package rpc

import (
	"context"
	"fmt"
	log "github.com/sirupsen/logrus"
	"net/http"
	"time"

	"git.itzana.me/StrafesNET/dev-service/pkg/cache"
	"git.itzana.me/StrafesNET/dev-service/pkg/datastore"
	"git.itzana.me/StrafesNET/dev-service/pkg/model"
	"git.itzana.me/StrafesNET/dev-service/pkg/ratelimit"
	"git.itzana.me/strafesnet/go-grpc/dev"
)

// Error messages
const (
	ErrEmptyAPIKey       = "empty API key"
	ErrEmptyService      = "empty service name"
	ErrEmptyPermission   = "empty permission name"
	ErrAppInactive       = "application is disabled"
	ErrUserInactive      = "user is disabled"
	ErrRateLimitExceeded = "rate limit exceeded"
	ErrUnauthorized      = "unauthorized request"
)

// Cache settings
const (
	ApplicationCacheDuration = 30 * time.Second
)

// Dev implements the DevServiceServer interface
type Dev struct {
	*dev.UnimplementedDevServiceServer
	Store   datastore.Datastore
	Limiter *ratelimit.RateLimit
	Cache   *cache.Cache
}

// Validate checks if an API key is valid and has the required permissions
func (d Dev) Validate(ctx context.Context, request *dev.APIValidationRequest) (*dev.APIValidationResponse, error) {
	// Check for context cancellation
	if ctx.Err() != nil {
		return errorResponse(fmt.Errorf("context error: %w", ctx.Err()), http.StatusInternalServerError)
	}

	// Validate request parameters
	if err := d.validateRequestParams(request); err != nil {
		return errorResponse(err, http.StatusBadRequest)
	}

	// Get application data
	appCache, err := d.getApplicationData(ctx, request.Key)
	if err != nil {
		return errorResponse(err, http.StatusInternalServerError)
	}

	// Check if user is disabled
	if !appCache.UserActive {
		return buildResponse(appCache, &ratelimit.RateLimitStatus{}, false, ErrUserInactive, http.StatusForbidden), nil
	}

	// Check if application is active
	if !appCache.Active {
		return buildResponse(appCache, &ratelimit.RateLimitStatus{}, false, ErrAppInactive, http.StatusForbidden), nil
	}

	// Check rate limits
	limit, err := d.checkRateLimits(ctx, appCache)
	if err != nil {
		return buildResponse(appCache, createDefaultRateLimitStatus(), false,
			fmt.Sprintf("failed to check rate limits: %v", err), http.StatusInternalServerError), nil
	}

	// Rate limit exceeded
	if !limit.Allowed {
		return buildResponse(appCache, limit, false, ErrRateLimitExceeded, http.StatusTooManyRequests), nil
	}

	// Check permission
	if hasRequiredPermission(appCache.Permissions, request.Service, request.Permission) {
		log.WithFields(log.Fields{
			"service":     request.Service,
			"permission":  request.Permission,
			"resource":    request.Resource,
			"ip":          request.IP,
			"user":        appCache.UserID,
			"application": appCache.Name,
		}).Info(
			"request accepted",
		)

		return buildResponse(appCache, limit, true, "", 0), nil
	}

	return buildResponse(appCache, limit, false, ErrUnauthorized, http.StatusUnauthorized), nil
}

// validateRequestParams validates the basic parameters of the request
func (d Dev) validateRequestParams(request *dev.APIValidationRequest) error {
	if request.Key == "" {
		return fmt.Errorf(ErrEmptyAPIKey)
	}
	if request.Service == "" {
		return fmt.Errorf(ErrEmptyService)
	}
	if request.Permission == "" {
		return fmt.Errorf(ErrEmptyPermission)
	}
	return nil
}

// checkRateLimits checks if the application has exceeded its rate limits
func (d Dev) checkRateLimits(ctx context.Context, appCache *model.ApplicationCache) (*ratelimit.RateLimitStatus, error) {
	rateLimitConfig := ratelimit.RateLimitConfig{
		BurstLimit:           appCache.RateLimit.BurstLimit,
		BurstDurationSeconds: appCache.RateLimit.BurstDuration,
		DailyLimit:           appCache.RateLimit.DailyLimit,
		MonthlyLimit:         appCache.RateLimit.MonthlyLimit,
	}

	return d.Limiter.CheckRateLimits(ctx, appCache.UserID, rateLimitConfig)
}

// createDefaultRateLimitStatus creates a default rate limit status with all limits at zero
func createDefaultRateLimitStatus() *ratelimit.RateLimitStatus {
	return &ratelimit.RateLimitStatus{
		Allowed:          false,
		RemainingBurst:   0,
		RemainingDaily:   0,
		RemainingMonthly: 0,
	}
}

// getApplicationData retrieves application data from cache or datastore
func (d Dev) getApplicationData(ctx context.Context, apiKey string) (*model.ApplicationCache, error) {
	// Check for context cancellation
	if ctx.Err() != nil {
		return nil, fmt.Errorf("context error: %w", ctx.Err())
	}

	// Try to get from cache first
	appCache, err := d.Cache.GetApplicationByAPIKey(ctx, apiKey)
	if err == nil {
		return appCache, nil
	}

	// Not in cache, retrieve from store
	app, err := d.Store.GetApplicationByAPIKey(ctx, apiKey)
	if err != nil {
		return nil, fmt.Errorf("failed to retrieve application: %w", err)
	}

	user, err := d.Store.GetUser(ctx, app.UserID)
	if err != nil {
		return nil, fmt.Errorf("failed to retrieve user: %w", err)
	}

	appCache = &model.ApplicationCache{
		Name:        app.Name,
		UserID:      app.UserID,
		APIKey:      app.APIKey,
		Permissions: app.Permissions,
		Active:      app.Active,
		UserActive:  user.Active,
		RateLimit:   user.RateLimit,
	}

	// Cache the application data - log the error but don't fail the operation
	if err := d.Cache.SetApplicationByAPIKey(ctx, appCache, ApplicationCacheDuration); err != nil {
		// Log the error but continue since we have the data
		fmt.Printf("warning: failed to cache application: %v\n", err)
	}

	return appCache, nil
}

// errorResponse creates a standardized error response
func errorResponse(err error, statusCode int32) (*dev.APIValidationResponse, error) {
	return &dev.APIValidationResponse{
		Valid:        false,
		ErrorMessage: err.Error(),
		StatusCode:   statusCode,
	}, nil
}

// hasRequiredPermission checks if the permissions list contains the required service and permission
func hasRequiredPermission(permissions []model.Permission, service, permissionName string) bool {
	for _, p := range permissions {
		if p.PermissionName == permissionName && p.Service == service {
			return true
		}
	}
	return false
}

// buildResponse constructs a validation response with common fields
func buildResponse(app *model.ApplicationCache, limit *ratelimit.RateLimitStatus, valid bool, errorMsg string, statusCode int32) *dev.APIValidationResponse {
	return &dev.APIValidationResponse{
		Valid:                valid,
		ErrorMessage:         errorMsg,
		StatusCode:           statusCode,
		RemainingBurst:       limit.RemainingBurst,
		RemainingDaily:       limit.RemainingDaily,
		RemainingMonthly:     limit.RemainingMonthly,
		BurstLimit:           app.RateLimit.BurstLimit,
		BurstDurationSeconds: app.RateLimit.BurstDuration,
		DailyLimit:           app.RateLimit.DailyLimit,
		MonthlyLimit:         app.RateLimit.MonthlyLimit,
		UserID:               app.UserID,
		Application:          app.Name,
	}
}