feat(db): add session repository with stats queries

Author: Bahaaio

db/models.go

@@ -17,3 +17,21 @@ type Session struct {
 	Duration  time.Duration `db:"duration"`
 	StartedAt time.Time     `db:"started_at"`
 }
+
+type AllTimeStats struct {
+	TotalSessions      int           `db:"total_sessions"`
+	TotalWorkDuration  time.Duration `db:"total_work_duration"`
+	TotalBreakDuration time.Duration `db:"total_break_duration"`
+}
+
+type DailyStat struct {
+	Date         string        `db:"day"`
+	WorkDuration time.Duration `db:"work_duration"`
+}
+
+type SessionType string
+
+const (
+	WorkSession  SessionType = "work"
+	BreakSession SessionType = "break"
+)

db/repository.go

@@ -0,0 +1,116 @@
+package db
+
+import (
+	"time"
+
+	"github.com/jmoiron/sqlx"
+)
+
+const DateFormat = "2006-01-02"
+
+type SessionRepo struct {
+	db *sqlx.DB
+}
+
+func NewSessionRepo(db *sqlx.DB) *SessionRepo {
+	return &SessionRepo{db: db}
+}
+
+// CreateSession inserts a new session record into the database.
+func (r *SessionRepo) CreateSession(startedAt time.Time, duration time.Duration, sessionType SessionType) error {
+	startedAtStr := startedAt.Format(time.RFC3339)
+
+	if _, err := r.db.Exec(
+		"insert into sessions (started_at, duration, type) values (?,?,?);",
+		startedAtStr,
+		duration,
+		sessionType,
+	); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// GetAllTimeStats retrieves aggregate statistics across all sessions.
+func (r *SessionRepo) GetAllTimeStats() (AllTimeStats, error) {
+	var totalStats AllTimeStats
+
+	// sqlite treats (type = 'work') as 1 or 0
+	if err := r.db.Get(
+		&totalStats,
+		`
+		SELECT
+			COUNT(*) AS total_sessions,
+			COALESCE(SUM(duration * (type = 'work')), 0)  AS total_work_duration,
+			COALESCE(SUM(duration * (type = 'break')), 0) AS total_break_duration
+		FROM sessions;
+		`,
+	); err != nil {
+		return AllTimeStats{}, err
+	}
+
+	return totalStats, nil
+}
+
+func (r *SessionRepo) GetWeeklyStats() ([]DailyStat, error) {
+	today := time.Now()
+	firstDay := today.AddDate(0, 0, -6)
+
+	return r.getDailyStats(firstDay, today)
+}
+
+func (r *SessionRepo) GetMonthlyStats() ([]DailyStat, error) {
+	today := time.Now()
+	firstDay := today.AddDate(0, 0, -29)
+
+	return r.getDailyStats(firstDay, today)
+}
+
+func (r *SessionRepo) getDailyStats(from, to time.Time) ([]DailyStat, error) {
+	fromStr := from.Format(DateFormat)
+	toStr := to.Format(DateFormat)
+
+	var stats []DailyStat
+
+	if err := r.db.Select(
+		&stats,
+		`
+		SELECT
+			date(started_at) AS day,
+			COALESCE(SUM(duration * (type = 'work')), 0) AS work_duration
+		FROM sessions
+		WHERE date(started_at) BETWEEN ? AND ?
+		GROUP BY day
+		ORDER BY day;
+		`,
+		fromStr, toStr,
+	); err != nil {
+		return nil, err
+	}
+
+	return r.normalizeStats(from, to, stats), nil
+}
+
+func (r *SessionRepo) normalizeStats(from, to time.Time, stats []DailyStat) []DailyStat {
+	m := make(map[string]DailyStat)
+
+	for _, stat := range stats {
+		m[stat.Date] = stat
+	}
+
+	var normalized []DailyStat
+	current := from
+	for !current.After(to) {
+		day := current.Format(DateFormat)
+
+		normalized = append(normalized, DailyStat{
+			Date:         day,
+			WorkDuration: m[day].WorkDuration,
+		})
+
+		current = current.AddDate(0, 0, 1) // next day
+	}
+
+	return normalized
+}