/**
 * Pure utility functions – text processing, date formatting, game detection,
 * priority helpers, template variables.
 */
const crypto = require('crypto');
const { CONFIG, GAME_NAMES, GAME_ALIASES } = require('./config');

/** Constant-time string compare. Returns false for mismatched length or empty/nullish inputs without throwing. */
function safeEqual(a, b) {
  const ab = Buffer.from(String(a || ''), 'utf8');
  const bb = Buffer.from(String(b || ''), 'utf8');
  return ab.length === bb.length && crypto.timingSafeEqual(ab, bb);
}

/** True if the member holds ROLE_ID_TO_PING or any ADDITIONAL_STAFF_ROLES. Safe for null/undefined members. */
function isStaff(member) {
  if (!member?.roles?.cache) return false;
  if (CONFIG.ROLE_ID_TO_PING && member.roles.cache.has(CONFIG.ROLE_ID_TO_PING)) return true;
  const additional = CONFIG.ADDITIONAL_STAFF_ROLES || [];
  return additional.some(roleId => member.roles.cache.has(roleId));
}

// --- TEXT PROCESSING ---

const BLOCK_TAG_REGEX =
  /<\/(p|div|li|h[1-6]|tr|table|section|article|blockquote)>/gi;

function escapeRegex(str) {
  return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}

/** Escape for safe use in HTML body (prevents XSS in outgoing emails). */
function escapeHtml(str) {
  if (str == null) return '';
  return String(str)
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#39;');
}

function decodeHtmlEntities(str) {
  if (!str) return '';
  return str
    .replace(/&amp;/g, '&')
    .replace(/&lt;/g, '<')
    .replace(/&gt;/g, '>')
    .replace(/&quot;/g, '"')
    .replace(/&#39;/g, "'")
    .replace(/&nbsp;/g, ' ');
}

function htmlToTextWithBlocks(html) {
  return decodeHtmlEntities(
    html
      .replace(/\r\n/g, '\n')
      .replace(/<br\s*\/?>/gi, '\n')
      .replace(BLOCK_TAG_REGEX, '\n\n')
      .replace(/<(ul|ol)[^>]*>/gi, '\n')
      .replace(/<[^>]*>?/gm, '')
  );
}

// --- EMAIL BODY EXTRACTION ---

function decodeGmailData(p) {
  if (!p.body?.data) return '';
  let data = Buffer.from(p.body.data, 'base64').toString('utf8');

  const isQuotedPrintable = p.headers?.some(
    h =>
      h.name.toLowerCase() === 'content-transfer-encoding' &&
      h.value.toLowerCase() === 'quoted-printable'
  );
  if (isQuotedPrintable) {
    data = data
      .replace(/=\r?\n/g, '')
      .replace(/=([0-9A-F]{2})/gi, (m, hex) =>
        String.fromCharCode(parseInt(hex, 16))
      );
  }
  return data;
}

function getCleanBody(payload) {
  let body = '';

  const findParts = parts => {
    for (const part of parts) {
      if (part.mimeType === 'text/plain' && part.body?.data && !body) {
        body = decodeGmailData(part);
      }
      if (part.mimeType === 'text/html' && part.body?.data && !body) {
        body = decodeGmailData(part);
      }
      if (part.parts) findParts(part.parts);
    }
  };

  if (payload.parts) {
    findParts(payload.parts);
  } else if (payload.body?.data) {
    body = decodeGmailData(payload);
  }

  return body || payload.snippet || '';
}

// --- QUOTE / FOOTER STRIPPING ---

function stripEmailQuotes(text) {
  let cleaned = text.replace(/\r\n/g, '\n');

  const markers = [
    /\n_{5,}\s*$/m,
    /\nFrom:\s.*<.*@.*>/i,
    /\nSent:\s.*$/i,
    /\nTo:\s.*$/i,
    /\nSubject:\s.*$/i,
    /\nOn .* wrote:/i
  ];

  for (const m of markers) {
    const match = cleaned.match(m);
    if (match) {
      cleaned = cleaned.substring(0, match.index);
      break;
    }
  }

