ferrijs-std 0.2.1

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
#![allow(clippy::uninlined_format_args)]

use std::borrow::Cow;
use std::path::PathBuf;

use either::Either;
use crate::buffer::{ArrayBufferView, Buffer};
use crate::encoding::Encoder;
use crate::utils::{
    object::ObjectExt,
    result::{OptionExt, ResultExt},
};
use rquickjs::function::Opt;
use rquickjs::{Ctx, Error, Exception, FromJs, Null, Object, Result, Value};
use tokio::fs::File;
use tokio::io::{AsyncReadExt, AsyncSeekExt, AsyncWriteExt, SeekFrom};

use super::{read_file, Stats};

const DEFAULT_BUFFER_SIZE: usize = 16384;
const DEFAULT_ENCODING: &str = "utf8";

#[allow(dead_code)]
#[rquickjs::class]
#[derive(rquickjs::class::Trace, rquickjs::JsLifetime)]
pub struct FileHandle {
    #[qjs(skip_trace)]
    file: Option<File>,
    #[qjs(skip_trace)]
    path: PathBuf,
}

impl FileHandle {
    pub fn new(file: File, path: PathBuf) -> Self {
        Self {
            file: Some(file),
            path,
        }
    }

    fn file(&self, ctx: &Ctx<'_>) -> Result<&File> {
        self.file.as_ref().or_throw_msg(ctx, "FileHandle is closed")
    }

    fn file_mut(&mut self, ctx: &Ctx<'_>) -> Result<&mut File> {
        self.file.as_mut().or_throw_msg(ctx, "FileHandle is closed")
    }
}

#[rquickjs::methods(rename_all = "camelCase")]
impl FileHandle {
    #[allow(unused_variables)]
    async fn chmod(&self, ctx: Ctx<'_>, mode: u32) -> Result<()> {
        #[cfg(unix)]
        {
            use std::os::unix::fs::PermissionsExt;
            let perm = std::fs::Permissions::from_mode(mode);
            self.file(&ctx)?
                .set_permissions(perm)
                .await
                .or_throw_msg(&ctx, "Can't modify file permissions")?;
        }
        Ok(())
    }

    #[allow(unused_variables)]
    async fn chown(&self, ctx: Ctx<'_>, uid: u32, gid: u32) -> Result<()> {
        #[cfg(unix)]
        {
            let path = self.path.clone();
            tokio::task::spawn_blocking(move || {
                std::os::unix::fs::chown(&path, Some(uid), Some(gid))
            })
            .await
            .or_throw(&ctx)?
            .or_throw_msg(&ctx, "Can't modify file owner")?;
        }
        Ok(())
    }

    async fn close(&mut self) {
        if let Some(file) = self.file.take() {
            drop(file.into_std().await);
        }
    }

    async fn datasync(&self, ctx: Ctx<'_>) -> Result<()> {
        self.file(&ctx)?
            .sync_data()
            .await
            .or_throw_msg(&ctx, "Can't sync file data")?;
        Ok(())
    }

    #[qjs(get)]
    async fn fd(&self, ctx: Ctx<'_>) -> Result<i32> {
        #[cfg(unix)]
        {
            use std::os::fd::AsRawFd;
            Ok(self.file(&ctx)?.as_raw_fd())
        }
        #[cfg(windows)]
        {
            use std::os::windows::io::AsRawHandle;
            let handle = self.file(&ctx)?.as_raw_handle();
            Ok(handle as i32)
        }
        #[cfg(not(any(unix, windows)))]
        {
            Ok(0)
        }
    }

