#![feature(io_error_more)]

use std::ffi::OsStr;
use std::io::Write;

use config::SharedAppConfig;
use model::FileName;

#[macro_export]
macro_rules! fs_async_handler {
    ($msg: ty, $async: ident, $res: ty) => {
        impl actix::Handler<$msg> for FsManager {
            type Result = actix::ResponseActFuture<Self, Result<$res>>;

            fn handle(&mut self, msg: $msg, _ctx: &mut Self::Context) -> Self::Result {
                use actix::WrapFuture;
                let config = self.config.clone();
                Box::pin(async { $async(msg, config).await }.into_actor(self))
            }
        }
    };
}

#[derive(Debug, thiserror::Error)]
pub enum Error {
    #[error("Can't access file system. Please check privileges")]
    StorageUnavailable,
    #[error("Can't write to file. Please check privileges. {0:?}")]
    CantWrite(std::io::Error),
    #[error("Can't write to file. There's no more space on disk")]
    NoSpace,
    #[error("Can't remove file. Please check privileges. {0:?}")]
    CantRemove(std::io::Error),
    #[error("Can't write to file. Invalid path, no filename")]
    InvalidPath,
}

pub type Result<T> = std::result::Result<T, Error>;

pub struct FsManager {
    config: SharedAppConfig,
}

impl actix::Actor for FsManager {
    type Context = actix::Context<FsManager>;
}

impl FsManager {
    pub async fn build(config: SharedAppConfig) -> Result<Self> {
        Self::validate_fs(config.clone()).await?;
        Ok(Self { config })
    }

    async fn validate_fs(config: SharedAppConfig) -> Result<()> {
        let l = config.lock();
        let output_path = l.files().local_path();
        let test_file = std::path::PathBuf::new()
            .join(output_path)
            .join(format!("{}", uuid::Uuid::new_v4()));
        tokio::fs::remove_file(test_file.clone()).await.ok();
        tokio::fs::write(test_file.clone(), b"1")
            .await
            .map_err(|_| Error::StorageUnavailable)?;
        tokio::fs::remove_file(test_file.clone())
            .await
            .map_err(|_| Error::StorageUnavailable)
    }
}

#[derive(actix::Message)]
#[rtype(result = "Result<()>")]
pub struct RemoveFile {
    pub file_name: String,
}

fs_async_handler!(RemoveFile, remove_file, ());

pub(crate) async fn remove_file(msg: RemoveFile, config: SharedAppConfig) -> Result<()> {
    let output_path = {
        let l = config.lock();
        l.files().local_path()
    };
    match tokio::fs::remove_file(
        std::path::PathBuf::new()
            .join(output_path)
            .join(msg.file_name),
    )
    .await
    {
        Ok(_) => Ok(()),
        Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(()),
        Err(e) => Err(Error::CantRemove(e)),
    }
}

#[derive(actix::Message)]
#[rtype(result = "Result<FileName>")]
pub struct WriteFile {
    pub file_name: String,
    pub stream: tokio::sync::mpsc::UnboundedReceiver<u8>,
}

fs_async_handler!(WriteFile, write_file, FileName);

pub(crate) async fn write_file(msg: WriteFile, config: SharedAppConfig) -> Result<FileName> {
    let WriteFile {
        file_name,
        mut stream,
    } = msg;

    let p = std::path::Path::new(&file_name);
    let ext = p
        .file_name()
        .and_then(OsStr::to_str)
        .map(std::path::Path::new)
        .and_then(std::path::Path::extension)
        .and_then(OsStr::to_str)
        .map(String::from);

    let file_name = format!(
        "{}{}",
        uuid::Uuid::new_v4(),
        ext.map(|s| format!(".{s}")).unwrap_or_default()
    );

    let output_path = {
        let l = config.lock();
        l.files().local_path()
    };

    let path = std::path::PathBuf::new().join(output_path).join(&file_name);
    let mut file = match std::fs::File::create(path) {
        Ok(f) => f,
        Err(e) => return Err(Error::CantWrite(e)),
    };

    while let Some(b) = stream.recv().await {
        match file.write(&[b]) {
            Ok(_) => {}
            Err(e) if e.kind() == std::io::ErrorKind::StorageFull => return Err(Error::NoSpace),
            Err(e) => return Err(Error::CantWrite(e)),
        }
    }
    Ok(FileName::from(file_name))
}