package services

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
	"sync"
	"time"

	sender "github.com/koddr/go-email-sender"
	"github.com/patbritton/sojorn-backend/internal/config"
	"github.com/rs/zerolog/log"
)

type EmailService struct {
	config       *config.Config
	token        string
	tokenExpires time.Time
	mu           sync.Mutex
}

func NewEmailService(cfg *config.Config) *EmailService {
	return &EmailService{config: cfg}
}

// SendPulse API Structs
type sendPulseAuthResponse struct {
	AccessToken string `json:"access_token"`
	TokenType   string `json:"token_type"`
	ExpiresIn   int    `json:"expires_in"`
}

type sendPulseEmailRequest struct {
	Email sendPulseEmailData `json:"email"`
}

type sendPulseEmailData struct {
	HTML    string              `json:"html"`
	Text    string              `json:"text"`
	Subject string              `json:"subject"`
	From    sendPulseIdentity   `json:"from"`
	To      []sendPulseIdentity `json:"to"`
}

type sendPulseIdentity struct {
	Name  string `json:"name"`
	Email string `json:"email"`
}

func (s *EmailService) SendVerificationEmail(toEmail, toName, token string) error {
	subject := "Verify your Sojorn account"
	apiBase := strings.TrimSuffix(s.config.APIBaseURL, "/api/v1")
	verifyURL := fmt.Sprintf("%s/api/v1/auth/verify?token=%s", apiBase, url.QueryEscape(token))

	title := "Email Verification"
	header := fmt.Sprintf("Hey %s!", toName)
	if toName == "" {
		header = "Hey there!"
	}

	content := `
		<p>Welcome to Sojorn &mdash; your vibrant new social space. We're thrilled to have you join our community!</p>
		<p>To get started in the app, please verify your email address by clicking the button below:</p>
	`

	footer := `
		<table role="presentation" width="100%%" cellpadding="0" cellspacing="0" style="margin-top: 24px;">
			<tr><td style="background: #F9FAFB; border-radius: 8px; padding: 16px;">
				<p style="font-size: 13px; color: #9CA3AF; margin: 0 0 8px 0;">If the button above doesn't work, copy and paste this link into your browser:</p>
				<a href="%s" style="color: #4338CA; text-decoration: underline; word-break: break-all; font-size: 13px;">%s</a>
			</td></tr>
		</table>
	`
	footer = fmt.Sprintf(footer, verifyURL, verifyURL)

	htmlBody := s.buildHTMLEmail(title, header, content, verifyURL, "Verify My Email", footer)

	textBody := fmt.Sprintf("Welcome to Sojorn!\n\nPlease verify your email by visiting this link:\n\n%s\n\nIf you did not create an account, you can ignore this email.", verifyURL)

	return s.sendEmail(toEmail, toName, subject, htmlBody, textBody)
}

func (s *EmailService) SendPasswordResetEmail(toEmail, toName, token string) error {
	subject := "Reset your Sojorn password"
	resetURL := fmt.Sprintf("%s/reset-password?token=%s", s.config.AppBaseURL, url.QueryEscape(token))

	title := "Password Reset"
	header := "Reset your password"
	content := fmt.Sprintf(`
		<p>Hey %s,</p>
		<p>You requested a password reset for your Sojorn account. Click the button below to set a new password:</p>
	`, toName)

	footer := `
		<table role="presentation" width="100%%" cellpadding="0" cellspacing="0" style="margin-top: 24px;">
			<tr><td style="background: #F9FAFB; border-radius: 8px; padding: 16px;">
				<p style="font-size: 13px; color: #9CA3AF; margin: 0 0 8px 0;">If the button doesn't work, copy and paste this link:</p>
				<a href="%s" style="color: #4338CA; text-decoration: underline; word-break: break-all; font-size: 13px;">%s</a>
			</td></tr>
		</table>
		<p style="color: #9CA3AF; font-size: 12px; margin-top: 16px;">This link expires in 1 hour. If you did not request this, you can safely ignore this email.</p>
	`
	footer = fmt.Sprintf(footer, resetURL, resetURL)

	htmlBody := s.buildHTMLEmail(title, header, content, resetURL, "Reset Password", footer)
	textBody := fmt.Sprintf("Reset your Sojorn password by visiting this link:\n\n%s\n\nThis link expires in 1 hour.", resetURL)

	return s.sendEmail(toEmail, toName, subject, htmlBody, textBody)
}

func (s *EmailService) sendEmail(toEmail, toName, subject, htmlBody, textBody string) error {
	// Prefer SendPulse API
	if s.config.SendPulseID != "" && s.config.SendPulseSecret != "" {
		return s.sendViaSendPulse(toEmail, toName, subject, htmlBody, textBody)
	}

