use super::*;

/// Writer for a _Type-1 font dictionary_.
///
/// This struct is created by [`PdfWriter::type1_font`].
pub struct Type1Font<'a> {
    dict: Dict<'a>,
}

impl<'a> Writer<'a> for Type1Font<'a> {
    fn start(obj: Obj<'a>) -> Self {
        let mut dict = obj.dict();
        dict.pair(Name(b"Type"), Name(b"Font"));
        dict.pair(Name(b"Subtype"), Name(b"Type1"));
        Self { dict }
    }
}

impl<'a> Type1Font<'a> {
    /// Write the `/Name` attribute, which is the name of the font in the
    /// current resource dictionary. Required in PDF 1.0, discouraged in PDF
    /// 1.1+.
    pub fn name(&mut self, name: Name) -> &mut Self {
        self.pair(Name(b"Name"), name);
        self
    }

    /// Write the `/BaseFont` attribute. This is the PostScript name of the
    /// font. Required.
    pub fn base_font(&mut self, name: Name) -> &mut Self {
        self.pair(Name(b"BaseFont"), name);
        self
    }

    /// Write the `FirstChar` attribute, defining the first character code in
    /// the font's widths array. Required (except for standard 14 fonts
    /// before PDF 1.5).
    pub fn first_char(&mut self, first: u8) -> &mut Self {
        self.pair(Name(b"FirstChar"), i32::from(first));
        self
    }

    /// Write the `LastChar` attribute, defining the last character code in the
    /// font's widths array. Required (except for standard 14 fonts before
    /// PDF 1.5).
    pub fn last_char(&mut self, last: u8) -> &mut Self {
        self.pair(Name(b"LastChar"), i32::from(last));
        self
    }

    /// Write the `/Widths` array. Should be of length `last - first + 1`.
    /// Required (except for standard 14 fonts before PDF 1.5).
    pub fn widths(&mut self, widths: impl IntoIterator<Item = f32>) -> &mut Self {
        self.insert(Name(b"Widths")).array().items(widths);
        self
    }

    /// Write the `/FontDescriptor` attribute. Required (except for standard 14
    /// fonts before PDF 1.5).
    pub fn font_descriptor(&mut self, id: Ref) -> &mut Self {
        self.pair(Name(b"FontDescriptor"), id);
        self
    }

    /// Write the `/Encoding` attribute as a predefined encoding. Either this or
    /// [`encoding_custom`](Self::encoding_custom) is required.
    pub fn encoding_predefined(&mut self, encoding: Name) -> &mut Self {
        self.pair(Name(b"Encoding"), encoding);
        self
    }

    /// Start writing an `/Encoding` dictionary. Either this or
    /// [`encoding_predefined`](Self::encoding_predefined) is required.
    pub fn encoding_custom(&mut self) -> Encoding<'_> {
        self.insert(Name(b"Encoding")).start()
    }

    /// Write the `/ToUnicode` attribute. PDF 1.2+.
    ///
    /// A suitable character map can be built with [`UnicodeCmap`].
    pub fn to_unicode(&mut self, id: Ref) -> &mut Self {
        self.pair(Name(b"ToUnicode"), id);
        self
    }
}

deref!('a, Type1Font<'a> => Dict<'a>, dict);

/// Writer for a _Type-3 font dictionary_.
///
/// This struct is created by [`PdfWriter::type3_font`].
pub struct Type3Font<'a> {
    dict: Dict<'a>,
}

impl<'a> Writer<'a> for Type3Font<'a> {
    fn start(obj: Obj<'a>) -> Self {
        let mut dict = obj.dict();
        dict.pair(Name(b"Type"), Name(b"Font"));
        dict.pair(Name(b"Subtype"), Name(b"Type3"));
        Self { dict }
    }
}

impl<'a> Type3Font<'a> {
    /// Write the `/Name` attribute, which is the name of the font in the
    /// current resource dictionary. Required in PDF 1.0, discouraged in PDF
    /// 1.1+.
    pub fn name(&mut self, name: Name) -> &mut Self {
        self.pair(Name(b"Name"), name);
        self
    }

