jelq

public

an http based roguelike rpg about jelqing

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use axum::{
    Json,
    http::{HeaderValue, Method, StatusCode, header},
    response::{IntoResponse, Response},
};
use serde_json::json;

use super::ctx::Ctx;
use crate::{headers::ACCEPT_PATCH, problem::Problem};

const THERAPY: &str = "Your options are listed in the Allow header. There are more of them than you think. You could also try being honest. It is not in the Allow header because it is not a method.";

pub type Handler<T> = fn(&mut T, &Ctx) -> Response;

/// A predicate for when a method is available, and the refusal when it is not.
type Guard<T> = (fn(&T) -> bool, &'static str);

fn never<T>(_: &T) -> bool {
    false
}

fn unanswered<T>(_: &mut T, _: &Ctx) -> Response {
    StatusCode::METHOD_NOT_ALLOWED.into_response()
}

pub struct Verb<T: 'static> {
    method: &'static str,
    handle: Handler<T>,
    guard: Option<Guard<T>>,
}

impl<T> Verb<T> {
    pub const fn new(method: &'static str, handle: Handler<T>) -> Self {
        Self {
            method,
            handle,
            guard: None,
        }
    }

    /// A method named only to be refused, so that its `405` can say why.
    pub const fn refused(method: &'static str, refusal: &'static str) -> Self {
        Self {
            method,
            handle: unanswered::<T>,
            guard: Some((never::<T>, refusal)),
        }
    }

    pub const fn only_when(self, available: fn(&T) -> bool, refusal: &'static str) -> Self {
        Self {
            guard: Some((available, refusal)),
            ..self
        }
    }

    fn available(&self, target: &T) -> bool {
        self.guard.is_none_or(|(available, _)| available(target))
    }
}

/// The methods a resource supports. `Allow`, `OPTIONS` and `405` are all derived from this list.
pub struct Resource<T: 'static> {
    verbs: &'static [Verb<T>],
    accept_patch: bool,
}

impl<T> Resource<T> {
    pub const fn new(verbs: &'static [Verb<T>]) -> Self {
        Self {
            verbs,
            accept_patch: false,
        }
    }

    pub const fn patchable(verbs: &'static [Verb<T>]) -> Self {
        Self {
            verbs,
            accept_patch: true,
        }
    }

    pub fn allow(&self, target: &T) -> String {
        Self::listed(self.verbs.iter().filter(|verb| verb.available(target)))
    }

    fn listed<'a>(verbs: impl Iterator<Item = &'a Verb<T>>) -> String {
        let mut methods = Vec::new();
        for verb in verbs {
            methods.push(verb.method);
            if verb.method == "GET" {
                methods.push("HEAD");
            }
        }
        methods.push("OPTIONS");
        methods.join(", ")
    }

    pub fn dispatch(&self, target: &mut T, ctx: &Ctx) -> Response {
        let requested = ctx.method().as_str();
        let lookup = if requested == "HEAD" {
            "GET"
        } else {
            requested
        };
        match self.verbs.iter().find(|verb| verb.method == lookup) {
            Some(verb) if verb.available(target) => (verb.handle)(target, ctx),
            Some(verb) => {
                let refusal = verb.guard.map_or("", |(_, refusal)| refusal);
                method_not_allowed(refusal.to_owned(), &self.allow(target))
            }
            None if requested == "OPTIONS" => options(&self.allow(target), self.accept_patch),
            None => unsupported(ctx.method(), &self.allow(target)),
        }
    }
}

fn method_not_allowed(detail: String, allow: &str) -> Response {
    Problem::new(StatusCode::METHOD_NOT_ALLOWED, "method-not-allowed", detail)
        .header(header::ALLOW, allow)
        .into_response()
}

pub fn unsupported(method: &Method, allow: &str) -> Response {
    let name = method.as_str();
    match name {
        "CONNECT" => StatusCode::NOT_IMPLEMENTED.into_response(),
        "BREW" => Problem::new(
            StatusCode::IM_A_TEAPOT,
            "brew",
            "The server is a teapot. RFC 2324 is clear on this. It is not yet short and stout.",
        )
        .into_response(),
        "GET" | "HEAD" | "POST" | "PUT" | "PATCH" | "DELETE" | "OPTIONS" | "TRACE" | "JELQ"
        | "HOLD" => method_not_allowed(format!("{method} is not supported here."), allow),
        _ if name.eq_ignore_ascii_case("jelq") => Problem::new(
            StatusCode::NOT_IMPLEMENTED,
            "not-implemented",
            format!(
                "The server does not implement {method}. Methods are case-sensitive. JELQ is shouted for a reason."
            ),
        )
        .into_response(),
        _ => Problem::new(
            StatusCode::NOT_IMPLEMENTED,
            "not-implemented",
            format!("The server does not implement {method}."),
        )
        .into_response(),
    }
}

fn options(allow: &str, accept_patch: bool) -> Response {
    let mut response = (
        StatusCode::OK,
        [(header::ALLOW, allow)],
        Json(json!({ "detail": THERAPY })),
    )
        .into_response();
    if accept_patch {
        response.headers_mut().insert(
            ACCEPT_PATCH,
            HeaderValue::from_static("application/json-patch+json"),
        );
    }
    response
}

