dxpdf 0.2.7

//! Paint phase — iterate DrawCommands and emit Skia PDF canvas operations.

use std::collections::HashMap;
use std::rc::Rc;

use skia_safe::{
    path_effect::PathEffect, pdf, Color4f, Data, FontMgr, Paint, Path, PathBuilder, PathFillType,
};

use crate::render::dimension::Pt;
use crate::render::error::RenderError;
use crate::render::fonts;
use crate::render::layout::draw_command::{
    DrawCommand, LayoutedPage, ResolvedDashPattern, ResolvedFill, ResolvedLineCap,
    ResolvedLineJoin, ResolvedStroke,
};
use crate::render::resolve::drawing_color::Rgba;
use crate::render::resolve::images::MediaEntry;
use crate::render::resolve::shape_geometry::{PathVerb, SubPath};
use crate::render::skia_conv::{to_color4f, to_line, to_point, to_rect, to_size};

/// Target resolution for embedded images (pixels per inch).
/// 150 DPI balances print quality with file size; matches LibreOffice.
const IMAGE_TARGET_DPI: f32 = 150.0;
/// Conversion factor from PDF points to target pixels.
const IMAGE_DPI_SCALE: f32 = IMAGE_TARGET_DPI / 72.0;

/// Render laid-out pages to PDF bytes via Skia.
pub fn render_to_pdf(pages: &[LayoutedPage], font_mgr: &FontMgr) -> Result<Vec<u8>, RenderError> {
    let mut pdf_bytes: Vec<u8> = Vec::new();
    let pdf_metadata = pdf::Metadata {
        encoding_quality: Some(85),
        ..Default::default()
    };
    let mut doc = pdf::new_document(&mut pdf_bytes, Some(&pdf_metadata));
    let mut font_cache = fonts::FontCache::new();
    // Cache decoded Skia images across pages, keyed by Rc pointer identity.
    // Avoids re-copying and re-decoding the same image bytes on every page
    // (e.g. a logo repeated in headers/footers).
    let mut image_cache: HashMap<*const [u8], skia_safe::Image> = HashMap::new();

    for page in pages {
        let mut on_page = doc.begin_page(to_size(page.page_size), None);
        {
            let canvas = on_page.canvas();
            render_page(canvas, page, font_mgr, &mut font_cache, &mut image_cache);
        }
        doc = on_page.end_page();
    }

    doc.close();
    Ok(pdf_bytes)
}

fn render_page(
    canvas: &skia_safe::Canvas,
    page: &LayoutedPage,
    font_mgr: &FontMgr,
    font_cache: &mut fonts::FontCache,
    image_cache: &mut HashMap<*const [u8], skia_safe::Image>,
) {
    for cmd in &page.commands {
        match cmd {
            DrawCommand::Text {
                position,
                text,
                font_family,
                char_spacing,
                font_size,
                bold,
                italic,
                color,
            } => {
                let font = font_cache.get(font_mgr, font_family, *font_size, *bold, *italic);
                log::trace!(
                    "[paint] '{}' → font='{}' size={:.1}pt bold={} italic={}",
                    &text[..text.len().min(30)],
                    font.typeface().family_name(),
                    font_size.raw(),
                    bold,
                    italic,
                );
                let mut paint = Paint::default();
                paint.set_anti_alias(true);
                paint.set_color4f(to_color4f(*color), None);

                if char_spacing.abs() > Pt::ZERO {
                    // §17.3.2.35 w:spacing — draw each character with
                    // explicit spacing to match the measured fragment width.
                    let char_count = text.chars().count();
                    let glyphs = font.text_to_glyphs_vec(&**text);
                    // Batch path: use text_to_glyphs + get_widths when glyph
                    // count matches char count (common Latin/CJK text).
                    // Fallback to per-char measure_str for ligatures or
                    // complex scripts where counts diverge.
                    let batch_widths = if glyphs.len() == char_count {
                        let mut widths = vec![0f32; glyphs.len()];
                        font.get_widths(&glyphs, &mut widths);
                        Some(widths)
                    } else {
                        None
                    };

