azul-layout 0.0.5

use alloc::{boxed::Box, collections::btree_map::BTreeMap, rc::Rc, vec::Vec};

use allsorts_subset_browser::{
    binary::read::ReadScope,
    font_data::FontData,
    gsub::RawGlyphFlags,
    layout::{GDEFTable, LayoutCache, GPOS, GSUB},
    tables::{
        cmap::{owned::CmapSubtable as OwnedCmapSubtable, CmapSubtable},
        glyf::{BoundingBox, GlyfRecord, GlyfTable, Glyph},
        loca::{LocaOffsets, LocaTable},
        FontTableProvider, HeadTable, HheaTable, MaxpTable,
    },
};
use azul_core::app_resources::{
    Advance, Anchor, FontMetrics, GlyphInfo, GlyphOrigin, Placement, RawGlyph, VariationSelector,
};
use tinyvec::tiny_vec;

pub fn get_font_metrics(font_bytes: &[u8], font_index: usize) -> FontMetrics {
    #[derive(Default)]
    struct Os2Info {
        x_avg_char_width: i16,
        us_weight_class: u16,
        us_width_class: u16,
        fs_type: u16,
        y_subscript_x_size: i16,
        y_subscript_y_size: i16,
        y_subscript_x_offset: i16,
        y_subscript_y_offset: i16,
        y_superscript_x_size: i16,
        y_superscript_y_size: i16,
        y_superscript_x_offset: i16,
        y_superscript_y_offset: i16,
        y_strikeout_size: i16,
        y_strikeout_position: i16,
        s_family_class: i16,
        panose: [u8; 10],
        ul_unicode_range1: u32,
        ul_unicode_range2: u32,
        ul_unicode_range3: u32,
        ul_unicode_range4: u32,
        ach_vend_id: u32,
        fs_selection: u16,
        us_first_char_index: u16,
        us_last_char_index: u16,
        s_typo_ascender: Option<i16>,
        s_typo_descender: Option<i16>,
        s_typo_line_gap: Option<i16>,
        us_win_ascent: Option<u16>,
        us_win_descent: Option<u16>,
        ul_code_page_range1: Option<u32>,
        ul_code_page_range2: Option<u32>,
        sx_height: Option<i16>,
        s_cap_height: Option<i16>,
        us_default_char: Option<u16>,
        us_break_char: Option<u16>,
        us_max_context: Option<u16>,
        us_lower_optical_point_size: Option<u16>,
        us_upper_optical_point_size: Option<u16>,
    }

    let scope = ReadScope::new(font_bytes);
    let font_file = match scope.read::<FontData<'_>>() {
        Ok(o) => o,
        Err(_) => return FontMetrics::default(),
    };
    let provider = match font_file.table_provider(font_index) {
        Ok(o) => o,
        Err(_) => return FontMetrics::default(),
    };
    let font = match allsorts_subset_browser::font::Font::new(provider).ok() {
        Some(s) => s,
        _ => return FontMetrics::default(),
    };

    // read the HHEA table to get the metrics for horizontal layout
    let hhea_table = &font.hhea_table;
    let head_table = match font.head_table().ok() {
        Some(Some(s)) => s,
        _ => return FontMetrics::default(),
    };

    let os2_table = match font.os2_table().ok() {
        Some(Some(s)) => Os2Info {
            x_avg_char_width: s.x_avg_char_width,
            us_weight_class: s.us_weight_class,
            us_width_class: s.us_width_class,
            fs_type: s.fs_type,
            y_subscript_x_size: s.y_subscript_x_size,
            y_subscript_y_size: s.y_subscript_y_size,
            y_subscript_x_offset: s.y_subscript_x_offset,
            y_subscript_y_offset: s.y_subscript_y_offset,
            y_superscript_x_size: s.y_superscript_x_size,
            y_superscript_y_size: s.y_superscript_y_size,
            y_superscript_x_offset: s.y_superscript_x_offset,
            y_superscript_y_offset: s.y_superscript_y_offset,
            y_strikeout_size: s.y_strikeout_size,
            y_strikeout_position: s.y_strikeout_position,
            s_family_class: s.s_family_class,
            panose: s.panose,
            ul_unicode_range1: s.ul_unicode_range1,
            ul_unicode_range2: s.ul_unicode_range2,
            ul_unicode_range3: s.ul_unicode_range3,
            ul_unicode_range4: s.ul_unicode_range4,
            ach_vend_id: s.ach_vend_id,
            fs_selection: s.fs_selection.bits(),
            us_first_char_index: s.us_first_char_index,
            us_last_char_index: s.us_last_char_index,

            s_typo_ascender: s.version0.as_ref().map(|q| q.s_typo_ascender),
            s_typo_descender: s.version0.as_ref().map(|q| q.s_typo_descender),
            s_typo_line_gap: s.version0.as_ref().map(|q| q.s_typo_line_gap),
            us_win_ascent: s.version0.as_ref().map(|q| q.us_win_ascent),
            us_win_descent: s.version0.as_ref().map(|q| q.us_win_descent),

            ul_code_page_range1: s.version1.as_ref().map(|q| q.ul_code_page_range1),
            ul_code_page_range2: s.version1.as_ref().map(|q| q.ul_code_page_range2),

            sx_height: s.version2to4.as_ref().map(|q| q.sx_height),
            s_cap_height: s.version2to4.as_ref().map(|q| q.s_cap_height),
            us_default_char: s.version2to4.as_ref().map(|q| q.us_default_char),
            us_break_char: s.version2to4.as_ref().map(|q| q.us_break_char),
            us_max_context: s.version2to4.as_ref().map(|q| q.us_max_context),

            us_lower_optical_point_size: s.version5.as_ref().map(|q| q.us_lower_optical_point_size),
            us_upper_optical_point_size: s.version5.as_ref().map(|q| q.us_upper_optical_point_size),
        },
        _ => Os2Info::default(),
    };

