hti_svg/

lib.rs

use base64::{engine::general_purpose::STANDARD as BASE64, Engine as _};
use hti_core::*;

pub fn emit_svg(scene: &Scene) -> String {
    let vp = scene.viewport;
    let mut out = String::with_capacity(64 * 1024);

    // ── Header ────────────────────────────────────────────────────────────────
    out.push_str(&format!(
        r#"<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="{:.2}" height="{:.2}" viewBox="{:.2} {:.2} {:.2} {:.2}">"#,
        vp.width, vp.height, vp.x, vp.y, vp.width, vp.height
    ));

    // ── Defs ──────────────────────────────────────────────────────────────────
    out.push_str("<defs>");

    // Gradient defs
    for gdef in &scene.gradient_defs {
        let angle_rad = gdef.gradient.angle_deg.to_radians();
        let (x1, y1, x2, y2) = gradient_coords(angle_rad);
        out.push_str(&format!(
            r#"<linearGradient id="{}" x1="{:.4}" y1="{:.4}" x2="{:.4}" y2="{:.4}" gradientUnits="objectBoundingBox">"#,
            gdef.id, x1, y1, x2, y2
        ));
        for stop in &gdef.gradient.stops {
            out.push_str(&format!(
                r#"<stop offset="{:.4}" stop-color="{}" stop-opacity="{:.4}"/>"#,
                stop.position,
                stop.color.to_hex(),
                stop.color.a as f32 / 255.0
            ));
        }
        out.push_str("</linearGradient>");
    }

    // Blur filter defs (box-shadow)
    for f in &scene.blur_filters {
        // Extend filter region to avoid clipping the blur
        out.push_str(&format!(
            r#"<filter id="{}" x="-50%" y="-50%" width="200%" height="200%"><feGaussianBlur in="SourceGraphic" stdDeviation="{:.2}"/></filter>"#,
            f.id, f.std_deviation
        ));
    }

    // Clip path defs
    for node in &scene.nodes {
        if let SceneNode::Clip(clip) = node {
            out.push_str(&format!(
                r#"<clipPath id="clip{}"><rect x="{:.2}" y="{:.2}" width="{:.2}" height="{:.2}" rx="{:.2}"/></clipPath>"#,
                clip.id,
                clip.rect.x,
                clip.rect.y,
                clip.rect.width,
                clip.rect.height,
                clip.border_radius
            ));
        }
    }

    // Backdrop blur defs (glass effect).
    let has_backdrop = emit_backdrop_defs(&mut out, scene);
    let drawable_count = scene
        .nodes
        .iter()
        .filter(|n| !matches!(n, SceneNode::Clip(_)))
        .count();
    if has_backdrop {
        emit_stack_defs(&mut out, drawable_count);
    }

    out.push_str("</defs>");

    // ── Scene nodes ───────────────────────────────────────────────────────────
    if has_backdrop {
        let mut draw_idx = 0usize;
        for node in &scene.nodes {
            match node {
                SceneNode::Clip(_) => {}
                SceneNode::Rect(r) => {
                    if r.backdrop_blur_radius > 0.0 && draw_idx > 0 {
                        emit_backdrop_layer(&mut out, r, draw_idx);
                    }
                    emit_node_with_id(&mut out, node, draw_idx);
                    draw_idx += 1;
                }
                SceneNode::Image(_) | SceneNode::Text(_) => {
                    emit_node_with_id(&mut out, node, draw_idx);
                    draw_idx += 1;
                }
            }
        }
    } else {
        for node in &scene.nodes {
            match node {
                SceneNode::Clip(_) => {} // already in defs
                SceneNode::Rect(r) => emit_rect(&mut out, r),
                SceneNode::Image(img) => emit_image(&mut out, img),
                SceneNode::Text(t) => emit_text(&mut out, t),
            }
        }
    }

    out.push_str("</svg>");
    out
}

// ─── Rect ─────────────────────────────────────────────────────────────────────

fn emit_backdrop_defs(out: &mut String, scene: &Scene) -> bool {
    let mut has_backdrop = false;
    let mut draw_idx = 0usize;

