//! This module implements my own bitmap and layout based system.
//!
//! I created those as a result to my annoyance of how bad / limited
//! plotters is at rendering text and creating layouts in a clean manner.
//!
//! There's still stuff to be implemented here, like a cache for glyphs and
//! whatnot, but this does run pretty stably for the b30 renderer.

use anyhow::anyhow;
use freetype::{
	bitmap::PixelMode,
	face::{KerningMode, LoadFlag},
	ffi::{FT_Set_Var_Design_Coordinates, FT_GLYPH_BBOX_PIXELS},
	Bitmap, BitmapGlyph, Face, Glyph, StrokerLineCap, StrokerLineJoin,
};
use image::{GenericImage, RgbImage, RgbaImage};
use num::traits::Euclid;

use crate::{assets::FREETYPE_LIB, context::Error};

// {{{ Color
#[derive(Debug, Clone, Copy)]
pub struct Color(pub u8, pub u8, pub u8, pub u8);

impl Color {
	pub const BLACK: Self = Self::from_rgb_int(0x000000);
	pub const WHITE: Self = Self::from_rgb_int(0xffffff);

	#[inline]
	pub const fn from_rgba_int(i: u32) -> Self {
		Self(
			(i >> 24) as u8,
			((i >> 16) & 0xff) as u8,
			((i >> 8) & 0xff) as u8,
			(i & 0xff) as u8,
		)
	}

	#[inline]
	pub const fn from_rgb_int(i: u32) -> Self {
		Self::from_rgba_int((i << 8) + 0xff)
	}

	#[inline]
	pub const fn from_bytes(bytes: [u8; 4]) -> Self {
		Self(bytes[0], bytes[1], bytes[2], bytes[3])
	}

	#[inline]
	pub fn alpha(mut self, a: u8) -> Self {
		self.3 = a;
		self
	}

	#[inline]
	pub fn distance(self, other: Self) -> f32 {
		let dr = self.0 as f32 - other.0 as f32;
		let dg = self.1 as f32 - other.1 as f32;
		let db = self.2 as f32 - other.2 as f32;
		(dr * dr + dg * dg + db * db).sqrt()
	}
}
// }}}
// {{{ Rect
#[derive(Debug, Clone, Copy)]
pub struct Rect {
	pub x: i32,
	pub y: i32,
	pub width: u32,
	pub height: u32,
}

impl Rect {
	#[inline]
	pub fn new(x: i32, y: i32, width: u32, height: u32) -> Self {
		Self {
			x,
			y,
			width,
			height,
		}
	}

	#[inline]
	pub fn from_extremes(x_min: i32, y_min: i32, x_max: i32, y_max: i32) -> Self {
		Self::new(x_min, y_min, (x_max - x_min) as u32, (y_max - y_min) as u32)
	}

	#[inline]
	pub fn from_image(image: &impl GenericImage) -> Self {
		Self::new(0, 0, image.width(), image.height())
	}

	#[inline]
	pub fn scaled(&self, scale: u32) -> Self {
		Self::new(self.x, self.y, self.width * scale, self.height * scale)
	}

	#[inline]
	pub fn align(&self, alignment: (Align, Align), pos: Position) -> Position {
		(
			pos.0 - alignment.0.scale(self.width) as i32,
			pos.1 - alignment.1.scale(self.height) as i32,
		)
	}

	#[inline]
	pub fn align_whole(&self, alignment: (Align, Align), pos: Position) -> Self {
		let pos = self.align(alignment, pos);
		Self::new(pos.0, pos.1, self.width, self.height)
	}

	#[inline]
	pub fn center(&self) -> Position {
		(
			self.x + self.width as i32 / 2,
			self.y + self.height as i32 / 2,
		)
	}