                    let mut cursor = *position;
                    let mut buf = [0u8; 4];
                    for (i, ch) in text.chars().enumerate() {
                        let s = ch.encode_utf8(&mut buf);
                        let w = if let Some(ref widths) = batch_widths {
                            widths[i]
                        } else {
                            font.measure_str(&*s, None).0
                        };
                        canvas.draw_str(&*s, to_point(cursor), font, &paint);
                        cursor.x += Pt::new(w) + *char_spacing;
                    }
                } else {
                    canvas.draw_str(text, to_point(*position), font, &paint);
                }
            }
            DrawCommand::Underline { line, color, width }
            | DrawCommand::Line { line, color, width } => {
                let mut paint = Paint::default();
                paint.set_anti_alias(true);
                paint.set_stroke(true);
                paint.set_stroke_width(f32::from(*width));
                paint.set_color4f(to_color4f(*color), None);

                let (start, end) = to_line(*line);
                canvas.draw_line(start, end, &paint);
            }
            DrawCommand::Image { rect, image_data } => {
                let ptr_key: *const [u8] = Rc::as_ptr(&image_data.data);
                if let Some(image) = image_cache.get(&ptr_key) {
                    canvas.draw_image_rect(image, None, to_rect(*rect), &Paint::default());
                } else {
                    let decoded = decode_image(image_data);
                    if let Some(image) = decoded {
                        let image = downsample_if_oversize(image, *rect);
                        canvas.draw_image_rect(&image, None, to_rect(*rect), &Paint::default());
                        image_cache.insert(ptr_key, image);
                    } else {
                        let magic = &image_data.data[..image_data.data.len().min(4)];
                        log::warn!(
                            "[paint] unsupported image format {:?} — could not decode {} bytes \
                             (magic: {:02x?}); image will be blank",
                            image_data.format,
                            image_data.data.len(),
                            magic,
                        );
                    }
                }
            }
            DrawCommand::Rect { rect, color } => {
                let mut paint = Paint::default();
                paint.set_anti_alias(false);
                paint.set_color4f(to_color4f(*color), None);
                canvas.draw_rect(to_rect(*rect), &paint);
            }
            DrawCommand::LinkAnnotation { rect, url } => {
                let mut url_bytes = url.as_bytes().to_vec();
                url_bytes.push(0);
                let url_data = Data::new_copy(&url_bytes);
                canvas.annotate_rect_with_url(to_rect(*rect), &url_data);
            }
            DrawCommand::InternalLink { rect, destination } => {
                let mut name_bytes = destination.as_bytes().to_vec();
                name_bytes.push(0);
                let name_data = Data::new_copy(&name_bytes);
                canvas.annotate_link_to_destination(to_rect(*rect), &name_data);
            }
            DrawCommand::NamedDestination { position, name } => {
                let mut name_bytes = name.as_bytes().to_vec();
                name_bytes.push(0);
                let name_data = Data::new_copy(&name_bytes);
                canvas.annotate_named_destination(to_point(*position), &name_data);
            }
            DrawCommand::Path {
                origin,
                rotation,
                flip_h,
                flip_v,
                extent,
                paths,
                fill,
                stroke,
                effects: _,
            } => {
                canvas.save();
                // Translate to the shape's origin.
                canvas.translate((origin.x.raw(), origin.y.raw()));
                // Apply flip / rotation around the shape's center.
                let cx = extent.width.raw() / 2.0;
                let cy = extent.height.raw() / 2.0;
                let rot_deg = rotation.raw() as f32 / 60_000.0;
                if *flip_h || *flip_v || rot_deg != 0.0 {
                    canvas.translate((cx, cy));
                    if rot_deg != 0.0 {
                        canvas.rotate(rot_deg, None);
                    }
                    let sx = if *flip_h { -1.0 } else { 1.0 };
                    let sy = if *flip_v { -1.0 } else { 1.0 };
                    if sx != 1.0 || sy != 1.0 {
                        canvas.scale((sx, sy));
                    }
                    canvas.translate((-cx, -cy));
                }
                let skia_path = build_skia_path(paths);
                if let Some(paint) = fill_to_paint(fill) {
                    canvas.draw_path(&skia_path, &paint);
                }
                if let Some(stroke) = stroke.as_ref() {
                    let paint = stroke_to_paint(stroke);
                    // Only stroke subpaths whose .stroked flag is set.
                    let strokable = build_skia_path_stroked_only(paths);
                    canvas.draw_path(&strokable, &paint);
                }
                canvas.restore();
            }
        }
    }
}

