morethantext-web/src/morethantext/cache.rs

use super::{DBError, FileData, SessionData, Store};
use async_std::{fs::write, path::Path};
use rand::{distributions::Alphanumeric, thread_rng, Rng};
use std::{
    cell::Cell,
    slice,
    str,
    time::{Duration, Instant},
};

#[derive(Clone)]
enum DataType {
    DBMap(Store),
}

impl DataType {
    fn new(data_type: &str) -> Result<Self, DBError> {
        match data_type {
            "store" => Ok(DataType::DBMap(Store::new())),
            _ => Err(DBError::new("invalid data type")),
        }
    }
}

impl SessionData for DataType {
    fn add(&mut self, key: &str, value: &str, data: &str) -> Result<Vec<String>, DBError> {
        match self {
            DataType::DBMap(dbs) => dbs.add(key, value, data),
        }
    }

    fn eq(&self, key: &str, value: &str) -> Result<Vec<String>, DBError> {
        match self {
            DataType::DBMap(dbs) => dbs.eq(key, value),
        }
    }

    fn list(&self, keys: Vec<&str>) -> Result<Vec<String>, DBError> {
        match self {
            DataType::DBMap(dbs) => dbs.list(keys),
        }
    }
}

impl FileData<Self> for DataType {
    fn to_bytes(&self) -> Vec<u8> {
        let mut output = Vec::new();
        match self {
            DataType::DBMap(store) => {
                output.append(&mut "DBMap".as_bytes().to_vec());
                output.push(0);
                output.append(&mut store.to_bytes());
            },
        }
        output
    }

    fn from_bytes(data: &mut slice::Iter<u8>) -> Result<Self, DBError> {
        let mut header: Vec<u8> = Vec::new();
        loop {
            let letter = match data.next() {
                Some(a) => a.clone(),
                None => 0,
            };
            if letter == 0 {
                break;
            } else {
                header.push(letter);
            }
        }
        let header = match str::from_utf8(&header) {
            Ok(item) => item,
            Err(_) => return Err(DBError::new("file corruption")),
        };
        match header {
            "DBMap" => {
                match Store::from_bytes(data) {
                    Ok(store) => Ok(DataType::DBMap(store)),
                    Err(err) => Err(err),
                }
            },
            _ => Err(DBError::new("file corruption")),
        }
    }
}

struct Entry {
    data: DataType,
    filename: String,
    last_used: Cell<Instant>,
}

impl Entry {
    async fn new(filename: String, data: DataType) -> Result<Self, DBError> {
        if Path::new(&filename).exists().await {
            return Err(DBError::new("entry already exists"));
        }
        Ok(Self {
            data: data,
            filename: filename,
            last_used: Cell::new(Instant::now()),
        })
    }

    async fn get(&self) -> Result<DataType, DBError> {
        Ok(self.data.clone())
    }
}

struct Cache;

impl Cache {
    async fn new(dir: &str) -> Self {
        Self
    }
}

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

    #[test]
    fn invalid_cache_type() -> Result<(), DBError> {
        match DataType::new("dkhgdl") {
            Ok(_) => Err(DBError::new("invalid data type should raise an error")),
            Err(err) => {
                assert_eq!(err.to_string(), "invalid data type");
                Ok(())
            }
        }
    }

    #[test]
    fn create_storage() {
        let dbs = DataType::new("store").unwrap();
        let expected: Vec<String> = Vec::new();
        assert_eq!(dbs.list(["database"].to_vec()).unwrap(), expected);
    }

    #[test]
    fn update_storage() {
        let mut dbs = DataType::new("store").unwrap();
        let name = "new_database";
        let id = "someid";
        dbs.add("database", name, id).unwrap();
        assert_eq!(dbs.eq("database", name).unwrap(), [id].to_vec());
        assert_eq!(dbs.list(["database"].to_vec()).unwrap(), [name].to_vec());
    }
}