    FontMetrics {
        // head table
        units_per_em: if head_table.units_per_em == 0 {
            1000_u16
        } else {
            head_table.units_per_em
        },
        font_flags: head_table.flags,
        x_min: head_table.x_min,
        y_min: head_table.y_min,
        x_max: head_table.x_max,
        y_max: head_table.y_max,

        // hhea table
        ascender: hhea_table.ascender,
        descender: hhea_table.descender,
        line_gap: hhea_table.line_gap,
        advance_width_max: hhea_table.advance_width_max,
        min_left_side_bearing: hhea_table.min_left_side_bearing,
        min_right_side_bearing: hhea_table.min_right_side_bearing,
        x_max_extent: hhea_table.x_max_extent,
        caret_slope_rise: hhea_table.caret_slope_rise,
        caret_slope_run: hhea_table.caret_slope_run,
        caret_offset: hhea_table.caret_offset,
        num_h_metrics: hhea_table.num_h_metrics,

        // os/2 table
        x_avg_char_width: os2_table.x_avg_char_width,
        us_weight_class: os2_table.us_weight_class,
        us_width_class: os2_table.us_width_class,
        fs_type: os2_table.fs_type,
        y_subscript_x_size: os2_table.y_subscript_x_size,
        y_subscript_y_size: os2_table.y_subscript_y_size,
        y_subscript_x_offset: os2_table.y_subscript_x_offset,
        y_subscript_y_offset: os2_table.y_subscript_y_offset,
        y_superscript_x_size: os2_table.y_superscript_x_size,
        y_superscript_y_size: os2_table.y_superscript_y_size,
        y_superscript_x_offset: os2_table.y_superscript_x_offset,
        y_superscript_y_offset: os2_table.y_superscript_y_offset,
        y_strikeout_size: os2_table.y_strikeout_size,
        y_strikeout_position: os2_table.y_strikeout_position,
        s_family_class: os2_table.s_family_class,
        panose: os2_table.panose,
        ul_unicode_range1: os2_table.ul_unicode_range1,
        ul_unicode_range2: os2_table.ul_unicode_range2,
        ul_unicode_range3: os2_table.ul_unicode_range3,
        ul_unicode_range4: os2_table.ul_unicode_range4,
        ach_vend_id: os2_table.ach_vend_id,
        fs_selection: os2_table.fs_selection,
        us_first_char_index: os2_table.us_first_char_index,
        us_last_char_index: os2_table.us_last_char_index,
        s_typo_ascender: os2_table.s_typo_ascender.into(),
        s_typo_descender: os2_table.s_typo_descender.into(),
        s_typo_line_gap: os2_table.s_typo_line_gap.into(),
        us_win_ascent: os2_table.us_win_ascent.into(),
        us_win_descent: os2_table.us_win_descent.into(),
        ul_code_page_range1: os2_table.ul_code_page_range1.into(),
        ul_code_page_range2: os2_table.ul_code_page_range2.into(),
        sx_height: os2_table.sx_height.into(),
        s_cap_height: os2_table.s_cap_height.into(),
        us_default_char: os2_table.us_default_char.into(),
        us_break_char: os2_table.us_break_char.into(),
        us_max_context: os2_table.us_max_context.into(),
        us_lower_optical_point_size: os2_table.us_lower_optical_point_size.into(),
        us_upper_optical_point_size: os2_table.us_upper_optical_point_size.into(),
    }
}

#[derive(Clone)]
pub struct ParsedFont {
    pub font_metrics: FontMetrics,
    pub num_glyphs: u16,
    pub hhea_table: HheaTable,
    pub hmtx_data: Vec<u8>,
    pub maxp_table: MaxpTable,
    pub gsub_cache: Option<LayoutCache<GSUB>>,
    pub gpos_cache: Option<LayoutCache<GPOS>>,
    pub opt_gdef_table: Option<Rc<GDEFTable>>,
    pub glyph_records_decoded: BTreeMap<u16, OwnedGlyph>,
    pub space_width: Option<usize>,
    pub cmap_subtable: Option<OwnedCmapSubtable>,
}

#[derive(Debug, Clone, PartialEq, PartialOrd)]
#[repr(C, u8)]
pub enum GlyphOutlineOperation {
    MoveTo(OutlineMoveTo),
    LineTo(OutlineLineTo),
    QuadraticCurveTo(OutlineQuadTo),
    CubicCurveTo(OutlineCubicTo),
    ClosePath,
}

#[derive(Debug, Clone, PartialEq, PartialOrd)]
#[repr(C)]
pub struct OutlineMoveTo {
    pub x: f32,
    pub y: f32,
}

#[derive(Debug, Clone, PartialEq, PartialOrd)]
#[repr(C)]
pub struct OutlineLineTo {
    pub x: f32,
    pub y: f32,
}

#[derive(Debug, Clone, PartialEq, PartialOrd)]
#[repr(C)]
pub struct OutlineQuadTo {
    pub ctrl_1_x: f32,
    pub ctrl_1_y: f32,
    pub end_x: f32,
    pub end_y: f32,
}

#[derive(Debug, Clone, PartialEq, PartialOrd)]
#[repr(C)]
pub struct OutlineCubicTo {
    pub ctrl_1_x: f32,
    pub ctrl_1_y: f32,
    pub ctrl_2_x: f32,
    pub ctrl_2_y: f32,
    pub end_x: f32,
    pub end_y: f32,
}

