// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
use crate::deno_error;
use crate::deno_error::DenoError;
use deno::ErrBox;
#[cfg(test)]
use futures::future::{loop_fn, Loop};
use futures::{future, Future, Stream};
use hyper;
use hyper::client::{Client, HttpConnector};
use hyper::header::CONTENT_TYPE;
use hyper::Uri;
use hyper_rustls;

type Connector = hyper_rustls::HttpsConnector<HttpConnector>;

lazy_static! {
  static ref CONNECTOR: Connector = {
    let num_dns_threads = 4;
    Connector::new(num_dns_threads)
  };
}

pub fn get_client() -> Client<Connector, hyper::Body> {
  // TODO use Hyper's connection pool.
  let c = CONNECTOR.clone();
  Client::builder().build(c)
}

/// Construct the next uri based on base uri and location header fragment
/// See <https://tools.ietf.org/html/rfc3986#section-4.2>
fn resolve_uri_from_location(base_uri: &Uri, location: &str) -> Uri {
  if location.starts_with("http://") || location.starts_with("https://") {
    // absolute uri
    location
      .parse::<Uri>()
      .expect("provided redirect url should be a valid url")
  } else if location.starts_with("//") {
    // "//" authority path-abempty
    format!("{}:{}", base_uri.scheme_part().unwrap().as_str(), location)
      .parse::<Uri>()
      .expect("provided redirect url should be a valid url")
  } else if location.starts_with('/') {
    // path-absolute
    let mut new_uri_parts = base_uri.clone().into_parts();
    new_uri_parts.path_and_query = Some(location.parse().unwrap());
    Uri::from_parts(new_uri_parts).unwrap()
  } else {
    // assuming path-noscheme | path-empty
    let mut new_uri_parts = base_uri.clone().into_parts();
    let base_uri_path_str = base_uri.path().to_owned();
    let segs: Vec<&str> = base_uri_path_str.rsplitn(2, '/').collect();
    new_uri_parts.path_and_query = Some(
      format!("{}/{}", segs.last().unwrap_or(&""), location)
        .parse()
        .unwrap(),
    );
    Uri::from_parts(new_uri_parts).unwrap()
  }
}

#[cfg(test)]
use crate::tokio_util;
#[cfg(test)]
/// Synchronously fetchs the given HTTP URL. Returns (content, media_type).
pub fn fetch_sync_string(
  module_name: &str,
) -> Result<(String, String), ErrBox> {
  tokio_util::block_on(fetch_string(module_name))
}

pub enum FetchOnceResult {
  // (code, maybe_content_type)
  Code(String, Option<String>),
  Redirect(http::uri::Uri),
}

/// Asynchronously fetchs the given HTTP URL one pass only.
/// If no redirect is present and no error occurs,
/// yields Code(code, maybe_content_type).
/// If redirect occurs, does not follow and
/// yields Redirect(url).
pub fn fetch_string_once(
  url: http::uri::Uri,
) -> impl Future<Item = FetchOnceResult, Error = ErrBox> {
  type FetchAttempt = (Option<String>, Option<String>, Option<FetchOnceResult>);
  let client = get_client();
  client
    .get(url.clone())
    .map_err(ErrBox::from)
    .and_then(
      move |response| -> Box<
        dyn Future<Item = FetchAttempt, Error = ErrBox> + Send,
      > {
        if response.status().is_redirection() {
          let location_string = response
            .headers()
            .get("location")
            .expect("url redirection should provide 'location' header")
            .to_str()
            .unwrap()
            .to_string();
          debug!("Redirecting to {}...", &location_string);
          let new_url = resolve_uri_from_location(&url, &location_string);
          // Boxed trait object turns out to be the savior for 2+ types yielding same results.
          return Box::new(future::ok(None).join3(
            future::ok(None),
            future::ok(Some(FetchOnceResult::Redirect(new_url))),
          ));
        } else if response.status().is_client_error()
          || response.status().is_server_error()
        {
          return Box::new(future::err(DenoError::new(
            deno_error::ErrorKind::Other,
            format!("Import '{}' failed: {}", &url, response.status()),
          ).into()));
        }
        let content_type = response
          .headers()
          .get(CONTENT_TYPE)
          .map(|content_type| content_type.to_str().unwrap().to_owned());
        let body = response
          .into_body()
          .concat2()
          .map(|body| String::from_utf8(body.to_vec()).ok())
          .map_err(ErrBox::from);
        Box::new(body.join3(future::ok(content_type), future::ok(None)))
      },
    )
    .and_then(move |(maybe_code, maybe_content_type, maybe_redirect)| {
      if let Some(redirect) = maybe_redirect {
        future::ok(redirect)
      } else {
        // maybe_code should always contain code here!
        future::ok(FetchOnceResult::Code(
          maybe_code.unwrap(),
          maybe_content_type,
        ))
      }
    })
}