	// Fallback to Sender.net API (if configured)
	if s.config.SenderAPIToken != "" {
		log.Warn().Msg("Using deprecated Sender.net API token, consider migrating to SendPulse")
		// Implementation omitted/deprecated to simplify
	}

	if s.config.SMTPHost == "" || s.config.SMTPUser == "" {
		log.Warn().Msg("SMTP not configured, skipping email send")
		return nil
	}

	// SMTP Fallback
	emailSender := sender.NewEmailSender(
		s.config.SMTPUser,
		s.config.SMTPPass,
		s.config.SMTPHost,
		s.config.SMTPPort,
	)

	// SMTP Fallback - Send HTML email
	err := emailSender.SendHTMLEmail(
		"Sojorn",          // from name
		[]string{toEmail}, // recipients
		nil,               // cc
		subject,           // subject
		htmlBody,          // html body
		nil,               // attachments
	)
	if err != nil {
		log.Error().Err(err).Msg("Failed to send email via SMTP")
		return err
	}

	log.Info().Msgf("Email sent to %s via SMTP", toEmail)
	return nil
}

func (s *EmailService) getSendPulseToken() (string, error) {
	s.mu.Lock()
	defer s.mu.Unlock()

	if s.token != "" && time.Now().Before(s.tokenExpires) {
		return s.token, nil
	}

	url := "https://api.sendpulse.com/oauth/access_token"
	payload := map[string]string{
		"grant_type":    "client_credentials",
		"client_id":     s.config.SendPulseID,
		"client_secret": s.config.SendPulseSecret,
	}
	jsonData, _ := json.Marshal(payload)

	resp, err := http.Post(url, "application/json", bytes.NewBuffer(jsonData))
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		log.Error().Str("body", string(body)).Int("status", resp.StatusCode).Msg("Failed to get SendPulse Token")
		return "", fmt.Errorf("failed to auth sendpulse: %d", resp.StatusCode)
	}

	var authResp sendPulseAuthResponse
	if err := json.NewDecoder(resp.Body).Decode(&authResp); err != nil {
		return "", err
	}

	s.token = authResp.AccessToken
	s.tokenExpires = time.Now().Add(time.Duration(authResp.ExpiresIn-60) * time.Second) // Buffer 60s
	log.Info().Msg("Authenticated with SendPulse")

	return s.token, nil
}

func (s *EmailService) sendViaSendPulse(toEmail, toName, subject, htmlBody, textBody string) error {
	token, err := s.getSendPulseToken()
	if err != nil {
		return err
	}

	url := "https://api.sendpulse.com/smtp/emails"

	// Determine correct FROM email
	fromEmail := s.config.SMTPFrom
	if fromEmail == "" {
		fromEmail = "no-reply@sojorn.net"
	}

	reqBody := sendPulseEmailRequest{
		Email: sendPulseEmailData{
			HTML:    htmlBody,
			Text:    textBody,
			Subject: subject,
			From: sendPulseIdentity{
				Name:  "Sojorn",
				Email: fromEmail,
			},
			To: []sendPulseIdentity{
				{Name: toName, Email: toEmail},
			},
		},
	}

	jsonData, _ := json.Marshal(reqBody)
	req, err := http.NewRequest("POST", url, bytes.NewBuffer(jsonData))
	if err != nil {
		return err
	}

	req.Header.Set("Authorization", "Bearer "+token)
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{Timeout: 10 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		log.Error().Err(err).Msg("Failed to call SendPulse API")
		return err
	}
	defer resp.Body.Close()

	bodyBytes, _ := io.ReadAll(resp.Body)
	if resp.StatusCode >= 400 {
		log.Error().Int("status", resp.StatusCode).Str("body", string(bodyBytes)).Msg("SendPulse API Error")

