package taste

import (
	"context"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"os"
	"path/filepath"
	"sync/atomic"
	"testing"
	"time"

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

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

var seedCounter uint64

func discardLogger() *slog.Logger { return slog.New(slog.NewTextHandler(io.Discard, nil)) }

func newPool(t *testing.T) *pgxpool.Pool {
	t.Helper()
	if testing.Short() {
		t.Skip("skipping integration test in -short mode")
	}
	dsn := os.Getenv("MINSTREL_TEST_DATABASE_URL")
	if dsn == "" {
		t.Skip("MINSTREL_TEST_DATABASE_URL not set")
	}
	if err := db.Migrate(dsn, discardLogger()); err != nil {
		t.Fatalf("migrate: %v", err)
	}
	pool, err := pgxpool.New(context.Background(), dsn)
	if err != nil {
		t.Fatalf("pool: %v", err)
	}
	t.Cleanup(pool.Close)
	dbtest.ResetDB(t, pool)
	return pool
}

func seedUser(t *testing.T, pool *pgxpool.Pool, name string) dbq.User {
	t.Helper()
	u, err := dbq.New(pool).CreateUser(context.Background(), dbq.CreateUserParams{
		Username: dbtest.TestUserPrefix + name, PasswordHash: "x",
		ApiToken: name + "-token", IsAdmin: false,
	})
	if err != nil {
		t.Fatalf("seed user: %v", err)
	}
	return u
}

func seedArtist(t *testing.T, pool *pgxpool.Pool, name string) dbq.Artist {
	t.Helper()
	a, err := dbq.New(pool).UpsertArtist(context.Background(), dbq.UpsertArtistParams{
		Name: name, SortName: name,
	})
	if err != nil {
		t.Fatalf("seed artist: %v", err)
	}
	return a
}

// seedTrack creates an album + track under the given artist with a genre.
func seedTrack(t *testing.T, pool *pgxpool.Pool, artistID pgtype.UUID, genre string) dbq.Track {
	t.Helper()
	q := dbq.New(pool)
	n := atomic.AddUint64(&seedCounter, 1)
	al, err := q.UpsertAlbum(context.Background(), dbq.UpsertAlbumParams{
		Title: fmt.Sprintf("Album %d", n), SortTitle: fmt.Sprintf("Album %d", n), ArtistID: artistID,
	})
	if err != nil {
		t.Fatalf("seed album: %v", err)
	}
	g := genre
	tk, err := q.UpsertTrack(context.Background(), dbq.UpsertTrackParams{
		Title: fmt.Sprintf("Track %d", n), AlbumID: al.ID, ArtistID: artistID,
		DurationMs: 200000, FilePath: filepath.Join(t.TempDir(), fmt.Sprintf("t%d.mp3", n)),
		FileSize: 100, FileFormat: "mp3", Genre: &g,
	})
	if err != nil {
		t.Fatalf("seed track: %v", err)
	}
	return tk
}

// seedPlay inserts a play with an explicit completion_ratio at startedAt.
func seedPlay(t *testing.T, pool *pgxpool.Pool, userID, trackID pgtype.UUID, startedAt time.Time, completion float64) {
	t.Helper()
	_, err := pool.Exec(context.Background(), `
		WITH s AS (
			INSERT INTO play_sessions (user_id, started_at, last_event_at)
			VALUES ($1, $3, $3) RETURNING id
		)
		INSERT INTO play_events (user_id, track_id, session_id, started_at, completion_ratio, was_skipped)
		SELECT $1, $2, s.id, $3, $4, false FROM s
	`, userID, trackID, startedAt, completion)
	if err != nil {
		t.Fatalf("seed play: %v", err)
	}
}

func artistWeight(t *testing.T, pool *pgxpool.Pool, userID, artistID pgtype.UUID) (float64, bool) {
	t.Helper()
	var w float64
	err := pool.QueryRow(context.Background(),
		`SELECT weight FROM taste_profile_artists WHERE user_id = $1 AND artist_id = $2`,
		userID, artistID).Scan(&w)
	if errors.Is(err, pgx.ErrNoRows) {
		return 0, false
	}
	if err != nil {
		t.Fatalf("artist weight: %v", err)
	}
	return w, true
}

func tagWeight(t *testing.T, pool *pgxpool.Pool, userID pgtype.UUID, tag string) (float64, bool) {
	t.Helper()
	var w float64
	err := pool.QueryRow(context.Background(),
		`SELECT weight FROM taste_profile_tags WHERE user_id = $1 AND tag = $2`,
		userID, tag).Scan(&w)
	if errors.Is(err, pgx.ErrNoRows) {
		return 0, false
	}
	if err != nil {
		t.Fatalf("tag weight: %v", err)
	}
	return w, true
}