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

    #[test]
    fn new_store_bytes() {
        let dbs = DataType::new("store").unwrap();
        let mut expected = "DBMap".as_bytes().to_vec();
        expected.push(0);
        assert_eq!(dbs.to_bytes(), expected);
    }

    #[test]
    fn store_bytes_with_info() {
        let name = "title";
        let id = "king";
        let mut store = Store::new();
        let mut dt_store = DataType::new("store").unwrap();
        let mut expected = dt_store.to_bytes();
        store.add("database", name, id);
        expected.append(&mut store.to_bytes());
        dt_store.add("database", name, id);
        assert_eq!(dt_store.to_bytes(), expected);
    }

    #[test]
    fn read_empty_store() {
        let dt_store = DataType::new("store").unwrap();
        let data = dt_store.to_bytes();
        let mut feed = data.iter();
        let output = DataType::from_bytes(&mut feed).unwrap();
        assert_eq!(dt_store.list(["database"].to_vec()).unwrap(), output.list(["database"].to_vec()).unwrap());
    }

    #[test]
    fn read_store_info() {
        let mut dt_store = DataType::new("store").unwrap();
        dt_store.add("database", "raven", "beastboy").unwrap();
        let data = dt_store.to_bytes();
        let mut feed = data.iter();
        let output = DataType::from_bytes(&mut feed).unwrap();
        assert_eq!(dt_store.list(["database"].to_vec()).unwrap(), output.list(["database"].to_vec()).unwrap());
    }

    #[test]
    fn read_bad_header() -> Result<(), DBError> {
        let data = "sdghsdl".as_bytes().to_vec();
        let mut feed = data.iter();
        match DataType::from_bytes(&mut feed) {
            Ok(_) => Err(DBError::new("should have raised an error")),
            Err(err) => {
                assert_eq!(err.to_string(), "file corruption");
                Ok(())
            },
        }
    }

    #[test]
    fn read_bad_store() -> Result<(), DBError> {
        let mut data = "DBMap".as_bytes().to_vec();
        data.push(0);
        data.append(&mut "sdfgs".as_bytes().to_vec());
        let mut feed = data.iter();
        match DataType::from_bytes(&mut feed) {
            Ok(_) => Err(DBError::new("should have raised an error")),
            Err(err) => {
                assert_eq!(err.to_string(), "file corruption");
                Ok(())
            },
        }
    }
}

#[cfg(test)]
mod entry {
    use super::*;
    use tempfile::tempdir;

    #[async_std::test]
    async fn create() {
        let dir = tempdir().unwrap();
        let mut data = DataType::new("store").unwrap();
        data.add("database", "roger", "moore").unwrap();
        let filepath = dir.path().join("wiliam");
        let filename = filepath.to_str().unwrap();
        let item = Entry::new(filename.to_string(), data.clone())
            .await
            .unwrap();
        let output = item.get().await.unwrap();
        assert_eq!(
            data.list(["database"].to_vec()).unwrap(),
            output.list(["database"].to_vec()).unwrap()
        );
    }

    #[async_std::test]
    async fn no_over_writes() -> Result<(), DBError> {
        let dir = tempdir().unwrap();
        let id = "wicked";
        let file = dir.path().join(id);
        let filename = file.to_str().unwrap();
        write(&file, b"previous").await.unwrap();
        let data = DataType::new("store").unwrap();
        match Entry::new(filename.to_string(), data).await {
            Ok(_) => {
                return Err(DBError::new(
                    "Should produce an error for an existing Entry",
                ))
            }
            Err(err) => {
                assert_eq!(err.to_string(), "entry already exists");
                Ok(())
            }
        }
    }
}

#[cfg(test)]
mod cache {
    use super::*;
    use tempfile::tempdir;

    #[async_std::test]
    async fn create() {
        let dir = tempdir().unwrap();
        Cache::new(dir.path().to_str().unwrap()).await;
    }
}