use crate::success;
use clap;
use parse_display_derive::Display;
use hmac::{Hmac, Mac};
use serde::{
  Serialize,
  Deserialize,
  de::DeserializeOwned,
};
use sha2::Sha512;
use ureq::post;
type HmacSHA512 = Hmac<Sha512>;

#[derive(Serialize, Deserialize, Debug, Eq, Hash, PartialEq, clap::Args, Clone, Display)]
#[display("{api_id}")]
/// Used to specify API credentials. These are not required as long as LUNANODE_KEY_ID and LUNANODE_API_KEY are specified in the environment.
pub struct ApiKeys {
  #[clap(long, env="LUNANODE_KEY_ID", help="The API key ID from the Lunanode Dashboard.", long_help="The API key ID from the Lunanode dashboard. You may also specify this option via the LUNANODE_KEY_ID environment variable.", required=false)]
  /// The API id string as used by LunaNode. This should be exactly 16 bytes. This will get enforced at a later date.
  pub api_id: String,
  #[serde(skip)]
  #[clap(long, env="LUNANODE_API_KEY", help="The Lunanode API key received from the dashboard.", long_help="The Lunanode API key recieved from the dashboard. This option may also be set by the LUNANODE_API_KEY environemnt variable.", required=false)]
  /// Used for convenience. It is not serialized nor deserializes; this means that this object can NOT be deserialized at all, since this is not an Option<String>. 
  /// This is used to fill in the api_paritlakey field, and to give the request a way to access the api key locally.
  pub api_key: String,
  #[clap(long, env="LUNANODE_API_PARTIALKEY", help="The Lunanode API key received from the dashboard, but only the first 64 bytes of it.", long_help="The Lunanode API key recieved from the dashboard. This option may also be set by the LUNANODE_API_PARTIALKEY environemnt variable. This should be autogenerated based on the LUNANODE_API_KEY, but it isn't. TODO.", required=false)]
  /// The api_paritalkey field as used by LunaNode (the first 64 bytes of the api_key). Note that this field is autofilled.
  /// Since this should always be a 64 byte array, this will be enforced at some point in the future. TODO
  pub api_partialkey: String,
}

pub trait LunaNodeResponse: DeserializeOwned {}
pub trait LunaNodeRequest: Serialize + std::fmt::Debug {
  /// The resposne type you expect after making this request.
  /// Setting this will allow acces to a generic function, make_request, that will expect this type to be recieved.
  /// See: make_request
  type Response: LunaNodeResponse;

  /// Can't genericize this one out. You need to implenent a function which can return a set of API keys for creating an API requst.
  fn get_keys(&self) -> ApiKeys;
  /// The LunaNode API endpoint you'll be using.
  /// Note: do *NOT* add a leading slash, but *DO* include a trailing slash.
  /// The three wrong ways: "/vm/list", "vm/list", "/vm/list",
  /// The only correct way: "vm/list/".
  fn url_endpoint(&self) -> String;
  /// A generic function to recieve a specific relsponse type from the server.
  /// The Self::response type is the type you're expecting. In the case that this type is incorrect, or the server returns bad data, you will receive an LNError::SerdeError(serde::Error, String), with the String being a raw response from the server.
  /// You may also recieve any other error defined in LNError, including timezone errors due to not being able to create a nonce value for the request.
  /// See LNError.
  fn make_request(&self) -> Result<Self::Response, LNError> {
    make_request::<Self, Self::Response>(self)
  }
}

#[derive(Serialize, Deserialize, Debug)]
pub struct LNErrorResponse {
  #[serde(with="success")]
  success: bool,
  error: String, // proper type, full accoutnign of the error from the API
}
impl std::fmt::Display for LNErrorResponse {
  fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
    write!(f, "An API error has occured! {}", self.error)
  }
}
impl std::error::Error for LNErrorResponse {}

#[derive(Debug)]
pub enum LNError {
  RequestError(ureq::Error),
  DeserializationError(std::io::Error),
  TimeError(std::time::SystemTimeError),
  LunaNodeError(LNErrorResponse),
  SerdeError(serde_json::Error, String), // the serde error, accompanied by a raw string
  GetFuckedError,
}
impl std::fmt::Display for LNError {
  fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
    write!(f, "An error has occured! {}", self)
  }
}
impl std::error::Error for LNError {}

fn make_request<S, D>(req: &S) -> Result<D, LNError>
  where S: LunaNodeRequest + ?Sized,
        D: LunaNodeResponse
{
  let json_req_data = match serde_json::to_string(req) {
    Ok(jrd) => jrd,
    Err(e) => return Err(LNError::SerdeError(e, format!("{:?}", req))),
  };
  let epoch = match std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH) {
    Err(e) => return Err(LNError::TimeError(e)),
    Ok(ue) => ue,
  }.as_secs();
  let nonce = format!("{}", epoch);
  let mut hmac = HmacSHA512::new_from_slice(req.get_keys().api_key.as_bytes()).expect("SHA512 accepts text of any size.");
  let hmac_input = format!("{}|{}|{}", req.url_endpoint(), &json_req_data, nonce);
  hmac.update(hmac_input.as_bytes());
  let signature = hex::encode(hmac.finalize().into_bytes());
  let full_url = format!("https://dynamic.lunanode.com/api/{}", req.url_endpoint());
  match post(&full_url)
    .send_form(&[
      ("req", &json_req_data),
      ("signature", &signature),
      ("nonce", &nonce),
    ]) {
    Err(e) => Err(LNError::RequestError(e)),
    Ok(resp) => {
      let resp_str = match resp.into_string() {
        Err(e) => return Err(LNError::DeserializationError(e)),
        Ok(s) => s,
      };
      println!("RESP: {}", resp_str);
      match serde_json::from_str::<LNErrorResponse>(&resp_str) {
        Ok(e) => return Err(LNError::LunaNodeError(e)),
        Err(_e) => false,
      };
      match serde_json::from_str::<D>(&resp_str) {
        Ok(s) => Ok(s),
        Err(e) => Err(LNError::SerdeError(e, resp_str)),
      }
    },
  }
}