use anyhow::anyhow;
use cocoa::appkit::CGFloat;
use collections::HashMap;
use core_foundation::{
	array::{CFArray, CFArrayRef},
	attributed_string::CFMutableAttributedString,
	base::{CFRange, CFType, TCFType},
	number::CFNumber,
	string::CFString,
};
use core_graphics::{
	base::{CGGlyph, kCGImageAlphaPremultipliedLast},
	color_space::CGColorSpace,
	context::{CGContext, CGTextDrawingMode},
	display::CGPoint,
};
use core_text::{
	font::CTFont,
	font_collection::CTFontCollectionRef,
	font_descriptor::{
		CTFontDescriptor, kCTFontSlantTrait, kCTFontSymbolicTrait, kCTFontWeightTrait,
		kCTFontWidthTrait,
	},
	line::CTLine,
	string_attributes::{kCTFontAttributeName, kCTKernAttributeName},
};
use font_kit::{
	font::Font as FontKitFont,
	handle::Handle,
	hinting::HintingOptions,
	metrics::Metrics,
	properties::{Style as FontkitStyle, Weight as FontkitWeight},
	source::SystemSource,
	sources::mem::MemSource,
};
use gpui::{
	Bounds, DevicePixels, Font, FontFallbacks, FontFeatures, FontId, FontMetrics, FontRun,
	FontStyle, FontWeight, GlyphId, Hsla, LineLayout, Pixels, PlatformTextSystem,
	RenderGlyphParams, Result, Rgba, SUBPIXEL_VARIANTS_X, ShapedGlyph, ShapedRun, SharedString,
	Size, TextRenderingMode, point, px, size, swap_rgba_pa_to_bgra,
};
use parking_lot::{RwLock, RwLockUpgradableReadGuard};
use pathfinder_geometry::{
	rect::{RectF, RectI},
	transform2d::Transform2F,
	vector::Vector2F,
};
use smallvec::SmallVec;
use std::{borrow::Cow, char, convert::TryFrom, sync::Arc, sync::OnceLock};

use crate::open_type::apply_features_and_fallbacks;

#[allow(non_upper_case_globals)]
const kCGImageAlphaOnly: u32 = 7;

/// macOS text system using CoreText for font shaping.
pub struct MacTextSystem(RwLock<MacTextSystemState>);

#[derive(Clone, PartialEq, Eq, Hash)]
struct FontKey {
	font_family: SharedString,
	font_features: FontFeatures,
	font_fallbacks: Option<FontFallbacks>,
}

struct MacTextSystemState {
	memory_source: MemSource,
	system_source: SystemSource,
	fonts: Vec<FontKitFont>,
	font_selections: HashMap<Font, FontId>,
	font_ids_by_postscript_name: HashMap<String, FontId>,
	font_ids_by_font_key: HashMap<FontKey, SmallVec<[FontId; 4]>>,
	postscript_names_by_font_id: HashMap<FontId, String>,
}

impl MacTextSystem {
	/// Create a new MacTextSystem.
	pub fn new() -> Self {
		Self(RwLock::new(MacTextSystemState {
			memory_source: MemSource::empty(),
			system_source: SystemSource::new(),
			fonts: Vec::new(),
			font_selections: HashMap::default(),
			font_ids_by_postscript_name: HashMap::default(),
			font_ids_by_font_key: HashMap::default(),
			postscript_names_by_font_id: HashMap::default(),
		}))
	}
}

impl Default for MacTextSystem {
	fn default() -> Self {
		Self::new()
	}
}

impl PlatformTextSystem for MacTextSystem {
	fn add_fonts(&self, fonts: Vec<Cow<'static, [u8]>>) -> Result<()> {
		self.0.write().add_fonts(fonts)
	}

