use std::cell::{Ref, RefCell, RefMut};
use std::rc::Rc;
use std::{fmt, net};

use actix_http::http::{HeaderMap, Method, Uri, Version};
use actix_http::{Error, Extensions, HttpMessage, Message, Payload, RequestHead};
use actix_router::{Path, Url};
use futures_util::future::{ok, Ready};
use smallvec::SmallVec;

use crate::app_service::AppInitServiceState;
use crate::config::AppConfig;
use crate::error::UrlGenerationError;
use crate::extract::FromRequest;
use crate::info::ConnectionInfo;
use crate::rmap::ResourceMap;

#[derive(Clone)]
/// An HTTP Request
pub struct HttpRequest {
    /// # Panics
    /// `Rc<HttpRequestInner>` is used exclusively and NO `Weak<HttpRequestInner>`
    /// is allowed anywhere in the code. Weak pointer is purposely ignored when
    /// doing `Rc`'s ref counter check. Expect panics if this invariant is violated.
    pub(crate) inner: Rc<HttpRequestInner>,
}

pub(crate) struct HttpRequestInner {
    pub(crate) head: Message<RequestHead>,
    pub(crate) path: Path<Url>,
    pub(crate) app_data: SmallVec<[Rc<Extensions>; 4]>,
    app_state: Rc<AppInitServiceState>,
}

impl HttpRequest {
    #[inline]
    pub(crate) fn new(
        path: Path<Url>,
        head: Message<RequestHead>,
        app_state: Rc<AppInitServiceState>,
        app_data: Rc<Extensions>,
    ) -> HttpRequest {
        let mut data = SmallVec::<[Rc<Extensions>; 4]>::new();
        data.push(app_data);

        HttpRequest {
            inner: Rc::new(HttpRequestInner {
                head,
                path,
                app_state,
                app_data: data,
            }),
        }
    }
}

impl HttpRequest {
    /// This method returns reference to the request head
    #[inline]
    pub fn head(&self) -> &RequestHead {
        &self.inner.head
    }

    /// This method returns mutable reference to the request head.
    /// panics if multiple references of http request exists.
    #[inline]
    pub(crate) fn head_mut(&mut self) -> &mut RequestHead {
        &mut Rc::get_mut(&mut self.inner).unwrap().head
    }

    /// Request's uri.
    #[inline]
    pub fn uri(&self) -> &Uri {
        &self.head().uri
    }

    /// Read the Request method.
    #[inline]
    pub fn method(&self) -> &Method {
        &self.head().method
    }

    /// Read the Request Version.
    #[inline]
    pub fn version(&self) -> Version {
        self.head().version
    }

    #[inline]
    /// Returns request's headers.
    pub fn headers(&self) -> &HeaderMap {
        &self.head().headers
    }

    /// The target path of this Request.
    #[inline]
    pub fn path(&self) -> &str {
        self.head().uri.path()
    }

    /// The query string in the URL.
    ///
    /// E.g., id=10
    #[inline]
    pub fn query_string(&self) -> &str {
        if let Some(query) = self.uri().query().as_ref() {
            query
        } else {
            ""
        }
    }

    /// Get a reference to the Path parameters.
    ///
    /// Params is a container for url parameters.
    /// A variable segment is specified in the form `{identifier}`,
    /// where the identifier can be used later in a request handler to
    /// access the matched value for that segment.
    #[inline]
    pub fn match_info(&self) -> &Path<Url> {
        &self.inner.path
    }

    #[inline]
    pub(crate) fn match_info_mut(&mut self) -> &mut Path<Url> {
        &mut Rc::get_mut(&mut self.inner).unwrap().path
    }

    /// The resource definition pattern that matched the path. Useful for logging and metrics.
    ///
    /// For example, when a resource with pattern `/user/{id}/profile` is defined and a call is made
    /// to `/user/123/profile` this function would return `Some("/user/{id}/profile")`.
    ///
    /// Returns a None when no resource is fully matched, including default services.
    #[inline]
    pub fn match_pattern(&self) -> Option<String> {
        self.resource_map().match_pattern(self.path())
    }