#[derive(Debug, Clone, PartialEq, PartialOrd)]
#[repr(C)]
pub struct GlyphOutline {
    pub operations: GlyphOutlineOperationVec,
}

#[derive(Debug, Clone, PartialEq, PartialOrd)]
struct GlyphOutlineBuilder {
    operations: Vec<GlyphOutlineOperation>,
}

impl Default for GlyphOutlineBuilder {
    fn default() -> Self {
        GlyphOutlineBuilder {
            operations: Vec::new(),
        }
    }
}

impl ttf_parser::OutlineBuilder for GlyphOutlineBuilder {
    fn move_to(&mut self, x: f32, y: f32) {
        self.operations
            .push(GlyphOutlineOperation::MoveTo(OutlineMoveTo { x, y }));
    }
    fn line_to(&mut self, x: f32, y: f32) {
        self.operations
            .push(GlyphOutlineOperation::LineTo(OutlineLineTo { x, y }));
    }
    fn quad_to(&mut self, x1: f32, y1: f32, x: f32, y: f32) {
        self.operations
            .push(GlyphOutlineOperation::QuadraticCurveTo(OutlineQuadTo {
                ctrl_1_x: x1,
                ctrl_1_y: y1,
                end_x: x,
                end_y: y,
            }));
    }
    fn curve_to(&mut self, x1: f32, y1: f32, x2: f32, y2: f32, x: f32, y: f32) {
        self.operations
            .push(GlyphOutlineOperation::CubicCurveTo(OutlineCubicTo {
                ctrl_1_x: x1,
                ctrl_1_y: y1,
                ctrl_2_x: x2,
                ctrl_2_y: y2,
                end_x: x,
                end_y: y,
            }));
    }
    fn close(&mut self) {
        self.operations.push(GlyphOutlineOperation::ClosePath);
    }
}

azul_css::impl_vec!(
    GlyphOutlineOperation,
    GlyphOutlineOperationVec,
    GlyphOutlineOperationVecDestructor
);
azul_css::impl_vec_clone!(
    GlyphOutlineOperation,
    GlyphOutlineOperationVec,
    GlyphOutlineOperationVecDestructor
);
azul_css::impl_vec_debug!(GlyphOutlineOperation, GlyphOutlineOperationVec);
azul_css::impl_vec_partialord!(GlyphOutlineOperation, GlyphOutlineOperationVec);
azul_css::impl_vec_partialeq!(GlyphOutlineOperation, GlyphOutlineOperationVec);

#[derive(Debug, Clone)]
#[repr(C)]
pub struct OwnedGlyphBoundingBox {
    pub max_x: i16,
    pub max_y: i16,
    pub min_x: i16,
    pub min_y: i16,
}

#[derive(Debug, Clone)]
pub struct OwnedGlyph {
    pub bounding_box: OwnedGlyphBoundingBox,
    pub horz_advance: u16,
    pub outline: Option<GlyphOutline>,
}

impl OwnedGlyph {
    fn from_glyph_data<'a>(glyph: Glyph<'a>, horz_advance: u16) -> Option<Self> {
        let bbox = glyph.bounding_box()?;
        Some(Self {
            bounding_box: OwnedGlyphBoundingBox {
                max_x: bbox.x_max,
                max_y: bbox.y_max,
                min_x: bbox.x_min,
                min_y: bbox.y_min,
            },
            horz_advance,
            outline: None,
        })
    }
}

impl ParsedFont {
    pub fn from_bytes(
        font_bytes: &[u8],
        font_index: usize,
        parse_glyph_outlines: bool,
    ) -> Option<Self> {
        use allsorts_subset_browser::tag;

        let scope = ReadScope::new(font_bytes);
        let font_file = scope.read::<FontData<'_>>().ok()?;
        let provider = font_file.table_provider(font_index).ok()?;

        let head_table = provider
            .table_data(tag::HEAD)
            .ok()
            .and_then(|head_data| ReadScope::new(&head_data?).read::<HeadTable>().ok());

        let maxp_table = provider
            .table_data(tag::MAXP)
            .ok()
            .and_then(|maxp_data| ReadScope::new(&maxp_data?).read::<MaxpTable>().ok())
            .unwrap_or(MaxpTable {
                num_glyphs: 0,
                version1_sub_table: None,
            });

        let index_to_loc = head_table
            .map(|s| s.index_to_loc_format)
            .unwrap_or(allsorts_subset_browser::tables::IndexToLocFormat::Long);
        let num_glyphs = maxp_table.num_glyphs as usize;

        let loca_table = provider.table_data(tag::LOCA).ok();
        let loca_table = loca_table
            .as_ref()
            .and_then(|loca_data| {
                ReadScope::new(&loca_data.as_ref()?)
                    .read_dep::<LocaTable<'_>>((num_glyphs, index_to_loc))
                    .ok()
            })
            .unwrap_or(LocaTable {
                offsets: LocaOffsets::Long(
                    allsorts_subset_browser::binary::read::ReadArray::empty(),
                ),
            });

        let glyf_table = provider.table_data(tag::GLYF).ok();
        let mut glyf_table = glyf_table
            .as_ref()
            .and_then(|glyf_data| {
                ReadScope::new(&glyf_data.as_ref()?)
                    .read_dep::<GlyfTable<'_>>(&loca_table)
                    .ok()
            })
            .unwrap_or(GlyfTable::new(Vec::new()).unwrap());

        let hmtx_data = provider
            .table_data(tag::HMTX)
            .ok()
            .and_then(|s| Some(s?.to_vec()))
            .unwrap_or_default();

        let hhea_table = provider
            .table_data(tag::HHEA)
            .ok()
            .and_then(|hhea_data| ReadScope::new(&hhea_data?).read::<HheaTable>().ok())
            .unwrap_or(unsafe { std::mem::zeroed() });

        let font_metrics = get_font_metrics(font_bytes, font_index);