// ── Shape path helpers ──────────────────────────────────────────────────────

/// Build a Skia path from all subpaths, regardless of stroke flag. Used for
/// fill painting — OOXML fills every subpath's interior per its fill mode.
fn build_skia_path(paths: &[SubPath]) -> Path {
    let mut builder = PathBuilder::new();
    builder.set_fill_type(PathFillType::Winding);
    for sub in paths {
        emit_subpath(&mut builder, sub);
    }
    builder.snapshot()
}

/// Build a Skia path limited to subpaths with `.stroked == true`.
fn build_skia_path_stroked_only(paths: &[SubPath]) -> Path {
    let mut builder = PathBuilder::new();
    for sub in paths {
        if sub.stroked {
            emit_subpath(&mut builder, sub);
        }
    }
    builder.snapshot()
}

fn emit_subpath(builder: &mut PathBuilder, sub: &SubPath) {
    // Track the last point manually: `PathBuilder` has no `last_pt()` query,
    // and `arc_to` needs the current pen position to derive the bounding oval.
    let mut last_pt: (f32, f32) = (0.0, 0.0);
    for verb in &sub.verbs {
        match verb {
            PathVerb::MoveTo(p) => {
                let pt = (p.x.raw(), p.y.raw());
                builder.move_to(pt);
                last_pt = pt;
            }
            PathVerb::LineTo(p) => {
                let pt = (p.x.raw(), p.y.raw());
                builder.line_to(pt);
                last_pt = pt;
            }
            PathVerb::QuadTo(c, p) => {
                let pt = (p.x.raw(), p.y.raw());
                builder.quad_to((c.x.raw(), c.y.raw()), pt);
                last_pt = pt;
            }
            PathVerb::CubicTo(c1, c2, p) => {
                let pt = (p.x.raw(), p.y.raw());
                builder.cubic_to((c1.x.raw(), c1.y.raw()), (c2.x.raw(), c2.y.raw()), pt);
                last_pt = pt;
            }
            PathVerb::ArcTo {
                radii,
                start_angle,
                swing_angle,
            } => {
                // OOXML arcTo positions the arc on the oval centered at the
                // current pen point offset by (-wr, -hr) — §20.1.9.3. Skia's
                // PathBuilder::arc_to expects the bounding oval; we compute
                // it from the current point + radii. Angles are kept in
                // OOXML's convention (0° = 3 o'clock, clockwise +) which
                // matches Skia.
                let (cx, cy) = last_pt;
                let (wr, hr) = (radii.width.raw(), radii.height.raw());
                let oval = skia_safe::Rect::from_xywh(cx - wr, cy - hr, wr * 2.0, hr * 2.0);
                let start_deg = start_angle.raw() as f32 / 60_000.0;
                let sweep_deg = swing_angle.raw() as f32 / 60_000.0;
                builder.arc_to(oval, start_deg, sweep_deg, false);
                // Update last point to the arc's end position.
                let end_rad = (start_deg + sweep_deg).to_radians();
                last_pt = (cx + wr * end_rad.cos(), cy + hr * end_rad.sin());
            }
            PathVerb::Close => {
                builder.close();
            }
        }
    }
}

