1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

//! ProverResult
use ergotree_ir::serialization::sigma_byte_reader::SigmaByteRead;
use ergotree_ir::serialization::sigma_byte_writer::SigmaByteWrite;
use ergotree_ir::serialization::SigmaParsingError;
use ergotree_ir::serialization::SigmaSerializable;
use ergotree_ir::serialization::SigmaSerializeResult;

use super::ContextExtension;
use std::convert::TryFrom;

/// Serialized proof generated by ['Prover']
#[derive(PartialEq, Eq, Hash, Debug, Clone)]
pub enum ProofBytes {
    /// Empty proof
    Empty,
    /// Non-empty proof
    Some(Vec<u8>),
}

impl ProofBytes {
    /// Returns bytes or empty vector if empty
    pub fn to_bytes(self) -> Vec<u8> {
        match self {
            ProofBytes::Empty => Vec::new(),
            ProofBytes::Some(bytes) => bytes,
        }
    }
}

impl From<ProofBytes> for Vec<u8> {
    fn from(v: ProofBytes) -> Self {
        match v {
            ProofBytes::Empty => Vec::new(),
            ProofBytes::Some(bytes) => bytes,
        }
    }
}

impl From<Vec<u8>> for ProofBytes {
    fn from(bytes: Vec<u8>) -> Self {
        if bytes.is_empty() {
            ProofBytes::Empty
        } else {
            ProofBytes::Some(bytes)
        }
    }
}

// for JSON encoding in ergo-lib as Base16-encoded string
impl From<ProofBytes> for String {
    fn from(v: ProofBytes) -> Self {
        match v {
            ProofBytes::Empty => "".to_string(),
            ProofBytes::Some(bytes) => base16::encode_lower(&bytes),
        }
    }
}

// for JSON encoding in ergo-lib
impl TryFrom<String> for ProofBytes {
    type Error = base16::DecodeError;

    fn try_from(value: String) -> Result<Self, Self::Error> {
        base16::decode(&value).map(|bytes| bytes.into())
    }
}

impl AsRef<[u8]> for ProofBytes {
    fn as_ref(&self) -> &[u8] {
        match self {
            ProofBytes::Empty => &[],
            ProofBytes::Some(bytes) => bytes.as_ref(),
        }
    }
}

impl SigmaSerializable for ProofBytes {
    fn sigma_serialize<W: SigmaByteWrite>(&self, w: &mut W) -> SigmaSerializeResult {
        match self {
            ProofBytes::Empty => w.put_u16(0)?,
            ProofBytes::Some(bytes) => {
                w.put_u16(bytes.len() as u16)?;
                w.write_all(bytes)?;
            }
        }
        Ok(())
    }

    fn sigma_parse<R: SigmaByteRead>(r: &mut R) -> Result<Self, SigmaParsingError> {
        let proof_len = r.get_u16()?;
        Ok(if proof_len == 0 {
            ProofBytes::Empty
        } else {
            let mut bytes = vec![0; proof_len as usize];
            r.read_exact(&mut bytes)?;
            ProofBytes::Some(bytes)
        })
    }
}

/// Proof of correctness of tx spending
#[derive(Debug, PartialEq, Eq, Clone)]
pub struct ProverResult {
    /// proof that satisfies final sigma proposition
    pub proof: ProofBytes,
    /// user-defined variables to be put into context
    pub extension: ContextExtension,
}

#[cfg(feature = "arbitrary")]
/// Arbitrary impl
mod arbitrary {
    use super::*;
    use proptest::{collection::vec, prelude::*};

    impl Arbitrary for ProofBytes {
        type Parameters = ();
        type Strategy = BoxedStrategy<Self>;

        fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
            prop_oneof![
                Just(ProofBytes::Empty),
                (vec(any::<u8>(), 32..100))
                    .prop_map(ProofBytes::Some)
                    .boxed()
            ]
            .boxed()
        }
    }
}