    /// Write the `/FontBBox` attribute. Required.
    pub fn bbox(&mut self, bbox: Rect) -> &mut Self {
        self.pair(Name(b"FontBBox"), bbox);
        self
    }

    /// Write the `/FontMatrix` attribute, which defines the mapping from glyph
    /// space to text space. Required.
    pub fn matrix(&mut self, matrix: [f32; 6]) -> &mut Self {
        self.insert(Name(b"FontMatrix")).array().items(matrix);
        self
    }

    /// Write the `/CharProcs` dictionary, which maps glyph names to glyph
    /// content streams. Required.
    ///
    /// Each glyph's content stream must start with either the
    /// [`d0`](crate::Content::start_color_glyph) or
    /// [`d1`](crate::Content::start_shape_glyph) operator.
    pub fn char_procs(&mut self) -> TypedDict<'_, Ref> {
        self.insert(Name(b"CharProcs")).dict().typed()
    }

    /// Write the `/Encoding` attribute as a predefined encoding. Either this or
    /// [`encoding_custom`](Self::encoding_custom) is required.
    pub fn encoding_predefined(&mut self, encoding: Name) -> &mut Self {
        self.pair(Name(b"Encoding"), encoding);
        self
    }

    /// Start writing an `/Encoding` dictionary. Either this or
    /// [`encoding_predefined`](Self::encoding_predefined) is required.
    pub fn encoding_custom(&mut self) -> Encoding<'_> {
        self.insert(Name(b"Encoding")).start()
    }

    /// Write the `FirstChar` attribute, defining the first character code in
    /// the font's widths array. Required.
    pub fn first_char(&mut self, first: u8) -> &mut Self {
        self.pair(Name(b"FirstChar"), i32::from(first));
        self
    }

    /// Write the `LastChar` attribute, defining the last character code in the
    /// font's widths array. Required.
    pub fn last_char(&mut self, last: u8) -> &mut Self {
        self.pair(Name(b"LastChar"), i32::from(last));
        self
    }

    /// Write the `/Widths` array. Should be of length `last - first + 1`.
    /// Required.
    pub fn widths(&mut self, widths: impl IntoIterator<Item = f32>) -> &mut Self {
        self.insert(Name(b"Widths")).array().items(widths);
        self
    }

    /// Write the `/FontDescriptor` attribute. Required in Tagged PDFs.
    pub fn font_descriptor(&mut self, id: Ref) -> &mut Self {
        self.pair(Name(b"FontDescriptor"), id);
        self
    }

    /// Start writing the `/Resources` dictionary.
    pub fn resources(&mut self) -> Resources<'_> {
        self.insert(Name(b"Resources")).start()
    }

    /// Write the `/ToUnicode` attribute. PDF 1.2+.
    ///
    /// A suitable character map can be built with [`UnicodeCmap`].
    pub fn to_unicode(&mut self, id: Ref) -> &mut Self {
        self.pair(Name(b"ToUnicode"), id);
        self
    }
}

deref!('a, Type3Font<'a> => Dict<'a>, dict);

/// Writer for a _simple font encoding dictionary_.
///
/// This struct is created by [`Type1Font::encoding_custom`] and
/// [`Type3Font::encoding_custom`].
pub struct Encoding<'a> {
    dict: Dict<'a>,
}

impl<'a> Writer<'a> for Encoding<'a> {
    fn start(obj: Obj<'a>) -> Self {
        let mut dict = obj.dict();
        dict.pair(Name(b"Type"), Name(b"Encoding"));
        Self { dict }
    }
}

impl<'a> Encoding<'a> {
    /// Write the `BaseEncoding` attribute, from which this encoding is
    /// described through differences.
    pub fn base_encoding(&mut self, name: Name) -> &mut Self {
        self.pair(Name(b"BaseEncoding"), name);
        self
    }

