package service

import (
	"context"
	"fmt"
	"time"

	"apskel-pos-be/internal/contract"
	"apskel-pos-be/internal/models"
	"apskel-pos-be/internal/processor"
)

type CampaignService interface {
	CreateCampaign(ctx context.Context, req *contract.CreateCampaignRequest) (*models.CampaignResponse, error)
	GetCampaign(ctx context.Context, id string) (*models.CampaignResponse, error)
	ListCampaigns(ctx context.Context, req *contract.ListCampaignsRequest) (*models.ListCampaignsResponse, error)
	UpdateCampaign(ctx context.Context, req *contract.UpdateCampaignRequest) (*models.CampaignResponse, error)
	DeleteCampaign(ctx context.Context, id string) error
	GetActiveCampaigns(ctx context.Context) ([]models.CampaignResponse, error)
	GetCampaignsForApp(ctx context.Context) ([]models.CampaignResponse, error)
}

type campaignService struct {
	campaignProcessor processor.CampaignProcessor
}

func NewCampaignService(campaignProcessor processor.CampaignProcessor) CampaignService {
	return &campaignService{
		campaignProcessor: campaignProcessor,
	}
}

func (s *campaignService) CreateCampaign(ctx context.Context, req *contract.CreateCampaignRequest) (*models.CampaignResponse, error) {
	// Validate campaign type
	if err := s.validateCampaignType(req.Type); err != nil {
		return nil, fmt.Errorf("validation failed: %w", err)
	}

	// Validate date range
	if err := s.validateDateRange(req.StartDate, req.EndDate); err != nil {
		return nil, fmt.Errorf("validation failed: %w", err)
	}

	// Validate rules
	if err := s.validateCampaignRules(req.Rules); err != nil {
		return nil, fmt.Errorf("validation failed: %w", err)
	}

	// Validate position
	if req.Position < 0 {
		return nil, fmt.Errorf("position cannot be negative")
	}

	// Create campaign
	response, err := s.campaignProcessor.CreateCampaign(ctx, req)
	if err != nil {
		return nil, fmt.Errorf("failed to create campaign: %w", err)
	}

	return response, nil
}

func (s *campaignService) GetCampaign(ctx context.Context, id string) (*models.CampaignResponse, error) {
	if id == "" {
		return nil, fmt.Errorf("campaign ID is required")
	}

	response, err := s.campaignProcessor.GetCampaign(ctx, id)
	if err != nil {
		return nil, fmt.Errorf("failed to get campaign: %w", err)
	}

	return response, nil
}

func (s *campaignService) ListCampaigns(ctx context.Context, req *contract.ListCampaignsRequest) (*models.ListCampaignsResponse, error) {
	// Set default pagination
	if req.Page <= 0 {
		req.Page = 1
	}
	if req.Limit <= 0 {
		req.Limit = 10
	}
	if req.Limit > 100 {
		req.Limit = 100
	}

	// Validate campaign type filter if provided
	if req.Type != "" {
		if err := s.validateCampaignType(req.Type); err != nil {
			return nil, fmt.Errorf("validation failed: %w", err)
		}
	}

	response, err := s.campaignProcessor.ListCampaigns(ctx, req)
	if err != nil {
		return nil, fmt.Errorf("failed to list campaigns: %w", err)
	}

	return response, nil
}

func (s *campaignService) UpdateCampaign(ctx context.Context, req *contract.UpdateCampaignRequest) (*models.CampaignResponse, error) {
	if req.ID.String() == "" {
		return nil, fmt.Errorf("campaign ID is required")
	}

	// Validate campaign type
	if err := s.validateCampaignType(req.Type); err != nil {
		return nil, fmt.Errorf("validation failed: %w", err)
	}

	// Validate date range
	if err := s.validateDateRange(req.StartDate, req.EndDate); err != nil {
		return nil, fmt.Errorf("validation failed: %w", err)
	}

	// Validate rules
	if err := s.validateCampaignRules(req.Rules); err != nil {
		return nil, fmt.Errorf("validation failed: %w", err)
	}

