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

use base64::{alphabet, Engine};
use base64::engine::general_purpose::NO_PAD;
use base64::engine::GeneralPurpose;

use futures;
use futures::Future;
use futures::future::*;
use hyper;
use hyper::header::{AUTHORIZATION, CONTENT_LENGTH, CONTENT_TYPE, HeaderValue, USER_AGENT};
use serde;
use serde_json;

use super::{configuration, Error};

const MIME_ENCODER: GeneralPurpose = GeneralPurpose::new(&alphabet::STANDARD, NO_PAD);

pub(crate) struct ApiKey {
    pub in_header: bool,
    pub in_query: bool,
    pub param_name: String,
}

impl ApiKey {
    fn key(&self, prefix: &Option<String>, key: &str) -> String {
        match prefix {
            None => key.to_owned(),
            Some(ref prefix) => format!("{} {}", prefix, key),
        }
    }
}

#[allow(dead_code)]
pub(crate) enum Auth {
    None,
    ApiKey(ApiKey),
    Basic,
    Oauth,
}

/// If the authorization type is unspecified then it will be automatically detected based
/// on the configuration. This functionality is useful when the OpenAPI definition does not
/// include an authorization scheme.
pub(crate) struct Request {
    auth: Option<Auth>,
    method: hyper::Method,
    path: String,
    query_params: HashMap<String, String>,
    no_return_type: bool,
    path_params: HashMap<String, String>,
    form_params: HashMap<String, String>,
    header_params: HashMap<String, String>,
    // TODO: multiple body params are possible technically, but not supported here.
    serialized_body: Option<String>,
}

#[allow(dead_code)]
impl Request {
    pub fn new(method: hyper::Method, path: String) -> Self {
        Request {
            auth: None,
            method,
            path,
            query_params: HashMap::new(),
            path_params: HashMap::new(),
            form_params: HashMap::new(),
            header_params: HashMap::new(),
            serialized_body: None,
            no_return_type: false,
        }
    }

    pub fn with_body_param<T: serde::Serialize>(mut self, param: T) -> Self {
        self.serialized_body = Some(serde_json::to_string(&param).unwrap());
        self
    }

    pub fn with_header_param(mut self, basename: String, param: String) -> Self {
        self.header_params.insert(basename, param);
        self
    }

    #[allow(unused)]
    pub fn with_query_param(mut self, basename: String, param: String) -> Self {
        self.query_params.insert(basename, param);
        self
    }

    #[allow(unused)]
    pub fn with_path_param(mut self, basename: String, param: String) -> Self {
        self.path_params.insert(basename, param);
        self
    }

    #[allow(unused)]
    pub fn with_form_param(mut self, basename: String, param: String) -> Self {
        self.form_params.insert(basename, param);
        self
    }

    pub fn returns_nothing(mut self) -> Self {
        self.no_return_type = true;
        self
    }

    pub fn with_auth(mut self, auth: Auth) -> Self {
        self.auth = Some(auth);
        self
    }

    pub fn execute<'a, C, U>(
        self,
        conf: &configuration::Configuration<C>,
    ) -> Pin<Box<dyn Future<Output=Result<U, Error>> + 'a>>
        where
            C: hyper::client::connect::Connect + Clone + std::marker::Send + Sync,
            U: Sized + std::marker::Send + 'a,
            for<'de> U: serde::Deserialize<'de>,
    {
        let mut query_string = ::url::form_urlencoded::Serializer::new("".to_owned());

        let mut path = self.path;
        for (k, v) in self.path_params {
            // replace {id} with the value of the id path param
            path = path.replace(&format!("{{{}}}", k), &v);
        }

        for (key, val) in self.query_params {
            query_string.append_pair(&key, &val);
        }

        let mut uri_str = format!("{}{}", conf.base_path, path);

        let query_string_str = query_string.finish();
        if query_string_str != "" {
            uri_str += "?";
            uri_str += &query_string_str;
        }
        let uri: hyper::Uri = match uri_str.parse() {
            Err(e) => return Box::pin(futures::future::err(Error::UriError(e))),
            Ok(u) => u,
        };

        let mut req_builder = hyper::Request::builder()
            .uri(uri)
            .method(self.method);

