package dbx

import (
	"fmt"

	"github.com/go-jet/jet/v2/mysql"
)

// CountResult holds the count from a Jet COUNT query. Use with a SELECT that
// aliases the count as `CountResult.Count`, for example:
//
//	SELECT(mysql.COUNT(col).AS("CountResult.Count"))
type CountResult struct {
	Count int
}

// QueryCountFn counts rows matching pre-bound table and condition parameters.
type QueryCountFn func(sqlo Queryable) (int, error)

// QueryCount counts rows in tbl matching conds.
func QueryCount(
	sqlo Queryable,
	col Column,
	tbl ReadableTable,
	conds BoolExpression,
) (int, error) {
	stmt := tbl.SELECT(mysql.COUNT(col).AS("CountResult.Count")).WHERE(conds)
	var res CountResult
	if err := stmt.Query(sqlo, &res); err != nil {
		return 0, fmt.Errorf("query count: %w", err)
	}
	return res.Count, nil
}

// BuildQueryCountFn returns a QueryCountFn with col, tbl, and conds bound.
func BuildQueryCountFn(
	col Column,
	tbl ReadableTable,
	conds BoolExpression,
) QueryCountFn {
	return func(sqlo Queryable) (int, error) {
		return QueryCount(sqlo, col, tbl, conds)
	}
}