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// Copyright 2020 Sigma Prime Pty Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

use crate::rpc_proto;
use base64::encode;
use prost::Message;
use sha2::{Digest, Sha256};
use std::fmt;

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct TopicHash {
    /// The topic hash. Stored as a string to align with the protobuf API.
    hash: String,
}

impl TopicHash {
    pub fn from_raw(hash: impl Into<String>) -> TopicHash {
        TopicHash { hash: hash.into() }
    }

    pub fn into_string(self) -> String {
        self.hash
    }

    pub fn as_str(&self) -> &str {
        &self.hash
    }
}

/// A gossipsub topic.
#[derive(Debug, Clone)]
pub struct Topic {
    topic: String,
}

impl Topic {
    pub fn new(topic: String) -> Self {
        Topic { topic }
    }

    /// Creates a `TopicHash` by SHA256 hashing the topic then base64 encoding the
    /// hash.
    pub fn sha256_hash(&self) -> TopicHash {
        let topic_descripter = rpc_proto::TopicDescriptor {
            name: Some(self.topic.clone()),
            auth: None,
            enc: None,
        };
        let mut bytes = Vec::with_capacity(topic_descripter.encoded_len());
        topic_descripter
            .encode(&mut bytes)
            .expect("buffer is large enough");
        let hash = encode(Sha256::digest(&bytes).as_slice());

        TopicHash { hash }
    }

    /// Creates a `TopicHash` as a raw string.
    pub fn no_hash(&self) -> TopicHash {
        TopicHash {
            hash: self.topic.clone(),
        }
    }
}

impl fmt::Display for Topic {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.topic)
    }
}

impl fmt::Display for TopicHash {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.hash)
    }
}