    /// Start writing the `/Differences` array.
    pub fn differences(&mut self) -> Differences<'_> {
        self.insert(Name(b"Differences")).start()
    }
}

deref!('a, Encoding<'a> => Dict<'a>, dict);

/// Writer for an _encoding differences array_.
///
/// This struct is created by [`Encoding::differences`].
pub struct Differences<'a> {
    array: Array<'a>,
}

impl<'a> Writer<'a> for Differences<'a> {
    fn start(obj: Obj<'a>) -> Self {
        Self { array: obj.array() }
    }
}

impl<'a> Differences<'a> {
    /// Maps consecutive character codes starting at `start` to the given glyph
    /// names.
    pub fn consecutive<'n>(
        &mut self,
        start: u8,
        names: impl IntoIterator<Item = Name<'n>>,
    ) -> &mut Self {
        self.item(i32::from(start));
        for name in names {
            self.item(name);
        }
        self
    }
}

deref!('a, Differences<'a> => Array<'a>, array);

/// Writer for a _Type-0 (composite) font dictionary_. PDF 1.2+.
///
/// This struct is created by [`PdfWriter::type0_font`].
pub struct Type0Font<'a> {
    dict: Dict<'a>,
}

impl<'a> Writer<'a> for Type0Font<'a> {
    fn start(obj: Obj<'a>) -> Self {
        let mut dict = obj.dict();
        dict.pair(Name(b"Type"), Name(b"Font"));
        dict.pair(Name(b"Subtype"), Name(b"Type0"));
        Self { dict }
    }
}

impl<'a> Type0Font<'a> {
    /// Write the `/BaseFont` attribute. This is the PostScript name of the
    /// font. Required.
    pub fn base_font(&mut self, name: Name) -> &mut Self {
        self.pair(Name(b"BaseFont"), name);
        self
    }

    /// Write the `/Encoding` attribute as a predefined encoding. Either this or
    /// [`encoding_cmap`](Self::encoding_cmap) is required.
    pub fn encoding_predefined(&mut self, encoding: Name) -> &mut Self {
        self.pair(Name(b"Encoding"), encoding);
        self
    }

    /// Write the `/Encoding` attribute as a reference to a character map.
    /// Either this or [`encoding_predefined`](Self::encoding_predefined) is
    /// required.
    pub fn encoding_cmap(&mut self, cmap: Ref) -> &mut Self {
        self.pair(Name(b"Encoding"), cmap);
        self
    }

    /// Write the `/DescendantFonts` attribute as a one-element array containing
    /// a reference to a [`CidFont`]. Required.
    pub fn descendant_font(&mut self, cid_font: Ref) -> &mut Self {
        self.insert(Name(b"DescendantFonts")).array().item(cid_font);
        self
    }

    /// Write the `/ToUnicode` attribute.
    ///
    /// A suitable character map can be built with [`UnicodeCmap`].
    pub fn to_unicode(&mut self, cmap: Ref) -> &mut Self {
        self.pair(Name(b"ToUnicode"), cmap);
        self
    }
}

deref!('a, Type0Font<'a> => Dict<'a>, dict);

/// Writer for a _CID font dictionary_. PDF 1.2+.
///
/// This struct is created by [`PdfWriter::cid_font`].
pub struct CidFont<'a> {
    dict: Dict<'a>,
}

impl<'a> Writer<'a> for CidFont<'a> {
    fn start(obj: Obj<'a>) -> Self {
        let mut dict = obj.dict();
        dict.pair(Name(b"Type"), Name(b"Font"));
        Self { dict }
    }
}

impl<'a> CidFont<'a> {
    /// Write the `/Subtype` attribute. Required.
    pub fn subtype(&mut self, subtype: CidFontType) -> &mut Self {
        self.pair(Name(b"Subtype"), subtype.to_name());
        self
    }

    /// Write the `/BaseFont` attribute. Required.
    pub fn base_font(&mut self, name: Name) -> &mut Self {
        self.pair(Name(b"BaseFont"), name);
        self
    }

