// Credential references (note section 2, addendum A section 7). A
// reference names where a token lives, never the token. The checks here use
// lstat and realpath only; nothing in this package opens a token file.

import { lstatSync, realpathSync } from "node:fs";
import { isAbsolute, normalize, relative, sep } from "node:path";
import { refuse } from "./errors.mjs";
import { SERVICES } from "./vocabulary.mjs";
import { requireObject, rejectUnknownKeys, requireDate } from "./util.mjs";

const ENV_NAME = /^[A-Z][A-Z0-9_]{0,63}$/;
const DATE_KEY = Object.freeze({ gitea: "rotateBy", vikunja: "expires" });
const WARN_DAYS = 7;
const DAY_MS = 24 * 60 * 60 * 1000;

// Shape check for one reference. Returns a frozen { service, file | env,
// rotateBy | expires }.
export function parseCredentialRef(ref, service, where) {
  if (!SERVICES.includes(service)) refuse(`${where}: unknown credential service ${JSON.stringify(service)}`);
  requireObject(ref, where);
  const dateKey = DATE_KEY[service];
  rejectUnknownKeys(ref, ["file", "env", dateKey], where);
  const hasFile = ref.file !== undefined;
  const hasEnv = ref.env !== undefined;
  if (hasFile === hasEnv) refuse(`${where} must name exactly one of "file" or "env"`);
  const out = { service };
  if (hasFile) {
    if (typeof ref.file !== "string" || !isAbsolute(ref.file) || normalize(ref.file) !== ref.file || ref.file.includes("\0")) {
      refuse(`${where}.file must be a normalized absolute path`);
    }
    out.file = ref.file;
  } else {
    if (typeof ref.env !== "string" || !ENV_NAME.test(ref.env)) refuse(`${where}.env must match ${ENV_NAME}`);
    out.env = ref.env;
  }
  if (ref[dateKey] === undefined) refuse(`${where} needs "${dateKey}" (YYYY-MM-DD)`);
  out[dateKey] = requireDate(ref[dateKey], `${where}.${dateKey}`);
  return Object.freeze(out);
}

function inside(root, path) {
  const rel = relative(root, path);
  return rel === "" || (!rel.startsWith(`..${sep}`) && rel !== ".." && !isAbsolute(rel));
}

// Check a parsed reference against the filesystem and the calendar.
// Returns { problems: [...], warnings: [...] }; a caller that finds any
// problem refuses. `forbiddenRoots` are directories a token file must not
// sit in (the repository, dataRoot). `now` is a Date.
export function checkCredentialRef(ref, { forbiddenRoots = [], now = new Date(), env = process.env, uid = process.getuid() } = {}) {
  const problems = [];
  const warnings = [];
  const label = `${ref.service} ${ref.file ? `file ${ref.file}` : `env ${ref.env}`}`;
  if (ref.file) {
    let stat = null;
    try {
      stat = lstatSync(ref.file);
    } catch {
      problems.push(`${label}: not found`);
    }
    if (stat) {
      if (stat.isSymbolicLink() || !stat.isFile()) problems.push(`${label}: must be a regular file, not a symbolic link`);
      else {
        if (stat.uid !== uid) problems.push(`${label}: owned by uid ${stat.uid}, not ${uid}`);
        if ((stat.mode & 0o077) !== 0) problems.push(`${label}: mode ${(stat.mode & 0o777).toString(8)} gives group or other access; use 600`);
        if (stat.size === 0) problems.push(`${label}: empty`);
        let real = ref.file;
        try {
          real = realpathSync(ref.file);
        } catch {
          problems.push(`${label}: path can't be resolved`);
        }
        for (const root of forbiddenRoots) {
          let realRoot = root;
          try {
            realRoot = realpathSync(root);
          } catch {
            // A root that doesn't exist yet can't contain the file.
          }
          if (inside(realRoot, real)) problems.push(`${label}: inside ${root}; token files live outside the repository and dataRoot`);
        }
      }
    }
  } else if (env[ref.env] === undefined || env[ref.env] === "") {
    warnings.push(`${label}: not set in this environment; the launcher must provide it`);
  }
  const days = (dateText) => Math.floor((Date.parse(`${dateText}T00:00:00Z`) - now.getTime()) / DAY_MS);
  if (ref.expires) {
    const left = days(ref.expires);
    if (Date.parse(`${ref.expires}T00:00:00Z`) <= now.getTime()) problems.push(`${label}: expired on ${ref.expires}`);
    else if (left < WARN_DAYS) warnings.push(`${label}: expires on ${ref.expires}`);
  }
  if (ref.rotateBy && Date.parse(`${ref.rotateBy}T00:00:00Z`) <= now.getTime()) {
    warnings.push(`${label}: rotation was due on ${ref.rotateBy}`);
  }
  return { problems, warnings };
}