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// Copyright 2020 Parity Technologies (UK) Ltd.
// This file is part of Substrate.

// Substrate 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.

// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.

//! Policy-related types.
//!
//! Contains a `DenyUnsafe` type that can be used to deny potentially unsafe
//! RPC when accessed externally.

use jsonrpc_core as rpc;

/// Signifies whether a potentially unsafe RPC should be denied.
#[derive(Clone, Copy, Debug)]
pub enum DenyUnsafe {
    /// Denies only potentially unsafe RPCs.
    Yes,
    /// Allows calling every RPCs.
    No
}

impl DenyUnsafe {
    /// Returns `Ok(())` if the RPCs considered unsafe are safe to call,
    /// otherwise returns `Err(UnsafeRpcError)`.
    pub fn check_if_safe(self) -> Result<(), UnsafeRpcError> {
        match self {
            DenyUnsafe::Yes => Err(UnsafeRpcError),
            DenyUnsafe::No => Ok(())
        }
    }
}

/// Signifies whether an RPC considered unsafe is denied to be called externally.
#[derive(Debug)]
pub struct UnsafeRpcError;

impl std::fmt::Display for UnsafeRpcError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "RPC call is unsafe to be called externally")
    }
}

impl std::error::Error for UnsafeRpcError {}

impl From<UnsafeRpcError> for rpc::Error {
    fn from(_: UnsafeRpcError) -> rpc::Error {
        rpc::Error::method_not_found()
    }
}