// SPDX-License-Identifier: GPL-3.0-or-later
use crate::FbError;
use bincode::{Options, DefaultOptions};

#[cfg(feature = "base64")]
use base64::prelude::{BASE64_STANDARD, Engine};

#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};

/// An object that represents a message specific key.
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct FbKey(pub(crate) Vec<Vec<(usize, usize)>>);


impl FbKey {

	/// Returns the byte representation of the message specific key.
	pub fn to_bytes(&self) -> Vec<u8> {
		let binc = DefaultOptions::new();

		binc.serialize(&self.0)
			.expect("Should be fine")
	}

	/// Constructs the message specific key from the provided bytes.
	/// # Errors
	/// [DecodeError](FbError::DecodeError)
	pub fn from_bytes(fbkey: &[u8]) -> Result<FbKey, FbError> {
		let binc = DefaultOptions::new();
		let indices: Vec<_> = binc.deserialize(&fbkey)
			.map_err(|_| FbError::DecodeError)?;
		if indices.len() < 2 {
			return Err(FbError::DecodeError);
		}

		Ok (FbKey(indices))
	}

	/// Returns the base64 encoded representation of the message specific key.
	#[cfg(feature = "base64")]
	pub fn to_base64(&self) -> String {
		BASE64_STANDARD.encode(&self.to_bytes())
	}

	/// Constructs the message specific key from the provided base64 encoded form.
	/// # Errors
	/// [DecodeError](FbError::DecodeError)
	#[cfg(feature = "base64")]
	pub fn from_base64(key_str: &str) -> Result<FbKey, FbError> {
		let indice_bytes = BASE64_STANDARD.decode(key_str)
			.map_err(|_| FbError::DecodeError)?;

		Self::from_bytes(&indice_bytes)
	}
}