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use crate::bytes::Bytes;
use chik_traits::chik_error::{Error, Result};
use chik_traits::Streamable;
use klvm_traits::{FromKlvm, ToKlvm};
use klvmr::allocator::NodePtr;
use klvmr::serde::{node_from_bytes, node_to_bytes, serialized_length_from_bytes};
use klvmr::Allocator;
use sha2::{Digest, Sha256};
use std::io::Cursor;

#[cfg(feature = "py-bindings")]
use chik_traits::{FromJsonDict, ToJsonDict};

#[cfg(feature = "py-bindings")]
use chik_py_streamable_macro::PyStreamable;

#[cfg(feature = "py-bindings")]
use pyo3::prelude::*;

#[cfg_attr(feature = "py-bindings", pyclass, derive(PyStreamable))]
#[derive(Hash, Debug, Clone, Eq, PartialEq)]
pub struct Program(Bytes);

#[cfg(fuzzing)]
impl<'a> arbitrary::Arbitrary<'a> for Program {
    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
        // generate an arbitrary KLVM structure. Not likely a valid program.
        let mut items_left = 1;
        let mut total_items = 0;
        let mut buf = Vec::<u8>::with_capacity(200);

        while items_left > 0 {
            if total_items < 100 && u.ratio(1, 4).unwrap() {
                // make a pair
                buf.push(0xff);
                items_left += 2;
            } else {
                // make an atom. just single bytes for now
                buf.push(u.int_in_range(0..=0x80).unwrap());
            }
            total_items += 1;
            items_left -= 1;
        }
        Ok(Self(buf.into()))
    }
}

impl Program {
    pub fn len(&self) -> usize {
        self.0.len()
    }

    pub fn is_empty(&self) -> bool {
        self.0.is_empty()
    }

    pub fn as_slice(&self) -> &[u8] {
        self.0.as_slice()
    }
}

impl Streamable for Program {
    fn update_digest(&self, digest: &mut Sha256) {
        digest.update(&self.0);
    }

    fn stream(&self, out: &mut Vec<u8>) -> Result<()> {
        out.extend_from_slice(self.0.as_ref());
        Ok(())
    }

    fn parse(input: &mut Cursor<&[u8]>) -> Result<Self> {
        let pos = input.position();
        let buf: &[u8] = &input.get_ref()[pos as usize..];
        let len = serialized_length_from_bytes(buf).map_err(|_e| Error::EndOfBuffer)?;
        if buf.len() < len as usize {
            return Err(Error::EndOfBuffer);
        }
        let program = buf[..len as usize].to_vec();
        input.set_position(pos + len);
        Ok(Program(program.into()))
    }
}

#[cfg(feature = "py-bindings")]
impl ToJsonDict for Program {
    fn to_json_dict(&self, py: Python) -> PyResult<PyObject> {
        self.0.to_json_dict(py)
    }
}

#[cfg(feature = "py-bindings")]
impl FromJsonDict for Program {
    fn from_json_dict(o: &PyAny) -> PyResult<Self> {
        let bytes = Bytes::from_json_dict(o)?;
        let len =
            serialized_length_from_bytes(bytes.as_slice()).map_err(|_e| Error::EndOfBuffer)?;
        if len as usize != bytes.len() {
            // If the bytes in the JSON string is not a valid KLVM
            // serialization, or if it has garbage at the end of the string,
            // reject it
            return Err(Error::InvalidKlvm)?;
        }
        Ok(Self(bytes))
    }
}

impl FromKlvm for Program {
    fn from_klvm(a: &Allocator, ptr: NodePtr) -> klvm_traits::Result<Self> {
        Ok(Self(
            node_to_bytes(a, ptr)
                .map_err(|error| klvm_traits::Error::Custom(error.to_string()))?
                .into(),
        ))
    }
}

impl ToKlvm for Program {
    fn to_klvm(&self, a: &mut Allocator) -> klvm_traits::Result<NodePtr> {
        node_from_bytes(a, self.0.as_ref())
            .map_err(|error| klvm_traits::Error::Custom(error.to_string()))
    }
}

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

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn program_roundtrip() {
        let a = &mut Allocator::new();
        let expected = "ff01ff02ff62ff0480";
        let expected_bytes = hex::decode(expected).unwrap();

        let ptr = node_from_bytes(a, &expected_bytes).unwrap();
        let program = Program::from_klvm(a, ptr).unwrap();

        let round_trip = program.to_klvm(a).unwrap();
        assert_eq!(expected, hex::encode(node_to_bytes(a, round_trip).unwrap()));
    }
}