package postgres

import (
	"context"
	"crypto/sha256"
	"database/sql"
	"encoding/hex"
	"testing"
	"time"

	"github.com/orchard9/rdev/internal/domain"
	"github.com/orchard9/rdev/internal/testutil"
)

// createTestAPIKey creates a test API key and returns its ID.
func createTestAPIKey(t *testing.T, db *sql.DB, name string) string {
	t.Helper()
	repo := NewAPIKeyRepository(db)
	ctx := context.Background()

	key := &domain.APIKey{
		Name:      "test-ratelimit-" + name,
		KeyPrefix: "rl123456",
		Scopes:    []domain.Scope{domain.ScopeProjectsRead},
		CreatedBy: "test",
	}

	h := sha256.Sum256([]byte("ratelimit-key-" + name))
	keyHash := hex.EncodeToString(h[:])

	err := repo.Create(ctx, key, keyHash)
	if err != nil {
		t.Fatalf("create test API key: %v", err)
	}

	return string(key.ID)
}

func cleanupTestRateLimits(t *testing.T, db *sql.DB) {
	t.Helper()
	// Clean rate limit state for test keys
	_, err := db.Exec(`
		DELETE FROM rate_limit_state
		WHERE api_key_id IN (SELECT id FROM api_keys WHERE name LIKE 'test-ratelimit-%')
	`)
	if err != nil {
		t.Logf("cleanup test rate limits: %v", err)
	}
	// Clean up test API keys
	testutil.CleanupTestKeys(t, db)
}

func TestRateLimiter_RecordRequest(t *testing.T) {
	db := testutil.TestDB(t)
	t.Cleanup(func() { cleanupTestRateLimits(t, db) })

	limiter := NewRateLimiter(db)
	ctx := context.Background()

	t.Run("records first request", func(t *testing.T) {
		keyID := createTestAPIKey(t, db, "record-first")

		err := limiter.RecordRequest(ctx, keyID)
		if err != nil {
			t.Fatalf("RecordRequest() error = %v", err)
		}

		// Verify by checking limits
		result, err := limiter.CheckLimit(ctx, keyID)
		if err != nil {
			t.Fatalf("CheckLimit() error = %v", err)
		}

		// Should have recorded one request
		if result.RemainingMinute >= result.LimitMinute {
			t.Error("RemainingMinute should be less than LimitMinute after recording a request")
		}
	})

	t.Run("increments existing request count", func(t *testing.T) {
		keyID := createTestAPIKey(t, db, "record-increment")

		// Record multiple requests
		for i := 0; i < 3; i++ {
			err := limiter.RecordRequest(ctx, keyID)
			if err != nil {
				t.Fatalf("RecordRequest() iteration %d error = %v", i, err)
			}
		}

		result, _ := limiter.CheckLimit(ctx, keyID)

		expectedRemaining := result.LimitMinute - 3
		if result.RemainingMinute != expectedRemaining {
			t.Errorf("RemainingMinute = %d, want %d", result.RemainingMinute, expectedRemaining)
		}
	})
}

func TestRateLimiter_CheckLimit(t *testing.T) {
	db := testutil.TestDB(t)
	t.Cleanup(func() { cleanupTestRateLimits(t, db) })

	limiter := NewRateLimiter(db)
	ctx := context.Background()

	t.Run("allows request when under limit", func(t *testing.T) {
		keyID := createTestAPIKey(t, db, "check-under")

		result, err := limiter.CheckLimit(ctx, keyID)
		if err != nil {
			t.Fatalf("CheckLimit() error = %v", err)
		}

		if !result.Allowed {
			t.Error("CheckLimit() should allow request when under limit")
		}
		if result.RemainingMinute <= 0 {
			t.Error("RemainingMinute should be positive")
		}
		if result.RemainingHour <= 0 {
			t.Error("RemainingHour should be positive")
		}
	})

	t.Run("denies request when minute limit exceeded", func(t *testing.T) {
		keyID := createTestAPIKey(t, db, "check-minute-exceeded")

		// Get the limit
		limits, _ := limiter.GetLimits(ctx, keyID)

		// Record enough requests to exceed minute limit
		for i := 0; i < limits.PerMinute; i++ {
			_ = limiter.RecordRequest(ctx, keyID)
		}

		result, err := limiter.CheckLimit(ctx, keyID)
		if err != nil {
			t.Fatalf("CheckLimit() error = %v", err)
		}

		if result.Allowed {
			t.Error("CheckLimit() should deny request when minute limit exceeded")
		}
		if result.RetryAfter <= 0 {
			t.Error("RetryAfter should be positive when denied")
		}
		if result.RemainingMinute != 0 {
			t.Errorf("RemainingMinute = %d, want 0", result.RemainingMinute)
		}
	})

	t.Run("returns correct reset times", func(t *testing.T) {
		keyID := createTestAPIKey(t, db, "check-reset")

		result, err := limiter.CheckLimit(ctx, keyID)
		if err != nil {
			t.Fatalf("CheckLimit() error = %v", err)
		}

		now := time.Now()