    /// Write the `/CIDSystemInfo` dictionary. Required.
    pub fn system_info(&mut self, info: SystemInfo) -> &mut Self {
        info.write(self.insert(Name(b"CIDSystemInfo")));
        self
    }

    /// Write the `/FontDescriptor` attribute. Required.
    pub fn font_descriptor(&mut self, id: Ref) -> &mut Self {
        self.pair(Name(b"FontDescriptor"), id);
        self
    }

    /// Write the `/DW` attribute, specifying the default glyph width.
    pub fn default_width(&mut self, width: f32) -> &mut Self {
        self.pair(Name(b"DW"), width);
        self
    }

    /// Start writing the `/W` (widths) array.
    pub fn widths(&mut self) -> Widths<'_> {
        self.insert(Name(b"W")).start()
    }

    /// Write the `/CIDToGIDMap` attribute as a predefined name.
    pub fn cid_to_gid_map_predefined(&mut self, name: Name) -> &mut Self {
        self.pair(Name(b"CIDToGIDMap"), name);
        self
    }

    /// Write the `/CIDToGIDMap` attribute as a reference to a stream, whose
    /// bytes directly map from CIDs to glyph indices.
    pub fn cid_to_gid_map_stream(&mut self, stream: Ref) -> &mut Self {
        self.pair(Name(b"CIDToGIDMap"), stream);
        self
    }
}

deref!('a, CidFont<'a> => Dict<'a>, dict);

/// The subtype of a CID font.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub enum CidFontType {
    /// A CID font containing CFF glyph descriptions.
    Type0,
    /// A CID font containing TrueType glyph descriptions.
    Type2,
}

impl CidFontType {
    pub(crate) fn to_name(self) -> Name<'static> {
        match self {
            Self::Type0 => Name(b"CIDFontType0"),
            Self::Type2 => Name(b"CIDFontType2"),
        }
    }
}

/// Writer for a _CID font widths array_.
///
/// This struct is created by [`CidFont::widths`].
pub struct Widths<'a> {
    array: Array<'a>,
}

impl<'a> Writer<'a> for Widths<'a> {
    fn start(obj: Obj<'a>) -> Self {
        Self { array: obj.array() }
    }
}

impl<'a> Widths<'a> {
    /// Specifies individual widths for a range of consecutive CIDs starting at
    /// `start`.
    pub fn consecutive(
        &mut self,
        start: u16,
        widths: impl IntoIterator<Item = f32>,
    ) -> &mut Self {
        self.item(i32::from(start));
        self.push().array().items(widths);
        self
    }

    /// Specifies the same width for all CIDs between `first` and `last`.
    pub fn same(&mut self, first: u16, last: u16, width: f32) -> &mut Self {
        self.item(i32::from(first));
        self.item(i32::from(last));
        self.item(width);
        self
    }
}

deref!('a, Widths<'a> => Array<'a>, array);

/// Writer for a _font descriptor dictionary_.
///
/// This struct is created by [`PdfWriter::font_descriptor`].
pub struct FontDescriptor<'a> {
    dict: Dict<'a>,
}

impl<'a> Writer<'a> for FontDescriptor<'a> {
    fn start(obj: Obj<'a>) -> Self {
        let mut dict = obj.dict();
        dict.pair(Name(b"Type"), Name(b"FontDescriptor"));
        Self { dict }
    }
}

impl<'a> FontDescriptor<'a> {
    /// Write the `/FontName` attribute. Required.
    pub fn name(&mut self, name: Name) -> &mut Self {
        self.pair(Name(b"FontName"), name);
        self
    }

    /// Write the `/FontFamily` attribute. Recommended for Type 3 fonts in
    /// Tagged PDFs. PDF 1.5+.
    pub fn family(&mut self, family: Str) -> &mut Self {
        self.pair(Name(b"FontFamily"), family);
        self
    }

