docxide-pdf 0.10.0

mod cache;
mod discovery;
mod embed;
mod encoding;

use std::collections::{HashMap, HashSet};

use pdf_writer::{Name, Pdf, Ref};

use crate::model::{FontFamily, FontTable, Run};

pub(crate) use encoding::{encode_as_gids, to_winansi_bytes};

/// Metrics returned from font embedding: widths, line-height ratio, ascender ratio,
/// char-to-gid mapping, per-char widths, and kerning pairs.
pub(crate) struct FontMetrics {
    pub(crate) widths_1000: Vec<f32>,
    pub(crate) line_h_ratio: f32,
    pub(crate) ascender_ratio: f32,
    pub(crate) char_to_gid: HashMap<char, u16>,
    pub(crate) char_widths_1000: HashMap<char, f32>,
    pub(crate) kern_pairs: HashMap<(u16, u16), f32>,
    pub(crate) synthetic_bold: bool,
    pub(crate) font_path: Option<std::path::PathBuf>,
    pub(crate) face_index: u32,
}

pub(crate) struct FontEntry {
    pub(crate) pdf_name: String,
    pub(crate) font_ref: Ref,
    pub(crate) widths_1000: Vec<f32>,
    pub(crate) line_h_ratio: Option<f32>,
    pub(crate) ascender_ratio: Option<f32>,
    pub(crate) char_to_gid: Option<HashMap<char, u16>>,
    pub(crate) char_widths_1000: Option<HashMap<char, f32>>,
    pub(crate) kern_pairs: Option<HashMap<(u16, u16), f32>>,
    pub(crate) synthetic_bold: bool,
    /// CJK chars requested but not present in this font (need fallback rendering).
    pub(crate) missing_cjk_chars: HashSet<char>,
    /// Font file path for glyph outline extraction (text warping).
    pub(crate) font_path: Option<std::path::PathBuf>,
    pub(crate) face_index: u32,
}

impl FontEntry {
    /// Width of a single character in 1000-units. Uses the per-char cache (covers
    /// all Unicode chars seen in the document), falls back to the WinAnsi table.
    pub(crate) fn char_width_1000(&self, ch: char) -> f32 {
        if let Some(w) = self.char_widths_1000.as_ref().and_then(|m| m.get(&ch)) {
            return *w;
        }
        let byte = encoding::char_to_winansi(ch);
        if byte >= 32 {
            self.widths_1000[(byte - 32) as usize]
        } else {
            0.0
        }
    }

    /// Width with CJK fallback: if this font is missing a CJK char, use the
    /// fallback font's width instead.
    pub(crate) fn char_width_1000_with_fallback(
        &self,
        ch: char,
        fallback: Option<&FontEntry>,
    ) -> f32 {
        let w = self.char_width_1000(ch);
        if w > 0.0 || !self.missing_cjk_chars.contains(&ch) {
            return w;
        }
        fallback
            .and_then(|fb| fb.char_widths_1000.as_ref()?.get(&ch).copied())
            .unwrap_or(0.0)
    }

    pub(crate) fn word_width(&self, word: &str, font_size: f32, kern: bool) -> f32 {
        if !kern || self.kern_pairs.is_none() {
            return word
                .chars()
                .map(|ch| self.char_width_1000(ch) * font_size / 1000.0)
                .sum();
        }
        let scale = font_size / 1000.0;
        let mut prev: Option<char> = None;
        let mut w: f32 = 0.0;
        for ch in word.chars() {
            if let Some(p) = prev {
                w += self.kern_1000(p, ch) * scale;
            }
            w += self.char_width_1000(ch) * scale;
            prev = Some(ch);
        }
        w
    }

    fn kern_1000(&self, left: char, right: char) -> f32 {
        let (Some(pairs), Some(c2g)) = (&self.kern_pairs, &self.char_to_gid) else {
            return 0.0;
        };
        c2g.get(&left)
            .zip(c2g.get(&right))
            .and_then(|(&l, &r)| pairs.get(&(l, r)))
            .copied()
            .unwrap_or(0.0)
    }

    pub(crate) fn space_width(&self, font_size: f32) -> f32 {
        self.char_width_1000(' ') * font_size / 1000.0
    }
}

pub(crate) fn primary_font_name(name: &str) -> &str {
    name.split(';').next().unwrap_or(name).trim()
}

