#!/usr/bin/env node
// ── Standalone API documentation generator ────────────────────────────────
//
// Reads all production .js files, extracts JSDoc /** ... */ comment blocks
// together with the declaration they annotate, and writes a formatted
// Markdown file to docs/API.md.
//
// Zero dependencies - uses only Node.js built-in fs and path.
// Run: node scripts/generate-docs.js
//
// ────────────────────────────────────────────────────────────────────────────

const fs = require("fs");
const path = require("path");

const SOURCE_DIR = ".";
const OUTPUT_FILE = path.join("docs", "API.md");
const SOURCE_GLOB = [
  "dom.js", "helpers.js", "error.js", "errno-data.js",
  "draw.js", "sections.js", "wcblock.js", "blocks-algo.js",
  "blocks-data.js", "blocks-proc.js", "wcprogram.js",
  "persist.js", "lib-loader.js", "proc-browser.js",
  "templates.js", "app.js"
];

// ── Parse helpers ────────────────────────────────────────────────────────

/** Extracts the first doc comment block preceding a declaration. */
function extractJSDoc(lines, startIdx) {
  let i = startIdx;
  while (i >= 0 && lines[i].trim() === "") i--;
  if (i < 0) return null;
  const line = lines[i].trim();
  if (!line.endsWith("*/")) return null;
  const end = i;
  while (i >= 0 && !lines[i].trim().startsWith("/**")) i--;
  if (i < 0) return null;
  const raw = lines.slice(i, end + 1).join("\n");
  return { raw, startLine: i + 1 };
}

/** Strips opening, closing, and leading star markers from a JSDoc block. */
function cleanJSDoc(raw) {
  const singleLine = !raw.includes("\n");
  if (singleLine) {
    return raw.replace(/^\/\*\*\s*/, "").replace(/\s*\*\/$/, "").trim();
  }
  return raw
    .replace(/^\/\*\*[\s\S]*?\n/, "")
    .replace(/\s*\*\/\s*$/, "")
    .split("\n")
    .map(l => l.replace(/^\s*\* ?/, ""))
    .join("\n")
    .trim();
}

/** Extracts the name from a declaration line like class Foo, function foo, or const foo. */
function declName(line) {
  const m = line.match(/^(?:class|function|const)\s+(\w+)/);
  return m ? m[1] : null;
}

/** Determines the declaration kind (class/function/const) from the line. */
function declKind(line) {
  if (/^class\b/.test(line)) return "class";
  if (/^function\b/.test(line)) return "function";
  if (/^const\b/.test(line)) return "const";
  return "declaration";
}

// ── Generator ────────────────────────────────────────────────────────────

function generate() {
  const blocks = [];

  for (const filename of SOURCE_GLOB) {
    const absPath = path.resolve(SOURCE_DIR, filename);
    if (!fs.existsSync(absPath)) {
      console.warn(`  [warn] ${filename} not found, skipping`);
      continue;
    }
    const src = fs.readFileSync(absPath, "utf-8");
    const lines = src.split("\n");

    for (let i = 0; i < lines.length; i++) {
      const line = lines[i];
      const name = declName(line);
      if (!name) continue;
      const jsdoc = extractJSDoc(lines, i - 1);
      if (!jsdoc) continue;
      const kind = declKind(line);
      const desc = cleanJSDoc(jsdoc.raw);

      // extract @param and @returns from the cleaned JSDoc
      const params = [];
      const returns = [];
      const descLines = desc.split("\n");
      const bodyLines = [];
      for (const dl of descLines) {
        const pm = dl.match(/^\s*@param\s+\{([^}]+)\}\s+(\S+)\s*(.*)/);
        const rm = dl.match(/^\s*@returns\s+\{([^}]+)\}\s*(.*)/);
        const tm = dl.match(/^\s*@type\s+\{([^}]+)\}\s*(.*)/);
        if (pm) params.push({ type: pm[1], name: pm[2], desc: pm[3] });
        else if (rm) returns.push({ type: rm[1], desc: rm[2] });
        else if (tm) bodyLines.push(`Type: \`${tm[1]}\` ${tm[2]}`);
        else bodyLines.push(dl);
      }

      const body = bodyLines.join("\n").trim();
      blocks.push({ filename, name, kind, line: i + 1, body, params, returns });
    }
  }

  // ── Write output ─────────────────────────────────────────────────────

  fs.mkdirSync(path.dirname(OUTPUT_FILE), { recursive: true });
  const out = fs.createWriteStream(OUTPUT_FILE);
  out.write("# API Reference\n\n");
  out.write(`Generated from JSDoc annotations in ${SOURCE_GLOB.length} source files.\n\n`);

  // Group by file
  let currentFile = "";
  for (const b of blocks) {
    if (b.filename !== currentFile) {
      currentFile = b.filename;
      out.write(`\n---\n## ${b.filename}\n\n`);
    }

    const anchor = `${b.kind}-${b.name}`;
    out.write(`### <a name="${anchor}"></a>\`${b.kind}\` ${b.name}  \n`);
    out.write(`*Line ${b.line}*\n\n`);

    if (b.body) out.write(b.body + "\n\n");

    if (b.params.length > 0) {
      out.write("**Parameters:**\n\n");
      out.write("| Name | Type | Description |\n");
      out.write("|------|------|------------|\n");
      for (const p of b.params) {
        out.write(`| \`${p.name}\` | \`${p.type}\` | ${p.desc} |\n`);
      }
      out.write("\n");
    }

    if (b.returns.length > 0) {
      out.write("**Returns:** ");
      for (const r of b.returns) {
        out.write(`\`${r.type}\` — ${r.desc}`);
      }
      out.write("\n\n");
    }
  }

  out.end();
  console.log(`Wrote ${OUTPUT_FILE} (${blocks.length} documented declarations)`);
}

generate();