fn fill_to_paint(fill: &ResolvedFill) -> Option<Paint> {
    match fill {
        ResolvedFill::None => None,
        ResolvedFill::Solid(color) => {
            let mut paint = Paint::default();
            paint.set_anti_alias(true);
            paint.set_style(skia_safe::PaintStyle::Fill);
            paint.set_color4f(rgba_to_color4f(*color), None);
            Some(paint)
        }
        ResolvedFill::Gradient(_) => {
            log::warn!("paint: gradient fill not yet rendered (Tier 2)");
            None
        }
        ResolvedFill::Blip(_) => {
            log::warn!("paint: blip fill not yet rendered (Tier 2)");
            None
        }
        ResolvedFill::Pattern(_) => {
            log::warn!("paint: pattern fill not yet rendered (Tier 3)");
            None
        }
    }
}

fn stroke_to_paint(stroke: &ResolvedStroke) -> Paint {
    let mut paint = Paint::default();
    paint.set_anti_alias(true);
    paint.set_style(skia_safe::PaintStyle::Stroke);
    paint.set_stroke_width(stroke.width.raw());
    paint.set_color4f(rgba_to_color4f(stroke.color), None);
    paint.set_stroke_cap(match stroke.cap {
        ResolvedLineCap::Butt => skia_safe::PaintCap::Butt,
        ResolvedLineCap::Round => skia_safe::PaintCap::Round,
        ResolvedLineCap::Square => skia_safe::PaintCap::Square,
    });
    paint.set_stroke_join(match stroke.join {
        ResolvedLineJoin::Round => skia_safe::PaintJoin::Round,
        ResolvedLineJoin::Bevel => skia_safe::PaintJoin::Bevel,
        ResolvedLineJoin::Miter => skia_safe::PaintJoin::Miter,
    });
    if let ResolvedDashPattern::Dashes(dashes) = &stroke.dash {
        if !dashes.is_empty() {
            let floats: Vec<f32> = dashes.iter().map(|p| p.raw()).collect();
            if let Some(effect) = PathEffect::dash(&floats, 0.0) {
                paint.set_path_effect(effect);
            }
        }
    }
    paint
}

fn rgba_to_color4f(c: Rgba) -> Color4f {
    Color4f::new(c.r, c.g, c.b, c.a)
}

/// Decode a `MediaEntry` to a Skia image, dispatching on format.
///
/// Returns `None` if the format is unsupported or the data is malformed.
fn decode_image(entry: &MediaEntry) -> Option<skia_safe::Image> {
    use crate::model::ImageFormat;
    match entry.format {
        ImageFormat::Emf => crate::render::emf::decode_emf_bitmap(&entry.data),
        // All other formats are handled by Skia's built-in decoder.
        _ => skia_safe::Image::from_encoded(Data::new_copy(&entry.data)),
    }
}

/// Downsample an image if its native pixel dimensions significantly exceed
/// the display dimensions at `IMAGE_TARGET_DPI`. Uses Mitchell-Netravali
/// cubic filtering for high-quality results.
fn downsample_if_oversize(
    image: skia_safe::Image,
    rect: crate::render::geometry::PtRect,
) -> skia_safe::Image {
    use skia_safe::CubicResampler;
    use skia_safe::{AlphaType, ColorType, ImageInfo, SamplingOptions};

    let target_w = (rect.size.width.raw() * IMAGE_DPI_SCALE).ceil() as i32;
    let target_h = (rect.size.height.raw() * IMAGE_DPI_SCALE).ceil() as i32;
    if image.width() > target_w && image.height() > target_h && target_w > 0 && target_h > 0 {
        log::debug!(
            "[paint] downsampling image {}×{} → {}×{} (display {:.0}×{:.0}pt @ {:.0} DPI)",
            image.width(),
            image.height(),
            target_w,
            target_h,
            rect.size.width.raw(),
            rect.size.height.raw(),
            IMAGE_TARGET_DPI,
        );
        // Draw scaled image onto an opaque surface so Skia applies JPEG
        // encoding (encoding_quality) instead of lossless FlateDecode.
        let info = ImageInfo::new(
            (target_w, target_h),
            ColorType::RGBA8888,
            AlphaType::Opaque,
            None,
        );
        let sampling = SamplingOptions::from(CubicResampler::mitchell());
        if let Some(mut surface) = skia_safe::surfaces::raster(&info, None, None) {
            let dst = skia_safe::Rect::from_iwh(target_w, target_h);
            surface.canvas().draw_image_rect_with_sampling_options(
                &image,
                None,
                dst,
                sampling,
                &Paint::default(),
            );
            surface.image_snapshot()
        } else {
            image
        }
    } else {
        image
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::render::geometry::{PtOffset, PtSize};
    use crate::render::resolve::color::RgbColor;
    use std::rc::Rc;

