package utils

import (
	"errors"
	"strconv"

	"github.com/gofiber/fiber/v2"
)

type OffsetPaginationError struct {
	Page     int
	Pages    int
	NextPage int
	LastPage int
}

func (p *OffsetPaginationError) Error() string {
	return "Not an error, just for offsetbased pagination."
}

func NewOffsetPaginationError(page int, pages int) error {
	var nextPage int
	if page+1 <= pages {
		nextPage = page + 1
	} else {
		nextPage = -1
	}

	return &OffsetPaginationError{Page: page, Pages: pages, NextPage: nextPage, LastPage: page - 1}
}

type KeysetPaginationError struct {
	Key         int
	NextKey     int
	PreviousKey int
}

func (p *KeysetPaginationError) Error() string {
	return "Not an error, just for Keysetbased pagination."
}

func NewKeysetPaginationError(key int, next int, previous int) error {
	return &KeysetPaginationError{Key: key, NextKey: next, PreviousKey: previous}
}

func AddPaginationParams(c *fiber.Ctx) error {
	err := c.Next()
	if err != nil {

		var offset *OffsetPaginationError
		if errors.As(err, &offset) {
			c.Append("X-Page", strconv.Itoa(offset.Page))
			c.Append("X-Pages", strconv.Itoa(offset.Pages))
			c.Append("X-Next-Page", strconv.Itoa(offset.NextPage))
			c.Append("X-Last-Page", strconv.Itoa(offset.LastPage))
			return nil
		}

		var keyset *KeysetPaginationError
		if errors.As(err, &keyset) {
			c.Append("X-Key", strconv.Itoa(keyset.Key))
			c.Append("X-Previous-Key", strconv.Itoa(keyset.PreviousKey))
			c.Append("X-Next-Key", strconv.Itoa(keyset.NextKey))
			return nil
		}
	}
	return err
}