    /// The resource name that matched the path. Useful for logging and metrics.
    ///
    /// Returns a None when no resource is fully matched, including default services.
    #[inline]
    pub fn match_name(&self) -> Option<&str> {
        self.resource_map().match_name(self.path())
    }

    /// Request extensions
    #[inline]
    pub fn extensions(&self) -> Ref<'_, Extensions> {
        self.head().extensions()
    }

    /// Mutable reference to a the request's extensions
    #[inline]
    pub fn extensions_mut(&self) -> RefMut<'_, Extensions> {
        self.head().extensions_mut()
    }

    /// Generate url for named resource
    ///
    /// ```rust
    /// # use actix_web::{web, App, HttpRequest, HttpResponse};
    /// #
    /// fn index(req: HttpRequest) -> HttpResponse {
    ///     let url = req.url_for("foo", &["1", "2", "3"]); // <- generate url for "foo" resource
    ///     HttpResponse::Ok().into()
    /// }
    ///
    /// fn main() {
    ///     let app = App::new()
    ///         .service(web::resource("/test/{one}/{two}/{three}")
    ///              .name("foo")  // <- set resource name, then it could be used in `url_for`
    ///              .route(web::get().to(|| HttpResponse::Ok()))
    ///         );
    /// }
    /// ```
    pub fn url_for<U, I>(
        &self,
        name: &str,
        elements: U,
    ) -> Result<url::Url, UrlGenerationError>
    where
        U: IntoIterator<Item = I>,
        I: AsRef<str>,
    {
        self.resource_map().url_for(&self, name, elements)
    }

    /// Generate url for named resource
    ///
    /// This method is similar to `HttpRequest::url_for()` but it can be used
    /// for urls that do not contain variable parts.
    pub fn url_for_static(&self, name: &str) -> Result<url::Url, UrlGenerationError> {
        const NO_PARAMS: [&str; 0] = [];
        self.url_for(name, &NO_PARAMS)
    }

    #[inline]
    /// Get a reference to a `ResourceMap` of current application.
    pub fn resource_map(&self) -> &ResourceMap {
        &self.app_state().rmap()
    }

    /// Peer socket address
    ///
    /// Peer address is actual socket address, if proxy is used in front of
    /// actix http server, then peer address would be address of this proxy.
    ///
    /// To get client connection information `.connection_info()` should be used.
    #[inline]
    pub fn peer_addr(&self) -> Option<net::SocketAddr> {
        self.head().peer_addr
    }

    /// Get *ConnectionInfo* for the current request.
    ///
    /// This method panics if request's extensions container is already
    /// borrowed.
    #[inline]
    pub fn connection_info(&self) -> Ref<'_, ConnectionInfo> {
        ConnectionInfo::get(self.head(), self.app_config())
    }

    /// App config
    #[inline]
    pub fn app_config(&self) -> &AppConfig {
        self.app_state().config()
    }

    /// Get an application data object stored with `App::data` or `App::app_data`
    /// methods during application configuration.
    ///
    /// If `App::data` was used to store object, use `Data<T>`:
    ///
    /// ```rust,ignore
    /// let opt_t = req.app_data::<Data<T>>();
    /// ```
    pub fn app_data<T: 'static>(&self) -> Option<&T> {
        for container in self.inner.app_data.iter().rev() {
            if let Some(data) = container.get::<T>() {
                return Some(data);
            }
        }

        None
    }

    #[inline]
    fn app_state(&self) -> &AppInitServiceState {
        &*self.inner.app_state
    }
}

impl HttpMessage for HttpRequest {
    type Stream = ();

    #[inline]
    /// Returns Request's headers.
    fn headers(&self) -> &HeaderMap {
        &self.head().headers
    }

