//! This module contains the implementation of abstract virtual node.

use std::cmp::PartialEq;
use std::iter::FromIterator;
use std::{fmt, mem};

use web_sys::Node;

use super::{Key, VChild, VComp, VList, VPortal, VSuspense, VTag, VText};
use crate::html::BaseComponent;
use crate::virtual_dom::VRaw;
use crate::AttrValue;

/// Bind virtual element to a DOM reference.
#[derive(Clone, PartialEq)]
#[must_use = "html does not do anything unless returned to Yew for rendering."]
pub enum VNode {
    /// A bind between `VTag` and `Element`.
    VTag(Box<VTag>),
    /// A bind between `VText` and `TextNode`.
    VText(VText),
    /// A bind between `VComp` and `Element`.
    VComp(VComp),
    /// A holder for a list of other nodes.
    VList(VList),
    /// A portal to another part of the document
    VPortal(VPortal),
    /// A holder for any `Node` (necessary for replacing node).
    VRef(Node),
    /// A suspendible document fragment.
    VSuspense(VSuspense),
    /// A raw HTML string, represented by [`AttrValue`](crate::AttrValue).
    ///
    /// Also see: [`VNode::from_html_unchecked`]
    VRaw(VRaw),
}

impl VNode {
    pub fn key(&self) -> Option<&Key> {
        match self {
            VNode::VComp(vcomp) => vcomp.key.as_ref(),
            VNode::VList(vlist) => vlist.key.as_ref(),
            VNode::VRef(_) => None,
            VNode::VTag(vtag) => vtag.key.as_ref(),
            VNode::VText(_) => None,
            VNode::VPortal(vportal) => vportal.node.key(),
            VNode::VSuspense(vsuspense) => vsuspense.key.as_ref(),
            VNode::VRaw(_) => None,
        }
    }

    /// Returns true if the [VNode] has a key.
    pub fn has_key(&self) -> bool {
        self.key().is_some()
    }

    /// Acquires a mutable reference of current VNode as a VList.
    ///
    /// Creates a VList with the current node as the first child if current VNode is not a VList.
    pub fn to_vlist_mut(&mut self) -> &mut VList {
        loop {
            match *self {
                Self::VList(ref mut m) => return m,
                _ => {
                    *self = VNode::VList(VList::with_children(vec![mem::take(self)], None));
                }
            }
        }
    }

    /// Create a [`VNode`] from a string of HTML
    ///
    /// # Behavior in browser
    ///
    /// In the browser, this function creates an element, sets the passed HTML to its `innerHTML`
    /// and inserts the contents of it into the DOM.
    ///
    /// # Behavior on server
    ///
    /// When rendering on the server, the contents of HTML are directly injected into the HTML
    /// stream.
    ///
    /// ## Warning
    ///
    /// The contents are **not** sanitized or validated. You, as the developer, are responsible to
    /// ensure the HTML string passed to this method are _valid_ and _not malicious_
    ///
    /// # Example
    ///
    /// ```rust
    /// use yew::{html, AttrValue, Html};
    /// # fn _main() {
    /// let parsed = Html::from_html_unchecked(AttrValue::from("<div>content</div>"));
    /// let _: Html = html! {
    ///     <div>
    ///         {parsed}
    ///     </div>
    /// };
    /// # }
    /// ```
    pub fn from_html_unchecked(html: AttrValue) -> Self {
        VNode::VRaw(VRaw { html })
    }
}

impl Default for VNode {
    fn default() -> Self {
        VNode::VList(VList::default())
    }
}

impl From<VText> for VNode {
    #[inline]
    fn from(vtext: VText) -> Self {
        VNode::VText(vtext)
    }
}

impl From<VList> for VNode {
    #[inline]
    fn from(vlist: VList) -> Self {
        VNode::VList(vlist)
    }
}

impl From<VTag> for VNode {
    #[inline]
    fn from(vtag: VTag) -> Self {
        VNode::VTag(Box::new(vtag))
    }
}

impl From<VComp> for VNode {
    #[inline]
    fn from(vcomp: VComp) -> Self {
        VNode::VComp(vcomp)
    }
}

