//! Crypto currency and exchange tickers and other market-related primatives
//!
use std::fmt::{self, Display};
use std::str::FromStr;
use std::cmp::{PartialEq, Eq};
use std::convert::TryFrom;

use serde::{Serialize, Deserialize};
use serde::de::{self, Deserializer, Visitor};
use serde::Serializer;
//use decimal::d128;
//use chrono::{DateTime, Utc, TimeZone};


#[macro_export]
macro_rules! c {
    ($x:tt) => {
        $crate::crypto::Currency::$x 
    }
}

#[macro_export]
macro_rules! e {
    ($x:tt) => {
        $crate::crypto::Exchange::$x 
    }
}

#[macro_export]
macro_rules! t {
    ($base:tt-$quote:tt) => {
        $crate::crypto::Ticker { 
            base: c!($base),
            quote: c!($quote)
        }
    }
}

/// which side of the transaction (buying or selling)
/// a price/trade is
///
#[repr(u8)]
#[derive(Debug, PartialEq, Clone, Copy, Eq, Serialize)]
pub enum Side { 
    Bid = 1,
    Ask = 2,
}

impl TryFrom<u8> for Side {
    type Error = Error;
    fn try_from(n: u8) -> Result<Self, Self::Error> {
        match n {
            1 => Ok(Side::Bid),
            2 => Ok(Side::Ask),
            other => Err(Error::IllegalFormat(Box::new(format!("Expected 1 or 2 (received {})", other))))
        }
    }
}

impl From<Side> for u8 {
    fn from(side: Side) -> Self {
        match side {
            Side::Bid => 1,
            Side::Ask => 2
        }
    }
}

impl Side {
    pub fn as_verb(&self) -> &'static str {
        match *self {
            Side::Bid => "buy",
            Side::Ask => "sell"
        }
    }

    pub fn as_past_tense(&self) -> &'static str {
        match *self {
            Side::Bid => "bought",
            Side::Ask => "sold"
        }
    }

    pub fn as_past_tense_title_case(&self) -> &'static str {
        match *self {
            Side::Bid => "Bought",
            Side::Ask => "Sold"
        }
    }

    pub fn to_str(&self) -> &'static str {
        match *self {
            Side::Bid => "bid",
            Side::Ask => "ask"
        }
    }


    pub fn is_bid(&self) -> bool {
        match self {
            &Side::Bid => true,
            _ => false
        }
    }

    pub fn is_ask(&self) -> bool { !self.is_bid() }
}

impl <'de> Deserialize<'de> for Side {
    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
        where D: Deserializer<'de> {

        let side = String::deserialize(deserializer)?;
        match side.to_lowercase().as_ref() {
            "bid" | "buy" | "bids" => Ok(Side::Bid),
            "ask" | "sell" | "asks"  => Ok(Side::Ask),
            other => Err(de::Error::custom(format!("could not parse Side from '{}'", other))),
        }
    }
}

impl Display for Side {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{:?}", self)
    }
}

impl FromStr for Side {
    type Err = Error;

    fn from_str(s: &str) -> Result<Self, Error> {
        match s.to_lowercase().as_ref() {
            "bid" | "buy" | "bids" => Ok(Side::Bid),
            "ask" | "sell" | "asks"  => Ok(Side::Ask),
            s => Err(Error::IllegalFormat(Box::new(s.to_string())))
        }
    }
}


macro_rules! make_currency {
    //(@as_ident $name:ident) => { $name };

    ($(|$ticker:ident, $name:expr, $code:expr, $upper:ident),*) => {
        #[derive(Debug, PartialEq, Clone, Hash, Eq, Copy, PartialOrd, Ord, Serialize)]
        #[allow(non_camel_case_types)]
        #[repr(u8)]
        pub enum Currency {
            $($ticker = $code),*
        }

        impl Currency {
            pub fn name(&self) -> &'static str {
                match *self {
                    $(
                        c!($ticker) => { $name }
                    ),*
                }
            }

            pub fn as_str(&self) -> &'static str {
                match *self {
                    $(
                        c!($ticker) => { stringify!($ticker) }
                    ),*
                }
            }

            pub fn to_str_uppercase(&self) -> &'static str {
                match *self {
                    $(
                        c!($ticker) => { stringify!($upper) }
                    ),*
                }
            }

            #[allow(non_upper_case_globals)]
            pub fn from_bytes<'a>(bytes: &'a [u8]) -> Result<Self, UnlistedCurrency<'a>> {
                // this declares for each currency the equivalent of
                // const BTC : &[u8] = "btc".as_bytes();
                $(
                    const $upper: &[u8] = stringify!($ticker).as_bytes();
                )*
                
                // this declares for each currency the equivalent of
                // const btc : &[u8] = "BTC".as_bytes();
                $(
                    const $ticker: &[u8] = stringify!($upper).as_bytes();
                )*

                match bytes {
                    // first try lowercase (identified by uppercase consts)
                    $(
                        $upper => { return Ok(Currency::$ticker) }
                    )*

                    // then try uppercase (identified by lowercase consts)
                    $(
                        $ticker => { return Ok(Currency::$ticker) }
                    )*

                    other => Err(UnlistedCurrency(std::str::from_utf8(other).unwrap_or("<utf8 error>")))
                }
            }

            /// Optimized for expecting lowercase. Does not attempt to search beyond
            /// every currency symbol in lowercase.
            ///
            pub fn from_str_lowercase<'a>(s: &'a str) -> Result<Self, UnlistedCurrency<'a>> {
                match s {
                    $(
                        stringify!($ticker) => { Ok(c!($ticker)) }

