package billing

import (
	"context"
	"crypto/sha256"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"strings"
	"testing"
	"time"

	"aigw/internal/controlplane"
	"aigw/internal/domain"

	"github.com/stripe/stripe-go/v86"
	"github.com/stripe/stripe-go/v86/webhook"
)

func TestUsageCostUsesFixedPointAndRoundsOnce(t *testing.T) {
	usage := domain.Usage{InputTokens: 3, OutputTokens: 2, CacheReadInputTokens: 5}
	cost, err := usageCost(usage, 150_000, 600_000, 30_000, 0)
	if err != nil {
		t.Fatal(err)
	}
	// (3*150000 + 2*600000 + 5*30000) / 1e6 = 1.8 micros.
	if cost != 2 {
		t.Fatalf("cost = %d, want 2", cost)
	}
}

func TestReservationUsesExplicitOutputLimit(t *testing.T) {
	model := domain.Model{InputPriceMicrosPerMillion: 1_000_000, OutputPriceMicrosPerMillion: 1_000_000}
	body := []byte(`{"max_tokens":8192}`)
	cost, err := reservationCost(model, body, 4096)
	if err != nil {
		t.Fatal(err)
	}
	want := int64(len(body)) + 8192
	if cost != want {
		t.Fatalf("reservation = %d, want %d", cost, want)
	}
}

func TestMinorToMicrosSupportsCurrencyExponents(t *testing.T) {
	tests := []struct {
		currency string
		minor    int64
		want     int64
	}{{"usd", 123, 1_230_000}, {"jpy", 123, 123_000_000}, {"bhd", 123, 123_000}}
	for _, test := range tests {
		got, err := minorToMicros(test.currency, test.minor)
		if err != nil {
			t.Fatalf("%s: %v", test.currency, err)
		}
		if got != test.want {
			t.Fatalf("%s: got %d, want %d", test.currency, got, test.want)
		}
	}
}

func TestCollectibleChargePreservesOtherReservations(t *testing.T) {
	charged, err := collectibleCharge(100, 100, 80, 40)
	if err != nil {
		t.Fatal(err)
	}
	if charged != 60 {
		t.Fatalf("charged = %d, want 60", charged)
	}
	if remainingBalance, remainingHeld := int64(100)-charged, int64(80)-40; remainingBalance < remainingHeld {
		t.Fatalf("remaining balance %d does not cover held %d", remainingBalance, remainingHeld)
	}
}

func TestIntegrationIdentifierSuffixUsesLetters(t *testing.T) {
	value := randomLetters(8)
	if len(value) != 8 {
		t.Fatalf("length = %d", len(value))
	}
	for _, char := range value {
		if char < 'a' || char > 'z' {
			t.Fatalf("non-letter suffix %q", value)
		}
	}
}

func TestCheckoutReturnURLPreservesCallbackAndSessionPlaceholder(t *testing.T) {
	success := checkoutReturnURL("https://console.example.test/admin/?topup=success", "order-123", true)
	if !strings.Contains(success, "topup=success") || !strings.Contains(success, "order_id=order-123") ||
		!strings.Contains(success, "session_id={CHECKOUT_SESSION_ID}") {
		t.Fatalf("unexpected success URL %q", success)
	}
	cancel := checkoutReturnURL("https://console.example.test/admin/?topup=cancel&session_id=stale", "order-123", false)
	if !strings.Contains(cancel, "topup=cancel") || !strings.Contains(cancel, "order_id=order-123") || strings.Contains(cancel, "session_id=") {
		t.Fatalf("unexpected cancel URL %q", cancel)
	}
}

func TestSettlementSpoolWritesOneDurableRecord(t *testing.T) {
	path := t.TempDir() + "/settlements.jsonl"
	service := &Service{settlementSpoolPath: path}
	event := domain.UsageEvent{RequestID: "req_spool_test", TenantID: "tenant", StartedAt: time.Now().UTC()}
	payload, err := json.Marshal(event)
	if err != nil {
		t.Fatal(err)
	}
	if err := service.appendSettlementSpool(payload); err != nil {
		t.Fatal(err)
	}
	contents, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	if strings.Count(string(contents), "req_spool_test") != 1 || !strings.HasSuffix(string(contents), "\n") {
		t.Fatalf("unexpected spool contents %q", contents)
	}
}

