ergotree-ir 0.22.0

use std::convert::TryFrom;

use crate::serialization::op_code::OpCode;
use crate::serialization::sigma_byte_reader::SigmaByteRead;
use crate::serialization::sigma_byte_writer::SigmaByteWrite;
use crate::serialization::SigmaParsingError;
use crate::serialization::SigmaSerializable;
use crate::serialization::SigmaSerializeResult;
use crate::types::stuple::STuple;
use crate::types::stype::SType;

use super::expr::Expr;
use super::expr::InvalidArgumentError;
use crate::has_opcode::HasStaticOpCode;

/// Tuple field access index (1..=255)
#[derive(PartialEq, Eq, Debug, Copy, Clone)]
pub struct TupleFieldIndex(u8);

/// Error for tuple index being out of bounds (1..=255)
#[derive(Debug)]
pub struct TupleFieldIndexOutBounds;

impl TryFrom<u8> for TupleFieldIndex {
    type Error = TupleFieldIndexOutBounds;

    fn try_from(value: u8) -> Result<Self, Self::Error> {
        if value >= 1 {
            Ok(TupleFieldIndex(value))
        } else {
            Err(TupleFieldIndexOutBounds)
        }
    }
}

impl TupleFieldIndex {
    /// Returns a zero-based index
    pub fn zero_based_index(&self) -> usize {
        (self.0 - 1) as usize
    }
}

impl SigmaSerializable for TupleFieldIndex {
    fn sigma_serialize<W: SigmaByteWrite>(&self, w: &mut W) -> SigmaSerializeResult {
        w.put_u8(self.0)?;
        Ok(())
    }

    fn sigma_parse<R: SigmaByteRead>(r: &mut R) -> Result<Self, SigmaParsingError> {
        let field_index = r.get_u8()?;
        TupleFieldIndex::try_from(field_index).map_err(|_| {
            SigmaParsingError::ValueOutOfBounds(format!(
                "invalid tuple field index: {0}",
                field_index
            ))
        })
    }
}

/// Select a field of the tuple value
#[derive(PartialEq, Eq, Debug, Clone)]
pub struct SelectField {
    /// Tuple value
    pub input: Box<Expr>,
    /// 1-based tuple field index (input._1 has field_index of 1)
    pub field_index: TupleFieldIndex,
    /// Field type
    field_tpe: SType,
}

impl SelectField {
    /// Create new object, returns an error if any of the requirements failed
    pub fn new(input: Expr, field_index: TupleFieldIndex) -> Result<Self, InvalidArgumentError> {
        match input.tpe() {
            SType::STuple(STuple { items }) => {
                if let Some(field_tpe) = items.get(field_index.zero_based_index()) {
                    Ok(SelectField {
                        input: Box::new(input),
                        field_index,
                        field_tpe: field_tpe.clone(),
                    })
                } else {
                    Err(InvalidArgumentError(format!(
                        "SelectField field index is out of bounds {0:?}, tuple type: {1:?}",
                        field_index,
                        input.tpe()
                    )))
                }
            }
            tpe => Err(InvalidArgumentError(format!(
                "expected SelectField input type to be STuple, got {0:?}",
                tpe
            ))),
        }
    }
}

impl HasStaticOpCode for SelectField {
    const OP_CODE: OpCode = OpCode::SELECT_FIELD;
}

impl SelectField {
    /// Type
    pub fn tpe(&self) -> SType {
        self.field_tpe.clone()
    }
}

impl SigmaSerializable for SelectField {
    fn sigma_serialize<W: SigmaByteWrite>(&self, w: &mut W) -> SigmaSerializeResult {
        self.input.sigma_serialize(w)?;
        self.field_index.sigma_serialize(w)
    }

    fn sigma_parse<R: SigmaByteRead>(r: &mut R) -> Result<Self, SigmaParsingError> {
        let input = Expr::sigma_parse(r)?;
        let field_index = TupleFieldIndex::sigma_parse(r)?;
        Ok(SelectField::new(input, field_index)?)
    }
}

#[cfg(test)]
#[cfg(feature = "arbitrary")]
#[allow(clippy::unwrap_used)]
mod tests {
    use std::convert::TryInto;

    use crate::serialization::sigma_serialize_roundtrip;

    use super::*;

    #[test]
    fn ser_roundtrip() {
        let e: Expr = SelectField::new(Expr::Const((1i64, true).into()), 1u8.try_into().unwrap())
            .unwrap()
            .into();
        assert_eq![sigma_serialize_roundtrip(&e), e];
    }
}