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
131
132
133
134
135
136
137
138
139
140
141
142
143

// Copyright (c) 2022-2023 Yuki Kishimoto
// Copyright (c) 2023-2024 Rust Nostr Developers
// Distributed under the MIT software license

//! Nostr Zapper

#![warn(missing_docs)]
#![warn(rustdoc::bare_urls)]
#![allow(unknown_lints)]

use core::fmt;
use std::sync::Arc;

pub extern crate nostr;

pub use async_trait::async_trait;
use nostr::prelude::*;

pub mod error;
pub mod prelude;

pub use self::error::ZapperError;

/// Backend
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ZapperBackend {
    /// WebLN
    WebLN,
    /// Nostr Wallet Connect
    NWC,
    /// Custom
    Custom(String),
}

/// A type-erased [`NostrZapper`].
pub type DynNostrZapper = dyn NostrZapper<Err = ZapperError>;

/// A type that can be type-erased into `Arc<dyn NostrZapper>`.
pub trait IntoNostrZapper {
    #[doc(hidden)]
    fn into_nostr_zapper(self) -> Arc<DynNostrZapper>;
}

impl IntoNostrZapper for Arc<DynNostrZapper> {
    fn into_nostr_zapper(self) -> Arc<DynNostrZapper> {
        self
    }
}

impl<T> IntoNostrZapper for T
where
    T: NostrZapper + Sized + 'static,
{
    fn into_nostr_zapper(self) -> Arc<DynNostrZapper> {
        Arc::new(EraseNostrZapperError(self))
    }
}

// Turns a given `Arc<T>` into `Arc<DynNostrZapper>` by attaching the
// NostrZapper impl vtable of `EraseNostrZapperError<T>`.
impl<T> IntoNostrZapper for Arc<T>
where
    T: NostrZapper + 'static,
{
    fn into_nostr_zapper(self) -> Arc<DynNostrZapper> {
        let ptr: *const T = Arc::into_raw(self);
        let ptr_erased = ptr as *const EraseNostrZapperError<T>;
        // SAFETY: EraseNostrZapperError is repr(transparent) so T and
        //         EraseNostrZapperError<T> have the same layout and ABI
        unsafe { Arc::from_raw(ptr_erased) }
    }
}

/// Nostr Database
#[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
#[cfg_attr(not(target_arch = "wasm32"), async_trait)]
pub trait NostrZapper: AsyncTraitDeps {
    /// Error
    type Err: From<ZapperError> + Into<ZapperError>;

    /// Name of the backend zapper used (ex. WebLN, NWC, ...)
    fn backend(&self) -> ZapperBackend;

    /// Pay invoice
    async fn pay(&self, invoice: String) -> Result<(), Self::Err>;
}

#[repr(transparent)]
struct EraseNostrZapperError<T>(T);

impl<T: fmt::Debug> fmt::Debug for EraseNostrZapperError<T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        self.0.fmt(f)
    }
}

#[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
#[cfg_attr(not(target_arch = "wasm32"), async_trait)]
impl<T: NostrZapper> NostrZapper for EraseNostrZapperError<T> {
    type Err = ZapperError;

    fn backend(&self) -> ZapperBackend {
        self.0.backend()
    }

    async fn pay(&self, invoice: String) -> Result<(), Self::Err> {
        self.0.pay(invoice).await.map_err(Into::into)
    }
}

/// Alias for `Send` on non-wasm, empty trait (implemented by everything) on
/// wasm.
#[cfg(not(target_arch = "wasm32"))]
pub trait SendOutsideWasm: Send {}
#[cfg(not(target_arch = "wasm32"))]
impl<T: Send> SendOutsideWasm for T {}

/// Alias for `Send` on non-wasm, empty trait (implemented by everything) on
/// wasm.
#[cfg(target_arch = "wasm32")]
pub trait SendOutsideWasm {}
#[cfg(target_arch = "wasm32")]
impl<T> SendOutsideWasm for T {}

/// Alias for `Sync` on non-wasm, empty trait (implemented by everything) on
/// wasm.
#[cfg(not(target_arch = "wasm32"))]
pub trait SyncOutsideWasm: Sync {}
#[cfg(not(target_arch = "wasm32"))]
impl<T: Sync> SyncOutsideWasm for T {}

/// Alias for `Sync` on non-wasm, empty trait (implemented by everything) on
/// wasm.
#[cfg(target_arch = "wasm32")]
pub trait SyncOutsideWasm {}
#[cfg(target_arch = "wasm32")]
impl<T> SyncOutsideWasm for T {}

/// Super trait that is used for our store traits, this trait will differ if
/// it's used on WASM. WASM targets will not require `Send` and `Sync` to have
/// implemented, while other targets will.
pub trait AsyncTraitDeps: std::fmt::Debug + SendOutsideWasm + SyncOutsideWasm {}
impl<T: std::fmt::Debug + SendOutsideWasm + SyncOutsideWasm> AsyncTraitDeps for T {}