package fetch

import (
	"context"
	"fmt"
	"time"

	"github.com/mmcdole/gofeed"

	"gitea.konchin.com/service/stonks/internal/config"
)

func init() {
	Register("rss", newRSSFetcher)
}

// rssParams is the plugin-specific config for the rss fetcher.
type rssParams struct {
	Feeds []string `yaml:"feeds"`
	// MaxItemsPerFeed caps how many of the newest entries are kept per feed.
	// Defaults to 10.
	MaxItemsPerFeed int `yaml:"max_items_per_feed"`
	// MaxAgeHours drops entries older than this many hours. Defaults to 48.
	// Feeds with entries lacking a published date are kept regardless.
	MaxAgeHours int `yaml:"max_age_hours"`
}

// rssFetcher pulls general market news headlines from a configured list of
// RSS feeds. Free, no API key.
type rssFetcher struct {
	feeds           []string
	maxItemsPerFeed int
	maxAge          time.Duration
	parser          *gofeed.Parser
}

func newRSSFetcher(cfg config.PluginConfig) (Fetcher, error) {
	params := rssParams{
		MaxItemsPerFeed: 10,
		MaxAgeHours:     48,
	}
	if err := cfg.DecodeParams(&params); err != nil {
		return nil, err
	}
	if len(params.Feeds) == 0 {
		return nil, fmt.Errorf("rss: at least one feed URL must be configured")
	}

	return &rssFetcher{
		feeds:           params.Feeds,
		maxItemsPerFeed: params.MaxItemsPerFeed,
		maxAge:          time.Duration(params.MaxAgeHours) * time.Hour,
		parser:          gofeed.NewParser(),
	}, nil
}

func (f *rssFetcher) Name() string { return "rss" }

func (f *rssFetcher) Fetch(ctx context.Context, _ config.Targets) (Result, error) {
	var result Result
	var errs []error
	cutoff := time.Now().Add(-f.maxAge)

	for _, feedURL := range f.feeds {
		feed, err := f.parser.ParseURLWithContext(feedURL, ctx)
		if err != nil {
			errs = append(errs, fmt.Errorf("rss %s: %w", feedURL, err))
			continue
		}

		count := 0
		for _, item := range feed.Items {
			if count >= f.maxItemsPerFeed {
				break
			}
			if item.PublishedParsed != nil && item.PublishedParsed.Before(cutoff) {
				continue
			}

			var published time.Time
			if item.PublishedParsed != nil {
				published = *item.PublishedParsed
			}

			result.News = append(result.News, NewsItem{
				Title:     item.Title,
				Source:    feed.Title,
				URL:       item.Link,
				Published: published,
				Summary:   item.Description,
			})
			count++
		}
	}

	return result, joinErrs(errs)
}