use std::collections::HashMap;
use std::pin::Pin;

use actix_web::{App, FromRequest, http, HttpMessage, HttpRequest, HttpResponse, HttpServer, web};
use actix_web::dev::{Decompress, Payload};
use actix_web::error::{ErrorBadRequest, ErrorInternalServerError, PayloadError};
use actix_web::web::{BufMut, Bytes, BytesMut};
use encoding_rs::UTF_8;
use futures::{FutureExt, Stream, StreamExt};
use futures::future::LocalBoxFuture;
use futures::task::{Context, Poll};
use percent_encoding::percent_decode_str;

use crate::api_data::http_error::HttpError;
use crate::constants::MAX_REQUEST_SIZE;
use crate::controllers::{rtc_relay_controller, user_ws_controller};
use crate::data::base_request_handler::{BaseRequestHandler, PostFile, RequestValue};
use crate::data::config::Config;
use crate::data::http_request_handler::HttpRequestHandler;
use crate::helpers::{admin_access_token_helper, admin_key_authentication_challenges_helper, admin_key_registration_challenges_helper, api_helper, requests_limit_helper};
use crate::routes::{find_route, RequestResult, Route, RouteScope};
use crate::routes::Method::{GET, POST};
use crate::utils::user_data_utils::user_data_path;

/// Main server functions
///
/// @author Pierre Hubert

/// Custom stream to give a limit to requests size
struct LimitedStream {
    stream: Box<dyn Stream<Item=Result<Bytes, PayloadError>> + Unpin + 'static>,
    already_read: usize,
    max_size: usize,
}

impl<'a> Stream for LimitedStream
{
    type Item = Result<Bytes, PayloadError>;

    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
        if self.already_read >= self.max_size {
            return Poll::Ready(None);
        }

        let res = Pin::new(self.stream.as_mut()).poll_next(cx);

        if let Poll::Ready(Some(Ok(d))) = &res {
            self.already_read = self.already_read + d.len();
        }

        res
    }
}

/// Custom request value
struct CustomRequest {
    req: HttpRequest,
    body: HashMap<String, RequestValue>,
}

/// Process in our way incoming requests
impl FromRequest for CustomRequest {
    type Error = actix_web::Error;
    type Future = LocalBoxFuture<'static, Result<CustomRequest, actix_web::Error>>;

    fn from_request(req: &HttpRequest, payload: &mut Payload) -> Self::Future {
        let req = req.clone();
        let payload = Box::new(payload.take());

        async move {
            let content_length_size;

            // Check the size, if provided
            if req.headers().contains_key("Content-Length") {
                if let Some(v) = req.headers().get("Content-Length") {
                    content_length_size = String::from_utf8_lossy(v.as_bytes()).parse::<usize>().unwrap_or(0);
                    if content_length_size > MAX_REQUEST_SIZE {
                        return Err(actix_web::error::ErrorBadRequest("Request too big!"));
                    }
                } else {
                    unreachable!();
                }
            } else {
                return Err(actix_web::error::ErrorBadRequest("Content-Length header is required!"));
            }

            let payload = LimitedStream {
                stream: payload,
                already_read: 0,
                max_size: content_length_size,
            };


            let mut body_args = HashMap::new();

            // Process "application/x-www-form-urlencoded" requests
            if req.content_type().eq("application/x-www-form-urlencoded") {

                // Maximum size of the request
                let limit = 16384;

                // Ready body
                let mut body = BytesMut::with_capacity(8192);
                let mut stream = Decompress::from_headers(payload, req.headers());
                while let Some(item) = stream.next().await {
                    let chunk = item?;


                    if body.len() + chunk.len() > limit {
                        return Err(actix_web::error::ErrorBadRequest("Overflow - too long"));
                    } else {
                        body.extend_from_slice(&chunk);
                    }
                }
                let body = body.freeze();


                // Decode body as a string
                let encoding = req.encoding()?;

                let body_str = if encoding == UTF_8 {
                    String::from_utf8_lossy(body.as_ref()).to_string()
                } else {
                    encoding
                        .decode_without_bom_handling_and_without_replacement(&body)
                        .map(|s| s.into_owned())
                        .ok_or_else(|| ErrorBadRequest("Can not decode body"))?
                };

                // Parse body arguments (following the pattern key1=value1&key2=value2)
                if body_str.len() > 0 {
                    for v in body_str.split("&") {
                        if v.len() == 0 {
                            continue;
                        }

                        let args: Vec<&str> = v.split("=").collect();

                        if args.len() != 2 {
                            return Err(actix_web::error::ErrorBadRequest(format!("{} is invalid!", args[0])));
                        }

                        // Add the value to the body
                        body_args.insert(
                            percent_decode_str(args[0]).decode_utf8_lossy().to_string(),
                            RequestValue::String(percent_decode_str(args[1]).decode_utf8_lossy().to_string()),
                        );
                    }
                }
            }


            // Process "multipart/form-data" request
            else if req.content_type().starts_with("multipart/form-data") {
                let mut req = actix_multipart::Multipart::new(req.headers(), payload);

                // Process the list of arguments
                while let Some(el) = req.next().await {
                    let mut field = el?;

                    let content_type = field.content_disposition().clone();
                    let name = content_type.get_name().ok_or(
                        ErrorInternalServerError("Missing field name!"))?;

                    // Handle file upload
                    if content_type.get_filename().is_some() {
                        let filename = content_type.get_filename().unwrap();
                        let mut buf = BytesMut::new();

