// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

use std::io::Write;
use std::path::PathBuf;

use bytes::Buf;
use tokio::io::AsyncWriteExt;

use crate::raw::*;
use crate::*;

pub struct FsWriter<F> {
    target_path: PathBuf,
    tmp_path: Option<PathBuf>,

    f: Option<F>,
}

impl<F> FsWriter<F> {
    pub fn new(target_path: PathBuf, tmp_path: Option<PathBuf>, f: F) -> Self {
        Self {
            target_path,
            tmp_path,

            f: Some(f),
        }
    }
}

/// # Safety
///
/// We will only take `&mut Self` reference for FsWriter.
unsafe impl<F> Sync for FsWriter<F> {}

impl oio::Write for FsWriter<tokio::fs::File> {
    async fn write(&mut self, bs: Buffer) -> Result<usize> {
        let f = self.f.as_mut().expect("FsWriter must be initialized");

        // TODO: use write_vectored instead.
        f.write(bs.chunk()).await.map_err(new_std_io_error)
    }

    async fn close(&mut self) -> Result<()> {
        let f = self.f.as_mut().expect("FsWriter must be initialized");
        f.flush().await.map_err(new_std_io_error)?;
        f.sync_all().await.map_err(new_std_io_error)?;

        if let Some(tmp_path) = &self.tmp_path {
            tokio::fs::rename(tmp_path, &self.target_path)
                .await
                .map_err(new_std_io_error)?;
        }
        Ok(())
    }

    async fn abort(&mut self) -> Result<()> {
        if let Some(tmp_path) = &self.tmp_path {
            tokio::fs::remove_file(tmp_path)
                .await
                .map_err(new_std_io_error)
        } else {
            Err(Error::new(
                ErrorKind::Unsupported,
                "Fs doesn't support abort if atomic_write_dir is not set",
            ))
        }
    }
}

impl oio::BlockingWrite for FsWriter<std::fs::File> {
    fn write(&mut self, bs: Buffer) -> Result<usize> {
        let f = self.f.as_mut().expect("FsWriter must be initialized");

        f.write(bs.chunk()).map_err(new_std_io_error)
    }

    fn close(&mut self) -> Result<()> {
        if let Some(f) = self.f.take() {
            f.sync_all().map_err(new_std_io_error)?;

            if let Some(tmp_path) = &self.tmp_path {
                std::fs::rename(tmp_path, &self.target_path).map_err(new_std_io_error)?;
            }
        }

        Ok(())
    }
}
