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, PayloadStream};
use actix_web::error::{ErrorBadRequest, ErrorInternalServerError, PayloadError};
use actix_web::web::{Bytes, BytesMut};
use bytes::{Buf, BufMut};
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::routes::{get_routes, RequestResult, Route};
use crate::controllers::routes::Method::{GET, POST};
use crate::data::config::Config;
use crate::data::http_request_handler::{HttpRequestHandler, PostFile, RequestValue};

/// 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,
}

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 >= MAX_REQUEST_SIZE { // TODO : check if works
            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: web::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>>;
    type Config = ();

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

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


        async move {

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


            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().ok_or(
                        ErrorInternalServerError("Missing content type"))?;
                    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.to_bytes(),
                                         }));
                    }

                    // 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?.bytes()));
                        }

                        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
fn process_simple_route(route: &Route, req: &mut HttpRequestHandler) -> RequestResult {

    // Validate client token
    req.check_client_token()?;

    // Check user token, if required
    if route.need_login || req.has_post_parameter("userToken1") {
        req.check_user_token()?;
    }

    (route.func)(req)
}

/// Process an incoming request
async fn process_request(custom_req: CustomRequest) -> HttpResponse {
    let req = &custom_req.req;
    let routes = get_routes();

    // We search the appropriate route for the request
    let mut route: Option<&Route> = None;
    for el in &routes {

        // Check verb
        if !(req.method() == http::Method::GET && el.method == GET) &&
            !(req.method() == http::Method::POST && el.method == POST) {
            continue;
        }

        // Check path
        if !el.uri.eq(req.uri()) {
            continue;
        }

        route = Some(el);
        break;
    }

    // Check if a route was found
    if let None = route {
        return HttpResponse::NotFound().json(HttpError::not_found("Method not found!"));
    }
    let route = route.unwrap();

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

    match process_simple_route(route, &mut request) {

        // 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.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.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")
        }
    }
}


/// Given the configuration, start the server
pub async fn start_server(conf: &Config) -> std::io::Result<()> {
    let addr = conf.server_listen_address();
    println!("Start to listen on http://{}/", addr);

    HttpServer::new(|| {
        App::new()
            .route("**", web::get().to(process_request))
            .route("**", web::post().to(process_request))
    }).bind(&addr)?.run().await
}