use std::{
    cmp::Ordering,
    fmt,
    hash::{Hash, Hasher},
    io::{self, Error, ErrorKind},
    str::FromStr,
    string::String,
};

use lazy_static::lazy_static;
use serde::{self, Deserialize, Deserializer, Serialize, Serializer};
use zerocopy::{AsBytes, FromBytes, Unaligned};

use crate::{formatting, key::address};

pub const ID_LEN: usize = 20;

lazy_static! {
    static ref EMPTY: Vec<u8> = vec![0; ID_LEN];
}

/// ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/ids#ShortID
/// ref. https://docs.rs/zerocopy/latest/zerocopy/trait.AsBytes.html#safety
#[derive(Debug, Deserialize, Clone, Eq, AsBytes, FromBytes, Unaligned)]
#[repr(transparent)]
pub struct Id([u8; ID_LEN]);

impl Default for Id {
    fn default() -> Self {
        Self::default()
    }
}

impl Id {
    pub fn default() -> Self {
        Id([0; ID_LEN])
    }

    pub fn empty() -> Self {
        Id([0; ID_LEN])
    }

    pub fn is_empty(&self) -> bool {
        (*self) == Self::empty()
    }

    pub fn from_slice(d: &[u8]) -> Self {
        assert!(d.len() <= ID_LEN);
        let mut d: Vec<u8> = Vec::from(d);
        if d.len() < ID_LEN {
            d.resize(ID_LEN, 0);
        }
        let d: [u8; ID_LEN] = d.try_into().unwrap();
        Id(d)
    }

    /// "hashing.PubkeyBytesToAddress"
    /// ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/utils/hashing#PubkeyBytesToAddress
    pub fn from_public_key_bytes<S>(pub_key_bytes: S) -> io::Result<Self>
    where
        S: AsRef<[u8]>,
    {
        let hashed = address::hash_sha256_ripemd160(pub_key_bytes)?;

        // "ids.Id.String"
        // ref. https://pkg.go.dev/github.com/ava-labs/avalanchego/ids#Id.String
        let encoded = formatting::encode_cb58_with_checksum(&hashed);
        Self::from_str(&encoded)
    }
}

impl AsRef<[u8]> for Id {
    fn as_ref(&self) -> &[u8] {
        &self.0
    }
}

/// ref. https://doc.rust-lang.org/std/string/trait.ToString.html
/// ref. https://doc.rust-lang.org/std/fmt/trait.Display.html
/// Use "Self.to_string()" to directly invoke this
impl fmt::Display for Id {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let s = formatting::encode_cb58_with_checksum(&self.0);
        write!(f, "{}", s)
    }
}

/// ref. https://doc.rust-lang.org/std/str/trait.FromStr.html
impl FromStr for Id {
    type Err = Error;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let decoded = formatting::decode_cb58_with_checksum(s).map_err(|e| {
            Error::new(
                ErrorKind::Other,
                format!("failed decode_cb58_with_checksum '{}'", e),
            )
        })?;
        Ok(Self::from_slice(&decoded))
    }
}

/// ref. https://serde.rs/impl-serialize.html
impl Serialize for Id {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        serializer.serialize_str(&self.to_string())
    }
}

fn fmt_id<'de, D>(deserializer: D) -> Result<Id, D::Error>
where
    D: Deserializer<'de>,
{
    let s = String::deserialize(deserializer)?;
    Id::from_str(&s).map_err(serde::de::Error::custom)
}

pub fn deserialize_id<'de, D>(deserializer: D) -> Result<Option<Id>, D::Error>
where
    D: Deserializer<'de>,
{
    #[derive(Deserialize)]
    struct Wrapper(#[serde(deserialize_with = "fmt_id")] Id);
    let v = Option::deserialize(deserializer)?;
    Ok(v.map(|Wrapper(a)| a))
}

pub fn must_deserialize_id<'de, D>(deserializer: D) -> Result<Id, D::Error>
where
    D: Deserializer<'de>,
{
    #[derive(Deserialize)]
    struct Wrapper(#[serde(deserialize_with = "fmt_id")] Id);
    let v = Option::deserialize(deserializer)?;
    match v.map(|Wrapper(a)| a) {
        Some(unwrapped) => Ok(unwrapped),
        None => Err(serde::de::Error::custom(
            "empty short::Id from deserialization",
        )),
    }
}

/// RUST_LOG=debug cargo test --package avalanche-types --lib -- ids::short::test_id --exact --show-output
#[test]
fn test_id() {
    let id = Id::from_slice(&<Vec<u8>>::from([
        0x3d, 0x0a, 0xd1, 0x2b, 0x8e, 0xe8, 0x92, 0x8e, 0xdf, 0x24, //
        0x8c, 0xa9, 0x1c, 0xa5, 0x56, 0x00, 0xfb, 0x38, 0x3f, 0x07, //
    ]));
    assert_eq!(id.to_string(), "6ZmBHXTqjknJoZtXbnJ6x7af863rXDTwx");
    let id_from_str = Id::from_str("6ZmBHXTqjknJoZtXbnJ6x7af863rXDTwx").unwrap();
    assert_eq!(id, id_from_str);
}

impl Ord for Id {
    fn cmp(&self, other: &Id) -> Ordering {
        self.0.cmp(&(other.0))
    }
}

impl PartialOrd for Id {
    fn partial_cmp(&self, other: &Id) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl PartialEq for Id {
    fn eq(&self, other: &Id) -> bool {
        self.cmp(other) == Ordering::Equal
    }
}

