package musicrepo

import (
	"context"
	"database/sql"
	"time"
)

type QueueEntry struct {
	Title       string
	URL         string
	RequestedBy int64

	// ClientID is the track's stable identity (set once by the manager
	// when a track is first queued), used to upsert this row across
	// syncs instead of assigning it a fresh DB id every single time.
	ClientID string
}

type Repo struct {
	db *sql.DB
}

func NewRepo(db *sql.DB) *Repo {
	return &Repo{db: db}
}

func (r *Repo) SetNowPlaying(ctx context.Context, guildID int64, title, url string, durationSeconds int, startedAt time.Time, paused bool, volume int, repeatSong, repeatQueue bool) error {
	const q = `
		INSERT INTO music_now_playing (guild_id, track_title, track_url, duration_seconds, started_at, paused, volume, repeat_song, repeat_queue)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
		ON CONFLICT (guild_id) DO UPDATE SET
			track_title = $2, track_url = $3, duration_seconds = $4, started_at = $5,
			paused = $6, volume = $7, repeat_song = $8, repeat_queue = $9
	`
	_, err := r.db.ExecContext(ctx, q, guildID, title, url, durationSeconds, startedAt, paused, volume, repeatSong, repeatQueue)
	return err
}

func (r *Repo) ClearNowPlaying(ctx context.Context, guildID int64) error {
	const q = `DELETE FROM music_now_playing WHERE guild_id = $1`
	_, err := r.db.ExecContext(ctx, q, guildID)
	return err
}

// ReplaceQueue syncs music_queue with the current in-memory queue by
// upserting each entry on its stable ClientID, rather than deleting and
// recreating every row on every call. That matters because music_queue.id
// is only an internal DB identity, remove/reorder commands target a
// track by ClientID, and that has to survive a track just sitting in the
// queue unchanged across syncs.
func (r *Repo) ReplaceQueue(ctx context.Context, guildID int64, entries []QueueEntry) error {
	tx, err := r.db.BeginTx(ctx, nil)
	if err != nil {
		return err
	}
	defer tx.Rollback()

	existing := make(map[string]bool)
	rows, err := tx.QueryContext(ctx, `SELECT client_id FROM music_queue WHERE guild_id = $1`, guildID)
	if err != nil {
		return err
	}
	for rows.Next() {
		var clientID string
		if err := rows.Scan(&clientID); err != nil {
			rows.Close()
			return err
		}
		existing[clientID] = true
	}
	if err := rows.Err(); err != nil {
		rows.Close()
		return err
	}
	rows.Close()

	keep := make(map[string]bool, len(entries))
	for i, entry := range entries {
		keep[entry.ClientID] = true
		const q = `
			INSERT INTO music_queue (guild_id, position, track_title, track_url, requested_by, client_id)
			VALUES ($1, $2, $3, $4, $5, $6)
			ON CONFLICT (guild_id, client_id) DO UPDATE SET
				position = EXCLUDED.position,
				track_title = EXCLUDED.track_title,
				track_url = EXCLUDED.track_url,
				requested_by = EXCLUDED.requested_by
		`
		if _, err := tx.ExecContext(ctx, q, guildID, i, entry.Title, entry.URL, entry.RequestedBy, entry.ClientID); err != nil {
			return err
		}
	}

	for clientID := range existing {
		if keep[clientID] {
			continue
		}
		const q = `DELETE FROM music_queue WHERE guild_id = $1 AND client_id = $2`
		if _, err := tx.ExecContext(ctx, q, guildID, clientID); err != nil {
			return err
		}
	}

	return tx.Commit()
}

type MusicCommand struct {
	ID          int64
	GuildID     int64
	CommandType string
	Payload     []byte
	RequestedBy int64
}

func (r *Repo) ListUnprocessedCommands(ctx context.Context) ([]MusicCommand, error) {
	const q = `SELECT id, guild_id, command_type, payload, requested_by FROM music_commands WHERE processed_at IS NULL ORDER BY id ASC`

	rows, err := r.db.QueryContext(ctx, q)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var commands []MusicCommand
	for rows.Next() {
		var cmd MusicCommand
		if err := rows.Scan(&cmd.ID, &cmd.GuildID, &cmd.CommandType, &cmd.Payload, &cmd.RequestedBy); err != nil {
			return nil, err
		}
		commands = append(commands, cmd)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}

	return commands, nil
}

func (r *Repo) MarkCommandProcessed(ctx context.Context, id int64) error {
	const q = `UPDATE music_commands SET processed_at = NOW() WHERE id = $1`
	_, err := r.db.ExecContext(ctx, q, id)
	return err
}