        // not parsing glyph outlines can save lots of memory
        let glyph_records_decoded = glyf_table
            .records_mut()
            .into_iter()
            .enumerate()
            .filter_map(|(glyph_index, glyph_record)| {
                if glyph_index > (u16::MAX as usize) {
                    return None;
                }
                glyph_record.parse().ok()?;
                let glyph_index = glyph_index as u16;
                let horz_advance = allsorts_subset_browser::glyph_info::advance(
                    &maxp_table,
                    &hhea_table,
                    &hmtx_data,
                    glyph_index,
                )
                .unwrap_or_default();

                match glyph_record {
                    GlyfRecord::Present { .. } => None,
                    GlyfRecord::Parsed(g) => OwnedGlyph::from_glyph_data(g.clone(), horz_advance)
                        .map(|g| (glyph_index, g)),
                }
            })
            .collect::<Vec<_>>();

        let glyph_records_decoded = glyph_records_decoded.into_iter().collect();

        let mut font_data_impl = allsorts_subset_browser::font::Font::new(provider).ok()?;

        // required for font layout: gsub_cache, gpos_cache and gdef_table
        let gsub_cache = font_data_impl.gsub_cache().ok().and_then(|s| s);
        let gpos_cache = font_data_impl.gpos_cache().ok().and_then(|s| s);
        let opt_gdef_table = font_data_impl.gdef_table().ok().and_then(|o| o);
        let num_glyphs = font_data_impl.num_glyphs();

        let cmap_subtable = ReadScope::new(font_data_impl.cmap_subtable_data());
        let cmap_subtable = cmap_subtable
            .read::<CmapSubtable<'_>>()
            .ok()
            .and_then(|s| s.to_owned());

        let mut font = ParsedFont {
            font_metrics,
            num_glyphs,
            hhea_table,
            hmtx_data,
            maxp_table,
            gsub_cache,
            gpos_cache,
            opt_gdef_table,
            cmap_subtable,
            glyph_records_decoded,
            space_width: None,
        };

        let space_width = font.get_space_width_internal();
        font.space_width = space_width;

        Some(font)
    }

    fn get_space_width_internal(&mut self) -> Option<usize> {
        let glyph_index = self.lookup_glyph_index(' ' as u32)?;
        allsorts_subset_browser::glyph_info::advance(
            &self.maxp_table,
            &self.hhea_table,
            &self.hmtx_data,
            glyph_index,
        )
        .ok()
        .map(|s| s as usize)
    }

    /// Returns the width of the space " " character
    #[inline]
    pub const fn get_space_width(&self) -> Option<usize> {
        self.space_width
    }

    pub fn get_horizontal_advance(&self, glyph_index: u16) -> u16 {
        self.glyph_records_decoded
            .get(&glyph_index)
            .map(|gi| gi.horz_advance)
            .unwrap_or_default()
    }

    // get the x and y size of a glyph in unscaled units
    pub fn get_glyph_size(&self, glyph_index: u16) -> Option<(i32, i32)> {
        let g = self.glyph_records_decoded.get(&glyph_index)?;
        let glyph_width = g.bounding_box.max_x as i32 - g.bounding_box.min_x as i32; // width
        let glyph_height = g.bounding_box.max_y as i32 - g.bounding_box.min_y as i32; // height
        Some((glyph_width, glyph_height))
    }

    pub fn shape(&self, text: &[u32], script: u32, lang: Option<u32>) -> ShapedTextBufferUnsized {
        shape(self, text, script, lang).unwrap_or_default()
    }

    pub fn lookup_glyph_index(&self, c: u32) -> Option<u16> {
        match self
            .cmap_subtable
            .as_ref()
            .and_then(|s| s.map_glyph(c).ok())
        {
            Some(Some(c)) => Some(c),
            _ => None,
        }
    }
}

#[derive(Debug, PartialEq, Default)]
pub struct ShapedTextBufferUnsized {
    pub infos: Vec<GlyphInfo>,
}

impl ShapedTextBufferUnsized {
    /// Get the word width in unscaled units (respects kerning)
    pub fn get_word_visual_width_unscaled(&self) -> usize {
        self.infos
            .iter()
            .map(|s| s.size.get_x_advance_total_unscaled() as usize)
            .sum()
    }
}

/// Generate a 4-byte font table tag from byte string
///
/// Example:
///
/// ```
/// assert_eq!(tag!(b"glyf"), 0x676C7966);
/// ```
macro_rules! tag {
    ($w:expr) => {
        tag(*$w)
    };
}

const fn tag(chars: [u8; 4]) -> u32 {
    ((chars[3] as u32) << 0)
        | ((chars[2] as u32) << 8)
        | ((chars[1] as u32) << 16)
        | ((chars[0] as u32) << 24)
}

/// Estimate the language and the script from the text (uses trigrams)
#[allow(dead_code)]
pub fn estimate_script_and_language(text: &str) -> (u32, Option<u32>) {
    use crate::text::script::Script; // whatlang::Script