func TestWebhookRejectsInvalidSignatureBeforeProcessing(t *testing.T) {
	service := &Service{stripeWebhookSecret: "whsec_test"}
	request := httptest.NewRequest(http.MethodPost, "/billing/stripe/webhook", strings.NewReader(`{"id":"evt_fake"}`))
	request.Header.Set("Stripe-Signature", "invalid")
	response := httptest.NewRecorder()
	service.WebhookHandler().ServeHTTP(response, request)
	if response.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want 400", response.Code)
	}
}

func TestStripeWebhookCreditsPaidOrderExactlyOncePostgres(t *testing.T) {
	databaseURL := os.Getenv("AIGW_TEST_DATABASE_URL")
	if databaseURL == "" {
		t.Skip("AIGW_TEST_DATABASE_URL is not set")
	}
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	if err := controlplane.MigrateDatabase(ctx, databaseURL); err != nil {
		t.Fatal(err)
	}
	service, err := New(ctx, Options{
		DatabaseURL: databaseURL, Currency: "usd", MinTopUpMinor: 500, MaxTopUpMinor: 1_000_000,
		StripeEnabled: true, StripeAPIKey: "rk_test_placeholder", StripeWebhookSecret: "whsec_integration_test",
	})
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(service.Close)

	var tenantID string
	slug := fmt.Sprintf("stripe-%d", time.Now().UnixNano())
	if err := service.db.QueryRow(ctx, `INSERT INTO tenants (slug, name) VALUES ($1,'Stripe integration') RETURNING id::text`, slug).Scan(&tenantID); err != nil {
		t.Fatal(err)
	}
	eventID := fmt.Sprintf("evt_aigw_%d", time.Now().UnixNano())
	followupEventID := eventID + "_async"
	t.Cleanup(func() {
		cleanupCtx := context.Background()
		for _, statement := range []struct {
			query string
			arg   string
		}{
			{`DELETE FROM stripe_webhook_events WHERE event_id=$1`, eventID},
			{`DELETE FROM stripe_webhook_events WHERE event_id=$1`, followupEventID},
			{`DELETE FROM billing_ledger WHERE tenant_id=$1`, tenantID},
			{`DELETE FROM tenant_wallets WHERE tenant_id=$1`, tenantID},
			{`DELETE FROM topup_orders WHERE tenant_id=$1`, tenantID},
			{`DELETE FROM tenants WHERE id=$1`, tenantID},
		} {
			if _, cleanupErr := service.db.Exec(cleanupCtx, statement.query, statement.arg); cleanupErr != nil {
				t.Errorf("cleanup Stripe integration data: %v", cleanupErr)
			}
		}
	})
	const amountMinor int64 = 2500
	orderID, amountMicros, err := service.createTopUpOrder(ctx, CheckoutInput{TenantID: tenantID, AmountMinor: amountMinor})
	if err != nil {
		t.Fatal(err)
	}
	sessionID := fmt.Sprintf("cs_test_aigw_%d", time.Now().UnixNano())
	payload, err := json.Marshal(map[string]any{
		"id": eventID, "object": "event", "api_version": stripe.APIVersion,
		"type": string(stripe.EventTypeCheckoutSessionCompleted),
		"data": map[string]any{"object": map[string]any{
			"id": sessionID, "object": "checkout.session", "client_reference_id": orderID,
			"amount_total": amountMinor, "currency": "usd", "payment_status": "paid",
		}},
	})
	if err != nil {
		t.Fatal(err)
	}
	signed := webhook.GenerateTestSignedPayload(&webhook.UnsignedPayload{Payload: payload, Secret: service.stripeWebhookSecret})
	for delivery := 0; delivery < 2; delivery++ {
		request := httptest.NewRequest(http.MethodPost, "/billing/stripe/webhook", strings.NewReader(string(payload)))
		request.Header.Set("Stripe-Signature", signed.Header)
		response := httptest.NewRecorder()
		service.WebhookHandler().ServeHTTP(response, request)
		if response.Code != http.StatusOK {
			t.Fatalf("delivery %d status = %d, body = %s", delivery+1, response.Code, response.Body.String())
		}
	}
	if _, err := service.db.Exec(ctx, `UPDATE topup_orders SET status='refunded',refunded_micros=amount_micros WHERE id=$1`, orderID); err != nil {
		t.Fatal(err)
	}
	followupPayload, err := json.Marshal(map[string]any{
		"id": followupEventID, "object": "event", "api_version": stripe.APIVersion,
		"type": string(stripe.EventTypeCheckoutSessionAsyncPaymentSucceeded),
		"data": map[string]any{"object": map[string]any{
			"id": sessionID, "object": "checkout.session", "client_reference_id": orderID,
			"amount_total": amountMinor, "currency": "usd", "payment_status": "paid",
		}},
	})
	if err != nil {
		t.Fatal(err)
	}
	followupSigned := webhook.GenerateTestSignedPayload(&webhook.UnsignedPayload{Payload: followupPayload, Secret: service.stripeWebhookSecret})
	followupRequest := httptest.NewRequest(http.MethodPost, "/billing/stripe/webhook", strings.NewReader(string(followupPayload)))
	followupRequest.Header.Set("Stripe-Signature", followupSigned.Header)
	followupResponse := httptest.NewRecorder()
	service.WebhookHandler().ServeHTTP(followupResponse, followupRequest)
	if followupResponse.Code != http.StatusOK {
		t.Fatalf("follow-up status = %d, body = %s", followupResponse.Code, followupResponse.Body.String())
	}