	#[inline]
	pub fn top_left(&self) -> Position {
		(self.x, self.y)
	}
}
// }}}
// {{{ Align
#[allow(dead_code)]
#[derive(Debug, Clone, Copy)]
pub enum Align {
	Start,
	Center,
	End,
}

impl Align {
	#[inline]
	pub fn scale(self, dist: u32) -> u32 {
		match self {
			Self::Start => 0,
			Self::Center => dist / 2,
			Self::End => dist,
		}
	}
}
// }}}
// {{{ Other types
pub type Position = (i32, i32);

fn float_to_ft_fixed(f: f32) -> i64 {
	(f * 64.0) as i64
}

#[derive(Debug, Clone, Copy)]
pub struct TextStyle {
	pub size: u32,
	pub weight: Option<u32>,
	pub color: Color,
	pub align: (Align, Align),
	pub stroke: Option<(Color, f32)>,
	pub drop_shadow: Option<(Color, Position)>,
}
// }}}
// {{{ BitmapCanvas
pub struct BitmapCanvas {
	pub buffer: Box<[u8]>,
	pub width: u32,
}

impl BitmapCanvas {
	#[inline]
	pub fn height(&self) -> u32 {
		self.buffer.len() as u32 / 3 / self.width
	}

	// {{{ Draw pixel
	pub fn set_pixel(&mut self, pos: (u32, u32), color: Color) {
		let index = 3 * (pos.1 * self.width + pos.0) as usize;
		let alpha = color.3 as u32;
		self.buffer[index + 0] =
			((alpha * color.0 as u32 + (255 - alpha) * self.buffer[index + 0] as u32) / 255) as u8;
		self.buffer[index + 1] =
			((alpha * color.1 as u32 + (255 - alpha) * self.buffer[index + 1] as u32) / 255) as u8;
		self.buffer[index + 2] =
			((alpha * color.2 as u32 + (255 - alpha) * self.buffer[index + 2] as u32) / 255) as u8;
	}
	// }}}
	// {{{ Draw RGB image
	/// Draws a bitmap image with no alpha channel.
	pub fn blit_rbg(&mut self, pos: Position, (iw, ih): (u32, u32), src: &[u8]) {
		let iw = iw as i32;
		let ih = ih as i32;
		let width = self.width as i32;
		let height = self.height() as i32;

		let x_start = 0.max(-pos.0);
		let y_start = 0.max(-pos.1);
		let x_end = iw.min(width - pos.0);
		let y_end = ih.min(height - pos.1);

		for dx in x_start..x_end {
			for dy in y_start..y_end {
				let x = pos.0 + dx;
				let y = pos.1 + dy;

				let r = src[(dx + dy * iw) as usize * 3];
				let g = src[(dx + dy * iw) as usize * 3 + 1];
				let b = src[(dx + dy * iw) as usize * 3 + 2];

				let color = Color(r, g, b, 0xff);

				self.set_pixel((x as u32, y as u32), color);
			}
		}
	}
	// }}}
	// {{{ Draw RGBA image
	/// Draws a bitmap image taking care of the alpha channel.
	pub fn blit_rbga(&mut self, pos: Position, (iw, ih): (u32, u32), src: &[u8]) {
		let iw = iw as i32;
		let ih = ih as i32;
		let width = self.width as i32;
		let height = self.height() as i32;

		let x_start = 0.max(-pos.0);
		let y_start = 0.max(-pos.1);
		let x_end = iw.min(width - pos.0);
		let y_end = ih.min(height - pos.1);

		for dx in x_start..x_end {
			for dy in y_start..y_end {
				let x = pos.0 + dx;
				let y = pos.1 + dy;

				let r = src[(dx + dy * iw) as usize * 4];
				let g = src[(dx + dy * iw) as usize * 4 + 1];
				let b = src[(dx + dy * iw) as usize * 4 + 2];
				let a = src[(dx + dy * iw) as usize * 4 + 3];

				let color = Color(r, g, b, a);

				self.set_pixel((x as u32, y as u32), color);
			}
		}
	}
	// }}}
	// {{{ Draw scaled up RBGA image
	pub fn blit_rbga_scaled_up(
		&mut self,
		pos: Position,
		(iw, ih): (u32, u32),
		src: &[u8],
		scale: u32,
	) {
		let scale = scale as i32;

		let iw = iw as i32;
		let ih = ih as i32;
		let width = self.width as i32;
		let height = self.height() as i32;

