#![doc = include_str!("../README.md")]

use std::fmt::{Display, Formatter, Write};

use dioxus_core::exports::bumpalo;
use dioxus_core::IntoVNode;
use dioxus_core::*;

fn app(_cx: Scope) -> Element {
    None
}

pub struct SsrRenderer {
    vdom: VirtualDom,
    cfg: SsrConfig,
}

impl SsrRenderer {
    pub fn new(cfg: impl FnOnce(SsrConfig) -> SsrConfig) -> Self {
        Self {
            cfg: cfg(SsrConfig::default()),
            vdom: VirtualDom::new(app),
        }
    }

    pub fn render_lazy<'a>(&'a mut self, f: LazyNodes<'a, '_>) -> String {
        let scope = self.vdom.base_scope();
        let factory = NodeFactory::new(scope);

        let root = f.into_vnode(factory);
        format!(
            "{:}",
            TextRenderer {
                cfg: self.cfg.clone(),
                root: &root,
                vdom: Some(&self.vdom),
                bump: bumpalo::Bump::new(),
            }
        )
    }
}

#[allow(clippy::needless_lifetimes)]
pub fn render_lazy<'a>(f: LazyNodes<'a, '_>) -> String {
    let vdom = VirtualDom::new(app);
    let scope: *const ScopeState = vdom.base_scope();

    // Safety
    //
    // The lifetimes bounds on LazyNodes are really complicated - they need to support the nesting restrictions in
    // regular component usage. The <'a> lifetime is used to enforce that all calls of IntoVnode use the same allocator.
    //
    // When LazyNodes are provided, they are FnOnce, but do not come with a allocator selected to borrow from. The <'a>
    // lifetime is therefore longer than the lifetime of the allocator which doesn't exist... yet.
    //
    // Therefore, we cast our local bump allocator to the right lifetime. This is okay because our usage of the bump
    // arena is *definitely* shorter than the <'a> lifetime, and we return *owned* data - not borrowed data.
    let scope = unsafe { &*scope };

    let root = f.into_vnode(NodeFactory::new(scope));

    let vdom = Some(&vdom);

    let ssr_renderer = TextRenderer {
        cfg: SsrConfig::default(),
        root: &root,
        vdom,
        bump: bumpalo::Bump::new(),
    };
    let r = ssr_renderer.to_string();
    drop(ssr_renderer);
    r
}

pub fn render_vdom(dom: &VirtualDom) -> String {
    format!("{:}", TextRenderer::from_vdom(dom, SsrConfig::default()))
}

pub fn pre_render_vdom(dom: &VirtualDom) -> String {
    format!(
        "{:}",
        TextRenderer::from_vdom(dom, SsrConfig::default().pre_render(true))
    )
}

pub fn render_vdom_cfg(dom: &VirtualDom, cfg: impl FnOnce(SsrConfig) -> SsrConfig) -> String {
    format!(
        "{:}",
        TextRenderer::from_vdom(dom, cfg(SsrConfig::default()))
    )
}

pub fn render_vdom_scope(vdom: &VirtualDom, scope: ScopeId) -> Option<String> {
    Some(format!(
        "{:}",
        TextRenderer {
            cfg: SsrConfig::default(),
            root: vdom.get_scope(scope).unwrap().root_node(),
            vdom: Some(vdom),
            bump: bumpalo::Bump::new()
        }
    ))
}

/// A configurable text renderer for the Dioxus VirtualDOM.
///
///
/// ## Details
///
/// This uses the `Formatter` infrastructure so you can write into anything that supports `write_fmt`. We can't accept
/// any generic writer, so you need to "Display" the text renderer. This is done through `format!` or `format_args!`
///
/// ## Example
/// ```ignore
/// static App: Component = |cx| cx.render(rsx!(div { "hello world" }));
/// let mut vdom = VirtualDom::new(App);
/// vdom.rebuild();
///
/// let renderer = TextRenderer::new(&vdom);
/// let output = format!("{}", renderer);
/// assert_eq!(output, "<div>hello world</div>");
/// ```
pub struct TextRenderer<'a, 'b, 'c> {
    vdom: Option<&'c VirtualDom>,
    root: &'b VNode<'a>,
    cfg: SsrConfig,
    bump: bumpalo::Bump,
}

