package service

import (
	"context"
	"fmt"

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

// CaptainPreferenceService implements business logic for CaptainPreference operations.
// Reference: Chatwoot enterprise/app/controllers/api/v1/captain/preferences_controller.rb
type CaptainPreferenceService struct {
	repo *repository.CaptainPreferenceRepo
}

func NewCaptainPreferenceService(repo *repository.CaptainPreferenceRepo) *CaptainPreferenceService {
	return &CaptainPreferenceService{repo: repo}
}

// --- Request DTOs ---

// CreatePreferenceRequest is the DTO for creating a preference.
// Reference: Chatwoot enterprise/app/models/captain/preference.rb
type CreatePreferenceRequest struct {
	Tone               string `json:"tone" validate:"omitempty,oneof=professional casual friendly formal"`
	Language           string `json:"language" validate:"omitempty,min=1,max=10"`
	ResponseGuidelines string `json:"response_guidelines" validate:"omitempty,max=2000"`
	AutoLabelEnabled   bool   `json:"auto_label_enabled"`
	AutoFollowUpEnabled bool  `json:"auto_follow_up_enabled"`
	AutoReplyEnabled   bool   `json:"auto_reply_enabled"`
	MaxResponseLength  int    `json:"max_response_length" validate:"omitempty,min=50,max=5000"`
	CustomPromptSuffix string `json:"custom_prompt_suffix" validate:"omitempty,max=1000"`
}

// UpdatePreferenceRequest is the DTO for updating a preference.
// Reference: Chatwoot enterprise/app/models/captain/preference.rb
type UpdatePreferenceRequest struct {
	Tone               string `json:"tone,omitempty" validate:"omitempty,oneof=professional casual friendly formal"`
	Language           string `json:"language,omitempty" validate:"omitempty,min=1,max=10"`
	ResponseGuidelines string `json:"response_guidelines,omitempty" validate:"omitempty,max=2000"`
	AutoLabelEnabled   *bool  `json:"auto_label_enabled,omitempty"`
	AutoFollowUpEnabled *bool `json:"auto_follow_up_enabled,omitempty"`
	AutoReplyEnabled   *bool  `json:"auto_reply_enabled,omitempty"`
	MaxResponseLength  *int   `json:"max_response_length,omitempty" validate:"omitempty,min=50,max=5000"`
	CustomPromptSuffix string `json:"custom_prompt_suffix,omitempty" validate:"omitempty,max=1000"`
}

// --- Business logic ---

// validTones are the allowed tone values for captain preferences.
// Reference: Chatwoot enterprise/app/models/captain/preference.rb TONES
var validTones = []string{"professional", "casual", "friendly", "formal"}

// isValidTone checks if a tone value is valid.
func isValidTone(tone string) bool {
	for _, t := range validTones {
		if t == tone {
			return true
		}
	}
	return false
}

// Create creates a new preference for an account.
func (s *CaptainPreferenceService) Create(ctx context.Context, accountID uint, req *CreatePreferenceRequest) (*model.CaptainPreference, error) {
	// Validate request
	if err := pkgvalidator.ValidateStruct(req); err != nil {
		return nil, fmt.Errorf("validation error: %w", err)
	}

	// Check if preference already exists for this account
	existing, err := s.repo.GetByAccountID(ctx, accountID)
	if err == nil && existing != nil {
		return nil, fmt.Errorf("preference already exists for account %d", accountID)
	}

	pref := &model.CaptainPreference{
		AccountID:          accountID,
		Tone:               req.Tone,
		Language:           req.Language,
		ResponseGuidelines: req.ResponseGuidelines,
		AutoLabelEnabled:   req.AutoLabelEnabled,
		AutoFollowUpEnabled: req.AutoFollowUpEnabled,
		AutoReplyEnabled:   req.AutoReplyEnabled,
		MaxResponseLength:  req.MaxResponseLength,
		CustomPromptSuffix: req.CustomPromptSuffix,
	}

	// Apply defaults
	if pref.Tone == "" {
		pref.Tone = "professional"
	}
	if pref.Language == "" {
		pref.Language = "en"
	}
	if pref.MaxResponseLength == 0 {
		pref.MaxResponseLength = 500
	}

	if err := s.repo.Create(ctx, pref); err != nil {
		applogger.L().Errorf("Create captain preference: %v", err)
		return nil, fmt.Errorf("create preference: %w", err)
	}

	return pref, nil
}

// Get retrieves the preference for an account.
func (s *CaptainPreferenceService) Get(ctx context.Context, accountID uint) (*model.CaptainPreference, error) {
	pref, err := s.repo.GetByAccountID(ctx, accountID)
	if err != nil {
		return nil, fmt.Errorf("preference not found for account %d: %w", accountID, err)
	}
	return pref, nil
}

// Update updates the preference for an account.
func (s *CaptainPreferenceService) Update(ctx context.Context, accountID uint, req *UpdatePreferenceRequest) (*model.CaptainPreference, error) {
	// Validate request
	if err := pkgvalidator.ValidateStruct(req); err != nil {
		return nil, fmt.Errorf("validation error: %w", err)
	}

	pref, err := s.repo.GetByAccountID(ctx, accountID)
	if err != nil {
		return nil, fmt.Errorf("preference not found for account %d: %w", accountID, err)
	}

	// Apply partial updates
	if req.Tone != "" {
		pref.Tone = req.Tone
	}
	if req.Language != "" {
		pref.Language = req.Language
	}
	if req.ResponseGuidelines != "" {
		pref.ResponseGuidelines = req.ResponseGuidelines
	}
	if req.AutoLabelEnabled != nil {
		pref.AutoLabelEnabled = *req.AutoLabelEnabled
	}
	if req.AutoFollowUpEnabled != nil {
		pref.AutoFollowUpEnabled = *req.AutoFollowUpEnabled
	}
	if req.AutoReplyEnabled != nil {
		pref.AutoReplyEnabled = *req.AutoReplyEnabled
	}
	if req.MaxResponseLength != nil {
		pref.MaxResponseLength = *req.MaxResponseLength
	}
	if req.CustomPromptSuffix != "" {
		pref.CustomPromptSuffix = req.CustomPromptSuffix
	}

	if err := s.repo.Update(ctx, pref); err != nil {
		applogger.L().Errorf("Update captain preference: %v", err)
		return nil, fmt.Errorf("update preference: %w", err)
	}

	return pref, nil
}

// Delete removes the preference for an account.
func (s *CaptainPreferenceService) Delete(ctx context.Context, accountID uint) error {
	if err := s.repo.Delete(ctx, accountID); err != nil {
		applogger.L().Errorf("Delete captain preference: %v", err)
		return fmt.Errorf("delete preference: %w", err)
	}
	return nil
}