		let x_start = pos.0.max(0);
		let y_start = pos.1.max(0);
		let x_end = (pos.0 + iw * scale).min(width);
		let y_end = (pos.1 + ih * scale).min(height);

		for x in x_start..x_end {
			for y in y_start..y_end {
				// NOTE: I could instead keep separate counters.
				// It would introduce an additional if statement,
				// but would not perform division.
				let dx = (x - pos.0) / scale;
				let dy = (y - pos.1) / scale;
				let r = src[(dx + dy * iw) as usize * 4];
				let g = src[(dx + dy * iw) as usize * 4 + 1];
				let b = src[(dx + dy * iw) as usize * 4 + 2];
				let a = src[(dx + dy * iw) as usize * 4 + 3];

				let color = Color(r, g, b, a);

				self.set_pixel((x as u32, y as u32), color);
			}
		}
	}
	// }}}
	// {{{ Fill
	/// Fill with solid color
	pub fn fill(&mut self, pos: Position, (iw, ih): (u32, u32), color: Color) {
		let height = self.height();
		for dx in 0..iw {
			for dy in 0..ih {
				let x = pos.0 + dx as i32;
				let y = pos.1 + dy as i32;
				if x >= 0 && (x as u32) < self.width && y >= 0 && (y as u32) < height {
					self.set_pixel((x as u32, y as u32), color);
				}
			}
		}
	}
	// }}}
	// {{{ Draw text
	pub fn plan_text_rendering(
		pos: Position,
		faces: &mut [&mut Face],
		style: TextStyle,
		text: &str,
	) -> Result<(Position, Rect, Vec<(i64, Glyph)>), Error> {
		// {{{ Control weight
		if let Some(weight) = style.weight {
			for face in faces.iter_mut() {
				unsafe {
					let raw = face.raw_mut() as *mut _;
					let slice = [(weight as i64) << 16];

					// {{{ Debug logging
					// let mut amaster = 0 as *mut FT_MM_Var;
					// FT_Get_MM_Var(raw, &mut amaster as *mut _);
					// println!("{:?}", *amaster);
					// println!("{:?}", *(*amaster).axis);
					// println!("{:?}", *(*amaster).namedstyle);
					// }}}

					// Set variable weight
					let _err = FT_Set_Var_Design_Coordinates(raw, 3, slice.as_ptr());
					// Some fonts are not variable, so we just ignore errors :/
					// if err != FT_Err_Ok {
					// 	let err: FtResult<_> = Err(err.into());
					// 	err?;
					// }
				}
			}
		}
		// }}}

		for face in faces.iter_mut() {
			face.set_char_size((style.size << 6) as isize, 0, 0, 0)?;
		}

		// {{{ Compute layout
		let mut pen_x = 0;
		let kerning: Vec<_> = faces.iter().map(|f| f.has_kerning()).collect();
		let mut previous = None;
		let mut data = Vec::new();

		for c in text.chars() {
			let c = match c {
				'～' => '~',
				c => c,
			};

			let (face_index, glyph_index) = faces
				.iter()
				.enumerate()
				.find_map(|(i, face)| {
					let glyph_index = face.get_char_index(c as usize)?;
					Some((i, glyph_index))
				})
				.ok_or_else(|| {
					anyhow!("Could not get glyph index for char '{}' in \"{}\"", c, text)
				})?;

			let face = &mut faces[face_index];
			if let Some((prev_face_index, prev_glyth_index)) = previous
				&& prev_face_index == face_index
				&& kerning[face_index]
			{
				let delta =
					face.get_kerning(prev_glyth_index, glyph_index, KerningMode::KerningDefault)?;
				pen_x += delta.x >> 6; // we shift to get rid of sub-pixel accuracy
			}

			face.load_glyph(glyph_index, LoadFlag::DEFAULT)?;

			data.push((pen_x, face.glyph().get_glyph()?));
			pen_x += face.glyph().advance().x >> 6;
			previous = Some((face_index, glyph_index));
		}

