package store_test

import (
	"context"
	"testing"
	"time"

	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/stretchr/testify/require"
)

// seedReportUser inserts a user + its identity mapping (the enumeration source
// ActiveWeeks reads). display_name is optional.
func seedReportUser(t *testing.T, p *pgxpool.Pool, userID, subject, name string) {
	t.Helper()
	ctx := context.Background()
	_, err := p.Exec(ctx,
		`INSERT INTO users (id, display_name) VALUES ($1, NULLIF($2, ''))`, userID, name)
	require.NoError(t, err)
	_, err = p.Exec(ctx,
		`INSERT INTO user_identities (dex_subject, user_id) VALUES ($1, $2)`, subject, userID)
	require.NoError(t, err)
}

// TestActiveWeeksCountsDistinctWeeksAcrossReadsAndActs is the gate-query proof.
// It seeds, with fixed timestamps in known ISO weeks:
//   - user A: reads in week of Jan 5 and Jan 12, acts in week of Jan 12 (dup) and
//     Jan 19 → the UNION across both tables collapses the shared week → 3 distinct.
//   - user B: a single read in the week of Jan 5 → 1 distinct (below the gate).
//
// It verifies the count is correct, dedups the cross-table shared week, and orders
// most-active first.
func TestActiveWeeksCountsDistinctWeeksAcrossReadsAndActs(t *testing.T) {
	ctx := context.Background()
	s := newStore(t)
	p := rawPool(t)
	resetDB(t, p) // TRUNCATE ... users CASCADE also clears user_identities

	seedReportUser(t, p, userA, "subject-a", "Ada")
	seedReportUser(t, p, userB, "subject-b", "")

	// Reads (login_events) — fixed dates in distinct ISO weeks.
	_, err := p.Exec(ctx,
		`INSERT INTO login_events (user_id, seen_at) VALUES
		   ($1, '2026-01-05T09:00:00Z'),
		   ($1, '2026-01-12T09:00:00Z'),
		   ($2, '2026-01-05T09:00:00Z')`, userA, userB)
	require.NoError(t, err)

	// Acts (summary_actions) — one in A's week-of-Jan-12 (shared with a read, must
	// dedup) and one in a new week (Jan 19).
	_, err = p.Exec(ctx,
		`INSERT INTO summary_actions (user_id, video_id, action, acted_at) VALUES
		   ($1, 'vid-1', 'watched', '2026-01-12T18:00:00Z'),
		   ($1, 'vid-2', 'saved',   '2026-01-19T18:00:00Z')`, userA)
	require.NoError(t, err)

	got, err := s.ActiveWeeks(ctx, time.Time{}) // zero since = no lower bound
	require.NoError(t, err)
	require.Len(t, got, 2, "both identity users must appear")

	require.Equal(t, userA, got[0].UserID, "most-active user first")
	require.Equal(t, "Ada", got[0].DisplayName)
	require.Equal(t, 3, got[0].ActiveWeeks, "3 distinct weeks across reads+acts, shared week deduped")

	require.Equal(t, userB, got[1].UserID)
	require.Equal(t, 1, got[1].ActiveWeeks, "single read = 1 distinct week (below gate)")
}

// TestActiveWeeksEmptyWhenNoUsers: no identities → no rows (not an error).
func TestActiveWeeksEmptyWhenNoUsers(t *testing.T) {
	ctx := context.Background()
	s := newStore(t)
	resetDB(t, rawPool(t))

	got, err := s.ActiveWeeks(ctx, time.Time{})
	require.NoError(t, err)
	require.Empty(t, got)
}

// TestActiveWeeksExcludesBeforeGateStart proves the baseline cutoff: activity
// before `since` does not count, so pre-launch noise (testing, the pilot's blocked
// period) is excluded from the Stage-0 return-usage gate (ADR-016).
func TestActiveWeeksExcludesBeforeGateStart(t *testing.T) {
	ctx := context.Background()
	s := newStore(t)
	p := rawPool(t)
	resetDB(t, p)

	seedReportUser(t, p, userA, "subject-a", "Ada")

	// One read well before the baseline, two reads in distinct weeks after it.
	_, err := p.Exec(ctx,
		`INSERT INTO login_events (user_id, seen_at) VALUES
		   ($1, '2026-05-01T09:00:00Z'),
		   ($1, '2026-06-12T09:00:00Z'),
		   ($1, '2026-06-19T09:00:00Z')`, userA)
	require.NoError(t, err)

	since := time.Date(2026, 6, 11, 0, 0, 0, 0, time.UTC)
	got, err := s.ActiveWeeks(ctx, since)
	require.NoError(t, err)
	require.Len(t, got, 1)
	require.Equal(t, 2, got[0].ActiveWeeks, "only the two post-baseline weeks count; the May read is excluded")
}