/*
 * Licensed to Elasticsearch B.V. under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch B.V. 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.
 */
//! HTTP request components

use crate::error::Error;
use bytes::buf::BufMutExt;
use bytes::{BufMut, Bytes, BytesMut};
use percent_encoding::AsciiSet;
use serde::Serialize;

// similar to percent-encoding's NON_ALPHANUMERIC AsciiSet, but with some characters removed
pub(crate) const PARTS_ENCODED: &AsciiSet = &percent_encoding::NON_ALPHANUMERIC
    .remove(b'_')
    .remove(b'-')
    .remove(b'.')
    .remove(b',')
    .remove(b'*');

/// Body of an API call.
///
/// Some Elasticsearch APIs accept a body as part of the API call. Most APIs
/// expect JSON, however, there are some APIs that expect newline-delimited JSON (NDJSON).
/// The [Body] trait allows modelling different API body implementations.
pub trait Body {
    /// An existing immutable buffer that can be used to avoid
    /// having to write to another buffer that will then be written to the request stream.
    ///
    /// If this method returns `Some`, the bytes must be the same as
    /// those that would be written by [Body::write].
    fn bytes(&self) -> Option<Bytes> {
        None
    }

    /// Write to a buffer that will be written to the request stream
    fn write(&self, bytes: &mut BytesMut) -> Result<(), Error>;
}

impl<'a, B: ?Sized> Body for &'a B
where
    B: Body,
{
    fn bytes(&self) -> Option<Bytes> {
        (**self).bytes()
    }

    fn write(&self, bytes: &mut BytesMut) -> Result<(), Error> {
        (**self).write(bytes)
    }
}

/// A JSON body of an API call.
pub struct JsonBody<T>(pub(crate) T);

impl<T> JsonBody<T>
where
    T: Serialize,
{
    /// Creates a new instance of [JsonBody] for a type `T` that implements [serde::Serialize]
    pub fn new(t: T) -> Self {
        Self(t)
    }
}

impl<T> From<T> for JsonBody<T>
where
    T: Serialize,
{
    /// Creates a new instance of [JsonBody] from a type `T` that implements [serde::Serialize]
    fn from(t: T) -> Self {
        JsonBody(t)
    }
}

impl<T> Body for JsonBody<T>
where
    T: Serialize,
{
    fn write(&self, bytes: &mut BytesMut) -> Result<(), Error> {
        let writer = bytes.writer();
        serde_json::to_writer(writer, &self.0)?;

        Ok(())
    }
}

/// A Newline-delimited body of an API call
pub struct NdBody<T>(pub(crate) Vec<T>);

impl<T> NdBody<T>
where
    T: Body,
{
    /// Creates a new instance of [NdBody], for a collection of `T` that implement [Body].
    ///
    /// Accepts `T` that implement [Body] as opposed to [serde::Serialize], because each `T`
    /// itself may need to serialize to newline delimited.
    pub fn new(b: Vec<T>) -> Self {
        Self(b)
    }
}

impl<T> Body for NdBody<T>
where
    T: Body,
{
    fn write(&self, bytes: &mut BytesMut) -> Result<(), Error> {
        for line in &self.0 {
            line.write(bytes)?;
            // only write a newline if the T impl does not
            if let Some(b) = bytes.last() {
                if b != &(b'\n') {
                    bytes.put_u8(b'\n');
                }
            }
        }
        Ok(())
    }
}

impl Body for Bytes {
    fn bytes(&self) -> Option<Bytes> {
        Some(self.clone())
    }

    fn write(&self, bytes: &mut BytesMut) -> Result<(), Error> {
        self.as_ref().write(bytes)
    }
}

impl Body for BytesMut {
    fn bytes(&self) -> Option<Bytes> {
        Some(self.clone().freeze())
    }

    fn write(&self, bytes: &mut BytesMut) -> Result<(), Error> {
        self.as_ref().write(bytes)
    }
}

impl Body for Vec<u8> {
    fn write(&self, bytes: &mut BytesMut) -> Result<(), Error> {
        self.as_slice().write(bytes)
    }
}

impl<'a> Body for &'a [u8] {
    fn write(&self, bytes: &mut BytesMut) -> Result<(), Error> {
        bytes.reserve(self.len());
        bytes.put_slice(*self);
        Ok(())
    }
}

impl Body for String {
    fn write(&self, bytes: &mut BytesMut) -> Result<(), Error> {
        self.as_bytes().write(bytes)
    }
}

impl<'a> Body for &'a str {
    fn write(&self, bytes: &mut BytesMut) -> Result<(), Error> {
        self.as_bytes().write(bytes)
    }
}

impl Body for () {
    fn write(&self, _bytes: &mut BytesMut) -> Result<(), Error> {
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use crate::http::request::{Body, JsonBody, NdBody};
    use bytes::BytesMut;
    use serde_json::json;

