export type ChatTextSeg = {
  text: string;
  mention?: boolean;
  hit?: boolean;
  bold?: boolean;
  italic?: boolean;
  link?: string;
  /** deep CRM link */
  crm?: { kind: 'person' | 'deal' | 'ticket'; id: string };
  listItem?: boolean;
};

const URL_RE =
  /https?:\/\/[^\s<>"'`]+|(?:www\.)[^\s<>"'`]+/gi;
const CRM_RE = /mento:\/\/(person|deal|ticket)\/([A-Za-z0-9_-]+)/gi;
const BOLD_RE = /\*([^*\n]+)\*/g;
const ITALIC_RE = /_([^_\n]+)_/g;
const LIST_LINE_RE = /^\s*[-•]\s+/;

function escapeRegExp(s: string) {
  return s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}

function pushPlain(parts: ChatTextSeg[], text: string) {
  if (text) parts.push({ text });
}

/** Parse one inline run (no newlines) into segments. */
function parseInline(
  raw: string,
  mentionNames: string[],
): ChatTextSeg[] {
  if (!raw) return [];

  type Mark = { start: number; end: number; seg: ChatTextSeg };
  const marks: Mark[] = [];

  const mentionRe = mentionNames.length
    ? new RegExp(
        `(@(?:${mentionNames.map(escapeRegExp).join('|')}))`,
        'g',
      )
    : /(@[^\s@]{2,40})/g;

  for (const m of raw.matchAll(mentionRe)) {
    const start = m.index ?? 0;
    marks.push({
      start,
      end: start + m[0].length,
      seg: { text: m[0], mention: true },
    });
  }

  for (const m of raw.matchAll(CRM_RE)) {
    const start = m.index ?? 0;
    const kind = m[1] as 'person' | 'deal' | 'ticket';
    const id = m[2];
    const label =
      kind === 'person' ? 'شخص' : kind === 'deal' ? 'معامله' : 'تیکت';
    marks.push({
      start,
      end: start + m[0].length,
      seg: { text: label, link: m[0], crm: { kind, id } },
    });
  }

  for (const m of raw.matchAll(URL_RE)) {
    const start = m.index ?? 0;
    let url = m[0];
    // trim trailing punctuation common in Persian/English
    url = url.replace(/[)،.,;:!?]+$/g, '');
    const end = start + url.length;
    const href = url.startsWith('http') ? url : `https://${url}`;
    marks.push({
      start,
      end,
      seg: { text: url, link: href },
    });
  }

  for (const m of raw.matchAll(BOLD_RE)) {
    const start = m.index ?? 0;
    marks.push({
      start,
      end: start + m[0].length,
      seg: { text: m[1], bold: true },
    });
  }

  for (const m of raw.matchAll(ITALIC_RE)) {
    const start = m.index ?? 0;
    marks.push({
      start,
      end: start + m[0].length,
      seg: { text: m[1], italic: true },
    });
  }

  marks.sort((a, b) => a.start - b.start || b.end - a.end);
  const chosen: Mark[] = [];
  let cursor = 0;
  for (const mark of marks) {
    if (mark.start < cursor) continue;
    chosen.push(mark);
    cursor = mark.end;
  }

  const out: ChatTextSeg[] = [];
  let last = 0;
  for (const mark of chosen) {
    if (mark.start > last) pushPlain(out, raw.slice(last, mark.start));
    out.push(mark.seg);
    last = mark.end;
  }
  if (last < raw.length) pushPlain(out, raw.slice(last));
  return out.length ? out : [{ text: raw }];
}

function applyHighlight(parts: ChatTextSeg[], q: string): ChatTextSeg[] {
  const qLower = q.trim().toLowerCase();
  if (!qLower) return parts;
  const out: ChatTextSeg[] = [];
  for (const part of parts) {
    if (part.mention || part.link || part.crm || part.bold || part.italic) {
      out.push(part);
      continue;
    }
    const text = part.text;
    const lower = text.toLowerCase();
    let cursor = 0;
    let found = lower.indexOf(qLower, cursor);
    if (found < 0) {
      out.push(part);
      continue;
    }
    while (found >= 0) {
      if (found > cursor) out.push({ text: text.slice(cursor, found) });
      out.push({ text: text.slice(found, found + q.length), hit: true });
      cursor = found + q.length;
      found = lower.indexOf(qLower, cursor);
    }
    if (cursor < text.length) out.push({ text: text.slice(cursor) });
  }
  return out.length ? out : parts;
}

/**
 * فرمت سبک شبیه تلگرام: *پررنگ*، _ایتالیک_، لیست با - ، لینک http، mento://…
 */
export function parseChatMessageText(
  content: string,
  opts?: { mentionNames?: string[]; highlightQuery?: string },
): ChatTextSeg[] {
  const raw = String(content || '');
  if (!raw) return [];
  const names = [...(opts?.mentionNames || [])]
    .map((n) => n.trim())
    .filter(Boolean)
    .sort((a, b) => b.length - a.length);

  const lines = raw.split('\n');
  const parts: ChatTextSeg[] = [];
  lines.forEach((line, i) => {
    if (i > 0) parts.push({ text: '\n' });
    const isList = LIST_LINE_RE.test(line);
    const body = isList ? line.replace(LIST_LINE_RE, '') : line;
    const inline = parseInline(body, names);
    if (isList) {
      if (!inline.length) {
        parts.push({ text: '• ', listItem: true });
      } else {
        parts.push({ text: '• ', listItem: true });
        for (const seg of inline) parts.push({ ...seg, listItem: true });
      }
    } else {
      parts.push(...inline);
    }
  });

  return applyHighlight(parts.length ? parts : [{ text: raw }], opts?.highlightQuery || '');
}

export function crmPathFor(kind: 'person' | 'deal' | 'ticket', id: string): string {
  if (kind === 'person') return `/contacts/people/${id}`;
  if (kind === 'deal') return `/deals/${id}`;
  return `/tickets/${id}`;
}

export function insertCrmLink(
  kind: 'person' | 'deal' | 'ticket',
  id: string,
  title?: string,
): string {
  const link = `mento://${kind}/${id}`;
  return title ? `${title} ${link}` : link;
}