extern crate chrono;
extern crate http;
extern crate mime_guess;
extern crate serde;

use chrono::offset::Utc;
use chrono::DateTime;

use http::status::StatusCode;
use serde::{Deserialize, Serialize};

use std::collections::HashMap;
use std::convert::TryFrom;
use std::io::{self, prelude::*};
use std::net::TcpStream;
use std::path::Path;
use std::time::{Duration, SystemTime};

use crate::http_request::HttpRequest;
use crate::http_response::HttpResponse;
use crate::server_config::ServerConfig;
use crate::server_routes_scan::ServerRoutesScan;
use crate::static_http_server_route::{ServingMode, StaticHttpServerRoute};
use crate::subdomain_info::SubdomainInfo;
use crate::text_template::{InterruptDetermination, TextTemplate, TextTemplateRenderingError};
use crate::utils::{
    content_type_for_exension_osstr, datetime_to_secs, parse_modified_since_or_epoch,
    search_for_file,
};

#[derive(Clone, Deserialize, Serialize, Debug)]
pub struct StaticHttpServer {
    pub config: ServerConfig,
    pub scan: ServerRoutesScan,
}

impl StaticHttpServer {
    pub fn new(server_config: ServerConfig) -> Self {
        let mut this = Self {
            config: server_config,
            scan: ServerRoutesScan::default(),
        };
        this.check_for_changes();
        this
    }

    pub fn check_for_changes(&mut self) {
        self.scan.check_for_changes_mut(&self.config)
    }

    pub fn handle_stream(self, mut stream: TcpStream) {
        let mut buffer: [u8; 2048] = [0; 2048];
        if stream.read(&mut buffer).unwrap_or(0) > 0 {
            match HttpRequest::try_from(buffer.as_ref()) {
                Ok(request) => {
                    if let Err(err) = self.handle_request(&request, &stream) {
                        eprintln!("Warn: Could not yield a response successfully: {:?}", err);
                    }
                }
                Err(err) => {
                    eprintln!("Warn: Could not parse request: {:?}", err);
                }
            }
        } else if let Err(err) = self.generate_404(None).send_reply(&stream) {
            eprintln!("Warn: Could print 404 for empty request: {:?}", err);
        }
        let _ = stream.shutdown(std::net::Shutdown::Both);
    }

    fn log_request(
        &self,
        system_time: &SystemTime,
        http_request: &HttpRequest,
        stream_peer_addr_str: &str,
    ) {
        let datetime: DateTime<Utc> = (*system_time).into();
        let bt = format!("{}:{}", self.config.bind, self.config.port);
        let now_formatted = datetime.format("%Y-%m-%d %T");
        println!(
            "[{}] => ... {} {} request: {}{} by {}",
            now_formatted,
            http_request.http,
            http_request.verb,
            http_request.headers.get("host").unwrap_or(&bt),
            http_request.path,
            stream_peer_addr_str,
        );
    }

    fn log_response(
        &self,
        system_time: &SystemTime,
        system_time_start: &SystemTime,
        http_request: &HttpRequest,
        response: &HttpResponse,
        stream_peer_addr_str: &str,
    ) -> io::Result<()> {
        let total_time = system_time
            .duration_since(*system_time_start)
            .map_err(|_| std::io::ErrorKind::InvalidData)?;
        let datetime: DateTime<Utc> = (*system_time).into();
        let now_formatted = datetime.format("%Y-%m-%d %T");
        let bt = format!("{}:{}", self.config.bind, self.config.port);
        println!(
            "[{}] <= {:?} {} {} request: {}{} by {}; replied {} bytes on {} microsseconds",
            now_formatted,
            response.http_code,
            http_request.http,
            http_request.verb,
            http_request.headers.get("host").unwrap_or(&bt),
            http_request.path,
            stream_peer_addr_str,
            response.payload.len(),
            total_time.as_micros(),
        );
        Ok(())
    }

