Working on rust backend

backend/.env

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+RUST_LOG=backend=info,actix=info,diesel_migrations=info
+DATABASE_URL=postgres://postgres:password@localhost/notes_api
+HOST=127.0.0.1
+PORT=5000

backend/Cargo.toml

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+[package]
+name = "aviation-weather-backend"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+actix-web = "3.0"
+actix-rt = "1.0"
+chrono = { version = "0.4", features = ["serde"] }
+dotenv = "0.15.0"
+diesel = { version = "1.4", features = ["postgres", "r2d2", "uuid", "chrono"] }
+diesel_migrations = "1.4"
+env_logger = "0.10.0"
+lazy_static = "1.4"
+listenfd = "0.3"
+quick-xml = { version = "0.30.0", features = ["serialize"] }
+r2d2 = "0.8"
+reqwest = "0.11.19"
+serde = {version = "1.0.185", features = ["derive"]}
+serde_json = "1.0"
+tokio = { version = "1.32.0", features = ["macros", "rt"] }
+uuid = { version = "0.6", features = ["serde", "v4"] }

backend/diesel.toml

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+# For documentation on how to configure this file,
+# see diesel.rs/guides/configuring-diesel-cli
+
+[print_schema]
+file = "src/schema.rs"

backend/src/airports/mod.rs

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+mod model;
+mod routes;
+
+pub use model::*;
+pub use routes::init_routes;

backend/src/airports/model.rs

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+use crate::db;
+use crate::error_handler::CustomError;
+use crate::schema::airports;
+use diesel::prelude::*;
+use serde::{Deserialize, Serialize};
+
+#[derive(Serialize, Deserialize, AsChangeset, Insertable)]
+#[table_name = "airports"]
+pub struct Airport {
+  pub name: String,
+  pub icao: String,
+  pub latitude: f32,
+  pub longitude: f32,
+}
+
+#[derive(Serialize, Deserialize, Queryable)]
+pub struct Airports {
+  pub id: i32,
+  pub name: String,
+  pub icao: String,
+  pub latitude: f32,
+  pub longitude: f32,
+}
+
+impl Airports {
+  pub fn find_all() -> Result<Vec<Self>, CustomError> {
+    let conn = db::connection()?;
+    let airports = airports::table.load::<Airports>(&conn)?;
+    Ok(airports)
+  }
+}

backend/src/airports/routes.rs

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+use crate::airports::{Airport, Airports};
+use crate::error_handler::CustomError;
+use actix_web::{delete, get, post, put, web, HttpResponse};
+use serde_json::json;
+
+#[get("/airports")]
+async fn find_all() -> Result<HttpResponse, CustomError> {
+  let airports = web::block(|| Airports::find_all()).await.unwrap();
+    Ok(HttpResponse::Ok().json(airports))
+}
+
+pub fn init_routes(config: &mut web::ServiceConfig) {
+  config.service(find_all);
+}

backend/src/db.rs

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+use crate::error_handler::CustomError;
+use diesel::pg::PgConnection;
+use diesel::r2d2::ConnectionManager;
+use lazy_static::lazy_static;
+use r2d2;
+use std::env;
+
+type Pool = r2d2::Pool<ConnectionManager<PgConnection>>;
+pub type DbConnection = r2d2::PooledConnection<ConnectionManager<PgConnection>>;
+
+embed_migrations!();
+
+lazy_static! {
+    static ref POOL: Pool = {
+        let db_url = env::var("DATABASE_URL").expect("Database url not set");
+        let manager = ConnectionManager::<PgConnection>::new(db_url);
+        Pool::new(manager).expect("Failed to create db pool")
+    };
+}
+
+pub fn init() {
+    lazy_static::initialize(&POOL);
+    let conn = connection().expect("Failed to get db connection");
+    embedded_migrations::run(&conn).unwrap();
+}
+
+pub fn connection() -> Result<DbConnection, CustomError> {
+    POOL.get()
+        .map_err(|e| CustomError::new(500, format!("Failed getting db connection: {}", e)))
+}

