package mailq

import (
	"errors"
	"fmt"
	"sort"
)

type QEntrySortConfig struct {
	attributes []qEntryAttributeSortConfig
}

type qEntryAttributeSortConfig struct {
	attribute string
	order     string
}

func NewSortConfig() QEntrySortConfig {
	return QEntrySortConfig{}
}

func isQEntryAttribute(attributeName string) bool {
	var isValidAttribute bool
	switch attributeName {
	case "Id", "Status", "Date", "Size", "Sender", "Recipients", "Reason":
		isValidAttribute = true
	default:
		isValidAttribute = false
	}
	return isValidAttribute
}

func (c QEntrySortConfig) By(attributeName string, order string) (QEntrySortConfig, error) {
	if !isQEntryAttribute(attributeName) {
		return c, errors.New(fmt.Sprintf("Invalid sort attribute: '%s' given!", attributeName))
	}
	if order != "ASC" && order != "DESC" {
		return c, errors.New(fmt.Sprintf("Invalid sort order '%s' given!", order))
	}
	newAttributeConfig := qEntryAttributeSortConfig{attribute: attributeName, order: order}
	c.attributes = append(c.attributes, newAttributeConfig)
	return c, nil
}

func (queue MailQ) Sort(config QEntrySortConfig) {
	if len(config.attributes) == 0 {
		return
	}
	sort.Slice(queue.Entries, func(a int, b int) bool {
		for _, sortBy := range config.attributes {
			var cmp bool
			var skip bool
			// Not sure if these are necessary yet
			cmp = false
			skip = false
			switch sortBy.attribute {
			case "Id":
				if queue.Entries[a].Id == queue.Entries[b].Id {
					skip = true
				}
				cmp = queue.Entries[a].Id < queue.Entries[b].Id
			case "Status":
				if queue.Entries[a].Status == queue.Entries[b].Status {
					skip = true
				}
				cmp = queue.Entries[a].Status < queue.Entries[b].Status
			case "Date":
				if queue.Entries[a].Date.Equal(queue.Entries[b].Date) {
					skip = true
				}
				cmp = queue.Entries[a].Date.Before(queue.Entries[b].Date)
			case "Size":
				if queue.Entries[a].Size == queue.Entries[b].Size {
					skip = true
				}
				cmp = queue.Entries[a].Size < queue.Entries[b].Size
			case "Sender":
				if queue.Entries[a].Sender == queue.Entries[b].Sender {
					skip = true
				}
				cmp = queue.Entries[a].Sender < queue.Entries[b].Sender
			case "Recipients":
				if len(queue.Entries[a].Recipients) == len(queue.Entries[b].Recipients) {
					skip = true
				}
				cmp = len(queue.Entries[a].Recipients) < len(queue.Entries[b].Recipients)
			case "Reason":
				if queue.Entries[a].Reason == queue.Entries[b].Reason {
					skip = true
				}
				cmp = queue.Entries[a].Reason < queue.Entries[b].Reason
			default:
				// TODO: Handle this error case?
			}
			if skip == true {
				continue
			} else {
				if sortBy.order == "ASC" {
					return cmp
				} else if sortBy.order == "DESC" {
					return !cmp
				}
			}
		}
		return false
	})
}