package devices

import (
	"context"
	"database/sql"
	"fmt"
	"testing"
	"time"

	"github.com/wangjia/pangolin/server/internal/config"
	"github.com/wangjia/pangolin/server/internal/store"
)

// --------------------------------------------------------------------------
// SQLite fixture for migration 000025 (users.max_devices_override). No
// container needed — modernc.org/sqlite is pure Go — so these run in normal
// CI alongside run_sqlite_test.sh's data-layer tests.
// --------------------------------------------------------------------------

func openOverrideTestDB(t *testing.T) *sql.DB {
	t.Helper()
	cfg := &config.Config{Driver: "sqlite", DSN: ":memory:"}
	db, err := store.Open(cfg)
	if err != nil {
		t.Fatalf("store.Open: %v", err)
	}
	t.Cleanup(func() { db.Close() })
	if err := store.MigrateUp(db, "sqlite"); err != nil {
		t.Fatalf("MigrateUp: %v", err)
	}
	return db
}

// insertOverrideTestUser inserts an active user with an optional
// max_devices_override (NULL when override.Valid is false).
func insertOverrideTestUser(t *testing.T, db *sql.DB, email string, override sql.NullInt64) int64 {
	t.Helper()
	var (
		res sql.Result
		err error
	)
	if override.Valid {
		res, err = db.Exec(
			`INSERT INTO users (uuid, email, pw_hash, dp_uuid, status, max_devices_override)
			 VALUES (?, ?, 'x', ?, 'active', ?)`,
			"uuid-"+email, email, "dp-"+email, override.Int64)
	} else {
		res, err = db.Exec(
			`INSERT INTO users (uuid, email, pw_hash, dp_uuid, status)
			 VALUES (?, ?, 'x', ?, 'active')`,
			"uuid-"+email, email, "dp-"+email)
	}
	if err != nil {
		t.Fatalf("insert user %s: %v", email, err)
	}
	id, err := res.LastInsertId()
	if err != nil {
		t.Fatalf("last insert id: %v", err)
	}
	return id
}

// giveOverrideTestSubscription inserts an active subscription for userID on
// the given seeded plan code (free/pro/team, from migration 000007).
func giveOverrideTestSubscription(t *testing.T, db *sql.DB, userID int64, planCode, source string, expiresAt time.Time) {
	t.Helper()
	var planID int64
	if err := db.QueryRow(`SELECT id FROM plans WHERE code=?`, planCode).Scan(&planID); err != nil {
		t.Fatalf("plan lookup %s: %v", planCode, err)
	}
	if _, err := db.Exec(
		`INSERT INTO subscriptions (user_id, plan_id, expires_at, source) VALUES (?, ?, ?, ?)`,
		userID, planID, expiresAt.UTC(), source); err != nil {
		t.Fatalf("give subscription: %v", err)
	}
}

// insertOverrideTestDevice inserts an active (recently-seen) device row so it
// counts toward CountActiveDevices.
func insertOverrideTestDevice(t *testing.T, db *sql.DB, userID int64, uuidSuffix string) {
	t.Helper()
	if _, err := db.Exec(
		`INSERT INTO devices (uuid, user_id, name, platform, last_seen) VALUES (?, ?, ?, ?, ?)`,
		"dev-"+uuidSuffix, userID, "Device "+uuidSuffix, "ios", time.Now().UTC()); err != nil {
		t.Fatalf("insert device: %v", err)
	}
}

// --------------------------------------------------------------------------
// ResolvePlan: override applied at the single funnel (both the free fallback
// and the subscription path flow through it).
// --------------------------------------------------------------------------

// TestResolvePlan_FreeUserNoOverride: a free user with no override set gets
// the plan's default cap (free = 1, per migration 000007 seed).
func TestResolvePlan_FreeUserNoOverride(t *testing.T) {
	db := openOverrideTestDB(t)
	svc := NewService(NewStore(db), nil)
	userID := insertOverrideTestUser(t, db, "free-none@example.com", sql.NullInt64{})

	plan, apiErr := svc.ResolvePlan(context.Background(), userID)
	if apiErr != nil {
		t.Fatalf("ResolvePlan: %v", apiErr)
	}
	if plan.PlanCode != "free" {
		t.Errorf("PlanCode = %q, want free", plan.PlanCode)
	}
	if plan.MaxDevices != 1 {
		t.Errorf("MaxDevices = %d, want 1 (free plan default, no override)", plan.MaxDevices)
	}
}