	fn all_font_names(&self) -> Vec<String> {
		let mut names = Vec::new();
		let collection = core_text::font_collection::create_for_all_families();
		// NOTE: We intentionally avoid using `collection.get_descriptors()` here because
		// it has a memory leak bug in core-text v21.0.0. The upstream code uses
		// `wrap_under_get_rule` but `CTFontCollectionCreateMatchingFontDescriptors`
		// follows the Create Rule (caller owns the result), so it should use
		// `wrap_under_create_rule`. We call the function directly with correct memory management.
		unsafe extern "C" {
			fn CTFontCollectionCreateMatchingFontDescriptors(
				collection: CTFontCollectionRef,
			) -> CFArrayRef;
		}
		let descriptors: Option<CFArray<CTFontDescriptor>> = unsafe {
			let array_ref =
				CTFontCollectionCreateMatchingFontDescriptors(collection.as_concrete_TypeRef());
			if array_ref.is_null() {
				None
			} else {
				Some(CFArray::wrap_under_create_rule(array_ref))
			}
		};
		let Some(descriptors) = descriptors else {
			return names;
		};
		for descriptor in descriptors.into_iter() {
			names.extend(lenient_font_attributes::family_name(&descriptor));
		}
		if let Ok(fonts_in_memory) = self.0.read().memory_source.all_families() {
			names.extend(fonts_in_memory);
		}
		names
	}

	fn font_id(&self, font: &Font) -> Result<FontId> {
		let lock = self.0.upgradable_read();
		if let Some(font_id) = lock.font_selections.get(font) {
			Ok(*font_id)
		} else {
			let mut lock = RwLockUpgradableReadGuard::upgrade(lock);
			let font_key = FontKey {
				font_family: font.family.clone(),
				font_features: font.features.clone(),
				font_fallbacks: font.fallbacks.clone(),
			};
			let candidates = if let Some(font_ids) = lock.font_ids_by_font_key.get(&font_key) {
				font_ids.as_slice()
			} else {
				let font_ids =
					lock.load_family(&font.family, &font.features, font.fallbacks.as_ref())?;
				lock.font_ids_by_font_key.insert(font_key.clone(), font_ids);
				lock.font_ids_by_font_key[&font_key].as_ref()
			};

			let candidate_properties = candidates
				.iter()
				.map(|font_id| lock.fonts[font_id.0].properties())
				.collect::<SmallVec<[_; 4]>>();

			let ix = font_kit::matching::find_best_match(
				&candidate_properties,
				&font_kit::properties::Properties {
					style: fontkit_style(font.style),
					weight: fontkit_weight(font.weight),
					stretch: Default::default(),
				},
			)?;

			let font_id = candidates[ix];
			lock.font_selections.insert(font.clone(), font_id);
			Ok(font_id)
		}
	}

	fn font_metrics(&self, font_id: FontId) -> FontMetrics {
		font_kit_metrics_to_metrics(self.0.read().fonts[font_id.0].metrics())
	}

	fn typographic_bounds(&self, font_id: FontId, glyph_id: GlyphId) -> Result<Bounds<f32>> {
		Ok(bounds_from_rect(
			self.0.read().fonts[font_id.0].typographic_bounds(glyph_id.0)?,
		))
	}

	fn advance(&self, font_id: FontId, glyph_id: GlyphId) -> Result<Size<f32>> {
		self.0.read().advance(font_id, glyph_id)
	}

	fn glyph_for_char(&self, font_id: FontId, ch: char) -> Option<GlyphId> {
		self.0.read().glyph_for_char(font_id, ch)
	}

	fn glyph_raster_bounds(&self, params: &RenderGlyphParams) -> Result<Bounds<DevicePixels>> {
		self.0.read().raster_bounds(params)
	}

	fn rasterize_glyph(
		&self,
		glyph_id: &RenderGlyphParams,
		raster_bounds: Bounds<DevicePixels>,
	) -> Result<(Size<DevicePixels>, Vec<u8>)> {
		self.0.read().rasterize_glyph(glyph_id, raster_bounds)
	}

	fn layout_line(&self, text: &str, font_size: Pixels, font_runs: &[FontRun]) -> LineLayout {
		self.0.write().layout_line(text, font_size, font_runs)
	}

	fn recommended_rendering_mode(
		&self,
		_font_id: FontId,
		_font_size: Pixels,
	) -> TextRenderingMode {
		TextRenderingMode::Grayscale
	}