/// Write the font key for a run into the provided buffer, returning it as a `&str`.
/// Avoids per-call heap allocation when callers reuse the buffer.
pub(crate) fn font_key_buf<'a>(run: &Run, buf: &'a mut String) -> &'a str {
    buf.clear();
    buf.push_str(primary_font_name(&run.font_name));
    match (run.bold, run.italic) {
        (true, true) => buf.push_str("/BI"),
        (true, false) => buf.push_str("/B"),
        (false, true) => buf.push_str("/I"),
        (false, false) => {}
    }
    buf.as_str()
}

pub(crate) fn font_key(run: &Run) -> String {
    let mut buf = String::new();
    font_key_buf(run, &mut buf);
    buf
}

pub(crate) type EmbeddedFonts = HashMap<(String, bool, bool), Vec<u8>>;

fn try_font(
    pdf: &mut Pdf,
    candidate: &str,
    bold: bool,
    italic: bool,
    font_ref: Ref,
    descriptor_ref: Ref,
    data_ref: Ref,
    alloc: &mut impl FnMut() -> Ref,
    embedded_fonts: &EmbeddedFonts,
    used_chars: &HashSet<char>,
) -> Option<FontMetrics> {
    let mut embed = |data: &[u8], face_index: u32| {
        embed::embed_truetype(
            pdf,
            font_ref,
            descriptor_ref,
            data_ref,
            candidate,
            data,
            face_index,
            used_chars,
            alloc,
        )
    };

    let embedded_key = (candidate.to_lowercase(), bold, italic);
    if let Some(mut metrics) = embedded_fonts.get(&embedded_key).and_then(|d| embed(d, 0)) {
        metrics.synthetic_bold = false;
        metrics.font_path = None;
        metrics.face_index = 0;
        return Some(metrics);
    }

    let (path, face_index, exact_match) = discovery::find_font_file(candidate, bold, italic)?;
    let data = std::fs::read(&path).ok()?;
    let mut metrics = embed(&data, face_index)?;
    metrics.synthetic_bold = bold && !exact_match;
    metrics.font_path = Some(path);
    metrics.face_index = face_index;
    Some(metrics)
}

fn lookup_font_table<'a>(
    font_table: &'a FontTable,
    name: &str,
) -> Option<&'a crate::model::FontTableEntry> {
    font_table.get(name).or_else(|| {
        let lower = name.to_lowercase();
        font_table
            .iter()
            .find(|(k, _)| k.to_lowercase() == lower)
            .map(|(_, v)| v)
    })
}

fn family_fallback(family: FontFamily) -> Option<&'static str> {
    match family {
        FontFamily::Roman => Some("Times New Roman"),
        FontFamily::Swiss => Some("Arial"),
        FontFamily::Modern => Some("Courier New"),
        _ => None,
    }
}

fn has_cjk_chars(chars: &HashSet<char>) -> bool {
    chars.iter().any(|&c| crate::docx::is_east_asian_char(c))
}

pub(crate) fn cjk_fallback_fonts() -> &'static [&'static str] {
    #[cfg(target_os = "macos")]
    {
        &[
            "Malgun Gothic",
            "AppleSD Gothic Neo",
            "Apple SD Gothic Neo",
            "Hiragino Sans W3",
            "Hiragino Kaku Gothic ProN W3",
            "Arial Unicode MS",
            "PingFang SC",
        ]
    }
    #[cfg(target_os = "linux")]
    {
        &[
            "Noto Sans CJK SC",
            "Noto Sans CJK KR",
            "Noto Sans CJK JP",
        ]
    }
    #[cfg(target_os = "windows")]
    {
        &[
            "Malgun Gothic",
            "Yu Gothic",
            "Microsoft YaHei",
        ]
    }
    #[cfg(not(any(target_os = "macos", target_os = "linux", target_os = "windows")))]
    {
        &[]
    }
}

pub(crate) fn register_font(
    pdf: &mut Pdf,
    font_name: &str,
    bold: bool,
    italic: bool,
    pdf_name: String,
    alloc: &mut impl FnMut() -> Ref,
    embedded_fonts: &EmbeddedFonts,
    used_chars: &HashSet<char>,
    font_table: &FontTable,
) -> FontEntry {
    let t0 = std::time::Instant::now();
    let font_ref = alloc();
    let descriptor_ref = alloc();
    let data_ref = alloc();

    let primary = primary_font_name(font_name);

    let mut try_candidate = |name: &str| {
        try_font(
            pdf,
            name,
            bold,
            italic,
            font_ref,
            descriptor_ref,
            data_ref,
            alloc,
            embedded_fonts,
            used_chars,
        )
    };

    let needs_cjk = has_cjk_chars(used_chars);

