//! ## A (de)serializer for RLP encoding in ETH
//! 
//! ### Not Supported Types 
//! 
//! - bool
//! - float numbers
//! - maps
//! - enum (only deserialize)
//! 
//! We do not support enum when deserializing because we lost some information (i.e. variant //! index) about the original value when serializing.
//! 
//! We have to choose this approach because there is no enums in Golang while ETH is written in go. Treating enums as a transparent layer can make our furture implementation compatiable with ETH.
//! 
//! ### Design principle
//! 
//! Accroding to the ETH Yellow Paper, all supported data structure can be represented with either recursive list of byte arrays ![](https://latex.codecogs.com/svg.latex?\mathbb{L}) or byte arrays ![](https://latex.codecogs.com/svg.latex?\mathbb{B}). So we can transform all Rust's compound types, for example, tuple, struct and list, into lists. And then encode them as exactly described in the paper
//! 
//! For example, the structure in `test::test_embeded_struct`, can be internally treated as the following form:
//! 
//! ```
//! [
//!     "This is a tooooooooooooo loooooooooooooooooooong tag", 
//!     [
//!         114514, 
//!         [191, -9810], 
//!         [
//!             [[], [[]], [[], [[]]]]
//!         ]
//!     ], 
//!     "哼.啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊"
//! ]
//! ```
//! 
//! ### ZST serialization
//! 
//! In Rust, we can represent 'empty' in many ways, for example:
//! 
//! ```
//! [], (), "", b"", struct Empty, Variant::Empty, None, PhantomData<T>
//! ```
//! 
//! In out implementation:
//! 
//! 1. `[]` and `()` are considered empty list, thus should be serialized into 0xc0
//! 2. All other ZSTs are considered empty, thus should be serialized into 0x80
//! 
//! To better understand ZSTs' behavior when serializing, try this code:
//! 
//! ```rust
//! #[test]
//! fn test_compound_zst() {
//!     #[derive(Serialize, Debug, PartialEq, Eq)]
//!     struct ZST;
//! 
//!     #[derive(Serialize, Debug, PartialEq, Eq)]
//!     enum Simple {
//!         Empty(ZST),
//!         #[allow(dead_code)]
//!         Int((u32, u64))
//!     }
//! 
//!     #[derive(Serialize, Debug, PartialEq, Eq)]
//!     struct ContainZST(Simple);
//! 
//!     #[derive(Serialize, Debug, PartialEq, Eq)]
//!     struct StructZST {
//!         zst: Simple
//!     }
//! 
//!     let zst = Simple::Empty(ZST);
//!     let zst_res = to_bytes(&zst).unwrap();
//!     assert_eq!(zst_res, [0x80]);
//! 
//!     let with_zst = ContainZST(Simple::Empty(ZST));
//!     let with_zst_res = to_bytes(&with_zst).unwrap();
//!     // the container is transparent because its a newtype
//!     assert_eq!(with_zst_res, [0x80]);
//!     
//!     let with_zst = StructZST { zst: Simple::Empty(ZST) };
//!     let with_zst_res = to_bytes(&with_zst).unwrap();
//!     // the container is a list, to this is equivlent to [""]
//!     assert_eq!(with_zst_res, [0xc1, 0x80]);
//!     }
//! ```
//! 
//! ### RLP Proxy 
//! 
//! We have a `RlpProxy` struct that implemented `Deserialize` trait, which just stores the original rlp encoded data after deserialization (no matter what type it is). You can gain more control over the deserialization process with it. Check out `de::RlpProxy` to find more about it.
//! 
//! ### (de)serializers for frequently used types
//! 
//! We provide two (de)serializers for frequently used types in blockchain.
//! 
//! - `biguint` for `num_bigint::BigUint`
//! - `byte_array` for `[u8; N]`
//! 
//! Put `#[serde(with = "biguint")]` or `#[serde(with = "byte_array")]` before your struct **field** to use them.


pub mod ser;
pub mod error;
pub mod rlp;
pub mod de;
pub mod types;

#[cfg(test)]
mod test {
    use num_bigint::BigUint;
    use serde::{Serialize, Deserialize};
    use serde_bytes::Bytes;
    use hex;

    use crate::de::RlpProxy;
    use crate::rlp::to_bytes;
    use crate::rlp::from_bytes;
    use crate::types::{biguint, byte_array};