    async fn read<'js>(
        &mut self,
        ctx: Ctx<'js>,
        buffer_or_options: Opt<Either<ArrayBufferView<'js>, ReadOptions<'js>>>,
        options_or_offset: Opt<Either<ReadOptions<'js>, usize>>,
        length: Opt<usize>,
        position: Opt<Option<u64>>, // -1 is not supported
    ) -> Result<Object<'js>> {
        let options_1 = match buffer_or_options.0 {
            Some(Either::Left(buffer)) => ReadOptions {
                buffer: Some(buffer),
                ..Default::default()
            },
            Some(Either::Right(options)) => options,
            None => ReadOptions::default(),
        };
        let options_2 = match options_or_offset.0 {
            Some(Either::Left(options)) => options,
            Some(Either::Right(offset)) => ReadOptions {
                offset: Some(offset),
                ..Default::default()
            },
            None => ReadOptions::default(),
        };

        let mut buffer = options_1
            .buffer
            .or(options_2.buffer)
            .unwrap_or_else_ok(|| {
                ArrayBufferView::from_buffer(&ctx, Buffer::alloc(DEFAULT_BUFFER_SIZE))
            })?;
        let offset = options_1.offset.or(options_2.offset).unwrap_or(0);
        let length = options_1
            .length
            .or(options_2.length)
            .or(length.0)
            .unwrap_or_else(|| buffer.len() - offset);
        let position = options_1
            .position
            .or(options_2.position)
            .or(position.0.flatten());
        validate_length_offset(&ctx, length, offset, buffer.len())?;

        // It is not safe to pass the buffer from `ArrayBufferView` to `File::read`
        // since the read is done in a different thread and we cannot garantee
        // that multiple read calls are not done with the same buffer.
        // Ideally, we should make our own version of `BufReader` to reuse the buffer
        // instead of doing an allocation on each read.
        let mut buf = vec![0u8; length];
        let file = self.file_mut(&ctx)?;

        // Tokio doesn't offer an API for positional reads. This means we have
        // to seek to the position, read the file, and then seek back to the original
        // position. See https://github.com/tokio-rs/tokio/issues/699
        let mut cursor = None;
        if let Some(position) = position {
            cursor = Some(
                file.seek(SeekFrom::Current(0))
                    .await
                    .or_throw_msg(&ctx, "Can't get cursor")?,
            );
            file.seek(SeekFrom::Start(position))
                .await
                .or_throw_msg(&ctx, "Can't seek file")?;
        }

        let bytes_read = file
            .read(&mut buf)
            .await
            .or_throw_msg(&ctx, "Failed to read file")?;

        // Reset the file at the original position. If there is an error while
        // resetting the cursor, we close the file pre-emptively since future
        // reads would be invalid.
        if let Some(cursor) = cursor {
            if let Err(err) = file
                .seek(SeekFrom::Start(cursor))
                .await
                .or_throw_msg(&ctx, "Failed to reset cursor")
            {
                self.close().await;
                return Err(err);
            }
        }

        let dst_buf = buffer
            .as_bytes_mut()
            .or_throw_msg(&ctx, "Buffer is detached")?;
        dst_buf[offset..].copy_from_slice(&buf);

        let result = Object::new(ctx)?;
        result.set("bytesRead", bytes_read)?;
        result.set("buffer", buffer)?;
        Ok(result)
    }

    async fn read_file<'js>(
        &mut self,
        ctx: Ctx<'js>,
        options: Opt<Either<String, read_file::ReadFileOptions>>,
    ) -> Result<Value<'js>> {
        let size = self
            .file(&ctx)?
            .metadata()
            .await
            .map(|m| m.len() as usize)
            .ok();
        let mut bytes = Vec::new();
        bytes
            .try_reserve_exact(size.unwrap_or(0))
            .or_throw_msg(&ctx, "Out of memory")?;

        self.file_mut(&ctx)?
            .read_to_end(&mut bytes)
            .await
            .or_throw_msg(&ctx, "Failed to read file")?;
        read_file::handle_read_file_bytes(&ctx, options, bytes)
    }

    async fn stat(&self, ctx: Ctx<'_>) -> Result<Stats> {
        let metadata = self
            .file(&ctx)?
            .metadata()
            .await
            .or_throw_msg(&ctx, "Can't stat file")?;
        Ok(Stats::new(metadata))
    }

    async fn sync(&self, ctx: Ctx<'_>) -> Result<()> {
        self.file(&ctx)?
            .sync_all()
            .await
            .or_throw_msg(&ctx, "Can't sync file")
    }

    async fn truncate(&mut self, ctx: Ctx<'_>, len: Opt<u64>) -> Result<()> {
        let len = len.0.unwrap_or(0);
        self.file_mut(&ctx)?
            .set_len(len)
            .await
            .or_throw_msg(&ctx, "Can't truncate file")
    }

