package routes

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

	"git.artlef.fr/bibliomane/internal/appcontext"
	"git.artlef.fr/bibliomane/internal/dto"
	"git.artlef.fr/bibliomane/internal/model"
	"git.artlef.fr/bibliomane/internal/myvalidator"
	"github.com/gin-gonic/gin"
	"github.com/go-playground/validator/v10"
	"gorm.io/gorm"
)

func PutUserBookHandler(ac appcontext.AppContext) {
	bookId64, err := strconv.ParseUint(ac.C.Param("id"), 10, 64)
	bookId := uint(bookId64)
	if err != nil {
		ac.C.JSON(http.StatusBadRequest, gin.H{"error": err})
		return
	}
	err = myvalidator.ValidateId(ac.Db, bookId, &model.Book{})
	if err != nil {
		myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
		return
	}

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

	var userBookPut dto.UserBookPutUpdate
	err = ac.C.ShouldBindJSON(&userBookPut)
	if err != nil {
		myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
		return
	}
	userbook, err := fetchOrCreateUserBook(ac, bookId, &user)
	if err != nil {
		myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
		return
	}

	if userBookPut.Read != nil {
		err = updateReadStatus(&userbook, &userBookPut)
		if err != nil {
			myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
			return
		}
	}
	if userBookPut.WantRead != nil {
		userbook.WantRead = *userBookPut.WantRead
	}
	if userBookPut.StartDate != nil {
		d, err := parseDate(*userBookPut.StartDate)
		if err != nil {
			myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
			return
		}
		userbook.StartReadDate = d
	}
	if userBookPut.Rating != nil {
		err = validateRating(*userBookPut.Rating)
		if err != nil {
			myvalidator.ReturnErrorsAsJsonResponse(&ac, err)
			return
		}
		updateRating(&userbook, &userBookPut)
	}
	if userBookPut.Review != nil {
		userbook.Review = *userBookPut.Review
	}
	ac.Db.Save(&userbook)
	ac.C.String(http.StatusOK, "Success")
}

func validateRating(rating int) error {
	//struct used for validation
	var ratingStruct struct {
		Rating int `validate:"gte=0,lte=10"`
	}
	ratingStruct.Rating = rating
	validate := validator.New()
	return validate.Struct(ratingStruct)
}

func updateReadStatus(userbook *model.UserBook, userBookPut *dto.UserBookPutUpdate) error {
	userbook.Read = *userBookPut.Read

	if userBookPut.EndDate != nil && *userBookPut.EndDate != "" {
		d, err := parseDate(*userBookPut.EndDate)
		if err != nil {
			return err
		}
		userbook.EndReadDate = d
	}

	//remove the book from "wanted" list when it is marked as read.
	if userbook.Read {
		userbook.WantRead = false
	}

	//clear the date when unread
	if !userbook.Read {
		userbook.EndReadDate = nil
	}
	return nil
}

func updateRating(userbook *model.UserBook, userBookPut *dto.UserBookPutUpdate) {
	userbook.Rating = *userBookPut.Rating

	//if rated, set to "read" (a rating = 0 means unrated)
	if userbook.Rating > 0 {
		userbook.Read = true
		//if set to read, remove want read
		userbook.WantRead = false
	}
}

func parseDate(dateToParse string) (*time.Time, error) {
	//string equal to "null" to unset value
	if dateToParse == "null" {
		return nil, nil
	} else {
		startDate, err := time.Parse(time.DateOnly, dateToParse)
		return &startDate, err
	}
}

func fetchOrCreateUserBook(ac appcontext.AppContext, bookId uint, user *model.User) (model.UserBook, error) {
	var userbook model.UserBook
	res := ac.Db.Where("user_id = ? AND book_id = ?", user.ID, bookId).First(&userbook)
	err := res.Error
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			userbook = createUserBook(bookId, user)
			err = ac.Db.Save(&userbook).Error
			if err != nil {
				return userbook, err
			}
			return userbook, nil
		} else {
			return userbook, err
		}
	} else {
		return userbook, nil
	}
}

func createUserBook(bookId uint, user *model.User) model.UserBook {
	return model.UserBook{
		UserID:   user.ID,
		BookID:   bookId,
		Read:     false,
		WantRead: false,
		Rating:   0,
	}
}