// TestBuildTasteProfile_PositiveVsNegative: a completed-track artist earns a
// positive weight; an early-skipped artist earns a negative one. Genre tags
// follow the same sign.
func TestBuildTasteProfile_PositiveVsNegative(t *testing.T) {
	pool := newPool(t)
	now := time.Now().UTC()
	u := seedUser(t, pool, "tp1")

	loved := seedArtist(t, pool, "Loved")
	lovedTrack := seedTrack(t, pool, loved.ID, "Rock")
	skipped := seedArtist(t, pool, "Skipped")
	skippedTrack := seedTrack(t, pool, skipped.ID, "Noise")
	for i := 0; i < 3; i++ {
		seedPlay(t, pool, u.ID, lovedTrack.ID, now.Add(-time.Duration(i+1)*time.Hour), 1.0)
		seedPlay(t, pool, u.ID, skippedTrack.ID, now.Add(-time.Duration(i+1)*time.Hour), 0.02)
	}

	if err := BuildTasteProfile(context.Background(), pool, discardLogger(), u.ID, DefaultConfig()); err != nil {
		t.Fatalf("build: %v", err)
	}

	lw, ok := artistWeight(t, pool, u.ID, loved.ID)
	if !ok || lw <= 0 {
		t.Errorf("loved artist weight = %.3f (present=%v), want > 0", lw, ok)
	}
	sw, ok := artistWeight(t, pool, u.ID, skipped.ID)
	if !ok || sw >= 0 {
		t.Errorf("skipped artist weight = %.3f (present=%v), want < 0", sw, ok)
	}
	if rw, ok := tagWeight(t, pool, u.ID, "Rock"); !ok || rw <= 0 {
		t.Errorf("Rock tag weight = %.3f (present=%v), want > 0", rw, ok)
	}
}

// TestBuildTasteProfile_AggregationProtectsArtist: one early-skip among many
// completed plays must NOT make a loved artist net-negative (the user's
// concern that a track-dislike shouldn't tank the artist).
func TestBuildTasteProfile_AggregationProtectsArtist(t *testing.T) {
	pool := newPool(t)
	now := time.Now().UTC()
	u := seedUser(t, pool, "tp2")
	fav := seedArtist(t, pool, "Fav")

	for i := 0; i < 4; i++ {
		tk := seedTrack(t, pool, fav.ID, "Indie")
		seedPlay(t, pool, u.ID, tk.ID, now.Add(-time.Duration(i+1)*time.Hour), 1.0)
		seedPlay(t, pool, u.ID, tk.ID, now.Add(-time.Duration(i+5)*time.Hour), 0.95)
	}
	// One early-skipped track by the same artist.
	skipTrack := seedTrack(t, pool, fav.ID, "Indie")
	seedPlay(t, pool, u.ID, skipTrack.ID, now.Add(-2*time.Hour), 0.02)

	if err := BuildTasteProfile(context.Background(), pool, discardLogger(), u.ID, DefaultConfig()); err != nil {
		t.Fatalf("build: %v", err)
	}
	w, ok := artistWeight(t, pool, u.ID, fav.ID)
	if !ok || w <= 0 {
		t.Errorf("fav artist weight = %.3f (present=%v), want > 0 despite one skip", w, ok)
	}
}

// TestBuildTasteProfile_ArtistLikeBonus: an explicitly-liked artist with no
// plays still earns a positive weight from the like bonus.
func TestBuildTasteProfile_ArtistLikeBonus(t *testing.T) {
	pool := newPool(t)
	u := seedUser(t, pool, "tp3")
	liked := seedArtist(t, pool, "LikedOnly")
	if _, err := pool.Exec(context.Background(),
		`INSERT INTO general_likes_artists (user_id, artist_id) VALUES ($1, $2)`,
		u.ID, liked.ID); err != nil {
		t.Fatalf("seed artist like: %v", err)
	}

	if err := BuildTasteProfile(context.Background(), pool, discardLogger(), u.ID, DefaultConfig()); err != nil {
		t.Fatalf("build: %v", err)
	}
	w, ok := artistWeight(t, pool, u.ID, liked.ID)
	if !ok || w <= 0 {
		t.Errorf("liked-only artist weight = %.3f (present=%v), want > 0 from like bonus", w, ok)
	}
}

// TestBuildTasteProfile_AtomicReplace: a second build replaces, not appends.
func TestBuildTasteProfile_AtomicReplace(t *testing.T) {
	pool := newPool(t)
	ctx := context.Background()
	now := time.Now().UTC()
	u := seedUser(t, pool, "tp4")
	a := seedArtist(t, pool, "A")
	tk := seedTrack(t, pool, a.ID, "Rock")
	seedPlay(t, pool, u.ID, tk.ID, now.Add(-time.Hour), 1.0)

	count := func() int {
		var n int
		if err := pool.QueryRow(ctx,
			`SELECT count(*) FROM taste_profile_artists WHERE user_id = $1`, u.ID).Scan(&n); err != nil {
			t.Fatalf("count: %v", err)
		}
		return n
	}
	for i := 0; i < 2; i++ {
		if err := BuildTasteProfile(ctx, pool, discardLogger(), u.ID, DefaultConfig()); err != nil {
			t.Fatalf("build %d: %v", i, err)
		}
	}
	if got := count(); got != 1 {
		t.Errorf("artist rows after two builds = %d, want 1 (atomic replace)", got)
	}
}