	var balance int64
	if err := service.db.QueryRow(ctx, `SELECT balance_micros FROM tenant_wallets WHERE tenant_id=$1`, tenantID).Scan(&balance); err != nil {
		t.Fatal(err)
	}
	if balance != amountMicros {
		t.Fatalf("balance = %d, want %d", balance, amountMicros)
	}
	var ledgerCount, webhookCount int
	var orderStatus string
	if err := service.db.QueryRow(ctx, `SELECT count(*) FROM billing_ledger WHERE source_type='stripe_checkout' AND source_id=$1`, sessionID).Scan(&ledgerCount); err != nil {
		t.Fatal(err)
	}
	if err := service.db.QueryRow(ctx, `SELECT count(*) FROM stripe_webhook_events WHERE event_id IN ($1,$2)`, eventID, followupEventID).Scan(&webhookCount); err != nil {
		t.Fatal(err)
	}
	if err := service.db.QueryRow(ctx, `SELECT status FROM topup_orders WHERE id=$1`, orderID).Scan(&orderStatus); err != nil {
		t.Fatal(err)
	}
	if ledgerCount != 1 || webhookCount != 2 || orderStatus != "refunded" {
		t.Fatalf("ledger=%d webhook=%d order=%s, want 1/2/refunded", ledgerCount, webhookCount, orderStatus)
	}
}