    fn test_font_mgr() -> FontMgr {
        FontMgr::new()
    }

    // ── render_to_pdf integration ───────────────────────────────────

    #[test]
    fn render_text_command_produces_pdf() {
        let font_mgr = test_font_mgr();
        let page = LayoutedPage {
            commands: vec![DrawCommand::Text {
                position: PtOffset::new(Pt::new(72.0), Pt::new(100.0)),
                text: "Hello world".into(),
                font_family: Rc::from("Helvetica"),
                char_spacing: Pt::ZERO,
                font_size: Pt::new(12.0),
                bold: false,
                italic: false,
                color: RgbColor::BLACK,
            }],
            page_size: PtSize::new(Pt::new(612.0), Pt::new(792.0)),
        };

        let pdf_bytes = render_to_pdf(&[page], &font_mgr).expect("render_to_pdf must succeed");
        assert!(pdf_bytes.len() > 100, "PDF output must be non-trivial");
        assert_eq!(&pdf_bytes[..5], b"%PDF-", "output must be valid PDF");
    }

    #[test]
    fn render_text_with_char_spacing_produces_pdf() {
        let font_mgr = test_font_mgr();
        let page = LayoutedPage {
            commands: vec![DrawCommand::Text {
                position: PtOffset::new(Pt::new(72.0), Pt::new(100.0)),
                text: "Spaced".into(),
                font_family: Rc::from("Helvetica"),
                char_spacing: Pt::new(2.0),
                font_size: Pt::new(14.0),
                bold: true,
                italic: false,
                color: RgbColor::BLACK,
            }],
            page_size: PtSize::new(Pt::new(612.0), Pt::new(792.0)),
        };

        let pdf_bytes = render_to_pdf(&[page], &font_mgr).expect("render_to_pdf must succeed");
        assert!(pdf_bytes.len() > 100);
        assert_eq!(&pdf_bytes[..5], b"%PDF-");
    }

    #[test]
    fn render_empty_text_produces_pdf() {
        let font_mgr = test_font_mgr();
        let page = LayoutedPage {
            commands: vec![DrawCommand::Text {
                position: PtOffset::new(Pt::new(72.0), Pt::new(100.0)),
                text: Rc::from(""),
                font_family: Rc::from("Helvetica"),
                char_spacing: Pt::ZERO,
                font_size: Pt::new(12.0),
                bold: false,
                italic: false,
                color: RgbColor::BLACK,
            }],
            page_size: PtSize::new(Pt::new(612.0), Pt::new(792.0)),
        };

        let pdf_bytes = render_to_pdf(&[page], &font_mgr).expect("empty text must not panic");
        assert_eq!(&pdf_bytes[..5], b"%PDF-");
    }

    // ── DrawCommand::Path ─────────────────────────────────────────────

    #[test]
    fn render_path_solid_filled_rect() {
        use crate::model::dimension::Dimension;
        use crate::model::PathFillMode;
        use crate::render::layout::draw_command::{
            ResolvedDashPattern, ResolvedFill, ResolvedLineCap, ResolvedLineJoin, ResolvedStroke,
        };
        use crate::render::resolve::drawing_color::Rgba;
        use crate::render::resolve::shape_geometry::{PathVerb, SubPath};