                    )*

                    other => Err(UnlistedCurrency(other))
                }
            }

            /// Optimized for expecting uppercase. Does not attempt to search beyond
            /// every currency symbol in uppercase.
            ///
            pub fn from_str_uppercase<'a>(s: &'a str) -> Result<Self, UnlistedCurrency<'a>> {
                match s {
                    $(
                        stringify!($upper) => { Ok(c!($ticker)) }

                    )*

                    other => Err(UnlistedCurrency(other))
                }
            }

            pub fn all() -> Vec<Self> {
                vec![
                    $( c!($ticker) ),*
                ]
            }

            pub fn variant_str_slice() -> &'static [&'static str] {
                &[
                    $(
                        stringify!($ticker)
                    ),*
                ]
            }
        }

        impl TryFrom<u8> for Currency {
            type Error = Error;
            fn try_from(n: u8) -> Result<Self, Self::Error> {
                match n {
                    $(
                        $code => { Ok(c!($ticker)) }
                    ),*

                    other => Err(Error::IllegalFormat(Box::new(format!("Illegal Currency value: {}", other))))
                }
            }
        }

        impl From<Currency> for u8 {
            fn from(c: Currency) -> Self {
                match c {
                    $(
                        c!($ticker) => { $code }
                    ),*
                }
            }
        }

        impl FromStr for Currency {
            type Err = Error;

            fn from_str(s: &str) -> Result<Self, Self::Err> {
                let t = match s.to_lowercase().trim() {
                    $(
                        stringify!($ticker) => { c!($ticker) }
                    ),*

                    "xbt" => c!(btc),

                    _ => {
                        return Err(Error::IllegalCurrency);
                    }
                };
                Ok(t)
            }
        }

        #[test]
        fn it_verifies_currency_lower_and_upper_consistency() {
            let currencies = vec![ $(c!($ticker)),* ];
            for c in &currencies {
                assert_eq!(c.as_str().to_uppercase(), c.to_str_uppercase().to_string());
            }
        }

        #[test]
        fn checks_from_bytes_for_lower_and_upper_tickers() {
            $(
                assert_eq!(
                    Currency::from_bytes(Currency::$ticker.as_str().as_bytes()).unwrap(),
                    Currency::$ticker
                );
                assert_eq!(
                    Currency::from_bytes(Currency::$ticker.to_str_uppercase().as_bytes()).unwrap(), 
                    Currency::$ticker
                );
            )*
        }

        #[test]
        fn check_serde_json_deser() {
            #[derive(Serialize, Deserialize, PartialEq, Debug)]
            struct A {
                pub denom: Currency,
            }

            $(
                {
                    let a = A { denom: Currency::$ticker };
                    let to_json = serde_json::to_string(&a).unwrap();
                    let manual_json = format!("{{\"denom\":\"{}\"}}", stringify!($ticker));
                    let manual_json_uppercase = format!("{{\"denom\":\"{}\"}}", stringify!($upper));

                    assert_eq!(a, serde_json::from_str(&to_json).unwrap());
                    assert_eq!(a, serde_json::from_str(&manual_json).unwrap());
                    assert_eq!(a, serde_json::from_str(&manual_json_uppercase).unwrap());
                    assert_eq!(a, serde_json::from_slice(manual_json.as_bytes()).unwrap());
                    assert_eq!(a, serde_json::from_slice(manual_json_uppercase.as_bytes()).unwrap());

                }
            )*
        }
    }
}

make_currency!(
    | btc,      "Bitcoin",                1,        BTC,
    | eth,      "Ethereum",               2,        ETH,
    | xmr,      "Monero",                 3,        XMR,
    | usdt,     "Tether",                 4,        USDT,
    | ltc,      "Litecoin",               5,        LTC,
    | dash,     "Dash",                   6,        DASH,
    | nvc,      "Novacoin",               7,        NVC,
    | ppc,      "Peercoin",               8,        PPC,
    | zec,      "Zcash",                  9,        ZEC,
    | xrp,      "Ripple",                 10,       XRP,
    | gnt,      "Golem",                  11,       GNT,
    | steem,    "Steem",                  12,       STEEM,
    | rep,      "Augur",                  13,       REP,
    | gno,      "Gnosis",                 14,       GNO,
    | etc,      "Ethereum Classic",       15,       ETC,
    | icn,      "Iconomi",                16,       ICN,
    | xlm,      "Stellar",                17,       XLM,
    | mln,      "Melon",                  18,       MLN,
    | bcn,      "Bytecoin",               19,       BCN,
    | bch,      "Bitcoin Cash",           20,       BCH,
    | doge,     "Dogecoin",               21,       DOGE,
    | eos,      "Eos",                    22,       EOS,
    | nxt,      "Nxt",                    23,       NXT,
    | sc,       "Siacoin",                24,       SC,
    | zrx,      "0x",                     25,       ZRX,
    | bat,      "Basic Attention Token",  26,       BAT,
    | ada,      "Cardano",                27,       ADA,
    | usdc,     "USD Coin",               28,       USDC,
    | dai,      "Dai",                    29,       DAI,
    | mkr,      "Maker",                  30,       MKR,
    | loom,     "Loom Network",           31,       LOOM,
    | cvc,      "Civic",                  32,       CVC,
    | mana,     "Decentraland",           33,       MANA,
    | dnt,      "district0x",             34,       DNT,
    | zil,      "Zilliqa",                35,       ZIL,
    | link,     "Chainlink",              36,       LINK,
    | algo,     "Algorand",               37,       ALGO,
    | xtz,      "Tezos",                  38,       XTZ,
    | oxt,      "Orchid",                 39,       OXT,
    | atom,     "Cosmos",                 40,       ATOM,

