package nws

import (
	"context"
	"encoding/json"
	"strings"
	"time"

	"gitea.maximumdirect.net/ejr/feedkit/config"
	"gitea.maximumdirect.net/ejr/feedkit/event"
	fksources "gitea.maximumdirect.net/ejr/feedkit/sources"
	nwscommon "gitea.maximumdirect.net/ejr/weatherfeeder/internal/providers/nws"
	"gitea.maximumdirect.net/ejr/weatherfeeder/standards"
)

// WeatherStoriesSource polls an NWS weatherstories endpoint and emits a RAW weather story Event.
//
// Output schema:
//   - standards.SchemaRawNWSWeatherStoriesV1
type WeatherStoriesSource struct {
	http *fksources.HTTPSource
}

func NewWeatherStoriesSource(cfg config.SourceConfig) (*WeatherStoriesSource, error) {
	hs, err := fksources.NewHTTPSource(DriverWeatherStories, cfg, "application/geo+json, application/json")
	if err != nil {
		return nil, err
	}

	return &WeatherStoriesSource{http: hs}, nil
}

func (s *WeatherStoriesSource) Name() string { return s.http.Name }

func (s *WeatherStoriesSource) Kinds() []event.Kind {
	return []event.Kind{event.Kind(standards.KindWeatherStory)}
}

func (s *WeatherStoriesSource) Poll(ctx context.Context) ([]event.Event, error) {
	raw, meta, changed, err := s.fetchRaw(ctx)
	if err != nil {
		return nil, err
	}
	if !changed {
		return nil, nil
	}

	var effectiveAt *time.Time
	switch {
	case !meta.ParsedLatestUpdateTime.IsZero():
		t := meta.ParsedLatestUpdateTime.UTC()
		effectiveAt = &t
	case !meta.ParsedLatestStartTime.IsZero():
		t := meta.ParsedLatestStartTime.UTC()
		effectiveAt = &t
	}

	emittedAt := time.Now().UTC()
	eventID := fksources.DefaultEventID("", s.http.Name, effectiveAt, emittedAt)

	return fksources.SingleEvent(
		event.Kind(standards.KindWeatherStory),
		s.http.Name,
		standards.SchemaRawNWSWeatherStoriesV1,
		eventID,
		emittedAt,
		effectiveAt,
		raw,
	)
}

type weatherStoriesMeta struct {
	Stories []struct {
		StartTime  string `json:"startTime"`
		UpdateTime string `json:"updateTime"`
	} `json:"stories"`

	ParsedLatestUpdateTime time.Time `json:"-"`
	ParsedLatestStartTime  time.Time `json:"-"`
}

func (s *WeatherStoriesSource) fetchRaw(ctx context.Context) (json.RawMessage, weatherStoriesMeta, bool, error) {
	raw, changed, err := s.http.FetchJSONIfChanged(ctx)
	if err != nil {
		return nil, weatherStoriesMeta{}, false, err
	}
	if !changed {
		return nil, weatherStoriesMeta{}, false, nil
	}

	var meta weatherStoriesMeta
	if err := json.Unmarshal(raw, &meta); err != nil {
		return raw, weatherStoriesMeta{}, true, nil
	}

	for _, story := range meta.Stories {
		if ts := strings.TrimSpace(story.UpdateTime); ts != "" {
			if t, err := nwscommon.ParseTime(ts); err == nil {
				t = t.UTC()
				if meta.ParsedLatestUpdateTime.IsZero() || t.After(meta.ParsedLatestUpdateTime) {
					meta.ParsedLatestUpdateTime = t
				}
			}
		}
		if ts := strings.TrimSpace(story.StartTime); ts != "" {
			if t, err := nwscommon.ParseTime(ts); err == nil {
				t = t.UTC()
				if meta.ParsedLatestStartTime.IsZero() || t.After(meta.ParsedLatestStartTime) {
					meta.ParsedLatestStartTime = t
				}
			}
		}
	}

	return raw, meta, true, nil
}