package files

import (
	"context"
	"errors"
	"fmt"

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

// Auflösung von Pfaden zu Ordnern – gebraucht von WebDAV, das über Pfade
// adressiert statt über IDs.

// ── WebDAV helpers ────────────────────────────────────────────────────────────

// FolderByPath resolves a path like ["photos", "2024"] to a Folder.
// Returns a zero-ID folder for an empty parts slice (root).
func (s *Store) FolderByPath(ctx context.Context, principalID uuid.UUID, parts []string) (*Folder, error) {
	return s.FolderByPathFrom(ctx, principalID, nil, parts)
}

// FolderByPathFrom löst Pfadteile ab einem bestimmten Ordner auf. base == nil
// heißt: ab der Wurzel des Prinzipals.
//
// Der Einstiegspunkt ist nötig, weil WebDAV geteilte Ordner unter einem
// virtuellen Pfad einhängt: Dort beginnt der Weg nicht bei der Wurzel des
// Eigentümers, sondern genau bei dem Ordner, der freigegeben wurde – alles
// darüber geht den Empfänger nichts an.
func (s *Store) FolderByPathFrom(ctx context.Context, principalID uuid.UUID, base *uuid.UUID, parts []string) (*Folder, error) {
	if len(parts) == 0 {
		if base == nil {
			return &Folder{OwnerID: &principalID, Name: "/"}, nil
		}
		return s.folderByID(ctx, *base)
	}
	parentID := base
	var current *Folder
	for _, part := range parts {
		var f Folder
		var err error
		if parentID == nil {
			err = s.db.QueryRow(ctx,
				`SELECT id, owner_id, group_id, parent_id, name, created_at FROM folders
				 WHERE (owner_id = $1 OR group_id = $1) AND parent_id IS NULL AND name=$2`,
				principalID, part,
			).Scan(&f.ID, &f.OwnerID, &f.GroupID, &f.ParentID, &f.Name, &f.CreatedAt)
		} else {
			err = s.db.QueryRow(ctx,
				`SELECT id, owner_id, group_id, parent_id, name, created_at FROM folders
				 WHERE (owner_id = $1 OR group_id = $1) AND parent_id=$2 AND name=$3`,
				principalID, parentID, part,
			).Scan(&f.ID, &f.OwnerID, &f.GroupID, &f.ParentID, &f.Name, &f.CreatedAt)
		}
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, ErrNotFound
		}
		if err != nil {
			return nil, fmt.Errorf("folder by path: %w", err)
		}
		parentID = &f.ID
		current = &f
	}
	return current, nil
}

func (s *Store) folderByID(ctx context.Context, id uuid.UUID) (*Folder, error) {
	var f Folder
	err := s.db.QueryRow(ctx,
		`SELECT id, owner_id, group_id, parent_id, name, created_at FROM folders WHERE id = $1`, id,
	).Scan(&f.ID, &f.OwnerID, &f.GroupID, &f.ParentID, &f.Name, &f.CreatedAt)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, ErrNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("folder by id: %w", err)
	}
	return &f, nil
}

// FileInFolder finds a non-deleted file by name within a folder (nil = root).
func (s *Store) FileInFolder(ctx context.Context, ownerID uuid.UUID, folderID *uuid.UUID, name string) (*File, error) {
	var f File
	var err error
	if folderID == nil {
		err = scanFile(s.db.QueryRow(ctx,
			`SELECT `+fileCols+` FROM files
			 WHERE (owner_id = $1 OR group_id = $1) AND folder_id IS NULL AND name=$2 AND is_deleted=false`,
			ownerID, name,
		), &f)
	} else {
		err = scanFile(s.db.QueryRow(ctx,
			`SELECT `+fileCols+` FROM files
			 WHERE (owner_id = $1 OR group_id = $1) AND folder_id=$2 AND name=$3 AND is_deleted=false`,
			ownerID, folderID, name,
		), &f)
	}
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, ErrNotFound
	}
	return &f, err
}