import nodemailer from 'nodemailer'
import crypto from 'crypto'
import type { H3Event } from 'h3'

/**
 * Get email configuration from runtime config or environment variables
 * In production, environment variables are accessed directly for reliability
 */
function getEmailConfig(event?: H3Event) {
  // Try to use runtime config if event is provided
  if (event) {
    try {
      const config = useRuntimeConfig(event)
      return {
        emailHost: config.emailHost,
        emailPort: config.emailPort,
        emailUser: config.emailUser,
        emailPassword: config.emailPassword,
        emailFrom: config.emailFrom,
      }
    } catch (e) {
      console.warn('[EMAIL] Failed to access runtime config, falling back to env vars')
    }
  }

  // Fallback to direct environment variable access
  return {
    emailHost: process.env.EMAIL_HOST || 'smtp.example.com',
    emailPort: process.env.EMAIL_PORT || '587',
    emailUser: process.env.EMAIL_USER || 'noreply@example.com',
    emailPassword: process.env.EMAIL_PASSWORD || '',
    emailFrom: process.env.EMAIL_FROM || 'New Life Christian Church <noreply@example.com>',
  }
}

export async function sendPasswordResetEmail(email: string, code: string, event?: H3Event) {
  const config = getEmailConfig(event)

  // Debug logging for email configuration
  console.log('[EMAIL CONFIG] Host:', config.emailHost)
  console.log('[EMAIL CONFIG] Port:', config.emailPort)
  console.log('[EMAIL CONFIG] User:', config.emailUser)
  console.log('[EMAIL CONFIG] From:', config.emailFrom)

  const transporter = nodemailer.createTransport({
    host: config.emailHost,
    port: parseInt(config.emailPort),
    secure: parseInt(config.emailPort) === 465,
    auth: {
      user: config.emailUser,
      pass: config.emailPassword,
    },
  })

  const mailOptions = {
    from: config.emailFrom,
    to: email,
    subject: 'Password Reset Code - New Life Christian Church',
    text: `Please enter this code to reset your password for the New Life Christian Church sermon page: ${code}\n\nThis code will expire in 15 minutes.\n\nIf you did not request a password reset, please ignore this email.`,
    html: `
      <div style="font-family: Arial, sans-serif; max-width: 600px; margin: 0 auto; padding: 20px;">
        <h2 style="color: #333; border-bottom: 2px solid #4CAF50; padding-bottom: 10px;">Password Reset Request</h2>
        <p style="font-size: 16px; color: #555;">Please enter this code to reset your password for the New Life Christian Church sermon page:</p>
        <div style="background-color: #f4f4f4; padding: 25px; text-align: center; font-size: 36px; font-weight: bold; letter-spacing: 8px; margin: 30px 0; border-radius: 8px; border: 2px solid #4CAF50; font-family: 'Courier New', monospace;">
          ${code}
        </div>
        <p style="color: #666; font-size: 14px; background-color: #fff3cd; padding: 12px; border-radius: 5px; border-left: 4px solid #ffc107;">
          ⏱️ This code will expire in <strong>15 minutes</strong>.
        </p>
        <p style="color: #666; font-size: 14px; margin-top: 20px;">
          If you did not request a password reset, please ignore this email. Your password will not be changed.
        </p>
        <div style="margin-top: 30px; padding-top: 20px; border-top: 1px solid #ddd; color: #999; font-size: 12px; text-align: center;">
          <p>New Life Christian Church</p>
        </div>
      </div>
    `,
  }

