package notify

import (
	"bytes"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"net/smtp"
	"os"
	"strings"
	"time"

	"github.com/jordan-wright/email"
)

// Config holds notification configuration
type Config struct {
	// Feishu webhook
	FeishuWebhookURL string
	// SMTP
	SMTPHost      string
	SMTPPort      string
	SMTPUser      string
	SMTPPassword  string
	SMTPFrom      string
	NotifyTo      string // comma-separated email recipients
}

// LoadNotifyConfig reads notification config from environment
func LoadNotifyConfig() *Config {
	return &Config{
		FeishuWebhookURL: os.Getenv("FEISHU_WEBHOOK_URL"),
		SMTPHost:         os.Getenv("SMTP_HOST"),
		SMTPPort:         os.Getenv("SMTP_PORT"),
		SMTPUser:         os.Getenv("SMTP_USER"),
		SMTPPassword:     os.Getenv("SMTP_PASSWORD"),
		SMTPFrom:         os.Getenv("SMTP_FROM"),
		NotifyTo:         os.Getenv("NOTIFY_TO"),
	}
}

// IsConfigured returns true if at least one notification channel is configured
func (c *Config) IsConfigured() bool {
	return c.FeishuWebhookURL != "" || (c.SMTPHost != "" && c.NotifyTo != "")
}

// CertInfo holds certificate information for notifications
type CertInfo struct {
	Domain    string     `json:"domain"`
	Status    string     `json:"status"`
	ExpiresAt *time.Time `json:"expires_at"`
	DaysLeft  int        `json:"days_left"`
	Error     string     `json:"error,omitempty"`
}

// NotifyCertExpiring sends notifications for expiring certificates
func (c *Config) NotifyCertExpiring(certs []CertInfo) error {
	if len(certs) == 0 {
		return nil
	}
	if !c.IsConfigured() {
		log.Println("Notification not configured, skipping")
		return nil
	}

	var errs []string

	if c.FeishuWebhookURL != "" {
		if err := c.sendFeishu(certs); err != nil {
			errs = append(errs, fmt.Sprintf("feishu: %v", err))
		}
	}

	if c.SMTPHost != "" && c.NotifyTo != "" {
		if err := c.sendEmail(certs); err != nil {
			errs = append(errs, fmt.Sprintf("email: %v", err))
		}
	}

	if len(errs) > 0 {
		return fmt.Errorf("notification errors: %s", strings.Join(errs, "; "))
	}
	return nil
}

// Feishu message format
type feishuCard struct {
	MsgType string       `json:"msg_type"`
	Card    *feishuCardContent `json:"card"`
}

type feishuCardContent struct {
	Header feishuHeader      `json:"header"`
	Elems  []feishuElement   `json:"elements"`
}

type feishuHeader struct {
	Title    feishuText   `json:"title"`
	Template string       `json:"template"`
}

type feishuText struct {
	Tag     string `json:"tag"`
	Content string `json:"content"`
}

type feishuElement struct {
	Tag  string     `json:"tag"`
	Text *feishuText `json:"text,omitempty"`
	Fields *[]feishuField `json:"fields,omitempty"`
}

type feishuField struct {
	IsShort bool       `json:"is_short"`
	Text    feishuText `json:"text"`
}

func (c *Config) sendFeishu(certs []CertInfo) error {
	// Build card content
	elements := []feishuElement{}

	for _, cert := range certs {
		domainText := fmt.Sprintf("**域名：** %s", cert.Domain)
		statusText := fmt.Sprintf("**状态：** %s", certStatusLabel(cert.Status))
		daysText := fmt.Sprintf("**剩余天数：** %d", cert.DaysLeft)
		expiresText := "**过期时间：** "
		if cert.ExpiresAt != nil {
			expiresText += cert.ExpiresAt.Format("2006-01-02 15:04")
		} else {
			expiresText += "未知"
		}

		elements = append(elements,
			feishuElement{
				Tag: "div",
				Fields: &[]feishuField{
					{IsShort: true, Text: feishuText{Tag: "lark_md", Content: domainText}},
					{IsShort: true, Text: feishuText{Tag: "lark_md", Content: statusText}},
				},
			},
			feishuElement{
				Tag: "div",
				Fields: &[]feishuField{
					{IsShort: true, Text: feishuText{Tag: "lark_md", Content: daysText}},
					{IsShort: true, Text: feishuText{Tag: "lark_md", Content: expiresText}},
				},
			},
			feishuElement{Tag: "hr"},
		)
	}

	// Summary
	expiringCount := 0
	for _, cert := range certs {
		if cert.DaysLeft <= 7 {
			expiringCount++
		}
	}

