// Copyright (c) 2013-2015 Sandstorm Development Group, Inc. and contributors
// Licensed under the MIT License:
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// THE SOFTWARE.

//! # Cap'n Proto Runtime Library
//!
//! [Cap'n Proto](https://capnproto.org) is an extremely efficient protocol for
//! sharing data and capabilities.
//!
//! The Rust implementation is split into three separate crates.
//!
//! Code generation is handled by [capnpc-rust](https://github.com/dwrensha/capnpc-rust).
//!
//! The present crate is the runtime library required by that generated code. It is hosted on Github
//! [here](https://github.com/dwrensha/capnproto-rust).
//!
//! [capnp-rpc-rust](https://github.com/dwrensha/capnp-rpc-rust) is an implementation of a
//! distributed object-capability layer.

#![allow(raw_pointer_derive)]

#![crate_name="capnp"]
#![crate_type = "lib"]

extern crate byteorder;

#[cfg(test)]
extern crate quickcheck;

pub mod any_pointer;
pub mod capability;
pub mod data;
pub mod data_list;
pub mod enum_list;
pub mod list_list;
pub mod message;
pub mod primitive_list;
pub mod private;
pub mod serialize;
pub mod serialize_packed;
pub mod struct_list;
pub mod text;
pub mod text_list;
pub mod traits;

mod util;

/// Eight bytes of memory with opaque interior.
///
/// This type is used to ensure that the data of a message is properly aligned.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[repr(C)]
pub struct Word(u64);

impl Word {
    /// Does this, but faster:
    /// `::std::iter::repeat(Word(0)).take(length).collect()`
    pub fn allocate_zeroed_vec(length: usize) -> Vec<Word> {
        let mut result : Vec<Word> = Vec::with_capacity(length);
        unsafe {
            result.set_len(length);
            let p : *mut u8 = result.as_mut_ptr() as *mut u8;
            ::std::ptr::write_bytes(p, 0u8, length * ::std::mem::size_of::<Word>());
        }
        result
    }

    pub fn bytes_to_words<'a>(bytes: &'a [u8]) -> &'a [Word] {
        unsafe {
            ::std::slice::from_raw_parts(bytes.as_ptr() as *const Word, bytes.len() / 8)
        }
    }

    pub fn words_to_bytes<'a>(words: &'a [Word]) -> &'a [u8] {
        unsafe {
            ::std::slice::from_raw_parts(words.as_ptr() as *const u8, words.len() * 8)
        }
    }

    pub fn words_to_bytes_mut<'a>(words: &'a mut [Word]) -> &'a mut [u8] {
        unsafe {
            ::std::slice::from_raw_parts_mut(words.as_mut_ptr() as *mut u8, words.len() * 8)
        }
    }

    #[cfg(test)]
    pub fn from(n: u64) -> Word {
        Word(n)
    }
}

#[cfg(test)]
impl quickcheck::Arbitrary for Word {
    fn arbitrary<G: quickcheck::Gen>(g: &mut G) -> Word {
        Word(quickcheck::Arbitrary::arbitrary(g))
    }
    fn shrink(&self) -> Box<Iterator<Item=Word>+'static> {
        Box::new(quickcheck::Arbitrary::shrink(&self.0).map(|value| Word(value)))
    }
}

/// Size of a message. Every generated struct has a method `.total_size()` that returns this.
#[derive(Clone, Copy, PartialEq)]
pub struct MessageSize {
    pub word_count : u64,

    /// Size of the capability table.
    pub cap_count : u32
}

impl MessageSize {
    pub fn plus_eq(&mut self, other : MessageSize) {
        self.word_count += other.word_count;
        self.cap_count += other.cap_count;
    }
}

/// An enum value or union discriminant that was not found among those defined in a schema.
#[derive(PartialEq, Clone, Copy, Debug)]
pub struct NotInSchema(pub u16);

impl ::std::fmt::Display for NotInSchema {
    fn fmt(&self, fmt : &mut ::std::fmt::Formatter) -> ::std::result::Result<(), ::std::fmt::Error> {
        write!(fmt, "Enum value or union discriminant {} was not present in the schema.", self.0)
    }
}

impl ::std::error::Error for NotInSchema {
    fn description(&self) -> &str {
        "Enum value or union disriminant was not present in schema."
    }
}

/// Because messages are lazily validated, the return type of any method that reads a pointer field
/// must be wrapped in a Result.
pub type Result<T> = ::std::result::Result<T, Error>;

/// Things that can go wrong when you read a message.
#[derive(Debug)]
pub enum Error {
    Decode { description : &'static str,
             detail : Option<String> },
    Io(std::io::Error),
}

impl Error {
    pub fn new_decode_error(description : &'static str, detail : Option<String>) -> Error {
        Error::Decode { description : description, detail : detail}
    }
}

impl ::std::convert::From<::std::io::Error> for Error {
    fn from(err : ::std::io::Error) -> Error {
        Error::Io(err)
    }
}

impl ::std::convert::From<NotInSchema> for Error {
    fn from(e : NotInSchema) -> Error {
        Error::new_decode_error("Enum value or union discriminant was not present in schema.",
                                Some(format!("value : {}", e.0)))
    }
}

impl ::std::fmt::Display for Error {
    fn fmt(&self, fmt : &mut ::std::fmt::Formatter) -> ::std::result::Result<(), ::std::fmt::Error> {
        match *self {
            Error::Decode { ref description, detail : Some(ref detail) } => {
                write!(fmt, "{} {}", description, detail)
            },
            Error::Decode { ref description, .. } => write!(fmt, "{}", description),
            Error::Io(ref io) => io.fmt(fmt),
        }
    }
}

impl ::std::error::Error for Error {
    fn description(&self) -> &str {
        match *self {
            Error::Decode { ref description, .. } => description,
            Error::Io(ref io) => ::std::error::Error::description(io),
        }
    }
    fn cause(&self) -> Option<&::std::error::Error> {
        match *self {
            Error::Decode { .. } => None,
            Error::Io(ref io) => io.cause(),
        }
    }
}

/// Helper struct that allows `MessageBuilder::get_segments_for_output()` to avoid heap allocations
/// in the single-segment case.
pub enum OutputSegments<'a> {
    #[doc(hidden)]
    SingleSegment([&'a [Word]; 1]),

    #[doc(hidden)]
    MultiSegment(Vec<&'a [Word]>),
}

impl <'a> ::std::ops::Deref for OutputSegments<'a> {
    type Target = [&'a [Word]];
    fn deref<'b>(&'b self) -> &'b [&'a [Word]] {
        match self {
            &OutputSegments::SingleSegment(ref s) => {
                s
            }
            &OutputSegments::MultiSegment(ref v) => {
                &*v
            }
        }
    }
}