    /// Write the `/FontStretch` attribute. Recommended for Type 3 fonts in
    /// Tagged PDFs. PDF 1.5+.
    pub fn stretch(&mut self, stretch: FontStretch) -> &mut Self {
        self.pair(Name(b"FontStretch"), stretch.to_name());
        self
    }

    /// Write the `/FontWeight` attribute. Should be between 100 (lightest) and
    /// 900 (heaviest), 400 is normal weight, 700 is bold. Recommended
    /// for Type 3 fonts in Tagged PDFs. PDF 1.5+.
    pub fn weight(&mut self, weight: u16) -> &mut Self {
        self.pair(Name(b"FontWeight"), i32::from(weight));
        self
    }

    /// Write the `/Flags` attribute. Required.
    pub fn flags(&mut self, flags: FontFlags) -> &mut Self {
        self.pair(Name(b"Flags"), flags.bits() as i32);
        self
    }

    /// Write the `/FontBBox` attribute. Required, except for Type 3 fonts.
    pub fn bbox(&mut self, bbox: Rect) -> &mut Self {
        self.pair(Name(b"FontBBox"), bbox);
        self
    }

    /// Write the `/ItalicAngle` attribute. Required.
    pub fn italic_angle(&mut self, angle: f32) -> &mut Self {
        self.pair(Name(b"ItalicAngle"), angle);
        self
    }

    /// Write the `/Ascent` attribute. Required.
    pub fn ascent(&mut self, ascent: f32) -> &mut Self {
        self.pair(Name(b"Ascent"), ascent);
        self
    }

    /// Write the `/Descent` attribute. Required.
    pub fn descent(&mut self, descent: f32) -> &mut Self {
        self.pair(Name(b"Descent"), descent);
        self
    }

    /// Write the `/Leading` attribute.
    pub fn leading(&mut self, leading: f32) -> &mut Self {
        self.pair(Name(b"Leading"), leading);
        self
    }

    /// Write the `/CapHeight` attribute. Required for fonts with Latin
    /// characters, except for Type 3 fonts.
    pub fn cap_height(&mut self, cap_height: f32) -> &mut Self {
        self.pair(Name(b"CapHeight"), cap_height);
        self
    }

    /// Write the `/XHeight` attribute.
    pub fn x_height(&mut self, x_height: f32) -> &mut Self {
        self.pair(Name(b"XHeight"), x_height);
        self
    }

    /// Write the `/StemV` attribute. Required, except for Type 3 fonts.
    pub fn stem_v(&mut self, stem_v: f32) -> &mut Self {
        self.pair(Name(b"StemV"), stem_v);
        self
    }

    /// Write the `/StemH` attribute.
    pub fn stem_h(&mut self, stem_h: f32) -> &mut Self {
        self.pair(Name(b"StemH"), stem_h);
        self
    }

    /// Write the `/AvgWidth` attribute.
    pub fn avg_width(&mut self, avg_width: f32) -> &mut Self {
        self.pair(Name(b"AvgWidth"), avg_width);
        self
    }

    /// Write the `/MaxWidth` attribute.
    pub fn max_width(&mut self, max_width: f32) -> &mut Self {
        self.pair(Name(b"MaxWidth"), max_width);
        self
    }

    /// Write the `/MissingWidth` attribute.
    pub fn missing_width(&mut self, missing_width: f32) -> &mut Self {
        self.pair(Name(b"MissingWidth"), missing_width);
        self
    }

    /// Write the `/FontFile` attribute, referecing Type 1 font data.
    pub fn font_file(&mut self, id: Ref) -> &mut Self {
        self.pair(Name(b"FontFile"), id);
        self
    }

    /// Write the `/FontFile2` attribute, referencing TrueType font data. PDF
    /// 1.1+.
    pub fn font_file2(&mut self, id: Ref) -> &mut Self {
        self.pair(Name(b"FontFile2"), id);
        self
    }

    /// Write the `/FontFile3` attribute, referencing CFF font data. PDF 1.2+ or
    /// PDF 1.3+ for CID-keyed fonts.
    pub fn font_file3(&mut self, id: Ref) -> &mut Self {
        self.pair(Name(b"FontFile3"), id);
        self
    }

