package api

import (
	"testing"
	"time"

	"github.com/jackc/pgx/v5/pgtype"

	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
)

func dupUUID(b byte) pgtype.UUID {
	var u pgtype.UUID
	u.Bytes[15] = b
	u.Valid = true
	return u
}

func dupTS(t time.Time) pgtype.Timestamptz { return pgtype.Timestamptz{Time: t, Valid: true} }

// Rows arrive one per member, members of a group together. The fold must keep
// groups apart, keep the query's order, and propose each group's survivor from
// its own members only.
func TestFoldDuplicateGroups(t *testing.T) {
	older := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
	newer := older.Add(48 * time.Hour)
	ber := float32(0.04)
	rows := []dbq.ListPendingDuplicateGroupMembersRow{
		// Group 1: identical audio, sizes tie, the older copy should be kept.
		{GroupID: dupUUID(1), Tier: "exact", DetectedAt: dupTS(newer), TrackID: dupUUID(10),
			Title: "WWW", FileFormat: "mp3", FileSize: 6_900_000, DurationMs: 215_400, AddedAt: dupTS(newer), PlayCount: 3},
		{GroupID: dupUUID(1), Tier: "exact", DetectedAt: dupTS(newer), TrackID: dupUUID(11),
			Title: "WWW", FileFormat: "mp3", FileSize: 6_900_000, DurationMs: 215_400, AddedAt: dupTS(older), LikeCount: 1},
		// Group 2: the same recording, FLAC against MP3.
		{GroupID: dupUUID(2), Tier: "acoustic", WorstBitErrorRate: &ber, DetectedAt: dupTS(older), TrackID: dupUUID(20),
			Title: "Lovesick", FileFormat: "mp3", FileSize: 9_000_000, DurationMs: 198_000, AddedAt: dupTS(older)},
		{GroupID: dupUUID(2), Tier: "acoustic", WorstBitErrorRate: &ber, DetectedAt: dupTS(older), TrackID: dupUUID(21),
			Title: "Lovesick", FileFormat: "flac", FileSize: 30_000_000, DurationMs: 198_000, AddedAt: dupTS(newer)},
	}

	got := foldDuplicateGroups(rows)
	if len(got) != 2 {
		t.Fatalf("folded %d groups, want 2", len(got))
	}

	g1, g2 := got[0], got[1]
	if g1.ID != uuidToString(dupUUID(1)) || len(g1.Members) != 2 || g1.WorstBitErrorRate != nil {
		t.Fatalf("group 1 = %+v, want the exact pair with no score", g1)
	}
	if g1.SurvivorTrackID != uuidToString(dupUUID(11)) || g1.SurvivorReason != "in the library longest" {
		t.Errorf("group 1 survivor = (%s, %q), want the older copy", g1.SurvivorTrackID, g1.SurvivorReason)
	}
	if g1.Members[0].DurationSec != 215 || g1.Members[0].PlayCount != 3 || g1.Members[1].LikeCount != 1 {
		t.Errorf("group 1 members lost their facts: %+v", g1.Members)
	}

	if g2.Tier != "acoustic" || g2.WorstBitErrorRate == nil || *g2.WorstBitErrorRate != ber {
		t.Fatalf("group 2 = %+v, want the acoustic pair with its score", g2)
	}
	// Chosen from group 2's own members: a survivor leaking across groups is
	// exactly what a wrong fold boundary would produce.
	if g2.SurvivorTrackID != uuidToString(dupUUID(21)) || g2.SurvivorReason != "lossless (flac)" {
		t.Errorf("group 2 survivor = (%s, %q), want the FLAC copy", g2.SurvivorTrackID, g2.SurvivorReason)
	}
}