3 files changed, 242 insertions, 0 deletions
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..ad27759
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,206 @@
+#[macro_use]
+extern crate diesel;
+
+use actix_web::{middleware, web, HttpResponse, HttpServer, Responder};
+use chrono::{Duration, Utc};
+use diesel::Connection;
+use diesel::prelude::*;
+use diesel::sqlite::SqliteConnection;
+use hmac::{Hmac, Mac};
+use serde::{Deserialize, Serialize};
+use sha2::Sha256;
+use std::collections::BTreeMap;
+use std::io;
+use std::sync::Mutex;
+
+mod models;
+mod schema;
+
+use self::models::*;
+
+/// Application context to be available on every request.
+struct Context {
+    db: Mutex<SqliteConnection>,
+    secret_key: Vec<u8>,
+}
+
+/// Time series of datapoints for a device.
+#[derive(Serialize)]
+struct DeviceData {
+    device: Device,
+    data: Vec<Datapoint>,
+}
+
+/// Data for a series of devices.
+#[derive(Serialize)]
+struct DataResponse {
+    devices: Vec<DeviceData>,
+}
+
+/// Data for a series of devices.
+#[derive(Serialize, Deserialize)]
+struct PutDataRequest {
+    device_id: String,
+    value: f64,
+    battery_value: f64,
+    signature: String,
+}
+
+impl DeviceData {
+    pub fn new(device: Device) -> Self {
+        DeviceData {
+            device,
+            data: Vec::new(),
+        }
+    }
+
+    pub fn add_datapoint(&mut self, datapoint: Datapoint) {
+        self.data.push(datapoint);
+    }
+}
+
+impl DataResponse {
+    pub fn new() -> Self {
+        DataResponse {
+            devices: Vec::new(),
+        }
+    }
+
+    pub fn add_device(&mut self, device_data: DeviceData) {
+        self.devices.push(device_data);
+    }
+}
+
+impl PutDataRequest {
+    pub fn validate_signature(&self, secret_key: &[u8]) -> bool {
+        let data = format!(
+            "battery_value={}&device_id={}&value={}",
+            self.battery_value,
+            urlencoding::encode(&self.device_id),
+            self.value
+        );
+
+        let signature = match hex::decode(&self.signature) {
+            Ok(signature) => signature,
+            Err(_) => {
+                log::info!(
+                    "Request has a malformed hex signature '{}'",
+                    &self.signature
+                );
+                return false;
+            }
+        };
+
+        let mut mac = match Hmac::<Sha256>::new_from_slice(secret_key) {
+            Ok(mac) => mac,
+            Err(e) => {
+                log::error!("Bad secret key configured: {}", e);
+                return false;
+            }
+        };
+
+        mac.update(data.as_bytes());
+        mac.verify_slice(&signature).is_ok()
+    }
+}
+
+async fn get_data(ctx: web::Data<Context>) -> impl Responder {
+    use self::schema::data::dsl::*;
+    use self::schema::devices::dsl::*;
+
+    let mut db = ctx.db.lock().unwrap();
+
+    let device_records = devices
+        .load::<Device>(&mut *db)
+        .expect("Error loading data");
+    let mut devicemap = BTreeMap::new();
+    device_records.into_iter().for_each(|record| {
+        devicemap.insert(record.device_id.to_string(), DeviceData::new(record));
+    });
+
+    let start_time = Utc::now() - Duration::days(30);
+    let data_records = data
+        .filter(timestamp.ge(start_time.naive_utc()))
+        .load::<Datapoint>(&mut *db)
+        .expect("Error loading data");
+
+    for datapoint in data_records {
+        devicemap
+            .get_mut(&datapoint.device_id)
+            .expect("Missing device in database!")
+            .add_datapoint(datapoint);
+    }
+
+    let mut response = DataResponse::new();
+    devicemap
+        .into_iter()
+        .for_each(|(_k, v)| response.add_device(v));
+
+    HttpResponse::Ok().json(response)
+}
+
+async fn put_data(req: web::Form<PutDataRequest>, ctx: web::Data<Context>) -> impl Responder {
+    use self::schema::data;
+    use self::schema::devices;
+
+    if !req.validate_signature(&ctx.secret_key) {
+        return HttpResponse::BadRequest().body("{error:\"Invalid signature\"}");
+    }
+
+    let mut db = ctx.db.lock().unwrap();
+
+    // Add the device record, if needed...
+    let device_record = Device {
+        device_id: req.device_id.to_string(),
+        name: "A beautiful flower".to_string(),
+    };
+    diesel::insert_into(devices::table)
+        .values(&device_record)
+        .on_conflict_do_nothing()
+        .execute(&mut *db)
+        .expect("Insert device record");
+
+    // Record the datapoint
+    let datapoint = Datapoint {
+        device_id: req.device_id.to_string(),
+        timestamp: Utc::now().naive_utc(),
+        value: req.value,
+    };
+    diesel::insert_into(data::table)
+        .values(&datapoint)
+        .execute(&mut *db)
+        .expect("Insert datapoint record");
+
+    HttpResponse::Created().finish()
+}
+
+fn open_database(db_filename: &str) -> io::Result<SqliteConnection> {
+    SqliteConnection::establish(db_filename).map_err(|e| io::Error::new(io::ErrorKind::Other, e))
+}
+
+#[actix_rt::main]
+async fn main() -> io::Result<()> {
+    dotenv::dotenv().ok();
+    env_logger::init();
+
+    let bind = std::env::var("BIND").unwrap_or_else(|_| "127.0.0.1:8180".to_string());
+    let db_path = std::env::var("DATABASE_URL").expect("Missing DATABASE env variable");
+    let secret_key = std::env::var("SECRET_KEY").expect("Missing SECRET_KEY env variable");
+
+    let ctx = web::Data::new(Context {
+        db: Mutex::new(open_database(&db_path)?),
+        secret_key: secret_key.into_bytes(),
+    });
+
+    HttpServer::new(move || {
+        actix_web::App::new()
+            .wrap(middleware::Logger::default())
+            .app_data(ctx.clone())
+            .route("/data", web::get().to(get_data))
+            .route("/data", web::put().to(put_data))
+    })
+    .bind(bind)
+    .unwrap()
+    .run()
+    .await
+}
diff --git a/src/models.rs b/src/models.rs
new file mode 100644
index 0000000..d8796d0
--- /dev/null
+++ b/src/models.rs
@@ -0,0 +1,18 @@
+use chrono::NaiveDateTime;
+use serde::Serialize;
+
+use super::schema::*;
+
+#[derive(Serialize, Queryable, Insertable)]
+pub struct Device {
+    pub device_id: String,
+    pub name: String,
+}
+
+#[derive(Serialize, Queryable, Insertable)]
+#[diesel(table_name = data)]
+pub struct Datapoint {
+    pub device_id: String,
+    pub timestamp: NaiveDateTime,
+    pub value: f64,
+}
diff --git a/src/schema.rs b/src/schema.rs
new file mode 100644
index 0000000..04e88dc
--- /dev/null
+++ b/src/schema.rs
@@ -0,0 +1,18 @@
+table! {
+    data (device_id, timestamp) {
+        device_id -> Text,
+        timestamp -> Timestamp,
+        value -> Double,
+    }
+}
+
+table! {
+    devices (device_id) {
+        device_id -> Text,
+        name -> Text,
+    }
+}
+
+joinable!(data -> devices (device_id));
+
+allow_tables_to_appear_in_same_query!(data, devices,);