    for node in &scene.nodes {
        match node {
            SceneNode::Clip(_) => continue,
            SceneNode::Rect(r) => {
                if r.backdrop_blur_radius > 0.0 {
                    has_backdrop = true;
                    let std_dev = (r.backdrop_blur_radius / 2.0).max(0.01);
                    out.push_str(&format!(
                        r#"<filter id="backdrop_blur{}" x="-30%" y="-30%" width="160%" height="160%"><feGaussianBlur in="SourceGraphic" stdDeviation="{:.2}"/></filter>"#,
                        draw_idx, std_dev
                    ));
                    out.push_str(&format!(
                        r#"<clipPath id="backdrop_clip{}"><rect x="{:.2}" y="{:.2}" width="{:.2}" height="{:.2}" rx="{:.2}"/></clipPath>"#,
                        draw_idx,
                        r.bounds.x,
                        r.bounds.y,
                        r.bounds.width,
                        r.bounds.height,
                        r.border_radius
                    ));
                }
            }
            SceneNode::Image(_) | SceneNode::Text(_) => {}
        }
        draw_idx += 1;
    }

    has_backdrop
}

fn emit_stack_defs(out: &mut String, drawable_count: usize) {
    if drawable_count == 0 {
        return;
    }
    out.push_str(r##"<g id="stack0"><use href="#node0"/></g>"##);
    for i in 1..drawable_count {
        out.push_str(&format!(
            r##"<g id="stack{}"><use href="#stack{}"/><use href="#node{}"/></g>"##,
            i,
            i - 1,
            i
        ));
    }
}

fn emit_backdrop_layer(out: &mut String, r: &RectSceneNode, draw_idx: usize) {
    if draw_idx == 0 {
        return;
    }

    let parent_clip = clip_attr_str(r.clip_id);
    out.push_str(&format!(r#"<g{}>"#, parent_clip));
    out.push_str(&format!(
        r##"<g clip-path="url(#backdrop_clip{})"><g filter="url(#backdrop_blur{})"><use href="#stack{}"/></g></g>"##,
        draw_idx,
        draw_idx,
        draw_idx - 1
    ));
    out.push_str("</g>\n");
}

fn emit_node_with_id(out: &mut String, node: &SceneNode, draw_idx: usize) {
    out.push_str(&format!(r#"<g id="node{}">"#, draw_idx));
    match node {
        SceneNode::Rect(r) => emit_rect(out, r),
        SceneNode::Image(img) => emit_image(out, img),
        SceneNode::Text(t) => emit_text(out, t),
        SceneNode::Clip(_) => {}
    }
    out.push_str("</g>\n");
}

fn emit_rect(out: &mut String, r: &RectSceneNode) {
    let fill = match &r.background {
        Background::None => "none".to_string(),
        Background::Color(c) => c.to_hex(),
        Background::LinearGradient(_) => {
            // gradient_id luôn có khi background là LinearGradient
            r.gradient_id
                .as_ref()
                .map(|id| format!("url(#{})", id))
                .unwrap_or_else(|| "none".to_string())
        }
    };

    let clip_attr = clip_attr_str(r.clip_id);
    let tf_attr = transform_attr_str(&r.transform);
    let filter_attr = r
        .filter_id
        .as_ref()
        .map(|id| format!(r#" filter="url(#{})" "#, id))
        .unwrap_or_default();

    if r.border_width > 0.0 {
        out.push_str(&format!(
            r#"<rect x="{:.2}" y="{:.2}" width="{:.2}" height="{:.2}" rx="{:.2}" fill="{}" stroke="{}" stroke-width="{:.2}" opacity="{:.4}"{}{}{}/>
"#,
            r.bounds.x,
            r.bounds.y,
            r.bounds.width,
            r.bounds.height,
            r.border_radius,
            fill,
            r.border_color.to_hex(),
            r.border_width,
            r.opacity,
            clip_attr,
            tf_attr,
            filter_attr
        ));
    } else {
        out.push_str(&format!(
            r#"<rect x="{:.2}" y="{:.2}" width="{:.2}" height="{:.2}" rx="{:.2}" fill="{}" opacity="{:.4}"{}{}{}/>
"#,
            r.bounds.x,
            r.bounds.y,
            r.bounds.width,
            r.bounds.height,
            r.border_radius,
            fill,
            r.opacity,
            clip_attr,
            tf_attr,
            filter_attr
        ));
    }
}

// ─── Image ────────────────────────────────────────────────────────────────────

fn emit_image(out: &mut String, img: &ImageSceneNode) {
    let b64 = BASE64.encode(&img.image_bytes);
    let href = format!("data:{};base64,{}", img.image_mime, b64);

    let clip_attr = clip_attr_str(img.clip_id);
    let tf_attr = transform_attr_str(&img.transform);