/// ref. https://rust-lang.github.io/rust-clippy/master/index.html#derive_hash_xor_eq
impl Hash for Id {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.0.hash(state);
    }
}

#[derive(Eq)]
pub struct Ids(Vec<Id>);

impl Ids {
    pub fn new(ids: &[Id]) -> Self {
        Ids(Vec::from(ids))
    }
}

impl Ord for Ids {
    fn cmp(&self, other: &Ids) -> Ordering {
        // packer encodes the array length first
        // so if the lengths differ, the ordering is decided
        let l1 = self.0.len();
        let l2 = other.0.len();
        l1.cmp(&l2) // returns when lengths are not Equal
            .then_with(
                || self.0.cmp(&other.0), // if lengths are Equal, compare the ids
            )
    }
}

impl PartialOrd for Ids {
    fn partial_cmp(&self, other: &Ids) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl PartialEq for Ids {
    fn eq(&self, other: &Ids) -> bool {
        self.cmp(other) == Ordering::Equal
    }
}

/// RUST_LOG=debug cargo test --package avalanche-types --lib -- ids::short::test_sort --exact --show-output
#[test]
fn test_sort() {
    // lengths of individual ids do not matter since all are fixed-sized
    let id1 = Id::from_slice(&<Vec<u8>>::from([0x01, 0x00, 0x00, 0x00]));
    let id2 = Id::from_slice(&<Vec<u8>>::from([0x01, 0x00, 0x00, 0x00, 0x00]));
    assert!(id1 == id2);

    // lengths of individual ids do not matter since all are fixed-sized
    let id1 = Id::from_slice(&<Vec<u8>>::from([0x01, 0x00, 0x00, 0x00, 0x00]));
    let id2 = Id::from_slice(&<Vec<u8>>::from([0x02]));
    assert!(id1 < id2);

    // lengths of individual ids do not matter since all are fixed-sized
    let id1 = Id::from_slice(&<Vec<u8>>::from([0x02, 0x00, 0x00, 0x00, 0x00]));
    let id2 = Id::from_slice(&<Vec<u8>>::from([0x01, 0x00, 0x00, 0x00, 0x00]));
    assert!(id1 > id2);

    // lengths of Id matter
    let ids1 = Ids(vec![
        Id::from_slice(&<Vec<u8>>::from([0x01])),
        Id::from_slice(&<Vec<u8>>::from([0x02])),
        Id::from_slice(&<Vec<u8>>::from([0x03])),
    ]);
    let ids2 = Ids(vec![
        Id::from_slice(&<Vec<u8>>::from([0x01])),
        Id::from_slice(&<Vec<u8>>::from([0x02])),
        Id::from_slice(&<Vec<u8>>::from([0x03])),
    ]);
    assert!(ids1 == ids2);

    // lengths of Id matter
    let ids1 = Ids(vec![
        Id::from_slice(&<Vec<u8>>::from([0x05])),
        Id::from_slice(&<Vec<u8>>::from([0x06])),
        Id::from_slice(&<Vec<u8>>::from([0x07])),
    ]);
    let ids2 = Ids(vec![
        Id::from_slice(&<Vec<u8>>::from([0x01])),
        Id::from_slice(&<Vec<u8>>::from([0x02])),
        Id::from_slice(&<Vec<u8>>::from([0x03])),
        Id::from_slice(&<Vec<u8>>::from([0x04])),
    ]);
    assert!(ids1 < ids2);

    // lengths of Id matter
    let ids1 = Ids(vec![
        Id::from_slice(&<Vec<u8>>::from([0x01])),
        Id::from_slice(&<Vec<u8>>::from([0x02])),
        Id::from_slice(&<Vec<u8>>::from([0x03])),
        Id::from_slice(&<Vec<u8>>::from([0x04])),
    ]);
    let ids2 = Ids(vec![
        Id::from_slice(&<Vec<u8>>::from([0x09])),
        Id::from_slice(&<Vec<u8>>::from([0x09])),
        Id::from_slice(&<Vec<u8>>::from([0x09])),
    ]);
    assert!(ids1 > ids2);

    // lengths of Id matter
    let ids1 = Ids(vec![
        Id::from_slice(&<Vec<u8>>::from([0x01])),
        Id::from_slice(&<Vec<u8>>::from([0x02])),
        Id::from_slice(&<Vec<u8>>::from([0x03])),
    ]);
    let ids2 = Ids(vec![
        Id::from_slice(&<Vec<u8>>::from([0x01])),
        Id::from_slice(&<Vec<u8>>::from([0x02])),
        Id::from_slice(&<Vec<u8>>::from([0x05])),
    ]);
    assert!(ids1 < ids2);

    let mut ids1 = vec![
        Id::from_slice(&<Vec<u8>>::from([0x03])),
        Id::from_slice(&<Vec<u8>>::from([0x02])),
        Id::from_slice(&<Vec<u8>>::from([0x01])),
    ];
    ids1.sort();
    let ids2 = vec![
        Id::from_slice(&<Vec<u8>>::from([0x01])),
        Id::from_slice(&<Vec<u8>>::from([0x02])),
        Id::from_slice(&<Vec<u8>>::from([0x03])),
    ];
    assert!(ids1 == ids2);
}