//! Object types defined in the Bitmessage protocol.

use std::{
    convert::{TryFrom, TryInto},
    fmt,
    io::{self, Cursor, Read, Write},
};

use crate::{
    __impl_index, __impl_u8_array,
    address::{Address, FromPublicKeysError},
    content, crypto,
    io::{LenBm, ReadFrom, SizedReadFrom, WriteTo},
    message,
    net::{Addr, AddrExt, OnionV3Addr, ParseOnionV3AddrError, SocketAddrExt},
    priv_util::ToHexString,
    time::Time,
    var_type::VarInt,
};

pub use crate::stream::StreamNumber;

/// Represents type of object such as public key or one-to-one message.
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
pub struct ObjectType(u32);

impl ObjectType {
    /// Constructs an object type from a value.
    pub const fn new(value: u32) -> Self {
        Self(value)
    }

    /// Returns the value as `u32`.
    pub fn as_u32(self) -> u32 {
        self.0
    }
}

impl fmt::Display for ObjectType {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)
    }
}

impl From<u32> for ObjectType {
    fn from(value: u32) -> Self {
        Self(value)
    }
}

impl WriteTo for ObjectType {
    fn write_to(&self, w: &mut dyn Write) -> io::Result<()> {
        self.0.write_to(w)
    }
}

impl ReadFrom for ObjectType {
    fn read_from(r: &mut dyn Read) -> io::Result<Self>
    where
        Self: Sized,
    {
        Ok(Self(u32::read_from(r)?))
    }
}

impl LenBm for ObjectType {
    fn len_bm(&self) -> usize {
        self.0.len_bm()
    }
}

/// A version number used in Bitmessage objects.
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
pub struct ObjectVersion(VarInt);

impl fmt::Display for ObjectVersion {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)
    }
}

impl ObjectVersion {
    /// Constructs an object version from a value.
    pub fn new(value: u64) -> Self {
        Self(value.into())
    }

    /// Returns the value as `u64`.
    pub fn as_u64(self) -> u64 {
        self.0.as_u64()
    }
}

impl From<u64> for ObjectVersion {
    fn from(value: u64) -> Self {
        Self(value.into())
    }
}

impl WriteTo for ObjectVersion {
    fn write_to(&self, w: &mut dyn Write) -> io::Result<()> {
        self.0.write_to(w)
    }
}

impl ReadFrom for ObjectVersion {
    fn read_from(r: &mut dyn Read) -> io::Result<Self>
    where
        Self: Sized,
    {
        Ok(Self(VarInt::read_from(r)?))
    }
}

impl LenBm for ObjectVersion {
    fn len_bm(&self) -> usize {
        self.0.len_bm()
    }
}

/// The header structure of Bitmessage objects.
#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
pub struct Header {
    expires_time: Time,
    object_type: ObjectType,
    version: ObjectVersion,
    stream_number: StreamNumber,
}

impl Header {
    /// Constructs an object header from the specified parameters.
    pub fn new(
        expires_time: Time,
        object_type: ObjectType,
        version: ObjectVersion,
        stream_number: StreamNumber,
    ) -> Self {
        Self {
            expires_time,
            object_type,
            version,
            stream_number,
        }
    }

    /// Returns the expires time.
    pub fn expires_time(&self) -> Time {
        self.expires_time
    }

    /// Returns the object type.
    pub fn object_type(&self) -> ObjectType {
        self.object_type
    }

    /// Returns the object version.
    pub fn version(&self) -> ObjectVersion {
        self.version
    }

    /// Returns the stream number.
    pub fn stream_number(&self) -> StreamNumber {
        self.stream_number
    }
}

impl WriteTo for Header {
    fn write_to(&self, w: &mut dyn Write) -> io::Result<()> {
        self.expires_time.write_to(w)?;
        self.object_type.write_to(w)?;
        self.version.write_to(w)?;
        self.stream_number.write_to(w)?;
        Ok(())
    }
}

impl ReadFrom for Header {
    fn read_from(r: &mut dyn Read) -> io::Result<Self>
    where
        Self: Sized,
    {
        Ok(Self {
            expires_time: Time::read_from(r)?,
            object_type: ObjectType::read_from(r)?,
            version: ObjectVersion::read_from(r)?,
            stream_number: StreamNumber::read_from(r)?,
        })
    }
}

impl LenBm for Header {
    fn len_bm(&self) -> usize {
        self.expires_time.len_bm()
            + self.object_type.len_bm()
            + self.version.len_bm()
            + self.stream_number.len_bm()
    }
}