impl From<VSuspense> for VNode {
    #[inline]
    fn from(vsuspense: VSuspense) -> Self {
        VNode::VSuspense(vsuspense)
    }
}

impl From<VPortal> for VNode {
    #[inline]
    fn from(vportal: VPortal) -> Self {
        VNode::VPortal(vportal)
    }
}

impl<COMP> From<VChild<COMP>> for VNode
where
    COMP: BaseComponent,
{
    fn from(vchild: VChild<COMP>) -> Self {
        VNode::VComp(VComp::from(vchild))
    }
}

impl<T: ToString> From<T> for VNode {
    fn from(value: T) -> Self {
        VNode::VText(VText::new(value.to_string()))
    }
}

impl<A: Into<VNode>> FromIterator<A> for VNode {
    fn from_iter<T: IntoIterator<Item = A>>(iter: T) -> Self {
        VNode::VList(VList::with_children(
            iter.into_iter().map(|n| n.into()).collect(),
            None,
        ))
    }
}

impl fmt::Debug for VNode {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match *self {
            VNode::VTag(ref vtag) => vtag.fmt(f),
            VNode::VText(ref vtext) => vtext.fmt(f),
            VNode::VComp(ref vcomp) => vcomp.fmt(f),
            VNode::VList(ref vlist) => vlist.fmt(f),
            VNode::VRef(ref vref) => write!(f, "VRef ( \"{}\" )", crate::utils::print_node(vref)),
            VNode::VPortal(ref vportal) => vportal.fmt(f),
            VNode::VSuspense(ref vsuspense) => vsuspense.fmt(f),
            VNode::VRaw(ref vraw) => write!(f, "VRaw {{ {} }}", vraw.html),
        }
    }
}

#[cfg(feature = "ssr")]
mod feat_ssr {
    use futures::future::{FutureExt, LocalBoxFuture};

    use super::*;
    use crate::feat_ssr::VTagKind;
    use crate::html::AnyScope;
    use crate::platform::fmt::BufWriter;

    impl VNode {
        pub(crate) fn render_into_stream<'a>(
            &'a self,
            w: &'a mut BufWriter,
            parent_scope: &'a AnyScope,
            hydratable: bool,
            parent_vtag_kind: VTagKind,
        ) -> LocalBoxFuture<'a, ()> {
            async fn render_into_stream_(
                this: &VNode,
                w: &mut BufWriter,
                parent_scope: &AnyScope,
                hydratable: bool,
                parent_vtag_kind: VTagKind,
            ) {
                match this {
                    VNode::VTag(vtag) => vtag.render_into_stream(w, parent_scope, hydratable).await,
                    VNode::VText(vtext) => {
                        vtext
                            .render_into_stream(w, parent_scope, hydratable, parent_vtag_kind)
                            .await
                    }
                    VNode::VComp(vcomp) => {
                        vcomp
                            .render_into_stream(w, parent_scope, hydratable, parent_vtag_kind)
                            .await
                    }
                    VNode::VList(vlist) => {
                        vlist
                            .render_into_stream(w, parent_scope, hydratable, parent_vtag_kind)
                            .await
                    }
                    // We are pretty safe here as it's not possible to get a web_sys::Node without
                    // DOM support in the first place.
                    //
                    // The only exception would be to use `ServerRenderer` in a browser or wasm32
                    // environment with jsdom present.
                    VNode::VRef(_) => {
                        panic!("VRef is not possible to be rendered in to a string.")
                    }
                    // Portals are not rendered.
                    VNode::VPortal(_) => {}
                    VNode::VSuspense(vsuspense) => {
                        vsuspense
                            .render_into_stream(w, parent_scope, hydratable, parent_vtag_kind)
                            .await
                    }

                    VNode::VRaw(vraw) => vraw.render_into_stream(w, parent_scope, hydratable).await,
                }
            }

            async move {
                render_into_stream_(self, w, parent_scope, hydratable, parent_vtag_kind).await
            }.boxed_local()
        }
    }
}