	fn glyph_dilation_for_color(&self, color: Hsla) -> u8 {
		// When font smoothing is enabled, CoreGraphics thickens glyph strokes by an amount that
		// depends on the foreground color's luminance. We replicate the logic used by CoreGraphics
		// to select between the different levels of dilation.
		if !font_smoothing_allowed_by_user() {
			return 0;
		}
		let rgba: Rgba = color.into();
		let luminance = 0.2126 * rgba.r + 0.7152 * rgba.g + 0.0722 * rgba.b;
		let level = ((4.0 * luminance) + 0.5).floor() as i32;
		level.clamp(0, 4) as u8
	}
}

fn font_smoothing_allowed_by_user() -> bool {
	static ALLOWED: OnceLock<bool> = OnceLock::new();
	*ALLOWED.get_or_init(|| {
		use core_foundation_sys::preferences::{
			CFPreferencesCopyAppValue, kCFPreferencesCurrentApplication,
		};

		let key = CFString::new("AppleFontSmoothing");
		let value_ref = unsafe {
			CFPreferencesCopyAppValue(key.as_concrete_TypeRef(), kCFPreferencesCurrentApplication)
		};
		if value_ref.is_null() {
			return true;
		}
		let value = unsafe { CFType::wrap_under_create_rule(value_ref) };
		let Some(number) = value.downcast_into::<CFNumber>() else {
			return true;
		};
		// Only an explicit value of `0` means that font smoothing is disabled.
		number.to_i64() != Some(0)
	})
}

impl MacTextSystemState {
	fn add_fonts(&mut self, fonts: Vec<Cow<'static, [u8]>>) -> Result<()> {
		let fonts = fonts
			.into_iter()
			.map(|bytes| match bytes {
				Cow::Borrowed(embedded_font) => {
					let data_provider = unsafe {
						core_graphics::data_provider::CGDataProvider::from_slice(embedded_font)
					};
					let font = core_graphics::font::CGFont::from_data_provider(data_provider)
						.map_err(|()| anyhow!("Could not load an embedded font."))?;
					let font = font_kit::loaders::core_text::Font::from_core_graphics_font(font);
					Ok(Handle::from_native(&font))
				}
				Cow::Owned(bytes) => Ok(Handle::from_memory(Arc::new(bytes), 0)),
			})
			.collect::<Result<Vec<_>>>()?;
		self.memory_source.add_fonts(fonts.into_iter())?;
		Ok(())
	}

	fn load_family(
		&mut self,
		name: &str,
		features: &FontFeatures,
		fallbacks: Option<&FontFallbacks>,
	) -> Result<SmallVec<[FontId; 4]>> {
		let name = gpui::font_name_with_fallbacks(name, ".AppleSystemUIFont");

		let mut font_ids = SmallVec::new();
		let family = self
			.memory_source
			.select_family_by_name(name)
			.or_else(|_| self.system_source.select_family_by_name(name))?;
		for font in family.fonts() {
			let mut font = font.load()?;

			apply_features_and_fallbacks(&mut font, features, fallbacks)?;
			// This block contains a precautionary fix to guard against loading fonts
			// that might cause panics due to `.unwrap()`s up the chain.
			{
				// We use the 'm' character for text measurements in various spots
				// (e.g., the editor). However, at time of writing some of those usages
				// will panic if the font has no 'm' glyph.
				//
				// Therefore, we check up front that the font has the necessary glyph.
				let has_m_glyph = font.glyph_for_char('m').is_some();

				// HACK: The 'Segoe Fluent Icons' font does not have an 'm' glyph,
				// but we need to be able to load it for rendering Windows icons in
				// the Storybook (on macOS).
				let is_segoe_fluent_icons = font.full_name() == "Segoe Fluent Icons";

				if !has_m_glyph && !is_segoe_fluent_icons {
					// I spent far too long trying to track down why a font missing the 'm'
					// character wasn't loading. This log statement will hopefully save
					// someone else from suffering the same fate.
					log::warn!(
						"font '{}' has no 'm' character and was not loaded",
						font.full_name()
					);
					continue;
				}
			}