        // Detect the authorization type if it hasn't been set.
        let auth = self.auth.unwrap_or_else(||
            if conf.api_key.is_some() {
                panic!("Cannot automatically set the API key from the configuration, it must be specified in the OpenAPI definition")
            } else if conf.oauth_access_token.is_some() {
                Auth::Oauth
            } else if conf.basic_auth.is_some() {
                Auth::Basic
            } else {
                Auth::None
            }
        );
        match auth {
            Auth::ApiKey(apikey) => {
                if let Some(ref key) = conf.api_key {
                    let val = apikey.key(&key.prefix, &key.key);
                    if apikey.in_query {
                        query_string.append_pair(&apikey.param_name, &val);
                    }
                    if apikey.in_header {
                        req_builder = req_builder.header(&apikey.param_name, val);
                    }
                }
            }
            Auth::Basic => {
                if let Some(ref auth_conf) = conf.basic_auth {
                    let mut text = auth_conf.0.clone();
                    text.push(':');
                    if let Some(ref pass) = auth_conf.1 {
                        text.push_str(&pass[..]);
                    }
                    let encoded = MIME_ENCODER.encode(&text);
                    req_builder = req_builder.header(AUTHORIZATION, encoded);
                }
            }
            Auth::Oauth => {
                if let Some(ref token) = conf.oauth_access_token {
                    let text = "Bearer ".to_owned() + token;
                    req_builder = req_builder.header(AUTHORIZATION, text);
                }
            }
            Auth::None => {}
        }

        if let Some(ref user_agent) = conf.user_agent {
            req_builder = req_builder.header(USER_AGENT, match HeaderValue::from_str(user_agent) {
                Ok(header_value) => header_value,
                Err(e) => return Box::pin(futures::future::err(super::Error::Header(e)))
            });
        }

        for (k, v) in self.header_params {
            req_builder = req_builder.header(&k, v);
        }

        let req_headers = req_builder.headers_mut().unwrap();
        let request_result = if self.form_params.len() > 0 {
            req_headers.insert(CONTENT_TYPE, HeaderValue::from_static("application/x-www-form-urlencoded"));
            let mut enc = ::url::form_urlencoded::Serializer::new("".to_owned());
            for (k, v) in self.form_params {
                enc.append_pair(&k, &v);
            }
            req_builder.body(hyper::Body::from(enc.finish()))
        } else if let Some(body) = self.serialized_body {
            req_headers.insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));
            req_headers.insert(CONTENT_LENGTH, body.len().into());
            req_builder.body(hyper::Body::from(body))
        } else {
            req_builder.body(hyper::Body::default())
        };
        let request = match request_result {
            Ok(request) => request,
            Err(e) => return Box::pin(futures::future::err(Error::from(e)))
        };

        let no_return_type = self.no_return_type;
        Box::pin(conf.client
            .request(request)
            .map_err(|e| Error::from(e))
            .and_then(move |response| {
                let status = response.status();
                if !status.is_success() {
                    futures::future::err::<U, Error>(Error::from((status, response.into_body()))).boxed()
                } else if no_return_type {
                    // This is a hack; if there's no_ret_type, U is (), but serde_json gives an
                    // error when deserializing "" into (), so deserialize 'null' into it
                    // instead.
                    // An alternate option would be to require U: Default, and then return
                    // U::default() here instead since () implements that, but then we'd
                    // need to impl default for all models.
                    futures::future::ok::<U, Error>(serde_json::from_str("null").expect("serde null value")).boxed()
                } else {
                    hyper::body::to_bytes(response.into_body())
                        .map(|bytes| serde_json::from_slice(&bytes.unwrap()))
                        .map_err(|e| Error::from(e)).boxed()
                }
            }))
    }
}
