use crate::primitive::{PointExt, SizeExt, TransformExt};
use crate::{paint, AbsExt, PdfOptions};
use bytemuck::TransparentWrapper;
use ecow::EcoString;
use krilla::action::{Action, LinkAction};
use krilla::annotation::{LinkAnnotation, Target};
use krilla::destination::XyzDestination;
use krilla::font::{GlyphId, GlyphUnits};
use krilla::path::PathBuilder;
use krilla::surface::Surface;
use krilla::{PageSettings, SerializeSettings, SvgSettings};
use std::collections::{BTreeMap, HashMap};
use std::ops::Range;
use std::sync::Arc;
use krilla::geom::Rect;
use typst_library::diag::{bail, SourceResult};
use typst_library::foundations::Datetime;
use typst_library::layout::{
    Abs, Frame, FrameItem, GroupItem, PagedDocument, Point, Size, Transform,
};
use typst_library::model::Destination;
use typst_library::text::{Font, Glyph, Lang, TextItem};
use typst_library::visualize::{
    FillRule, Geometry, Image, ImageKind, Paint, Path, PathItem, Shape,
};
use typst_syntax::Span;

#[derive(Debug, Clone)]
pub(crate) struct State {
    /// The full transform chain
    transform_chain: Transform,
    /// The transform of the current item.
    transform: Transform,
    /// The transform of first hard frame in the hierarchy.
    container_transform_chain: Transform,
    /// The size of the first hard frame in the hierarchy.
    size: Size,
}

impl State {
    /// Creates a new, clean state for a given `size`.
    fn new(
        size: Size,
        transform_chain: Transform,
        container_transform_chain: Transform,
    ) -> Self {
        Self {
            transform_chain,
            transform: Transform::identity(),
            container_transform_chain,
            size,
        }
    }

    pub fn size(&mut self, size: Size) {
        self.size = size;
    }

    pub fn transform(&mut self, transform: Transform) {
        self.transform = self.transform.pre_concat(transform);
        self.transform_chain = self.transform_chain.pre_concat(transform);
    }

    fn set_container_transform(&mut self) {
        self.container_transform_chain = self.transform_chain;
    }

    /// Creates the [`Transforms`] structure for the current item.
    pub fn transforms(&self, size: Size) -> Transforms {
        Transforms {
            transform_chain_: self.transform_chain,
            container_transform_chain: self.container_transform_chain,
            container_size: self.size,
            size,
        }
    }
}

pub(crate) struct FrameContext {
    states: Vec<State>,
    annotations: Vec<krilla::annotation::Annotation>,
}

impl FrameContext {
    pub fn new(size: Size) -> Self {
        Self {
            states: vec![State::new(size, Transform::identity(), Transform::identity())],
            annotations: vec![],
        }
    }

    pub fn push(&mut self) {
        self.states.push(self.states.last().unwrap().clone());
    }

    pub fn pop(&mut self) {
        self.states.pop();
    }

    pub fn state(&self) -> &State {
        self.states.last().unwrap()
    }

    pub fn state_mut(&mut self) -> &mut State {
        self.states.last_mut().unwrap()
    }
}

/// Subset of the state used to calculate the transform of gradients and patterns.
#[derive(Debug, Clone, Copy)]
pub(super) struct Transforms {
    /// The full transform chain.
    pub transform_chain_: Transform,
    /// The transform of first hard frame in the hierarchy.
    pub container_transform_chain: Transform,
    /// The size of the first hard frame in the hierarchy.
    pub container_size: Size,
    /// The size of the item.
    pub size: Size,
}

#[derive(TransparentWrapper)]
#[repr(transparent)]
struct PdfGlyph(Glyph);

impl krilla::font::Glyph for PdfGlyph {
    fn glyph_id(&self) -> GlyphId {
        GlyphId::new(self.0.id as u32)
    }

    fn text_range(&self) -> Range<usize> {
        self.0.range.start as usize..self.0.range.end as usize
    }

    fn x_advance(&self) -> f32 {
        self.0.x_advance.get() as f32
    }

    fn x_offset(&self) -> f32 {
        self.0.x_offset.get() as f32
    }

    fn y_offset(&self) -> f32 {
        0.0
    }

    fn y_advance(&self) -> f32 {
        0.0
    }
}

pub struct GlobalContext {
    fonts: HashMap<Font, krilla::font::Font>,
    // Note: In theory, the same image can have multiple spans
    // if it appears in the document multiple times. We just store the
    // first appearance, though.
    image_spans: HashMap<krilla::image::Image, Span>,
    languages: BTreeMap<Lang, usize>,
}

impl GlobalContext {
    pub fn new() -> Self {
        Self {
            fonts: HashMap::new(),
            image_spans: HashMap::new(),
            languages: BTreeMap::new(),
        }
    }
}