			// We've seen a number of panics in production caused by calling font.properties()
			// which unwraps a downcast to CFNumber. This is an attempt to avoid the panic,
			// and to try and identify the incalcitrant font.
			let traits = font.native_font().all_traits();
			if unsafe {
				!(traits
					.get(kCTFontSymbolicTrait)
					.downcast::<CFNumber>()
					.is_some() && traits
					.get(kCTFontWidthTrait)
					.downcast::<CFNumber>()
					.is_some() && traits
					.get(kCTFontWeightTrait)
					.downcast::<CFNumber>()
					.is_some() && traits
					.get(kCTFontSlantTrait)
					.downcast::<CFNumber>()
					.is_some())
			} {
				log::error!(
					"Failed to read traits for font {:?}",
					font.postscript_name().unwrap()
				);
				continue;
			}

			let font_id = FontId(self.fonts.len());
			font_ids.push(font_id);
			let postscript_name = font.postscript_name().unwrap();
			self.font_ids_by_postscript_name
				.insert(postscript_name.clone(), font_id);
			self.postscript_names_by_font_id
				.insert(font_id, postscript_name);
			self.fonts.push(font);
		}
		Ok(font_ids)
	}

	fn advance(&self, font_id: FontId, glyph_id: GlyphId) -> Result<Size<f32>> {
		Ok(size_from_vector2f(
			self.fonts[font_id.0].advance(glyph_id.0)?,
		))
	}

	fn glyph_for_char(&self, font_id: FontId, ch: char) -> Option<GlyphId> {
		self.fonts[font_id.0].glyph_for_char(ch).map(GlyphId)
	}

	fn id_for_native_font(&mut self, requested_font: CTFont) -> FontId {
		let postscript_name = requested_font.postscript_name();
		if let Some(font_id) = self.font_ids_by_postscript_name.get(&postscript_name) {
			*font_id
		} else {
			let font_id = FontId(self.fonts.len());
			self.font_ids_by_postscript_name
				.insert(postscript_name.clone(), font_id);
			self.postscript_names_by_font_id
				.insert(font_id, postscript_name);
			self.fonts
				.push(font_kit::font::Font::from_core_graphics_font(
					requested_font.copy_to_CGFont(),
				));
			font_id
		}
	}

	fn is_emoji(&self, font_id: FontId) -> bool {
		self.postscript_names_by_font_id
			.get(&font_id)
			.is_some_and(|postscript_name| {
				postscript_name == "AppleColorEmoji" || postscript_name == ".AppleColorEmojiUI"
			})
	}

	fn raster_bounds(&self, params: &RenderGlyphParams) -> Result<Bounds<DevicePixels>> {
		let font = &self.fonts[params.font_id.0];
		let scale = Transform2F::from_scale(params.scale_factor);
		let bounds: Bounds<DevicePixels> = bounds_from_rect_i(font.raster_bounds(
			params.glyph_id.0,
			params.font_size.into(),
			scale,
			HintingOptions::None,
			font_kit::canvas::RasterizationOptions::GrayscaleAa,
		)?);

		// Expand the bounds by 1 pixel on each side to give CG room for anti-aliasing.
		Ok(bounds.dilate(DevicePixels(1)))
	}

	fn rasterize_glyph(
		&self,
		params: &RenderGlyphParams,
		glyph_bounds: Bounds<DevicePixels>,
	) -> Result<(Size<DevicePixels>, Vec<u8>)> {
		if glyph_bounds.size.width.0 == 0 || glyph_bounds.size.height.0 == 0 {
			anyhow::bail!("glyph bounds are empty");
		} else {
			// Add an extra pixel when the subpixel variant isn't zero to make room for anti-aliasing.
			let mut bitmap_size = glyph_bounds.size;
			if params.subpixel_variant.x > 0 {
				bitmap_size.width += DevicePixels(1);
			}
			if params.subpixel_variant.y > 0 {
				bitmap_size.height += DevicePixels(1);
			}
			let bitmap_size = bitmap_size;

