package productDescriptionService

import (
	"context"
	"encoding/xml"
	"fmt"
	"io"
	"net/http"
	"slices"
	"strings"
	"time"

	"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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"),
			option.WithHTTPClient(&http.Client{Timeout: 300 * time.Second})),
	}
}

// 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.ErrInvalidXHTML
			}
		}
	}

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

	request = cleanForPrompt(request)

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

	success, resolution := resolveResponse(ProductDescription.Description, output, "translation_of_product_description")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.Description = resolution

	success, resolution = resolveResponse(ProductDescription.DescriptionShort, output, "translation_of_product_short_description")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.DescriptionShort = resolution

	success, resolution = resolveResponse(ProductDescription.MetaDescription, output, "translation_of_product_meta_description")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.MetaDescription = resolution

	success, resolution = resolveResponse(ProductDescription.MetaTitle, output, "translation_of_product_meta_title")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.MetaTitle = resolution

	success, resolution = resolveResponse(ProductDescription.Name, output, "translation_of_product_name")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.Name = resolution

	success, resolution = resolveResponse(ProductDescription.AvailableNow, output, "translation_of_display_text_available_now")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.AvailableNow = resolution

	success, resolution = resolveResponse(ProductDescription.AvailableLater, output, "translation_of_display_text_available_later")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.AvailableLater = resolution

	success, resolution = resolveResponse(ProductDescription.Usage, output, "translation_of_product_usage")
	if !success {
		return nil, responseErrors.ErrOpenAIBadOutput
	}
	ProductDescription.Usage = resolution

	return &ProductDescription, nil
}

// isValidXHTML checks if the string obeys the XHTML format
func isValidXHTML(s string) bool {
	r := strings.NewReader(s)
	d := xml.NewDecoder(r)

	// Configure the decoder for HTML; leave off strict and autoclose for XHTML
	d.Strict = true
	d.AutoClose = xml.HTMLAutoClose
	d.Entity = xml.HTMLEntity
	for {
		_, err := d.Token()
		switch err {
		case io.EOF:
			return true // We're done, it's valid!
		case nil:
		default:
			return false // Oops, something wasn't right
		}
	}
}

func cleanForPrompt(s string) string {
	r := strings.NewReader(s)
	d := xml.NewDecoder(r)

	prompt := ""

	// Configure the decoder for HTML; leave off strict and autoclose for XHTML
	d.Strict = true
	d.AutoClose = xml.HTMLAutoClose
	d.Entity = xml.HTMLEntity
	for {
		token, err := d.Token()
		if err == io.EOF {
			break
		}

		switch v := token.(type) {
		case xml.StartElement:
			prompt += "<" + AttrName(v.Name)

			for _, attr := range v.Attr {
				if v.Name.Local == "img" && attr.Name.Local == "alt" {
					prompt += fmt.Sprintf(` %s="%s"`, AttrName(attr.Name), attr.Value)
				}
			}

			prompt += ">"
		case xml.EndElement:
			prompt += "</" + AttrName(v.Name) + ">"
		case xml.CharData:
			prompt += string(v)
		case xml.Comment:
		case xml.ProcInst:
		case xml.Directive:
		}
	}

	return prompt
}

func resolveResponse(original string, response string, key string) (bool, string) {
	success, match := GetStringInBetween(response, "<"+key+">", "</"+key+">")
	if !success || !isValidXHTML(match) {
		return false, ""
	}

	success, resolution := RebuildFromResponse("<"+key+">"+original+"</"+key+">", "<"+key+">"+match+"</"+key+">")
	if !success {
		return false, ""
	}

	return true, resolution[2+len(key) : len(resolution)-3-len(key)]
}

// 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]
}

// Rebuilds HTML using the original HTML as a template and the response as a source
// Assumes that both original and response have the exact same XML structure
func RebuildFromResponse(s_original string, s_response string) (bool, string) {

	r_original := strings.NewReader(s_original)
	d_original := xml.NewDecoder(r_original)

	r_response := strings.NewReader(s_response)
	d_response := xml.NewDecoder(r_response)

	result := ""

	// Configure the decoder for HTML; leave off strict and autoclose for XHTML
	d_original.Strict = true
	d_original.AutoClose = xml.HTMLAutoClose
	d_original.Entity = xml.HTMLEntity

	d_response.Strict = true
	d_response.AutoClose = xml.HTMLAutoClose
	d_response.Entity = xml.HTMLEntity

	token_original, err_original := d_original.Token()
	token_response, err_response := d_response.Token()

	for {
		// err_original can only be EOF or nil.
		if err_original != nil || err_response != nil {
			if err_original != err_response {
				return false, ""
			}
			return true, result
		}

		switch v_original := token_original.(type) {
		case xml.StartElement:
			switch v_response := token_response.(type) {
			case xml.StartElement:
				if v_original.Name.Space != v_response.Name.Space || v_original.Name.Local != v_response.Name.Local {
					return false, ""
				}

				result += "<" + AttrName(v_original.Name)

				for _, attr := range v_original.Attr {
					if v_original.Name.Local != "img" || attr.Name.Local != "alt" {
						result += fmt.Sprintf(` %s="%s"`, AttrName(attr.Name), attr.Value)
					}
				}

				for _, attr := range v_response.Attr {
					if v_response.Name.Local == "img" && attr.Name.Local == "alt" {
						result += fmt.Sprintf(` %s="%s"`, AttrName(attr.Name), attr.Value)
					}
				}
				result += ">"

			case xml.CharData:
				result += string(v_response)
				token_response, err_response = d_response.Token()
				continue

			default:
				return false, ""
			}

		case xml.EndElement:
			switch v_response := token_response.(type) {
			case xml.EndElement:
				if v_original.Name.Space != v_response.Name.Space || v_original.Name.Local != v_response.Name.Local {
					return false, ""
				}

				if v_original.Name.Local != "img" {
					result += "</" + AttrName(v_original.Name) + ">"
				}

			case xml.CharData:
				result += string(v_response)
				token_response, err_response = d_response.Token()
				continue

			default:
				return false, ""
			}

		case xml.CharData:
			switch v_response := token_response.(type) {
			case xml.CharData:
				result += string(v_response)

			case xml.StartElement:
				result += string(v_original)
				token_original, err_original = d_original.Token()
				continue

			case xml.EndElement:
				result += string(v_original)
				token_original, err_original = d_original.Token()
				continue

			default:
				return false, ""
			}

		case xml.Comment:
			result += "<!--" + string(v_original) + "-->"
			token_original, err_original = d_original.Token()
			continue

		case xml.ProcInst:
			if len(v_original.Inst) == 0 {
				result += "<?" + v_original.Target + "?>"
			} else {
				result += "<?" + v_original.Target + " " + string(v_original.Inst) + "?>"
			}
			token_original, err_original = d_original.Token()
			continue

		case xml.Directive:
			result += "<!" + string(v_original) + ">"
			token_original, err_original = d_original.Token()
			continue
		}

		token_original, err_original = d_original.Token()
		token_response, err_response = d_response.Token()
	}
}

func AttrName(name xml.Name) string {
	if name.Space == "" {
		return name.Local
	} else {
		return name.Space + ":" + name.Local
	}
}