        let verbs = vec![
            PathVerb::MoveTo(PtOffset::new(Pt::ZERO, Pt::ZERO)),
            PathVerb::LineTo(PtOffset::new(Pt::new(100.0), Pt::ZERO)),
            PathVerb::LineTo(PtOffset::new(Pt::new(100.0), Pt::new(50.0))),
            PathVerb::LineTo(PtOffset::new(Pt::ZERO, Pt::new(50.0))),
            PathVerb::Close,
        ];
        let page = LayoutedPage {
            commands: vec![DrawCommand::Path {
                origin: PtOffset::new(Pt::new(72.0), Pt::new(100.0)),
                rotation: Dimension::new(0),
                flip_h: false,
                flip_v: false,
                extent: PtSize::new(Pt::new(100.0), Pt::new(50.0)),
                paths: vec![SubPath {
                    verbs,
                    fill_mode: PathFillMode::Norm,
                    stroked: true,
                }],
                fill: ResolvedFill::Solid(Rgba {
                    r: 1.0,
                    g: 0.0,
                    b: 0.0,
                    a: 1.0,
                }),
                stroke: Some(ResolvedStroke {
                    width: Pt::new(1.0),
                    color: Rgba::BLACK,
                    dash: ResolvedDashPattern::Solid,
                    cap: ResolvedLineCap::Butt,
                    join: ResolvedLineJoin::Miter,
                }),
                effects: vec![],
            }],
            page_size: PtSize::new(Pt::new(612.0), Pt::new(792.0)),
        };
        let pdf = render_to_pdf(&[page], &test_font_mgr()).expect("render path");
        assert_eq!(&pdf[..5], b"%PDF-");
    }

    #[test]
    fn render_path_dashed_line() {
        use crate::model::dimension::Dimension;
        use crate::model::PathFillMode;
        use crate::render::layout::draw_command::{
            ResolvedDashPattern, ResolvedFill, ResolvedLineCap, ResolvedLineJoin, ResolvedStroke,
        };
        use crate::render::resolve::drawing_color::Rgba;
        use crate::render::resolve::shape_geometry::{PathVerb, SubPath};

        let page = LayoutedPage {
            commands: vec![DrawCommand::Path {
                origin: PtOffset::new(Pt::new(50.0), Pt::new(50.0)),
                rotation: Dimension::new(0),
                flip_h: false,
                flip_v: false,
                extent: PtSize::new(Pt::new(100.0), Pt::new(0.0)),
                paths: vec![SubPath {
                    verbs: vec![
                        PathVerb::MoveTo(PtOffset::new(Pt::ZERO, Pt::ZERO)),
                        PathVerb::LineTo(PtOffset::new(Pt::new(100.0), Pt::ZERO)),
                    ],
                    fill_mode: PathFillMode::None,
                    stroked: true,
                }],
                fill: ResolvedFill::None,
                stroke: Some(ResolvedStroke {
                    width: Pt::new(2.0),
                    color: Rgba {
                        r: 0.85,
                        g: 0.6,
                        b: 0.2,
                        a: 1.0,
                    },
                    dash: ResolvedDashPattern::Dashes(vec![Pt::new(6.0), Pt::new(3.0)]),
                    cap: ResolvedLineCap::Round,
                    join: ResolvedLineJoin::Round,
                }),
                effects: vec![],
            }],
            page_size: PtSize::new(Pt::new(612.0), Pt::new(792.0)),
        };
        let pdf = render_to_pdf(&[page], &test_font_mgr()).expect("render dashed line");
        assert_eq!(&pdf[..5], b"%PDF-");
    }

    #[test]
    fn render_unicode_text_produces_pdf() {
        let font_mgr = test_font_mgr();
        let page = LayoutedPage {
            commands: vec![DrawCommand::Text {
                position: PtOffset::new(Pt::new(72.0), Pt::new(100.0)),
                text: "Ärzte für Ökologie — 日本語".into(),
                font_family: Rc::from("Helvetica"),
                char_spacing: Pt::ZERO,
                font_size: Pt::new(11.0),
                bold: false,
                italic: false,
                color: RgbColor::BLACK,
            }],
            page_size: PtSize::new(Pt::new(612.0), Pt::new(792.0)),
        };

        let pdf_bytes = render_to_pdf(&[page], &font_mgr).expect("unicode text must not panic");
        assert_eq!(&pdf_bytes[..5], b"%PDF-");
    }
}