// Copyright 2022 E99p1ant. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package mail

import (
	"bytes"
	"crypto/tls"
	"embed"
	"fmt"
	"html/template"
	"strings"
	"time"

	"github.com/pkg/errors"
	"gopkg.in/gomail.v2"

	"github.com/tamakyi/TamaBox/internal/conf"
	"github.com/tamakyi/TamaBox/templates"
)

func SendNewQuestionMail(email, domain string, questionID uint, questionContent string, token string) error {
	params := map[string]string{
		"link":     fmt.Sprintf("%s/_/%s/%d?t=%s", conf.App.ExternalURL, domain, questionID, token),
		"question": questionContent,
	}
	return sendTemplateMail(email, "【狼的提问箱】您有一个新的提问", templates.FS, "mail/new-question.html", params)
}

func SendNewQuestionMailToUser(email, domain string, questionID uint, questionContent string, token string) error {
	params := map[string]string{
		"link":     fmt.Sprintf("%s/_/%s/%d?t=%s", conf.App.ExternalURL, domain, questionID, token),
		"question": questionContent,
	}
	return sendTemplateMail(email, "【狼的提问箱】您发送了一个新的提问", templates.FS, "mail/new-question-to-user.html", params)
}

func SendNewAnswerMail(email, domain string, questionID uint, question, answer string, token string) error {
	params := map[string]string{
		"link":     fmt.Sprintf("%s/_/%s/%d?t=%s", conf.App.ExternalURL, domain, questionID, token),
		"question": question,
		"answer":   answer,
	}
	return sendTemplateMail(email, "【狼的提问箱】您的提问有了回复", templates.FS, "mail/new-answer.html", params)
}

func SendPasswordRecoveryMail(email, code string) error {
	params := map[string]string{
		"link":  fmt.Sprintf("%s/recover-password?code=%s", conf.App.ExternalURL, code),
		"email": email,
	}
	return sendTemplateMail(email, "【狼的提问箱】账号密码找回", templates.FS, "mail/password-recovery.html", params)
}

// SendNewFollowUpMail 通知提问箱主人：有人对某条已回答的提问进行了追问。
// 链接无需 token，主人登录后即可查看。
func SendNewFollowUpMail(email, domain string, questionID uint, questionContent string, followUpContent string) error {
	params := map[string]string{
		"link":     fmt.Sprintf("%s/_/%s/%d", conf.App.ExternalURL, domain, questionID),
		"question": questionContent,
		"followup": followUpContent,
	}
	return sendTemplateMail(email, "【狼的提问箱】您的提问有了追问", templates.FS, "mail/new-follow-up.html", params)
}

// SendNewConversationMail 通知有新私聊发起（使用 token 而非 conversationID）
func SendNewConversationMail(email, askerName, domain string, token string, firstMessage string) error {
	params := map[string]string{
		"link":    fmt.Sprintf("%s/_/%s/chat/%s", conf.App.ExternalURL, domain, token),
		"asker":   askerName,
		"content": firstMessage,
	}
	return sendTemplateMail(email, "【狼的提问箱】有人发起了私聊", templates.FS, "mail/new-conversation.html", params)
}

// SendNewMessageMail 通知私聊中有新消息（使用 token 而非 conversationID）
func SendNewMessageMail(email, senderName, domain string, token string, content string) error {
	params := map[string]string{
		"link":    fmt.Sprintf("%s/_/%s/chat/%s", conf.App.ExternalURL, domain, token),
		"sender":  senderName,
		"content": content,
	}
	return sendTemplateMail(email, "【狼的提问箱】私聊新消息", templates.FS, "mail/new-message.html", params)
}

// SendNewVoteSubmissionMail 通知箱主：表单投票收到新回复（链接指向管理后台结果页）。
func SendNewVoteSubmissionMail(email, voteTitle string, voteID uint) error {
	params := map[string]string{
		"link":  fmt.Sprintf("%s/user/votes/%d/results", conf.App.ExternalURL, voteID),
		"title": voteTitle,
	}
	return sendTemplateMail(email, "【狼的提问箱】您的投票收到了新回复", templates.FS, "mail/new-vote.html", params)
}

// SendSecurityAlertMail 发送安全告警：检测到疑似批量扫描/探测并触发自动封禁时通知管理员。
// provider 为来源 IP 的网络归属标签（见 internal/security/ipinfo），proxied 表示
// IP 属于 CDN/WAF/代理网络（此时封禁出口 IP 可能无法拦截真实攻击者，邮件中额外提示）。
func SendSecurityAlertMail(ip, provider string, proxied bool, samplePaths []string, durationMinutes int) error {
	proxyHint := ""
	if proxied {
		proxyHint = "1"
	}
	params := map[string]string{
		"ip":         ip,
		"provider":   provider,
		"proxy_hint": proxyHint,
		"paths":      strings.Join(samplePaths, "、"),
		"duration":   fmt.Sprintf("%d", durationMinutes),
		"time":       time.Now().Format("2006-01-02 15:04:05"),
	}
	return sendTemplateMail(conf.Security.SecurityAlertEmail, "【狼的提问箱】检测到疑似批量扫描，已自动封禁 IP", templates.FS, "mail/security-alert.html", params)
}

func sendTemplateMail(email, title string, templateFS embed.FS, templatePath string, params map[string]string) error {
	var content bytes.Buffer
	t, err := template.ParseFS(templateFS, templatePath)
	if err != nil {
		return errors.Wrap(err, "parse template file")
	}
	params["year"] = time.Now().Format("2006")
	if err := t.Execute(&content, params); err != nil {
		return errors.Wrap(err, "execute template")
	}
	return sendMail(email, title, content.String())
}

func sendMail(to, title, content string) error {
	m := gomail.NewMessage()
	m.SetHeader("From", fmt.Sprintf("TamaBox <%s>", conf.Mail.Account))
	m.SetHeader("To", to)
	m.SetHeader("Subject", title)
	m.SetBody("text/html", content)

	d := gomail.NewDialer(
		conf.Mail.SMTP,
		conf.Mail.Port,
		conf.Mail.Account,
		conf.Mail.Password,
	)
	// 默认校验证书；仅当配置了 skip_tls_verify=true（自签名/内网 SMTP）时跳过。
	if conf.Mail.SkipTLSVerify {
		d.TLSConfig = &tls.Config{InsecureSkipVerify: true}
	}
	return d.DialAndSend(m)
}