    // fiat: u8 code starts at 100 (can be used to filter/sort)
    | usd,      "U.S. Dollar",            100,      USD,
    | eur,      "Euro",                   101,      EUR,
    | rur,      "Ruble",                  102,      RUR,
    | jpy,      "Yen",                    103,      JPY,
    | gbp,      "Pound",                  104,      GBP,
    | chf,      "Franc",                  105,      CHF,
    | cad,      "Canadian Dollar",        106,      CAD,
    | aud,      "Australian Dollar",      107,      AUD,
    | zar,      "Rand",                   108,      ZAR,
    | mxn,      "Peso",                   109,      MXN
);

impl Currency {
    /// Convert fiat peg to tether equivalent.
    ///
    /// # Examples
    ///
    /// ```
    /// #[macro_use]
    /// extern crate markets;
    /// fn main() {
    ///     assert_eq!(c!(usd).to_tether(), c!(usdt));
    ///     assert_eq!(c!(btc).to_tether(), c!(btc));
    /// }
    /// ```
    ///
    pub fn to_tether(&self) -> Self {
        match *self {
            c!(usd) => c!(usdt),
            other => other
        }
    }

    /// Converts stablecoins into fiat peg.
    ///
    /// # Examples
    ///
    /// ```
    /// #[macro_use]
    /// extern crate markets;
    /// fn main() {
    ///     assert_eq!(c!(usdt).from_tether(), c!(usd));
    ///     assert_eq!(c!(btc).from_tether(), c!(btc));
    /// }
    /// ```
    ///
    pub fn from_tether(&self) -> Self {
        match *self {
            c!(usdt) => c!(usd),
            other => other
        }
    }
}

/// # Panics
///
/// The `TryFrom` implementation in this macro will panic it is passed
/// a value greater than the maximum value a `u8` can store.
///
macro_rules! use_u8_impl_for_int {
    ($t:ty, $int:ty) => {
        impl From<$t> for $int {
            fn from(t: $t) -> Self {
                u8::from(t) as $int
            }
        }

        impl TryFrom<$int> for $t {
            type Error = Error;

            fn try_from(n: $int) -> Result<Self, Self::Error> {
                TryFrom::try_from(n as u8)
            }
        }
    }
}

use_u8_impl_for_int!(Currency, i16);
use_u8_impl_for_int!(Exchange, i16);
use_u8_impl_for_int!(Ticker, i16);
use_u8_impl_for_int!(Side, i16);

#[test]
fn check_generated_currency_fns() {
    assert_eq!(c!(usd), Currency::usd);
    assert_eq!(c!(usd).name(), "U.S. Dollar");
    assert_eq!(Currency::try_from(1_u8).unwrap(), c!(btc));
    assert_eq!(u8::from(c!(usd)), 100_u8);
    assert_eq!(i16::from(c!(usd)), 100_i16);
}

struct CurrencyVisitor;
struct ExchangeVisitor;
struct TickerVisitor;

impl<'de> Visitor<'de> for CurrencyVisitor {
    type Value = Currency;

    fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
        formatter.write_str("a currency symbol or ticker, like those used by exchanges (e.g. btc, usd)")
    }

    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E> where
        E: de::Error
    {
        Currency::from_str_lowercase(v)
            .or_else(|_| Currency::from_str_uppercase(v))
            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))
    }

    fn visit_borrowed_str<E>(self, v: &'de str) -> Result<Self::Value, E> where
        E: de::Error
    {
        Currency::from_str_lowercase(v)
            .or_else(|_| Currency::from_str_uppercase(v))
            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))
    }

    fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E> where
        E: de::Error
    {
        Currency::from_bytes(v)
            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))
    }

    fn visit_borrowed_bytes<E>(self, v: &'de [u8]) -> Result<Self::Value, E> where
        E: de::Error
    {
        Currency::from_bytes(v)
            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))
    }
}

impl<'de> Visitor<'de> for ExchangeVisitor {
    type Value = Exchange;

    fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
        formatter.write_str("a four-character exchange symbol (e.g. gdax, bmex)")
    }

    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E> where
        E: de::Error
    {
        Exchange::from_str_lowercase(v)
            .or_else(|_| Exchange::from_str_uppercase(v))
            .map_err(|UnlistedExchange(unknown)| E::unknown_variant(unknown, Exchange::variant_str_slice()))
    }

    fn visit_borrowed_str<E>(self, v: &'de str) -> Result<Self::Value, E> where
        E: de::Error
    {
        Exchange::from_str_lowercase(v)
            .or_else(|_| Exchange::from_str_uppercase(v))
            .map_err(|UnlistedExchange(unknown)| E::unknown_variant(unknown, Exchange::variant_str_slice()))
    }

    fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E> where
        E: de::Error
    {
        Exchange::from_bytes(v)
            .map_err(|UnlistedExchange(unknown)| E::unknown_variant(unknown, Exchange::variant_str_slice()))
    }

    fn visit_borrowed_bytes<E>(self, v: &'de [u8]) -> Result<Self::Value, E> where
        E: de::Error
    {
        Exchange::from_bytes(v)
            .map_err(|UnlistedExchange(unknown)| E::unknown_variant(unknown, Exchange::variant_str_slice()))
    }
}

impl<'de> Visitor<'de> for TickerVisitor {
    type Value = Ticker;

    fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
        formatter.write_str("a currency rate symbol or ticker, like those used by exchanges (e.g. btc_usd)")
    }

    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E> where
        E: de::Error
    {
        let mut parts = v.split(|c| c == '_' || c == '-' || c == '/');

        match parts.next() {
            Some(base_str) => {
                match parts.next() {
                    Some(quote_str) => {
                        let base = Currency::from_str_lowercase(base_str)
                            .or_else(|_| Currency::from_str_uppercase(base_str))
                            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))?;

