//! AWS API requests.
//!
//! Wraps the `hyper` library to send PUT, POST, DELETE and GET requests.

extern crate lazy_static;

use std::env;
use std::io::Read;
use std::io::Error as IoError;
use std::error::Error;
use std::fmt;
use std::collections::HashMap;

use hyper::Client;
use hyper::Error as HyperError;
use hyper::header::{Headers, UserAgent};
use hyper::status::StatusCode;
use hyper::method::Method;
use hyper::client::RedirectPolicy;
use hyper::net::HttpsConnector;
use hyper_native_tls::NativeTlsClient;

use log::LogLevel::Debug;

use signature::SignedRequest;

// Pulls in the statically generated rustc version.
include!(concat!(env!("OUT_DIR"), "/user_agent_vars.rs"));

// Use a lazy static to cache the default User-Agent header
// because it never changes once it's been computed.
lazy_static! {
    static ref DEFAULT_USER_AGENT: Vec<Vec<u8>> = vec![format!("rusoto/{} rust/{} {}",
            env!("CARGO_PKG_VERSION"), RUST_VERSION, env::consts::OS).as_bytes().to_vec()];
}


#[derive(Clone)]
pub struct HttpResponse {
    pub status: StatusCode,
    pub body: Vec<u8>,
    pub headers: HashMap<String, String>,
}

#[derive(Debug, PartialEq)]
pub struct HttpDispatchError {
    message: String,
}

impl Error for HttpDispatchError {
    fn description(&self) -> &str {
        &self.message
    }
}

impl fmt::Display for HttpDispatchError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.message)
    }
}

impl From<HyperError> for HttpDispatchError {
    fn from(err: HyperError) -> HttpDispatchError {
        HttpDispatchError { message: err.description().to_string() }
    }
}

impl From<IoError> for HttpDispatchError {
    fn from(err: IoError) -> HttpDispatchError {
        HttpDispatchError { message: err.description().to_string() }
    }
}

pub trait DispatchSignedRequest {
    fn dispatch(&self, request: &SignedRequest) -> Result<HttpResponse, HttpDispatchError>;
}

impl DispatchSignedRequest for Client {
    fn dispatch(&self, request: &SignedRequest) -> Result<HttpResponse, HttpDispatchError> {
        let hyper_method = match request.method().as_ref() {
            "POST" => Method::Post,
            "PUT" => Method::Put,
            "DELETE" => Method::Delete,
            "GET" => Method::Get,
            "HEAD" => Method::Head,
            v => return Err(HttpDispatchError { message: format!("Unsupported HTTP verb {}", v) }),
        };

        // translate the headers map to a format Hyper likes
        let mut hyper_headers = Headers::new();
        for h in request.headers().iter() {
            hyper_headers.set_raw(h.0.to_owned(), h.1.to_owned());
        }

        // Add a default user-agent header if one is not already present.
        if !hyper_headers.has::<UserAgent>() {
            hyper_headers.set_raw("user-agent".to_owned(), DEFAULT_USER_AGENT.clone());
        }

        let mut final_uri = format!("https://{}{}", request.hostname(), request.canonical_path());
        if !request.canonical_query_string().is_empty() {
            final_uri = final_uri + &format!("?{}", request.canonical_query_string());
        }

        if log_enabled!(Debug) {
            let payload = match request.payload {
                Some(ref payload_bytes) => {
                    String::from_utf8(payload_bytes.to_owned())
                        .unwrap_or_else(|_| String::from("<non-UTF-8 data>"))
                }
                _ => "".to_owned(),
            };

            debug!("Full request: \n method: {}\n final_uri: {}\n payload: {}\nHeaders:\n",
                   hyper_method,
                   final_uri,
                   payload);
            for h in hyper_headers.iter() {
                debug!("{}:{}", h.name(), h.value_string());
            }
        }
        let mut hyper_response = match request.payload {
            None => {
                try!(self.request(hyper_method, &final_uri).headers(hyper_headers).body("").send())
            }
            Some(ref payload_contents) => {
                try!(self.request(hyper_method, &final_uri)
                    .headers(hyper_headers)
                    .body(payload_contents.as_slice())
                    .send())
            }
        };
        let mut body: Vec<u8> = Vec::new();

        try!(hyper_response.read_to_end(&mut body));

        if log_enabled!(Debug) {
            debug!("Response body:\n{:?}", body);
        }

        let mut headers: HashMap<String, String> = HashMap::new();

        for header in hyper_response.headers.iter() {
            headers.insert(header.name().to_string(), header.value_string());
        }

        Ok(HttpResponse {
            status: hyper_response.status,
            body: body,
            headers: headers,
        })

    }
}

#[derive(Debug, PartialEq)]
pub struct TlsError {
    message: String,
}

impl Error for TlsError {
    fn description(&self) -> &str {
        &self.message
    }
}

impl fmt::Display for TlsError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.message)
    }
}

/// Helper method for creating an http client with tls.
/// Makes a `hyper` client with `NativeTls` for HTTPS support.
pub fn default_tls_client() -> Result<Client, TlsError> {
    let ssl = match NativeTlsClient::new() {
        Ok(ssl) => ssl,
        Err(tls_error) => {
            return Err(TlsError {
                message: format!("Couldn't create NativeTlsClient: {}", tls_error),
            })
        }
    };
    let connector = HttpsConnector::new(ssl);
    let mut client = Client::with_connector(connector);
    client.set_redirect_policy(RedirectPolicy::FollowNone);
    Ok(client)
}