		// If 401, maybe token expired? Reset token and retry once?
		if resp.StatusCode == 401 {
			s.mu.Lock()
			s.token = ""
			s.mu.Unlock()
			// Simple retry logic could be added here
		}

		return fmt.Errorf("sendpulse error: %s", string(bodyBytes))
	}

	log.Info().Msgf("Email sent to %s via SendPulse", toEmail)
	return nil
}

func (s *EmailService) SendBanNotificationEmail(toEmail, toName, reason string) error {
	subject := "Your Sojorn account has been suspended"

	title := "Account Suspended"
	header := "Your account has been suspended"
	content := fmt.Sprintf(`
		<p>Hi %s,</p>
		<p>After a review of your recent activity, your Sojorn account has been <strong>permanently suspended</strong> for violating our <a href="https://sojorn.net/terms" style="color: #4338CA;">Community Guidelines</a>.</p>
		<p style="background: #FEF2F2; border-left: 4px solid #EF4444; padding: 12px 16px; border-radius: 4px; margin: 16px 0;">
			<strong>Reason:</strong> %s
		</p>
		<p>What this means:</p>
		<ul style="text-align: left; color: #4B5563;">
			<li>You will no longer be able to log in or post content</li>
			<li>Your profile will not be visible to other users</li>
		</ul>
		<p>If you believe this action was taken in error, you can submit an appeal. Our team will review your case within 5 business days.</p>
	`, toName, reason)

	appealURL := "mailto:appeals@sojorn.net?subject=Account%20Appeal"
	footer := `<p style="color: #9CA3AF; font-size: 12px; margin-top: 16px;">You can also reply directly to this email to submit your appeal.</p>`

	htmlBody := s.buildHTMLEmail(title, header, content, appealURL, "Submit an Appeal", footer)
	textBody := fmt.Sprintf("Hi %s,\n\nYour Sojorn account has been permanently suspended.\n\nReason: %s\n\nIf you believe this was in error, reply to this email or contact appeals@sojorn.net.\n\n— The Sojorn Team", toName, reason)

	return s.sendEmail(toEmail, toName, subject, htmlBody, textBody)
}

func (s *EmailService) SendSuspensionNotificationEmail(toEmail, toName, reason, duration string) error {
	subject := "Your Sojorn account has been temporarily suspended"

	title := "Account Temporarily Suspended"
	header := "Your account has been temporarily suspended"
	content := fmt.Sprintf(`
		<p>Hi %s,</p>
		<p>Your Sojorn account has been <strong>temporarily suspended for %s</strong> due to a violation of our <a href="https://sojorn.net/terms" style="color: #4338CA;">Community Guidelines</a>.</p>
		<p style="background: #FFFBEB; border-left: 4px solid #F59E0B; padding: 12px 16px; border-radius: 4px; margin: 16px 0;">
			<strong>Reason:</strong> %s
		</p>
		<p>Your account will be automatically restored after the suspension period. Further violations may result in a permanent ban.</p>
	`, toName, duration, reason)

	footer := ``
	htmlBody := s.buildHTMLEmail(title, header, content, "https://sojorn.net/terms", "Review Community Guidelines", footer)
	textBody := fmt.Sprintf("Hi %s,\n\nYour Sojorn account has been temporarily suspended for %s.\n\nReason: %s\n\nYour account will be restored after the suspension period.\n\n— The Sojorn Team", toName, duration, reason)

	return s.sendEmail(toEmail, toName, subject, htmlBody, textBody)
}

func (s *EmailService) SendPostRemovalEmail(toEmail, toName, reason string, strikeCount int) error {
	subject := "A post on your Sojorn account was removed"

	title := "Content Removed"
	header := "Your post has been removed"

	strikeWarning := ""
	if strikeCount >= 5 {
		strikeWarning = `<p style="color: #EF4444; font-weight: 600;">Warning: You are close to a permanent suspension. Please review our Community Guidelines carefully.</p>`
	} else if strikeCount >= 3 {
		strikeWarning = `<p style="color: #F59E0B; font-weight: 600;">Continued violations may result in a temporary or permanent suspension of your account.</p>`
	}

	content := fmt.Sprintf(`
		<p>Hi %s,</p>
		<p>One of your posts has been removed by our moderation team for violating our <a href="https://sojorn.net/terms" style="color: #4338CA;">Community Guidelines</a>.</p>
		<p style="background: #FEF2F2; border-left: 4px solid #EF4444; padding: 12px 16px; border-radius: 4px; margin: 16px 0;">
			<strong>Reason:</strong> %s
		</p>
		<p>This is <strong>strike %d</strong> on your account. Strikes are tracked over a 30-day rolling window.</p>
		%s
		<p>If you believe this was in error, you can reply to this email.</p>
	`, toName, reason, strikeCount, strikeWarning)