                        let quote = Currency::from_str_lowercase(quote_str)
                            .or_else(|_| Currency::from_str_uppercase(quote_str))
                            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))?;

                        Ok(Ticker { base, quote })
                    }

                    None => Err(E::missing_field("quote"))
                }
            }

            None => Err(E::missing_field("base"))
        }
    }
                
    fn visit_borrowed_str<E>(self, v: &'de str) -> Result<Self::Value, E> where
        E: de::Error
    {
        let mut parts = v.split(|c| c == '_' || c == '-' || c == '/');

        match parts.next() {
            Some(base_str) => {
                match parts.next() {
                    Some(quote_str) => {
                        let base = Currency::from_str_lowercase(base_str)
                            .or_else(|_| Currency::from_str_uppercase(base_str))
                            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))?;

                        let quote = Currency::from_str_lowercase(quote_str)
                            .or_else(|_| Currency::from_str_uppercase(quote_str))
                            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))?;

                        Ok(Ticker { base, quote })
                    }

                    None => Err(E::missing_field("quote"))
                }
            }

            None => Err(E::missing_field("base"))
        }
    }

    fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E> where
        E: de::Error
    {
        let mut parts = v.split(|&c| c == b'_' || c == b'-' || c == b'/');

        match parts.next() {
            Some(base_str) => {
                match parts.next() {
                    Some(quote_str) => {
                        let base = Currency::from_bytes(base_str)
                            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))?;

                        let quote = Currency::from_bytes(quote_str)
                            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))?;

                        Ok(Ticker { base, quote })
                    }

                    None => Err(E::missing_field("quote"))
                }
            }

            None => Err(E::missing_field("base"))
        }
    }

    fn visit_borrowed_bytes<E>(self, v: &'de [u8]) -> Result<Self::Value, E> where
        E: de::Error
    {
        let mut parts = v.split(|&c| c == b'_' || c == b'-' || c == b'/');

        match parts.next() {
            Some(base_str) => {
                match parts.next() {
                    Some(quote_str) => {
                        let base = Currency::from_bytes(base_str)
                            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))?;

                        let quote = Currency::from_bytes(quote_str)
                            .map_err(|UnlistedCurrency(unknown)| E::unknown_variant(unknown, Currency::variant_str_slice()))?;

                        Ok(Ticker { base, quote })
                    }

                    None => Err(E::missing_field("quote"))
                }
            }

            None => Err(E::missing_field("base"))
        }
    }
}

impl <'de> Deserialize<'de> for Currency {
    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
        where D: Deserializer<'de>
    {
        deserializer.deserialize_bytes(CurrencyVisitor)
    }
}

impl <'de> Deserialize<'de> for Exchange {
    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
        where D: Deserializer<'de>
    {
        deserializer.deserialize_bytes(ExchangeVisitor)
    }
}

impl <'de> Deserialize<'de> for Ticker {
    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
        where D: Deserializer<'de>
    {
        deserializer.deserialize_bytes(TickerVisitor)
    }
}

impl Display for Currency {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "{:?}", self)
    }
}

macro_rules! make_exchange {
    ($(|$ticker:ident, $name:expr, $code:expr, $upper:ident),*) => {
        #[derive(Debug, PartialEq, Clone, Hash, Eq, Copy, PartialOrd, Ord,
                 Serialize)]
        #[allow(non_camel_case_types)]
        #[repr(u8)]
        pub enum Exchange {
            $(
                #[doc = $name]
                $ticker = $code
            ),*
        }

        impl Exchange {
            pub fn name(&self) -> &'static str {
                match *self {
                    $(
                        e!($ticker) => { $name }
                    ),*
                }
            }

            pub fn as_str(&self) -> &'static str {
                match *self {
                    $(
                        e!($ticker) => { stringify!($ticker) }
                    ),*
                }
            }

            pub fn to_str_uppercase(&self) -> &'static str {
                match *self {
                    $(
                        e!($ticker) => { stringify!($upper) }
                    ),*
                }
            }

            pub fn all() -> Vec<Self> {
                vec![
                    $( e!($ticker) ),*
                ]
            }

            pub fn variant_str_slice() -> &'static [&'static str] {
                &[
                    $(
                        stringify!($ticker)
                    ),*
                ]
            }

            #[allow(non_upper_case_globals)]
            pub fn from_bytes<'a>(bytes: &'a [u8]) -> Result<Self, UnlistedExchange<'a>> {
                // this declares for each currency the equivalent of
                // const BTC : &[u8] = "btc".as_bytes();
                $(
                    const $upper: &[u8] = stringify!($ticker).as_bytes();
                )*
                
                // this declares for each currency the equivalent of
                // const btc : &[u8] = "BTC".as_bytes();
                $(
                    const $ticker: &[u8] = stringify!($upper).as_bytes();
                )*

                match bytes {
                    // first try lowercase (identified by uppercase consts)
                    $(
                        $upper => { return Ok(Exchange::$ticker) }
                    )*

                    // then try uppercase (identified by lowercase consts)
                    $(
                        $ticker => { return Ok(Exchange::$ticker) }
                    )*

                    other => Err(UnlistedExchange(std::str::from_utf8(other).unwrap_or("<utf8 error>")))
                }
            }

            /// Optimized for expecting lowercase. Does not attempt to search beyond
            /// every currency symbol in lowercase.
            ///
            pub fn from_str_lowercase<'a>(s: &'a str) -> Result<Self, UnlistedExchange<'a>> {
                match s {
                    $(
                        stringify!($ticker) => { Ok(Exchange::$ticker) }