    /// The transcation is the #0 transcation of 
    /// https://api.etherscan.io/api?module=proxy&action=eth_getBlockByNumber&tag=0xa1a489&boolean=true&apikey=YourApiKeyToken
    /// The encoded data is from README of 
    /// https://github.com/zhangchiqing/merkle-patricia-trie
    #[test]
    fn test_bn() {
        #[derive(Serialize, Deserialize, PartialEq, Eq, Debug)]
        struct LegacyTx {
            nonce: u64,
            #[serde(with = "biguint")]
            gas_price: BigUint,
            gas_limit: u64,
            #[serde(with = "byte_array")]
            to: [u8; 20],
            #[serde(with = "biguint")]
            value: BigUint,
            #[serde(with = "serde_bytes")]
            data: Vec<u8>,
            #[serde(with = "biguint")]
            v: BigUint,
            #[serde(with = "biguint")]
            r: BigUint,
            #[serde(with = "biguint")]
            s: BigUint
        }

        let mut to = [0; 20];
        to.copy_from_slice(&hex::decode("a3bed4e1c75d00fa6f4e5e6922db7261b5e9acd2").unwrap());

        let bn = |s| BigUint::from_bytes_be(&hex::decode(s).unwrap());
        
        let tx = LegacyTx {
            nonce: 0xa5,
            gas_price: bn("2e90edd000"),
            gas_limit: 0x12bc2,
            to,
            value: bn("00"),
            data: hex::decode("a9059cbb0000000000000000000000008bda8b9823b8490e8cf220dc7b91d97da1c54e250000000000000000000000000000000000000000000000056bc75e2d63100000").unwrap(),
            v: bn("26"),
            r: bn("6c89b57113cf7da8aed7911310e03d49be5e40de0bd73af4c9c54726c478691b"),
            s: bn("56223f039fab98d47c71f84190cf285ce8fc7d9181d6769387e5efd0a970e2e9")
        };

        let expected = "f8ab81a5852e90edd00083012bc294a3bed4e1c75d00fa6f4e5e6922db7261b5e9acd280b844a9059cbb0000000000000000000000008bda8b9823b8490e8cf220dc7b91d97da1c54e250000000000000000000000000000000000000000000000056bc75e2d6310000026a06c89b57113cf7da8aed7911310e03d49be5e40de0bd73af4c9c54726c478691ba056223f039fab98d47c71f84190cf285ce8fc7d9181d6769387e5efd0a970e2e9";

        let encoded = to_bytes(&tx).unwrap();
        let orig: LegacyTx = from_bytes(&encoded).unwrap();
        assert_eq!(orig, tx);
        assert_eq!(hex::encode(encoded), expected);
    }

    #[test]
    fn test_proxy() {
        #[derive(Serialize, Deserialize, PartialEq, Eq, Debug)]
        #[serde(from = "RlpProxy")]
        enum Classify {
            Zero(u8),
            One(u8),
            Ten((u8, u8))
        }
        
        impl From<RlpProxy> for Classify {
            fn from(proxy: RlpProxy) -> Self {
                let raw = proxy.raw();
                let mut tree = proxy.rlp_tree();
                if tree.value_count() == 2 {
                    return Classify::Ten(from_bytes(raw).unwrap())
                }

                let val = tree.next().unwrap()[0];
                match val {
                    0 => Classify::Zero(0),
                    1 => Classify::One(1),
                    _ => panic!("Value Error.")
                }
            }
        }

        let value = Classify::Ten((12, 34));
        let encoded = to_bytes(&value).unwrap();
        let origin = from_bytes(&encoded).unwrap();

        assert_eq!(value, origin);
    }

    #[test]
    fn test_long_string() {
        #[derive(Serialize, Deserialize, PartialEq, Eq, Debug)]
        struct LongStr<'a>(&'a str);

        let long_str = LongStr("Lorem ipsum dolor sit amet, consectetur adipisicing elit");
        let expected: Vec<u8> = [0xb8_u8, 0x38_u8]
            .into_iter()
            .chain(long_str.0.as_bytes().to_owned())
            .collect();
        
        let origin: LongStr = from_bytes(&expected).unwrap();
        assert_eq!(to_bytes(&long_str).unwrap(), expected);
        assert_eq!(long_str, origin);
    }

    #[test]
    fn test_set_theoretic_definition() {
        // [ [], [[]], [ [], [[]] ] ]
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize)]
        struct Three<T>(T);

        let three = Three(((), ((),), ((), ((),))));

        let three_expected = [0xc7, 0xc0, 0xc1, 0xc0, 0xc3, 0xc0, 0xc1, 0xc0];
        let origin: Three<((), ((),), ((), ((),)))> = from_bytes(&three_expected).unwrap();
        assert_eq!(to_bytes(&three).unwrap(), three_expected);
        assert_eq!(origin, three)
    }