			let mut bytes;
			let cx;
			if params.is_emoji {
				bytes = vec![0; bitmap_size.width.0 as usize * 4 * bitmap_size.height.0 as usize];
				cx = CGContext::create_bitmap_context(
					Some(bytes.as_mut_ptr() as *mut _),
					bitmap_size.width.0 as usize,
					bitmap_size.height.0 as usize,
					8,
					bitmap_size.width.0 as usize * 4,
					&CGColorSpace::create_device_rgb(),
					kCGImageAlphaPremultipliedLast,
				);
			} else {
				bytes = vec![0; bitmap_size.width.0 as usize * bitmap_size.height.0 as usize];
				cx = CGContext::create_bitmap_context(
					Some(bytes.as_mut_ptr() as *mut _),
					bitmap_size.width.0 as usize,
					bitmap_size.height.0 as usize,
					8,
					bitmap_size.width.0 as usize,
					&CGColorSpace::create_device_gray(),
					kCGImageAlphaOnly,
				);
			}

			// Move the origin to bottom left and account for scaling, this
			// makes drawing text consistent with the font-kit's raster_bounds.
			cx.translate(
				-glyph_bounds.origin.x.0 as CGFloat,
				(glyph_bounds.origin.y.0 + glyph_bounds.size.height.0) as CGFloat,
			);
			cx.scale(
				params.scale_factor as CGFloat,
				params.scale_factor as CGFloat,
			);

			let subpixel_shift = params
				.subpixel_variant
				.map(|v| v as f32 / SUBPIXEL_VARIANTS_X as f32);
			cx.set_text_drawing_mode(CGTextDrawingMode::CGTextFill);
			cx.set_allows_antialiasing(true);
			cx.set_should_antialias(true);
			cx.set_allows_font_subpixel_positioning(true);
			cx.set_should_subpixel_position_fonts(true);
			cx.set_allows_font_subpixel_quantization(false);
			cx.set_should_subpixel_quantize_fonts(false);

			if params.dilation > 0 {
				let luminance = params.dilation as f64 * 0.25;
				cx.set_should_smooth_fonts(true);
				cx.set_gray_fill_color(luminance, 1.0);
			} else {
				cx.set_gray_fill_color(0.0, 1.0);
			}
			self.fonts[params.font_id.0]
				.native_font()
				.clone_with_font_size(f32::from(params.font_size) as CGFloat)
				.draw_glyphs(
					&[params.glyph_id.0 as CGGlyph],
					&[CGPoint::new(
						(subpixel_shift.x / params.scale_factor) as CGFloat,
						(subpixel_shift.y / params.scale_factor) as CGFloat,
					)],
					cx,
				);

			if params.is_emoji {
				// Convert from RGBA with premultiplied alpha to BGRA with straight alpha.
				for pixel in bytes.chunks_exact_mut(4) {
					swap_rgba_pa_to_bgra(pixel);
				}
			}

			Ok((bitmap_size, bytes))
		}
	}

	fn layout_line(&mut self, text: &str, font_size: Pixels, font_runs: &[FontRun]) -> LineLayout {
		// Construct the attributed string, converting UTF8 ranges to UTF16 ranges.
		let mut string = CFMutableAttributedString::new();
		let mut max_ascent = 0.0f32;
		let mut max_descent = 0.0f32;

		{
			let mut text = text;
			let mut break_ligature = true;
			for run in font_runs {
				let text_run;
				(text_run, text) = text.split_at(run.len);

				let utf16_start = string.char_len(); // insert at end of string
				// note: replace_str may silently ignore codepoints it dislikes (e.g., BOM at start of string)
				string.replace_str(&CFString::new(text_run), CFRange::init(utf16_start, 0));
				let utf16_end = string.char_len();

				let length = utf16_end - utf16_start;
				let cf_range = CFRange::init(utf16_start, length);
				let font = &self.fonts[run.font_id.0];