#[test]
fn test_header_write_to() {
    let test = Header::new(
        0x0123_4567_89ab_cdef.into(),
        2.into(),
        3u64.into(),
        1u32.into(),
    );
    let mut bytes = Vec::new();
    test.write_to(&mut bytes).unwrap();
    let expected = [
        0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef, 0x00, 0x00, 0x00, 0x02, 3, 1,
    ];
    assert_eq!(bytes, expected);
}

#[test]
fn test_header_read_from() {
    use std::io::Cursor;

    let mut bytes = Cursor::new([
        0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef, 0x00, 0x00, 0x00, 0x02, 3, 1,
    ]);
    let test = Header::read_from(&mut bytes).unwrap();
    let expected = Header::new(
        0x0123_4567_89ab_cdef.into(),
        2.into(),
        3u64.into(),
        1u32.into(),
    );
    assert_eq!(test, expected);
}

/// Known types of Bitmessage objects.
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
pub enum ObjectKind {
    /// getpubkey object type.
    Getpubkey,
    /// pubkey object type.
    Pubkey,
    /// msg object type.
    Msg,
    /// broadcast object type.
    Broadcast,
    /// onionpeer object type.
    Onionpeer,
    //I2p,
    //Addr,
}

const OBJECT_GETPUBKEY: u32 = 0;
const OBJECT_PUBKEY: u32 = 1;
const OBJECT_MSG: u32 = 2;
const OBJECT_BROADCAST: u32 = 3;
const OBJECT_ONIONPEER: u32 = 0x74_6f72;
//const OBJECT_I2P: u32 = 0x493250;
//const OBJECT_ADDR: u32 = 0x61646472;

/// The error type returned when a conversion from a Bitmessage object type
/// to a known object type fails.
///
/// This error is used as the error type for the `TryFrom` implementation
/// for `ObjectKind`.
///
/// The source object type is returned as a payload of this error type.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct TryFromObjectTypeError(ObjectType);

impl fmt::Display for TryFromObjectTypeError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "unknown object type {}", self.0)
    }
}

impl std::error::Error for TryFromObjectTypeError {}

impl TryFrom<ObjectType> for ObjectKind {
    type Error = TryFromObjectTypeError;

    fn try_from(t: ObjectType) -> Result<Self, <Self as TryFrom<ObjectType>>::Error> {
        match t.as_u32() {
            OBJECT_GETPUBKEY => Ok(Self::Getpubkey),
            OBJECT_PUBKEY => Ok(Self::Pubkey),
            OBJECT_MSG => Ok(Self::Msg),
            OBJECT_BROADCAST => Ok(Self::Broadcast),
            OBJECT_ONIONPEER => Ok(Self::Onionpeer),
            _ => Err(TryFromObjectTypeError(t)),
        }
    }
}

impl From<ObjectKind> for ObjectType {
    fn from(kind: ObjectKind) -> Self {
        match kind {
            ObjectKind::Getpubkey => OBJECT_GETPUBKEY.into(),
            ObjectKind::Pubkey => OBJECT_PUBKEY.into(),
            ObjectKind::Msg => OBJECT_MSG.into(),
            ObjectKind::Broadcast => OBJECT_BROADCAST.into(),
            ObjectKind::Onionpeer => OBJECT_ONIONPEER.into(),
        }
    }
}

/// A version 4 broadcast object.
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub struct BroadcastV4 {
    encrypted: Vec<u8>,
}

impl BroadcastV4 {
    /// Returns the reference to the encrypted content of this broadcast object.
    pub fn encrypted(&self) -> &[u8] {
        &self.encrypted
    }
}

impl WriteTo for BroadcastV4 {
    fn write_to(&self, w: &mut dyn Write) -> io::Result<()> {
        self.encrypted.write_to(w)?;
        Ok(())
    }
}

impl SizedReadFrom for BroadcastV4 {
    fn sized_read_from(r: &mut dyn Read, len: usize) -> io::Result<Self>
    where
        Self: Sized,
    {
        let encrypted = Vec::<u8>::sized_read_from(r, len)?;
        Ok(Self { encrypted })
    }
}

/// A tag for a version 5 broadcast object.
#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
pub struct Tag([u8; 32]);

impl Tag {
    /// Creates 160 bit hash object from byte array.
    pub fn new(value: [u8; 32]) -> Self {
        Self(value)
    }
}