  return cleaned.trim();
}

// Hoisted to module scope: constructed once at load, not per-call.
const MOBILE_FOOTER_REGEXES = [
  /Sent from my iPhone/i,
  /Sent from my iPad/i,
  /Sent from my Apple Watch/i,
  /Sent from my Mac/i,
  /Sent from my mobile device/i,
  /Sent from my phone/i,
  /Sent from my smartphone/i,
  /Sent from my Android(?: phone| device)?/i,
  /Sent from my Samsung Galaxy smartphone/i,
  /Sent from Samsung Mobile/i,
  /Sent from my Galaxy/i,
  /Sent from my BlackBerry/i,
  /Sent from my Windows Phone/i,
  /Sent from Outlook for iOS/i,
  /Sent from Outlook for Android/i,
  /Sent from Yahoo Mail for iPhone(?: \/ Android)?/i,
  /Sent from Yahoo Mail for Android/i,
  /Sent from my Amazon Fire/i,
  /Get\s+Outlook\s+for\s+iOS/i,
  /Get\s+Outlook\s+for\s+Android/i,
  /Sent with Proton Mail secure email\./i
].map(re => new RegExp(`\\n*${re.source}\\s*`, 'i'));

function stripMobileFooter(text) {
  if (!text) return text;
  let result = text;
  for (const rx of MOBILE_FOOTER_REGEXES) {
    result = result.replace(rx, '');
  }
  return result;
}

// --- EMAIL HELPERS ---

function extractRawEmail(headerValue) {
  const match = headerValue.match(/<([^>]+)>/);
  return match ? match[1].trim() : headerValue.trim();
}

// --- DATE ---

const getFormattedDate = () => {
  const now = new Date();
  const datePart = now
    .toLocaleDateString('en-US', {
      month: '2-digit',
      day: '2-digit',
      year: 'numeric'
    })
    .replace(/\//g, '-');
  const timePart = now.toLocaleTimeString('en-US', {
    hour: '2-digit',
    minute: '2-digit',
    second: '2-digit',
    hour12: true
  });
  const tzPart = new Intl.DateTimeFormat('en-US', {
    timeZoneName: 'short'
  })
    .formatToParts(now)
    .find(p => p.type === 'timeZoneName').value;
  return `${datePart} ${timePart} ${tzPart}`;
};

// --- GAME DETECTION ---
// Map<lowercase-alias, { canonical, re }> built once at module load so detectGame
// doesn't allocate a fresh RegExp per game/alias per call.
const GAME_DETECTION = (() => {
  const m = new Map();
  const add = (key, canonical) => {
    const lower = String(key).toLowerCase();
    if (m.has(lower)) return;
    m.set(lower, { canonical, re: new RegExp(`\\b${escapeRegex(lower)}\\b`, 'i') });
  };
  for (const game of GAME_NAMES) add(game, game);
  for (const [alias, fullName] of Object.entries(GAME_ALIASES)) add(alias, fullName);
  return m;
})();

const detectGame = (subject, body) => {
  const txt = `${subject} ${body}`.toLowerCase();
  for (const { re, canonical } of GAME_DETECTION.values()) {
    if (re.test(txt)) return canonical;
  }
  return 'Not Mentioned';
};

// --- PRIORITY ---

function getPriorityEmoji(priority) {
  switch (priority) {
    case 'high': return CONFIG.PRIORITY_HIGH_EMOJI;
    case 'low': return CONFIG.PRIORITY_LOW_EMOJI;
    case 'normal':
    case 'medium':
    default: return CONFIG.PRIORITY_MEDIUM_EMOJI;
  }
}

function getPriorityColor(priority) {
  switch (priority) {
    case 'high': return 0xFF0000;
    case 'low': return 0x00FF00;
    case 'normal':
    case 'medium':
    default: return CONFIG.EMBED_COLOR_INFO;
  }
}

// --- TEMPLATE VARIABLES ---

function replaceVariables(template, context = {}) {
  if (!template) return '';

  let result = template;

  if (context.ticket) {
    result = result.replace(/{ticket\.user}/g, context.ticket.sender_name || 'Unknown');
    result = result.replace(/{ticket\.creator}/g, context.ticket.sender_name || 'Unknown');
    result = result.replace(/{ticket\.email}/g, context.ticket.senderEmail || '');
    result = result.replace(/{ticket\.number}/g, context.ticket.ticketNumber != null ? context.ticket.ticketNumber : 'N/A');
    result = result.replace(/{ticket\.subject}/g, context.ticket.subject || 'No subject');
    result = result.replace(/{ticket\.claimed}/g, context.ticket.claimedBy ? 'Yes' : 'No');
    result = result.replace(/{ticket\.claimedby}/g, context.ticket.claimedBy || 'Unclaimed');
    result = result.replace(/{ticket\.priority}/g, context.ticket.priority || 'normal');
    result = result.replace(/{ticket\.id}/g, context.ticket.gmailThreadId || '');
  }