				let font_metrics = font.metrics();
				let font_scale = f32::from(font_size) / font_metrics.units_per_em as f32;
				max_ascent = max_ascent.max(font_metrics.ascent * font_scale);
				max_descent = max_descent.max(-font_metrics.descent * font_scale);

				let font_size = if break_ligature {
					px(f32::from(font_size).next_up())
				} else {
					font_size
				};
				unsafe {
					string.set_attribute(
						cf_range,
						kCTFontAttributeName,
						&font.native_font().clone_with_font_size(font_size.into()),
					);
					if let Some(spacing) = run.letter_spacing {
						string.set_attribute(
							cf_range,
							kCTKernAttributeName,
							&CFNumber::from(f64::from(spacing.as_f32())),
						);
					}
				}
				break_ligature = !break_ligature;
			}
		}
		// Retrieve the glyphs from the shaped line, converting UTF16 offsets to UTF8 offsets.
		let line = CTLine::new_with_attributed_string(string.as_concrete_TypeRef());
		let glyph_runs = line.glyph_runs();
		let mut runs = <Vec<ShapedRun>>::with_capacity(glyph_runs.len() as usize);
		let mut ix_converter = StringIndexConverter::new(text);
		for run in glyph_runs.into_iter() {
			let attributes = run.attributes().unwrap();
			let font = unsafe {
				attributes
					.get(kCTFontAttributeName)
					.downcast::<CTFont>()
					.unwrap()
			};
			let font_id = self.id_for_native_font(font);

			let glyphs = match runs.last_mut() {
				Some(run) if run.font_id == font_id => &mut run.glyphs,
				_ => {
					runs.push(ShapedRun {
						font_id,
						glyphs: Vec::with_capacity(run.glyph_count().try_into().unwrap_or(0)),
					});
					&mut runs.last_mut().unwrap().glyphs
				}
			};
			for ((&glyph_id, position), &glyph_utf16_ix) in run
				.glyphs()
				.iter()
				.zip(run.positions().iter())
				.zip(run.string_indices().iter())
			{
				let glyph_utf16_ix = usize::try_from(glyph_utf16_ix).unwrap();
				if ix_converter.utf16_ix > glyph_utf16_ix {
					// We cannot reuse current index converter, as it can only seek forward. Restart the search.
					ix_converter = StringIndexConverter::new(text);
				}
				ix_converter.advance_to_utf16_ix(glyph_utf16_ix);
				glyphs.push(ShapedGlyph {
					id: GlyphId(glyph_id as u32),
					position: point(position.x as f32, position.y as f32).map(px),
					index: ix_converter.utf8_ix,
					is_emoji: self.is_emoji(font_id),
				});
			}
		}
		let typographic_bounds = line.get_typographic_bounds();
		LineLayout {
			runs,
			font_size,
			width: typographic_bounds.width.into(),
			ascent: max_ascent.into(),
			descent: max_descent.into(),
			len: text.len(),
		}
	}
}

#[derive(Debug, Clone)]
struct StringIndexConverter<'a> {
	text: &'a str,
	/// Index in UTF-8 bytes
	utf8_ix: usize,
	/// Index in UTF-16 code units
	utf16_ix: usize,
}

impl<'a> StringIndexConverter<'a> {
	fn new(text: &'a str) -> Self {
		Self {
			text,
			utf8_ix: 0,
			utf16_ix: 0,
		}
	}

	fn advance_to_utf16_ix(&mut self, utf16_target: usize) {
		for (ix, c) in self.text[self.utf8_ix..].char_indices() {
			if self.utf16_ix >= utf16_target {
				self.utf8_ix += ix;
				return;
			}
			self.utf16_ix += c.len_utf16();
		}
		self.utf8_ix = self.text.len();
	}
}

fn font_kit_metrics_to_metrics(metrics: Metrics) -> FontMetrics {
	FontMetrics {
		units_per_em: metrics.units_per_em,
		ascent: metrics.ascent,
		descent: metrics.descent,
		line_gap: metrics.line_gap,
		underline_position: metrics.underline_position,
		underline_thickness: metrics.underline_thickness,
		cap_height: metrics.cap_height,
		x_height: metrics.x_height,
		bounding_box: bounds_from_rect(metrics.bounding_box),
	}
}

