Add API for expected attendance counts (#47)

Author: illicitonion

src/bin/trainee-tracker.rs

@@ -111,6 +111,10 @@ async fn main() {
             "/api/attendance",
             get(trainee_tracker::endpoints::fetch_attendance),
         )
+        .route(
+            "/api/expected-attendance",
+            get(trainee_tracker::endpoints::expected_attendance),
+        )
         .layer(session_layer)
         .with_state(server_state);
 

src/course.rs

@@ -16,8 +16,7 @@ use crate::{
     sheets::SheetsClient,
 };
 use anyhow::Context;
-use chrono::{DateTime, NaiveDate, NaiveDateTime, NaiveTime, TimeZone, Utc};
-use chrono_tz::Tz;
+use chrono::{NaiveDate, Utc};
 use email_address::EmailAddress;
 use futures::future::join_all;
 use indexmap::{IndexMap, IndexSet};
@@ -800,14 +799,7 @@ fn get_trainee_module_attendance(
                     .collect::<Vec<chrono::NaiveDate>>();
                 let attendance = match dates.as_slice() {
                     [date] => {
-                        let start_time = DateTime::<Tz>::from_naive_utc_and_offset(
-                            NaiveDateTime::new(
-                                date.clone(),
-                                NaiveTime::from_hms_opt(10, 00, 00).expect("TODO"),
-                            ),
-                            region.timezone().offset_from_utc_date(date),
-                        )
-                        .to_utc();
+                        let start_time = region.class_start_time(date);
                         let attendance = module_attendance
                             .attendance
                             .get(sprint_index)

src/endpoints.rs

@@ -1,10 +1,13 @@
+use std::{collections::BTreeMap, ops::AddAssign};
+
 use ::octocrab::models::{Author, teams::RequestedTeam};
 use anyhow::Context;
 use axum::{
     Json,
     extract::{OriginalUri, Path, State},
     response::IntoResponse,
 };
+use chrono::Utc;
 use futures::future::join_all;
 use http::HeaderMap;
 use indexmap::IndexMap;
@@ -284,3 +287,47 @@ pub async fn fetch_attendance(
     }
     Ok(Json(registered_attendance))
 }
+
+#[derive(Serialize)]
+pub struct ExpectedAttendance {
+    course: String,
+    cohort: String,
+    region: crate::newtypes::Region,
+    expected_classes: usize,
+}
+
+pub async fn expected_attendance(
+    State(server_state): State<ServerState>,
+) -> Json<Vec<ExpectedAttendance>> {
+    let now = Utc::now();
+
+    let mut expected_attendance = Vec::new();
+    for (course, course_info) in server_state.config.courses {
+        for (cohort, schedule) in course_info.batches {
+            let mut region_to_expected_classes: BTreeMap<crate::newtypes::Region, usize> =
+                BTreeMap::new();
+            for (_module_name, sprints) in schedule.sprints {
+                for sprint in sprints {
+                    for (region, date) in sprint {
+                        let start_time = region.class_start_time(&date);
+                        if start_time < now {
+                            region_to_expected_classes
+                                .entry(region)
+                                .or_default()
+                                .add_assign(1);
+                        }
+                    }
+                }
+            }
+            for (region, expected_classes) in region_to_expected_classes {
+                expected_attendance.push(ExpectedAttendance {
+                    course: course.clone(),
+                    cohort: cohort.clone(),
+                    region,
+                    expected_classes,
+                })
+            }
+        }
+    }
+    Json(expected_attendance)
+}

src/newtypes.rs

@@ -1,6 +1,7 @@
 use std::{fmt::Display, str::FromStr};
 
 use case_insensitive_string::CaseInsensitiveString;
+use chrono::{DateTime, NaiveDate, NaiveDateTime, NaiveTime, TimeZone, Utc};
 use email_address::EmailAddress;
 use serde::{Deserialize, Serialize};
 
@@ -52,4 +53,16 @@ impl Region {
     pub fn as_str(&self) -> &str {
         self.0.as_str()
     }
+
+    pub fn class_start_time(&self, date: &NaiveDate) -> DateTime<Utc> {
+        let offset = self.timezone().offset_from_utc_date(date);
+        DateTime::<chrono_tz::Tz>::from_naive_utc_and_offset(
+            NaiveDateTime::new(
+                *date,
+                NaiveTime::from_hms_opt(10, 00, 00).expect("Known time failed to parse"),
+            ),
+            offset,
+        )
+        .to_utc()
+    }
 }