package uploads

import (
	"context"
	"errors"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
)

// EnsureReleaseGroups assigns a stable membership once the complete batch has been processed.
// Metadata confirmation cannot accidentally merge two groups or change another group's job.
func (st *Store) EnsureReleaseGroups(ctx context.Context, batch uuid.UUID) error {
	tx, err := st.pool.Begin(ctx)
	if err != nil {
		return err
	}
	defer func() { _ = tx.Rollback(ctx) }()
	var cover *string
	if err = tx.QueryRow(ctx, `SELECT cover_path FROM upload_batches WHERE id=$1 FOR UPDATE`, batch).Scan(&cover); err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return ErrNotFound
		}
		return err
	}
	var pending bool
	if err = tx.QueryRow(ctx, `SELECT EXISTS(SELECT 1 FROM upload_files WHERE batch_id=$1 AND status IN ('uploading','processing'))`, batch).Scan(&pending); err != nil {
		return err
	}
	if pending {
		return tx.Commit(ctx)
	}
	rows, err := tx.Query(ctx, `SELECT `+fileColumns+fileFrom+` WHERE f.batch_id=$1 AND f.release_group_id IS NULL ORDER BY f.id FOR UPDATE OF f`, batch)
	if err != nil {
		return err
	}
	files := []File{}
	for rows.Next() {
		f, e := scanFile(rows)
		if e != nil {
			rows.Close()
			return e
		}
		files = append(files, f)
	}
	err = rows.Err()
	rows.Close()
	if err != nil {
		return err
	}
	drafts := groupReleaseFiles(files)
	var existing int
	if err = tx.QueryRow(ctx, `SELECT count(*) FROM upload_release_groups WHERE batch_id=$1`, batch).Scan(&existing); err != nil {
		return err
	}
	for _, draft := range drafts {
		group := newID()
		var groupCover *string
		if existing == 0 && len(drafts) == 1 {
			groupCover = cover
		}
		err = tx.QueryRow(ctx, `INSERT INTO upload_release_groups(id,batch_id,grouping_key,artist,album,cover_path) VALUES($1,$2,$3,$4,$5,$6)
 ON CONFLICT(batch_id,grouping_key) DO UPDATE SET grouping_key=EXCLUDED.grouping_key RETURNING id`, group, batch, draft.Key, draft.Artist, draft.Album, groupCover).Scan(&group)
		if err != nil {
			return err
		}
		if _, err = tx.Exec(ctx, `UPDATE upload_files SET release_group_id=$2 WHERE batch_id=$1 AND id=ANY($3::uuid[]) AND release_group_id IS NULL`, batch, group, draft.Files); err != nil {
			return err
		}
		if _, err = tx.Exec(ctx, `INSERT INTO upload_release_jobs(batch_id,group_key) VALUES($1,$2) ON CONFLICT DO NOTHING`, batch, group.String()); err != nil {
			return err
		}
	}
	if _, err = tx.Exec(ctx, `DELETE FROM upload_release_jobs WHERE batch_id=$1 AND group_key=''`, batch); err != nil {
		return err
	}
	return tx.Commit(ctx)
}
func (st *Store) ReleaseGroups(ctx context.Context, batch uuid.UUID) ([]ReleaseGroup, error) {
	rows, err := st.pool.Query(ctx, `SELECT g.id::text,g.artist,g.album,g.cover_path IS NOT NULL,coalesce(j.state,'queued'),array_agg(f.id ORDER BY f.id)
 FROM upload_release_groups g JOIN upload_files f ON f.release_group_id=g.id
 LEFT JOIN upload_release_jobs j ON j.batch_id=g.batch_id AND j.group_key=g.id::text
 WHERE g.batch_id=$1 AND f.status NOT IN ('withdrawn','rejected','expired','invalid')
 GROUP BY g.id,j.state ORDER BY min(f.id::text)`, batch)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := []ReleaseGroup{}
	for rows.Next() {
		var g ReleaseGroup
		if err = rows.Scan(&g.ID, &g.Artist, &g.Album, &g.HasCover, &g.State, &g.FileIDs); err != nil {
			return nil, err
		}
		out = append(out, g)
	}
	return out, rows.Err()
}
func (st *Store) resolveGroupKey(ctx context.Context, batch uuid.UUID, key string) (string, error) {
	if key != "" {
		return key, nil
	}
	err := st.pool.QueryRow(ctx, `SELECT CASE WHEN count(*)=1 THEN min(id::text) ELSE '' END FROM upload_release_groups WHERE batch_id=$1`, batch).Scan(&key)
	return key, err
}
func (st *Store) AllInReleaseGroup(ctx context.Context, batch uuid.UUID, group string) ([]File, error) {
	rows, err := st.pool.Query(ctx, `SELECT `+fileColumns+fileFrom+` WHERE f.batch_id=$1 AND f.release_group_id::text=$2 ORDER BY f.id`, batch, group)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := []File{}
	for rows.Next() {
		f, e := scanFile(rows)
		if e != nil {
			return nil, e
		}
		out = append(out, f)
	}
	if err = rows.Err(); err != nil {
		return nil, err
	}
	if len(out) == 0 {
		return nil, ErrNotFound
	}
	return out, nil
}

func (st *Store) UnusedReleaseCovers(ctx context.Context, batch uuid.UUID) ([]string, error) {
	rows, err := st.pool.Query(ctx, `SELECT DISTINCT cover_path FROM upload_release_groups g WHERE g.batch_id=$1 AND g.cover_path IS NOT NULL
 AND NOT EXISTS(SELECT 1 FROM upload_files f WHERE f.release_group_id=g.id AND f.status::text=ANY($2))
 AND NOT EXISTS(SELECT 1 FROM upload_files active LEFT JOIN upload_release_groups ag ON ag.id=active.release_group_id
 JOIN upload_batches ab ON ab.id=active.batch_id WHERE active.status::text=ANY($2)
 AND (CASE WHEN active.release_group_id IS NULL THEN ab.cover_path ELSE ag.cover_path END)=g.cover_path)`, batch, occupyingStatuses)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	return pgx.CollectRows(rows, pgx.RowTo[string])
}