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use rand::random;

use crate::{
    get_init_tvm_stack,
    snippet::{DataType, Snippet},
    Digest, ExecutionState, DIGEST_LENGTH,
};

/// Reverse the order of elements in a digest: [d4, d3, d2, d1, d0] -> [d0, d1, d2, d3, d4]
pub struct ReverseDigest;

impl ReverseDigest {
    fn get_input_state() -> ExecutionState {
        let digest: Digest = random();
        let stack = vec![get_init_tvm_stack(), digest.values().to_vec()].concat();
        ExecutionState::with_stack(stack)
    }
}

impl Snippet for ReverseDigest {
    fn entrypoint(&self) -> String {
        "tasm_hashing_reverse_digest".to_owned()
    }

    fn inputs(&self) -> Vec<String> {
        vec![
            "d4".to_owned(),
            "d3".to_owned(),
            "d2".to_owned(),
            "d1".to_owned(),
            "d0".to_owned(),
        ]
    }

    fn input_types(&self) -> Vec<crate::snippet::DataType> {
        vec![DataType::Digest]
    }

    fn output_types(&self) -> Vec<crate::snippet::DataType> {
        vec![DataType::Digest]
    }

    fn outputs(&self) -> Vec<String> {
        vec![
            "d0".to_owned(),
            "d1".to_owned(),
            "d2".to_owned(),
            "d3".to_owned(),
            "d4".to_owned(),
        ]
    }

    fn stack_diff(&self) -> isize {
        0
    }

    fn function_code(&self, _library: &mut crate::snippet_state::SnippetState) -> String {
        let entrypoint = self.entrypoint();

        format!(
            "
            // BEFORE: _ d4 d3 d2 d1 d0
            // AFTER: _ d0 d1 d2 d3 d4
            {entrypoint}:
                swap 4
                // _ d0 d3 d2 d1 d4
                swap 1
                // _ d0 d3 d2 d4 d1
                swap 3
                // _ d0 d1 d2 d4 d3

                swap 1
                // _ d0 d1 d2 d3 d4

                // _ d0 d1 d2 d3 d4

                return
            "
        )
    }

    fn crash_conditions(&self) -> Vec<String> {
        vec![]
    }

    fn gen_input_states(&self) -> Vec<crate::ExecutionState> {
        vec![Self::get_input_state()]
    }

    fn common_case_input_state(&self) -> crate::ExecutionState {
        Self::get_input_state()
    }

    fn worst_case_input_state(&self) -> crate::ExecutionState {
        Self::get_input_state()
    }

    fn rust_shadowing(
        &self,
        stack: &mut Vec<triton_vm::BFieldElement>,
        _std_in: Vec<triton_vm::BFieldElement>,
        _secret_in: Vec<triton_vm::BFieldElement>,
        _memory: &mut std::collections::HashMap<triton_vm::BFieldElement, triton_vm::BFieldElement>,
    ) {
        let mut elems = vec![];
        for _ in 0..DIGEST_LENGTH {
            elems.push(stack.pop().unwrap())
        }

        for elem in elems {
            stack.push(elem);
        }
    }
}

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

    #[test]
    fn reverse_digest_test() {
        test_rust_equivalence_multiple(&ReverseDigest, true);
    }
}

#[cfg(test)]
mod benches {
    use super::*;
    use crate::snippet_bencher::bench_and_write;

    #[test]
    fn reverse_digest_benchmark() {
        bench_and_write(ReverseDigest);
    }
}