		// }}}
		// {{{ Find bounding box
		let mut x_min = 32000;
		let mut y_min = 32000;
		let mut x_max = -32000;
		let mut y_max = -32000;

		for (pen_x, glyph) in &data {
			let mut bbox = glyph.get_cbox(FT_GLYPH_BBOX_PIXELS);

			bbox.xMin += pen_x;
			bbox.xMax += pen_x;

			if bbox.xMin < x_min {
				x_min = bbox.xMin
			}

			if bbox.xMax > x_max {
				x_max = bbox.xMax
			}

			if bbox.yMin < y_min {
				y_min = bbox.yMin
			}

			if bbox.yMax > y_max {
				y_max = bbox.yMax
			}
		}

		// Check that we really grew the string bbox
		if x_min > x_max {
			x_min = 0;
			x_max = 0;
			y_min = 0;
			y_max = 0;
		}

		let bbox = Rect::from_extremes(x_min as i32, y_min as i32, x_max as i32, y_max as i32);
		let pos = bbox.align(style.align, pos);
		// }}}

		Ok((pos, bbox, data))
	}

	/// Render text
	pub fn text(
		&mut self,
		pos: Position,
		faces: &mut [&mut Face],
		style: TextStyle,
		text: &str,
	) -> Result<(), Error> {
		let (pos, bbox, data) = Self::plan_text_rendering(pos, faces, style, text)?;

		// {{{ Render glyphs
		for (pos_x, glyph) in &data {
			let b_glyph = glyph.to_bitmap(freetype::RenderMode::Normal, None)?;
			let bitmap = b_glyph.bitmap();
			let pixel_mode = bitmap.pixel_mode()?;
			assert_eq!(pixel_mode, PixelMode::Gray);

			let char_pos = (
				pos.0 + *pos_x as i32 - bbox.x,
				pos.1 + bbox.height as i32 + bbox.y,
			);

			if let Some((shadow_color, offset)) = style.drop_shadow {
				let char_pos = (char_pos.0 + offset.0, char_pos.1 + offset.1);
				self.blit_glyph(&b_glyph, &bitmap, char_pos, shadow_color);
			}

			if let Some((stroke_color, stroke_width)) = style.stroke {
				// {{{ Create stroke
				let stroker = FREETYPE_LIB.with(|lib| lib.new_stroker())?;
				stroker.set(
					float_to_ft_fixed(stroke_width),
					StrokerLineCap::Round,
					StrokerLineJoin::Round,
					0,
				);

				let sglyph = glyph.stroke(&stroker)?;
				let sb_glyph = sglyph.to_bitmap(freetype::RenderMode::Normal, None)?;
				let sbitmap = sb_glyph.bitmap();
				let spixel_mode = sbitmap.pixel_mode()?;
				assert_eq!(spixel_mode, PixelMode::Gray);
				// }}}

				self.blit_glyph(&sb_glyph, &sbitmap, char_pos, stroke_color);
			}

			self.blit_glyph(&b_glyph, &bitmap, char_pos, style.color);
		}
		// }}}

		Ok(())
	}
	// }}}
	// {{{ Blit glyph
	pub fn blit_glyph(
		&mut self,
		b_glyph: &BitmapGlyph,
		bitmap: &Bitmap,
		pos: Position,
		color: Color,
	) {
		let iw = bitmap.width();
		let ih = bitmap.rows();
		let height = self.buffer.len() as u32 / 3 / self.width;
		let src = bitmap.buffer();

		for dx in 0..iw {
			for dy in 0..ih {
				let x = pos.0 + dx as i32 + b_glyph.left();
				let y = pos.1 + dy as i32 - b_glyph.top();

				// TODO: gamma correction
				if x >= 0 && (x as u32) < self.width && y >= 0 && (y as u32) < height {
					let gray = src[(dx + dy * iw) as usize];

					let r = color.0;
					let g = color.1;
					let b = color.2;
					let a = ((color.3 as u32 * gray as u32) / 0xff) as u8;

					let color = Color(r, g, b, a);

					self.set_pixel((x as u32, y as u32), color);
				}
			}
		}
	}
	// }}}

	#[inline]
	pub fn new(width: u32, height: u32) -> Self {
		let buffer = vec![u8::MAX; 3 * (width * height) as usize].into_boxed_slice();
		Self { buffer, width }
	}
}
// }}}
// {{{ Layout types
#[derive(Clone, Copy, Debug)]
pub struct LayoutBox {
	relative_to: Option<(LayoutBoxId, i32, i32)>,
	pub width: u32,
	pub height: u32,
}