impl<'a: 'c, 'c> Display for TextRenderer<'a, '_, 'c> {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        let mut last_node_was_text = false;
        self.html_render(self.root, f, 0, &mut last_node_was_text)
    }
}

impl<'a> TextRenderer<'a, '_, 'a> {
    pub fn from_vdom(vdom: &'a VirtualDom, cfg: SsrConfig) -> Self {
        Self {
            cfg,
            root: vdom.base_scope().root_node(),
            vdom: Some(vdom),
            bump: bumpalo::Bump::new(),
        }
    }
}

impl<'a: 'c, 'c> TextRenderer<'a, '_, 'c> {
    fn html_render(
        &self,
        node: &VNode,
        f: &mut impl Write,
        il: u16,
        last_node_was_text: &mut bool,
    ) -> std::fmt::Result {
        match &node {
            VNode::Text(text) => {
                if *last_node_was_text {
                    write!(f, "<!--spacer-->")?;
                }

                if self.cfg.indent {
                    for _ in 0..il {
                        write!(f, "    ")?;
                    }
                }

                *last_node_was_text = true;

                write!(f, "{}", text.text)?
            }
            VNode::Placeholder(_anchor) => {
                *last_node_was_text = false;

                if self.cfg.indent {
                    for _ in 0..il {
                        write!(f, "    ")?;
                    }
                }
                write!(f, "<!--placeholder-->")?;
            }
            VNode::Element(el) => {
                *last_node_was_text = false;

                if self.cfg.indent {
                    for _ in 0..il {
                        write!(f, "    ")?;
                    }
                }

                write!(f, "<{}", el.tag)?;

                let inner_html = render_attributes(el.attributes.iter(), f)?;

                match self.cfg.newline {
                    true => writeln!(f, ">")?,
                    false => write!(f, ">")?,
                }

                if let Some(inner_html) = inner_html {
                    write!(f, "{}", inner_html)?;
                } else {
                    let mut last_node_was_text = false;
                    for child in el.children {
                        self.html_render(child, f, il + 1, &mut last_node_was_text)?;
                    }
                }

                if self.cfg.newline {
                    writeln!(f)?;
                }
                if self.cfg.indent {
                    for _ in 0..il {
                        write!(f, "    ")?;
                    }
                }

                write!(f, "</{}>", el.tag)?;
                if self.cfg.newline {
                    writeln!(f)?;
                }
            }
            VNode::Fragment(frag) => {
                for child in frag.children {
                    self.html_render(child, f, il + 1, last_node_was_text)?;
                }
            }
            VNode::Component(vcomp) => {
                let idx = vcomp.scope.get().unwrap();

                if let (Some(vdom), false) = (self.vdom, self.cfg.skip_components) {
                    let new_node = vdom.get_scope(idx).unwrap().root_node();
                    self.html_render(new_node, f, il + 1, last_node_was_text)?;
                } else {
                }
            }
            VNode::TemplateRef(tmpl) => {
                if let Some(vdom) = self.vdom {
                    let template_id = &tmpl.template_id;
                    let dynamic_context = &tmpl.dynamic_context;
                    vdom.with_template(template_id, move |tmpl| {
                        match tmpl {
                            Template::Static(s) => {
                                for r in s.root_nodes {
                                    self.render_template_node(
                                        &s.nodes,
                                        &s.nodes[r.0],
                                        dynamic_context,
                                        f,
                                        last_node_was_text,
                                        il,
                                    )?;
                                }
                            }
                            Template::Owned(o) => {
                                for r in &o.root_nodes {
                                    self.render_template_node(
                                        &o.nodes,
                                        &o.nodes[r.0],
                                        dynamic_context,
                                        f,
                                        last_node_was_text,
                                        il,
                                    )?;
                                }
                            }
                        };
                        Ok(())
                    })?
                } else {
                    panic!("Cannot render template without vdom");
                }
            }
        }
        Ok(())
    }

