plumber/internal/store/vote.go

package store

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"strings"

	"github.com/jackc/pgx/v5/pgconn"

	"plumber/internal/store/sqlc"
)

// ErrDuplicateUsername is returned when inserting a username that already exists.
var ErrDuplicateUsername = errors.New("username taken")

// ErrDuplicateEmail is returned when inserting/updating an email that already exists.
var ErrDuplicateEmail = errors.New("email taken")

// ErrHiddenOrMissing is returned when voting on a hidden or unknown question.
var ErrHiddenOrMissing = errors.New("question not votable")

// SetVote sets the user's vote to value (1, -1, or 0 to clear) on a visible question.
func SetVote(ctx context.Context, db *sql.DB, userID, questionID string, value int) error {
	if value != 1 && value != -1 && value != 0 {
		return fmt.Errorf("invalid vote")
	}
	q := sqlc.New(db)
	if value == 0 {
		visible, err := q.QuestionIsVisible(ctx, questionID)
		if err != nil {
			return err
		}
		if !visible {
			return ErrHiddenOrMissing
		}
		return q.DeleteVote(ctx, sqlc.DeleteVoteParams{
			UserID:     userID,
			QuestionID: questionID,
		})
	}
	n, err := q.UpsertVoteOnVisible(ctx, sqlc.UpsertVoteOnVisibleParams{
		UserID:     userID,
		QuestionID: questionID,
		Value:      int32(value),
	})
	if err != nil {
		return mapUniqueViolation(err)
	}
	if n == 0 {
		return ErrHiddenOrMissing
	}
	return nil
}

// Vote is kept as an alias for SetVote for callers that still use the old name.
func Vote(ctx context.Context, db *sql.DB, userID, questionID string, value int) error {
	return SetVote(ctx, db, userID, questionID, value)
}

func mapUniqueViolation(err error) error {
	var pgErr *pgconn.PgError
	if errors.As(err, &pgErr) && pgErr.Code == "23505" {
		if strings.Contains(strings.ToLower(pgErr.ConstraintName), "email") {
			return ErrDuplicateEmail
		}
		return ErrDuplicateUsername
	}
	return err
}