#[derive(Clone, Copy, PartialEq, Eq, Debug)]
pub struct LayoutBoxId(usize);

#[derive(Default, Debug)]
pub struct LayoutManager {
	boxes: Vec<LayoutBox>,
}

pub struct LayoutDrawer {
	pub layout: LayoutManager,
	pub canvas: BitmapCanvas,
}

impl LayoutManager {
	// {{{ Trivial box creation
	pub fn make_box(&mut self, width: u32, height: u32) -> LayoutBoxId {
		let id = self.boxes.len();
		self.boxes.push(LayoutBox {
			relative_to: None,
			width,
			height,
		});

		LayoutBoxId(id)
	}

	pub fn make_relative_box(
		&mut self,
		to: LayoutBoxId,
		x: i32,
		y: i32,
		width: u32,
		height: u32,
	) -> LayoutBoxId {
		let id = self.make_box(width, height);
		self.edit_to_relative(id, to, x, y);

		id
	}
	// }}}
	// {{{ Chage box to be relative
	pub fn edit_to_relative(
		&mut self,
		id: LayoutBoxId,
		id_relative_to: LayoutBoxId,
		x: i32,
		y: i32,
	) {
		let current = self.boxes[id.0];

		if let Some((current_points_to, dx, dy)) = current.relative_to
			&& current_points_to != id_relative_to
		{
			self.edit_to_relative(current_points_to, id_relative_to, x - dx, y - dy);
		} else {
			self.boxes[id.0].relative_to = Some((id_relative_to, x, y));
		}

		{
			let a = self.lookup(id);
			let b = self.lookup(id_relative_to);
			assert_eq!((a.x - b.x, a.y - b.y), (x, y));
		}
	}
	// }}}
	// {{{ Margins
	#[inline]
	pub fn margin(&mut self, id: LayoutBoxId, t: i32, r: i32, b: i32, l: i32) -> LayoutBoxId {
		let inner = self.boxes[id.0];
		let out = self.make_box(
			(inner.width as i32 + l + r) as u32,
			(inner.height as i32 + t + b) as u32,
		);
		self.edit_to_relative(id, out, l, t);
		out
	}

	#[inline]
	pub fn margin_xy(&mut self, inner: LayoutBoxId, x: i32, y: i32) -> LayoutBoxId {
		self.margin(inner, y, x, y, x)
	}

	#[inline]
	pub fn margin_uniform(&mut self, inner: LayoutBoxId, amount: i32) -> LayoutBoxId {
		self.margin(inner, amount, amount, amount, amount)
	}
	// }}}
	// {{{ Glueing
	#[inline]
	pub fn glue_horizontally(
		&mut self,
		first_id: LayoutBoxId,
		second_id: LayoutBoxId,
	) -> LayoutBoxId {
		let first = self.boxes[first_id.0];
		let second = self.boxes[second_id.0];
		let id = self.make_box(first.width.max(second.width), first.height + second.height);

		self.edit_to_relative(first_id, id, 0, 0);
		self.edit_to_relative(second_id, id, 0, first.height as i32);
		id
	}

	#[inline]
	pub fn glue_vertically(
		&mut self,
		first_id: LayoutBoxId,
		second_id: LayoutBoxId,
	) -> LayoutBoxId {
		let first = self.boxes[first_id.0];
		let second = self.boxes[second_id.0];
		let id = self.make_box(first.width + second.width, first.height.max(second.height));

		self.edit_to_relative(first_id, id, 0, 0);
		self.edit_to_relative(second_id, id, first.width as i32, 0);
		id
	}
	// }}}
	// {{{ Repeating
	pub fn repeated_evenly(
		&mut self,
		id: LayoutBoxId,
		amount: (u32, u32),
	) -> (LayoutBoxId, impl Iterator<Item = Position>) {
		let inner = self.boxes[id.0];
		let outer_id = self.make_box(inner.width * amount.0, inner.height * amount.1);
		self.edit_to_relative(id, outer_id, 0, 0);

