import { tokenizeInlineLinks } from "./link-tokenizer";

interface InlineContentTextToken {
  kind: "text";
  value: string;
}

interface InlineContentLinkToken {
  kind: "link";
  value: string;
  url: string;
}

interface InlineContentTickerToken {
  kind: "ticker";
  value: string;
  symbol: string;
}

interface InlineContentUsernameToken {
  kind: "username";
  value: string;
  username: string;
}

export type InlineContentToken =
  | InlineContentTextToken
  | InlineContentLinkToken
  | InlineContentTickerToken
  | InlineContentUsernameToken;

const INLINE_SYMBOL_TOKEN_RE = /\$[A-Z][A-Z0-9.-]{0,9}|@[A-Za-z][A-Za-z0-9_]{2,29}/g;
const SYMBOL_CHAR_RE = /[A-Za-z0-9.-]/;
const USERNAME_CHAR_RE = /[A-Za-z0-9_]/;

function trimTrailingTickerPunctuation(value: string): string {
  let trimmed = value;
  while (trimmed.length > 2 && /[.-]$/.test(trimmed)) {
    trimmed = trimmed.slice(0, -1);
  }
  return trimmed;
}

function isValidTickerBoundary(text: string, start: number, end: number): boolean {
  const prev = start > 0 ? text[start - 1] ?? "" : "";
  const next = end < text.length ? text[end] ?? "" : "";
  return !SYMBOL_CHAR_RE.test(prev) && !SYMBOL_CHAR_RE.test(next);
}

function isValidUsernameBoundary(text: string, start: number, end: number): boolean {
  const prev = start > 0 ? text[start - 1] ?? "" : "";
  const next = end < text.length ? text[end] ?? "" : "";
  return !USERNAME_CHAR_RE.test(prev) && !USERNAME_CHAR_RE.test(next);
}

export function tokenizeInlineContent(text: string): InlineContentToken[] {
  const tokens: InlineContentToken[] = [];

  for (const segment of tokenizeInlineLinks(text)) {
    if (segment.kind === "link") {
      tokens.push(segment);
      continue;
    }

    let cursor = 0;
    let match: RegExpExecArray | null;

    INLINE_SYMBOL_TOKEN_RE.lastIndex = 0;
    while ((match = INLINE_SYMBOL_TOKEN_RE.exec(segment.value)) !== null) {
      const rawValue = match[0];
      const start = match.index;
      const rawEnd = start + rawValue.length;
      const isTicker = rawValue.startsWith("$");
      const value = isTicker ? trimTrailingTickerPunctuation(rawValue) : rawValue;
      const end = start + value.length;
      if (
        isTicker
          ? !isValidTickerBoundary(segment.value, start, rawEnd)
          : !isValidUsernameBoundary(segment.value, start, rawEnd)
      ) continue;

      if (start > cursor) {
        tokens.push({ kind: "text", value: segment.value.slice(cursor, start) });
      }
      tokens.push(isTicker
        ? { kind: "ticker", value, symbol: value.slice(1) }
        : { kind: "username", value, username: value.slice(1) });
      cursor = end;
    }

    if (cursor < segment.value.length) {
      tokens.push({ kind: "text", value: segment.value.slice(cursor) });
    }
  }

  return tokens;
}