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//
// Copyright (c) 2017, 2020 ADLINK Technology Inc.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License 2.0 which is available at
// http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
//
// Contributors:
//   ADLINK zenoh team, <zenoh@adlink-labs.tech>
//
use super::{ArcSlice, RBuf, WBuf};
use crate::core::{PeerId, ZInt, ZINT_MAX_BYTES};
use crate::link::Locator;

macro_rules! read_zint {
    ($buf:expr, $res:ty) => {
        let mut v: $res = 0;
        let mut b = $buf.read()?;
        let mut i = 0;
        let mut k = ZINT_MAX_BYTES;
        while b > 0x7f && k > 0 {
            v |= ((b & 0x7f) as $res) << i;
            i += 7;
            b = $buf.read()?;
            k -= 1;
        }
        if k > 0 {
            v |= ((b & 0x7f) as $res) << i;
            return Some(v);
        } else {
            log::trace!("Invalid ZInt (larget than ZInt max value: {})", ZInt::MAX);
            return None;
        }
    };
}

impl RBuf {
    pub fn read_zint(&mut self) -> Option<ZInt> {
        read_zint!(self, ZInt);
    }

    pub fn read_zint_as_u64(&mut self) -> Option<u64> {
        read_zint!(self, u64);
    }

    pub fn read_zint_as_usize(&mut self) -> Option<usize> {
        read_zint!(self, usize);
    }

    // Same as read_bytes but with array length before the bytes.
    pub fn read_bytes_array(&mut self) -> Option<Vec<u8>> {
        let len = self.read_zint_as_usize()?;
        let mut buf = vec![0; len];
        if self.read_bytes(buf.as_mut_slice()) {
            Some(buf)
        } else {
            None
        }
    }

    // Same as read_bytes_array but 0 copy on RBuf.
    pub fn read_rbuf(&mut self) -> Option<RBuf> {
        let len = self.read_zint_as_usize()?;
        let mut rbuf = RBuf::new();
        if self.read_into_rbuf(&mut rbuf, len) {
            Some(rbuf)
        } else {
            None
        }
    }

    pub fn read_string(&mut self) -> Option<String> {
        let bytes = self.read_bytes_array()?;
        Some(String::from(String::from_utf8_lossy(&bytes)))
    }

    pub fn read_peerid(&mut self) -> Option<PeerId> {
        let size = self.read_zint_as_usize()?;
        if size > PeerId::MAX_SIZE {
            log::trace!("Reading a PeerId size that exceed 16 bytes: {}", size);
            return None;
        }
        let mut id = [0u8; PeerId::MAX_SIZE];
        if self.read_bytes(&mut id[..size]) {
            Some(PeerId::new(size, id))
        } else {
            None
        }
    }

    pub fn read_locator(&mut self) -> Option<Locator> {
        self.read_string()?.parse().ok()
    }

    pub fn read_locators(&mut self) -> Option<Vec<Locator>> {
        let len = self.read_zint()?;
        let mut vec: Vec<Locator> = Vec::new();
        for _ in 0..len {
            vec.push(self.read_locator()?);
        }
        Some(vec)
    }
}

macro_rules! write_zint {
    ($buf:expr, $val:expr) => {
        let mut c = $val;
        let mut b: u8 = (c & 0xff) as u8;
        while c > 0x7f && $buf.write(b | 0x80) {
            c >>= 7;
            b = (c & 0xff) as u8;
        }
        return $buf.write(b);
    };
}

impl WBuf {
    /// This the traditional VByte encoding, in which an arbirary integer
    /// is encoded as a sequence of 7 bits integers
    pub fn write_zint(&mut self, v: ZInt) -> bool {
        write_zint!(self, v);
    }

    pub fn write_u64_as_zint(&mut self, v: u64) -> bool {
        write_zint!(self, v);
    }

    pub fn write_usize_as_zint(&mut self, v: usize) -> bool {
        write_zint!(self, v);
    }

    // Same as write_bytes but with array length before the bytes.
    pub fn write_bytes_array(&mut self, s: &[u8]) -> bool {
        self.write_usize_as_zint(s.len()) && self.write_bytes(s)
    }

    pub fn write_string(&mut self, s: &str) -> bool {
        self.write_usize_as_zint(s.len()) && self.write_bytes(s.as_bytes())
    }

    // Similar than write_bytes_array but zero-copy as slice is shared
    pub fn write_bytes_slice(&mut self, slice: &ArcSlice) -> bool {
        self.write_usize_as_zint(slice.len()) && self.write_slice(slice.clone())
    }

    pub fn write_peerid(&mut self, pid: &PeerId) -> bool {
        self.write_bytes_array(pid.as_slice())
    }

    pub fn write_locator(&mut self, locator: &Locator) -> bool {
        zcheck!(self.write_string(&locator.to_string()));
        true
    }

    pub fn write_locators(&mut self, locators: &[Locator]) -> bool {
        zcheck!(self.write_usize_as_zint(locators.len()));
        for l in locators {
            zcheck!(self.write_locator(&l));
        }

        true
    }

    // Similar than write_bytes_array but zero-copy as RBuf contains slices that are shared
    pub fn write_rbuf(&mut self, rbuf: &RBuf) -> bool {
        if self.write_usize_as_zint(rbuf.len()) {
            self.write_rbuf_slices(&rbuf)
        } else {
            false
        }
    }

    // Writes all the slices of a given RBuf
    pub fn write_rbuf_slices(&mut self, rbuf: &RBuf) -> bool {
        for slice in rbuf.get_slices() {
            if !self.write_slice(slice.clone()) {
                return false;
            }
        }
        true
    }
}