		(
			outer_id,
			(0..amount.0 * amount.1).into_iter().map(move |i| {
				let (y, x) = i.div_rem_euclid(&amount.0);
				((x * inner.width) as i32, (y * inner.height) as i32)
			}),
		)
	}
	// }}}
	// {{{ Lookup box
	pub fn lookup(&self, id: LayoutBoxId) -> Rect {
		let current = self.boxes[id.0];
		if let Some((to, dx, dy)) = current.relative_to {
			let r = self.lookup(to);
			Rect::new(r.x + dx, r.y + dy, current.width, current.height)
		} else {
			Rect::new(0, 0, current.width, current.height)
		}
	}

	#[inline]
	pub fn width(&self, id: LayoutBoxId) -> u32 {
		self.boxes[id.0].width
	}

	#[inline]
	pub fn height(&self, id: LayoutBoxId) -> u32 {
		self.boxes[id.0].height
	}

	// }}}
	// {{{ Alignment
	#[inline]
	pub fn position_relative_to(&self, id: LayoutBoxId, pos: Position) -> Position {
		let current = self.lookup(id);
		((pos.0 as i32 + current.x), (pos.1 as i32 + current.y))
	}

	#[inline]
	pub fn align(&self, id: LayoutBoxId, align: (Align, Align), pos: Position) -> Position {
		self.lookup(id).align(align, pos)
	}
	// }}}
}

impl LayoutDrawer {
	#[inline]
	pub fn new(layout: LayoutManager, canvas: BitmapCanvas) -> Self {
		Self { layout, canvas }
	}

	// {{{ Drawing
	// {{{ Draw pixel
	#[inline]
	pub fn set_pixel(&mut self, id: LayoutBoxId, pos: (u32, u32), color: Color) {
		let pos = self
			.layout
			.position_relative_to(id, (pos.0 as i32, pos.1 as i32));
		self.canvas.set_pixel((pos.0 as u32, pos.1 as u32), color);
	}
	// }}}
	// {{{ Draw images
	/// Draws a bitmap image taking with no alpha channel.
	#[inline]
	pub fn blit_rbg(&mut self, id: LayoutBoxId, pos: Position, image: &RgbImage) {
		let pos = self.layout.position_relative_to(id, pos);
		self.canvas
			.blit_rbg(pos, image.dimensions(), image.as_raw());
	}

	/// Draws a bitmap image taking care of the alpha channel.
	#[inline]
	pub fn blit_rbga(&mut self, id: LayoutBoxId, pos: Position, image: &RgbaImage) {
		let pos = self.layout.position_relative_to(id, pos);
		self.canvas
			.blit_rbga(pos, image.dimensions(), image.as_raw());
	}

	#[inline]
	pub fn blit_rbg_scaled_up(
		&mut self,
		id: LayoutBoxId,
		pos: Position,
		dims: (u32, u32),
		src: &[u8],
		scale: u32,
	) {
		let pos = self.layout.position_relative_to(id, pos);
		self.canvas.blit_rbga_scaled_up(pos, dims, src, scale);
	}
	// }}}
	// {{{ Fill
	/// Fills with solid color
	#[inline]
	pub fn fill(&mut self, id: LayoutBoxId, color: Color) {
		let current = self.layout.lookup(id);
		self.canvas.fill(
			(current.x, current.y),
			(current.width, current.height),
			color,
		);
	}
	// }}}
	// {{{ Draw text
	/// Render text
	#[inline]
	pub fn text(
		&mut self,
		id: LayoutBoxId,
		pos: Position,
		faces: &mut [&mut Face],
		style: TextStyle,
		text: &str,
	) -> Result<(), Error> {
		let pos = self.layout.position_relative_to(id, pos);
		self.canvas.text(pos, faces, style, text)
	}
	// }}}
	// }}}
}
// }}}