package service

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"strings"
	"time"

	"gorm.io/gorm"

	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/repository"
	"github.com/gochat/gochat/internal/worker"
	applogger "github.com/gochat/gochat/pkg/logger"
	pkgvalidator "github.com/gochat/gochat/pkg/validator"
)

// CsatTemplateService implements business logic for CSAT template management.
// Reference: Chatwoot app/controllers/api/v1/accounts/inboxes/inbox_csat_templates_controller.rb
// CSAT templates are singular resources per inbox — show (get template status), create (submit template),
// and analyze (check template quality via Captain AI).
type CsatTemplateService struct {
	repo     *repository.CsatTemplateRepo
	provider CsatTemplateProvider
	worker   *worker.WorkerPool
}

// NewCsatTemplateService creates a new CsatTemplate service.
func NewCsatTemplateService(repo *repository.CsatTemplateRepo) *CsatTemplateService {
	return &CsatTemplateService{repo: repo, provider: defaultCsatTemplateProvider{}}
}

func (s *CsatTemplateService) SetWorkerPool(wp *worker.WorkerPool) {
	s.worker = wp
	RegisterCsatTemplateJobs(wp, s)
}

func (s *CsatTemplateService) SetProvider(provider CsatTemplateProvider) {
	if provider != nil {
		s.provider = provider
	}
}

// CreateCsatTemplateRequest is the DTO for creating a CSAT template.
// Reference: Chatwoot InboxCsatTemplatesController#create — params: {message}
type CreateCsatTemplateRequest struct {
	Message    string `json:"message" validate:"required,min=1"`
	ButtonText string `json:"button_text,omitempty"`
	Language   string `json:"language,omitempty"`
}

// AnalyzeCsatTemplateRequest is the DTO for analyzing a CSAT template.
// Reference: Chatwoot InboxCsatTemplatesController#analyze — params: {message}
type AnalyzeCsatTemplateRequest struct {
	Message    string `json:"message" validate:"required,min=1"`
	ButtonText string `json:"button_text,omitempty"`
	Language   string `json:"language,omitempty"`
}

type CsatTemplateProvider interface {
	CreateTemplate(ctx context.Context, inbox *model.Inbox, template *model.CsatTemplate, req CreateCsatTemplateRequest) (*CsatTemplateProviderResult, error)
	GetTemplateStatus(ctx context.Context, inbox *model.Inbox, template *model.CsatTemplate) (*CsatTemplateProviderResult, error)
}

type CsatTemplateProviderResult struct {
	TemplateExists bool
	Status         string
	TemplateName   string
	TemplateID     string
	FriendlyName   string
	ContentSID     string
	ApprovalSID    string
	Language       string
	Error          string
	ResponseBody   string
}

type CsatTemplateStatusResult struct {
	TemplateExists bool   `json:"template_exists"`
	Status         string `json:"status,omitempty"`
	TemplateName   string `json:"template_name,omitempty"`
	TemplateID     string `json:"template_id,omitempty"`
	FriendlyName   string `json:"friendly_name,omitempty"`
	ContentSID     string `json:"content_sid,omitempty"`
	Language       string `json:"language,omitempty"`
	Error          string `json:"error,omitempty"`
}

// CsatTemplateAnalysisResult represents the result of a CSAT template quality analysis.
// Placeholder implementation — real analysis requires Captain AI integration (WhatsApp template validation).
type CsatTemplateAnalysisResult struct {
	Quality     string   `json:"quality"`     // e.g. "good", "poor", "needs_improvement"
	Suggestions []string `json:"suggestions"` // improvement suggestions
	IsApproved  bool     `json:"is_approved"` // whether template would likely pass WhatsApp approval
	Message     string   `json:"message"`     // original message analyzed
}

// ShowTemplateStatus retrieves the CSAT template status for an inbox.
// If no template exists, returns nil to indicate "no template configured".
// Reference: Chatwoot InboxCsatTemplatesController#show
func (s *CsatTemplateService) ShowTemplateStatus(ctx context.Context, inboxID uint) (*model.CsatTemplate, error) {
	template, err := s.repo.FindByInbox(ctx, inboxID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			// No template configured — return nil to indicate "no template" (handler will return empty response)
			return nil, nil
		}
		return nil, err
	}
	return template, nil
}

func (s *CsatTemplateService) ShowTemplateStatusResult(ctx context.Context, inboxID uint) (*CsatTemplateStatusResult, error) {
	template, err := s.repo.FindByInbox(ctx, inboxID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return &CsatTemplateStatusResult{TemplateExists: false}, nil
		}
		return nil, err
	}
	var inbox model.Inbox
	if err := s.repo.DB().WithContext(ctx).First(&inbox, inboxID).Error; err != nil {
		return nil, err
	}
	result, err := s.provider.GetTemplateStatus(ctx, &inbox, template)
	if err != nil {
		return &CsatTemplateStatusResult{TemplateExists: false, Error: err.Error()}, nil
	}
	if result == nil || !result.TemplateExists {
		status := &CsatTemplateStatusResult{TemplateExists: false}
		if result != nil {
			status.Error = result.Error
		}
		return status, nil
	}
	return &CsatTemplateStatusResult{
		TemplateExists: true,
		Status:         providerStatusOrPending(result.Status),
		TemplateName:   result.TemplateName,
		TemplateID:     result.TemplateID,
		FriendlyName:   result.FriendlyName,
		ContentSID:     result.ContentSID,
		Language:       result.Language,
	}, nil
}

