import fs from "node:fs";
import path from "node:path";
import process from "node:process";

import { parse } from "@mermaid-js/parser";

function isMarkdownFile(filePath) {
  const lower = filePath.toLowerCase();
  return lower.endsWith(".md") || lower.endsWith(".markdown");
}

function* walkFiles(rootPath) {
  const stat = fs.statSync(rootPath);
  if (stat.isFile()) {
    yield rootPath;
    return;
  }

  const entries = fs.readdirSync(rootPath, { withFileTypes: true });
  for (const ent of entries) {
    const full = path.join(rootPath, ent.name);
    if (ent.isDirectory()) {
      yield* walkFiles(full);
    } else if (ent.isFile()) {
      yield full;
    }
  }
}

function extractMermaidBlocks(markdownText) {
  const blocks = [];
  const re = /```mermaid\s*([\s\S]*?)```/g;
  let m;
  while ((m = re.exec(markdownText)) !== null) {
    blocks.push(m[1] || "");
  }
  return blocks;
}

function detectDiagramType(code) {
  const lines = String(code || "")
    .replace(/\r\n?/g, "\n")
    .split("\n")
    .map((l) => l.trim())
    .filter((l) => l && !l.startsWith("%%"));

  if (!lines.length) return null;
  const head = lines[0];

  if (head.startsWith("pie")) return "pie";
  if (head.startsWith("gitGraph")) return "gitGraph";
  if (head.startsWith("architecture")) return "architecture";
  if (head.startsWith("packet")) return "packet";
  if (head.startsWith("info")) return "info";
  if (head.startsWith("radar")) return "radar";
  if (head.startsWith("treemap")) return "treemap";

  // Not supported by @mermaid-js/parser yet (example: flowchart/sequence/class).
  return null;
}

async function main() {
  const args = process.argv.slice(2);
  const roots = args.length ? args : ["reports"];

  let ok = true;
  let total = 0;
  let failures = 0;
  let skipped = 0;

  for (const root of roots) {
    for (const filePath of walkFiles(root)) {
      if (!isMarkdownFile(filePath)) continue;

      const text = fs.readFileSync(filePath, "utf8");
      const blocks = extractMermaidBlocks(text);
      if (!blocks.length) continue;

      for (let i = 0; i < blocks.length; i++) {
        const code = String(blocks[i] || "").trim();
        total += 1;
        const diagramType = detectDiagramType(code);
        if (!diagramType) {
          skipped += 1;
          continue;
        }
        try {
          await parse(diagramType, code);
        } catch (err) {
          ok = false;
          failures += 1;
          const msg =
            err && typeof err === "object" && "message" in err ? String(err.message) : String(err);
          console.error(`[mermaid] ${filePath} block=${i + 1} type=${diagramType}: ${msg}`);
        }
      }
    }
  }

  if (ok) {
    console.log(JSON.stringify({ ok: true, diagrams: total, skipped }, null, 2));
    return 0;
  }

  console.error(JSON.stringify({ ok: false, diagrams: total, failures, skipped }, null, 2));
  return 1;
}

process.exitCode = await main();