package builtin

import (
	"context"
	"fmt"
	"sort"

	"gitea.maximumdirect.net/eric/seriatim/internal/config"
	"gitea.maximumdirect.net/eric/seriatim/internal/model"
	"gitea.maximumdirect.net/eric/seriatim/internal/report"
)

type chronologicalMerger struct{}

func (chronologicalMerger) Name() string {
	return "chronological-merge"
}

func (chronologicalMerger) Merge(ctx context.Context, in []model.CanonicalTranscript, cfg config.Config) (model.MergedTranscript, []report.Event, error) {
	if err := ctx.Err(); err != nil {
		return model.MergedTranscript{}, nil, err
	}

	segments := make([]model.Segment, 0)
	for _, transcript := range in {
		segments = append(segments, transcript.Segments...)
	}

	sort.SliceStable(segments, func(i, j int) bool {
		return model.SegmentLess(segments[i], segments[j])
	})

	return model.MergedTranscript{
			Segments:      segments,
			OverlapGroups: nil,
		}, []report.Event{
			report.Info("merge", "chronological-merge", fmt.Sprintf("merged %d canonical transcript(s) into %d segment(s)", len(in), len(segments))),
		}, nil
}