package core

import (
	"encoding/json"
	"fmt"
	"log"
)

type Item struct {
	Source  string `json:"source"`
	Id      string `json:"id"`
	Created int    `json:"created"`
	Active  bool   `json:"active"`
	Title   string `json:"title"`
	Author  string `json:"author"`
	Body    string `json:"body"`
	Link    string `json:"link"`
	Time    int    `json:"time"`
}

// Whether an item that no longer appears in a fetch can be deleted.
func (item Item) Deletable() bool {
	return !item.Active
}

func ItemsAreEqual(first Item, second Item) bool {
	// Hacky but easy to use
	return fmt.Sprintf("%#v", first) == fmt.Sprintf("%#v", second)
}

func FormatAsHeadline(item Item) string {
	title := item.Title
	if title == "" {
		title = item.Id
	}
	return title
}

func FormatAsJson(item Item) string {
	data, err := json.Marshal(item)
	if err != nil {
		log.Fatalf("error: failed to serialize %s/%s: %v", item.Source, item.Id, err)
	}
	return string(data)
}

func FormatAsShort(item Item) string {
	return fmt.Sprintf("%s/%s", item.Source, item.Id)
}

func FormatAs(format string) (func(item Item) string, error) {
	switch format {
	case "headlines":
		return FormatAsHeadline, nil
	case "json":
		return FormatAsJson, nil
	case "short":
		return FormatAsShort, nil
	default:
		return nil, fmt.Errorf("invalid format '%s'", format)
	}
}

var AvailableFormats = map[string]string{
	"headlines": "Only item titles",
	"json":      "Full item JSON",
	"short":     "Item source and id",
}