package productDescriptionService

import (
	"context"
	"encoding/xml"
	"fmt"
	"io"
	"slices"
	"strings"

	"git.ma-al.com/goc_daniel/b2b/app/db"
	"git.ma-al.com/goc_daniel/b2b/app/model"
	"git.ma-al.com/goc_daniel/b2b/app/service/langsService"
	"git.ma-al.com/goc_daniel/b2b/app/utils/responseErrors"
	"gorm.io/gorm"

	"github.com/openai/openai-go/v3"
	"github.com/openai/openai-go/v3/option"
	"github.com/openai/openai-go/v3/responses"
)

type ProductDescriptionService struct {
	db     *gorm.DB
	client openai.Client
}

func New() *ProductDescriptionService {
	return &ProductDescriptionService{
		db:     db.Get(),
		client: openai.NewClient(option.WithAPIKey("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")),
	}
}

func isValidXHTML(s string) bool {
	decoder := xml.NewDecoder(strings.NewReader(s))
	hasStartTag := false

	for {
		tok, err := decoder.Token()
		if err != nil {
			if err == io.EOF {
				return hasStartTag
			}
			return false
		}

		if _, ok := tok.(xml.StartElement); ok {
			hasStartTag = true
		}
	}
}

// We assume that any user has access to all product descriptions
func (s *ProductDescriptionService) GetProductDescription(userID uint, productID uint, productShopID uint, productLangID uint) (*model.ProductDescription, error) {
	var ProductDescription model.ProductDescription

	err := s.db.
		Table("ps_product_lang").
		Where("id_product = ? AND id_shop = ? AND id_lang = ?", productID, productShopID, productLangID).
		First(&ProductDescription).Error
	if err != nil {
		return nil, fmt.Errorf("database error: %w", err)
	}

	return &ProductDescription, nil
}

// Updates relevant fields with the "updates" map
func (s *ProductDescriptionService) SaveProductDescription(userID uint, productID uint, productShopID uint, productLangID uint, updates map[string]string) error {
	// only some fields can be affected
	allowedFields := []string{"description", "description_short", "meta_description", "meta_title", "name", "available_now", "available_later", "usage"}
	for key := range updates {
		if !slices.Contains(allowedFields, key) {
			return responseErrors.ErrBadField
		}
	}

	// check that fields description, description_short and usage, if they exist, have a valid html format
	mustBeHTML := []string{"description", "description_short", "usage"}
	for i := 0; i < len(mustBeHTML); i++ {
		if text, exists := updates[mustBeHTML[i]]; exists {
			if !isValidXHTML(text) {
				return responseErrors.ErrInvalidHTML
			}
		}
	}

	record := model.ProductDescription{
		ProductID: productID,
		ShopID:    productShopID,
		LangID:    productLangID,
	}

	err := s.db.
		Table("ps_product_lang").
		Where("id_product = ? AND id_shop = ? AND id_lang = ?", productID, productShopID, productLangID).
		FirstOrCreate(&record).Error
	if err != nil {
		return fmt.Errorf("database error: %w", err)
	}

	if len(updates) == 0 {
		return nil
	}
	updatesIface := make(map[string]interface{}, len(updates))
	for k, v := range updates {
		updatesIface[k] = v
	}

	err = s.db.
		Table("ps_product_lang").
		Where("id_product = ? AND id_shop = ? AND id_lang = ?", productID, productShopID, productLangID).
		Updates(updatesIface).Error
	if err != nil {
		return fmt.Errorf("database error: %w", err)
	}

	return nil
}

// Updates relevant fields with the "updates" map
func (s *ProductDescriptionService) TranslateProductDescription(userID uint, productID uint, productShopID uint, productFromLangID uint, productToLangID uint) (*model.ProductDescription, error) {
	var ProductDescription model.ProductDescription

	err := s.db.
		Table("ps_product_lang").
		Where("id_product = ? AND id_shop = ? AND id_lang = ?", productID, productShopID, productFromLangID).
		First(&ProductDescription).Error
	if err != nil {
		return nil, fmt.Errorf("database error: %w", err)
	}