                    )*

                    other => Err(UnlistedExchange(other))
                }
            }

            /// Optimized for expecting uppercase. Does not attempt to search beyond
            /// every currency symbol in uppercase.
            ///
            pub fn from_str_uppercase<'a>(s: &'a str) -> Result<Self, UnlistedExchange<'a>> {
                match s {
                    $(
                        stringify!($upper) => { Ok(Exchange::$ticker) }

                    )*

                    other => Err(UnlistedExchange(other))
                }
            }
        }

        impl TryFrom<u8> for Exchange {
            type Error = Error;
            fn try_from(n: u8) -> Result<Self, Self::Error> {
                match n {
                    $(
                        $code => { Ok(e!($ticker)) }
                    ),*

                    _ => Err(Error::IllegalExchangeCode(n))
                }
            }
        }

        impl From<Exchange> for u8 {
            fn from(c: Exchange) -> Self {
                match c {
                    $(
                        e!($ticker) => { $code }
                    ),*
                }
            }
        }

        impl FromStr for Exchange {
            type Err = Error;

            fn from_str(s: &str) -> Result<Self, Self::Err> {
                let t = match s.to_lowercase().trim() {
                    $(
                        stringify!($ticker) => { e!($ticker) }
                    ),*

                    _ => {
                        return Err(Error::IllegalExchange);
                    }
                };
                Ok(t)
            }
        }

        /// Holds an object of the same type for each exchange.
        ///
        pub struct ByExchange<T> {
            $(
                pub $ticker: T
            ),*
        }

        impl<T> ByExchange<T> {
            pub fn new(
                $(
                    $ticker: T
                ),*
            ) -> Self {
                Self {
                    $(
                        $ticker
                    ),*
                }
            }

            pub fn of(&self, exchange: &Exchange) -> &T {
                match exchange {
                    $(
                        &e!($ticker) => &self.$ticker
                    ),*
                }
            }

            pub fn of_mut(&mut self, exchange: &Exchange) -> &mut T {
                match exchange {
                    $(
                        &e!($ticker) => &mut self.$ticker
                    ),*
                }
            }

            // to match map apis:

            pub fn get(&self, exchange: &Exchange) -> Option<&T> {
                Some(self.of(exchange))
            }

            pub fn get_mut(&mut self, exchange: &Exchange) -> Option<&mut T> {
                Some(self.of_mut(exchange))
            }
        }

        impl<T> Default for ByExchange<T>
            where T: Default
        {
            fn default() -> Self {
                ByExchange {
                    $(
                        $ticker: Default::default()
                    ),*
                }
            }
        }

        impl<T> Clone for ByExchange<T>
            where T: Clone
        {
            fn clone(&self) -> Self {
                ByExchange {
                    $(
                        $ticker: self.$ticker.clone()
                    ),*
                }
            }
        }

        #[test]
        fn it_verifies_exch_lower_and_upper_consistency() {
            for x in Exchange::all() {
                assert_eq!(x.as_str().to_uppercase(), x.to_str_uppercase().to_string());
            }
        }

        #[test]
        fn checks_from_bytes_for_lower_and_upper_tickers_exch() {
            $(
                assert_eq!(
                    Exchange::from_bytes(Exchange::$ticker.as_str().as_bytes()).unwrap(),
                    Exchange::$ticker
                );
                assert_eq!(
                    Exchange::from_bytes(Exchange::$ticker.to_str_uppercase().as_bytes()).unwrap(), 
                    Exchange::$ticker
                );
            )*
        }

        #[test]
        fn check_serde_json_deser_exch() {
            #[derive(Serialize, Deserialize, PartialEq, Debug)]
            struct A {
                pub exch: Exchange,
            }

            $(
                {
                    let a = A { exch: Exchange::$ticker };
                    let to_json = serde_json::to_string(&a).unwrap();
                    let manual_json = format!("{{\"exch\":\"{}\"}}", stringify!($ticker));
                    let manual_json_uppercase = format!("{{\"exch\":\"{}\"}}", stringify!($upper));

                    assert_eq!(a, serde_json::from_str(&to_json).unwrap());
                    assert_eq!(a, serde_json::from_str(&manual_json).unwrap());
                    assert_eq!(a, serde_json::from_str(&manual_json_uppercase).unwrap());
                    assert_eq!(a, serde_json::from_slice(manual_json.as_bytes()).unwrap());
                    assert_eq!(a, serde_json::from_slice(manual_json_uppercase.as_bytes()).unwrap());

                }
            )*
        }
    }
}

make_exchange!(
    | plnx, "Poloniex", 1,  PLNX,
    | krkn, "Kraken",   2,  KRKN,
    | gdax, "GDAX",     3,  GDAX,
    | exmo, "Exmo",     4,  EXMO,
    | bits, "Bitstamp", 5,  BITS,
    | bmex, "Bitmex",   6,  BMEX,
    | btfx, "Bitfinex", 7,  BTFX,
    | bnce, "Binance",  8,  BNCE,
    | okex, "OKEx",     9,  OKEX,
    | drbt, "Deribit",  10, DRBT
);

#[test]
fn check_generated_exchange_fns() {
    assert_eq!(e!(plnx), Exchange::plnx);
    assert_eq!(e!(plnx).name(), "Poloniex");
    assert_eq!(Exchange::try_from(2_u8).unwrap(), e!(krkn));
    assert_eq!(u8::from(e!(gdax)), 3_u8);
}

impl Display for Exchange {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "{}", self.as_str())
    }
}