    fn render_template_node<TemplateNodes, Attributes, V, Children, Listeners, TextSegments, Text>(
        &self,
        template_nodes: &TemplateNodes,
        node: &TemplateNode<Attributes, V, Children, Listeners, TextSegments, Text>,
        dynamic_context: &TemplateContext,
        f: &mut impl Write,
        last_node_was_text: &mut bool,
        il: u16,
    ) -> std::fmt::Result
    where
        TemplateNodes:
            AsRef<[TemplateNode<Attributes, V, Children, Listeners, TextSegments, Text>]>,
        Attributes: AsRef<[TemplateAttribute<V>]>,
        Children: AsRef<[TemplateNodeId]>,
        Listeners: AsRef<[usize]>,
        Text: AsRef<str>,
        TextSegments: AsRef<[TextTemplateSegment<Text>]>,
        V: TemplateValue,
    {
        match &node.node_type {
            TemplateNodeType::Element(el) => {
                *last_node_was_text = false;

                if self.cfg.indent {
                    for _ in 0..il {
                        write!(f, "    ")?;
                    }
                }

                write!(f, "<{}", el.tag)?;

                let mut inner_html = None;

                let mut attr_iter = el.attributes.as_ref().iter().peekable();

                while let Some(attr) = attr_iter.next() {
                    match attr.attribute.namespace {
                        None => {
                            if attr.attribute.name == "dangerous_inner_html" {
                                inner_html = {
                                    let text = match &attr.value {
                                        TemplateAttributeValue::Static(val) => {
                                            val.allocate(&self.bump).as_text().unwrap()
                                        }
                                        TemplateAttributeValue::Dynamic(idx) => dynamic_context
                                            .resolve_attribute(*idx)
                                            .as_text()
                                            .unwrap(),
                                    };
                                    Some(text)
                                }
                            } else if is_boolean_attribute(attr.attribute.name) {
                                match &attr.value {
                                    TemplateAttributeValue::Static(val) => {
                                        let val = val.allocate(&self.bump);
                                        if val.is_truthy() {
                                            write!(f, " {}=\"{}\"", attr.attribute.name, val)?
                                        }
                                    }
                                    TemplateAttributeValue::Dynamic(idx) => {
                                        let val = dynamic_context.resolve_attribute(*idx);
                                        if val.is_truthy() {
                                            write!(f, " {}=\"{}\"", attr.attribute.name, val)?
                                        }
                                    }
                                }
                            } else {
                                match &attr.value {
                                    TemplateAttributeValue::Static(val) => {
                                        let val = val.allocate(&self.bump);
                                        write!(f, " {}=\"{}\"", attr.attribute.name, val)?
                                    }
                                    TemplateAttributeValue::Dynamic(idx) => {
                                        let val = dynamic_context.resolve_attribute(*idx);
                                        write!(f, " {}=\"{}\"", attr.attribute.name, val)?
                                    }
                                }
                            }
                        }

                        Some(ns) => {
                            // write the opening tag
                            write!(f, " {}=\"", ns)?;
                            let mut cur_ns_el = attr;
                            loop {
                                match &attr.value {
                                    TemplateAttributeValue::Static(val) => {
                                        let val = val.allocate(&self.bump);
                                        write!(f, "{}:{};", cur_ns_el.attribute.name, val)?;
                                    }
                                    TemplateAttributeValue::Dynamic(idx) => {
                                        let val = dynamic_context.resolve_attribute(*idx);
                                        write!(f, "{}:{};", cur_ns_el.attribute.name, val)?;
                                    }
                                }
                                match attr_iter.peek() {
                                    Some(next_attr)
                                        if next_attr.attribute.namespace == Some(ns) =>
                                    {
                                        cur_ns_el = attr_iter.next().unwrap();
                                    }
                                    _ => break,
                                }
                            }
                            // write the closing tag
                            write!(f, "\"")?;
                        }
                    }
                }

                match self.cfg.newline {
                    true => writeln!(f, ">")?,
                    false => write!(f, ">")?,
                }