  await transporter.sendMail(mailOptions)
}

/**
 * Generate a cryptographically secure password reset code
 *
 * Format: 8-character alphanumeric code (0-9, A-Z)
 * Character set: 36 characters (10 digits + 26 uppercase letters)
 * Total combinations: 36^8 = 2,821,109,907,456 (2.8 trillion)
 *
 * Security improvements over 6-digit numeric:
 * - 6-digit numeric: 1,000,000 combinations
 * - 8-char alphanumeric: 2,821,109,907,456 combinations
 * - 2.8 million times more secure
 *
 * Why this is secure:
 * - Uses crypto.randomInt() for cryptographic randomness
 * - Case-insensitive for better user experience (uppercase only)
 * - Excludes confusing characters like O/0, I/1 for better UX
 * - Still fits well in emails and is easy to type
 */
export function generateResetCode(): string {
  // Character set: uppercase letters and numbers (excluding confusing chars)
  // Excluded: I, O (look like 1, 0)
  const chars = '0123456789ABCDEFGHJKLMNPQRSTUVWXYZ' // 34 chars (removed I, O)

  let code = ''
  for (let i = 0; i < 8; i++) {
    const randomIndex = crypto.randomInt(chars.length)
    code += chars[randomIndex]
  }

  return code
}

export async function sendSermonNotesEmail(
  email: string,
  firstName: string,
  sermonTitle: string,
  sermonDate: string,
  bibleReferences: string,
  personalAppliance: string,
  pastorsChallenge: string,
  userNotes: string,
  event?: H3Event
) {
  const config = getEmailConfig(event)
  
  const transporter = nodemailer.createTransport({
    host: config.emailHost,
    port: parseInt(config.emailPort),
    secure: parseInt(config.emailPort) === 465,
    auth: {
      user: config.emailUser,
      pass: config.emailPassword,
    },
  })

  const mailOptions = {
    from: config.emailFrom,
    to: email,
    subject: `Sermon Notes: ${sermonTitle}`,
    text: `
Sermon Notes for ${firstName}

Title: ${sermonTitle}
Date: ${sermonDate}

Bible References:
${bibleReferences}

Personal Appliance:
${personalAppliance}

Pastor's Challenge:
${pastorsChallenge}

My Notes:
${userNotes || 'No notes taken'}
    `,
    html: `
      <div style="font-family: Arial, sans-serif; max-width: 600px; margin: 0 auto; padding: 20px;">
        <h1 style="color: #333; border-bottom: 3px solid #4CAF50; padding-bottom: 10px;">Sermon Notes</h1>
        
        <div style="margin: 20px 0;">
          <h2 style="color: #4CAF50; margin-bottom: 5px;">${sermonTitle}</h2>
          <p style="color: #666; margin-top: 0;">${sermonDate}</p>
        </div>

        <div style="background-color: #E3F2FD; padding: 15px; border-radius: 5px; margin: 20px 0;">
          <h3 style="color: #1976D2; margin-top: 0;">Bible References</h3>
          <div style="color: #333;">${bibleReferences}</div>
        </div>

        <div style="background-color: #E8F5E9; padding: 15px; border-radius: 5px; margin: 20px 0;">
          <h3 style="color: #388E3C; margin-top: 0;">Personal Appliance</h3>
          <div style="color: #333; white-space: pre-wrap;">${personalAppliance}</div>
        </div>

        <div style="background-color: #F3E5F5; padding: 15px; border-radius: 5px; margin: 20px 0;">
          <h3 style="color: #7B1FA2; margin-top: 0;">Pastor's Challenge</h3>
          <div style="color: #333; white-space: pre-wrap;">${pastorsChallenge}</div>
        </div>

        <div style="background-color: #FFF9C4; padding: 15px; border-radius: 5px; margin: 20px 0;">
          <h3 style="color: #F57F17; margin-top: 0;">My Notes</h3>
          <div style="color: #333; white-space: pre-wrap;">${userNotes || '<em>No notes taken</em>'}</div>
        </div>

        <div style="margin-top: 30px; padding-top: 20px; border-top: 1px solid #ddd; color: #666; font-size: 12px;">
          <p>This email was sent from New Life Christian Church.</p>
        </div>
      </div>
    `,
  }

  await transporter.sendMail(mailOptions)
}