  if (context.staff) {
    result = result.replace(/{staff\.user}/g, context.staff.username || '');
    result = result.replace(/{staff\.name}/g, context.staff.displayName || context.staff.username || '');
    result = result.replace(/{staff\.mention}/g, context.staff.mention || '');
  }

  if (context.guild) {
    result = result.replace(/{server\.name}/g, context.guild.name || '');
    result = result.replace(/{server\.membercount}/g, context.guild.memberCount?.toString() || '0');
  }

  if (context.hours !== undefined) {
    result = result.replace(/{hours}/g, context.hours.toString());
  }

  const now = new Date();
  result = result.replace(/{date}/g, now.toLocaleDateString());
  result = result.replace(/{time}/g, now.toLocaleTimeString());

  return result;
}

/** Sanitize user input for safe embedding in Discord code blocks. */
function sanitizeEmbedText(str) {
  if (str == null) return '';
  return String(str).replace(/```/g, "'''").trim();
}

// --- EMBED TRUNCATION ---

/** Truncate a string for use as an embed field value (max 1024). */
function truncateEmbedField(str, max = 1024) {
  if (str == null) return '';
  const s = String(str);
  return s.length > max ? s.slice(0, max - 3) + '...' : s;
}

/** Truncate a string for use as an embed description (max 4096). */
function truncateEmbedDescription(str, max = 4096) {
  if (str == null) return '';
  const s = String(str);
  return s.length > max ? s.slice(0, max - 3) + '...' : s;
}

/**
 * Enforce the 6 000 char total embed limit across an array of EmbedBuilder
 * instances.  Mutates in place: trims the largest description first, then
 * largest field values, until the total is under 6 000 chars.
 * Returns the same array for chaining.
 */
function enforceEmbedLimit(embeds) {
  const charCount = (e) => {
    const d = e.data || {};
    let total = 0;
    if (d.title) total += d.title.length;
    if (d.description) total += d.description.length;
    if (d.footer?.text) total += d.footer.text.length;
    if (d.author?.name) total += d.author.name.length;
    if (d.fields) {
      for (const f of d.fields) {
        if (f.name) total += f.name.length;
        if (f.value) total += f.value.length;
      }
    }
    return total;
  };

  const LIMIT = 6000;

  const totalChars = () => embeds.reduce((sum, e) => sum + charCount(e), 0);

  // Trim largest descriptions first
  while (totalChars() > LIMIT) {
    let largestIdx = -1;
    let largestLen = 0;
    for (let i = 0; i < embeds.length; i++) {
      const desc = embeds[i].data?.description;
      if (desc && desc.length > largestLen) {
        largestLen = desc.length;
        largestIdx = i;
      }
    }
    if (largestIdx === -1 || largestLen <= 4) break;
    const excess = totalChars() - LIMIT;
    const newLen = Math.max(1, largestLen - excess - 3);
    embeds[largestIdx].setDescription(
      embeds[largestIdx].data.description.slice(0, newLen) + '...'
    );
    if (totalChars() <= LIMIT) break;
    // If still over, loop will pick next largest
  }

  // Trim largest field values
  while (totalChars() > LIMIT) {
    let targetEmbed = null;
    let targetFieldIdx = -1;
    let targetLen = 0;
    for (const e of embeds) {
      const fields = e.data?.fields || [];
      for (let fi = 0; fi < fields.length; fi++) {
        if (fields[fi].value && fields[fi].value.length > targetLen) {
          targetLen = fields[fi].value.length;
          targetEmbed = e;
          targetFieldIdx = fi;
        }
      }
    }
    if (!targetEmbed || targetLen <= 4) break;
    const excess = totalChars() - LIMIT;
    const newLen = Math.max(1, targetLen - excess - 3);
    targetEmbed.data.fields[targetFieldIdx].value =
      targetEmbed.data.fields[targetFieldIdx].value.slice(0, newLen) + '...';
  }

  return embeds;
}

module.exports = {
  sanitizeEmbedText,
  truncateEmbedField,
  truncateEmbedDescription,
  enforceEmbedLimit,
  BLOCK_TAG_REGEX,
  escapeRegex,
  escapeHtml,
  safeEqual,
  isStaff,
  decodeHtmlEntities,
  htmlToTextWithBlocks,
  decodeGmailData,
  getCleanBody,
  stripEmailQuotes,
  stripMobileFooter,
  extractRawEmail,
  getFormattedDate,
  detectGame,
  getPriorityEmoji,
  getPriorityColor,
  replaceVariables
};