backend/src/error_handler.rs

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+use actix_web::http::StatusCode;
+use actix_web::{HttpResponse, ResponseError};
+use diesel::result::Error as DieselError;
+use serde::Deserialize;
+use serde_json::json;
+use std::fmt;
+
+#[derive(Debug, Deserialize)]
+pub struct CustomError {
+    pub error_status_code: u16,
+    pub error_message: String,
+}
+
+impl CustomError {
+    pub fn new(error_status_code: u16, error_message: String) -> CustomError {
+        CustomError {
+            error_status_code,
+            error_message,
+        }
+    }
+}
+
+impl fmt::Display for CustomError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str(self.error_message.as_str())
+    }
+}
+
+impl From<DieselError> for CustomError {
+    fn from(error: DieselError) -> CustomError {
+        match error {
+            DieselError::DatabaseError(_, err) => CustomError::new(409, err.message().to_string()),
+            DieselError::NotFound => {
+                CustomError::new(404, "The employee record not found".to_string())
+            }
+            err => CustomError::new(500, format!("Unknown Diesel error: {}", err)),
+        }
+    }
+}
+
+impl ResponseError for CustomError {
+    fn error_response(&self) -> HttpResponse {
+        let status_code = match StatusCode::from_u16(self.error_status_code) {
+            Ok(status_code) => status_code,
+            Err(_) => StatusCode::INTERNAL_SERVER_ERROR,
+        };
+
+        let error_message = match status_code.as_u16() < 500 {
+            true => self.error_message.clone(),
+            false => "Internal server error".to_string(),
+        };
+
+        HttpResponse::build(status_code).json(json!({ "message": error_message }))
+    }
+}