    // Tính placement rect và preserveAspectRatio dựa trên object-fit
    let (ix, iy, iw, ih, par, extra_clip) = calc_object_fit(img);

    // Nếu cover, cần clip thêm (trừ khi đã có clip_id)
    let image_clip = if extra_clip && img.clip_id.is_none() && img.border_radius == 0.0 {
        let cid = format!("imgc_{:.0}_{:.0}", img.bounds.x, img.bounds.y);
        // Emit inline clipPath — vì đây là per-image, dùng id duy nhất theo vị trí
        out.push_str(&format!(
            r#"<defs><clipPath id="{cid}"><rect x="{:.2}" y="{:.2}" width="{:.2}" height="{:.2}"/></clipPath></defs>
"#,
            img.bounds.x, img.bounds.y, img.bounds.width, img.bounds.height
        ));
        format!(r#" clip-path="url(#{cid})""#)
    } else {
        clip_attr.clone()
    };

    out.push_str(&format!(
        r#"<image x="{:.2}" y="{:.2}" width="{:.2}" height="{:.2}" href="{}" preserveAspectRatio="{}" opacity="{:.4}"{}{}/>
"#,
        ix, iy, iw, ih, href, par, img.opacity, image_clip, tf_attr
    ));
}

/// Tính (x, y, w, h, preserveAspectRatio, needs_extra_clip) cho image placement.
fn calc_object_fit(img: &ImageSceneNode) -> (f32, f32, f32, f32, &'static str, bool) {
    let b = img.bounds;
    let (iw, ih) = (img.intrinsic_width, img.intrinsic_height);
    let (px, py) = img.object_position;

    // Xác định SVG alignment string từ object-position (0.0–1.0)
    let align = position_to_align(px, py);

    match img.object_fit {
        ObjectFit::Fill => (b.x, b.y, b.w(), b.h(), "none", false),

        ObjectFit::Contain => {
            // Fit trong bounds, letterbox
            (
                b.x,
                b.y,
                b.w(),
                b.h(),
                Box::leak(format!("{} meet", align).into_boxed_str()),
                false,
            )
        }

        ObjectFit::Cover => {
            if iw <= 0.0 || ih <= 0.0 {
                // Không biết intrinsic size → dùng slice với bounds
                (
                    b.x,
                    b.y,
                    b.w(),
                    b.h(),
                    Box::leak(format!("{} slice", align).into_boxed_str()),
                    true,
                )
            } else {
                // Tính placement để cover bounds với đúng alignment
                let scale = f32::max(b.w() / iw, b.h() / ih);
                let sw = iw * scale;
                let sh = ih * scale;
                let x = b.x + (b.w() - sw) * px;
                let y = b.y + (b.h() - sh) * py;
                (x, y, sw, sh, "none", true)
            }
        }
    }
}

fn position_to_align(px: f32, py: f32) -> &'static str {
    match (quantize(px), quantize(py)) {
        (0, 0) => "xMinYMin",
        (1, 0) => "xMidYMin",
        (2, 0) => "xMaxYMin",
        (0, 1) => "xMinYMid",
        (1, 1) => "xMidYMid",
        (2, 1) => "xMaxYMid",
        (0, 2) => "xMinYMax",
        (1, 2) => "xMidYMax",
        _ => "xMaxYMax",
    }
}

fn quantize(v: f32) -> u8 {
    if v < 0.33 {
        0
    } else if v < 0.67 {
        1
    } else {
        2
    }
}

// Workaround: ObjectFit::Contain/Cover need the PAR string.
// We use 'static lifetime tricks. For correctness, use the full string.
trait BoundsExt {
    fn w(&self) -> f32;
    fn h(&self) -> f32;
}
impl BoundsExt for Rect {
    fn w(&self) -> f32 {
        self.width
    }
    fn h(&self) -> f32 {
        self.height
    }
}

