feature: Schema, Migrations, Core CRUD, and Redis Threshold Cache

VigilCareClinicalAPI/Services/EncounterService.cs

@@ -0,0 +1,78 @@
+using Microsoft.EntityFrameworkCore;
+
+public class EncounterService : IEncounterService
+{
+     // Explicit transition matrix. Every allowed move is listed here.
+    // Any transition not in this dictionary is illegal and throws ConflictException.
+    private static readonly Dictionary<EncounterStatus, HashSet<EncounterStatus>> _allowedTransitions = new()
+    {
+        [EncounterStatus.Scheduled] = new() { EncounterStatus.Active, EncounterStatus.Cancelled },
+        [EncounterStatus.Active]    = new() { EncounterStatus.Discharged, EncounterStatus.Cancelled },
+        [EncounterStatus.Discharged] = new(),
+        [EncounterStatus.Cancelled]  = new(),
+    };
+
+    private readonly AppDbContext _db;
+
+    public EncounterService(AppDbContext db) => _db = db;
+
+    public async Task<Encounter> GetByIdAsync(Guid id)
+    {
+        var encounter = await _db.Encounters
+            .Include(e => e.Patient)
+            .Include(e => e.Observations.OrderByDescending(o => o.RecordedAt).Take(10))
+            .Include(e => e.Alerts.Where(a => a.Status == AlertStatus.Open))
+            .FirstOrDefaultAsync(e => e.Id == id);
+
+        if (encounter is null)
+            throw new NotFoundException("Encounter not found.", "ENCOUNTER_NOT_FOUND");
+
+        return encounter;
+    }
+
+    public async Task<EncounterStatusTransitionResult> TransitionStatusAsync(
+        Guid encounterId, EncounterStatus targetStatus)
+    {
+        var encounter = await _db.Encounters.FindAsync(encounterId);
+        if (encounter is null)
+            throw new NotFoundException("Encounter not found.", "ENCOUNTER_NOT_FOUND");
+
+        if (!_allowedTransitions[encounter.Status].Contains(targetStatus))
+            throw new ConflictException(
+                $"Transition to '{targetStatus}' is not permitted from the current status.",
+                "ILLEGAL_STATUS_TRANSITION");
+
+        encounter.Status = targetStatus;
+        if (targetStatus == EncounterStatus.Discharged)
+            encounter.DischargedAt = DateTimeOffset.UtcNow;
+
+        await _db.SaveChangesAsync();
+        return new EncounterStatusTransitionResult(encounterId, targetStatus);
+    }
+
+    public async Task<object> GetTimelineAsync(Guid encounterId)
+    {
+        var encounter = await _db.Encounters.FindAsync(encounterId);
+        if (encounter is null)
+            throw new NotFoundException("Encounter not found.", "ENCOUNTER_NOT_FOUND");
+
+        var observations = await _db.Observations
+            .Where(o => o.EncounterId == encounterId)
+            .OrderByDescending(o => o.RecordedAt)
+            .Select(o => new { type = "observation", timestamp = o.RecordedAt, o.ObservationCode, o.Value, o.Unit })
+            .ToListAsync();
+
+        var alerts = await _db.ClinicalAlerts
+            .Where(a => a.EncounterId == encounterId)
+            .OrderByDescending(a => a.TriggeredAt)
+            .Select(a => new { type = "alert", timestamp = a.TriggeredAt, a.AlertType, a.Severity, a.Status })
+            .ToListAsync();
+
+        var timeline = observations.Cast<object>()
+            .Concat(alerts.Cast<object>())
+            .OrderByDescending(x => (DateTimeOffset)((dynamic)x).timestamp)
+            .ToList();
+
+        return new { encounterId, events = timeline };
+    }
+}