    #[test]
    fn test_1024() {
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize)]
        struct Int(u16);

        let simp_str = Int(1024);
        let simp_str_expected = [0x82, 0x04, 0x00];
        let origin: Int = from_bytes(&simp_str_expected).unwrap();

        assert_eq!(to_bytes(&simp_str).unwrap(), simp_str_expected);
        assert_eq!(simp_str, origin)
    }

    #[test]
    fn test_15() {
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize)]
        struct Int(u8);

        let simp_str = Int(15);
        let simp_str_expected = [0xf];
        let origin: Int = from_bytes(&simp_str_expected).unwrap();

        assert_eq!(to_bytes(&simp_str).unwrap(), simp_str_expected);
        assert_eq!(origin, simp_str)
    }

    #[test]
    fn test_zero() {
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize)]
        struct Int(u8);

        let simp_str = Int(0);
        let simp_str_expected = [0x80];
        let origin: Int = from_bytes(&simp_str_expected).unwrap();

        assert_eq!(to_bytes(&simp_str).unwrap(), simp_str_expected);
        assert_eq!(origin, simp_str)
    }

    #[test]
    fn test_empty() {
        let simp_str = Bytes::new(b"");
        let simp_str_expected = [0x80];
        let origin: &Bytes = from_bytes(&simp_str_expected).unwrap();

        assert_eq!(to_bytes(&simp_str).unwrap(), simp_str_expected);
        assert_eq!(origin, simp_str)
    }

    #[test]
    fn test_bytes() {
        let simp_str = Bytes::new(b"dog");
        let simp_str_expected = [0x83, b'd', b'o', b'g'];
        let origin: &Bytes = from_bytes(&simp_str_expected).unwrap();

        assert_eq!(to_bytes(&simp_str).unwrap(), simp_str_expected);
        assert_eq!(origin, simp_str)
    }

    #[test]
    fn test_list() {
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize)]
        struct SimpList {
            #[serde(with = "serde_bytes")]
            cat: Vec<u8>,
            #[serde(with = "serde_bytes")]
            dog: Vec<u8>
        }

        let simp_list = SimpList {
            cat: b"cat".to_vec(),
            dog: b"dog".to_vec(),
        };
        let simp_list_expected = [0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g'];
        let origin: SimpList = from_bytes(&simp_list_expected).unwrap();

        assert_eq!(to_bytes(&simp_list).unwrap(), simp_list_expected);
        assert_eq!(origin, simp_list)
    }

    #[test]
    fn test_empty_list() {
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize)]
        struct SimpList {
        }

        let simp_list = SimpList {
        };

        let simp_list_expected = [0xc0];
        let origin: SimpList = from_bytes(&simp_list_expected).unwrap();

        assert_eq!(to_bytes(&simp_list).unwrap(), simp_list_expected);
        assert_eq!(origin, simp_list)
    }

    #[test]
    fn test_boxed_value() {
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize, Clone)]
        struct Boxed {
            a: Box<String>
        }

        let b = Boxed { a: Box::new("dog".into()) };
        let expected = [0xc4, 0x83, b'd', b'o', b'g'];
        let origin: Boxed = from_bytes(&expected).unwrap();

        assert_eq!(origin, b);
        assert_eq!(to_bytes(&b).unwrap(), expected);
    }

    #[test]
    fn test_simple_enum() {
        #[derive(Serialize, Debug, PartialEq, Eq)]
        enum Simple {
            #[allow(dead_code)]
            Empty,
            Int(u32)
        }

        #[derive(Serialize, Debug, PartialEq, Eq)]
        struct Equiv(u32);

        let simple_enum = Simple::Int(114514);
        let equiv = Equiv(114514);

        let enum_res = to_bytes(&simple_enum).unwrap();
        let struct_res = to_bytes(&equiv).unwrap();

        assert_eq!(enum_res, struct_res);
    }

    #[test]
    fn test_unit_variant() {
        #[derive(Serialize, Debug, PartialEq, Eq)]
        enum Simple {
            Empty,
            #[allow(dead_code)]
            Int(u32)
        }

        let unit_variant = Simple::Empty;
        let empty_res = to_bytes(&unit_variant).unwrap();

        assert_eq!(empty_res, [0x80]);
    }

    #[test]
    fn test_variant_tuple() {
        #[derive(Serialize, Debug, PartialEq, Eq)]
        enum Simple {
            #[allow(dead_code)]
            Empty,
            Int((u32, u64))
        }