    /// Request extensions
    #[inline]
    fn extensions(&self) -> Ref<'_, Extensions> {
        self.inner.head.extensions()
    }

    /// Mutable reference to a the request's extensions
    #[inline]
    fn extensions_mut(&self) -> RefMut<'_, Extensions> {
        self.inner.head.extensions_mut()
    }

    #[inline]
    fn take_payload(&mut self) -> Payload<Self::Stream> {
        Payload::None
    }
}

impl Drop for HttpRequest {
    fn drop(&mut self) {
        // if possible, contribute to current worker's HttpRequest allocation pool

        // This relies on no Weak<HttpRequestInner> exists anywhere.(There is none)
        if let Some(inner) = Rc::get_mut(&mut self.inner) {
            if inner.app_state.pool().is_available() {
                // clear additional app_data and keep the root one for reuse.
                inner.app_data.truncate(1);
                // inner is borrowed mut here. get head's Extension mutably
                // to reduce borrow check
                inner.head.extensions.get_mut().clear();

                // a re-borrow of pool is necessary here.
                let req = self.inner.clone();
                self.app_state().pool().push(req);
            }
        }
    }
}

/// It is possible to get `HttpRequest` as an extractor handler parameter
///
/// ## Example
///
/// ```rust
/// use actix_web::{web, App, HttpRequest};
/// use serde_derive::Deserialize;
///
/// /// extract `Thing` from request
/// async fn index(req: HttpRequest) -> String {
///    format!("Got thing: {:?}", req)
/// }
///
/// fn main() {
///     let app = App::new().service(
///         web::resource("/users/{first}").route(
///             web::get().to(index))
///     );
/// }
/// ```
impl FromRequest for HttpRequest {
    type Config = ();
    type Error = Error;
    type Future = Ready<Result<Self, Error>>;

    #[inline]
    fn from_request(req: &HttpRequest, _: &mut Payload) -> Self::Future {
        ok(req.clone())
    }
}

impl fmt::Debug for HttpRequest {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        writeln!(
            f,
            "\nHttpRequest {:?} {}:{}",
            self.inner.head.version,
            self.inner.head.method,
            self.path()
        )?;
        if !self.query_string().is_empty() {
            writeln!(f, "  query: ?{:?}", self.query_string())?;
        }
        if !self.match_info().is_empty() {
            writeln!(f, "  params: {:?}", self.match_info())?;
        }
        writeln!(f, "  headers:")?;
        for (key, val) in self.headers().iter() {
            writeln!(f, "    {:?}: {:?}", key, val)?;
        }
        Ok(())
    }
}

/// Slab-allocated `HttpRequest` Pool
///
/// Since request processing may yield for asynchronous events to complete, a worker may have many
/// requests in-flight at any time. Pooling requests like this amortizes the performance and memory
/// costs of allocating and de-allocating HttpRequest objects as frequently as they otherwise would.
///
/// Request objects are added when they are dropped (see `<HttpRequest as Drop>::drop`) and re-used
/// in `<AppInitService as Service>::call` when there are available objects in the list.
///
/// The pool's default capacity is 128 items.
pub(crate) struct HttpRequestPool {
    inner: RefCell<Vec<Rc<HttpRequestInner>>>,
    cap: usize,
}

impl Default for HttpRequestPool {
    fn default() -> Self {
        Self::with_capacity(128)
    }
}

impl HttpRequestPool {
    pub(crate) fn with_capacity(cap: usize) -> Self {
        HttpRequestPool {
            inner: RefCell::new(Vec::with_capacity(cap)),
            cap,
        }
    }

    /// Re-use a previously allocated (but now completed/discarded) HttpRequest object.
    #[inline]
    pub(crate) fn pop(&self) -> Option<HttpRequest> {
        self.inner
            .borrow_mut()
            .pop()
            .map(|inner| HttpRequest { inner })
    }