#[derive(Debug, Clone, Hash, PartialEq, Eq, Copy, PartialOrd, Ord)]
pub struct Ticker {
    pub base: Currency,
    pub quote: Currency,
}

impl Ticker {
    pub fn flip(&self) -> Self {
        Ticker { base: self.quote, quote: self.base }
    }

    pub fn to_s(&self) -> String {
        format!("{}", self)
    }
}

macro_rules! ticker_to_u8 {
    ($(|$base:tt-$quote:tt, $u_base:tt-$u_quote:tt, $n:expr),*) => {
        impl From<Ticker> for u8 {
            fn from(t: Ticker) -> Self {
                match t {
                    $(
                        t!($base-$quote) => { $n }
                    ),*

                    _ =>  0
                }
            }
        }

        impl TryFrom<u8> for Ticker {
            type Error = Error;
            fn try_from(n: u8) -> Result<Self, Self::Error> {
                match n {
                    $(
                        $n => { Ok(t!($base-$quote)) }
                    ),*

                    other =>  Err(Error::IllegalValue(other))
                }
            }
        }

        impl Ticker {
            pub fn as_str(&self) -> &'static str {
                match *self {
                    $(
                        t!($base-$quote) => { concat!(stringify!($base), "_", stringify!($quote)) }
                    ),*

                    _ => "xxx_xxx"
                }
            }

            pub fn as_str_dash(&self) -> &'static str {
                match *self {
                    $( t!($base-$quote) => { concat!(stringify!($base), "-", stringify!($quote)) } ),*
                    _ => "xxx-xxx"
                }
            }

            pub fn to_str_uppercase(&self) -> &'static str {
                match *self {
                    $(
                        t!($base-$quote) => { concat!(stringify!($u_base), "_", stringify!($u_quote)) }
                    ),*

                    _ => "XXX_XXX"
                }
            }

            pub fn to_str_reversed(&self) -> &'static str {
                match *self {
                    $(
                        t!($base-$quote) => { concat!(stringify!($quote), "_", stringify!($base)) }
                    ),*

                    _ => "xxx_xxx"
                }
            }

            pub fn to_str_uppercase_reversed(&self) -> &'static str {
                match *self {
                    $(
                        t!($base-$quote) => { concat!(stringify!($u_quote), "_", stringify!($u_base)) }
                    ),*

                    _ => "XXX_XXX"
                }
            }

            /// t!(btc-usd) -> "BTC-USD"
            ///
            pub fn to_str_uppercase_dash_sep(&self) -> &'static str {
                match *self {
                    $(
                        t!($base-$quote) => { concat!(stringify!($u_base), "-", stringify!($u_quote)) }
                    ),*

                    _ => "XXX-XXX"
                }
            }

            pub fn as_gdax_str(&self) -> &'static str { self.to_str_uppercase_dash_sep() }

            /// Note - this performs the flip and fails for tickers not in the list.
            ///
            pub fn from_str_uppercase_reverse<'a>(s: &'a str) -> Result<Ticker, UnlistedTicker<'a>> {
                match s {
                    $(
                        concat!(stringify!($u_quote), "_", stringify!($u_base)) => { Ok(t!($base-$quote)) }
                    )*

                    other => Err(UnlistedTicker(other))
                }
            }

            pub fn from_str_uppercase_dash_sep(s: &str) -> Result<Ticker, Error> {
                match s {
                    $(
                        concat!(stringify!($u_base), "-", stringify!($u_quote)) => { Ok(t!($base-$quote)) }
                    )*

                    other => ticker_parse_last_resort(other)
                }
            }

            pub fn from_str_bitfinex(s: &str) -> Result<Ticker, Error> {
                match s {
                    $(
                        concat!(stringify!($u_base), stringify!($u_quote)) => { Ok(t!($base-$quote)) }
                    )*

                    other => ticker_parse_last_resort(other)
                }
            }

            pub fn from_str_bitmex(s: &str) -> Result<Ticker, Error> {
                match s {
                    "XBTUSD" => Ok(t!(btc-usd)),
                    "ETHUSD" => Ok(t!(eth-usd)),

                    $(
                        concat!(stringify!($u_base), stringify!($u_quote)) => { Ok(t!($base-$quote)) }
                    )*

                    other => ticker_parse_last_resort(other)
                }
            }

        }

        fn ticker_parse_last_resort(other: &str) -> Result<Ticker, Error> {
            match other.find('_').or_else(|| other.find('-')).or_else(|| other.find('/')) {
                Some(sep) if sep < other.len() - 1 => {
                    let base = Currency::from_str(&other[..sep])?;
                    let quote = Currency::from_str(&other[sep + 1..])?;
                    Ok(Ticker { base, quote })
                }

                _ => Err(Error::IllegalFormat(Box::new(format!("failed to parse Ticker '{}'", other))))
            }
        }


        impl FromStr for Ticker {
            type Err = Error;

            fn from_str(s: &str) -> Result<Self, Error> {
                match s {
                    $(
                          concat!(stringify!($base), "_", stringify!($quote))
                        //| concat!(stringify!($base), "-", stringify!($quote))
                        //| concat!(stringify!($base), "/", stringify!($quote))
                        //| concat!(stringify!($u_base), "_", stringify!($u_quote))
                        //| concat!(stringify!($u_base), "-", stringify!($u_quote))
                        //| concat!(stringify!($u_base), "-", stringify!($u_quote))
                                => { Ok(t!($base-$quote)) }
                    )*

                    other => ticker_parse_last_resort(other)
                }
            }
        }

        #[test]
        fn it_verifies_ticker_lower_and_upper_consistency() {
            let tickers = vec![ $(t!($base-$quote)),*];
            for t in &tickers {
                assert_eq!(t.as_str().to_uppercase(), t.to_str_uppercase().to_string());
            }
        }

