#!/usr/bin/env bun
// gstack-version-bump — deterministic version-state classifier + writer for /ship.
//
// Extracted from ship Step 12 prose (v2 plan T9, hybrid CLI extraction). The
// idempotency classification and the dual-write to VERSION + package.json are
// pure deterministic logic; running them as tested code removes the single
// worst /ship footgun — re-bumping an already-shipped branch — from prose the
// agent could skip or misread when the step lives in a lazy-loaded section.
//
// What STAYS agent judgment (NOT here): the bump-LEVEL decision (micro/patch vs
// minor/major, which may AskUserQuestion on feature signals) and the queue
// collision prompt. The slot pick itself is bin/gstack-next-version. This CLI
// only answers "what state am I in?" and "write this exact version".
//
// Subcommands:
//   classify --base <branch> [--version-path <p>]
//       Compares VERSION vs origin/<base>:VERSION vs package.json.version.
//       Emits JSON: { state, baseVersion, currentVersion, pkgVersion, pkgExists }
//       state ∈ FRESH | ALREADY_BUMPED | DRIFT_STALE_PKG | DRIFT_UNEXPECTED
//       Exit 0 on a decidable state (incl. DRIFT_UNEXPECTED — it's a real state
//       the caller must handle), exit 2 on bad args / unresolvable base.
//
//   write --version <X.Y.Z.W> [--version-path <p>]
//       Validates the 4-digit pattern, writes VERSION + package.json.version.
//       Use for the FRESH bump (or an approved queue rebump). Exit 3 on a
//       half-write (VERSION written, package.json failed) so the caller knows
//       drift exists; the next classify() will report DRIFT_STALE_PKG.
//
//   repair [--version-path <p>]
//       DRIFT_STALE_PKG path: sync package.json.version to the current VERSION
//       file. No bump. Validates the VERSION pattern first.
//
// Contract: classify NEVER writes. write/repair mutate VERSION + the manifest
// (+ its lockfile) only. No git mutation, no network. Mirrors
// gstack-next-version's reader/writer split so /ship composes them.
//
// Manifest resolution (all three subcommands accept --package-json-path):
//   --package-json-path <p>  →  .gstack/package-json-path  →  ./package.json
// A repo whose only Node package lives in a subdirectory (web/, app/,
// frontend/) has no ROOT package.json. The tool used to report
// pkgExists:false there and write VERSION alone, leaving the manifest to be
// bumped by hand — the drift this tool exists to prevent, in the one layout
// where it silently did nothing.
//
// npm semver: VERSION is 4-digit MAJOR.MINOR.PATCH.MICRO; npm rejects a
// fourth component. When a package-lock.json sits beside the manifest — proof
// npm actually manages it — the MICRO is dropped and the lockfile's two
// version fields are mirrored too. Without a lockfile nothing validates the
// field and the historical 1:1 mirror is preserved, so gstack's own
// package.json keeps carrying 1.60.1.0.

import { existsSync, readFileSync, writeFileSync } from "node:fs";
import { execFileSync } from "node:child_process";
import { dirname, join, relative } from "node:path";

const VERSION_RE = /^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$/;
const DEFAULT = "0.0.0.0";

type State = "FRESH" | "ALREADY_BUMPED" | "DRIFT_STALE_PKG" | "DRIFT_UNEXPECTED";

function fail(msg: string, code = 2): never {
  process.stderr.write(`gstack-version-bump: ${msg}\n`);
  process.exit(code);
}

function argVal(args: string[], flag: string): string | undefined {
  const i = args.indexOf(flag);
  return i >= 0 && i + 1 < args.length ? args[i + 1] : undefined;
}

/** Resolve the VERSION file path: --version-path, else .gstack/version-path, else "VERSION". */
function resolveVersionPath(cwd: string, explicit?: string): string {
  if (explicit) return join(cwd, explicit);
  const pin = join(cwd, ".gstack", "version-path");
  if (existsSync(pin)) {
    const p = readFileSync(pin, "utf-8").trim();
    if (p) return join(cwd, p);
  }
  return join(cwd, "VERSION");
}

function readVersionFile(p: string): string {
  try {
    const v = readFileSync(p, "utf-8").replace(/[\r\n\s]/g, "");
    return v || DEFAULT;
  } catch {
    return DEFAULT;
  }
}

/**
 * Resolve the package.json path: --package-json-path, else
 * .gstack/package-json-path, else "package.json".
 *
 * Mirrors resolveVersionPath. A repo whose only Node package lives in a
 * subdirectory (web/, app/, frontend/) has no ROOT package.json, so the
 * old join(cwd, "package.json") reported pkgExists:false and every bump
 * silently wrote VERSION alone — leaving the manifest to be edited by
 * hand, which is exactly the drift this tool exists to prevent.
 */
function resolvePkgPath(cwd: string, explicit?: string): string {
  if (explicit) return join(cwd, explicit);
  const pin = join(cwd, ".gstack", "package-json-path");
  if (existsSync(pin)) {
    const p = readFileSync(pin, "utf-8").trim();
    if (p) return join(cwd, p);
  }
  return join(cwd, "package.json");
}

/** The npm lockfile beside a manifest, or "" when there is none. */
function lockPathFor(pkgPath: string): string {
  const lock = join(dirname(pkgPath), "package-lock.json");
  return existsSync(lock) ? lock : "";
}

