Backend/src/main/java/cc/fascinated/backend/service/PasteService.java

package cc.fascinated.backend.service;

import cc.fascinated.backend.exception.impl.BadRequestException;
import cc.fascinated.backend.model.Paste;
import cc.fascinated.backend.exception.impl.ResourceNotFoundException;
import cc.fascinated.backend.repository.PasteRepository;
import org.apache.commons.lang3.RandomStringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

import java.util.Optional;

@Service
public class PasteService {

    /**
     * The {@link PasteRepository} instance.
     */
    private final PasteRepository pasteRepository;

    /**
     * The length of the paste id.
     */
    @Value("${paste.id-length}")
    private int idLength;

    /**
     * The maximum size of the paste content.
     */
    @Value("${paste.upload-size-limit}")
    private int uploadSizeLimit;

    @Autowired
    public PasteService(PasteRepository pasteRepository) {
        this.pasteRepository = pasteRepository;
    }

    /**
     * Creates a new paste with the specified content.
     *
     * @param content The content of the paste.
     * @return The id of the paste.
     */
    public String createPaste(String content) {
        int length = content.length();
        if (length > uploadSizeLimit) {
            throw new BadRequestException("The paste content is too large, the limit is " + uploadSizeLimit + " characters");
        }

        return pasteRepository.save(new Paste(
                RandomStringUtils.randomAlphabetic(idLength),
                System.currentTimeMillis(),
                content
        )).getId();
    }

    /**
     * Gets the content of the paste with the specified id.
     *
     * @param id The id of the paste.
     * @return The content of the paste.
     */
    public Paste getPaste(String id) {
        Optional<Paste> paste = pasteRepository.findById(id);

        // The paste does not exist.
        if (paste.isEmpty()) {
            throw new ResourceNotFoundException("Paste with id '%s' not found".formatted(id));
        }
        return paste.get();
    }
}