// Copyright (C) 2024 Mya Pitzeruse
// SPDX-License-Identifier: MIT

package crud

import (
	"context"

	"gorm.io/gorm"
)

// ListFunc defines a function signature used to list data from the underlying gorm database. It ensures that size and
// scoping of queries is taken into consideration.
type ListFunc[T any] func(ctx context.Context, offset, count int, filters ...map[string]interface{}) ([]T, error)

// Lister returns a ListFunc to be used to list data from gorm.
func Lister[T any](db *gorm.DB) ListFunc[T] {
	prototype := new(T)

	return func(ctx context.Context, offset, count int, filters ...map[string]interface{}) ([]T, error) {
		q := Transaction(ctx, db).
			Model(prototype).
			Offset(offset).
			Limit(count)

		for _, filter := range filters {
			q = q.Where(filter)
		}

		result := make([]T, 0, count)

		err := q.Find(&result).Error
		if err != nil {
			return nil, err
		}

		return result, nil
	}
}