docxide-pdf 0.12.2

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

use std::collections::{HashMap, HashSet};
use std::path::PathBuf;
use std::time::Instant;

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

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

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

/// Metrics extracted from a font file during embedding. Does not include font resolution
/// metadata (path, face index, synthetic bold) which is tracked separately.
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>,
}

/// Font metrics bundled with resolution metadata from the font discovery phase.
struct ResolvedFont {
    metrics: FontMetrics,
    synthetic_bold: bool,
    font_path: Option<PathBuf>,
    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<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.
    #[allow(dead_code)]
    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 = 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<ResolvedFont> {
    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(metrics) = embedded_fonts.get(&embedded_key).and_then(|d| embed(d, 0)) {
        return Some(ResolvedFont {
            metrics,
            synthetic_bold: false,
            font_path: None,
            face_index: 0,
        });
    }

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

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"),
        FontFamily::Script | FontFamily::Decorative => Some("Times New Roman"),
        _ => None,
    }
}

fn known_font_alias(name: &str) -> Option<&'static str> {
    match name {
        "Palatino Linotype" => Some("Palatino"),
        "標楷體" | "DFKai-SB" => Some("BiauKai"),
        _ => 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",
            "Hiragino Sans GB",
            "Hiragino Sans GB W3",
            "PMingLiU",
            "MingLiU",
            "Songti TC",
            "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 = 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);
    let table_entry = lookup_font_table(font_table, primary);

    let try_cjk_fallback = |tc: &mut dyn FnMut(&str) -> Option<ResolvedFont>| {
        cjk_fallback_fonts().iter().find_map(|cjk_font| {
            log::debug!("Trying CJK fallback \"{cjk_font}\" for \"{primary}\"");
            let m = tc(cjk_font)?;
            log::info!("Font substitution: {primary} → CJK fallback \"{cjk_font}\"");
            Some(m)
        })
    };

    // 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 = table_entry
        .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 alias = known_font_alias(primary)?;
            let m = try_candidate(alias)?;
            log::info!("Font substitution: {primary} → alias \"{alias}\"");
            Some(m)
        })
        .or_else(|| {
            let entry = table_entry?;
            // Try CJK fallback before family fallback — family fonts (TNR, Courier)
            // lack CJK glyphs and would produce squares
            if needs_cjk {
                if let Some(m) = try_cjk_fallback(&mut try_candidate) {
                    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;
            }
            try_cjk_fallback(&mut try_candidate)
        });

    // Compute which CJK chars are missing from the resolved font
    let missing_cjk = if needs_cjk {
        let covered: HashSet<char> = result
            .as_ref()
            .map(|r| r.metrics.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(r) => FontEntry {
            pdf_name,
            font_ref,
            widths_1000: r.metrics.widths_1000,
            line_h_ratio: Some(r.metrics.line_h_ratio),
            ascender_ratio: Some(r.metrics.ascender_ratio),
            char_to_gid: Some(r.metrics.char_to_gid),
            char_widths_1000: Some(r.metrics.char_widths_1000),
            kern_pairs: if r.metrics.kern_pairs.is_empty() {
                None
            } else {
                Some(r.metrics.kern_pairs)
            },
            synthetic_bold: r.synthetic_bold,
            missing_cjk_chars: missing_cjk,
            font_path: r.font_path,
            face_index: r.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
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::model::VertAlign;

    #[test]
    fn test_primary_font_name_simple() {
        assert_eq!(primary_font_name("Arial"), "Arial");
        assert_eq!(primary_font_name("Times New Roman"), "Times New Roman");
    }

    #[test]
    fn test_primary_font_name_with_fallback() {
        assert_eq!(primary_font_name("Arial; Helvetica"), "Arial");
        assert_eq!(primary_font_name("Calibri; sans-serif"), "Calibri");
    }

    #[test]
    fn test_primary_font_name_with_whitespace() {
        assert_eq!(primary_font_name("  Arial  ; Helvetica"), "Arial");
    }

    #[test]
    fn test_primary_font_name_empty() {
        assert_eq!(primary_font_name(""), "");
    }

    fn make_run(font: &str, bold: bool, italic: bool) -> Run {
        Run {
            text: String::new(),
            font_name: font.to_string(),
            font_size: 12.0,
            bold,
            italic,
            underline: false,
            strikethrough: false,
            dstrike: false,
            color: None,
            highlight: None,
            shading: None,
            vertical_align: VertAlign::Baseline,
            text_shadow: None,
            text_glow: None,
            text_outline: None,
            text_fill: None,
            vanish: false,
            small_caps: false,
            caps: false,
            char_style_id: None,
            lang: None,
            char_spacing: 0.0,
            text_scale: 100.0,
            east_asia_font_name: None,
            is_tab: false,
            is_line_break: false,
            field_code: None,
            hyperlink_url: None,
            inline_image: None,
            footnote_id: None,
            is_footnote_ref_mark: false,
            kern_threshold: None,
            font_size_from_default: false,
            font_name_from_default: false,
        }
    }

    #[test]
    fn test_font_key_regular() {
        let run = make_run("Arial", false, false);
        let mut buf = String::new();
        assert_eq!(font_key_buf(&run, &mut buf), "Arial");
    }

    #[test]
    fn test_font_key_bold() {
        let run = make_run("Arial", true, false);
        let mut buf = String::new();
        assert_eq!(font_key_buf(&run, &mut buf), "Arial/B");
    }

    #[test]
    fn test_font_key_italic() {
        let run = make_run("Arial", false, true);
        let mut buf = String::new();
        assert_eq!(font_key_buf(&run, &mut buf), "Arial/I");
    }

    #[test]
    fn test_font_key_bold_italic() {
        let run = make_run("Arial", true, true);
        let mut buf = String::new();
        assert_eq!(font_key_buf(&run, &mut buf), "Arial/BI");
    }

    #[test]
    fn test_font_key_with_fallback_font() {
        let run = make_run("Calibri; sans-serif", false, false);
        let mut buf = String::new();
        assert_eq!(font_key_buf(&run, &mut buf), "Calibri");
    }
}