zarrs_metadata_ext 0.4.4

use derive_more::{Display, From};
use serde::{Deserialize, Serialize};
use zarrs_metadata::v3::MetadataV3;
use zarrs_metadata::{ChunkShape, ConfigurationSerialize};

/// A wrapper to handle various versions of Sharding codec configuration parameters.
#[derive(Serialize, Deserialize, Clone, Eq, PartialEq, Debug, Display, From)]
#[non_exhaustive]
#[serde(untagged)]
pub enum ShardingCodecConfiguration {
    /// Version 1.0.
    V1(ShardingCodecConfigurationV1),
}

impl ConfigurationSerialize for ShardingCodecConfiguration {}

/// Sharding codec configuration parameters.
///
/// See <https://zarr-specs.readthedocs.io/en/latest/v3/codecs/sharding-indexed/index.html#configuration-parameters>.
#[derive(Serialize, Deserialize, Clone, Eq, PartialEq, Debug, Display)]
#[serde(deny_unknown_fields)]
#[display("{}", serde_json::to_string(self).unwrap_or_default())]
pub struct ShardingCodecConfigurationV1 {
    /// An array of integers specifying the shape of the inner chunks in a shard along each dimension of the outer array.
    pub chunk_shape: ChunkShape,
    /// A list of codecs to be used for encoding and decoding inner chunks.
    pub codecs: Vec<MetadataV3>,
    /// A list of codecs to be used for encoding and decoding the shard index.
    pub index_codecs: Vec<MetadataV3>,
    /// Specifies whether the shard index is located at the beginning or end of the file.
    #[serde(default)]
    pub index_location: ShardingIndexLocation,
}

/// The sharding index location.
#[derive(Serialize, Deserialize, Clone, Copy, Eq, PartialEq, Debug, Display, Default)]
#[serde(rename_all = "lowercase")]
pub enum ShardingIndexLocation {
    /// The index is at the start of the shard, before the chunks.
    Start,
    /// The index is at the end of the shard, after the chunks.
    #[default]
    End,
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn codec_sharding_configuration() {
        const JSON: &str = r#"{
            "chunk_shape": [2, 2],
            "codecs": [
                {
                    "name": "bytes",
                    "configuration": {
                        "endian": "little"
                    }
                }
            ],
            "index_codecs": [
                {
                    "name": "bytes",
                    "configuration": {
                        "endian": "little"
                    }
                }
            ]
        }"#;
        let config = serde_json::from_str::<ShardingCodecConfiguration>(JSON).unwrap();

        // check that index_location is added if missing
        assert_eq!(
            config.to_string(),
            r#"{"chunk_shape":[2,2],"codecs":[{"name":"bytes","configuration":{"endian":"little"}}],"index_codecs":[{"name":"bytes","configuration":{"endian":"little"}}],"index_location":"end"}"#
        );

        let ShardingCodecConfiguration::V1(config) = config;
        assert_eq!(config.index_location, ShardingIndexLocation::End);
    }
}