__impl_u8_array!(Tag);
__impl_index!(Tag, 0, u8);

impl WriteTo for Tag {
    fn write_to(&self, w: &mut dyn Write) -> io::Result<()> {
        self.0.write_to(w)
    }
}

impl ReadFrom for Tag {
    fn read_from(r: &mut dyn Read) -> io::Result<Self>
    where
        Self: Sized,
    {
        Ok(Self(<[u8; 32]>::read_from(r)?))
    }
}

impl LenBm for Tag {
    fn len_bm(&self) -> usize {
        self.0.len()
    }
}

/// A version 5 broadcast object.
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub struct BroadcastV5 {
    tag: Tag,
    encrypted: Vec<u8>,
}

impl BroadcastV5 {
    /// Returns the reference to the tag of this broadcast object.
    pub fn tag(&self) -> &Tag {
        &self.tag
    }

    /// Returns the reference to the encrypted content of this broadcast object.
    pub fn encrypted(&self) -> &[u8] {
        &self.encrypted
    }
}

impl WriteTo for BroadcastV5 {
    fn write_to(&self, w: &mut dyn Write) -> io::Result<()> {
        self.tag.write_to(w)?;
        self.encrypted.write_to(w)?;
        Ok(())
    }
}

impl SizedReadFrom for BroadcastV5 {
    fn sized_read_from(r: &mut dyn Read, len: usize) -> io::Result<Self>
    where
        Self: Sized,
    {
        let tag = Tag::read_from(r)?;
        let encrypted = Vec::<u8>::sized_read_from(r, len - tag.len_bm())?;
        Ok(Self { tag, encrypted })
    }
}

/// This error indicates
/// that the decryption failed.
#[derive(Debug)]
pub enum DecryptError {
    /// A standard I/O error was caught during decrypting a message.
    /// The actual error caught is returned as a payload of this variant.
    IoError(io::Error),
    /// A decryption error was caught during decrypting a message.
    /// The actual error caught is returned as a payload of this variant.
    DecryptError(crypto::DecryptError),
    /// Indicates that the stream numbers from the header and the content does not match.
    StreamsNotMatch {
        /// The stream number from the header.
        headers: StreamNumber,
        /// The stream number from the content.
        contents: StreamNumber,
    },
    /// An error was caught during conversion from public keys to an address.
    /// The actual error caught is returned as a payload of this variant.
    FromPublicKeysError(FromPublicKeysError),
    /// Indicates that the address reconstructed from the message content does not match the sender address.
    /// The expected and the actual addressess are returned as payloads of this variant.
    InvalidAddress {
        /// The expected address.
        expected: Address,
        /// The actual address.
        actual: Address,
    },
    /// An error was caught during verification of the signature.
    /// The actual error caught is returned as a payload of this variant.
    VerifyError(crypto::VerifyError),
}

impl fmt::Display for DecryptError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::IoError(err) => err.fmt(f),
            Self::DecryptError(err) => err.fmt(f),
            Self::StreamsNotMatch { headers, contents } => write!(
                f,
                "streams not match: header's is {}, but content's is {}",
                headers, contents
            ),
            Self::FromPublicKeysError(err) => err.fmt(f),
            Self::InvalidAddress { expected, actual } => write!(
                f,
                "address is expected to be {}, but actual is {}",
                expected, actual
            ),
            Self::VerifyError(err) => err.fmt(f),
        }
    }
}

impl std::error::Error for DecryptError {}

impl From<io::Error> for DecryptError {
    fn from(err: io::Error) -> Self {
        Self::IoError(err)
    }
}

impl From<crypto::DecryptError> for DecryptError {
    fn from(err: crypto::DecryptError) -> Self {
        Self::DecryptError(err)
    }
}

impl From<FromPublicKeysError> for DecryptError {
    fn from(err: FromPublicKeysError) -> Self {
        Self::FromPublicKeysError(err)
    }
}

impl From<crypto::VerifyError> for DecryptError {
    fn from(err: crypto::VerifyError) -> Self {
        Self::VerifyError(err)
    }
}

/// A broadcast object.
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub enum Broadcast {
    /// A version 4 broadcast object.
    V4(BroadcastV4),
    /// A version 5 broadcast object.
    V5(BroadcastV5),
}

impl Broadcast {
    fn encrypted(&self) -> &[u8] {
        match self {
            Self::V4(v4) => v4.encrypted(),
            Self::V5(v5) => v5.encrypted(),
        }
    }

    fn signed_header(&self, header: &Header) -> Result<Vec<u8>, io::Error> {
        let mut bytes = Vec::new();
        header.write_to(&mut bytes)?;
        match self {
            Self::V4(_) => (),
            Self::V5(v5) => v5.tag.write_to(&mut bytes)?,
        }
        Ok(bytes)
    }

