#![feature(io_error_more)]

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

use config::SharedAppConfig;
use model::{FileName, LocalPath, UniqueName};

#[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))
            }
        }
    };
}

#[macro_export]
macro_rules! query_fs {
    ($fs: expr, $msg: expr, default $fail: expr) => {
        match $fs.send($msg).await {
            Ok(Ok(r)) => r,
            Ok(Err(e)) => {
                log::error!("{e}");
                $fail
            }
            Err(e) => {
                log::error!("{e:?}");
                $fail
            }
        }
    };
    ($fs: expr, $msg: expr, panic) => {
        match $fs.send($msg).await {
            Ok(Ok(r)) => r,
            Ok(Err(e)) => {
                log::error!("{e}");
                panic!("{:?}", e);
            }
            Err(e) => {
                log::error!("{e:?}");
                panic!("{:?}", e);
            }
        }
    };

    ($fs: expr, $msg: expr, $fail: expr) => {
        $crate::query_fs!($fs, $msg, $fail, $fail)
    };

    ($fs: expr, $msg: expr, $db_fail: expr, $act_fail: expr) => {
        match $fs.send($msg).await {
            Ok(Ok(r)) => r,
            Ok(Err(e)) => {
                log::error!("{e}");
                return Err($db_fail);
            }
            Err(e) => {
                log::error!("{e:?}");
                return Err($act_fail);
            }
        }
    };
}

#[derive(Debug, Copy, Clone, serde::Serialize, thiserror::Error)]
#[serde(rename_all = "kebab-case", tag = "fs")]
pub enum Error {
    #[error("Can't access file system. Please check privileges")]
    StorageUnavailable,
    #[error("Can't write to file. Please check privileges.")]
    CantWrite,
    #[error("Can't write to file. There's no more space on disk")]
    NoSpace,
    #[error("Can't remove file. Please check privileges.")]
    CantRemove,
    #[error("Can't write to file. Invalid path, no filename")]
    InvalidPath,
}

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

#[derive(Clone)]
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();

        tokio::fs::create_dir_all(&output_path).await.ok();

        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) => {
            log::error!("{:?}", e);
            Err(Error::CantRemove)
        }
    }
}

pub struct WriteResult {
    /// Unique file name created with UUID and original file extension
    pub unique_name: UniqueName,
    /// Path to file in local storage
    pub local_path: LocalPath,
    pub file_name: FileName,
}

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

fs_async_handler!(WriteFile, write_file, WriteResult);

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

    log::debug!("Writing file {:?}", file_name);

    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 unique_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(&unique_name);
    log::debug!(
        "File {:?} will be written as {:?} at {:?}",
        file_name,
        unique_name,
        path
    );
    let mut file = match std::fs::File::create(&path) {
        Ok(f) => f,
        Err(e) => {
            log::error!("{:?}", e);
            return Err(Error::CantWrite);
        }
    };

    let mut counter = 0;
    while let Some(b) = stream.recv().await {
        counter += 1;
        if counter % 100_000 == 0 {
            log::debug!("Wrote {} for {:?}", counter, file_name);
        }
        match file.write(&b) {
            Ok(_) => {}
            Err(e) if e.kind() == std::io::ErrorKind::StorageFull => return Err(Error::NoSpace),
            Err(e) => {
                log::error!("{:?}", e);
                return Err(Error::CantWrite);
            }
        }
    }
    log::debug!("File {:?} successfully written", unique_name);

    Ok(WriteResult {
        file_name: FileName::new(file_name),
        unique_name: UniqueName::new(unique_name),
        local_path: LocalPath::new(path.to_str().unwrap_or_default()),
    })
}