use super::PathInfoService;
use crate::{proto, Error};
use prost::Message;
use std::path::PathBuf;
use tracing::warn;

/// SledPathInfoService stores PathInfo in a [sled](https://github.com/spacejam/sled).
///
/// The PathInfo messages are stored as encoded protos, and keyed by their output hash,
/// as that's currently the only request type available.
#[derive(Clone)]
pub struct SledPathInfoService {
    db: sled::Db,
}

impl SledPathInfoService {
    pub fn new(p: PathBuf) -> Result<Self, sled::Error> {
        let config = sled::Config::default().use_compression(true).path(p);
        let db = config.open()?;

        Ok(Self { db })
    }

    pub fn new_temporary() -> Result<Self, sled::Error> {
        let config = sled::Config::default().temporary(true);
        let db = config.open()?;

        Ok(Self { db })
    }
}

impl PathInfoService for SledPathInfoService {
    fn get(&self, digest: [u8; 20]) -> Result<Option<proto::PathInfo>, Error> {
        match self.db.get(digest) {
            Ok(None) => Ok(None),
            Ok(Some(data)) => match proto::PathInfo::decode(&*data) {
                Ok(path_info) => Ok(Some(path_info)),
                Err(e) => {
                    warn!("failed to decode stored PathInfo: {}", e);
                    Err(Error::StorageError(format!(
                        "failed to decode stored PathInfo: {}",
                        e
                    )))
                }
            },
            Err(e) => {
                warn!("failed to retrieve PathInfo: {}", e);
                Err(Error::StorageError(format!(
                    "failed to retrieve PathInfo: {}",
                    e
                )))
            }
        }
    }

    fn put(&self, path_info: proto::PathInfo) -> Result<proto::PathInfo, Error> {
        // Call validate on the received PathInfo message.
        match path_info.validate() {
            Err(e) => Err(Error::InvalidRequest(format!(
                "failed to validate PathInfo: {}",
                e
            ))),
            // In case the PathInfo is valid, and we were able to extract a NixPath, store it in the database.
            // This overwrites existing PathInfo objects.
            Ok(nix_path) => match self.db.insert(nix_path.digest, path_info.encode_to_vec()) {
                Ok(_) => Ok(path_info),
                Err(e) => {
                    warn!("failed to insert PathInfo: {}", e);
                    Err(Error::StorageError(format! {
                        "failed to insert PathInfo: {}", e
                    }))
                }
            },
        }
    }
}