    /// Decrypts this broadcast object and returns the decrypted content.
    pub fn decrypt(
        &self,
        header: &Header,
        address: &Address,
    ) -> Result<content::Broadcast, DecryptError> {
        let mut bytes = Cursor::new(self.encrypted());
        let encrypted = crypto::Encrypted::sized_read_from(&mut bytes, self.encrypted().len())?;
        let private_key = address.broadcast_key();
        let decrypted = encrypted.decrypt(&private_key)?;
        let mut bytes = Cursor::new(decrypted);
        let content = content::Broadcast::read_from(&mut bytes)?;

        if content.stream_number() != header.stream_number() {
            return Err(DecryptError::StreamsNotMatch {
                headers: header.stream_number(),
                contents: content.stream_number(),
            });
        }
        // TODO check validity

        let a = content.address()?;
        match self {
            Self::V4(_) => {
                if a.version().as_u64() < 2 || a.version().as_u64() > 3 {
                    return Err(DecryptError::InvalidAddress {
                        expected: address.clone(),
                        actual: a,
                    });
                }
                if a.hash() != address.hash() {
                    return Err(DecryptError::InvalidAddress {
                        expected: address.clone(),
                        actual: a,
                    });
                }
            }
            Self::V5(_) => {
                if a.version().as_u64() < 4 {
                    return Err(DecryptError::InvalidAddress {
                        expected: address.clone(),
                        actual: a,
                    });
                }
                if a.broadcast_key() != address.broadcast_key() {
                    return Err(DecryptError::InvalidAddress {
                        expected: address.clone(),
                        actual: a,
                    });
                }
            }
        }

        content.verify(self.signed_header(header)?)?;

        Ok(content)
    }
}

/// This error indicates
/// that the conversion from object to broadcast failed.
#[derive(Debug)]
pub enum TryIntoBroadcastError {
    /// Indicates that the type of the supplied object was not broadcast.
    /// The actual type of the object is returned as a payload of this variant.
    InvalidType(ObjectType),
    /// A standard I/O error was caught during decrypting a message.
    /// The actual error caught is returned as a payload of this variant.
    IoError(io::Error),
    /// Indicates that the version of the supplied object was not supported.
    /// The actual version of the object is returned as a payload of this variant.
    UnsupportedVersion(ObjectVersion),
}

impl fmt::Display for TryIntoBroadcastError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::InvalidType(object_type) => write!(f, "invalid object type: {}", object_type),
            Self::IoError(err) => err.fmt(f),
            Self::UnsupportedVersion(version) => {
                write!(f, "unsupported broadcast version: {}", version)
            }
        }
    }
}

impl std::error::Error for TryIntoBroadcastError {}

impl From<io::Error> for TryIntoBroadcastError {
    fn from(err: io::Error) -> Self {
        Self::IoError(err)
    }
}

impl TryFrom<message::Object> for Broadcast {
    type Error = TryIntoBroadcastError;

    fn try_from(
        object: message::Object,
    ) -> Result<Self, <Self as TryFrom<message::Object>>::Error> {
        let kind = ObjectKind::try_from(object.header().object_type());
        if let Err(TryFromObjectTypeError(object_type)) = kind {
            return Err(TryIntoBroadcastError::InvalidType(object_type));
        }
        if kind.unwrap() != ObjectKind::Broadcast {
            return Err(TryIntoBroadcastError::InvalidType(
                object.header().object_type(),
            ));
        }
        match object.header().version().as_u64() {
            4 => {
                let mut bytes = Cursor::new(object.object_payload());
                let broadcast =
                    BroadcastV4::sized_read_from(&mut bytes, object.object_payload().len())?;
                Ok(Self::V4(broadcast))
            }
            5 => {
                let mut bytes = Cursor::new(object.object_payload());
                let broadcast =
                    BroadcastV5::sized_read_from(&mut bytes, object.object_payload().len())?;
                Ok(Self::V5(broadcast))
            }
            _ => Err(TryIntoBroadcastError::UnsupportedVersion(
                object.header().version(),
            )),
        }
    }
}

/// An extended network address object
/// that can represent IPv4, IPv6, Onion v2 or Onion v3 address.
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
pub struct Onionpeer {
    port: VarInt,
    addr: Vec<u8>,
}

