package db

import (
	"database/sql"
	"fmt"
	"regexp"
	"strconv"

	"github.com/darroyo/nasctl/internal/system"
)

func scanNFSExport(row interface {
	Scan(dest ...any) error
}) (NFSExport, error) {
	var export NFSExport
	var clients, createdAt, updatedAt string
	var readOnly, async_, rootSquash, subtreeCheck, fsid int
	if err := row.Scan(
		&export.ID,
		&export.Path,
		&clients,
		&readOnly,
		&async_,
		&rootSquash,
		&subtreeCheck,
		&fsid,
		&export.Advanced,
		&createdAt,
		&updatedAt,
	); err != nil {
		return NFSExport{}, err
	}
	var err error
	export.Clients, err = decodeJSONStrings(clients)
	if err != nil {
		return NFSExport{}, err
	}
	export.ReadOnly = readOnly != 0
	export.Async = async_ != 0
	export.RootSquash = rootSquash != 0
	export.SubtreeCheck = subtreeCheck != 0
	export.FSID = int64(fsid)
	export.CreatedAt = parseTime(createdAt)
	export.UpdatedAt = parseTime(updatedAt)
	return export, nil
}

func (d *DB) ListNFSExports() ([]NFSExport, error) {
	rows, err := d.conn.Query(`
		SELECT id, path, clients, read_only, async_, root_squash, subtree_check, fsid, advanced, created_at, updated_at
		FROM nfs_exports ORDER BY path ASC`)
	if err != nil {
		return nil, fmt.Errorf("list nfs exports: %w", err)
	}
	defer rows.Close()

	var exports []NFSExport
	for rows.Next() {
		export, err := scanNFSExport(rows)
		if err != nil {
			return nil, fmt.Errorf("scan nfs export: %w", err)
		}
		exports = append(exports, export)
	}
	return exports, rows.Err()
}

func (d *DB) GetNFSExport(id int64) (NFSExport, error) {
	row := d.conn.QueryRow(`
		SELECT id, path, clients, read_only, async_, root_squash, subtree_check, fsid, advanced, created_at, updated_at
		FROM nfs_exports WHERE id = ?`, id)
	export, err := scanNFSExport(row)
	if err == sql.ErrNoRows {
		return NFSExport{}, fmt.Errorf("nfs export not found")
	}
	if err != nil {
		return NFSExport{}, fmt.Errorf("get nfs export: %w", err)
	}
	return export, nil
}

func (d *DB) CreateNFSExport(export NFSExport) (NFSExport, error) {
	clients, err := encodeJSONStrings(export.Clients)
	if err != nil {
		return NFSExport{}, err
	}
	readOnly := 0
	if export.ReadOnly {
		readOnly = 1
	}
	async_ := 0
	if export.Async {
		async_ = 1
	}
	rootSquash := 0
	if export.RootSquash {
		rootSquash = 1
	}
	subtreeCheck := 0
	if export.SubtreeCheck {
		subtreeCheck = 1
	}
	advanced := export.Advanced
	if advanced == "" {
		advanced = "{}"
	}
	result, err := d.conn.Exec(`
		INSERT INTO nfs_exports (path, clients, read_only, async_, root_squash, subtree_check, fsid, advanced)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
		export.Path, clients, readOnly, async_, rootSquash, subtreeCheck, export.FSID, advanced,
	)
	if err != nil {
		return NFSExport{}, fmt.Errorf("create nfs export: %w", err)
	}
	id, err := result.LastInsertId()
	if err != nil {
		return NFSExport{}, fmt.Errorf("last insert id: %w", err)
	}
	return d.GetNFSExport(id)
}