    // If the fontTable provides an altName, try it first — it's the document's
    // explicit mapping and more reliable than the system font index (which may
    // resolve a localized name like "바탕" to a different font than "Batang").
    let result = lookup_font_table(font_table, primary)
        .and_then(|entry| {
            let alt = entry.alt_name.as_ref()?;
            let m = try_candidate(alt)?;
            log::info!("Font substitution: {primary} → altName \"{alt}\"");
            Some(m)
        })
        .or_else(|| {
            font_name
                .split(';')
                .map(|s| s.trim())
                .find_map(|c| try_candidate(c))
        })
        .or_else(|| {
            let entry = lookup_font_table(font_table, primary)?;
            // Try CJK fallback before family fallback — family fonts (TNR, Courier)
            // lack CJK glyphs and would produce squares
            if needs_cjk {
                for cjk_font in cjk_fallback_fonts() {
                    if let Some(m) = try_candidate(cjk_font) {
                        log::info!(
                            "Font substitution: {primary} → CJK fallback \"{cjk_font}\""
                        );
                        return Some(m);
                    }
                }
            }
            let fallback = family_fallback(entry.family)?;
            let m = try_candidate(fallback)?;
            log::info!(
                "Font substitution: {primary} → family {:?} fallback \"{fallback}\"",
                entry.family
            );
            Some(m)
        })
        .or_else(|| {
            if !needs_cjk {
                return None;
            }
            // Font not in fontTable at all — try CJK fallback as last resort
            for cjk_font in cjk_fallback_fonts() {
                if let Some(m) = try_candidate(cjk_font) {
                    log::info!("Font substitution: {primary} → CJK fallback \"{cjk_font}\"");
                    return Some(m);
                }
            }
            None
        });

    // Compute which CJK chars are missing from the resolved font
    let missing_cjk = if needs_cjk {
        let covered: HashSet<char> = result
            .as_ref()
            .map(|m| m.char_to_gid.keys().copied().collect())
            .unwrap_or_default();
        used_chars
            .iter()
            .copied()
            .filter(|ch| !covered.contains(ch) && crate::docx::is_east_asian_char(*ch))
            .collect()
    } else {
        HashSet::new()
    };

    let entry = match result {
        Some(m) => FontEntry {
            pdf_name,
            font_ref,
            widths_1000: m.widths_1000,
            line_h_ratio: Some(m.line_h_ratio),
            ascender_ratio: Some(m.ascender_ratio),
            char_to_gid: Some(m.char_to_gid),
            char_widths_1000: Some(m.char_widths_1000),
            kern_pairs: if m.kern_pairs.is_empty() {
                None
            } else {
                Some(m.kern_pairs)
            },
            synthetic_bold: m.synthetic_bold,
            missing_cjk_chars: missing_cjk,
            font_path: m.font_path,
            face_index: m.face_index,
        },
        None => {
            log::warn!("Font not found: {font_name} bold={bold} italic={italic} — using Helvetica");
            pdf.type1_font(font_ref)
                .base_font(Name(b"Helvetica"))
                .encoding_predefined(Name(b"WinAnsiEncoding"));
            FontEntry {
                pdf_name,
                font_ref,
                widths_1000: encoding::helvetica_widths(),
                line_h_ratio: None,
                ascender_ratio: None,
                char_to_gid: None,
                char_widths_1000: None,
                kern_pairs: None,
                synthetic_bold: false,
                missing_cjk_chars: missing_cjk,
                font_path: None,
                face_index: 0,
            }
        }
    };

    log::debug!(
        "register_font: {font_name} bold={bold} italic={italic} → {:.1}ms",
        t0.elapsed().as_secs_f64() * 1000.0,
    );

    entry
}