func TestSettlementWorkerPersistsUsageAndReleasesReservationPostgres(t *testing.T) {
	databaseURL := os.Getenv("AIGW_TEST_DATABASE_URL")
	if databaseURL == "" {
		t.Skip("AIGW_TEST_DATABASE_URL is not set")
	}
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	if err := controlplane.MigrateDatabase(ctx, databaseURL); err != nil {
		t.Fatal(err)
	}
	service, err := New(ctx, Options{DatabaseURL: databaseURL, Currency: "usd", SettlementSpoolPath: t.TempDir() + "/settlements.jsonl"})
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(service.Close)
	slug := fmt.Sprintf("settle-%d", time.Now().UnixNano())
	var tenantID, projectID, keyID string
	if err := service.db.QueryRow(ctx, `INSERT INTO tenants (slug,name) VALUES ($1,'Settlement integration') RETURNING id::text`, slug).Scan(&tenantID); err != nil {
		t.Fatal(err)
	}
	if err := service.db.QueryRow(ctx, `INSERT INTO projects (tenant_id,slug,name) VALUES ($1,'default','Settlement') RETURNING id::text`, tenantID).Scan(&projectID); err != nil {
		t.Fatal(err)
	}
	keyHash := sha256.Sum256([]byte(slug))
	if err := service.db.QueryRow(ctx, `INSERT INTO api_keys (tenant_id,project_id,name,key_prefix,key_hash) VALUES ($1,$2,'integration','sk-test',$3) RETURNING id::text`, tenantID, projectID, keyHash[:]).Scan(&keyID); err != nil {
		t.Fatal(err)
	}
	requestID := fmt.Sprintf("req_settle_%d", time.Now().UnixNano())
	missingRequestID := requestID + "_missing_usage"
	t.Cleanup(func() {
		for _, statement := range []struct {
			query string
			arg   string
		}{
			{`DELETE FROM billing_ledger WHERE tenant_id=$1`, tenantID},
			{`DELETE FROM usage_monthly_rollups WHERE tenant_id=$1`, tenantID},
			{`DELETE FROM usage_events WHERE tenant_id=$1`, tenantID},
			{`DELETE FROM billing_settlement_jobs WHERE request_id=$1`, requestID},
			{`DELETE FROM billing_settlement_jobs WHERE request_id=$1`, missingRequestID},
			{`DELETE FROM billing_reservations WHERE request_id=$1`, requestID},
			{`DELETE FROM billing_reservations WHERE request_id=$1`, missingRequestID},
			{`DELETE FROM tenant_wallets WHERE tenant_id=$1`, tenantID},
			{`DELETE FROM api_keys WHERE id=$1`, keyID},
			{`DELETE FROM projects WHERE id=$1`, projectID},
			{`DELETE FROM tenants WHERE id=$1`, tenantID},
		} {
			if _, cleanupErr := service.db.Exec(context.Background(), statement.query, statement.arg); cleanupErr != nil {
				t.Errorf("cleanup settlement integration data: %v", cleanupErr)
			}
		}
	})
	if _, err := service.db.Exec(ctx, `INSERT INTO tenant_wallets (tenant_id,currency,balance_micros,reserved_micros) VALUES ($1,'usd',1000,20)`, tenantID); err != nil {
		t.Fatal(err)
	}
	if _, err := service.db.Exec(ctx, `INSERT INTO billing_reservations (request_id,tenant_id,project_id,key_id,public_model,currency,reserved_micros,input_price_micros_per_million,output_price_micros_per_million,cache_read_price_micros_per_million,cache_write_price_micros_per_million) VALUES ($1,$2,$3,$4,'demo/model','usd',20,1000000,1000000,0,0)`, requestID, tenantID, projectID, keyID); err != nil {
		t.Fatal(err)
	}
	if _, err := service.db.Exec(ctx, `INSERT INTO billing_settlement_jobs (request_id) VALUES ($1)`, requestID); err != nil {
		t.Fatal(err)
	}
	if err := service.EnqueueSettlement(ctx, domain.UsageEvent{RequestID: requestID, TenantID: tenantID, ProjectID: projectID, KeyID: keyID, PublicModel: "demo/model", Protocol: domain.ProtocolOpenAI, StatusCode: 200, Success: true, UsageReported: true, StartedAt: time.Now().UTC(), Usage: domain.Usage{InputTokens: 10}}); err != nil {
		t.Fatal(err)
	}
	processed, err := service.processSettlementJob(ctx)
	if err != nil || !processed {
		t.Fatalf("process settlement: processed=%v err=%v", processed, err)
	}
	var reservationStatus, jobStatus string
	var balance, reserved, charged, usageCount int64
	if err := service.db.QueryRow(ctx, `SELECT status,charged_micros FROM billing_reservations WHERE request_id=$1`, requestID).Scan(&reservationStatus, &charged); err != nil {
		t.Fatal(err)
	}
	if err := service.db.QueryRow(ctx, `SELECT status FROM billing_settlement_jobs WHERE request_id=$1`, requestID).Scan(&jobStatus); err != nil {
		t.Fatal(err)
	}
	if err := service.db.QueryRow(ctx, `SELECT balance_micros,reserved_micros FROM tenant_wallets WHERE tenant_id=$1`, tenantID).Scan(&balance, &reserved); err != nil {
		t.Fatal(err)
	}
	if err := service.db.QueryRow(ctx, `SELECT count(*) FROM usage_events WHERE request_id=$1`, requestID).Scan(&usageCount); err != nil {
		t.Fatal(err)
	}
	if reservationStatus != "settled" || jobStatus != "done" || balance != 990 || reserved != 0 || charged != 10 || usageCount != 1 {
		t.Fatalf("reservation=%s job=%s balance=%d reserved=%d charged=%d usage=%d", reservationStatus, jobStatus, balance, reserved, charged, usageCount)
	}

