Phase 8: history

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/db/repo.go

@@ -445,6 +445,81 @@ func (r *Repo) GetStatsForUser(userID int64, questionIDs []string) (map[string]*
 	return result, rows.Err()
 }
 
+// ── History ──────────────────────────────────────────────────────────────────
+
+// GetCorrectCountsForUser returns a map of test_id → correct-answer count for
+// all completed tests belonging to userID.
+func (r *Repo) GetCorrectCountsForUser(userID int64) (map[int64]int, error) {
+	rows, err := r.db.Query(`
+		SELECT ta.test_id, SUM(CASE WHEN ta.is_correct = 1 THEN 1 ELSE 0 END)
+		FROM test_answers ta
+		JOIN tests t ON ta.test_id = t.id
+		WHERE t.user_id = ? AND t.completed_at IS NOT NULL
+		GROUP BY ta.test_id`, userID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	result := make(map[int64]int)
+	for rows.Next() {
+		var testID int64
+		var correct int
+		if err := rows.Scan(&testID, &correct); err != nil {
+			return nil, err
+		}
+		result[testID] = correct
+	}
+	return result, rows.Err()
+}
+
+// GetAggregateStats returns total correct and total answered across all
+// completed tests for userID.
+func (r *Repo) GetAggregateStats(userID int64) (totalCorrect, totalAnswered int, err error) {
+	err = r.db.QueryRow(`
+		SELECT
+			COALESCE(SUM(CASE WHEN ta.is_correct = 1 THEN 1 ELSE 0 END), 0),
+			COALESCE(COUNT(ta.question_id), 0)
+		FROM test_answers ta
+		JOIN tests t ON ta.test_id = t.id
+		WHERE t.user_id = ? AND t.completed_at IS NOT NULL`, userID,
+	).Scan(&totalCorrect, &totalAnswered)
+	return
+}
+
+// WeakSpot is a question the user has answered incorrectly more than once.
+type WeakSpot struct {
+	QuestionID   string
+	QuestionText string
+	TimesWrong   int
+	TimesSeen    int
+}
+
+// GetWeakSpots returns up to 10 questions the user has gotten wrong more than
+// once, ordered by wrong-answer count descending.
+func (r *Repo) GetWeakSpots(userID int64) ([]*WeakSpot, error) {
+	rows, err := r.db.Query(`
+		SELECT uqs.question_id, q.text, uqs.times_seen,
+		       (uqs.times_seen - uqs.times_correct) AS times_wrong
+		FROM user_question_stats uqs
+		JOIN questions q ON uqs.question_id = q.id
+		WHERE uqs.user_id = ? AND (uqs.times_seen - uqs.times_correct) > 1
+		ORDER BY times_wrong DESC, uqs.times_seen DESC
+		LIMIT 10`, userID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var spots []*WeakSpot
+	for rows.Next() {
+		s := &WeakSpot{}
+		if err := rows.Scan(&s.QuestionID, &s.QuestionText, &s.TimesSeen, &s.TimesWrong); err != nil {
+			return nil, err
+		}
+		spots = append(spots, s)
+	}
+	return spots, rows.Err()
+}
+
 // ── Draft (import review) ────────────────────────────────────────────────────
 
 func newDraftID() string {

internal/handlers/history.go

@@ -0,0 +1,76 @@
+package handlers
+
+import (
+	"log/slog"
+	"net/http"
+
+	"qbank/internal/auth"
+	"qbank/internal/db"
+	"qbank/internal/models"
+)
+
+type HistoryHandler struct {
+	auth   *auth.Manager
+	repo   *db.Repo
+	render *Renderer
+}
+
+func NewHistoryHandler(a *auth.Manager, repo *db.Repo, r *Renderer) *HistoryHandler {
+	return &HistoryHandler{auth: a, repo: repo, render: r}
+}
+
+// TestHistoryItem pairs a test with its correct-answer count.
+type TestHistoryItem struct {
+	*models.Test
+	NCorrect int
+}
+
+func (h *HistoryHandler) Handle(w http.ResponseWriter, r *http.Request) {
+	user := auth.UserFromCtx(r.Context())
+
+	tests, err := h.repo.ListTestsForUser(user.ID)
+	if err != nil {
+		slog.Error("list tests for history", "err", err)
+		HTTPError(w, http.StatusInternalServerError)
+		return
+	}
+
+	correctCounts, err := h.repo.GetCorrectCountsForUser(user.ID)
+	if err != nil {
+		slog.Error("get correct counts", "err", err)
+		HTTPError(w, http.StatusInternalServerError)
+		return
+	}
+
+	items := make([]TestHistoryItem, 0, len(tests))
+	for _, t := range tests {
+		if !t.CompletedAt.Valid {
+			continue // skip in-progress tests
+		}
+		items = append(items, TestHistoryItem{
+			Test:     t,
+			NCorrect: correctCounts[t.ID],
+		})
+	}
+
+	totalCorrect, totalAnswered, err := h.repo.GetAggregateStats(user.ID)
+	if err != nil {
+		slog.Error("get aggregate stats", "err", err)
+		HTTPError(w, http.StatusInternalServerError)
+		return
+	}
+
+	weakSpots, err := h.repo.GetWeakSpots(user.ID)
+	if err != nil {
+		slog.Error("get weak spots", "err", err)
+		HTTPError(w, http.StatusInternalServerError)
+		return
+	}
+
+	data := BaseData(h.auth, r)
+	data["Items"] = items
+	data["TotalCorrect"] = totalCorrect
+	data["TotalAnswered"] = totalAnswered
+	data["WeakSpots"] = weakSpots
+	h.render.Render(w, http.StatusOK, "history", data)
+}