    // Setting times not supported in tokio
    // See https://github.com/tokio-rs/tokio/issues/6368
    // async fn utimes(&mut self,  ctx: Ctx<'_>, atime: Value<'_>, mtime: Value<'_>) -> Result<()>

    async fn write<'js>(
        &mut self,
        ctx: Ctx<'js>,
        buffer_or_string: Either<ArrayBufferView<'js>, String>,
        offset_or_options_or_position: Opt<Either<Either<usize, Null>, WriteOptions>>,
        length_or_encoding: Opt<Either<usize, String>>,
        position: Opt<Option<u64>>,
    ) -> Result<Object<'js>> {
        let mut options = match offset_or_options_or_position.0 {
            Some(Either::Left(Either::Left(offset_or_position))) => {
                if buffer_or_string.is_left() {
                    WriteOptions {
                        offset: Some(offset_or_position),
                        ..Default::default()
                    }
                } else {
                    WriteOptions::default()
                }
            },
            Some(Either::Right(options)) => options,
            _ => WriteOptions::default(),
        };
        if let Some(Either::Left(length)) = length_or_encoding.0 {
            options.length = Some(length);
        }

        let buffer = match &buffer_or_string {
            Either::Left(buffer) => {
                let buffer = buffer.as_bytes().or_throw_msg(&ctx, "Buffer is detached")?;
                Cow::Borrowed(buffer)
            },
            Either::Right(string) => {
                let encoding = length_or_encoding
                    .0
                    .and_then(|e| e.right())
                    .unwrap_or_else(|| DEFAULT_ENCODING.to_string());
                let buffer = Encoder::from_str(&encoding)
                    .and_then(|enc| enc.decode_from_string(string.clone()))
                    .or_throw(&ctx)?;
                Cow::Owned(buffer)
            },
        };

        let offset = options.offset.unwrap_or(0);
        let length = options.length.unwrap_or(buffer.len() - offset);
        let position = options.position.or(position.0.flatten());
        validate_length_offset(&ctx, length, offset, buffer.len())?;

        let file = self.file_mut(&ctx)?;

        // Tokio doesn't offer an API for positional writes. This means we have
        // to seek to the position, write to the file, and then seek back to the original
        // position. See https://github.com/tokio-rs/tokio/issues/699
        let mut cursor = None;
        if let Some(position) = position {
            cursor = Some(
                file.seek(SeekFrom::Current(0))
                    .await
                    .or_throw_msg(&ctx, "Can't get cursor")?,
            );
            file.seek(SeekFrom::Start(position))
                .await
                .or_throw_msg(&ctx, "Can't seek file")?;
        }

        file.write_all(&buffer[offset..length])
            .await
            .or_throw_msg(&ctx, "Failed to write to file")?;

        // Reset the file at the original position. If there is an error while
        // resetting the cursor, we close the file pre-emptively since future
        // writes would be invalid.
        if let Some(cursor) = cursor {
            if let Err(err) = file
                .seek(SeekFrom::Start(cursor))
                .await
                .or_throw_msg(&ctx, "Failed to reset cursor")
            {
                self.close().await;
                return Err(err);
            }
        }

        let result = Object::new(ctx)?;
        result.set("bytesWritten", length)?;
        result.set("buffer", buffer_or_string)?;
        Ok(result)
    }

    async fn write_file<'js>(
        &mut self,
        ctx: Ctx<'js>,
        data: Either<ArrayBufferView<'js>, String>,
        options_or_encoding: Opt<Either<WriteFileOptions, String>>,
    ) -> Result<()> {
        let file = self.file_mut(&ctx)?;