/// The error type returned when a conversion from a onionpeer object to an extended socket address fails.
///
/// This error is used as the error type for the `TryFrom` implementation
/// for `SocketAddrExt`.
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum TryFromOnionpeerError {
    /// Indicates that the port number is out of the range.
    /// The actual number is returned as a payload of this variant.
    InvalidPort(u64),
    /// Indicates that the length of the address is invalid.
    /// The actual length is returned as a payload of this variant.
    InvalidLength(usize),
    /// Indicates that the prefix bytes of the Onion address is invalid.
    /// The actual prefix is returned as a payload of this variant.
    InvalidPrefix([u8; 6]),
    /// An error was caught during parsing an Onion V3 address.
    /// The actual error caught is returned as a payload of this variant.
    ParseOnionV3AddrError(ParseOnionV3AddrError),
}

impl fmt::Display for TryFromOnionpeerError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::InvalidPort(port) => write!(f, "invalid port: {}", port),
            Self::InvalidLength(len) => write!(f, "invalid length: {}", len),
            Self::InvalidPrefix(prefix) => {
                write!(f, "invalid prefix: {}", prefix.as_ref().to_hex_string())
            }
            Self::ParseOnionV3AddrError(err) => err.fmt(f),
        }
    }
}

impl std::error::Error for TryFromOnionpeerError {}

impl From<ParseOnionV3AddrError> for TryFromOnionpeerError {
    fn from(err: ParseOnionV3AddrError) -> Self {
        Self::ParseOnionV3AddrError(err)
    }
}

const ONION_PREFIX: [u8; 6] = [0xfd, 0x87, 0xd8, 0x7e, 0xeb, 0x43];

impl TryFrom<Onionpeer> for SocketAddrExt {
    type Error = TryFromOnionpeerError;

    fn try_from(op: Onionpeer) -> Result<Self, <Self as TryFrom<Onionpeer>>::Error> {
        if op.port.as_u64() > u16::MAX as u64 {
            return Err(TryFromOnionpeerError::InvalidPort(op.port.as_u64()));
        }
        let port = op.port.as_u64() as u16;
        let len = op.addr.len();
        if len == 16 {
            let bytes: [u8; 16] = op.addr[..].try_into().unwrap();
            let addr: Addr = bytes.into();
            let addr: AddrExt = addr.into();
            Ok(Self::new(addr, port))
        } else if len == 6 + 35 {
            if op.addr[0..6] != *ONION_PREFIX.as_ref() {
                let prefix = op.addr[0..6].try_into().unwrap();
                return Err(TryFromOnionpeerError::InvalidPrefix(prefix));
            }
            let mut bytes = [0; 35];
            bytes.copy_from_slice(&op.addr[6..]);
            let addr = OnionV3Addr::new(bytes)?;
            let addr = AddrExt::OnionV3(addr);
            Ok(Self::new(addr, port))
        } else {
            Err(TryFromOnionpeerError::InvalidLength(len))
        }
    }
}

const IPV4_PREFIX: [u8; 12] = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff];

impl From<SocketAddrExt> for Onionpeer {
    fn from(addr: SocketAddrExt) -> Self {
        match addr {
            SocketAddrExt::Ipv4(sa) => {
                let port: VarInt = (sa.port() as u64).into();
                let mut addr = IPV4_PREFIX.clone().to_vec();
                addr.extend_from_slice(&sa.ip().octets());
                Self { port, addr }
            }
            SocketAddrExt::Ipv6(sa) => {
                let port: VarInt = (sa.port() as u64).into();
                let addr = sa.ip().octets().to_vec();
                Self { port, addr }
            }
            SocketAddrExt::OnionV2(sa) => {
                let port: VarInt = (sa.port() as u64).into();
                let mut addr = ONION_PREFIX.clone().to_vec();
                addr.extend_from_slice(sa.onion_addr().as_ref());
                Self { port, addr }
            }
            SocketAddrExt::OnionV3(sa) => {
                let port: VarInt = (sa.port() as u64).into();
                let mut addr = ONION_PREFIX.clone().to_vec();
                addr.extend_from_slice(sa.onion_addr().as_ref());
                Self { port, addr }
            }
        }
    }
}

impl WriteTo for Onionpeer {
    fn write_to(&self, w: &mut dyn Write) -> io::Result<()> {
        self.port.write_to(w)?;
        self.addr.write_to(w)?;
        Ok(())
    }
}

impl SizedReadFrom for Onionpeer {
    fn sized_read_from(r: &mut dyn Read, len: usize) -> io::Result<Self>
    where
        Self: Sized,
    {
        let port = VarInt::read_from(r)?;
        let addr = Vec::<u8>::sized_read_from(r, len - port.len_bm())?;
        Ok(Self { port, addr })
    }
}