package routes

import (
	"errors"
	"net/http"
	"strconv"

	"git.artlef.fr/bibliomane/internal/appcontext"
	"git.artlef.fr/bibliomane/internal/dto"
	"git.artlef.fr/bibliomane/internal/i18nresource"
	"git.artlef.fr/bibliomane/internal/model"
	"git.artlef.fr/bibliomane/internal/myvalidator"
	"git.artlef.fr/bibliomane/internal/query"
	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

func PostCollectionChangePositionHandler(ac appcontext.AppContext) {
	collectionId, err := strconv.ParseUint(ac.C.Param("id"), 10, 64)
	if err != nil {
		ac.C.JSON(http.StatusBadRequest, gin.H{"error": err})
		return
	}

	user, err := ac.GetAuthenticatedUser()
	if err != nil {
		myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
		return
	}

	var collection model.Collection
	err = ac.Db.First(&collection, collectionId).Error
	if err != nil {
		myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
		return
	}

	if collection.UserID != user.ID {
		err := myvalidator.HttpError{
			StatusCode: http.StatusUnauthorized,
			Err:        errors.New(i18nresource.GetTranslatedMessage(&ac, "Unauthorized")),
		}
		myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
		return
	}

	var collectionBookPosition dto.CollectionItemPosition
	err = ac.C.ShouldBindJSON(&collectionBookPosition)
	if err != nil {
		myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
		return
	}

	var item model.CollectionItem
	err = ac.Db.First(&item, collectionBookPosition.ItemID).Error
	if err != nil {
		myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
		return
	}

	if collection.ID != item.CollectionID {
		err := myvalidator.HttpError{
			StatusCode: http.StatusInternalServerError,
			Err:        errors.New(i18nresource.GetTranslatedMessage(&ac, "ItemDoesNotBelongToCollection")),
		}
		myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
		return
	}
	count, err := query.FetchCollectionBooksCount(ac.Db, user.ID, item.CollectionID)
	if err != nil {
		myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
		return
	}
	newPosition := collectionBookPosition.Position
	if int64(newPosition) > count {
		newPosition = uint(count)
	}

	if item.Position == newPosition {
		//nothing to do
		ac.C.String(http.StatusOK, "Success")
		return
	}
	lowerPosition := item.Position + 1
	higherPosition := item.Position - 1
	operationToDo := ""
	if item.Position < newPosition {
		higherPosition = newPosition
		operationToDo = "position - 1"
	} else {
		lowerPosition = newPosition
		operationToDo = "position + 1"
	}

	q := ac.Db.Model(&model.CollectionItem{})
	q = q.Where("collection_id = ? AND position BETWEEN ? AND ?", collection.ID, lowerPosition, higherPosition)
	err = q.UpdateColumn("position", gorm.Expr(operationToDo)).Error
	if err != nil {
		myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
		return
	}

	item.Position = newPosition
	ac.Db.Save(&item)
	ac.C.String(http.StatusOK, "Success")
}