#!/usr/bin/env node

/**
 * Opt-in, network-dependent URL audit. This is intentionally separate from
 * deterministic structural validation. Authentication, access-control and
 * rate-limit responses are reported as indeterminate, never as missing.
 */

import fs from "node:fs/promises";
import path from "node:path";
import { fileURLToPath } from "node:url";

const here = path.dirname(fileURLToPath(import.meta.url));
const root = path.resolve(here, "..");
const dataDir = path.resolve(process.argv[2] || path.join(root, "data"));
const TIMEOUT_MS = 15_000;
const CONCURRENCY = 6;

function parseCsv(text, filename) {
  const records = [];
  let record = [];
  let field = "";
  let quoted = false;
  for (let index = 0; index < text.length; index += 1) {
    const char = text[index];
    if (quoted) {
      if (char === '"' && text[index + 1] === '"') { field += '"'; index += 1; }
      else if (char === '"') quoted = false;
      else field += char;
    } else if (char === '"' && field === "") quoted = true;
    else if (char === ",") { record.push(field); field = ""; }
    else if (char === "\n") { record.push(field.replace(/\r$/, "")); records.push(record); record = []; field = ""; }
    else field += char;
  }
  if (quoted) throw new Error(`${filename}: unclosed CSV quote`);
  if (field || record.length) { record.push(field.replace(/\r$/, "")); records.push(record); }
  const headers = records.shift() || [];
  return records.filter((row) => row.some(Boolean)).map((values) =>
    Object.fromEntries(headers.map((header, index) => [header, values[index] ?? ""]))
  );
}

async function load(name) {
  return parseCsv(await fs.readFile(path.join(dataDir, `${name}.csv`), "utf8"), name);
}

const sourceRows = await load("sources");
const officialRows = await load("official_data_sources");
const claimEvidenceRows = await load("claim_evidence");
const claimCodedSourceIds = new Set(claimEvidenceRows.map((row) => row.source_id).filter(Boolean));
const links = [
  ...sourceRows.map((row) => ({
    table: "sources", row_id: row.source_id, url: row.url,
    claim_coded_scope: claimCodedSourceIds.has(row.source_id)
  })),
  ...officialRows.map((row) => ({
    table: "official_data_sources", row_id: row.official_source_id,
    url: row.landing_url || row.url, claim_coded_scope: false
  }))
];

function classify(status) {
  if (status === 404 || status === 410) return "confirmed_missing";
  if ([401, 403, 407, 429].includes(status)) return "indeterminate_access_control";
  if (status >= 200 && status < 400) return "reachable";
  return "indeterminate_http";
}

async function request(link) {
  let parsed;
  try {
    parsed = new URL(link.url);
    if (!/^https?:$/.test(parsed.protocol)) throw new Error("unsupported protocol");
  } catch (caught) {
    return { ...link, status: null, classification: "malformed_url", detail: caught.message };
  }
  try {
    const fetchOnce = async (range) => {
      const response = await fetch(parsed, {
        method: "GET",
        redirect: "follow",
        signal: AbortSignal.timeout(TIMEOUT_MS),
        headers: {
          ...(range ? { Range: "bytes=0-0" } : { "Cache-Control": "no-cache" }),
          "User-Agent": "agency-transfer-link-audit/0.4.0"
        }
      });
      await response.body?.cancel();
      return response;
    };
    const response = await fetchOnce(true);
    if ([404, 410].includes(response.status)) {
      try {
        const confirmation = await fetchOnce(false);
        if (![404, 410].includes(confirmation.status)) {
          return {
            ...link, status: confirmation.status, classification: classify(confirmation.status),
            final_url: confirmation.url, detail: `Initial ranged request returned ${response.status}; plain GET did not confirm it`
          };
        }
        return {
          ...link, status: confirmation.status, classification: "confirmed_missing",
          final_url: confirmation.url, confirmation: "two independent GET requests returned HTTP 404/410"
        };
      } catch (caught) {
        return {
          ...link, status: response.status, classification: "indeterminate_unconfirmed_missing",
          final_url: response.url, detail: `Initial ${response.status} could not be confirmed: ${String(caught.message || caught)}`
        };
      }
    }
    return {
      ...link,
      status: response.status,
      classification: classify(response.status),
      final_url: response.url
    };
  } catch (caught) {
    return { ...link, status: null, classification: "indeterminate_network", detail: String(caught.message || caught) };
  }
}

const results = new Array(links.length);
let cursor = 0;
async function worker() {
  while (cursor < links.length) {
    const index = cursor;
    cursor += 1;
    results[index] = await request(links[index]);
  }
}
await Promise.all(Array.from({ length: Math.min(CONCURRENCY, links.length) }, worker));

results.sort((a, b) => a.table.localeCompare(b.table) || a.row_id.localeCompare(b.row_id));
const blocking = results.filter(
  (item) => item.claim_coded_scope && ["malformed_url", "confirmed_missing"].includes(item.classification)
);
const counts = Object.fromEntries([...new Set(results.map((item) => item.classification))].sort().map((label) => [
  label,
  results.filter((item) => item.classification === label).length
]));
const report = {
  auditor: "agency-transfer-election-cases-v0.4.0/audit-links",
  checked_at: new Date().toISOString(),
  status: blocking.length ? "fail" : "pass",
  policy: "Only malformed URLs and twice-confirmed HTTP 404/410 responses in claim-coded evidence block; other corpus layers are advisory, and 401/403/407/429 or network failures are indeterminate.",
  checked_url_count: results.length,
  counts,
  results
};
process.stdout.write(`${JSON.stringify(report, null, 2)}\n`);
if (blocking.length) process.exitCode = 1;