/**
 * Shared block scanning utilities — safe for both CLI and browser.
 *
 * Parses fenced code blocks with attributes:
 *   ```lang id=xxx role=xxx as=xxx
 *
 * - `role` dispatches to content scanners (declare, spark-table)
 * - `as` controls rendering (none, codeblock, md-table, md-card, md-dice)
 * - `id` is used for cross-references (file paths)
 */

// ---------------------------------------------------------------------------
// Types
// ---------------------------------------------------------------------------

export interface BlockAttrs {
  lang: string;
  id?: string;
  role?: string;
  as?: string;
  /** Any other attributes not in the standard set */
  extra: Record<string, string>;
}

// ---------------------------------------------------------------------------
// Regex
// ---------------------------------------------------------------------------

/** Matches fenced code blocks with an info string (at least one attr). */
export const FENCED_BLOCK_RE = /^```(\w*)\s+(\S.*?)\s*\n([\s\S]*?)```\s*$/gm;

// ---------------------------------------------------------------------------
// Attribute parsing
// ---------------------------------------------------------------------------

/** Parse key="value" and key=value pairs from an attribute string. */
export function parseBlockAttrs(info: string): BlockAttrs {
  const attrs: Record<string, string> = {};
  const re = /(\w+)\s*=\s*("[^"]*"|\S+)/g;
  let m: RegExpExecArray | null;
  while ((m = re.exec(info)) !== null) {
    attrs[m[1]] = m[2].replace(/^"|"$/g, "");
  }

  const { lang, id, role, as, ...extra } = attrs;
  return { lang: lang || "", id, role, as, extra };
}

// ---------------------------------------------------------------------------
// as resolution
// ---------------------------------------------------------------------------

/**
 * Determine the effective `as` value.
 *
 * Defaults:
 *   - role is set, no explicit as → "none" (strip — it's metadata)
 *   - role=spark-table → "md-table" (render as md-table directive)
 *   - role=tag → "codeblock" (kept for the marked yaml-tag extension)
 *   - no role, no as → "codeblock" (keep as visible code block)
 */
export function resolveBlockAs(role: string | undefined, as: string | undefined): string {
  if (as) return as;
  // spark-table blocks render as md-table by default
  if (role === "spark-table") return "md-table";
  // yaml-defined tag blocks must survive stripping so the
  // code-block-yaml-tag marked extension can render them
  if (role === "tag") return "codeblock";
  if (role) return "none";
  return "codeblock";
}