	// Determine template color
	template := "blue"
	if expiringCount > 0 {
		template = "red"
	}

	card := &feishuCardContent{
		Header: feishuHeader{
			Title: feishuText{
				Tag:     "lark_md",
				Content: fmt.Sprintf("🔐 证书到期提醒 (%d 个证书即将到期)", len(certs)),
			},
			Template: template,
		},
		Elems: elements,
	}

	payload := feishuCard{
		MsgType: "interactive",
		Card:    card,
	}

	data, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("marshal feishu message failed: %v", err)
	}

	resp, err := http.Post(c.FeishuWebhookURL, "application/json", bytes.NewReader(data))
	if err != nil {
		return fmt.Errorf("send feishu message failed: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 300 {
		var result map[string]interface{}
		json.NewDecoder(resp.Body).Decode(&result)
		return fmt.Errorf("feishu webhook returned %d: %v", resp.StatusCode, result)
	}

	log.Printf("Feishu notification sent for %d certificates", len(certs))
	return nil
}

func (c *Config) sendEmail(certs []CertInfo) error {
	// Build HTML email
	var sb strings.Builder
	sb.WriteString(`
<html>
<head><meta charset="utf-8"></head>
<body style="font-family: Arial, sans-serif; padding: 20px; background: #f5f5f5;">
<div style="max-width: 600px; margin: 0 auto; background: white; border-radius: 8px; padding: 24px; box-shadow: 0 2px 8px rgba(0,0,0,0.1);">
<h2 style="color: #1a1a2e;">🔐 证书到期提醒</h2>
<p style="color: #666;">以下证书即将到期或已过期，请及时处理：</p>
<table style="width: 100%; border-collapse: collapse; margin-top: 16px;">
<tr style="background: #1890ff; color: white;">
<th style="padding: 10px; text-align: left;">域名</th>
<th style="padding: 10px; text-align: left;">状态</th>
<th style="padding: 10px; text-align: left;">剩余天数</th>
<th style="padding: 10px; text-align: left;">过期时间</th>
</tr>
`)

	for i, cert := range certs {
		bgColor := "#fff"
		if i%2 == 0 {
			bgColor = "#f8f9fa"
		}
		color := "#333"
		if cert.DaysLeft <= 7 {
			color = "#f5222d"
		} else if cert.DaysLeft <= 30 {
			color = "#fa8c16"
		}

		expiresStr := "未知"
		if cert.ExpiresAt != nil {
			expiresStr = cert.ExpiresAt.Format("2006-01-02 15:04")
		}

		statusStr := certStatusLabel(cert.Status)

		sb.WriteString(fmt.Sprintf(`
<tr style="background: %s;">
<td style="padding: 10px; border-bottom: 1px solid #eee; font-weight: 600; color: %s;">%s</td>
<td style="padding: 10px; border-bottom: 1px solid #eee;">%s</td>
<td style="padding: 10px; border-bottom: 1px solid #eee; color: %s; font-weight: 700;">%d 天</td>
<td style="padding: 10px; border-bottom: 1px solid #eee;">%s</td>
</tr>
`, bgColor, color, cert.Domain, statusStr, color, cert.DaysLeft, expiresStr))
	}

	sb.WriteString(`
</table>
<p style="color: #999; font-size: 12px; margin-top: 24px;">
此邮件由 AutoSSL 证书管理系统自动发送，请勿回复。
</p>
</div>
</body>
</html>
`)

	htmlContent := sb.String()

	// Subject
	subject := fmt.Sprintf("🔐 [AutoSSL] %d 个证书即将到期 - 请及时处理", len(certs))

	e := email.NewEmail()
	e.From = c.SMTPFrom
	if e.From == "" {
		e.From = c.SMTPUser
	}
	e.To = strings.Split(c.NotifyTo, ",")
	e.Subject = subject
	e.HTML = []byte(htmlContent)

	addr := fmt.Sprintf("%s:%s", c.SMTPHost, c.SMTPPort)
	var auth smtp.Auth
	if c.SMTPUser != "" && c.SMTPPassword != "" {
		auth = smtp.PlainAuth("", c.SMTPUser, c.SMTPPassword, c.SMTPHost)
	}

	if err := e.Send(addr, auth); err != nil {
		return fmt.Errorf("send email failed: %v", err)
	}

	log.Printf("Email notification sent to %s for %d certificates", c.NotifyTo, len(certs))
	return nil
}

func certStatusLabel(status string) string {
	switch status {
	case "active":
		return "有效"
	case "expired":
		return "已过期"
	case "error":
		return "错误"
	case "renewing":
		return "续期中"
	case "pending":
		return "申请中"
	default:
		return status
	}
}