129 lines
3.2 KiB
Rust
129 lines
3.2 KiB
Rust
#![feature(proc_macro_hygiene, decl_macro)]
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extern crate serde;
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extern crate serde_json;
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#[macro_use]
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extern crate rocket;
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extern crate rocket_contrib;
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use rocket::response::Redirect;
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use rocket::{Rocket, State};
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use rocket_contrib::serve::StaticFiles;
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use rocket_contrib::templates::Template;
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use rand::distributions::Uniform;
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use rand::Rng;
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use chgk_ledb_lib::db;
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use chgk_ledb_lib::questions::Question;
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const DB_FILENAME: &str = "db.dat";
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trait ErrorEmpty {
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type Output;
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fn err_empty(self) -> Result<Self::Output, ()>;
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}
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impl<T, E> ErrorEmpty for Result<T, E> {
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type Output = T;
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fn err_empty(self) -> Result<Self::Output, ()> {
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self.map_err(|_| ())
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}
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}
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struct AppState{
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database_distribution: Uniform<usize>,
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}
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fn open_db() -> db::Reader<Question> {
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db::Reader::new(DB_FILENAME, 2048).expect("new db reader")
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}
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fn get_database_distribution() -> Uniform<usize> {
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let last_id = open_db().len();
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rand::distributions::Uniform::new_inclusive(1usize, last_id)
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}
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fn random_question_id(database_distribution: &Uniform<usize>) -> usize {
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let mut rng = rand::thread_rng();
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rng.sample(database_distribution)
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}
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fn get_question(id: usize) -> Result<Question, ()> {
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open_db().get(id - 1).err_empty()
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}
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fn show_question_details(template_name: &'static str, data: &AppState, id: usize) -> Template {
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match get_question(id) {
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Ok(question) => {
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let mut context = serde_json::to_value(question).expect("question serialize");
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if context.is_object() {
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let next_id = random_question_id(&data.database_distribution);
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context["next"] = serde_json::to_value(next_id).expect("question id serialize");
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}
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Template::render(template_name, &context)
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}
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Err(_) => {
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use std::collections::HashMap;
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let context: HashMap<String, String> = HashMap::new();
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Template::render("404", &context)
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}
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}
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}
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#[get("/q/<id>")]
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fn show_question(data: State<AppState>, id: usize) -> Template {
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show_question_details("question", data.inner(), id)
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}
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#[get("/q/<id>/a")]
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fn show_answer(data: State<AppState>, id: usize) -> Template {
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show_question_details("answer", data.inner(), id)
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}
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#[get("/q/0")]
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fn question0() -> Redirect {
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Redirect::to("/")
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}
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#[get("/q/0/a")]
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fn answer0() -> Redirect {
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Redirect::to("/")
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}
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#[get("/")]
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fn index(data: State<AppState>) -> Redirect {
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let id = random_question_id(&data.database_distribution);
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Redirect::temporary(format!("/q/{}", id))
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}
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#[catch(404)]
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fn not_found(_req: &rocket::Request) -> Template {
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use std::collections::HashMap;
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let context: HashMap<String, String> = HashMap::new();
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Template::render("404", &context)
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}
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fn rocket() -> Rocket {
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let state = AppState {
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database_distribution: get_database_distribution(),
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};
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rocket::ignite()
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.manage(state)
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.register(catchers![not_found])
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.mount(
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"/",
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routes![index, show_question, show_answer, question0, answer0],
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)
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.mount("/q", routes![index])
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.mount("/q/static", StaticFiles::from("static/"))
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.attach(Template::fairing())
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}
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fn main() {
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rocket().launch();
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}
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