    // https://docs.microsoft.com/en-us/typography/opentype/spec/scripttags

    const TAG_ADLM: u32 = tag!(b"adlm"); // Adlam
    const TAG_AHOM: u32 = tag!(b"ahom"); // Ahom
    const TAG_HLUW: u32 = tag!(b"hluw"); // Anatolian Hieroglyphs
    const TAG_ARAB: u32 = tag!(b"arab"); // Arabic
    const TAG_ARMN: u32 = tag!(b"armn"); // Armenian
    const TAG_AVST: u32 = tag!(b"avst"); // Avestan
    const TAG_BALI: u32 = tag!(b"bali"); // Balinese
    const TAG_BAMU: u32 = tag!(b"bamu"); // Bamum
    const TAG_BASS: u32 = tag!(b"bass"); // Bassa Vah
    const TAG_BATK: u32 = tag!(b"batk"); // Batak
    const TAG_BENG: u32 = tag!(b"beng"); // Bengali
    const TAG_BNG2: u32 = tag!(b"bng2"); // Bengali v.2
    const TAG_BHKS: u32 = tag!(b"bhks"); // Bhaiksuki
    const TAG_BOPO: u32 = tag!(b"bopo"); // Bopomofo
    const TAG_BRAH: u32 = tag!(b"brah"); // Brahmi
    const TAG_BRAI: u32 = tag!(b"brai"); // Braille
    const TAG_BUGI: u32 = tag!(b"bugi"); // Buginese
    const TAG_BUHD: u32 = tag!(b"buhd"); // Buhid
    const TAG_BYZM: u32 = tag!(b"byzm"); // Byzantine Music
    const TAG_CANS: u32 = tag!(b"cans"); // Canadian Syllabics
    const TAG_CARI: u32 = tag!(b"cari"); // Carian
    const TAG_AGHB: u32 = tag!(b"aghb"); // Caucasian Albanian
    const TAG_CAKM: u32 = tag!(b"cakm"); // Chakma
    const TAG_CHAM: u32 = tag!(b"cham"); // Cham
    const TAG_CHER: u32 = tag!(b"cher"); // Cherokee
    const TAG_CHRS: u32 = tag!(b"chrs"); // Chorasmian
    const TAG_HANI: u32 = tag!(b"hani"); // CJK Ideographic
    const TAG_COPT: u32 = tag!(b"copt"); // Coptic
    const TAG_CPRT: u32 = tag!(b"cprt"); // Cypriot Syllabary
    const TAG_CYRL: u32 = tag!(b"cyrl"); // Cyrillic
    const TAG_DFLT: u32 = tag!(b"DFLT"); // Default
    const TAG_DSRT: u32 = tag!(b"dsrt"); // Deseret
    const TAG_DEVA: u32 = tag!(b"deva"); // Devanagari
    const TAG_DEV2: u32 = tag!(b"dev2"); // Devanagari v.2
    const TAG_DIAK: u32 = tag!(b"diak"); // Dives Akuru
    const TAG_DOGR: u32 = tag!(b"dogr"); // Dogra
    const TAG_DUPL: u32 = tag!(b"dupl"); // Duployan
    const TAG_EGYP: u32 = tag!(b"egyp"); // Egyptian Hieroglyphs
    const TAG_ELBA: u32 = tag!(b"elba"); // Elbasan
    const TAG_ELYM: u32 = tag!(b"elym"); // Elymaic
    const TAG_ETHI: u32 = tag!(b"ethi"); // Ethiopic
    const TAG_GEOR: u32 = tag!(b"geor"); // Georgian
    const TAG_GLAG: u32 = tag!(b"glag"); // Glagolitic
    const TAG_GOTH: u32 = tag!(b"goth"); // Gothic
    const TAG_GRAN: u32 = tag!(b"gran"); // Grantha
    const TAG_GREK: u32 = tag!(b"grek"); // Greek
    const TAG_GUJR: u32 = tag!(b"gujr"); // Gujarati
    const TAG_GJR2: u32 = tag!(b"gjr2"); // Gujarati v.2
    const TAG_GONG: u32 = tag!(b"gong"); // Gunjala Gondi
    const TAG_GURU: u32 = tag!(b"guru"); // Gurmukhi
    const TAG_GUR2: u32 = tag!(b"gur2"); // Gurmukhi v.2
    const TAG_HANG: u32 = tag!(b"hang"); // Hangul
    const TAG_JAMO: u32 = tag!(b"jamo"); // Hangul Jamo
    const TAG_ROHG: u32 = tag!(b"rohg"); // Hanifi Rohingya
    const TAG_HANO: u32 = tag!(b"hano"); // Hanunoo
    const TAG_HATR: u32 = tag!(b"hatr"); // Hatran
    const TAG_HEBR: u32 = tag!(b"hebr"); // Hebrew
    const TAG_HIRG: u32 = tag!(b"kana"); // Hiragana
    const TAG_ARMI: u32 = tag!(b"armi"); // Imperial Aramaic
    const TAG_PHLI: u32 = tag!(b"phli"); // Inscriptional Pahlavi
    const TAG_PRTI: u32 = tag!(b"prti"); // Inscriptional Parthian
    const TAG_JAVA: u32 = tag!(b"java"); // Javanese
    const TAG_KTHI: u32 = tag!(b"kthi"); // Kaithi
    const TAG_KNDA: u32 = tag!(b"knda"); // Kannada
    const TAG_KND2: u32 = tag!(b"knd2"); // Kannada v.2
    const TAG_KANA: u32 = tag!(b"kana"); // Katakana
    const TAG_KALI: u32 = tag!(b"kali"); // Kayah Li
    const TAG_KHAR: u32 = tag!(b"khar"); // Kharosthi
    const TAG_KITS: u32 = tag!(b"kits"); // Khitan Small Script
    const TAG_KHMR: u32 = tag!(b"khmr"); // Khmer
    const TAG_KHOJ: u32 = tag!(b"khoj"); // Khojki
    const TAG_SIND: u32 = tag!(b"sind"); // Khudawadi
    const TAG_LAO: u32 = tag!(b"lao "); // Lao
    const TAG_LATN: u32 = tag!(b"latn"); // Latin
    const TAG_LEPC: u32 = tag!(b"lepc"); // Lepcha
    const TAG_LIMB: u32 = tag!(b"limb"); // Limbu
    const TAG_LINA: u32 = tag!(b"lina"); // Linear A
    const TAG_LINB: u32 = tag!(b"linb"); // Linear B
    const TAG_LISU: u32 = tag!(b"lisu"); // Lisu (Fraser)
    const TAG_LYCI: u32 = tag!(b"lyci"); // Lycian
    const TAG_LYDI: u32 = tag!(b"lydi"); // Lydian
    const TAG_MAHJ: u32 = tag!(b"mahj"); // Mahajani
    const TAG_MAKA: u32 = tag!(b"maka"); // Makasar
    const TAG_MLYM: u32 = tag!(b"mlym"); // Malayalam
    const TAG_MLM2: u32 = tag!(b"mlm2"); // Malayalam v.2