	footer := ``
	htmlBody := s.buildHTMLEmail(title, header, content, "https://sojorn.net/terms", "Review Community Guidelines", footer)
	textBody := fmt.Sprintf("Hi %s,\n\nOne of your posts has been removed.\n\nReason: %s\nStrike %d on your account.\n\nPlease review our Community Guidelines.\n\n— The Sojorn Team", toName, reason, strikeCount)

	return s.sendEmail(toEmail, toName, subject, htmlBody, textBody)
}

func (s *EmailService) AddSubscriber(email, name string) {
	// SendPulse Addressbook API implementation omitted for brevity, focusing on email first
	// Endpoint: POST /addressbooks/{id}/emails
}

func (s *EmailService) buildHTMLEmail(title, header, content, buttonURL, buttonText, footer string) string {
	return fmt.Sprintf(`<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml" xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="x-apple-disable-message-reformatting">
    <title>%s</title>
    <!--[if mso]>
    <noscript><xml><o:OfficeDocumentSettings><o:PixelsPerInch>96</o:PixelsPerInch></o:OfficeDocumentSettings></xml></noscript>
    <![endif]-->
    <style>
        body, table, td, a { -webkit-text-size-adjust: 100%%; -ms-text-size-adjust: 100%%; }
        table, td { mso-table-lspace: 0pt; mso-table-rspace: 0pt; }
        img { -ms-interpolation-mode: bicubic; border: 0; height: auto; line-height: 100%%; outline: none; text-decoration: none; }
        body { margin: 0; padding: 0; width: 100%% !important; }
        a[x-apple-data-detectors] { color: inherit !important; text-decoration: none !important; font-size: inherit !important; font-family: inherit !important; font-weight: inherit !important; line-height: inherit !important; }
    </style>
</head>
<body style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif; margin: 0; padding: 0; background-color: #F3F4F6; width: 100%%;">
    <table role="presentation" width="100%%" cellpadding="0" cellspacing="0" style="background-color: #F3F4F6;">
        <tr><td style="padding: 40px 20px;">
            <table role="presentation" width="520" cellpadding="0" cellspacing="0" align="center" style="max-width: 520px; margin: 0 auto; background-color: #ffffff; border-radius: 16px; overflow: hidden;">
                <!-- Header -->
                <tr><td style="background-color: #4338CA; padding: 40px; text-align: center;">
                    <img src="https://sojorn.net/web.png" alt="Sojorn" width="80" height="80" style="width: 80px; height: 80px; border-radius: 20px; margin-bottom: 16px; display: block; margin-left: auto; margin-right: auto;">
                    <p style="color: #ffffff; font-size: 12px; font-weight: 600; letter-spacing: 1px; text-transform: uppercase; margin: 0;">%s</p>
                </td></tr>
                
                <!-- Content -->
                <tr><td style="padding: 40px; text-align: center; color: #374151;">
                    <h1 style="color: #1F2937; font-size: 24px; font-weight: 700; margin: 0 0 16px 0;">%s</h1>
                    <div style="font-size: 16px; line-height: 1.6; color: #4B5563; margin-bottom: 32px; text-align: left;">
                        %s
                    </div>
                    
                    <!-- Button (table-based for Outlook) -->
                    <table role="presentation" cellpadding="0" cellspacing="0" align="center" style="margin: 0 auto;">
                        <tr><td style="background-color: #4338CA; border-radius: 12px; text-align: center;">
                            <a href="%s" target="_blank" style="display: block; padding: 16px 40px; color: #ffffff; text-decoration: none; font-weight: 600; font-size: 16px; font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;">%s</a>
                        </td></tr>
                    </table>
                    
                    %s
                </td></tr>
                
                <!-- Footer -->
                <tr><td style="padding: 32px; text-align: center; background-color: #F9FAFB; border-top: 1px solid #E5E7EB;">
                    <p style="font-size: 12px; color: #9CA3AF; margin: 0 0 8px 0;">&copy; 2026 Sojorn by MPLS LLC. All rights reserved.</p>
                    <p style="font-size: 12px; color: #9CA3AF; margin: 0;">
                        <a href="https://sojorn.net" style="color: #9CA3AF; text-decoration: none;">Website</a> &bull; 
                        <a href="https://sojorn.net/privacy" style="color: #9CA3AF; text-decoration: none;">Privacy</a> &bull; 
                        <a href="https://sojorn.net/terms" style="color: #9CA3AF; text-decoration: none;">Terms</a>
                    </p>
                </td></tr>
            </table>
        </td></tr>
    </table>
</body>
</html>`, title, title, header, content, buttonURL, buttonText, footer)
}