#[cfg(test)]
/// Asynchronously fetchs the given HTTP URL. Returns (content, media_type).
pub fn fetch_string(
  module_name: &str,
) -> impl Future<Item = (String, String), Error = ErrBox> {
  let url = module_name.parse::<Uri>().unwrap();
  let client = get_client();
  // TODO(kevinkassimo): consider set a max redirection counter
  // to avoid bouncing between 2 or more urls
  loop_fn((client, url), |(client, url)| {
    client
      .get(url.clone())
      .map_err(ErrBox::from)
      .and_then(move |response| {
        if response.status().is_redirection() {
          let location_string = response
            .headers()
            .get("location")
            .expect("url redirection should provide 'location' header")
            .to_str()
            .unwrap()
            .to_string();
          debug!("Redirecting to {}...", &location_string);
          let new_url = resolve_uri_from_location(&url, &location_string);
          return Ok(Loop::Continue((client, new_url)));
        }
        if !response.status().is_success() {
          return Err(
            DenoError::new(
              deno_error::ErrorKind::NotFound,
              "module not found".to_string(),
            )
            .into(),
          );
        }
        Ok(Loop::Break(response))
      })
  })
  .and_then(|response| {
    let content_type = response
      .headers()
      .get(CONTENT_TYPE)
      .map(|content_type| content_type.to_str().unwrap().to_string());
    let body = response
      .into_body()
      .concat2()
      .map(|body| String::from_utf8(body.to_vec()).unwrap())
      .map_err(ErrBox::from);
    body.join(future::ok(content_type))
  })
  .and_then(|(body_string, maybe_content_type)| {
    future::ok((body_string, maybe_content_type.unwrap()))
  })
}

#[test]
fn test_fetch_sync_string() {
  // Relies on external http server. See tools/http_server.py
  tokio_util::init(|| {
    let (p, m) =
      fetch_sync_string("http://127.0.0.1:4545/package.json").unwrap();
    println!("package.json len {}", p.len());
    assert!(p.len() > 1);
    assert!(m == "application/json")
  });
}

#[test]
fn test_fetch_string() {
  // Relies on external http server. See tools/http_server.py
  tokio_util::init(|| {
    let (p, m) = fetch_string("http://127.0.0.1:4545/package.json")
      .wait()
      .unwrap();
    println!("package.json len {}", p.len());
    assert!(p.len() > 1);
    assert!(m == "application/json")
  });
}

#[test]
fn test_fetch_sync_string_with_redirect() {
  // Relies on external http server. See tools/http_server.py
  tokio_util::init(|| {
    let (p, m) =
      fetch_sync_string("http://127.0.0.1:4546/package.json").unwrap();
    println!("package.json len {}", p.len());
    assert!(p.len() > 1);
    assert!(m == "application/json")
  });
}

#[test]
fn test_resolve_uri_from_location_full_1() {
  let url = "http://deno.land".parse::<Uri>().unwrap();
  let new_uri = resolve_uri_from_location(&url, "http://golang.org");
  assert_eq!(new_uri.host().unwrap(), "golang.org");
}

#[test]
fn test_resolve_uri_from_location_full_2() {
  let url = "https://deno.land".parse::<Uri>().unwrap();
  let new_uri = resolve_uri_from_location(&url, "https://golang.org");
  assert_eq!(new_uri.host().unwrap(), "golang.org");
}

#[test]
fn test_resolve_uri_from_location_relative_1() {
  let url = "http://deno.land/x".parse::<Uri>().unwrap();
  let new_uri = resolve_uri_from_location(&url, "//rust-lang.org/en-US");
  assert_eq!(new_uri.host().unwrap(), "rust-lang.org");
  assert_eq!(new_uri.path(), "/en-US");
}

#[test]
fn test_resolve_uri_from_location_relative_2() {
  let url = "http://deno.land/x".parse::<Uri>().unwrap();
  let new_uri = resolve_uri_from_location(&url, "/y");
  assert_eq!(new_uri.host().unwrap(), "deno.land");
  assert_eq!(new_uri.path(), "/y");
}

#[test]
fn test_resolve_uri_from_location_relative_3() {
  let url = "http://deno.land/x".parse::<Uri>().unwrap();
  let new_uri = resolve_uri_from_location(&url, "z");
  assert_eq!(new_uri.host().unwrap(), "deno.land");
  assert_eq!(new_uri.path(), "/z");
}