        #[test]
        fn check_serde_json_deser_ticker() {
            #[derive(Serialize, Deserialize, PartialEq, Debug)]
            struct A {
                pub ticker: Ticker,
            }

            $(
                {
                    let a = A { ticker: Ticker { base: Currency::$base, quote: Currency::$quote } };
                    let to_json = serde_json::to_string(&a).unwrap();
                    assert_eq!(a, serde_json::from_str(&to_json).unwrap());

                    for sep in ["_", "-", "/"].iter() {
                        let manual_json = format!("{{\"ticker\":\"{}{}{}\"}}", stringify!($base), sep, stringify!($quote));
                        let manual_json_uppercase = format!("{{\"ticker\":\"{}{}{}\"}}", stringify!($u_base), sep, stringify!($u_quote));

                        assert_eq!(a, serde_json::from_str(&manual_json).unwrap());
                        assert_eq!(a, serde_json::from_str(&manual_json_uppercase).unwrap());
                        assert_eq!(a, serde_json::from_slice(manual_json.as_bytes()).unwrap());
                        assert_eq!(a, serde_json::from_slice(manual_json_uppercase.as_bytes()).unwrap());
                    }
                }
            )*
        }
    }
}

ticker_to_u8!(
    |btc-usd,  BTC-USD,  1,
    |xmr-usd,  XMR-USD,  2,
    |eth-usd,  ETH-USD,  3,
    |ltc-usd,  LTC-USD,  4,
    |etc-usd,  ETC-USD,  5,
    |xrp-usd,  XRP-USD,  6,
    |bch-usd,  BCH-USD,  7,
    |zec-usd,  ZEC-USD,  8,
    |dash-usd, DASH-USD, 9,
    |rep-usd,  REP-USD,  10,

    |btc-usdt, BTC-USDT, 11,
    |xmr-usdt, XMR-USDT, 12,
    |eth-usdt, ETH-USDT, 13,
    |ltc-usdt, LTC-USDT, 14,
    |etc-usdt, ETC-USDT, 15,
    |xrp-usdt, XRP-USDT, 16,
    |bch-usdt, BCH-USDT, 17,
    |zec-usdt, ZEC-USDT, 18,
    |dash-usdt,DASH-USDT,19,
    |rep-usdt, REP-USDT, 20,

    |xmr-btc,  XMR-BTC,  21,
    |eth-btc,  ETH-BTC,  22,
    |ltc-btc,  LTC-BTC,  23,
    |etc-btc,  ETC-BTC,  24,
    |xrp-btc,  XRP-BTC,  25,
    |bch-btc,  BCH-BTC,  26,
    |zec-btc,  ZEC-BTC,  27,
    |dash-btc, DASH-BTC, 28,
    |rep-btc,  REP-BTC,  29,

    |zec-eth,  ZEC-ETH,  30,
    |etc-eth,  ETC-ETH,  31,
    |bch-eth,  BCH-ETH,  32,
    |rep-eth,  REP-ETH,  33,

    |btc-eur,  BTC-EUR,  34,
    |btc-jpy,  BTC-JPY,  35,
    |btc-gbp,  BTC-GBP,  36,
    |btc-cad,  BTC-CAD,  37,

    |eth-eur,  ETH-EUR,  38,
    |eth-jpy,  ETH-JPY,  39,
    |eth-gbp,  ETH-GBP,  40,
    |eth-cad,  ETH-CAD,  41,

    |ltc-eur,  LTC-EUR,  42,
    |ltc-jpy,  LTC-JPY,  43,
    |ltc-gbp,  LTC-GBP,  44,
    |ltc-cad,  LTC-CAD,  45,

    |xmr-eur,  XMR-EUR,  46,
    |bch-eur,  BCH-EUR,  47,
    |rep-eur,  REP-EUR,  48,
    |etc-eur,  ETC-EUR,  49,

    |usdt-usd, USDT-USD, 50

    // Note: a trailing comma will throw off the whole thing.

);

#[test]
fn check_generated_ticker_fns() {
    assert_eq!(t!(btc-usd), Ticker { base: Currency::btc, quote: Currency::usd });
    assert_eq!(t!(btc-usd).as_str(), "btc_usd");
    assert_eq!(t!(eth-jpy).as_str(), "eth_jpy");
    assert_eq!(t!(usd-btc).as_str(), "xxx_xxx");
    assert_eq!(u8::from(t!(btc-usd)), 1_u8);
    assert_eq!(u8::from(t!(btc-cad)), 37_u8);
    assert_eq!(Ticker::try_from(1_u8).unwrap(), t!(btc-usd));
    assert_eq!(Ticker::try_from(21_u8).unwrap(), t!(xmr-btc));
    assert!(Ticker::try_from(121_u8).is_err());
}

impl Into<String> for Ticker {
    fn into(self) -> String {
        format!("{}_{}", self.base, self.quote)
    }
}

impl From<(Currency, Currency)> for Ticker {
    fn from(basequote: (Currency, Currency)) -> Self {
        let (base, quote) = basequote;
        Ticker { base, quote }
    }
}

impl Serialize for Ticker {
    fn serialize<S>(&self, serializer: S) -> ::std::result::Result<S::Ok, S::Error>
        where S: Serializer
    {
        serializer.serialize_str(&format!("{}_{}", self.base, self.quote))
    }
}

impl Display for Ticker {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "{}_{}", self.base, self.quote)
    }
}

#[derive(Debug, Clone)]
pub enum Error {
    IllegalCurrency,
    IllegalExchange,
    IllegalValue(u8),
    IllegalFormat(Box<String>),
    IllegalExchangeCode(u8),
    NaN,
}

impl Display for Error {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "{:?}", self)
    }
}

impl ::std::error::Error for Error {
    fn description(&self) -> &str { "MoneyError" }
}