func (d *DB) UpdateNFSExport(id int64, export NFSExport) (NFSExport, error) {
	clients, err := encodeJSONStrings(export.Clients)
	if err != nil {
		return NFSExport{}, err
	}
	readOnly := 0
	if export.ReadOnly {
		readOnly = 1
	}
	async_ := 0
	if export.Async {
		async_ = 1
	}
	rootSquash := 0
	if export.RootSquash {
		rootSquash = 1
	}
	subtreeCheck := 0
	if export.SubtreeCheck {
		subtreeCheck = 1
	}
	advanced := export.Advanced
	if advanced == "" {
		advanced = "{}"
	}
	result, err := d.conn.Exec(`
		UPDATE nfs_exports
		SET path = ?, clients = ?, read_only = ?, async_ = ?, root_squash = ?, subtree_check = ?, fsid = ?, advanced = ?, updated_at = datetime('now')
		WHERE id = ?`,
		export.Path, clients, readOnly, async_, rootSquash, subtreeCheck, export.FSID, advanced, id,
	)
	if err != nil {
		return NFSExport{}, fmt.Errorf("update nfs export: %w", err)
	}
	rows, err := result.RowsAffected()
	if err != nil {
		return NFSExport{}, err
	}
	if rows == 0 {
		return NFSExport{}, fmt.Errorf("nfs export not found")
	}
	return d.GetNFSExport(id)
}

func (d *DB) DeleteNFSExport(id int64) error {
	result, err := d.conn.Exec(`DELETE FROM nfs_exports WHERE id = ?`, id)
	if err != nil {
		return fmt.Errorf("delete nfs export: %w", err)
	}
	rows, err := result.RowsAffected()
	if err != nil {
		return err
	}
	if rows == 0 {
		return fmt.Errorf("nfs export not found")
	}
	return nil
}

func (d *DB) GetAllFSIDs() ([]int64, error) {
	rows, err := d.conn.Query(`SELECT fsid FROM nfs_exports WHERE fsid != 0`)
	if err != nil {
		return nil, fmt.Errorf("get all fsids: %w", err)
	}
	defer rows.Close()
	var fsids []int64
	for rows.Next() {
		var fsid int64
		if err := rows.Scan(&fsid); err != nil {
			return nil, err
		}
		fsids = append(fsids, fsid)
	}
	return fsids, rows.Err()
}

func (d *DB) FSIDExists(fsid int64) (bool, error) {
	var count int
	err := d.conn.QueryRow(`SELECT COUNT(1) FROM nfs_exports WHERE fsid = ?`, fsid).Scan(&count)
	if err != nil {
		return false, err
	}
	return count > 0, nil
}

var fsidLegacyPattern = regexp.MustCompile(`fsid=(\d+)`)

func (d *DB) PopulateLegacyFSIDs() error {
	rows, err := d.conn.Query(`SELECT id, fsid, options FROM nfs_exports WHERE fsid = 0`)
	if err != nil {
		return fmt.Errorf("query legacy fsids: %w", err)
	}
	defer rows.Close()

	type pending struct {
		id   int64
		fsid int64
	}
	var updates []pending

	for rows.Next() {
		var id, fsid int64
		var options string
		if err := rows.Scan(&id, &fsid, &options); err != nil {
			return fmt.Errorf("scan row: %w", err)
		}
		newFSID := int64(0)

		if m := fsidLegacyPattern.FindStringSubmatch(options); m != nil {
			if n, err := strconv.ParseInt(m[1], 10, 64); err == nil && n > 0 {
				newFSID = n
			}
		}

		if newFSID == 0 {
			n, err := system.GenerateRandomFSID()
			if err != nil {
				return fmt.Errorf("generate fsid: %w", err)
			}
			newFSID = int64(n)
		}

		updates = append(updates, pending{id, newFSID})
	}
	if err := rows.Err(); err != nil {
		return fmt.Errorf("rows iteration: %w", err)
	}

	for _, u := range updates {
		if _, err := d.conn.Exec(`UPDATE nfs_exports SET fsid = ? WHERE id = ?`, u.fsid, u.id); err != nil {
			return fmt.Errorf("update fsid for id %d: %w", u.id, err)
		}
	}
	return nil
}