// CreateTemplate creates a new CSAT template for an inbox.
// If a template already exists for the inbox, updates it instead.
// Reference: Chatwoot InboxCsatTemplatesController#create
func (s *CsatTemplateService) CreateTemplate(ctx context.Context, inboxID uint, req CreateCsatTemplateRequest) (*model.CsatTemplate, error) {
	if err := pkgvalidator.ValidateStruct(req); err != nil {
		return nil, err
	}

	// Check if template already exists for this inbox
	existing, err := s.repo.FindByInbox(ctx, inboxID)
	if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, err
	}

	if existing != nil {
		// Update existing template
		existing.Message = req.Message
		existing.Status = "pending" // Reset status to pending after message change
		if err := s.repo.Update(ctx, existing); err != nil {
			return nil, err
		}
		if err := s.enqueueOrCreateProviderTemplate(ctx, existing, req); err != nil {
			return existing, err
		}
		if s.worker == nil {
			existing, _ = s.repo.FindByID(ctx, existing.ID)
		}
		applogger.L().Infof("CSAT template updated for inbox %d", inboxID)
		return existing, nil
	}

	// Create new template
	template := &model.CsatTemplate{
		InboxID: inboxID,
		Message: req.Message,
		Status:  "pending",
	}
	if err := s.repo.Create(ctx, template); err != nil {
		return nil, err
	}
	if err := s.enqueueOrCreateProviderTemplate(ctx, template, req); err != nil {
		return template, err
	}
	if s.worker == nil {
		template, _ = s.repo.FindByID(ctx, template.ID)
	}
	applogger.L().Infof("CSAT template created for inbox %d", inboxID)
	return template, nil
}

func (s *CsatTemplateService) enqueueOrCreateProviderTemplate(ctx context.Context, template *model.CsatTemplate, req CreateCsatTemplateRequest) error {
	if s.worker != nil {
		_, err := s.worker.Enqueue(ctx, TaskTypeCsatTemplateCreate, csatTemplateCreateJob{TemplateID: template.ID, Request: req}, worker.WithQueue("automation"), worker.WithMaxAttempts(3), worker.WithIdempotencyKey(fmt.Sprintf("csat-template:%d:%d", template.ID, template.UpdatedAt.UnixNano())))
		return err
	}
	return s.performTemplateCreate(ctx, template.ID, req)
}

func (s *CsatTemplateService) performTemplateCreate(ctx context.Context, templateID uint, req CreateCsatTemplateRequest) error {
	template, err := s.repo.FindByID(ctx, templateID)
	if err != nil {
		return err
	}
	var inbox model.Inbox
	if err := s.repo.DB().WithContext(ctx).First(&inbox, template.InboxID).Error; err != nil {
		return err
	}
	result, err := s.provider.CreateTemplate(ctx, &inbox, template, req)
	if err != nil {
		template.Status = "failed"
		_ = s.repo.Update(ctx, template)
		return err
	}
	template.Status = providerStatusOrPending(result.Status)
	if err := s.repo.Update(ctx, template); err != nil {
		return err
	}
	return s.updateInboxCsatTemplateConfig(ctx, &inbox, result)
}

func (s *CsatTemplateService) updateInboxCsatTemplateConfig(ctx context.Context, inbox *model.Inbox, result *CsatTemplateProviderResult) error {
	if result == nil || !result.TemplateExists {
		return nil
	}
	var config map[string]any
	if strings.TrimSpace(inbox.CsatConfig) != "" {
		_ = json.Unmarshal([]byte(inbox.CsatConfig), &config)
	}
	if config == nil {
		config = map[string]any{}
	}
	templateData := map[string]any{"status": providerStatusOrPending(result.Status), "created_at": time.Now().UTC().Format(time.RFC3339)}
	if result.Language != "" {
		templateData["language"] = result.Language
	}
	if result.TemplateName != "" {
		templateData["name"] = result.TemplateName
	}
	if result.TemplateID != "" {
		templateData["template_id"] = result.TemplateID
	}
	if result.FriendlyName != "" {
		templateData["friendly_name"] = result.FriendlyName
	}
	if result.ContentSID != "" {
		templateData["content_sid"] = result.ContentSID
	}
	if result.ApprovalSID != "" {
		templateData["approval_sid"] = result.ApprovalSID
	}
	config["template"] = templateData
	encoded, err := json.Marshal(config)
	if err != nil {
		return err
	}
	return s.repo.DB().WithContext(ctx).Model(&model.Inbox{}).Where("id = ?", inbox.ID).Update("csat_config", string(encoded)).Error
}