fn bounds_from_rect(rect: RectF) -> Bounds<f32> {
	Bounds {
		origin: point(rect.origin_x(), rect.origin_y()),
		size: size(rect.width(), rect.height()),
	}
}

fn bounds_from_rect_i(rect: RectI) -> Bounds<DevicePixels> {
	Bounds {
		origin: point(DevicePixels(rect.origin_x()), DevicePixels(rect.origin_y())),
		size: size(DevicePixels(rect.width()), DevicePixels(rect.height())),
	}
}

// impl From<Vector2I> for Size<DevicePixels> {
//     fn from(value: Vector2I) -> Self {
//         size(value.x().into(), value.y().into())
//     }
// }

// impl From<RectI> for Bounds<i32> {
//     fn from(rect: RectI) -> Self {
//         Bounds {
//             origin: point(rect.origin_x(), rect.origin_y()),
//             size: size(rect.width(), rect.height()),
//         }
//     }
// }

// impl From<Point<u32>> for Vector2I {
//     fn from(size: Point<u32>) -> Self {
//         Vector2I::new(size.x as i32, size.y as i32)
//     }
// }

fn size_from_vector2f(vec: Vector2F) -> Size<f32> {
	size(vec.x(), vec.y())
}

fn fontkit_weight(value: FontWeight) -> FontkitWeight {
	FontkitWeight(value.0)
}

fn fontkit_style(style: FontStyle) -> FontkitStyle {
	match style {
		FontStyle::Normal => FontkitStyle::Normal,
		FontStyle::Italic => FontkitStyle::Italic,
		FontStyle::Oblique => FontkitStyle::Oblique,
	}
}

// Some fonts may have no attributes despite `core_text` requiring them (and panicking).
// This is the same version as `core_text` has without `expect` calls.
mod lenient_font_attributes {
	use core_foundation::{
		base::{CFRetain, CFType, TCFType},
		string::{CFString, CFStringRef},
	};
	use core_text::font_descriptor::{
		CTFontDescriptor, CTFontDescriptorCopyAttribute, kCTFontFamilyNameAttribute,
	};

	pub fn family_name(descriptor: &CTFontDescriptor) -> Option<String> {
		unsafe { get_string_attribute(descriptor, kCTFontFamilyNameAttribute) }
	}

	fn get_string_attribute(
		descriptor: &CTFontDescriptor,
		attribute: CFStringRef,
	) -> Option<String> {
		unsafe {
			let value = CTFontDescriptorCopyAttribute(descriptor.as_concrete_TypeRef(), attribute);
			if value.is_null() {
				return None;
			}

			let value = CFType::wrap_under_create_rule(value);
			assert!(value.instance_of::<CFString>());
			let s = wrap_under_get_rule(value.as_CFTypeRef() as CFStringRef);
			Some(s.to_string())
		}
	}

	unsafe fn wrap_under_get_rule(reference: CFStringRef) -> CFString {
		unsafe {
			assert!(!reference.is_null(), "Attempted to create a NULL object.");
			let reference = CFRetain(reference as *const ::std::os::raw::c_void) as CFStringRef;
			TCFType::wrap_under_create_rule(reference)
		}
	}
}

#[cfg(test)]
mod tests {
	use crate::MacTextSystem;
	use gpui::{FontRun, GlyphId, PlatformTextSystem, font, px};

	#[test]
	fn test_layout_line_bom_char() {
		let fonts = MacTextSystem::new();
		let font_id = fonts.font_id(&font("Helvetica")).unwrap();
		let line = "\u{feff}";
		let mut style = FontRun {
			font_id,
			len: line.len(),
			letter_spacing: None,
		};

		let layout = fonts.layout_line(line, px(16.), &[style]);
		assert_eq!(layout.len, line.len());
		assert!(layout.runs.is_empty());

