import type { ParsedEdge } from "./types";

const EDGE_HEADER_RE = /^\s*(>+)\s*\[!edge\]\s*(.+?)\s*$/i;
const TARGET_LINK_RE = /\[\[([^\]]+?)\]\]/g;

/**
 * Extract edges from any callout nesting:
 * - Edge starts with: > [!edge] <type> (any number of '>' allowed)
 * - Collect targets from subsequent lines while quoteLevel >= edgeLevel
 * - Stop when:
 *   a) next [!edge] header appears, OR
 *   b) quoteLevel drops below edgeLevel (block ends), ignoring blank lines
 */
export function parseEdgesFromCallouts(markdown: string): ParsedEdge[] {
  const lines = markdown.split(/\r?\n/);
  const edges: ParsedEdge[] = [];

  let current: ParsedEdge | null = null;
  let currentEdgeLevel = 0;

  const getQuoteLevel = (line: string): number => {
    const m = line.match(/^\s*(>+)/);
    return m && m[1] ? m[1].length : 0;
  };

  const flush = (endLine: number) => {
    if (!current) return;
    current.lineEnd = endLine;
    if (current.targets.length > 0) edges.push(current);
    current = null;
    currentEdgeLevel = 0;
  };

  for (let i = 0; i < lines.length; i++) {
    const line = lines[i];
    if (line === undefined) continue;

    // Start of a new edge block
    const edgeMatch = line.match(EDGE_HEADER_RE);
    if (edgeMatch && edgeMatch[1] && edgeMatch[2]) {
      flush(i - 1);

      currentEdgeLevel = edgeMatch[1].length;
      current = {
        rawType: edgeMatch[2].trim(),
        targets: [],
        lineStart: i,
        lineEnd: i,
      };
      continue;
    }

    if (!current) continue;

    const trimmed = line.trim();
    const ql = getQuoteLevel(line);

    // End of the current edge block if quote level drops below the edge header level
    // (ignore blank lines)
    if (trimmed !== "" && ql < currentEdgeLevel) {
      flush(i - 1);
      continue;
    }

    // Collect targets (multiple per line allowed)
    TARGET_LINK_RE.lastIndex = 0;
    let m: RegExpExecArray | null;
    while ((m = TARGET_LINK_RE.exec(line)) !== null) {
      if (m[1]) {
        const t = m[1].trim();
        if (t) current.targets.push(t);
      }
    }
  }

  flush(lines.length - 1);
  return edges;
}