    /// Write the `/CharSet` attribute, encoding the character names of a font
    /// subset as a string. This is only relevant for Type 1 fonts. PDF 1.1+.
    pub fn char_set(&mut self, names: Str) -> &mut Self {
        self.pair(Name(b"CharSet"), names);
        self
    }
}

deref!('a, FontDescriptor<'a> => Dict<'a>, dict);

/// The width of a font's glyphs.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
#[allow(missing_docs)]
pub enum FontStretch {
    UltraCondensed,
    ExtraCondensed,
    Condensed,
    SemiCondensed,
    Normal,
    SemiExpanded,
    Expanded,
    ExtraExpanded,
    UltraExpanded,
}

impl FontStretch {
    pub(crate) fn to_name(self) -> Name<'static> {
        match self {
            Self::UltraCondensed => Name(b"UltraCondensed"),
            Self::ExtraCondensed => Name(b"ExtraCondensed"),
            Self::Condensed => Name(b"Condensed"),
            Self::SemiCondensed => Name(b"SemiCondensed"),
            Self::Normal => Name(b"Normal"),
            Self::SemiExpanded => Name(b"SemiExpanded"),
            Self::Expanded => Name(b"Expanded"),
            Self::ExtraExpanded => Name(b"ExtraExpanded"),
            Self::UltraExpanded => Name(b"UltraExpanded"),
        }
    }
}

bitflags::bitflags! {
    /// Bitflags describing various characteristics of fonts.
    pub struct FontFlags: u32 {
        /// All glyphs have the same width.
        const FIXED_PITCH = 1 << 0;
        /// Glyphs have short strokes at their stems.
        const SERIF = 1 << 1;
        /// The font contains glyphs not in the Adobe standard Latin character
        /// set.
        const SYMBOLIC = 1 << 2;
        /// The glyphs resemeble cursive handwritiwng.
        const SCRIPT = 1 << 3;
        /// The font only uses glyphs in the Adobe standard Latin character set.
        const NON_SYMBOLIC = 1 << 5;
        /// The glyphs are slanted to the right.
        const ITALIC = 1 << 6;
        /// The font does not contain lowercase letters.
        const ALL_CAP = 1 << 16;
        /// The font's lowercase letters are similar to the uppercase ones, but
        /// smaller.
        const SMALL_CAP = 1 << 17;
        /// Ensures that bold glyphs are painted with more pixels than normal
        /// glyphs even at very small sizes.
        const FORCE_BOLD = 1 << 18;
    }
}

/// Writer for a _character map stream_.
///
/// This struct is created by [`PdfWriter::cmap`].
pub struct Cmap<'a> {
    stream: Stream<'a>,
}

impl<'a> Cmap<'a> {
    /// Create a new character map writer.
    pub(crate) fn start(mut stream: Stream<'a>) -> Self {
        stream.pair(Name(b"Type"), Name(b"CMap"));
        Self { stream }
    }

    /// Write the `/CMapName` attribute. Required.
    pub fn name(&mut self, name: Name) -> &mut Self {
        self.pair(Name(b"CMapName"), name);
        self
    }

    /// Write the `/CIDSystemInfo` attribute. Required.
    pub fn system_info(&mut self, info: SystemInfo) -> &mut Self {
        info.write(self.insert(Name(b"CIDSystemInfo")));
        self
    }
}

deref!('a, Cmap<'a> => Stream<'a>, stream);

/// A builder for a `/ToUnicode` character map stream.
pub struct UnicodeCmap {
    buf: Vec<u8>,
    mappings: Vec<u8>,
    count: i32,
}

impl UnicodeCmap {
    /// Create a new, empty unicode character map.
    pub fn new(name: Name, info: SystemInfo) -> Self {
        // https://www.adobe.com/content/dam/acom/en/devnet/font/pdfs/5014.CIDFont_Spec.pdf

        let mut buf = Vec::new();