		let line = "a\u{feff}b";
		style.len = line.len();
		let layout = fonts.layout_line(line, px(16.), &[style]);
		assert_eq!(layout.len, line.len());
		assert_eq!(layout.runs.len(), 1);
		assert_eq!(layout.runs[0].glyphs.len(), 2);
		assert_eq!(layout.runs[0].glyphs[0].id, GlyphId(68u32)); // a
		// There's no glyph for \u{feff}
		assert_eq!(layout.runs[0].glyphs[1].id, GlyphId(69u32)); // b

		let line = "\u{feff}ab";
		let font_runs = &[
			FontRun {
				len: "\u{feff}".len(),
				font_id,
				letter_spacing: None,
			},
			FontRun {
				len: "ab".len(),
				font_id,
				letter_spacing: None,
			},
		];
		let layout = fonts.layout_line(line, px(16.), font_runs);
		assert_eq!(layout.len, line.len());
		assert_eq!(layout.runs.len(), 1);
		assert_eq!(layout.runs[0].glyphs.len(), 2);
		// There's no glyph for \u{feff}
		assert_eq!(layout.runs[0].glyphs[0].id, GlyphId(68u32)); // a
		assert_eq!(layout.runs[0].glyphs[1].id, GlyphId(69u32)); // b
	}

	#[test]
	fn test_layout_line_zwnj_insertion() {
		let fonts = MacTextSystem::new();
		let font_id = fonts.font_id(&font("Helvetica")).unwrap();

		let text = "hello world";
		let font_runs = &[
			FontRun {
				font_id,
				len: 5,
				letter_spacing: None,
			}, // "hello"
			FontRun {
				font_id,
				len: 6,
				letter_spacing: None,
			}, // " world"
		];

		let layout = fonts.layout_line(text, px(16.), font_runs);
		assert_eq!(layout.len, text.len());

		for run in &layout.runs {
			for glyph in &run.glyphs {
				assert!(
					glyph.index < text.len(),
					"Glyph index {} is out of bounds for text length {}",
					glyph.index,
					text.len()
				);
			}
		}

		// Test with different font runs - should not insert ZWNJ
		let font_id2 = fonts.font_id(&font("Times")).unwrap_or(font_id);
		let font_runs_different = &[
			FontRun {
				font_id,
				len: 5,
				letter_spacing: None,
			}, // "hello"
			// " world"
			FontRun {
				font_id: font_id2,
				len: 6,
				letter_spacing: None,
			},
		];

		let layout2 = fonts.layout_line(text, px(16.), font_runs_different);
		assert_eq!(layout2.len, text.len());

		for run in &layout2.runs {
			for glyph in &run.glyphs {
				assert!(
					glyph.index < text.len(),
					"Glyph index {} is out of bounds for text length {}",
					glyph.index,
					text.len()
				);
			}
		}
	}

	#[test]
	fn test_layout_line_zwnj_edge_cases() {
		let fonts = MacTextSystem::new();
		let font_id = fonts.font_id(&font("Helvetica")).unwrap();

		let text = "hello";
		let font_runs = &[FontRun {
			font_id,
			len: 5,
			letter_spacing: None,
		}];
		let layout = fonts.layout_line(text, px(16.), font_runs);
		assert_eq!(layout.len, text.len());

		let text = "abc";
		let font_runs = &[
			FontRun {
				font_id,
				len: 1,
				letter_spacing: None,
			}, // "a"
			FontRun {
				font_id,
				len: 1,
				letter_spacing: None,
			}, // "b"
			FontRun {
				font_id,
				len: 1,
				letter_spacing: None,
			}, // "c"
		];
		let layout = fonts.layout_line(text, px(16.), font_runs);
		assert_eq!(layout.len, text.len());

		for run in &layout.runs {
			for glyph in &run.glyphs {
				assert!(
					glyph.index < text.len(),
					"Glyph index {} is out of bounds for text length {}",
					glyph.index,
					text.len()
				);
			}
		}

		// Test with empty text
		let text = "";
		let font_runs = &[];
		let layout = fonts.layout_line(text, px(16.), font_runs);
		assert_eq!(layout.len, 0);
		assert!(layout.runs.is_empty());
	}
}