feat: add the student API under /_bm/api/v1

Dashboard, courses with counters, schedule, meetings, deadlines,
readings with per-user progress (mark and unmark) and paginated
published materials with tags and files, behind golem15.user's
jwt.auth. Responses are built field by field with Warsaw RFC 3339
timestamps; bad query parameters answer 422 in Laravel's shape.

controllers/api/dashboard.go

@@ -0,0 +1,88 @@
+package api
+
+import (
+	"net/http"
+
+	"git.golem15.com/jakub/sm-bm-plugin/models"
+	"gorm.io/gorm"
+)
+
+// dashboardJSON is the answer of /dashboard.
+type dashboardJSON struct {
+	NextSessions      []sessionJSON   `json:"next_sessions"`
+	UpcomingDeadlines []deadlineJSON  `json:"upcoming_deadlines"`
+	CurrentMeeting    *meetingJSON    `json:"current_meeting"`
+	NextMeeting       *meetingJSON    `json:"next_meeting"`
+	Readings          readingsSummary `json:"readings"`
+}
+
+// Dashboard answers GET /dashboard: the next class sessions (those not yet
+// over), the deadlines not yet due, the meeting under way today and the next
+// one, and the caller's reading progress.
+func (h *Handlers) Dashboard(w http.ResponseWriter, r *http.Request) {
+	userID, ok := h.caller(w, r)
+	if !ok {
+		return
+	}
+	db, ok := h.db(w, r)
+	if !ok {
+		return
+	}
+	now := h.now().UTC()
+	limit := h.dashboardLimit()
+	out := dashboardJSON{}
+
+	var sessions []models.ClassSession
+	if err := preloadSession(db).Where("ends_at > ?", now).Order("starts_at, id").Limit(limit).Find(&sessions).Error; err != nil {
+		writeOpaque500(w)
+		return
+	}
+	out.NextSessions = newSessionsJSON(sessions)
+
+	var deadlines []models.Deadline
+	if err := db.Preload("Course").Where("due_at >= ?", now).Order("due_at, id").Limit(limit).Find(&deadlines).Error; err != nil {
+		writeOpaque500(w)
+		return
+	}
+	out.UpcomingDeadlines = newDeadlinesJSON(deadlines)
+
+	day := today(h.now()).Format(models.DateLayout)
+	var err error
+	if out.CurrentMeeting, err = meetingWhere(db, "starts_on <= ? AND ends_on >= ?", day, day); err != nil {
+		writeOpaque500(w)
+		return
+	}
+	if out.NextMeeting, err = meetingWhere(db, "starts_on > ?", day); err != nil {
+		writeOpaque500(w)
+		return
+	}
+
+	err = db.Raw(`SELECT
+	COUNT(*) AS total,
+	COUNT(p.id) AS read,
+	COUNT(*) FILTER (WHERE r.is_required) AS required_total,
+	COUNT(p.id) FILTER (WHERE r.is_required) AS required_read
+FROM jz_bm_readings r
+LEFT JOIN jz_bm_reading_progress p ON p.reading_id = r.id AND p.user_id = ?`, userID).Scan(&out.Readings).Error
+	if err != nil {
+		writeOpaque500(w)
+		return
+	}
+	writeData(w, out)
+}
+
+// meetingWhere returns the first meeting by start date that matches the
+// condition, with its session count, or nil.
+func meetingWhere(db *gorm.DB, cond string, args ...any) (*meetingJSON, error) {
+	var m models.Meeting
+	res := db.Where(cond, args...).Order("starts_on, number").Limit(1).Find(&m)
+	if res.Error != nil || res.RowsAffected == 0 {
+		return nil, res.Error
+	}
+	var sessions int64
+	if err := db.Model(&models.ClassSession{}).Where("meeting_id = ?", m.ID).Count(&sessions).Error; err != nil {
+		return nil, err
+	}
+	out := newMeetingJSON(m, sessions)
+	return &out, nil
+}