backend/src/lib.rs.bk

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+use std::error::Error;
+use std::fmt;
+use log::warn;
+use std::io::BufRead;
+use quick_xml::{Reader, events::{Event, BytesStart}, Writer, de::Deserializer};
+use serde::Deserialize;
+
+pub struct Airport {
+    pub name: String,
+    pub icao: String
+}
+
+impl Airport {
+    pub fn new(name: String, icao: String) -> Airport {
+        Airport { name, icao }
+    }
+}
+
+#[derive(Debug)]
+pub struct WeatherError(pub String);
+
+impl fmt::Display for WeatherError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+impl Error for WeatherError {}
+
+#[derive(Deserialize, Debug)]
+pub struct Metar {
+    pub raw_text: String,
+    pub station_id: String,
+    pub observation_time: String,
+    pub latitude: f32,
+    pub longitude: f32,
+    pub temp_c: f32,
+    pub dewpoint_c: f32,
+    pub wind_dir_degrees: i32,
+    pub wind_speed_kt: i32,
+    pub visibility_statute_mi: String,
+    pub altim_in_hg: f32,
+    pub sea_level_pressure_mb: Option<f32>,
+    pub quality_control_flags: Option<QualityControlFlags>,
+    pub wx_string: Option<String>,
+    // pub sky_con dition: Option<Vec<String>>, // TODO work on attributes
+    pub flight_category: String,
+    pub three_hr_pressure_tendency_mb: Option<f32>,
+    pub metar_type: String,
+    #[serde(rename = "maxT_c")]
+    pub max_t_c: Option<f32>,
+    #[serde(rename = "minT_c")]
+    pub min_t_c: Option<f32>,
+    pub precip_in: Option<f32>,
+    pub elevation_m: i32
+}
+
+#[derive(Deserialize, Debug)]
+pub struct QualityControlFlags {
+    pub auto: Option<bool>,
+    pub auto_station: Option<bool>
+}
+
+impl Metar {
+    pub fn parse(input: String) -> Result<Vec<Metar>, WeatherError> {
+        if input.is_empty() {
+            return Err(WeatherError("Input is empty".to_string()))
+        }
+
+        let mut reader = Reader::from_str(&input);
+        let mut buf = Vec::new();
+        let mut junk_buf: Vec<u8> = Vec::new();
+
+        loop {
+            match reader.read_event_into(&mut buf) {
+                Err(e) => panic!("Error at position: {}: {:?}", reader.buffer_position(), e),
+                Ok(Event::Eof) => break,
+                Ok(Event::Start(e)) => {
+                    match e.name().as_ref() {
+                        b"METAR" => {
+                            let metar_bytes = Metar::read_to_end_into_buffer(&mut reader, &e, &mut junk_buf).unwrap();
+                            let str = std::str::from_utf8(&metar_bytes).unwrap();
+                            let mut deserializer = Deserializer::from_str(str);
+                            let metar = Metar::deserialize(&mut deserializer).unwrap();
+                            println!("{:#?}", metar);
+                        },
+                        _ => ()
+                    }
+                },
+                _ => ()
+            }
+        }
+
+        return Ok(vec![])
+    }
+
+    // https://capnfabs.net/posts/parsing-huge-xml-quickxml-rust-serde/
+    pub fn read_to_end_into_buffer<R: BufRead>(reader: &mut Reader<R>, start_tag: &BytesStart, junk_buf: &mut Vec<u8>) -> Result<Vec<u8>, quick_xml::Error> {
+        let mut depth = 0;
+        let mut output_buf: Vec<u8> = Vec::new();
+        let mut w = Writer::new(&mut output_buf);
+        let tag_name = start_tag.name();
+        w.write_event(Event::Start(start_tag.clone()))?;
+        loop {
+            junk_buf.clear();
+            let event = reader.read_event_into(junk_buf)?;
+            w.write_event(&event)?;
+      
+            match event {
+                Event::Start(e) if e.name() == tag_name => depth += 1,
+                Event::End(e) if e.name() == tag_name => {
+                    if depth == 0 {
+                        return Ok(output_buf);
+                    }
+                    depth -= 1;
+                }
+                Event::Eof => {
+                    panic!("EOF")
+                }
+                _ => {}
+            }
+        }
+    }
+}
+
+pub struct Weather {
+    pub base_url: String
+}
+
+impl Weather {
+    pub async fn metar(&mut self, airports: Vec<Airport>) -> Vec<Metar> {
+        let mut station_icaos: Vec<&str> = vec![];
+        for station in airports.iter() {
+            station_icaos.push(&station.icao);
+        }
+        let station_string = station_icaos.join(",");
+        let url = format!("{}/metar.php?ids={}&format=xml", self.base_url, station_string);
+        
+        let metars: Vec<Metar> = match reqwest::get(url).await {
+            Ok(r) => match r.text().await {
+                Ok(r) => {
+                    match Metar::parse(r) {
+                        Ok(m) => m,
+                        Err(err) => {
+                            warn!("{}", err);
+                            vec![]
+                        }
+                    }
+                },
+                Err(err) => {
+                    warn!("Unable to parse METAR request: {}", err);
+                    vec![]
+                }
+            },
+            Err(err) => {
+                warn!("Unable to get METAR request: {}", err);
+                vec![]
+            }
+        };
+        return metars;
+    }
+}

backend/src/main.rs

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+#[macro_use]
+extern crate diesel;
+#[macro_use]
+extern crate diesel_migrations;
+
+use actix_web::{App, HttpServer};
+use dotenv::dotenv;
+use listenfd::ListenFd;
+use std::env;
+
+mod airports;
+mod db;
+mod error_handler;
+mod schema;
+
+#[actix_rt::main]
+async fn main() -> std::io::Result<()> {
+    dotenv().ok();
+    db::init();
+
+    let mut listenfd = ListenFd::from_env();
+    let mut server = HttpServer::new(|| App::new().configure(airports::init_routes));
+
+    server = match listenfd.take_tcp_listener(0)? {
+        Some(listener) => server.listen(listener)?,
+        None => {
+            let host = env::var("HOST").expect("Please set host in .env");
+            let port = env::var("PORT").expect("Please set port in .env");
+            server.bind(format!("{}:{}", host, port))?
+        }
+    };
+    server.run().await
+}

backend/src/schema.rs

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+table! {
+  airports (id) {
+    id -> Int4,
+    name -> Varchar,
+    icao -> Varchar,
+    latitude: Int4,
+    longitude: Int4
+  }
+}