                        while let Some(chunk) = field.next().await {
                            let data = chunk.unwrap();
                            buf.put(data);
                        }

                        body_args.insert(name.to_string(),
                                         RequestValue::File(PostFile {
                                             name: filename.to_string(),
                                             buff: buf.freeze(),
                                         }));
                    }

                    // It is a simple field
                    else {
                        let mut content = String::new();

                        // Get content
                        while let Some(chunk) = field.next().await {
                            content = format!("{}{}", content, String::from_utf8_lossy(chunk?.as_ref()));
                        }

                        body_args.insert(name.to_string(), RequestValue::String(content));
                    }
                }
            }

            Ok(CustomRequest {
                req: req.clone(),
                body: body_args,
            })
        }.boxed_local()
    }
}

/// Process a "simple request" aka not a WebSocket request
async fn process_simple_route(route: &Route, req: &mut HttpRequestHandler) -> RequestResult {
    if requests_limit_helper::trigger_before(req, route).is_err() {
        req.too_many_requests("Too many request. Please try again later.")?;
    }

    // Check if the user is allowed to access the route
    match route.scope {

        // "Normal" user route
        RouteScope::USER => {
            // Validate client token
            req.check_client_token()?;

            // Check user token, if required
            if route.need_login || req.has_post_parameter("token") {
                req.check_user_token()?;
            }
        }

        // "Admin" user scope
        RouteScope::ADMIN => {
            req.check_admin_origin()?;

            if route.need_login {
                req.check_admin_access_token()?;
            }

            if let Some(role) = route.admin_role {
                req.check_admin_has_role(role)?;
            }
        }
    }


    let (_, res) = find_route(route.uri, Some(req)).await;
    let res = res.unwrap();

    requests_limit_helper::trigger_after(res.is_ok(), req, route)?;

    res
}

/// Process an incoming request
async fn process_request(custom_req: CustomRequest) -> HttpResponse {
    let req = &custom_req.req;
    let (route, _) = find_route(&req.uri().to_string(), None).await;

    // Check if a route was found with the right verb
    if !route.as_ref().map(|r|
        (req.method() == http::Method::GET && r.method == GET) ||
            (req.method() == http::Method::POST && r.method == POST)
    ).unwrap_or(false) {
        return HttpResponse::NotFound().json(HttpError::not_found("Route not found!"));
    }

    let route = route.unwrap();

    // Clean requests limit
    requests_limit_helper::clean_cache().unwrap();

    // Execute the request
    let mut request = HttpRequestHandler::new(custom_req.req, custom_req.body);

    match process_simple_route(&route, &mut request).await {

        // Set default error response if required
        Err(e) => {
            let err_msg = e.to_string();

            if !request.has_response() {
                request.internal_error(e).unwrap_err();
            }

            println!("{} - {} - {} - {}",
                     request.remote_ip(),
                     request.response_status_code(),
                     request.request_path(),
                     err_msg
            );
        }

        // Set default success response if required
        Ok(_) => {
            if !request.has_response() {
                request.success("Success").unwrap()
            }

            println!("{} - {} - {}",
                     request.remote_ip(),
                     request.response_status_code(),
                     request.request_path()
            );
        }
    }

    // Send the response
    match request.response() {
        Ok(s) => s,
        Err(e) => {
            println!("Error while getting response: {}", e);
            HttpResponse::InternalServerError().body("Response error")
        }
    }
}

/// Handle pre-flight requests
async fn handle_options_request(r: HttpRequest) -> HttpResponse {

    // Extract origin
    let origin = r.headers().get("Origin");
    if origin.is_none() {
        return HttpResponse::BadRequest().body("Missing origin header!");
    }
    let origin = origin.unwrap().to_str().unwrap_or("").to_string();

    // Find client
    let client = api_helper::get_by_origin(&origin);
    if client.is_err() {
        eprintln!("Failed to handle OPTIONS request: {:#?}", client);
        return HttpResponse::Unauthorized().body("Unkown origin!");
    }

    // Accept request
    HttpResponse::NoContent()
        .append_header(("Access-Control-Allow-Origin", origin))
        .append_header(("Access-Control-Allow-Methods", "POST, GET, OPTIONS"))
        .finish()
}


/// Given the configuration, start the server
pub fn start_server(conf: &Config) -> std::io::Result<()> {
    let sys = actix::System::new();

    // Initialize limit helper
    requests_limit_helper::init();
    admin_access_token_helper::init();
    admin_key_registration_challenges_helper::init();
    admin_key_authentication_challenges_helper::init();

    let addr = conf.server_listen_address();
    println!("Start to listen on http://{}/", addr);

    let serve_storage_file = conf.serve_storage_file;

    let server = HttpServer::new(move || {
        let mut app = App::new();

        if serve_storage_file {
            app = app.service(actix_files::Files::new("/user_data", user_data_path("".as_ref())));
        }

        // User WebSocket route
        app.service(actix_web::web::resource("/ws").to(user_ws_controller::ws_route))

            // RTC Relay WebSocket route
            .service(actix_web::web::resource("/rtc_proxy/ws").to(rtc_relay_controller::open_ws))

            // Option
            .route("{tail:.*}", web::method(http::Method::OPTIONS).to(handle_options_request))

            // API routes
            .route("{tail:.*}", web::get().to(process_request))
            .route("{tail:.*}", web::post().to(process_request))
    }).bind(&addr)?.run();

    sys.block_on(server)?;

    Ok(())
}