package com.example.demo.common;

import jakarta.mail.internet.MimeMessage;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.stereotype.Service;

@Service
public class EmailSenderService {
    private final JavaMailSender mailSender;
    private final EmailProperties props;

    @Value("${spring.mail.username:}")
    private String mailUsername;

    public EmailSenderService(JavaMailSender mailSender, EmailProperties props) {
        this.mailSender = mailSender;
        this.props = props;
    }

    public void sendPlainText(String to, String subject, String content) {
        if (to == null || to.isBlank()) throw new IllegalArgumentException("收件人邮箱不能为空");
        if (subject == null) subject = "";
        if (content == null) content = "";
        try {
            MimeMessage message = mailSender.createMimeMessage();
            MimeMessageHelper helper = new MimeMessageHelper(message, false, "UTF-8");
            helper.setFrom(resolveFromAddress());
            helper.setTo(to.trim());
            helper.setSubject(composeSubject(subject));
            helper.setText(content, false);
            mailSender.send(message);
        } catch (IllegalStateException | IllegalArgumentException e) {
            throw e;
        } catch (Exception e) {
            throw new RuntimeException("发送邮件失败: " + e.getMessage(), e);
        }
    }

    private String composeSubject(String subject) {
        String prefix = props.getSubjectPrefix();
        if (prefix == null || prefix.isBlank()) return subject;
        return prefix + " " + subject;
    }

    private String resolveFromAddress() {
        String from = props.getFrom();
        if (from == null || from.isBlank()) from = mailUsername;
        if (from == null || from.isBlank()) {
            throw new IllegalStateException("邮件服务未配置，请设置 MAIL_USERNAME/MAIL_PASSWORD 以及 MAIL_FROM 或 spring.mail.username");
        }
        return from.trim();
    }
}