    const TAG_MAND: u32 = tag!(b"mand"); // Mandaic, Mandaean
    const TAG_MANI: u32 = tag!(b"mani"); // Manichaean
    const TAG_MARC: u32 = tag!(b"marc"); // Marchen
    const TAG_GONM: u32 = tag!(b"gonm"); // Masaram Gondi
    const TAG_MATH: u32 = tag!(b"math"); // Mathematical Alphanumeric Symbols
    const TAG_MEDF: u32 = tag!(b"medf"); // Medefaidrin (Oberi Okaime, Oberi kaim)
    const TAG_MTEI: u32 = tag!(b"mtei"); // Meitei Mayek (Meithei, Meetei)
    const TAG_MEND: u32 = tag!(b"mend"); // Mende Kikakui
    const TAG_MERC: u32 = tag!(b"merc"); // Meroitic Cursive
    const TAG_MERO: u32 = tag!(b"mero"); // Meroitic Hieroglyphs
    const TAG_PLRD: u32 = tag!(b"plrd"); // Miao
    const TAG_MODI: u32 = tag!(b"modi"); // Modi
    const TAG_MONG: u32 = tag!(b"mong"); // Mongolian
    const TAG_MROO: u32 = tag!(b"mroo"); // Mro
    const TAG_MULT: u32 = tag!(b"mult"); // Multani
    const TAG_MUSC: u32 = tag!(b"musc"); // Musical Symbols
    const TAG_MYMR: u32 = tag!(b"mymr"); // Myanmar
    const TAG_MYM2: u32 = tag!(b"mym2"); // Myanmar v.2
    const TAG_NBAT: u32 = tag!(b"nbat"); // Nabataean
    const TAG_NAND: u32 = tag!(b"nand"); // Nandinagari
    const TAG_NEWA: u32 = tag!(b"newa"); // Newa
    const TAG_TALU: u32 = tag!(b"talu"); // New Tai Lue
    const TAG_NKO: u32 = tag!(b"nko "); // N'Ko
    const TAG_NSHU: u32 = tag!(b"nshu"); // Nüshu
    const TAG_HMNP: u32 = tag!(b"hmnp"); // Nyiakeng Puachue Hmong
    const TAG_ORYA: u32 = tag!(b"orya"); // Odia (formerly Oriya)
    const TAG_ORY2: u32 = tag!(b"ory2"); // Odia v.2 (formerly Oriya v.2)
    const TAG_OGAM: u32 = tag!(b"ogam"); // Ogham
    const TAG_OLCK: u32 = tag!(b"olck"); // Ol Chiki
    const TAG_ITAL: u32 = tag!(b"ital"); // Old Italic
    const TAG_HUNG: u32 = tag!(b"hung"); // Old Hungarian
    const TAG_NARB: u32 = tag!(b"narb"); // Old North Arabian
    const TAG_PERM: u32 = tag!(b"perm"); // Old Permic
    const TAG_XPEO: u32 = tag!(b"xpeo"); // Old Persian Cuneiform
    const TAG_SOGO: u32 = tag!(b"sogo"); // Old Sogdian
    const TAG_SARB: u32 = tag!(b"sarb"); // Old South Arabian
    const TAG_ORKH: u32 = tag!(b"orkh"); // Old Turkic, Orkhon Runic
    const TAG_OSGE: u32 = tag!(b"osge"); // Osage
    const TAG_OSMA: u32 = tag!(b"osma"); // Osmanya
    const TAG_HMNG: u32 = tag!(b"hmng"); // Pahawh Hmong
    const TAG_PALM: u32 = tag!(b"palm"); // Palmyrene
    const TAG_PAUC: u32 = tag!(b"pauc"); // Pau Cin Hau
    const TAG_PHAG: u32 = tag!(b"phag"); // Phags-pa
    const TAG_PHNX: u32 = tag!(b"phnx"); // Phoenician
    const TAG_PHLP: u32 = tag!(b"phlp"); // Psalter Pahlavi
    const TAG_RJNG: u32 = tag!(b"rjng"); // Rejang
    const TAG_RUNR: u32 = tag!(b"runr"); // Runic
    const TAG_SAMR: u32 = tag!(b"samr"); // Samaritan
    const TAG_SAUR: u32 = tag!(b"saur"); // Saurashtra
    const TAG_SHRD: u32 = tag!(b"shrd"); // Sharada
    const TAG_SHAW: u32 = tag!(b"shaw"); // Shavian
    const TAG_SIDD: u32 = tag!(b"sidd"); // Siddham
    const TAG_SGNW: u32 = tag!(b"sgnw"); // Sign Writing
    const TAG_SINH: u32 = tag!(b"sinh"); // Sinhala
    const TAG_SOGD: u32 = tag!(b"sogd"); // Sogdian
    const TAG_SORA: u32 = tag!(b"sora"); // Sora Sompeng
    const TAG_SOYO: u32 = tag!(b"soyo"); // Soyombo
    const TAG_XSUX: u32 = tag!(b"xsux"); // Sumero-Akkadian Cuneiform
    const TAG_SUND: u32 = tag!(b"sund"); // Sundanese
    const TAG_SYLO: u32 = tag!(b"sylo"); // Syloti Nagri
    const TAG_SYRC: u32 = tag!(b"syrc"); // Syriac
    const TAG_TGLG: u32 = tag!(b"tglg"); // Tagalog
    const TAG_TAGB: u32 = tag!(b"tagb"); // Tagbanwa
    const TAG_TALE: u32 = tag!(b"tale"); // Tai Le
    const TAG_LANA: u32 = tag!(b"lana"); // Tai Tham (Lanna)
    const TAG_TAVT: u32 = tag!(b"tavt"); // Tai Viet
    const TAG_TAKR: u32 = tag!(b"takr"); // Takri
    const TAG_TAML: u32 = tag!(b"taml"); // Tamil
    const TAG_TML2: u32 = tag!(b"tml2"); // Tamil v.2
    const TAG_TANG: u32 = tag!(b"tang"); // Tangut
    const TAG_TELU: u32 = tag!(b"telu"); // Telugu
    const TAG_TEL2: u32 = tag!(b"tel2"); // Telugu v.2
    const TAG_THAA: u32 = tag!(b"thaa"); // Thaana
    const TAG_THAI: u32 = tag!(b"thai"); // Thai
    const TAG_TIBT: u32 = tag!(b"tibt"); // Tibetan
    const TAG_TFNG: u32 = tag!(b"tfng"); // Tifinagh
    const TAG_TIRH: u32 = tag!(b"tirh"); // Tirhuta
    const TAG_UGAR: u32 = tag!(b"ugar"); // Ugaritic Cuneiform
    const TAG_VAI: u32 = tag!(b"vai "); // Vai
    const TAG_WCHO: u32 = tag!(b"wcho"); // Wancho
    const TAG_WARA: u32 = tag!(b"wara"); // Warang Citi
    const TAG_YEZI: u32 = tag!(b"yezi"); // Yezidi
    const TAG_ZANB: u32 = tag!(b"zanb"); // Zanabazar Square
                                         // missing: Yi

