// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.

// Parity Ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity Ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity Ethereum.  If not, see <http://www.gnu.org/licenses/>.

//! Transport-specific metadata extractors.

use http;
use hyper;
use jsonrpc_core;

/// HTTP RPC server impl-independent metadata extractor
pub trait HttpMetaExtractor: Send + Sync + 'static {
    /// Type of Metadata
    type Metadata: jsonrpc_core::Metadata;
    /// Extracts metadata from given params.
    fn read_metadata(&self, origin: Option<String>, user_agent: Option<String>) -> Self::Metadata;
}

pub struct MetaExtractor<T> {
    extractor: T,
}

impl<T> MetaExtractor<T> {
    pub fn new(extractor: T) -> Self {
        MetaExtractor { extractor }
    }
}

impl<M, T> http::MetaExtractor<M> for MetaExtractor<T>
where
    T: HttpMetaExtractor<Metadata = M>,
    M: jsonrpc_core::Metadata,
{
    fn read_metadata(&self, req: &hyper::Request<hyper::Body>) -> M {
        let as_string = |header: Option<&hyper::header::HeaderValue>| {
            header.and_then(|val| val.to_str().ok().map(ToOwned::to_owned))
        };

        let origin = as_string(req.headers().get("origin"));
        let user_agent = as_string(req.headers().get("user-agent"));
        self.extractor.read_metadata(origin, user_agent)
    }
}