package store

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

	"plumber/internal/store/sqlc"
)

// Vote toggles or sets a user's vote on a question (value must be 1 or -1).
func Vote(ctx context.Context, db *sql.DB, userID, questionID string, value int) error {
	if value != 1 && value != -1 {
		return fmt.Errorf("invalid vote")
	}
	tx, err := db.BeginTx(ctx, nil)
	if err != nil {
		return err
	}
	defer tx.Rollback()

	q := sqlc.New(tx)
	current, err := q.GetVote(ctx, sqlc.GetVoteParams{UserID: userID, QuestionID: questionID})
	if err != nil && err != sql.ErrNoRows {
		return err
	}
	if err == nil && int(current) == value {
		err = q.DeleteVote(ctx, sqlc.DeleteVoteParams{UserID: userID, QuestionID: questionID})
	} else {
		err = q.UpsertVote(ctx, sqlc.UpsertVoteParams{
			UserID:     userID,
			QuestionID: questionID,
			Value:      int32(value),
		})
	}
	if err != nil {
		return err
	}
	return tx.Commit()
}