    // auto-detect script + language from text (todo: performance!)

    // let (lang, script) = whatlang::detect(text)
    //     .map(|info| (info.lang(), info.script()))
    //     .unwrap_or((Lang::Eng, Script::Latin));

    let lang = None; // detecting the language is only necessary for special font features

    // let lang = tag_mod::from_string(&lang.code().to_string().to_uppercase()).unwrap();

    let script = match crate::text::script::detect_script(text).unwrap_or(Script::Latin) {
        Script::Arabic => TAG_ARAB,
        Script::Bengali => TAG_BENG,
        Script::Cyrillic => TAG_CYRL,
        Script::Devanagari => TAG_DEVA,
        Script::Ethiopic => TAG_ETHI,
        Script::Georgian => TAG_GEOR,
        Script::Greek => TAG_GREK,
        Script::Gujarati => TAG_GUJR,
        Script::Gurmukhi => TAG_GUR2,
        Script::Hangul => TAG_HANG,
        Script::Hebrew => TAG_HEBR,
        Script::Hiragana => TAG_HIRG, // NOTE: tag = 'kana', probably error
        Script::Kannada => TAG_KND2,
        Script::Katakana => TAG_KANA,
        Script::Khmer => TAG_KHMR,
        Script::Latin => TAG_LATN,
        Script::Malayalam => TAG_MLYM,
        Script::Mandarin => TAG_MAND,
        Script::Myanmar => TAG_MYM2,
        Script::Oriya => TAG_ORYA,
        Script::Sinhala => TAG_SINH,
        Script::Tamil => TAG_TAML,
        Script::Telugu => TAG_TELU,
        Script::Thai => TAG_THAI,
    };

    (script, lang)
}

// shape_word(text: &str, &font) -> TextBuffer
// get_word_visual_width(word: &TextBuffer) ->
// get_glyph_instances(infos: &GlyphInfos, positions: &GlyphPositions) -> PositionedGlyphBuffer

fn shape<'a>(
    font: &ParsedFont,
    text: &[u32],
    script: u32,
    lang: Option<u32>,
) -> Option<ShapedTextBufferUnsized> {
    use core::convert::TryFrom;

    use allsorts_subset_browser::{
        gpos::apply as gpos_apply,
        gsub::{apply as gsub_apply, FeatureMask, Features},
    };

    // Map glyphs
    //
    // We look ahead in the char stream for variation selectors. If one is found it is used for
    // mapping the current glyph. When a variation selector is reached in the stream it is skipped
    // as it was handled as part of the preceding character.
    let mut chars_iter = text.iter().peekable();
    let mut glyphs = Vec::with_capacity(text.len());

    while let Some((ch, ch_as_char)) = chars_iter
        .next()
        .and_then(|c| Some((c, core::char::from_u32(*c)?)))
    {
        match allsorts_subset_browser::unicode::VariationSelector::try_from(ch_as_char) {
            Ok(_) => {} // filter out variation selectors
            Err(()) => {
                let vs = chars_iter.peek().and_then(|&next| {
                    allsorts_subset_browser::unicode::VariationSelector::try_from(
                        core::char::from_u32(*next)?,
                    )
                    .ok()
                });

                let glyph_index = font.lookup_glyph_index(*ch).unwrap_or(0);
                glyphs.push(make_raw_glyph(ch_as_char, glyph_index, vs));
            }
        }
    }

    const DOTTED_CIRCLE: u32 = '\u{25cc}' as u32;
    let dotted_circle_index = font.lookup_glyph_index(DOTTED_CIRCLE).unwrap_or(0);

