71 lines
2.4 KiB
Rust
71 lines
2.4 KiB
Rust
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//! Which storyline a visitor reads (see `content/variants.rs`): one
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//! index for the whole site, chosen at their first request and kept in
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//! a cookie for a year, so every page and every mail they get tells
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//! the same story. A site that tells one story sets no cookie.
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#![cfg(feature = "ssr")]
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use axum::{
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extract::{Request, State},
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http::header::{COOKIE, SET_COOKIE},
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middleware::Next,
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response::Response,
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};
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pub const COOKIE_NAME: &str = "portal_storyline";
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#[derive(Clone, Copy, Debug, PartialEq, Eq)]
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pub struct Storyline(pub usize);
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/// The index in a request's cookies, if it names one this site tells.
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fn from_cookies(header: Option<&str>, arity: usize) -> Option<usize> {
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header?
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.split(';')
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.map(str::trim)
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.find_map(|kv| kv.strip_prefix(COOKIE_NAME).and_then(|rest| rest.strip_prefix('=')))
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.and_then(|v| v.trim().parse::<usize>().ok())
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.filter(|n| *n < arity)
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}
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/// Evenly, from nothing about the person.
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fn pick(arity: usize) -> usize {
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(uuid::Uuid::new_v4().as_u128() % arity.max(1) as u128) as usize
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}
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pub async fn assign(State(state): State<super::AppState>, mut req: Request, next: Next) -> Response {
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let arity = state.questions.load().arity();
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let held = from_cookies(req.headers().get(COOKIE).and_then(|v| v.to_str().ok()), arity);
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let n = held.unwrap_or_else(|| pick(arity));
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req.extensions_mut().insert(Storyline(n));
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let mut res = next.run(req).await;
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if held.is_none() && arity > 1 {
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if let Ok(value) = format!("{COOKIE_NAME}={n}; Path=/; Max-Age=31536000; SameSite=Lax").parse() {
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res.headers_mut().append(SET_COOKIE, value);
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}
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}
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res
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}
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/// The storyline of the request a server function is answering, or
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/// the first when there is none to ask (a call outside a request).
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pub async fn current() -> usize {
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leptos_axum::extract::<axum::Extension<Storyline>>()
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.await
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.map(|axum::Extension(Storyline(n))| n)
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.unwrap_or(0)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn a_cookie_names_a_storyline_the_site_tells() {
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assert_eq!(from_cookies(Some("a=b; portal_storyline=1; c=d"), 3), Some(1));
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assert_eq!(from_cookies(Some("portal_storyline=7"), 3), None);
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assert_eq!(from_cookies(Some("portal_storylines=1"), 3), None);
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assert_eq!(from_cookies(None, 3), None);
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assert!(pick(1) == 0);
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assert!((0..50).all(|_| pick(3) < 3));
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}
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}
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