		// ResetMinute should be within the next minute
		if result.ResetMinute.Before(now) {
			t.Error("ResetMinute should be in the future")
		}
		if result.ResetMinute.After(now.Add(time.Minute + time.Second)) {
			t.Error("ResetMinute should be within ~1 minute from now")
		}

		// ResetHour should be within the next hour
		if result.ResetHour.Before(now) {
			t.Error("ResetHour should be in the future")
		}
		if result.ResetHour.After(now.Add(time.Hour + time.Second)) {
			t.Error("ResetHour should be within ~1 hour from now")
		}
	})
}

func TestRateLimiter_GetLimits(t *testing.T) {
	db := testutil.TestDB(t)
	t.Cleanup(func() { cleanupTestRateLimits(t, db) })

	limiter := NewRateLimiter(db)
	ctx := context.Background()

	t.Run("returns default limits for unknown key", func(t *testing.T) {
		// Use a UUID that doesn't exist
		limits, err := limiter.GetLimits(ctx, "00000000-0000-0000-0000-000000000000")
		if err != nil {
			t.Fatalf("GetLimits() error = %v", err)
		}

		defaults := domain.DefaultRateLimitConfig()
		if limits.PerMinute != defaults.PerMinute {
			t.Errorf("PerMinute = %d, want %d", limits.PerMinute, defaults.PerMinute)
		}
		if limits.PerHour != defaults.PerHour {
			t.Errorf("PerHour = %d, want %d", limits.PerHour, defaults.PerHour)
		}
	})

	t.Run("returns limits from existing key", func(t *testing.T) {
		keyID := createTestAPIKey(t, db, "get-limits")

		limits, err := limiter.GetLimits(ctx, keyID)
		if err != nil {
			t.Fatalf("GetLimits() error = %v", err)
		}

		// Should return defaults since we didn't set custom limits
		defaults := domain.DefaultRateLimitConfig()
		if limits.PerMinute != defaults.PerMinute {
			t.Errorf("PerMinute = %d, want %d", limits.PerMinute, defaults.PerMinute)
		}
	})
}

func TestRateLimiter_Cleanup(t *testing.T) {
	db := testutil.TestDB(t)
	t.Cleanup(func() { cleanupTestRateLimits(t, db) })

	limiter := NewRateLimiter(db)
	ctx := context.Background()

	t.Run("cleanup runs without error", func(t *testing.T) {
		// Create some rate limit entries
		keyID := createTestAPIKey(t, db, "cleanup-entry")
		_ = limiter.RecordRequest(ctx, keyID)

		err := limiter.Cleanup(ctx)
		if err != nil {
			t.Fatalf("Cleanup() error = %v", err)
		}

		// Recent entries should not be deleted
		result, _ := limiter.CheckLimit(ctx, keyID)
		if result.RemainingMinute >= result.LimitMinute {
			// If the entry was cleaned up, remaining would equal limit
			t.Log("Note: Recent rate limit entry was not cleaned up (expected behavior)")
		}
	})
}

func TestRateLimiter_WindowHandling(t *testing.T) {
	db := testutil.TestDB(t)
	t.Cleanup(func() { cleanupTestRateLimits(t, db) })

	limiter := NewRateLimiter(db)
	ctx := context.Background()

	t.Run("minute and hour windows are tracked separately", func(t *testing.T) {
		keyID := createTestAPIKey(t, db, "windows")

		// Record a request
		_ = limiter.RecordRequest(ctx, keyID)

		result, err := limiter.CheckLimit(ctx, keyID)
		if err != nil {
			t.Fatalf("CheckLimit() error = %v", err)
		}

		// Both counters should reflect one request
		expectedMinuteRemaining := result.LimitMinute - 1
		expectedHourRemaining := result.LimitHour - 1

		if result.RemainingMinute != expectedMinuteRemaining {
			t.Errorf("RemainingMinute = %d, want %d", result.RemainingMinute, expectedMinuteRemaining)
		}
		if result.RemainingHour != expectedHourRemaining {
			t.Errorf("RemainingHour = %d, want %d", result.RemainingHour, expectedHourRemaining)
		}
	})
}

func TestRateLimiter_ConcurrentRequests(t *testing.T) {
	db := testutil.TestDB(t)
	t.Cleanup(func() { cleanupTestRateLimits(t, db) })

	limiter := NewRateLimiter(db)
	ctx := context.Background()
	keyID := createTestAPIKey(t, db, "concurrent")

	// Run concurrent requests
	const numRequests = 10
	done := make(chan error, numRequests)

	for i := 0; i < numRequests; i++ {
		go func() {
			done <- limiter.RecordRequest(ctx, keyID)
		}()
	}

	// Wait for all requests to complete
	for i := 0; i < numRequests; i++ {
		if err := <-done; err != nil {
			t.Errorf("Concurrent RecordRequest() error = %v", err)
		}
	}

	// Verify the count
	result, err := limiter.CheckLimit(ctx, keyID)
	if err != nil {
		t.Fatalf("CheckLimit() error = %v", err)
	}

	expectedRemaining := result.LimitMinute - numRequests
	if result.RemainingMinute != expectedRemaining {
		t.Errorf("RemainingMinute = %d, want %d (all concurrent requests should be counted)", result.RemainingMinute, expectedRemaining)
	}
}