        // Static header.
        buf.extend(b"%!PS-Adobe-3.0 Resource-CMap\n");
        buf.extend(b"%%DocumentNeededResources: procset CIDInit\n");
        buf.extend(b"%%IncludeResource: procset CIDInit\n");

        // Dynamic header.
        buf.extend(b"%%BeginResource: CMap ");
        buf.extend(name.0);
        buf.push(b'\n');
        buf.extend(b"%%Title: (");
        buf.extend(name.0);
        buf.push(b' ');
        buf.extend(info.registry.0);
        buf.push(b' ');
        buf.extend(info.ordering.0);
        buf.push(b' ');
        buf.push_int(info.supplement);
        buf.extend(b")\n");
        buf.extend(b"%%Version: 1\n");
        buf.extend(b"%%EndComments\n");

        // General body.
        buf.extend(b"/CIDInit /ProcSet findresource begin\n");
        buf.extend(b"12 dict begin\n");
        buf.extend(b"begincmap\n");
        buf.extend(b"/CIDSystemInfo 3 dict dup begin\n");
        buf.extend(b"    /Registry ");
        buf.push_val(info.registry);
        buf.extend(b" def\n");
        buf.extend(b"    /Ordering ");
        buf.push_val(info.ordering);
        buf.extend(b" def\n");
        buf.extend(b"    /Supplement ");
        buf.push_val(info.supplement);
        buf.extend(b" def\n");
        buf.extend(b"end def\n");
        buf.extend(b"/CMapName ");
        buf.push_val(name);
        buf.extend(b" def\n");
        buf.extend(b"/CMapVersion 1 def\n");
        buf.extend(b"/CMapType 0 def\n");

        // We just cover the whole unicode codespace.
        buf.extend(b"1 begincodespacerange\n");
        buf.extend(b"<0000> <ffff>\n");
        buf.extend(b"endcodespacerange\n");

        Self { buf, mappings: vec![], count: 0 }
    }

    /// Add a mapping from a glyph ID to a unicode codepoint.
    pub fn pair(&mut self, glyph: u16, codepoint: char) {
        self.mappings.push(b'<');
        self.mappings.push_hex_u16(glyph);
        self.mappings.extend(b"> <");

        let mut utf16 = [0u16; 2];
        for &mut part in codepoint.encode_utf16(&mut utf16) {
            self.mappings.push_hex_u16(part);
        }

        self.mappings.extend(b">\n");
        self.count += 1;

        // At most 100 lines per range.
        if self.count >= 100 {
            self.flush_range();
        }
    }

    /// Finish building the character map.
    pub fn finish(mut self) -> Vec<u8> {
        // Flush the in-progress range.
        self.flush_range();

        // End of body.
        self.buf.extend(b"endcmap\n");
        self.buf.extend(b"CMapName currentdict /CMap defineresource pop\n");
        self.buf.extend(b"end\n");
        self.buf.extend(b"end\n");
        self.buf.extend(b"%%EndResource\n");
        self.buf.extend(b"%%EOF");

        self.buf
    }

    fn flush_range(&mut self) {
        if self.count > 0 {
            self.buf.push_int(self.count);
            self.buf.extend(b" beginbfchar\n");
            self.buf.extend(&self.mappings);
            self.buf.extend(b"endbfchar\n");
        }

        self.count = 0;
        self.mappings.clear();
    }
}

/// Specifics about a character collection.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub struct SystemInfo<'a> {
    /// The issuer of the collection.
    pub registry: Str<'a>,
    /// A unique name of the collection within the registry.
    pub ordering: Str<'a>,
    /// The supplement number (i.e. the version).
    pub supplement: i32,
}

impl SystemInfo<'_> {
    fn write(&self, obj: Obj<'_>) {
        obj.dict()
            .pair(Name(b"Registry"), self.registry)
            .pair(Name(b"Ordering"), self.ordering)
            .pair(Name(b"Supplement"), self.supplement);
    }
}