// TestResolvePlan_FreeUserWithOverride: same free user, override=6 → the
// free-fallback path (GetFreePlan) must be overridden too.
func TestResolvePlan_FreeUserWithOverride(t *testing.T) {
	db := openOverrideTestDB(t)
	svc := NewService(NewStore(db), nil)
	userID := insertOverrideTestUser(t, db, "free-override@example.com", sql.NullInt64{Int64: 6, Valid: true})

	plan, apiErr := svc.ResolvePlan(context.Background(), userID)
	if apiErr != nil {
		t.Fatalf("ResolvePlan: %v", apiErr)
	}
	if plan.PlanCode != "free" {
		t.Errorf("PlanCode = %q, want free (override must not change plan identity)", plan.PlanCode)
	}
	if plan.MaxDevices != 6 {
		t.Errorf("MaxDevices = %d, want 6 (override)", plan.MaxDevices)
	}
}

// TestResolvePlan_ProSubscriptionOverrideWins: a pro-subscription user
// (plan default max_devices=3) with override=2 — the subscription path
// (resolveEffectivePlan's "best" branch) must also be overridden, even
// though the override is *smaller* than the plan's own cap.
func TestResolvePlan_ProSubscriptionOverrideWins(t *testing.T) {
	db := openOverrideTestDB(t)
	svc := NewService(NewStore(db), nil)
	userID := insertOverrideTestUser(t, db, "pro-override@example.com", sql.NullInt64{Int64: 2, Valid: true})
	giveOverrideTestSubscription(t, db, userID, "pro", "trial", time.Now().UTC().Add(24*time.Hour))

	plan, apiErr := svc.ResolvePlan(context.Background(), userID)
	if apiErr != nil {
		t.Fatalf("ResolvePlan: %v", apiErr)
	}
	if plan.PlanCode != "pro" {
		t.Errorf("PlanCode = %q, want pro", plan.PlanCode)
	}
	if plan.MaxDevices != 2 {
		t.Errorf("MaxDevices = %d, want 2 (override wins over pro plan's own cap of 3)", plan.MaxDevices)
	}
}

// TestResolvePlan_NullOrZeroOverrideDoesNotApply: NULL and 0 both mean
// "no override" — the plan-derived cap must stand.
func TestResolvePlan_NullOrZeroOverrideDoesNotApply(t *testing.T) {
	db := openOverrideTestDB(t)
	svc := NewService(NewStore(db), nil)

	nullUser := insertOverrideTestUser(t, db, "null-override@example.com", sql.NullInt64{})
	zeroUser := insertOverrideTestUser(t, db, "zero-override@example.com", sql.NullInt64{Int64: 0, Valid: true})

	for _, tc := range []struct {
		name   string
		userID int64
	}{
		{"NULL", nullUser},
		{"zero", zeroUser},
	} {
		t.Run(tc.name, func(t *testing.T) {
			plan, apiErr := svc.ResolvePlan(context.Background(), tc.userID)
			if apiErr != nil {
				t.Fatalf("ResolvePlan: %v", apiErr)
			}
			if plan.MaxDevices != 1 {
				t.Errorf("MaxDevices = %d, want 1 (no override should apply)", plan.MaxDevices)
			}
		})
	}
}

// --------------------------------------------------------------------------
// CheckDeviceLimit: behavioral assertion using the existing rig (it calls
// ResolvePlan internally) — override raises the effective cap so a device
// count that would be rejected under the free default is no longer flagged.
// --------------------------------------------------------------------------

func TestCheckDeviceLimit_OverrideAllowsMoreDevicesThanFreeCap(t *testing.T) {
	db := openOverrideTestDB(t)
	svc := NewService(NewStore(db), nil)
	userID := insertOverrideTestUser(t, db, "backstop@example.com", sql.NullInt64{Int64: 6, Valid: true})

	// Free plan cap is 1; without the override 3 active devices would be
	// rejected (Over=true). The override raises the cap to 6.
	for i := 0; i < 3; i++ {
		insertOverrideTestDevice(t, db, userID, fmt.Sprintf("%d", i))
	}

	status, apiErr := svc.CheckDeviceLimit(context.Background(), userID)
	if apiErr != nil {
		t.Fatalf("CheckDeviceLimit: %v", apiErr)
	}
	if status.MaxDevices != 6 {
		t.Errorf("MaxDevices = %d, want 6", status.MaxDevices)
	}
	if status.Over {
		t.Errorf("Over = true, want false (override=6 covers 3 active devices; free default of 1 would reject them)")
	}
}