use serde::{Deserialize, Serialize};
use wasm_bindgen::prelude::*;
use wasm_bindgen::JsCast;
use wasm_bindgen_futures::JsFuture;
use web_sys::{Request, RequestInit, RequestMode, Response};

/// A struct to hold some data from the github Branch API.
///
/// Note how we don't have to define every member -- serde will ignore extra
/// data when deserializing
#[derive(Debug, Serialize, Deserialize)]
pub struct Branch {
    pub name: String,
    pub commit: Commit,
}

#[derive(Debug, Serialize, Deserialize)]
pub struct Commit {
    pub sha: String,
    pub commit: CommitDetails,
}

#[derive(Debug, Serialize, Deserialize)]
pub struct CommitDetails {
    pub author: Signature,
    pub committer: Signature,
}

#[derive(Debug, Serialize, Deserialize)]
pub struct Signature {
    pub name: String,
    pub email: String,
}

#[wasm_bindgen]
pub async fn run() -> Result<JsValue, JsValue> {
    let mut opts = RequestInit::new();
    opts.method("GET");
    opts.mode(RequestMode::Cors);

    let request = Request::new_with_str_and_init(
        "https://api.github.com/repos/rustwasm/wasm-bindgen/branches/master",
        &opts,
    )?;

    request
        .headers()
        .set("Accept", "application/vnd.github.v3+json")?;

    let window = web_sys::window().unwrap();
    let resp_value = JsFuture::from(window.fetch_with_request(&request)).await?;

    // `resp_value` is a `Response` object.
    assert!(resp_value.is_instance_of::<Response>());
    let resp: Response = resp_value.dyn_into().unwrap();

    // Convert this other `Promise` into a rust `Future`.
    let json = JsFuture::from(resp.json()?).await?;

    // Use serde to parse the JSON into a struct.
    let branch_info: Branch = json.into_serde().unwrap();

    // Send the `Branch` struct back to JS as an `Object`.
    Ok(JsValue::from_serde(&branch_info).unwrap())
}