package backend

import (
	"fmt"
	"io"
	"os"

	"git.streifling.com/jason/atom"
)

type Feed struct{ *atom.Feed }

func GenerateAtomFeed(c *Config, db *DB) (*string, error) {
	feed := atom.NewFeed(c.Title)
	feed.ID = atom.NewID("urn:feed:1")
	feed.Subtitle = atom.NewText("text", c.Description)
	feed.AddLink(atom.NewLink(c.Link))

	feed.Generator = atom.NewGenerator("cpolis")
	feed.Generator.URI = "https://git.streifling.com/jason/cpolis"
	feed.Generator.Version = "0.13"

	articles, err := db.GetCertainArticles("published", true)
	if err != nil {
		return nil, fmt.Errorf("error getting published articles for RSS feed: %v", err)
	}

	for _, article := range articles {
		articleTitle, err := ConvertToPlain(article.Title)
		if err != nil {
			return nil, fmt.Errorf("error converting title to plain text for RSS feed: %v", err)
		}
		entry := atom.NewEntry(articleTitle)
		entry.ID = atom.NewID(fmt.Sprint("urn:entry:", article.ID))
		entry.Content = atom.NewContent(atom.OutOfLine, "text/hmtl", article.ContentLink)
		entry.Published = atom.NewDate(article.Created)

		linkID := entry.AddLink(atom.NewLink(article.BannerLink))
		entry.Links[linkID].Rel = "enclosure"
		entry.Links[linkID].Type = "image/webp"

		user, err := db.GetUser(c, article.AuthorID)
		if err != nil {
			return nil, fmt.Errorf("error getting user user info for RSS feed: %v", err)
		}
		entry.AddAuthor(atom.NewPerson(user.FirstName + " " + user.LastName))

		articleSummary, err := ConvertToPlain(article.Summary)
		if err != nil {
			return nil, fmt.Errorf("error converting description to plain text for RSS feed: %v", err)
		}
		if article.AutoGenerated {
			articleSummary = "auto generated"
		}
		entry.Summary = atom.NewText("text", articleSummary)

		tags, err := db.GetArticleTags(article.ID)
		if err != nil {
			return nil, fmt.Errorf("error getting tags for articles for RSS feed: %v", err)
		}
		for _, tag := range tags {
			entry.AddCategory(atom.NewCategory(tag.Name))
		}

		if article.IsInIssue || article.AutoGenerated {
			entry.AddCategory(atom.NewCategory(fmt.Sprint("Orient Express ", article.IssueID)))
		}
		if article.AutoGenerated {
			entry.AddCategory(atom.NewCategory("autogenerated"))
		}

		entry.Updated = atom.NewDate(article.Created)
		feed.AddEntry(entry)
	}

	if err = feed.Check(); err != nil {
		return nil, fmt.Errorf("error checking Atom feed: %v", err)
	}

	atom, err := feed.ToXML("UTF-8")
	if err != nil {
		return nil, fmt.Errorf("error converting RSS feed to XML: %v", err)
	}

	return &atom, nil
}

func SaveAtomFeed(filename string, feed *string) error {
	file, err := os.Create(filename)
	if err != nil {
		return fmt.Errorf("error creating file for Atom feed: %v", err)
	}
	defer file.Close()
	if err = file.Chmod(0644); err != nil {
		return fmt.Errorf("error setting permissions for Atom file: %v", err)
	}

	if _, err = io.WriteString(file, *feed); err != nil {
		return fmt.Errorf("error writing to Atom file: %v", err)
	}

	return nil
}