// TODO: Change rustybuzz cluster behavior so it works with ActualText

#[typst_macros::time(name = "write pdf")]
pub fn pdf(
    typst_document: &PagedDocument,
    options: &PdfOptions,
) -> SourceResult<Vec<u8>> {
    let version = match options.pdf_version {
        None => options.validator.recommended_version(),
        Some(v) => {
            if !options.validator.compatible_with_version(v) {
                let v_string = v.as_str();
                let s_string = options.validator.as_str();
                let h_message = format!(
                    "export using {} instead",
                    options.validator.recommended_version().as_str()
                );
                bail!(Span::detached(), "{v_string} is not compatible with standard {s_string}"; hint: "{h_message}");
            } else {
                v
            }
        }
    };

    let settings = SerializeSettings {
        compress_content_streams: true,
        no_device_cs: true,
        ascii_compatible: false,
        xmp_metadata: true,
        cmyk_profile: None,
        validator: options.validator,
        enable_tagging: false,
        pdf_version: version,
    };

    let mut document = krilla::Document::new_with(settings);
    let mut gc = GlobalContext::new();

    for typst_page in &typst_document.pages {
        let settings = PageSettings::new(
            typst_page.frame.width().to_f32(),
            typst_page.frame.height().to_f32(),
        );
        let mut page = document.start_page_with(settings);
        let mut surface = page.surface();
        let mut fc = FrameContext::new(typst_page.frame.size());
        // println!("{:?}", &typst_page.frame);
        process_frame(
            &mut fc,
            &typst_page.frame,
            typst_page.fill_or_transparent(),
            &mut surface,
            &mut gc,
        )?;
        surface.finish();

        for annotation in fc.annotations {
            page.add_annotation(annotation);
        }
    }

    let metadata = {
        let creator = format!("Typst {}", env!("CARGO_PKG_VERSION"));

        let mut metadata = krilla::metadata::Metadata::new()
            .creator(creator)
            .keywords(
                typst_document
                    .info
                    .keywords
                    .iter()
                    .map(EcoString::to_string)
                    .collect(),
            )
            .authors(
                typst_document.info.author.iter().map(EcoString::to_string).collect(),
            );

        let lang = gc.languages.iter().max_by_key(|(_, &count)| count).map(|(&l, _)| l);

        if let Some(lang) = lang {
            metadata = metadata.language(lang.as_str().to_string());
        }

        if let Some(title) = &typst_document.info.title {
            metadata = metadata.title(title.to_string());
        }

        if let Some(subject) = &typst_document.info.description {
            metadata = metadata.subject(subject.to_string());
        }

        if let Some(ident) = options.ident.custom() {
            metadata = metadata.subject(ident.to_string());
        }

        let tz = typst_document.info.date.is_auto();
        if let Some(date) = typst_document
            .info
            .date
            .unwrap_or(options.timestamp)
            .and_then(|d| krilla_date(d, tz))
        {
            metadata = metadata.modification_date(date).creation_date(date);
        }

        metadata
    };

    document.set_metadata(metadata);

    Ok(document.finish().unwrap())
}

fn krilla_date(datetime: Datetime, tz: bool) -> Option<krilla::metadata::DateTime> {
    let year = datetime.year().filter(|&y| y >= 0)? as u16;

    let mut krilla_date = krilla::metadata::DateTime::new(year);

    if let Some(month) = datetime.month() {
        krilla_date = krilla_date.month(month);
    }

    if let Some(day) = datetime.day() {
        krilla_date = krilla_date.day(day);
    }

    if let Some(h) = datetime.hour() {
        krilla_date = krilla_date.hour(h);
    }

    if let Some(m) = datetime.minute() {
        krilla_date = krilla_date.minute(m);
    }

    if let Some(s) = datetime.second() {
        krilla_date = krilla_date.second(s);
    }

    if tz {
        krilla_date = krilla_date.utc_offset_hour(0).utc_offset_minute(0);
    }