        // Always overwrite the whole file
        file.set_len(0)
            .await
            .or_throw_msg(&ctx, "Failed to truncate file")?;

        let encoding = match options_or_encoding.0 {
            Some(Either::Left(options)) => options.encoding,
            Some(Either::Right(encoding)) => Some(encoding),
            _ => None,
        }
        .unwrap_or_else(|| DEFAULT_ENCODING.to_string());

        let buffer = match &data {
            Either::Left(buffer) => {
                let buffer = buffer.as_bytes().or_throw_msg(&ctx, "Buffer is detached")?;
                Cow::Borrowed(buffer)
            },
            Either::Right(string) => {
                let buffer = Encoder::from_str(&encoding)
                    .and_then(|enc| enc.decode_from_string(string.clone()))
                    .or_throw(&ctx)?;
                Cow::Owned(buffer)
            },
        };

        file.write_all(&buffer)
            .await
            .or_throw_msg(&ctx, "Failed to write to file")?;
        Ok(())
    }
}

fn validate_length_offset(
    ctx: &Ctx<'_>,
    length: usize,
    offset: usize,
    buffer_length: usize,
) -> Result<()> {
    if offset > buffer_length {
        return Err(Exception::throw_range(
            ctx,
            &format!("offset ({}) <= {}", offset, buffer_length),
        ));
    }
    if length > buffer_length - offset {
        return Err(Exception::throw_range(
            ctx,
            &format!("length ({}) <= {}", length, buffer_length - offset),
        ));
    }
    Ok(())
}

#[derive(Default)]
struct ReadOptions<'js> {
    buffer: Option<ArrayBufferView<'js>>,
    offset: Option<usize>,
    length: Option<usize>,
    position: Option<u64>,
}

impl<'js> FromJs<'js> for ReadOptions<'js> {
    fn from_js(_ctx: &Ctx<'js>, value: Value<'js>) -> Result<Self> {
        let ty_name = value.type_name();
        let obj = value
            .as_object()
            .ok_or(Error::new_from_js(ty_name, "Object"))?;

        let buffer = obj.get_optional::<_, ArrayBufferView<'js>>("buffer")?;
        let offset = obj.get_optional::<_, usize>("offset")?;
        let length = obj.get_optional::<_, usize>("length")?;
        let position = obj.get_optional::<_, u64>("position")?;

        Ok(Self {
            buffer,
            offset,
            length,
            position,
        })
    }
}

#[derive(Default)]
struct WriteOptions {
    offset: Option<usize>,
    length: Option<usize>,
    position: Option<u64>,
}

impl<'js> FromJs<'js> for WriteOptions {
    fn from_js(_ctx: &Ctx<'js>, value: Value<'js>) -> Result<Self> {
        let ty_name = value.type_name();
        let obj = value
            .as_object()
            .ok_or(Error::new_from_js(ty_name, "Object"))?;

        let offset = obj.get_optional::<_, usize>("offset")?;
        let length = obj.get_optional::<_, usize>("length")?;
        let position = obj.get_optional::<_, u64>("position")?;

        Ok(Self {
            offset,
            length,
            position,
        })
    }
}

#[derive(Default)]
struct WriteFileOptions {
    encoding: Option<String>,
}

impl<'js> FromJs<'js> for WriteFileOptions {
    fn from_js(_ctx: &Ctx<'js>, value: Value<'js>) -> Result<Self> {
        let ty_name = value.type_name();
        let obj = value
            .as_object()
            .ok_or(Error::new_from_js(ty_name, "Object"))?;

        let encoding = obj.get_optional::<_, String>("encoding")?;

        Ok(Self { encoding })
    }
}