    // Apply glyph substitution if table is present
    if let Some(gsub) = &font.gsub_cache {
        gsub_apply(
            dotted_circle_index,
            gsub,
            font.opt_gdef_table.as_ref().map(|f| Rc::as_ref(f)),
            script,
            lang,
            &Features::Mask(FeatureMask::empty()),
            None, // TODO: variable fonts?
            font.num_glyphs,
            &mut glyphs,
        )
        .ok()?;
    }

    // Apply glyph positioning if table is present

    let kerning = true;
    let mut infos = allsorts_subset_browser::gpos::Info::init_from_glyphs(
        font.opt_gdef_table.as_ref().map(|f| Rc::as_ref(f)),
        glyphs,
    );

    if let Some(gpos) = &font.gpos_cache {
        gpos_apply(
            gpos,
            font.opt_gdef_table.as_ref().map(|f| Rc::as_ref(f)),
            kerning,
            &Features::Mask(FeatureMask::all()),
            None, // TODO: variable fonts?
            script,
            lang,
            &mut infos,
        )
        .ok()?;
    }

    // calculate the horizontal advance for each char
    let infos = infos
        .iter()
        .filter_map(|info| {
            let glyph_index = info.glyph.glyph_index;
            let adv_x = font.get_horizontal_advance(glyph_index);
            let (size_x, size_y) = font.get_glyph_size(glyph_index)?;
            let advance = Advance {
                advance_x: adv_x,
                size_x,
                size_y,
                kerning: info.kerning,
            };
            let info = translate_info(&info, advance);
            Some(info)
        })
        .collect();

    Some(ShapedTextBufferUnsized { infos })
}

#[inline]
fn translate_info(i: &allsorts_subset_browser::gpos::Info, size: Advance) -> GlyphInfo {
    GlyphInfo {
        glyph: translate_raw_glyph(&i.glyph),
        size,
        kerning: i.kerning,
        placement: translate_placement(&i.placement),
    }
}

fn make_raw_glyph(
    ch: char,
    glyph_index: u16,
    variation: Option<allsorts_subset_browser::unicode::VariationSelector>,
) -> allsorts_subset_browser::gsub::RawGlyph<()> {
    allsorts_subset_browser::gsub::RawGlyph {
        unicodes: tiny_vec![[char; 1] => ch],
        glyph_index,
        liga_component_pos: 0,
        glyph_origin: allsorts_subset_browser::gsub::GlyphOrigin::Char(ch),
        flags: RawGlyphFlags::empty(),
        extra_data: (),
        variation,
    }
}

#[inline]
fn translate_raw_glyph(rg: &allsorts_subset_browser::gsub::RawGlyph<()>) -> RawGlyph {
    RawGlyph {
        unicode_codepoint: rg.unicodes.get(0).map(|s| (*s) as u32).into(),
        glyph_index: rg.glyph_index,
        liga_component_pos: rg.liga_component_pos,
        glyph_origin: translate_glyph_origin(&rg.glyph_origin),
        small_caps: rg.small_caps(),
        multi_subst_dup: rg.multi_subst_dup(),
        is_vert_alt: rg.is_vert_alt(),
        fake_bold: rg.fake_bold(),
        fake_italic: rg.fake_italic(),
        variation: rg
            .variation
            .as_ref()
            .map(translate_variation_selector)
            .into(),
    }
}

#[inline]
const fn translate_glyph_origin(g: &allsorts_subset_browser::gsub::GlyphOrigin) -> GlyphOrigin {
    use allsorts_subset_browser::gsub::GlyphOrigin::*;
    match g {
        Char(c) => GlyphOrigin::Char(*c),
        Direct => GlyphOrigin::Direct,
    }
}

#[inline]
const fn translate_placement(p: &allsorts_subset_browser::gpos::Placement) -> Placement {
    use allsorts_subset_browser::gpos::Placement::*;
    use azul_core::app_resources::{
        CursiveAnchorPlacement, MarkAnchorPlacement, PlacementDistance,
    };

    match p {
        None => Placement::None,
        Distance(x, y) => Placement::Distance(PlacementDistance { x: *x, y: *y }),
        MarkAnchor(i, a1, a2) => Placement::MarkAnchor(MarkAnchorPlacement {
            base_glyph_index: *i,
            base_glyph_anchor: translate_anchor(a1),
            mark_anchor: translate_anchor(a2),
        }),
        MarkOverprint(i) => Placement::MarkOverprint(*i),
        CursiveAnchor(i, b, a1, a2) => Placement::CursiveAnchor(CursiveAnchorPlacement {
            exit_glyph_index: *i,
            right_to_left: *b,
            exit_glyph_anchor: translate_anchor(a1),
            entry_glyph_anchor: translate_anchor(a2),
        }),
    }
}

const fn translate_variation_selector(
    v: &allsorts_subset_browser::unicode::VariationSelector,
) -> VariationSelector {
    use allsorts_subset_browser::unicode::VariationSelector::*;
    match v {
        VS01 => VariationSelector::VS01,
        VS02 => VariationSelector::VS02,
        VS03 => VariationSelector::VS03,
        VS15 => VariationSelector::VS15,
        VS16 => VariationSelector::VS16,
    }
}

#[inline]
const fn translate_anchor(anchor: &allsorts_subset_browser::layout::Anchor) -> Anchor {
    Anchor {
        x: anchor.x,
        y: anchor.y,
    }
}