    Some(krilla_date)
}

pub fn process_frame(
    fc: &mut FrameContext,
    frame: &Frame,
    fill: Option<Paint>,
    surface: &mut Surface,
    gc: &mut GlobalContext,
) -> SourceResult<()> {
    fc.push();

    if frame.kind().is_hard() {
        fc.state_mut().set_container_transform();
        fc.state_mut().size(frame.size());
    }

    if let Some(fill) = fill {
        let shape = Geometry::Rect(frame.size()).filled(fill);
        handle_shape(fc, &shape, surface, gc)?;
    }

    for (point, item) in frame.items() {
        fc.push();
        fc.state_mut().transform(Transform::translate(point.x, point.y));
        match item {
            FrameItem::Group(g) => handle_group(fc, g, surface, gc)?,
            FrameItem::Text(t) => handle_text(fc, t, surface, gc)?,
            FrameItem::Shape(s, _) => handle_shape(fc, s, surface, gc)?,
            FrameItem::Image(image, size, span) => {
                handle_image(gc, fc, image, *size, surface, *span)?
            }
            FrameItem::Link(d, s) => write_link(fc, d, *s),
            FrameItem::Tag(_) => {}
        }

        fc.pop();
    }

    fc.pop();

    Ok(())
}

/// Save a link for later writing in the annotations dictionary.
fn write_link(fc: &mut FrameContext, dest: &Destination, size: Size) {
    let mut min_x = Abs::inf();
    let mut min_y = Abs::inf();
    let mut max_x = -Abs::inf();
    let mut max_y = -Abs::inf();

    let pos = Point::zero();

    // Compute the bounding box of the transformed link.
    for point in [
        pos,
        pos + Point::with_x(size.x),
        pos + Point::with_y(size.y),
        pos + size.to_point(),
    ] {
        let t = point.transform(fc.state().transform);
        min_x.set_min(t.x);
        min_y.set_min(t.y);
        max_x.set_max(t.x);
        max_y.set_max(t.y);
    }

    let x1 = min_x.to_f32();
    let x2 = max_x.to_f32();
    let y1 = min_y.to_f32();
    let y2 = max_y.to_f32();

    let rect = Rect::from_ltrb(x1, y1, x2, y2).unwrap();

    let target = match dest {
        Destination::Url(u) => {
            Target::Action(Action::Link(LinkAction::new(u.to_string())))
        }
        Destination::Position(p) => {
            // TODO: Ignore non-exported destinations
            Target::Destination(krilla::destination::Destination::Xyz(
                XyzDestination::new(p.page.get() - 1, p.point.as_krilla()),
            ))
        }
        // TODO: Implement
        Destination::Location(_) => return,
    };

    fc.annotations.push(LinkAnnotation::new(rect, target).into());
}

pub fn handle_group(
    fc: &mut FrameContext,
    group: &GroupItem,
    surface: &mut Surface,
    context: &mut GlobalContext,
) -> SourceResult<()> {
    fc.push();
    fc.state_mut().transform(group.transform);

    let clip_path = group
        .clip_path
        .as_ref()
        .and_then(|p| {
            let mut builder = PathBuilder::new();
            convert_path(p, &mut builder);
            builder.finish()
        })
        .and_then(|p| p.transform(fc.state().transform.as_krilla()));

    if let Some(clip_path) = &clip_path {
        surface.push_clip_path(clip_path, &krilla::path::FillRule::NonZero);
    }

    process_frame(fc, &group.frame, None, surface, context)?;

    if clip_path.is_some() {
        surface.pop();
    }

    fc.pop();

    Ok(())
}

pub fn handle_text(
    fc: &mut FrameContext,
    t: &TextItem,
    surface: &mut Surface,
    gc: &mut GlobalContext,
) -> SourceResult<()> {
    let font = gc
        .fonts
        .entry(t.font.clone())
        .or_insert_with(|| {
            krilla::font::Font::new(Arc::new(t.font.data().clone()), t.font.index(), true)
                // TODO: DOn't unwrap
                .unwrap()
        })
        .clone();

