//! Async-graphql integration with Rocket

#![warn(missing_docs)]
#![forbid(unsafe_code)]

use async_graphql::{
    IntoQueryBuilder, IntoQueryBuilderOpts, QueryBuilder, QueryResponse, Schema, Variables, ObjectType, SubscriptionType
};
use log::{error, info};
use rocket::{
    Request, Response, State,
    data::{Data, ToByteUnit},
    fairing::{AdHoc, Fairing},
    http::{ContentType, Header, Status, hyper::header::CACHE_CONTROL},
    request::{self, FromQuery, Outcome},
    response::{self, Responder, ResponseBuilder}, data::{self, FromData}
};
use std::{io::Cursor, sync::Arc};
use tokio_util::compat::Tokio02AsyncReadCompatExt;
use yansi::Paint;



pub struct GraphQL;

impl GraphQL
{
    pub fn fairing<Q, M, S>(schema: Schema<Q, M, S>) -> impl Fairing
    where
        Q: ObjectType + Send + Sync + 'static,
        M: ObjectType + Send + Sync + 'static,
        S: SubscriptionType + Send + Sync + 'static
    {
        GraphQL::attach(schema, Default::default())
    }

    pub fn fairing_with_opts<Q, M, S>(schema: Schema<Q, M, S>, opts: IntoQueryBuilderOpts) -> impl Fairing
    where
        Q: ObjectType + Send + Sync + 'static,
        M: ObjectType + Send + Sync + 'static,
        S: SubscriptionType + Send + Sync + 'static
    {
        GraphQL::attach(schema, opts)
    }

    fn attach<Q, M, S>(schema: Schema<Q, M, S>, opts: IntoQueryBuilderOpts) -> impl Fairing
    where
        Q: ObjectType + Send + Sync + 'static,
        M: ObjectType + Send + Sync + 'static,
        S: SubscriptionType + Send + Sync + 'static
    {
        AdHoc::on_attach("GraphQL", move |rocket| async move {
            let emoji = if cfg!(windows) {""} else {"📄 "};
            info!("{}{}", Paint::masked(emoji), Paint::magenta(format!("GraphQL {}:", Paint::blue(""))).wrap());

            Ok(rocket.manage(schema)
                    .manage(Arc::new(opts))
            )
        })
    }
}

pub struct GQLRequest(pub QueryBuilder);

impl GQLRequest {
    pub async fn execute<Q, M, S>(self, schema: &Schema<Q, M, S>) -> Result<GQLResponse, Status>
    where
        Q: ObjectType + Send + Sync + 'static,
        M: ObjectType + Send + Sync + 'static,
        S: SubscriptionType + Send + Sync + 'static
    {
        self.0.execute(schema)
            .await
            .map(GQLResponse)
            .map_err(|e| {
                error!("{}", e);
                Status::BadRequest
            })
    }
}

impl<'q> FromQuery<'q> for GQLRequest {
    type Error = String;

    fn from_query(query_items: request::Query) -> Result<Self, Self::Error> {
        let mut query = None;
        let mut operation_name = None;
        let mut variables = None;

        for query_item in query_items {
            let (key, value) = query_item.key_value();
            match key.as_str() {
                "query" => {
                    if query.is_some() {
                        return Err(r#"Multiple parameters named \"query\" found. Only one parameter by that name is allowed."#.to_string());
                    } else {
                        query = value.url_decode()
                            .map_err(|e| e.to_string())?
                            .into();
                    }
                }
                "operation_name" => {
                    if operation_name.is_some() {
                        return Err(r#"Multiple parameters named \"operation_name\" found. Only one parameter by that name is allowed."#.to_string());
                    } else {
                        operation_name = value.url_decode()
                            .map_err(|e| e.to_string())?
                            .into();
                    }
                }
                "variables" => {
                    if variables.is_some() {
                        return Err(r#"Multiple parameters named \"variables\" found. Only one parameter by that name is allowed."#.to_string());
                    } else {
                        let decoded= value.url_decode()
                            .map_err(|e| e.to_string())?;
                        let json_value = serde_json::from_str::<serde_json::Value>(&decoded)
                            .map_err(|e| e.to_string())?;
                        variables = Variables::parse_from_json(json_value)
                            .map_err(|e| e.to_string())?
                            .into();
                    }
                }
                _ => {
                    return Err(format!(r#"Extra parameter named \"{}\" found. Extra parameters are not allowed."#, key));
                }
            }
        }

        if let Some(query_source) = query {
            let mut builder = QueryBuilder::new(query_source);

            if let Some(variables) = variables {
                builder = builder.variables(variables);
            }

            if let Some(operation_name) = operation_name {
                builder = builder.operation_name(operation_name);
            }

            Ok(GQLRequest(builder))
        } else {
            Err(r#"Parameter "query" missing from request."#.to_string())
        }
    }
}

#[rocket::async_trait]
impl FromData for GQLRequest {
    type Error = String;

    async fn from_data(req: &Request<'_>, data: Data) -> data::Outcome<Self, Self::Error> {
        let opts = match req.guard::<State<'_, Arc<IntoQueryBuilderOpts>>>().await {
            Outcome::Success(opts) => opts,
            Outcome::Failure(_) => return data::Outcome::Failure((Status::InternalServerError, "Missing IntoQueryBuilderOpts in State".to_string())),
            Outcome::Forward(()) => unreachable!(),
        };

        let stream = data.open(100.kibibytes());
        let builder = (req.headers().get_one("Content-Type"), stream.compat())
            .into_query_builder_opts(&opts)
            .await;

        match builder {
            Ok(builder) => data::Outcome::Success(GQLRequest(builder)),
            Err(e) => data::Outcome::Failure((Status::BadRequest, format!("{}", e))),
        }
    }
}

pub struct GQLResponse(pub QueryResponse);

impl<'r> Responder<'r, 'static> for GQLResponse {
    fn respond_to(self, _: &'r Request<'_>) -> response::Result<'static> {
        let gql_resp = async_graphql::http::GQLResponse(Ok(self.0));
        let body = serde_json::to_string(&gql_resp).unwrap();

        Response::build()
            .header(ContentType::new("application", "json"))
            .status(Status::Ok)
            .sized_body(body.len(), Cursor::new(body))
            .cache_control(&gql_resp.0)
            .ok()
    }
}

/// Extension trait, to allow the use of `cache_control` with for example `ResponseBuilder`.
pub trait CacheControl{
    /// Add the `async-graphql::query::QueryResponse` cache control value as header to the Rocket response.
    fn cache_control(&mut self, resp: &async_graphql::Result<QueryResponse>) -> &mut Self;
}

impl<'r> CacheControl for ResponseBuilder<'r> {
    fn cache_control(&mut self, resp: &async_graphql::Result<QueryResponse>) -> &mut ResponseBuilder<'r> {
        match resp {
            Ok(resp) if resp.cache_control.value().is_some() => {
                self.header(Header::new(CACHE_CONTROL.as_str(), resp.cache_control.value().unwrap()))
            }
            _ => self,
        }
    }
}