//!
//! DOM injection utilities, allowing injection of `script` and `style`
//! elements from Rust buffers using [`Blob`](https://developer.mozilla.org/en-US/docs/Web/API/Blob)
//! objects.
//!
//! This can be used in conjunction with [`include_bytes`] macro to embed
//! JavaScript scripts, modules and CSS stylesheets directly within WASM
//! binary.
//!

use crate::result::*;
use crate::utils::*;
use js_sys::{Array, Function, Uint8Array};
use web_sys::Element;
use web_sys::{Blob, Url};
use workflow_core::channel::oneshot;
use workflow_wasm::callback::*;

pub type CustomEventCallback = Callback<CallbackClosureWithoutResult<web_sys::CustomEvent>>;

/// The Content enum specifies the type of the content being injected
/// Each enum variant contains optional content `id` and `&[u8]` data.
pub enum Content<'content> {
    /// This data slice represents a JavaScript script
    Script(Option<&'content str>, &'content [u8]),
    /// This data slice represents a JavaScript module
    Module(Option<&'content str>, &'content [u8]),
    /// This data slice represents a CSS stylesheet
    Style(Option<&'content str>, &'content [u8]),
}

/// Inject CSS stylesheed directly into DOM as a
/// [`<style>`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/style)
/// element using [`Element::set_inner_html`]
pub fn inject_css(css: &str) -> Result<()> {
    let doc = document();
    let head = doc
        .get_elements_by_tag_name("head")
        .item(0)
        .ok_or("Unable to locate head element")?;
    let style_el = doc.create_element("style")?;
    style_el.set_inner_html(css);
    head.append_child(&style_el)?;
    Ok(())
}

/// Inject a [`Blob`](https://developer.mozilla.org/en-US/docs/Web/API/Blob)
/// into DOM. The `content` argument carries the data buffer and
/// the content type represented by the [`Content`] struct.
pub fn inject_blob_nowait(content: Content) -> Result<()> {
    inject_blob_with_callback::<CustomEventCallback>(content, None)
}

/// Inject a [`Blob`](https://developer.mozilla.org/en-US/docs/Web/API/Blob)
/// into DOM. The `content` argument carries the data buffer and
/// the content type represented by the [`Content`] struct. This function
/// returns a future that completes upon injection completion.
pub async fn inject_blob(content: Content<'_>) -> Result<()> {
    let (sender, receiver) = oneshot();
    let callback = callback!(move |event: web_sys::CustomEvent| {
        sender
            .try_send(event)
            .expect("inject_blob_with_callback(): unable to send load notification");
    });
    inject_blob_with_callback(content, Some(&callback))?;
    let _notification = receiver.recv().await?;
    Ok(())
}

/// Inject script as a [`Blob`](https://developer.mozilla.org/en-US/docs/Web/API/Blob) buffer
/// into DOM. Executes an optional `load` callback when the loading is complete. The load callback
/// receives [`web_sys::CustomEvent`] struct indicating the load result.
// pub fn inject_script(root:Element, id : Option<&str>, content:&[u8], content_type:&str, callback : Option<&CustomEventCallback>) -> Result<()> {
pub fn inject_script<C>(
    root: Element,
    id: Option<&str>,
    content: &[u8],
    content_type: &str,
    callback: Option<&C>,
) -> Result<()>
where
    C: AsRef<Function>,
{
    let doc = document();
    let string = String::from_utf8_lossy(content);
    let regex = regex::Regex::new(r"//# sourceMappingURL.*$").unwrap();
    let content = regex.replace(&string, "");

    let args = Array::new_with_length(1);
    args.set(0, unsafe { Uint8Array::view(content.as_bytes()).into() });
    let mut options = web_sys::BlobPropertyBag::new();
    options.type_("application/javascript");
    let blob = Blob::new_with_u8_array_sequence_and_options(&args, &options)?;
    let url = Url::create_object_url_with_blob(&blob)?;

    let script = doc.create_element("script")?;
    if let Some(callback) = callback {
        script.add_event_listener_with_callback("load", callback.as_ref())?;
    }
    if let Some(id) = id {
        script.set_attribute("id", id)?;
    }
    script.set_attribute("type", content_type)?;
    script.set_attribute("src", &url)?;
    root.append_child(&script)?;

    Ok(())
}

pub fn inject_stylesheet<C>(
    root: Element,
    id: Option<&str>,
    content: &[u8],
    callback: Option<&C>,
) -> Result<()>
where
    C: AsRef<Function>,
{
    let args = Array::new_with_length(1);
    args.set(0, unsafe { Uint8Array::view(content).into() });
    let blob = Blob::new_with_u8_array_sequence(&args)?;
    let url = Url::create_object_url_with_blob(&blob)?;

    let style = document().create_element("link")?;
    if let Some(callback) = callback {
        style.add_event_listener_with_callback("load", callback.as_ref())?;
        // closure.forget();
    }
    if let Some(id) = id {
        style.set_attribute("id", id)?;
    }
    style.set_attribute("type", "text/css")?;
    style.set_attribute("rel", "stylesheet")?;
    style.set_attribute("href", &url)?;
    root.append_child(&style)?;
    Ok(())
}

/// Inject data buffer contained in the [`Content`] struct as a [`Blob`](https://developer.mozilla.org/en-US/docs/Web/API/Blob)
/// into DOM. Executes an optional `load` callback when the loading is complete. The load callback
/// receives [`web_sys::CustomEvent`] struct indicating the load result.
pub fn inject_blob_with_callback<C>(content: Content, callback: Option<&C>) -> Result<()>
// pub fn inject_blob_with_callback(content : Content, callback : Option<&CustomEventCallback>) -> Result<()>
where
    C: AsRef<Function>,
{
    let doc = document();
    let root = {
        let collection = doc.get_elements_by_tag_name("head");
        if collection.length() > 0 {
            collection.item(0).unwrap()
        } else {
            doc.get_elements_by_tag_name("body").item(0).unwrap()
        }
    };

    match content {
        Content::Script(id, content) => {
            inject_script(root, id, content, "text/javascript", callback)?;
        }
        Content::Module(id, content) => {
            inject_script(root, id, content, "module", callback)?;
        }
        Content::Style(id, content) => {
            inject_stylesheet(root, id, content, callback)?;
        }
    }

    Ok(())
}