	// we translate all changeable fields, and we keep the exact same HTML structure in relevant fields.
	lang, err := langsService.LangSrv.GetLanguageById(productToLangID)
	if err != nil {
		return nil, err
	}

	request := "Translate to " + lang.ISOCode + " without changing the html structure. You must only translate text visible on website.\n\n"
	request += "\n"
	request += "<translation_of_product_description>"
	request += ProductDescription.Description
	request += "</translation_of_product_description>"
	request += "\n"
	request += "Remember: translate to " + lang.ISOCode + " without changing the html structure. You must only translate text visible on website."
	request += "\n"
	request += "<translation_of_product_short_description>"
	request += ProductDescription.DescriptionShort
	request += "</translation_of_product_short_description>"
	request += "\n"
	request += "Remember: translate to " + lang.ISOCode + " without changing the html structure. You must only translate text visible on website."
	request += "\n"
	request += "<translation_of_product_meta_description>"
	request += ProductDescription.MetaDescription
	request += "</translation_of_product_meta_description>"
	request += "\n"
	request += "Remember: translate to " + lang.ISOCode + " without changing the html structure. You must only translate text visible on website."
	request += "\n"
	request += "<translation_of_product_meta_title>"
	request += ProductDescription.MetaTitle
	request += "</translation_of_product_meta_title>"
	request += "\n"
	request += "Remember: translate to " + lang.ISOCode + " without changing the html structure. You must only translate text visible on website."
	request += "\n"
	request += "<translation_of_product_name>"
	request += ProductDescription.Name
	request += "</translation_of_product_name>"
	request += "\n"
	request += "Remember: translate to " + lang.ISOCode + " without changing the html structure. You must only translate text visible on website."
	request += "\n"
	request += "<translation_of_display_text_available_now>"
	request += ProductDescription.AvailableNow
	request += "</translation_of_display_text_available_now>"
	request += "\n"
	request += "Remember: translate to " + lang.ISOCode + " without changing the html structure. You must only translate text visible on website."
	request += "\n"
	request += "<translation_of_display_text_available_later>"
	request += ProductDescription.AvailableLater
	request += "</translation_of_display_text_available_later>"
	request += "\n"
	request += "Remember: translate to " + lang.ISOCode + " without changing the html structure. You must only translate text visible on website."
	request += "\n"
	request += "<translation_of_product_usage>"
	request += ProductDescription.Usage
	request += "</translation_of_product_usage>"

	openai_response, err := s.client.Responses.New(context.Background(), responses.ResponseNewParams{
		Input: responses.ResponseNewParamsInputUnion{OfString: openai.String(request)},
		Model: openai.ChatModelGPT4_1Mini,
		// Model: openai.ChatModelGPT4_1Nano,
	})
	if openai_response.Status != "completed" {
		return nil, responseErrors.ErrOpenAIResponseFail
	}
	output := openai_response.OutputText()

	// for debugging purposes
	// fi, err := os.ReadFile("/home/daniel/coding/work/b2b/app/service/productDescriptionService/test.txt") // just pass the file name
	// output := string(fi)

	success, match := GetStringInBetween(output, "<translation_of_product_description>", "</translation_of_product_description>")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.Description = match

	success, match = GetStringInBetween(output, "<translation_of_product_short_description>", "</translation_of_product_short_description>")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.DescriptionShort = match

	success, match = GetStringInBetween(output, "<translation_of_product_meta_description>", "</translation_of_product_meta_description>")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.MetaDescription = match

	success, match = GetStringInBetween(output, "<translation_of_product_meta_title>", "</translation_of_product_meta_title>")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.MetaTitle = match

	success, match = GetStringInBetween(output, "<translation_of_product_name>", "</translation_of_product_name>")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.Name = match

	success, match = GetStringInBetween(output, "<translation_of_display_text_available_now>", "</translation_of_display_text_available_now>")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.AvailableNow = match

	success, match = GetStringInBetween(output, "<translation_of_display_text_available_later>", "</translation_of_display_text_available_later>")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.AvailableLater = match

	success, match = GetStringInBetween(output, "<translation_of_product_usage>", "</translation_of_product_usage>")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.Usage = match

	return &ProductDescription, nil
}

// GetStringInBetween returns empty string if no start or end string found
func GetStringInBetween(str string, start string, end string) (success bool, result string) {
	s := strings.Index(str, start)
	if s == -1 {
		return false, ""
	}
	s += len(start)
	e := strings.Index(str[s:], end)
	if e == -1 {
		return false, ""
	}

	return true, str[s : s+e]
}