#!/usr/bin/env node
// Renders the markdown body for the Bundle-Budget PR comment.
//
// Inputs:
//   --current <path>   JSON produced by `verify-bundle-size.mjs --json`
//   --baseline <path>  Optional baseline JSON from main branch (for Δ column).
//                      Missing/unreadable → Δ column shows "—".
//   --out <path>       Write rendered markdown here (default: bundle-comment.md)
//
// Output marker: the comment starts with `<!-- bundle-budget-report -->` so
// downstream upsert steps can identify and replace it without duplication.

import fs from "node:fs";

function parseArgs(argv) {
  const out = {};
  for (let i = 0; i < argv.length; i += 1) {
    const arg = argv[i];
    if (arg === "--current") out.current = argv[++i];
    else if (arg === "--baseline") out.baseline = argv[++i];
    else if (arg === "--out") out.out = argv[++i];
  }
  return out;
}

export function readReport(filePath) {
  if (!filePath) return null;
  try {
    if (!fs.existsSync(filePath)) return null;
    const raw = fs.readFileSync(filePath, "utf8");
    if (!raw.trim()) return null;
    return JSON.parse(raw);
  } catch {
    return null;
  }
}

const STATUS_BADGE = {
  ok: "[OK]",
  warning: "[WARN]",
  exceeds: "[EXCEED]",
  unbudgeted: "[?]",
};

const KIND_LABEL = {
  route: "route",
  vendor: "vendor",
};

export function formatKb(bytes) {
  if (typeof bytes !== "number") return "—";
  return `${(bytes / 1024).toFixed(1)} KB`;
}

export function formatDelta(currentBytes, baselineBytes) {
  if (typeof baselineBytes !== "number") return "—";
  const diff = currentBytes - baselineBytes;
  const sign = diff >= 0 ? "+" : "";
  return `${sign}${(diff / 1024).toFixed(1)} KB`;
}

export function indexBaseline(report) {
  const map = new Map();
  if (!report?.entries) return map;
  for (const e of report.entries) {
    map.set(e.key, e);
  }
  return map;
}

export function buildMarkdown(current, baseline) {
  const lines = [];
  lines.push("<!-- bundle-budget-report -->");
  lines.push("## Bundle Budget Report");
  lines.push("");
  if (!current || current.skipped) {
    lines.push("> No bundle artifacts measured (web build skipped or empty).");
    return lines.join("\n");
  }
  const totals = current.totals ?? { ok: 0, warning: 0, exceeds: 0, unbudgeted: 0 };
  lines.push(
    `**Summary:** ok=${totals.ok} - warning=${totals.warning} - exceeds=${totals.exceeds} - unbudgeted=${totals.unbudgeted}`,
  );
  lines.push("");
  if (totals.exceeds > 0) {
    lines.push(
      "> Some routes exceed their configured limit. This does **not** block the PR, but please check whether the growth is intentional.",
    );
    lines.push("");
  }

  const baselineIndex = indexBaseline(baseline);
  const entries = [...(current.entries ?? [])];
  // sort: exceeds → warning → unbudgeted → ok, then biggest first
  const rank = { exceeds: 0, warning: 1, unbudgeted: 2, ok: 3 };
  entries.sort((a, b) => {
    if (rank[a.status] !== rank[b.status]) return rank[a.status] - rank[b.status];
    return b.gzipSize - a.gzipSize;
  });

  lines.push("| Status | Kind | Route / Chunk | Size (gzip) | Limit | Δ from main |");
  lines.push("|---|---|---|---|---|---|");
  for (const e of entries) {
    const status = STATUS_BADGE[e.status] ?? e.status;
    const kind = KIND_LABEL[e.kind] ?? e.kind;
    const limit = typeof e.limitKb === "number" ? `${e.limitKb} KB` : "default";
    const base = baselineIndex.get(e.key);
    const delta = formatDelta(e.gzipSize, base?.gzipSize);
    lines.push(`| ${status} | ${kind} | \`${e.key}\` | ${formatKb(e.gzipSize)} | ${limit} | ${delta} |`);
  }
  lines.push("");
  lines.push("_Sizes are gzip-compressed. Budgets configured in `scripts/bundle-budgets.json`. Docs: `docs/architecture/bundle-budgets.md`._");
  return lines.join("\n");
}

async function main() {
  const args = parseArgs(process.argv.slice(2));
  if (!args.current) {
    console.error("Usage: render-bundle-budget-comment.mjs --current <path> [--baseline <path>] [--out <path>]");
    process.exit(2);
  }
  const current = readReport(args.current);
  const baseline = readReport(args.baseline);
  const md = buildMarkdown(current, baseline);
  const outPath = args.out ?? "bundle-comment.md";
  fs.writeFileSync(outPath, `${md}\n`, "utf8");
  // Also surface on stdout for log visibility.
  process.stdout.write(`${md}\n`);
}

const isMain = import.meta.url === `file://${process.argv[1]}`;
if (isMain) {
  main().catch((err) => {
    console.error(err);
    process.exit(1);
  });
}