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);

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,
        }
    }

    /// Makes the method available only while `available` holds, refusing with `refusal` otherwise.
    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> {
    pub verbs: &'static [Verb<T>],
    pub accept_patch: bool,
}

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

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

    /// The methods with every guard assumed open, for resources that have none.
    pub fn allow_any(&self) -> String {
        Self::listed(self.verbs.iter())
    }

    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" => {
            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	pub struct Verb<T: 'static> {
19	method: &'static str,
20	handle: Handler<T>,
21	guard: Option<Guard<T>>,
22	}
23
24	impl<T> Verb<T> {
25	pub const fn new(method: &'static str, handle: Handler<T>) -> Self {
26	Self {
27	method,
28	handle,
29	guard: None,
30	}
31	}
32
33	/// Makes the method available only while `available` holds, refusing with `refusal` otherwise.
34	pub const fn only_when(self, available: fn(&T) -> bool, refusal: &'static str) -> Self {
35	Self {
36	guard: Some((available, refusal)),
37	..self
38	}
39	}
40
41	fn available(&self, target: &T) -> bool {
42	self.guard.is_none_or(\|(available, _)\| available(target))
43	}
44	}
45
46	/// The methods a resource supports. `Allow`, `OPTIONS` and `405` are all derived from this list.
47	pub struct Resource<T: 'static> {
48	pub verbs: &'static [Verb<T>],
49	pub accept_patch: bool,
50	}
51
52	impl<T> Resource<T> {
53	pub const fn new(verbs: &'static [Verb<T>]) -> Self {
54	Self {
55	verbs,
56	accept_patch: false,
57	}
58	}
59
60	pub fn allow(&self, target: &T) -> String {
61	Self::listed(self.verbs.iter().filter(\|verb\| verb.available(target)))
62	}
63
64	/// The methods with every guard assumed open, for resources that have none.
65	pub fn allow_any(&self) -> String {
66	Self::listed(self.verbs.iter())
67	}
68
69	fn listed<'a>(verbs: impl Iterator<Item = &'a Verb<T>>) -> String {
70	let mut methods = Vec::new();
71	for verb in verbs {
72	methods.push(verb.method);
73	if verb.method == "GET" {
74	methods.push("HEAD");
75	}
76	}
77	methods.push("OPTIONS");
78	methods.join(", ")
79	}
80
81	pub fn dispatch(&self, target: &mut T, ctx: &Ctx) -> Response {
82	let requested = ctx.method.as_str();
83	let lookup = if requested == "HEAD" {
84	"GET"
85	} else {
86	requested
87	};
88	match self.verbs.iter().find(\|verb\| verb.method == lookup) {
89	Some(verb) if verb.available(target) => (verb.handle)(target, ctx),
90	Some(verb) => {
91	let refusal = verb.guard.map_or("", \|(_, refusal)\| refusal);
92	method_not_allowed(refusal.to_owned(), &self.allow(target))
93	}
94	None if requested == "OPTIONS" => options(&self.allow(target), self.accept_patch),
95	None => unsupported(&ctx.method, &self.allow(target)),
96	}
97	}
98	}
99
100	fn method_not_allowed(detail: String, allow: &str) -> Response {
101	Problem::new(StatusCode::METHOD_NOT_ALLOWED, "method-not-allowed", detail)
102	.header(header::ALLOW, allow)
103	.into_response()
104	}
105
106	pub fn unsupported(method: &Method, allow: &str) -> Response {
107	let name = method.as_str();
108	match name {
109	"CONNECT" => StatusCode::NOT_IMPLEMENTED.into_response(),
110	"BREW" => Problem::new(
111	StatusCode::IM_A_TEAPOT,
112	"brew",
113	"The server is a teapot. RFC 2324 is clear on this. It is not yet short and stout.",
114	)
115	.into_response(),
116	"GET" \| "HEAD" \| "POST" \| "PUT" \| "PATCH" \| "DELETE" \| "OPTIONS" \| "TRACE" \| "JELQ" => {
117	method_not_allowed(format!("{method} is not supported here."), allow)
118	}
119	_ if name.eq_ignore_ascii_case("jelq") => Problem::new(
120	StatusCode::NOT_IMPLEMENTED,
121	"not-implemented",
122	format!(
123	"The server does not implement {method}. Methods are case-sensitive. JELQ is shouted for a reason."
124	),
125	)
126	.into_response(),
127	_ => Problem::new(
128	StatusCode::NOT_IMPLEMENTED,
129	"not-implemented",
130	format!("The server does not implement {method}."),
131	)
132	.into_response(),
133	}
134	}
135
136	fn options(allow: &str, accept_patch: bool) -> Response {
137	let mut response = (
138	StatusCode::OK,
139	[(header::ALLOW, allow)],
140	Json(json!({ "detail": THERAPY })),
141	)
142	.into_response();
143	if accept_patch {
144	response.headers_mut().insert(
145	ACCEPT_PATCH,
146	HeaderValue::from_static("application/json-patch+json"),
147	);
148	}
149	response
150	}