// AnalyzeTemplate analyzes a CSAT template message for quality.
// Placeholder implementation — real WhatsApp template analysis requires Captain AI integration.
// Reference: Chatwoot InboxCsatTemplatesController#analyze (captain_enabled check)
func (s *CsatTemplateService) AnalyzeTemplate(ctx context.Context, inboxID uint, req AnalyzeCsatTemplateRequest) (*CsatTemplateAnalysisResult, error) {
	if err := pkgvalidator.ValidateStruct(req); err != nil {
		return nil, err
	}

	// Placeholder analysis logic — real implementation would use Captain AI
	// to validate template against WhatsApp Business API requirements.
	result := &CsatTemplateAnalysisResult{
		Message:     req.Message,
		Quality:     "good",
		IsApproved:  true,
		Suggestions: []string{},
	}

	// Basic heuristic checks
	if len(req.Message) < 10 {
		result.Quality = "poor"
		result.IsApproved = false
		result.Suggestions = append(result.Suggestions, "Message is too short for a CSAT survey template")
	}
	if len(req.Message) > 500 {
		result.Quality = "needs_improvement"
		result.Suggestions = append(result.Suggestions, "Message may be too long for WhatsApp template approval")
	}

	applogger.L().Infof("CSAT template analyzed for inbox %d, quality=%s", inboxID, result.Quality)
	return result, nil
}

type defaultCsatTemplateProvider struct{}

func (defaultCsatTemplateProvider) CreateTemplate(ctx context.Context, inbox *model.Inbox, template *model.CsatTemplate, req CreateCsatTemplateRequest) (*CsatTemplateProviderResult, error) {
	language := req.Language
	if language == "" {
		language = "en"
	}
	baseName := csatTemplateName(inbox.ID)
	if isTwilioWhatsAppInbox(inbox) {
		return &CsatTemplateProviderResult{
			TemplateExists: true,
			Status:         "PENDING",
			FriendlyName:   baseName,
			ContentSID:     fmt.Sprintf("HXCSAT%08d", template.ID),
			ApprovalSID:    fmt.Sprintf("HACSAT%08d", template.ID),
			Language:       language,
		}, nil
	}
	return &CsatTemplateProviderResult{
		TemplateExists: true,
		Status:         "PENDING",
		TemplateName:   baseName,
		TemplateID:     fmt.Sprintf("csat_template_%d", template.ID),
		Language:       language,
	}, nil
}

func (defaultCsatTemplateProvider) GetTemplateStatus(ctx context.Context, inbox *model.Inbox, template *model.CsatTemplate) (*CsatTemplateProviderResult, error) {
	if template == nil {
		return &CsatTemplateProviderResult{TemplateExists: false}, nil
	}
	result := &CsatTemplateProviderResult{TemplateExists: true, Status: providerStatusOrPending(template.Status), Language: "en"}
	var config struct {
		Template map[string]any `json:"template"`
	}
	if inbox != nil && strings.TrimSpace(inbox.CsatConfig) != "" {
		_ = json.Unmarshal([]byte(inbox.CsatConfig), &config)
	}
	if len(config.Template) == 0 {
		return result, nil
	}
	result.Status = firstConfigString(config.Template, "status", result.Status)
	result.Language = firstConfigString(config.Template, "language", result.Language)
	result.TemplateName = firstConfigString(config.Template, "name", "")
	result.TemplateID = firstConfigString(config.Template, "template_id", "")
	result.FriendlyName = firstConfigString(config.Template, "friendly_name", "")
	result.ContentSID = firstConfigString(config.Template, "content_sid", "")
	result.ApprovalSID = firstConfigString(config.Template, "approval_sid", "")
	return result, nil
}

func providerStatusOrPending(status string) string {
	if strings.TrimSpace(status) == "" {
		return "PENDING"
	}
	return status
}

func csatTemplateName(inboxID uint) string {
	return fmt.Sprintf("csat_survey_%d", inboxID)
}

func isTwilioWhatsAppInbox(inbox *model.Inbox) bool {
	if inbox == nil {
		return false
	}
	channelType := strings.ToLower(inbox.ChannelType)
	return strings.Contains(channelType, "twilio") && (strings.Contains(channelType, "whatsapp") || strings.Contains(strings.ToLower(inbox.ChannelConfig), "whatsapp"))
}

func firstConfigString(config map[string]any, key, fallback string) string {
	if raw, ok := config[key]; ok {
		if value := strings.TrimSpace(fmt.Sprintf("%v", raw)); value != "" {
			return value
		}
	}
	return fallback
}