        #[derive(Serialize, Debug, PartialEq, Eq)]
        struct Equiv((u32, u64));

        let simple_enum = Simple::Int((114514, 1919810));
        let equiv = Equiv((114514, 1919810));

        let enum_res = to_bytes(&simple_enum).unwrap();
        let struct_res = to_bytes(&equiv).unwrap();

        assert_eq!(enum_res, struct_res);
    }

    #[test]
    fn test_compound_zst() {
        #[derive(Serialize, Debug, PartialEq, Eq)]
        struct ZST;

        #[derive(Serialize, Debug, PartialEq, Eq)]
        enum Simple {
            Empty(ZST),
            #[allow(dead_code)]
            Int((u32, u64))
        }

        #[derive(Serialize, Debug, PartialEq, Eq)]
        struct ContainZST(Simple);

        #[derive(Serialize, Debug, PartialEq, Eq)]
        struct StructZST {
            zst: Simple
        }

        let zst = Simple::Empty(ZST);
        let zst_res = to_bytes(&zst).unwrap();
        assert_eq!(zst_res, [0x80]);

        let with_zst = ContainZST(Simple::Empty(ZST));
        let with_zst_res = to_bytes(&with_zst).unwrap();
        // the container is transparent because its a newtype
        assert_eq!(with_zst_res, [0x80]);
        
        let with_zst = StructZST { zst: Simple::Empty(ZST) };
        let with_zst_res = to_bytes(&with_zst).unwrap();
        // the container is a list, to this is equivlent to [""]
        assert_eq!(with_zst_res, [0xc1, 0x80]);
    }

    #[test]
    fn test_variant_struct() {
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize, Clone)]
        struct Third<T> {
            inner: T
        }
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize, Clone)]
        struct Embeding<'a> {
            tag: &'a str,
            ed: Embedded,
            #[serde(with = "serde_bytes")]
            bytes: Vec<u8>
        }
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize, Clone)]
        struct Embedded {
            time: u64,
            out: (u8, u32),
            three: Third<((), ((),), ((), ((),)))>
        }

        #[derive(Serialize, Debug, PartialEq, Eq)]
        enum Simple<'a> {
            #[allow(dead_code)]
            Empty,
            #[allow(dead_code)]
            Int((u32, u64, Embedded)),
            Struct(Embeding<'a>)
        }

        #[derive(Serialize, Debug, PartialEq, Eq)]
        struct Equiv((u32, u64));

        let embed = Embeding {
            tag: "This is a tooooooooooooo loooooooooooooooooooong tag",
            ed: Embedded {
                time: 114514,
                out: (191, 9810),
                three: Third {
                    inner: ((), ((),), ((), ((),)))
                }
            },
            bytes: "哼.啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊".as_bytes().to_vec()
        };

        let simple_enum = Simple::Struct(embed.clone());

        let simple_res = to_bytes(&simple_enum).unwrap();
        let struct_res = to_bytes(&embed).unwrap();

        assert_eq!(simple_res, struct_res);
    }

    #[test]
    fn test_zst_struct() {
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize)]
        struct ZST;

        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize)]
        struct WithZST {
            f1: u8,
            f2: ZST,
            f3: (),
            f4: u8,
        }

        let zst = WithZST {
            f1: 1,
            f2: ZST,
            f3: (),
            f4: 4
        };

        let encoded = to_bytes(&zst).unwrap();
        let origin: WithZST = from_bytes(&encoded).unwrap();
        let expected = [0xc4, 0x1, 0x80, 0xc0, 0x4];
        
        assert_eq!(origin, zst);
        assert_eq!(encoded, expected);
    }

    #[test]
    fn test_embedded_struct() {
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize)]
        struct Third<T> {
            inner: T
        }
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize)]
        struct Embeding<'a> {
            tag: &'a str,
            ed: Embedded,
            #[serde(with = "serde_bytes")]
            bytes: Vec<u8>
        }
        #[derive(Serialize, Debug, PartialEq, Eq, Deserialize)]
        struct Embedded {
            time: u64,
            out: (u8, u32),
            three: Third<((), ((),), ((), ((),)))>
        }

        let embed = Embeding {
            tag: "This is a tooooooooooooo loooooooooooooooooooong tag",
            ed: Embedded {
                time: 114514,
                out: (191, 9810),
                three: Third {
                    inner: ((), ((),), ((), ((),)))
                }
            },
            bytes: "哼.啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊".as_bytes().to_vec()
        };

        let encode = to_bytes(&embed).unwrap();
        let origin: Embeding = from_bytes(&encode).unwrap();
        assert_eq!(embed, origin);
    }

}