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use core::convert::TryFrom;

use crate::error::{Error, Result};

/// The version of the CID.
#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Debug, Hash)]
#[cfg_attr(feature = "scale-codec", derive(parity_scale_codec::Decode))]
#[cfg_attr(feature = "scale-codec", derive(parity_scale_codec::Encode))]
#[cfg_attr(feature = "serde-codec", derive(serde::Deserialize))]
#[cfg_attr(feature = "serde-codec", derive(serde::Serialize))]
pub enum Version {
  /// CID version 0.
  V0,
  /// CID version 1.
  V1,
}

impl Version {
  /// Check if the version of `data` string is CIDv0.
  pub fn is_v0_str(data: &str) -> bool {
    // v0 is a Base58Btc encoded sha hash, so it has
    // fixed length and always begins with "Qm"
    data.len() == 46 && data.starts_with("Qm")
  }

  /// Check if the version of `data` bytes is CIDv0.
  pub fn is_v0_binary(data: &[u8]) -> bool {
    data.len() == 34 && data.starts_with(&[0x12, 0x20])
  }
}

/// Convert a number to the matching version, or `Error` if no valid version is
/// matching.
impl TryFrom<u64> for Version {
  type Error = Error;

  fn try_from(raw: u64) -> Result<Self> {
    match raw {
      0 => Ok(Self::V0),
      1 => Ok(Self::V1),
      _ => Err(Error::InvalidCidVersion),
    }
  }
}

impl From<Version> for u64 {
  fn from(ver: Version) -> u64 {
    match ver {
      Version::V0 => 0,
      Version::V1 => 1,
    }
  }
}