    /// Check if the pool still has capacity for request storage.
    #[inline]
    pub(crate) fn is_available(&self) -> bool {
        self.inner.borrow_mut().len() < self.cap
    }

    /// Push a request to pool.
    #[inline]
    pub(crate) fn push(&self, req: Rc<HttpRequestInner>) {
        self.inner.borrow_mut().push(req);
    }

    /// Clears all allocated HttpRequest objects.
    pub(crate) fn clear(&self) {
        self.inner.borrow_mut().clear()
    }
}

#[cfg(test)]
mod tests {
    use actix_service::Service;
    use bytes::Bytes;

    use super::*;
    use crate::dev::{ResourceDef, ResourceMap};
    use crate::http::{header, StatusCode};
    use crate::test::{call_service, init_service, read_body, TestRequest};
    use crate::{web, App, HttpResponse};

    #[test]
    fn test_debug() {
        let req =
            TestRequest::with_header("content-type", "text/plain").to_http_request();
        let dbg = format!("{:?}", req);
        assert!(dbg.contains("HttpRequest"));
    }

    #[test]
    fn test_no_request_cookies() {
        let req = TestRequest::default().to_http_request();
        assert!(req.cookies().unwrap().is_empty());
    }

    #[test]
    fn test_request_cookies() {
        let req = TestRequest::default()
            .header(header::COOKIE, "cookie1=value1")
            .header(header::COOKIE, "cookie2=value2")
            .to_http_request();
        {
            let cookies = req.cookies().unwrap();
            assert_eq!(cookies.len(), 2);
            assert_eq!(cookies[0].name(), "cookie2");
            assert_eq!(cookies[0].value(), "value2");
            assert_eq!(cookies[1].name(), "cookie1");
            assert_eq!(cookies[1].value(), "value1");
        }

        let cookie = req.cookie("cookie1");
        assert!(cookie.is_some());
        let cookie = cookie.unwrap();
        assert_eq!(cookie.name(), "cookie1");
        assert_eq!(cookie.value(), "value1");

        let cookie = req.cookie("cookie-unknown");
        assert!(cookie.is_none());
    }

    #[test]
    fn test_request_query() {
        let req = TestRequest::with_uri("/?id=test").to_http_request();
        assert_eq!(req.query_string(), "id=test");
    }

    #[test]
    fn test_url_for() {
        let mut res = ResourceDef::new("/user/{name}.{ext}");
        *res.name_mut() = "index".to_string();

        let mut rmap = ResourceMap::new(ResourceDef::new(""));
        rmap.add(&mut res, None);
        assert!(rmap.has_resource("/user/test.html"));
        assert!(!rmap.has_resource("/test/unknown"));

        let req = TestRequest::with_header(header::HOST, "www.rust-lang.org")
            .rmap(rmap)
            .to_http_request();

        assert_eq!(
            req.url_for("unknown", &["test"]),
            Err(UrlGenerationError::ResourceNotFound)
        );
        assert_eq!(
            req.url_for("index", &["test"]),
            Err(UrlGenerationError::NotEnoughElements)
        );
        let url = req.url_for("index", &["test", "html"]);
        assert_eq!(
            url.ok().unwrap().as_str(),
            "http://www.rust-lang.org/user/test.html"
        );
    }

    #[test]
    fn test_url_for_static() {
        let mut rdef = ResourceDef::new("/index.html");
        *rdef.name_mut() = "index".to_string();

        let mut rmap = ResourceMap::new(ResourceDef::new(""));
        rmap.add(&mut rdef, None);

        assert!(rmap.has_resource("/index.html"));

        let req = TestRequest::with_uri("/test")
            .header(header::HOST, "www.rust-lang.org")
            .rmap(rmap)
            .to_http_request();
        let url = req.url_for_static("index");
        assert_eq!(
            url.ok().unwrap().as_str(),
            "http://www.rust-lang.org/index.html"
        );
    }