	if _, err := service.db.Exec(ctx, `UPDATE tenant_wallets SET reserved_micros=reserved_micros+30 WHERE tenant_id=$1`, tenantID); err != nil {
		t.Fatal(err)
	}
	if _, err := service.db.Exec(ctx, `INSERT INTO billing_reservations
		(request_id,tenant_id,project_id,key_id,public_model,currency,reserved_micros,input_price_micros_per_million,output_price_micros_per_million,cache_read_price_micros_per_million,cache_write_price_micros_per_million)
		VALUES ($1,$2,$3,$4,'demo/model','usd',30,1000000,1000000,0,0)`, missingRequestID, tenantID, projectID, keyID); err != nil {
		t.Fatal(err)
	}
	if _, err := service.db.Exec(ctx, `INSERT INTO billing_settlement_jobs (request_id) VALUES ($1)`, missingRequestID); err != nil {
		t.Fatal(err)
	}
	if err := service.EnqueueSettlement(ctx, domain.UsageEvent{RequestID: missingRequestID, TenantID: tenantID, ProjectID: projectID,
		KeyID: keyID, PublicModel: "demo/model", Protocol: domain.ProtocolOpenAI, StatusCode: 200, Success: true,
		UsageReported: false, StartedAt: time.Now().UTC()}); err != nil {
		t.Fatal(err)
	}
	processed, err = service.processSettlementJob(ctx)
	if err != nil || !processed {
		t.Fatalf("process missing-usage settlement: processed=%v err=%v", processed, err)
	}
	var missingReservationStatus, missingJobStatus, meteringStatus string
	if err := service.db.QueryRow(ctx, `SELECT status FROM billing_reservations WHERE request_id=$1`, missingRequestID).Scan(&missingReservationStatus); err != nil {
		t.Fatal(err)
	}
	if err := service.db.QueryRow(ctx, `SELECT status FROM billing_settlement_jobs WHERE request_id=$1`, missingRequestID).Scan(&missingJobStatus); err != nil {
		t.Fatal(err)
	}
	if err := service.db.QueryRow(ctx, `SELECT balance_micros,reserved_micros FROM tenant_wallets WHERE tenant_id=$1`, tenantID).Scan(&balance, &reserved); err != nil {
		t.Fatal(err)
	}
	if err := service.db.QueryRow(ctx, `SELECT metering_status FROM usage_events WHERE request_id=$1`, missingRequestID).Scan(&meteringStatus); err != nil {
		t.Fatal(err)
	}
	if missingReservationStatus != "metering_failed" || missingJobStatus != "done" || balance != 990 || reserved != 30 || meteringStatus != "missing" {
		t.Fatalf("missing usage reservation=%s job=%s balance=%d reserved=%d metering=%s", missingReservationStatus, missingJobStatus, balance, reserved, meteringStatus)
	}
}