                if let Some(inner_html) = inner_html {
                    write!(f, "{}", inner_html)?;
                } else {
                    let mut last_node_was_text = false;
                    for child in el.children.as_ref() {
                        self.render_template_node(
                            template_nodes,
                            &template_nodes.as_ref()[child.0],
                            dynamic_context,
                            f,
                            &mut last_node_was_text,
                            il + 1,
                        )?;
                    }
                }

                if self.cfg.newline {
                    writeln!(f)?;
                }
                if self.cfg.indent {
                    for _ in 0..il {
                        write!(f, "    ")?;
                    }
                }

                write!(f, "</{}>", el.tag)?;
                if self.cfg.newline {
                    writeln!(f)?;
                }
            }
            TemplateNodeType::Text(txt) => {
                if *last_node_was_text {
                    write!(f, "<!--spacer-->")?;
                }

                if self.cfg.indent {
                    for _ in 0..il {
                        write!(f, "    ")?;
                    }
                }

                *last_node_was_text = true;

                let text = dynamic_context.resolve_text(txt);

                write!(f, "{}", text)?
            }
            TemplateNodeType::DynamicNode(idx) => {
                let node = dynamic_context.resolve_node(*idx);
                self.html_render(node, f, il, last_node_was_text)?;
            }
        }
        Ok(())
    }
}

fn render_attributes<'a, 'b: 'a, I>(
    attrs: I,
    f: &mut impl Write,
) -> Result<Option<&'b str>, std::fmt::Error>
where
    I: Iterator<Item = &'a Attribute<'b>>,
{
    let mut inner_html = None;
    let mut attr_iter = attrs.peekable();

    while let Some(attr) = attr_iter.next() {
        match attr.attribute.namespace {
            None => {
                if attr.attribute.name == "dangerous_inner_html" {
                    inner_html = Some(attr.value.as_text().unwrap())
                } else {
                    if is_boolean_attribute(attr.attribute.name) && !attr.value.is_truthy() {
                        continue;
                    }
                    write!(f, " {}=\"{}\"", attr.attribute.name, attr.value)?
                }
            }
            Some(ns) => {
                // write the opening tag
                write!(f, " {}=\"", ns)?;
                let mut cur_ns_el = attr;
                loop {
                    write!(f, "{}:{};", cur_ns_el.attribute.name, cur_ns_el.value)?;
                    match attr_iter.peek() {
                        Some(next_attr) if next_attr.attribute.namespace == Some(ns) => {
                            cur_ns_el = attr_iter.next().unwrap();
                        }
                        _ => break,
                    }
                }
                // write the closing tag
                write!(f, "\"")?;
            }
        }
    }
    Ok(inner_html)
}

fn is_boolean_attribute(attribute: &'static str) -> bool {
    matches!(
        attribute,
        "allowfullscreen"
            | "allowpaymentrequest"
            | "async"
            | "autofocus"
            | "autoplay"
            | "checked"
            | "controls"
            | "default"
            | "defer"
            | "disabled"
            | "formnovalidate"
            | "hidden"
            | "ismap"
            | "itemscope"
            | "loop"
            | "multiple"
            | "muted"
            | "nomodule"
            | "novalidate"
            | "open"
            | "playsinline"
            | "readonly"
            | "required"
            | "reversed"
            | "selected"
            | "truespeed"
    )
}

#[derive(Clone, Debug, Default)]
pub struct SsrConfig {
    /// currently not supported - control if we indent the HTML output
    indent: bool,

    /// Control if elements are written onto a new line
    newline: bool,

    /// Choose to write ElementIDs into elements so the page can be re-hydrated later on
    pre_render: bool,

    // Currently not implemented
    // Don't proceed onto new components. Instead, put the name of the component.
    // TODO: components don't have names :(
    skip_components: bool,
}

impl SsrConfig {
    pub fn indent(mut self, a: bool) -> Self {
        self.indent = a;
        self
    }
    pub fn newline(mut self, a: bool) -> Self {
        self.newline = a;
        self
    }
    pub fn pre_render(mut self, a: bool) -> Self {
        self.pre_render = a;
        self
    }
    pub fn skip_components(mut self, a: bool) -> Self {
        self.skip_components = a;
        self
    }
}