    #[test]
    fn test_match_name() {
        let mut rdef = ResourceDef::new("/index.html");
        *rdef.name_mut() = "index".to_string();

        let mut rmap = ResourceMap::new(ResourceDef::new(""));
        rmap.add(&mut rdef, None);

        assert!(rmap.has_resource("/index.html"));

        let req = TestRequest::default()
            .uri("/index.html")
            .rmap(rmap)
            .to_http_request();

        assert_eq!(req.match_name(), Some("index"));
    }

    #[test]
    fn test_url_for_external() {
        let mut rdef = ResourceDef::new("https://youtube.com/watch/{video_id}");

        *rdef.name_mut() = "youtube".to_string();

        let mut rmap = ResourceMap::new(ResourceDef::new(""));
        rmap.add(&mut rdef, None);
        assert!(rmap.has_resource("https://youtube.com/watch/unknown"));

        let req = TestRequest::default().rmap(rmap).to_http_request();
        let url = req.url_for("youtube", &["oHg5SJYRHA0"]);
        assert_eq!(
            url.ok().unwrap().as_str(),
            "https://youtube.com/watch/oHg5SJYRHA0"
        );
    }

    #[actix_rt::test]
    async fn test_drop_http_request_pool() {
        let mut srv = init_service(App::new().service(web::resource("/").to(
            |req: HttpRequest| {
                HttpResponse::Ok()
                    .set_header("pool_cap", req.app_state().pool().cap)
                    .finish()
            },
        )))
        .await;

        let req = TestRequest::default().to_request();
        let resp = call_service(&mut srv, req).await;

        drop(srv);

        assert_eq!(resp.headers().get("pool_cap").unwrap(), "128");
    }

    #[actix_rt::test]
    async fn test_data() {
        let mut srv = init_service(App::new().app_data(10usize).service(
            web::resource("/").to(|req: HttpRequest| {
                if req.app_data::<usize>().is_some() {
                    HttpResponse::Ok()
                } else {
                    HttpResponse::BadRequest()
                }
            }),
        ))
        .await;

        let req = TestRequest::default().to_request();
        let resp = call_service(&mut srv, req).await;
        assert_eq!(resp.status(), StatusCode::OK);

        let mut srv = init_service(App::new().app_data(10u32).service(
            web::resource("/").to(|req: HttpRequest| {
                if req.app_data::<usize>().is_some() {
                    HttpResponse::Ok()
                } else {
                    HttpResponse::BadRequest()
                }
            }),
        ))
        .await;

        let req = TestRequest::default().to_request();
        let resp = call_service(&mut srv, req).await;
        assert_eq!(resp.status(), StatusCode::BAD_REQUEST);
    }

    #[actix_rt::test]
    async fn test_cascading_data() {
        #[allow(dead_code)]
        fn echo_usize(req: HttpRequest) -> HttpResponse {
            let num = req.app_data::<usize>().unwrap();
            HttpResponse::Ok().body(num.to_string())
        }

        let mut srv = init_service(
            App::new()
                .app_data(88usize)
                .service(web::resource("/").route(web::get().to(echo_usize)))
                .service(
                    web::resource("/one")
                        .app_data(1u32)
                        .route(web::get().to(echo_usize)),
                ),
        )
        .await;

        let req = TestRequest::get().uri("/").to_request();
        let resp = srv.call(req).await.unwrap();
        let body = read_body(resp).await;
        assert_eq!(body, Bytes::from_static(b"88"));

        let req = TestRequest::get().uri("/one").to_request();
        let resp = srv.call(req).await.unwrap();
        let body = read_body(resp).await;
        assert_eq!(body, Bytes::from_static(b"88"));
    }