    fn handle_request(
        &self,
        http_request: &HttpRequest,
        stream: &TcpStream,
    ) -> std::io::Result<()> {
        let bt = format!("{}:{}", self.config.bind, self.config.port);
        let host = http_request.headers.get("host").unwrap_or(&bt);
        let subhost = host.chars().skip_while(|c| *c != '.').collect::<String>();
        let system_time_start = SystemTime::now();
        let stream_peer_addr_str = stream
            .peer_addr()
            .map(|x| format!("{}", x))
            .unwrap_or_else(|_| "[?]".to_owned());
        if self.config.log_accesses {
            self.log_request(&system_time_start, http_request, &stream_peer_addr_str);
        }
        let response: HttpResponse = self
            .scan
            .graph
            .get(host)
            .or_else(|| self.scan.subdomains.get(&subhost))
            .and_then(|routes| {
                let mut response_: Option<HttpResponse> = None;
                for route in routes.iter() {
                    if http_request.path.starts_with(&route.prefix) {
                        response_ = Some(
                            self.get_for_route(http_request, route)
                                .with_hsts(route.hsts),
                        );
                        break;
                    }
                }
                response_
            })
            .unwrap_or_else(|| self.generate_404(None));
        if self.config.log_accesses
            || (self.config.log_redirects && response.http_code == StatusCode::FOUND)
            || (self.config.log_not_founds && response.http_code == StatusCode::NOT_FOUND)
            || (self.config.log_server_errors
                && response.http_code == StatusCode::INTERNAL_SERVER_ERROR)
        {
            if !self.config.log_accesses {
                self.log_request(&system_time_start, http_request, &stream_peer_addr_str);
            }
            let system_time = SystemTime::now();
            self.log_response(
                &system_time,
                &system_time_start,
                http_request,
                &response,
                &stream_peer_addr_str,
            )?;
        }
        response.send_reply(stream)
    }

    fn generate_404(&self, route_opt: Option<&StaticHttpServerRoute>) -> HttpResponse {
        route_opt
            .and_then(|route| route.generate_404())
            .or_else(|| self.config.generate_404())
            .unwrap_or_else(HttpResponse::generate_404)
    }

    fn get_for_route(
        &self,
        http_request: &HttpRequest,
        route: &StaticHttpServerRoute,
    ) -> HttpResponse {
        let bt = format!("{}:{}", self.config.bind, self.config.port);
        let requested_file = http_request.path[route.prefix.len()..].to_string();
        let host = http_request.headers.get("host").unwrap_or(&bt);
        let subhostroot = host.chars().skip_while(|c| *c != '.').collect::<String>();
        let subhostpart = host.chars().take_while(|c| *c != '.').collect::<String>();
        let (discriminator_folder, domain_root): (Option<&str>, &str) =
            if route.domain != *host && route.domain.ends_with(&subhostroot) {
                (Some(&subhostpart), &subhostroot)
            } else {
                (None, host)
            };
        match route.mode {
            ServingMode::Serving => search_for_file(
                &route.path,
                &requested_file,
                &self.config.try_files,
                discriminator_folder,
            )
            .filter_map(|canonical_path| {
                self.generate_file_response(
                    &canonical_path,
                    http_request.headers.get("if-modified-since"),
                )
            })
            .next(),
            ServingMode::RedirectTo => Some(HttpResponse::generate_302(&route.redirect)),
            ServingMode::RedirectKeepingRoute => Some(HttpResponse::generate_302(format!(
                "{}/{}",
                route.redirect.trim_end_matches('/'),
                requested_file.trim_start_matches('/')
            ))),
            ServingMode::RedirectKeepingRouteAndSubdomain => {
                Some(HttpResponse::generate_302(format!(
                    "https://{}.{}/{}",
                    subhostpart,
                    route.redirect,
                    requested_file.trim_start_matches('/')
                )))
            }
            ServingMode::Templating => search_for_file(
                &route.path,
                &requested_file,
                &self.config.try_files,
                discriminator_folder,
            )
            .filter_map(|canonical_path| {
                self.generate_file_response(
                    &canonical_path,
                    http_request.headers.get("if-modified-since"),
                )
            })
            .next()
            .or_else(|| {
                search_for_file(
                    &route.template_path,
                    &requested_file,
                    &self.config.try_templates,
                    discriminator_folder,
                )
                .chain(search_for_file(
                    &route.template_path,
                    "",
                    &self.config.try_templates,
                    discriminator_folder,
                ))
                .flat_map(|path_template| {
                    search_for_file(
                        &route.path,
                        &requested_file,
                        &self.config.try_data,
                        discriminator_folder,
                    )
                    .map(move |path_data| (path_template.to_owned(), path_data))
                })
                .filter_map(|(path_template, path_data)| {
                    self.generate_template_reponse(
                        &path_data,
                        &path_template,
                        http_request.headers.get("if-modified-since"),
                        &SubdomainInfo::new(
                            host,
                            &subhostroot,
                            &subhostpart,
                            domain_root,
                            discriminator_folder,
                        ),
                        route,
                        (&http_request.query_args, &http_request.headers),
                    )
                })
                .next()
            }),
        }
        .unwrap_or_else(|| self.generate_404(Some(route)))
    }