#[derive(Debug)]
pub struct UnlistedTicker<'a>(pub &'a str);

impl<'a> Display for UnlistedTicker<'a> {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "UnlistedTicker({})", self.0)
    }
}

#[derive(Debug)]
pub struct UnlistedCurrency<'a>(&'a str);

impl<'a> Display for UnlistedCurrency<'a> {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "UnlistedCurrency({})", self.0)
    }
}

#[derive(Debug)]
pub struct UnlistedExchange<'a>(&'a str);

impl<'a> Display for UnlistedExchange<'a> {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "UnlistedExchange({})", self.0)
    }
}

#[allow(unused)]
#[cfg(test)]
mod tests {
    use super::*;
    #[cfg(feature = "unstable")]
    use test::{black_box, Bencher};

    #[test]
    fn ticker_from_str_advanced() {
        assert_eq!(Ticker::from_str("btc_usd").unwrap(), t!(btc-usd));
        assert_eq!(Ticker::from_str("btc-usd").unwrap(), t!(btc-usd));
        assert_eq!(Ticker::from_str("btc/usd").unwrap(), t!(btc-usd));

        assert_eq!(Ticker::from_str("BTC_USD").unwrap(), t!(btc-usd));
        assert_eq!(Ticker::from_str("BTC-USD").unwrap(), t!(btc-usd));
        assert_eq!(Ticker::from_str("BTC/USD").unwrap(), t!(btc-usd));
        assert_eq!(Ticker::from_str("USD_BTC").unwrap(), t!(usd-btc));

        assert!(Ticker::from_str("not_a_ticker_format").is_err());
    }

    #[test]
    fn it_parses_bcn_ticker() {
        let ticker = Ticker::from_str("bcn_btc").unwrap();
    }

    #[test]
    fn it_checks_simple_macro_use() {
        let btc_cur = c!(btc);
        assert_eq!(btc_cur, Currency::btc);


        let plnx_exch = e!(plnx);
        assert_eq!(plnx_exch, Exchange::plnx);

        let eth_usd_ticker = t!(eth-usd);
        assert_eq!(eth_usd_ticker.base, c!(eth));
        assert_eq!(eth_usd_ticker.quote, c!(usd));
    }

    #[cfg(feature = "unstable")]
    #[bench]
    fn ticker_to_str_obfuscated(b: &mut Bencher) {
        let ticker = Ticker::from_str("btc_usd").unwrap();
        b.iter(|| {
            black_box(ticker.as_str())
        });
    }

    #[cfg(feature = "unstable")]
    #[bench]
    fn ticker_from_str_bench(b: &mut Bencher) {
        let t = black_box(String::from("btc_usd"));
        b.iter(||{
            Ticker::from_str(&t).unwrap()
        });
    }

    #[cfg(feature = "unstable")]
    #[bench]
    fn ticker_from_str_bench_last(b: &mut Bencher) {
        let t = black_box(String::from("ltc_cad"));
        b.iter(||{
            Ticker::from_str(&t).unwrap()
        });
    }

    #[cfg(feature = "unstable")]
    #[bench]
    fn ticker_from_str_bench_catchall(b: &mut Bencher) {
        let t = black_box(String::from("usd_zar"));
        b.iter(||{
            Ticker::from_str(&t).unwrap()
        });
    }

    #[cfg(feature = "unstable")]
    #[bench]
    fn it_converts_ticker_to_u8(b: &mut Bencher) {
        let t = black_box(t!(btc-usd));
        b.iter(|| {
            u8::from(black_box(t))
        });
    }

    #[cfg(feature = "unstable")]
    #[bench]
    fn it_converts_ticker_u8_plus_base_and_quote(b: &mut Bencher) {
        struct A {
            pub ticker: i16,
            pub base: i16,
            pub quote: i16
        }

        let t = black_box(t!(btc-usd));

        b.iter(|| {
            let ticker = u8::from(black_box(t)) as i16;
            let base = u8::from(black_box(t.base)) as i16;
            let quote = u8::from(black_box(t.quote)) as i16;
            A { ticker, base, quote }
        });
    }

    #[test]
    fn it_asserts_that_ticker_takes_up_two_bytes() {
        assert_eq!(::std::mem::size_of::<Ticker>(), 2);
    }

    #[test]
    fn it_checks_a_currency_to_str_return_value() {
        assert_eq!(c!(btc).as_str(), "btc");
    }

    #[cfg(feature = "unstable")]
    #[bench]
    fn ticker_to_string(b: &mut Bencher) {
        let ticker = t!(btc-usd);
        b.iter(|| {
            black_box(ticker.to_string())
        });
    }

    #[cfg(feature = "unstable")]
    #[bench]
    fn ticker_to_s(b: &mut Bencher) {
        let ticker = t!(btc-usd);
        b.iter(|| {
            black_box(ticker.to_s())
        });
    }

    #[cfg(feature = "unstable")]
    #[bench]
    fn ticker_to_str(b: &mut Bencher) {
        let ticker = t!(btc-usd);
        b.iter(|| {
            black_box(ticker.as_str())
        });
    }

    #[cfg(feature = "unstable")]
    #[bench]
    fn currency_to_str(b: &mut Bencher) {
        let usd_currency = c!(usd);
        b.iter(|| {
            usd_currency.as_str()
        });
    }

    #[cfg(feature = "unstable")]
    #[bench]
    fn currency_to_str_uppercase(b: &mut Bencher) {
        let usd_currency = c!(usd);
        b.iter(|| {
            usd_currency.to_str_uppercase()
        });
    }
}