    #[actix_rt::test]
    async fn test_overwrite_data() {
        #[allow(dead_code)]
        fn echo_usize(req: HttpRequest) -> HttpResponse {
            let num = req.app_data::<usize>().unwrap();
            HttpResponse::Ok().body(num.to_string())
        }

        let mut srv = init_service(
            App::new()
                .app_data(88usize)
                .service(web::resource("/").route(web::get().to(echo_usize)))
                .service(
                    web::resource("/one")
                        .app_data(1usize)
                        .route(web::get().to(echo_usize)),
                ),
        )
        .await;

        let req = TestRequest::get().uri("/").to_request();
        let resp = srv.call(req).await.unwrap();
        let body = read_body(resp).await;
        assert_eq!(body, Bytes::from_static(b"88"));

        let req = TestRequest::get().uri("/one").to_request();
        let resp = srv.call(req).await.unwrap();
        let body = read_body(resp).await;
        assert_eq!(body, Bytes::from_static(b"1"));
    }

    #[actix_rt::test]
    async fn test_extensions_dropped() {
        struct Tracker {
            pub dropped: bool,
        }
        struct Foo {
            tracker: Rc<RefCell<Tracker>>,
        }
        impl Drop for Foo {
            fn drop(&mut self) {
                self.tracker.borrow_mut().dropped = true;
            }
        }

        let tracker = Rc::new(RefCell::new(Tracker { dropped: false }));
        {
            let tracker2 = Rc::clone(&tracker);
            let mut srv = init_service(App::new().data(10u32).service(
                web::resource("/").to(move |req: HttpRequest| {
                    req.extensions_mut().insert(Foo {
                        tracker: Rc::clone(&tracker2),
                    });
                    HttpResponse::Ok()
                }),
            ))
            .await;

            let req = TestRequest::default().to_request();
            let resp = call_service(&mut srv, req).await;
            assert_eq!(resp.status(), StatusCode::OK);
        }

        assert!(tracker.borrow().dropped);
    }

    #[actix_rt::test]
    async fn extract_path_pattern() {
        let mut srv = init_service(
            App::new().service(
                web::scope("/user/{id}")
                    .service(web::resource("/profile").route(web::get().to(
                        move |req: HttpRequest| {
                            assert_eq!(
                                req.match_pattern(),
                                Some("/user/{id}/profile".to_owned())
                            );

                            HttpResponse::Ok().finish()
                        },
                    )))
                    .default_service(web::to(move |req: HttpRequest| {
                        assert!(req.match_pattern().is_none());
                        HttpResponse::Ok().finish()
                    })),
            ),
        )
        .await;

        let req = TestRequest::get().uri("/user/22/profile").to_request();
        let res = call_service(&mut srv, req).await;
        assert_eq!(res.status(), StatusCode::OK);

        let req = TestRequest::get().uri("/user/22/not-exist").to_request();
        let res = call_service(&mut srv, req).await;
        assert_eq!(res.status(), StatusCode::OK);
    }

    #[actix_rt::test]
    async fn extract_path_pattern_complex() {
        let mut srv = init_service(
            App::new()
                .service(web::scope("/user").service(web::scope("/{id}").service(
                    web::resource("").to(move |req: HttpRequest| {
                        assert_eq!(req.match_pattern(), Some("/user/{id}".to_owned()));

                        HttpResponse::Ok().finish()
                    }),
                )))
                .service(web::resource("/").to(move |req: HttpRequest| {
                    assert_eq!(req.match_pattern(), Some("/".to_owned()));

                    HttpResponse::Ok().finish()
                }))
                .default_service(web::to(move |req: HttpRequest| {
                    assert!(req.match_pattern().is_none());
                    HttpResponse::Ok().finish()
                })),
        )
        .await;

        let req = TestRequest::get().uri("/user/test").to_request();
        let res = call_service(&mut srv, req).await;
        assert_eq!(res.status(), StatusCode::OK);

        let req = TestRequest::get().uri("/").to_request();
        let res = call_service(&mut srv, req).await;
        assert_eq!(res.status(), StatusCode::OK);

        let req = TestRequest::get().uri("/not-exist").to_request();
        let res = call_service(&mut srv, req).await;
        assert_eq!(res.status(), StatusCode::OK);
    }
}