// ─── Text ─────────────────────────────────────────────────────────────────────

fn emit_text(out: &mut String, t: &TextSceneNode) {
    let clip_attr = clip_attr_str(t.clip_id);
    let tf_attr = transform_attr_str(&t.transform);

    let font_weight = match t.font_weight {
        FontWeight::Normal => "normal".to_string(),
        FontWeight::Bold => "bold".to_string(),
        FontWeight::W(w) => w.to_string(),
    };
    let font_family = t.font_family.as_deref().unwrap_or("Arial");
    let (text_anchor, x_offset) = match t.text_align {
        TextAlign::Left => ("start", t.bounds.x),
        TextAlign::Center => ("middle", t.bounds.x + t.bounds.width / 2.0),
        TextAlign::Right => ("end", t.bounds.x + t.bounds.width),
    };

    out.push_str(&format!(
        r#"<text x="{:.2}" font-family="{}" font-size="{:.2}" font-weight="{}" fill="{}" text-anchor="{}" opacity="{:.4}"{}{}>"#,
        x_offset,
        font_family,
        t.font_size,
        font_weight,
        t.color.to_hex(),
        text_anchor,
        t.opacity,
        clip_attr,
        tf_attr
    ));

    let lines = if t.text_overflow == TextOverflow::Ellipsis && t.white_space == WhiteSpace::NoWrap
    {
        let mut v = t.lines.clone();
        if let Some(first) = v.first_mut() {
            *first = truncate_ellipsis(first, t.bounds.width, t.font_size);
        }
        v.truncate(1);
        v
    } else {
        t.lines.clone()
    };

    for (i, line) in lines.iter().enumerate() {
        let escaped = xml_escape(line);
        if i == 0 {
            let y = t.bounds.y + t.font_size; // first line baseline
            if t.letter_spacing != 0.0 {
                out.push_str(&format!(
                    r#"<tspan y="{:.2}" letter-spacing="{:.2}">{}</tspan>"#,
                    y, t.letter_spacing, escaped
                ));
            } else {
                out.push_str(&format!(r#"<tspan y="{:.2}">{}</tspan>"#, y, escaped));
            }
        } else {
            let dy = t.line_height_px;
            if t.letter_spacing != 0.0 {
                out.push_str(&format!(
                    r#"<tspan x="{:.2}" dy="{:.2}" letter-spacing="{:.2}">{}</tspan>"#,
                    x_offset, dy, t.letter_spacing, escaped
                ));
            } else {
                out.push_str(&format!(
                    r#"<tspan x="{:.2}" dy="{:.2}">{}</tspan>"#,
                    x_offset, dy, escaped
                ));
            }
        }
    }

    out.push_str("</text>\n");
}

// ─── Helpers ──────────────────────────────────────────────────────────────────

fn clip_attr_str(clip_id: Option<u32>) -> String {
    clip_id
        .map(|id| format!(r#" clip-path="url(#clip{})""#, id))
        .unwrap_or_default()
}

fn transform_attr_str(t: &Transform) -> String {
    let mut parts: Vec<String> = Vec::new();
    if t.translate_x != 0.0 || t.translate_y != 0.0 {
        parts.push(format!(
            "translate({:.2},{:.2})",
            t.translate_x, t.translate_y
        ));
    }
    if t.scale_x != 1.0 || t.scale_y != 1.0 {
        parts.push(format!("scale({:.4},{:.4})", t.scale_x, t.scale_y));
    }
    if t.rotate_deg != 0.0 {
        parts.push(format!("rotate({:.2})", t.rotate_deg));
    }
    if parts.is_empty() {
        String::new()
    } else {
        format!(r#" transform="{}""#, parts.join(" "))
    }
}

fn gradient_coords(angle_rad: f32) -> (f32, f32, f32, f32) {
    let x1 = 0.5 - 0.5 * angle_rad.sin();
    let y1 = 0.5 + 0.5 * angle_rad.cos();
    let x2 = 0.5 + 0.5 * angle_rad.sin();
    let y2 = 0.5 - 0.5 * angle_rad.cos();
    (x1, y1, x2, y2)
}

fn xml_escape(s: &str) -> String {
    s.replace('&', "&amp;")
        .replace('<', "&lt;")
        .replace('>', "&gt;")
        .replace('"', "&quot;")
}

fn truncate_ellipsis(text: &str, max_width: f32, font_size: f32) -> String {
    let approx_char_w = font_size * 0.55;
    let max_chars = (max_width / approx_char_w).floor() as usize;
    let chars: Vec<char> = text.chars().collect();
    if chars.len() <= max_chars {
        return text.to_string();
    }
    let s: String = chars[..max_chars.saturating_sub(1)].iter().collect();
    format!("{}…", s)
}

trait ColorHex {
    fn to_hex(&self) -> String;
}
impl ColorHex for Color {
    fn to_hex(&self) -> String {
        format!("#{:02x}{:02x}{:02x}", self.r, self.g, self.b)
    }
}