    fn get_files_max_age(paths: &[&Path]) -> Option<u64> {
        paths
            .iter()
            .map(|path| {
                path.metadata()
                    .ok()
                    .and_then(|metadata| metadata.modified().ok())
                    .and_then(|systime| systime.duration_since(SystemTime::UNIX_EPOCH).ok())
                    .map(|duration| duration.as_secs())
            })
            .reduce(|acc, x| acc.and_then(|acc1| x.map(|x1| u64::max(acc1, x1))))
            .flatten()
    }

    fn generate_file_response(
        &self,
        path: &Path,
        modified_since: Option<&String>,
    ) -> Option<HttpResponse> {
        let modified_since_parsed: DateTime<Utc> = parse_modified_since_or_epoch(modified_since);
        let browser_cache = datetime_to_secs(modified_since_parsed);
        let file_time_opt = Self::get_files_max_age(&[path]).map(|x| x as i64);
        file_time_opt.and_then(|file_time| {
            (browser_cache == file_time)
                .then(|| HttpResponse::generate_304(modified_since_parsed.into()))
                .or_else(|| {
                    std::fs::read(path).ok().map(|content| {
                        HttpResponse::new(
                            StatusCode::OK,
                            content.as_slice(),
                            content_type_for_exension_osstr(path.extension()),
                            Some(SystemTime::UNIX_EPOCH + Duration::from_secs(file_time as u64)),
                            None,
                            false,
                        )
                    })
                })
        })
    }

    fn generate_template_reponse(
        &self,
        path_data: &Path,
        path_template: &Path,
        modified_since: Option<&String>,
        subdomain: &SubdomainInfo,
        route: &StaticHttpServerRoute,
        (query, headers): (&HashMap<String, String>, &HashMap<String, String>),
    ) -> Option<HttpResponse> {
        let modified_since_parsed: DateTime<Utc> = parse_modified_since_or_epoch(modified_since);
        let browser_cache = datetime_to_secs(modified_since_parsed);
        let file_time_opt = Self::get_files_max_age(&[path_template, path_data]).map(|x| x as i64);
        path_data
            .extension()
            .and_then(|ext_osstr| ext_osstr.to_str())
            .and_then(|ext_str| self.config.datum_extension_parser.get(ext_str))
            .and_then(|p| {
                file_time_opt.and_then(|file_time| {
                    (browser_cache == file_time)
                        .then(|| HttpResponse::generate_304(modified_since_parsed.into()))
                        .or_else(|| {
                            std::fs::read(path_template)
                                .map_err(|tplerr| format!("{:?}", tplerr))
                                .and_then(|content_template| {
                                    String::from_utf8(content_template)
                                        .map_err(|tplerr| format!("{:?}", tplerr))
                                        .and_then(|string_template| {
                                            TextTemplate::try_from(string_template.as_ref())
                                                .map_err(|tplerr| format!("{:?}", tplerr))
                                        })
                                        .and_then(|tpl| {
                                            std::fs::read(path_data)
                                                .map_err(|tplerr| format!("{:?}", tplerr))
                                                .and_then(|content_data| {
                                                    String::from_utf8(content_data)
                                                        .map_err(|tplerr| format!("{:?}", tplerr))
                                                        .and_then(|string_data| {
                                                            tpl.render(subdomain, query, headers, *p, &string_data)
                                                                .map(|rnd| {
                                                                    HttpResponse::from(rnd.with_time(Some(
                                                                        SystemTime::UNIX_EPOCH
                                                                            + Duration::from_secs(file_time as u64),
                                                                    )))
                                                                })
                                                                .or_else(|err| match err {
                                                                    TextTemplateRenderingError::InterruptedRenderingWith(determination) =>{
                                                                        match determination {
                                                                            InterruptDetermination::RenderedResponse(resp) => Ok(resp),
                                                                            InterruptDetermination::Return404 => Ok(self.generate_404(Some(route))),
                                                                        }
                                                                    },
                                                                    e => Err(e),
                                                                })
                                                                .map_err(|tplerr| {
                                                                    format!("{:?}", tplerr)
                                                                })
                                                        })
                                                })
                                        })
                                })
                                .or_else(Self::string_err_to_500)
                                .ok()
                        })
                })
            })
    }

    fn string_err_to_500(err: String) -> Result<HttpResponse, String> {
        Ok::<HttpResponse, String>(HttpResponse::generate_500(Some(&err)))
    }
}