package db

import (
	"context"
	"database/sql"

	"github.com/pkg/errors"
	"github.com/uptrace/bun"
)

type fieldgetter[T any] struct {
	q     *bun.SelectQuery
	field string
	value any
	model *T
}

func (g *fieldgetter[T]) get(ctx context.Context) (*T, error) {
	if g.field == "id" && (g.value).(int) < 1 {
		return nil, errors.New("invalid id")
	}
	err := g.q.
		Where("? = ?", bun.Ident(g.field), g.value).
		Scan(ctx)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, nil
		}
		return nil, errors.Wrap(err, "bun.SelectQuery.Scan")
	}
	return g.model, nil
}

func (g *fieldgetter[T]) Get(ctx context.Context) (*T, error) {
	g.q = g.q.Limit(1)
	return g.get(ctx)
}

func (g *fieldgetter[T]) Relation(name string, apply ...func(*bun.SelectQuery) *bun.SelectQuery) *fieldgetter[T] {
	g.q = g.q.Relation(name, apply...)
	return g
}

func (g *fieldgetter[T]) Join(join string, args ...any) *fieldgetter[T] {
	g.q = g.q.Join(join, args...)
	return g
}

// GetByField retrieves a single record by field name
func GetByField[T any](
	tx bun.Tx,
	field string,
	value any,
) *fieldgetter[T] {
	model := new(T)
	return &fieldgetter[T]{
		tx.NewSelect().Model(model),
		field,
		value,
		model,
	}
}

func GetByID[T any](
	tx bun.Tx,
	id int,
) *fieldgetter[T] {
	return GetByField[T](tx, "id", id)
}