1	use axum::{
2	Json,
3	http::{HeaderValue, Method, StatusCode, header},
4	response::{IntoResponse, Response},
5	};
6	use serde_json::json;
7
8	use super::ctx::Ctx;
9	use crate::{headers::ACCEPT_PATCH, problem::Problem};
10
11	const THERAPY: &str = "Your options are listed in the Allow header. There are more of them than you think. You could also try being honest. It is not in the Allow header because it is not a method.";
12
13	pub type Handler<T> = fn(&mut T, &Ctx) -> Response;
14
15	/// A predicate for when a method is available, and the refusal when it is not.
16	type Guard<T> = (fn(&T) -> bool, &'static str);
17
18	fn never<T>(_: &T) -> bool {
19	false
20	}
21
22	fn unanswered<T>(_: &mut T, _: &Ctx) -> Response {
23	StatusCode::METHOD_NOT_ALLOWED.into_response()
24	}
25
26	pub struct Verb<T: 'static> {
27	method: &'static str,
28	handle: Handler<T>,
29	guard: Option<Guard<T>>,
30	}
31
32	impl<T> Verb<T> {
33	pub const fn new(method: &'static str, handle: Handler<T>) -> Self {
34	Self {
35	method,
36	handle,
37	guard: None,
38	}
39	}
40
41	/// A method named only to be refused, so that its `405` can say why.
42	pub const fn refused(method: &'static str, refusal: &'static str) -> Self {
43	Self {
44	method,
45	handle: unanswered::<T>,
46	guard: Some((never::<T>, refusal)),
47	}
48	}
49
50	pub const fn only_when(self, available: fn(&T) -> bool, refusal: &'static str) -> Self {
51	Self {
52	guard: Some((available, refusal)),
53	..self
54	}
55	}
56
57	fn available(&self, target: &T) -> bool {
58	self.guard.is_none_or(\|(available, _)\| available(target))
59	}
60	}
61
62	/// The methods a resource supports. `Allow`, `OPTIONS` and `405` are all derived from this list.
63	pub struct Resource<T: 'static> {
64	verbs: &'static [Verb<T>],
65	accept_patch: bool,
66	}
67
68	impl<T> Resource<T> {
69	pub const fn new(verbs: &'static [Verb<T>]) -> Self {
70	Self {
71	verbs,
72	accept_patch: false,
73	}
74	}
75
76	pub const fn patchable(verbs: &'static [Verb<T>]) -> Self {
77	Self {
78	verbs,
79	accept_patch: true,
80	}
81	}
82
83	pub fn allow(&self, target: &T) -> String {
84	Self::listed(self.verbs.iter().filter(\|verb\| verb.available(target)))
85	}
86
87	fn listed<'a>(verbs: impl Iterator<Item = &'a Verb<T>>) -> String {
88	let mut methods = Vec::new();
89	for verb in verbs {
90	methods.push(verb.method);
91	if verb.method == "GET" {
92	methods.push("HEAD");
93	}
94	}
95	methods.push("OPTIONS");
96	methods.join(", ")
97	}
98
99	pub fn dispatch(&self, target: &mut T, ctx: &Ctx) -> Response {
100	let requested = ctx.method().as_str();
101	let lookup = if requested == "HEAD" {
102	"GET"
103	} else {
104	requested
105	};
106	match self.verbs.iter().find(\|verb\| verb.method == lookup) {
107	Some(verb) if verb.available(target) => (verb.handle)(target, ctx),
108	Some(verb) => {
109	let refusal = verb.guard.map_or("", \|(_, refusal)\| refusal);
110	method_not_allowed(refusal.to_owned(), &self.allow(target))
111	}
112	None if requested == "OPTIONS" => options(&self.allow(target), self.accept_patch),
113	None => unsupported(ctx.method(), &self.allow(target)),
114	}
115	}
116	}
117
118	fn method_not_allowed(detail: String, allow: &str) -> Response {
119	Problem::new(StatusCode::METHOD_NOT_ALLOWED, "method-not-allowed", detail)
120	.header(header::ALLOW, allow)
121	.into_response()
122	}
123
124	pub fn unsupported(method: &Method, allow: &str) -> Response {
125	let name = method.as_str();
126	match name {
127	"CONNECT" => StatusCode::NOT_IMPLEMENTED.into_response(),
128	"BREW" => Problem::new(
129	StatusCode::IM_A_TEAPOT,
130	"brew",
131	"The server is a teapot. RFC 2324 is clear on this. It is not yet short and stout.",
132	)
133	.into_response(),
134	"GET" \| "HEAD" \| "POST" \| "PUT" \| "PATCH" \| "DELETE" \| "OPTIONS" \| "TRACE" \| "JELQ"
135	\| "HOLD" => method_not_allowed(format!("{method} is not supported here."), allow),
136	_ if name.eq_ignore_ascii_case("jelq") => Problem::new(
137	StatusCode::NOT_IMPLEMENTED,
138	"not-implemented",
139	format!(
140	"The server does not implement {method}. Methods are case-sensitive. JELQ is shouted for a reason."
141	),
142	)
143	.into_response(),
144	_ => Problem::new(
145	StatusCode::NOT_IMPLEMENTED,
146	"not-implemented",
147	format!("The server does not implement {method}."),
148	)
149	.into_response(),
150	}
151	}
152
153	fn options(allow: &str, accept_patch: bool) -> Response {
154	let mut response = (
155	StatusCode::OK,
156	[(header::ALLOW, allow)],
157	Json(json!({ "detail": THERAPY })),
158	)
159	.into_response();
160	if accept_patch {
161	response.headers_mut().insert(
162	ACCEPT_PATCH,
163	HeaderValue::from_static("application/json-patch+json"),
164	);
165	}
166	response
167	}