    *gc.languages.entry(t.lang).or_insert(0) += t.glyphs.len();

    let fill = paint::fill(
        gc,
        &t.fill,
        FillRule::NonZero,
        true,
        surface,
        fc.state().transforms(Size::zero()),
    )?;
    let text = t.text.as_str();
    let size = t.size;

    let glyphs: &[PdfGlyph] = TransparentWrapper::wrap_slice(t.glyphs.as_slice());

    surface.push_transform(&fc.state().transform.as_krilla());

    surface.fill_glyphs(
        krilla::geom::Point::from_xy(0.0, 0.0),
        fill,
        &glyphs,
        font.clone(),
        text,
        size.to_f32(),
        GlyphUnits::Normalized,
        false,
    );

    if let Some(stroke) = t
        .stroke
        .as_ref()
        .map(|s| paint::stroke(gc, s, true, surface, fc.state().transforms(Size::zero())))
    {
        let stroke = stroke?;

        surface.stroke_glyphs(
            krilla::geom::Point::from_xy(0.0, 0.0),
            stroke,
            &glyphs,
            font.clone(),
            text,
            size.to_f32(),
            GlyphUnits::Normalized,
            true,
        );
    }

    surface.pop();

    Ok(())
}

pub fn handle_image(
    gc: &mut GlobalContext,
    fc: &mut FrameContext,
    image: &Image,
    size: Size,
    surface: &mut Surface,
    span: Span,
) -> SourceResult<()> {
    surface.push_transform(&fc.state().transform.as_krilla());

    match image.kind() {
        ImageKind::Raster(raster) => {
            let image = match crate::image::raster(raster.clone()) {
                None => bail!(span, "failed to process image"),
                Some(i) => i,
            };

            if gc.image_spans.contains_key(&image) {
                gc.image_spans.insert(image.clone(), span);
            }

            surface.draw_image(image, size.as_krilla());
        }
        ImageKind::Svg(svg) => {
            surface.draw_svg(
                svg.tree(),
                size.as_krilla(),
                SvgSettings {
                    embed_text: !svg.flatten_text(),
                    ..Default::default()
                },
            );
        }
    }

    surface.pop();

    Ok(())
}

pub fn handle_shape(
    fc: &mut FrameContext,
    shape: &Shape,
    surface: &mut Surface,
    gc: &mut GlobalContext,
) -> SourceResult<()> {
    let mut path_builder = PathBuilder::new();

    match &shape.geometry {
        Geometry::Line(l) => {
            path_builder.move_to(0.0, 0.0);
            path_builder.line_to(l.x.to_f32(), l.y.to_f32());
        }
        Geometry::Rect(size) => {
            let w = size.x.to_f32();
            let h = size.y.to_f32();
            let rect = if w < 0.0 || h < 0.0 {
                // Skia doesn't normally allow for negative dimensions, but
                // Typst supports them, so we apply a transform if needed
                // Because this operation is expensive according to tiny-skia's
                // docs, we prefer to not apply it if not needed
                let transform =
                    krilla::geom::Transform::from_scale(w.signum(), h.signum());
                Rect::from_xywh(0.0, 0.0, w.abs(), h.abs())
                    .and_then(|rect| rect.transform(transform))
            } else {
                Rect::from_xywh(0.0, 0.0, w, h)
            };

            if let Some(rect) = rect {
                path_builder.push_rect(rect);
            }
        }
        Geometry::Path(p) => {
            convert_path(p, &mut path_builder);
        }
    }

    surface.push_transform(&fc.state().transform.as_krilla());

    if let Some(path) = path_builder.finish() {
        if let Some(paint) = &shape.fill {
            let fill = paint::fill(
                gc,
                &paint,
                shape.fill_rule,
                false,
                surface,
                fc.state().transforms(shape.geometry.bbox_size()),
            )?;
            surface.fill_path(&path, fill);
        }

        let stroke = shape.stroke.as_ref().and_then(|stroke| {
            if stroke.thickness.to_f32() > 0.0 {
                Some(stroke)
            } else {
                None
            }
        });

        if let Some(stroke) = &stroke {
            let stroke = paint::stroke(
                gc,
                stroke,
                false,
                surface,
                fc.state().transforms(shape.geometry.bbox_size()),
            )?;
            surface.stroke_path(&path, stroke);
        }
    }

    surface.pop();

    Ok(())
}

pub fn convert_path(path: &Path, builder: &mut PathBuilder) {
    for item in &path.0 {
        match item {
            PathItem::MoveTo(p) => builder.move_to(p.x.to_f32(), p.y.to_f32()),
            PathItem::LineTo(p) => builder.line_to(p.x.to_f32(), p.y.to_f32()),
            PathItem::CubicTo(p1, p2, p3) => builder.cubic_to(
                p1.x.to_f32(),
                p1.y.to_f32(),
                p2.x.to_f32(),
                p2.y.to_f32(),
                p3.x.to_f32(),
                p3.y.to_f32(),
            ),
            PathItem::ClosePath => builder.close(),
        }
    }
}