	// Validate position
	if req.Position < 0 {
		return nil, fmt.Errorf("position cannot be negative")
	}

	response, err := s.campaignProcessor.UpdateCampaign(ctx, req)
	if err != nil {
		return nil, fmt.Errorf("failed to update campaign: %w", err)
	}

	return response, nil
}

func (s *campaignService) DeleteCampaign(ctx context.Context, id string) error {
	if id == "" {
		return fmt.Errorf("campaign ID is required")
	}

	err := s.campaignProcessor.DeleteCampaign(ctx, id)
	if err != nil {
		return fmt.Errorf("failed to delete campaign: %w", err)
	}

	return nil
}

func (s *campaignService) GetActiveCampaigns(ctx context.Context) ([]models.CampaignResponse, error) {
	campaigns, err := s.campaignProcessor.GetActiveCampaigns(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to get active campaigns: %w", err)
	}

	return campaigns, nil
}

func (s *campaignService) GetCampaignsForApp(ctx context.Context) ([]models.CampaignResponse, error) {
	campaigns, err := s.campaignProcessor.GetCampaignsForApp(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to get campaigns for app: %w", err)
	}

	return campaigns, nil
}

func (s *campaignService) validateCampaignType(campaignType string) error {
	validTypes := []string{"REWARD", "POINTS", "TOKENS", "MIXED"}
	for _, validType := range validTypes {
		if campaignType == validType {
			return nil
		}
	}
	return fmt.Errorf("invalid campaign type: %s. Valid types are: REWARD, POINTS, TOKENS, MIXED", campaignType)
}

func (s *campaignService) validateDateRange(startDate, endDate time.Time) error {
	if startDate.IsZero() {
		return fmt.Errorf("start date is required")
	}
	if endDate.IsZero() {
		return fmt.Errorf("end date is required")
	}
	if startDate.After(endDate) {
		return fmt.Errorf("start date cannot be after end date")
	}
	if startDate.Before(time.Now()) {
		return fmt.Errorf("start date cannot be in the past")
	}
	return nil
}

func (s *campaignService) validateCampaignRules(rules []contract.CampaignRuleStruct) error {
	if len(rules) == 0 {
		return fmt.Errorf("at least one rule is required")
	}

	for i, rule := range rules {
		if err := s.validateRuleType(rule.RuleType); err != nil {
			return fmt.Errorf("invalid rule type in rule %d: %w", i+1, err)
		}

		if err := s.validateRewardType(rule.RewardType); err != nil {
			return fmt.Errorf("invalid reward type in rule %d: %w", i+1, err)
		}

		// Validate reward value based on reward type
		if rule.RewardType == "POINTS" || rule.RewardType == "TOKENS" {
			if rule.RewardValue == nil || *rule.RewardValue <= 0 {
				return fmt.Errorf("reward value must be positive for %s type in rule %d", rule.RewardType, i+1)
			}
		}

		// Validate reward reference ID for REWARD type
		if rule.RewardType == "REWARD" {
			if rule.RewardRefID == nil {
				return fmt.Errorf("reward reference ID is required for REWARD type in rule %d", i+1)
			}
		}

		_ = i // Avoid unused variable warning
	}

	return nil
}

func (s *campaignService) validateRuleType(ruleType string) error {
	validTypes := []string{"TIER", "SPEND", "PRODUCT", "CATEGORY", "DAY", "LOCATION"}
	for _, validType := range validTypes {
		if ruleType == validType {
			return nil
		}
	}
	return fmt.Errorf("invalid rule type: %s. Valid types are: TIER, SPEND, PRODUCT, CATEGORY, DAY, LOCATION", ruleType)
}

func (s *campaignService) validateRewardType(rewardType string) error {
	validTypes := []string{"POINTS", "TOKENS", "REWARD"}
	for _, validType := range validTypes {
		if rewardType == validType {
			return nil
		}
	}
	return fmt.Errorf("invalid reward type: %s. Valid types are: POINTS, TOKENS, REWARD", rewardType)
}