    #[test]
    fn serialize_into_jsonbody_writes_to_bytes() -> Result<(), failure::Error> {
        let mut bytes = BytesMut::new();
        let body: JsonBody<_> = json!({"foo":"bar","baz":1}).into();
        let _ = body.write(&mut bytes)?;
        // NOTE: serde_json writes properties lexicographically
        assert_eq!(b"{\"baz\":1,\"foo\":\"bar\"}", &bytes[..]);

        Ok(())
    }

    #[test]
    fn bodies_into_ndbody_writes_to_bytes() -> Result<(), failure::Error> {
        let mut bytes = BytesMut::new();
        let mut bodies: Vec<JsonBody<_>> = Vec::with_capacity(2);
        bodies.push(json!({"item":1}).into());
        bodies.push(json!({"item":2}).into());

        let body = NdBody(bodies);
        let _ = body.write(&mut bytes)?;
        assert_eq!(b"{\"item\":1}\n{\"item\":2}\n", &bytes[..]);

        Ok(())
    }

    #[test]
    fn bytes_body_writes_to_bytes_mut() -> Result<(), failure::Error> {
        let mut bytes_mut = BytesMut::with_capacity(21);
        let bytes = bytes::Bytes::from(&b"{\"foo\":\"bar\",\"baz\":1}"[..]);
        let _ = bytes.write(&mut bytes_mut)?;
        assert_eq!(&bytes[..], &bytes_mut[..]);

        Ok(())
    }

    #[test]
    fn bytes_body_returns_usable_buf() -> Result<(), failure::Error> {
        let mut bytes_mut = BytesMut::with_capacity(21);
        let buf = bytes::Bytes::from(&b"{\"foo\":\"bar\",\"baz\":1}"[..]);

        let bytes = buf.bytes().expect("bytes always returns Some");
        let _ = buf.write(&mut bytes_mut)?;
        assert_eq!(&buf[..], &bytes_mut[..]);
        assert_eq!(&bytes[..], &bytes_mut[..]);

        Ok(())
    }

    #[test]
    fn vec_body_writes_to_bytes_mut() -> Result<(), failure::Error> {
        let mut bytes_mut = BytesMut::with_capacity(21);
        let bytes = b"{\"foo\":\"bar\",\"baz\":1}".to_vec();
        let _ = bytes.write(&mut bytes_mut)?;
        assert_eq!(&bytes[..], &bytes_mut[..]);

        Ok(())
    }

    #[test]
    fn bytes_slice_body_writes_to_bytes_mut() -> Result<(), failure::Error> {
        let mut bytes_mut = BytesMut::with_capacity(21);
        let bytes: &'static [u8] = b"{\"foo\":\"bar\",\"baz\":1}";
        let _ = bytes.write(&mut bytes_mut)?;
        assert_eq!(&bytes[..], &bytes_mut[..]);

        Ok(())
    }

    #[test]
    fn string_body_writes_to_bytes_mut() -> Result<(), failure::Error> {
        let mut bytes_mut = BytesMut::with_capacity(21);
        let s = String::from("{\"foo\":\"bar\",\"baz\":1}");
        let _ = s.write(&mut bytes_mut)?;
        assert_eq!(s.as_bytes(), &bytes_mut[..]);

        Ok(())
    }

    #[test]
    fn string_slice_body_writes_to_bytes_mut() -> Result<(), failure::Error> {
        let mut bytes_mut = BytesMut::with_capacity(21);
        let s: &'static str = "{\"foo\":\"bar\",\"baz\":1}";
        let _ = s.write(&mut bytes_mut)?;
        assert_eq!(s.as_bytes(), &bytes_mut[..]);

        Ok(())
    }
}