); using state
	cam_zoom_ratio := 1.0 / state.project.workspace.cam.zoom
	return { position.x, position.y * -1 } * cam_zoom_ratio
}