/**
 * The version string to write INTO a manifest.
 *
 * VERSION is 4-digit MAJOR.MINOR.PATCH.MICRO; npm's semver is 3-component
 * and rejects a fourth. A package-lock.json beside the manifest is proof
 * that npm actually manages it, so the MICRO is dropped there. Without a
 * lockfile nothing validates the field and the historical 1:1 mirror is
 * preserved — gstack's own package.json carries 1.60.1.0 and must keep
 * doing so.
 */
function manifestVersion(version: string, npmManaged: boolean): string {
  return npmManaged ? version.split(".").slice(0, 3).join(".") : version;
}

/** package.json version + existence, parsed without spawning node. */
function readPkgVersion(pkgPath: string): { exists: boolean; version: string } {
  if (!existsSync(pkgPath)) return { exists: false, version: "" };
  let raw: string;
  try {
    raw = readFileSync(pkgPath, "utf-8");
  } catch {
    return { exists: true, version: "" };
  }
  let parsed: unknown;
  try {
    parsed = JSON.parse(raw);
  } catch {
    fail(`${pkgPath} is not valid JSON. Fix the file before re-running /ship.`, 2);
  }
  const version = (parsed as { version?: unknown })?.version;
  return { exists: true, version: typeof version === "string" ? version : "" };
}

function writePkgVersion(pkgPath: string, version: string): void {
  const raw = readFileSync(pkgPath, "utf-8");
  const parsed = JSON.parse(raw) as Record<string, unknown>;
  parsed.version = version;
  writeFileSync(pkgPath, JSON.stringify(parsed, null, 2) + "\n");
}

/**
 * Mirror the manifest version into package-lock.json.
 *
 * npm records it twice — at the document root and again under
 * `packages[""]`, the entry describing the root package itself — and
 * `npm install` keeps both in step. Nothing else in a release does, so a
 * lockfile left behind drifts one field per bump until someone runs npm.
 * Pure JSON edit: no npm spawn, no dependency-tree churn.
 */
function writeLockVersion(lockPath: string, version: string): void {
  const parsed = JSON.parse(readFileSync(lockPath, "utf-8")) as Record<string, unknown>;
  parsed.version = version;
  const packages = parsed.packages as Record<string, { version?: string }> | undefined;
  if (packages && packages[""]) packages[""].version = version;
  writeFileSync(lockPath, JSON.stringify(parsed, null, 2) + "\n");
}

function baseVersion(cwd: string, base: string, versionRel: string): string {
  // Verify the base ref resolves, mirroring the Step 12 guard.
  try {
    execFileSync("git", ["rev-parse", "--verify", `origin/${base}`], { cwd, stdio: "ignore" });
  } catch {
    fail(`Unable to resolve origin/${base}. Run 'git fetch origin' or verify the base branch exists.`, 2);
  }
  try {
    const out = execFileSync("git", ["show", `origin/${base}:${versionRel}`], { cwd }).toString();
    const v = out.replace(/[\r\n\s]/g, "");
    return v || DEFAULT;
  } catch {
    // VERSION absent on base (new repo / new file) → treat as 0.0.0.0.
    return DEFAULT;
  }
}

/**
 * `expectedPkg` is what the manifest SHOULD hold for the current VERSION.
 * It defaults to VERSION itself (the historical 1:1 mirror), but for an
 * npm-managed manifest it is the 3-component truncation — otherwise a
 * correctly-synced `0.1.27` would be read as drift against `0.1.27.0`
 * forever, and every classify would return DRIFT.
 */
function classifyState(
  current: string,
  base: string,
  pkgExists: boolean,
  pkgVersion: string,
  expectedPkg: string = current,
): State {
  if (current === base) {
    // VERSION unchanged vs base. A diverging package.json means someone hand-edited
    // package.json bypassing /ship — unsafe to guess which is authoritative.
    if (pkgExists && pkgVersion && pkgVersion !== expectedPkg) return "DRIFT_UNEXPECTED";
    return "FRESH";
  }
  // VERSION already moved past base.
  if (pkgExists && pkgVersion && pkgVersion !== expectedPkg) return "DRIFT_STALE_PKG";
  return "ALREADY_BUMPED";
}

function cmdClassify(args: string[], cwd: string): void {
  const base = argVal(args, "--base");
  if (!base) fail("classify requires --base <branch>", 2);
  const versionPath = resolveVersionPath(cwd, argVal(args, "--version-path"));
  const versionRel = argVal(args, "--version-path") ?? "VERSION";
  const current = readVersionFile(versionPath);
  const baseV = baseVersion(cwd, base!, versionRel);
  const pkgPath = resolvePkgPath(cwd, argVal(args, "--package-json-path"));
  const pkg = readPkgVersion(pkgPath);
  const lockPath = pkg.exists ? lockPathFor(pkgPath) : "";
  const expectedPkg = manifestVersion(current, Boolean(lockPath));
  const state = classifyState(current, baseV, pkg.exists, pkg.version, expectedPkg);
  process.stdout.write(
    JSON.stringify({
      state,
      baseVersion: baseV,
      currentVersion: current,
      pkgVersion: pkg.version || null,
      pkgExists: pkg.exists,
      pkgPath: pkg.exists ? relative(cwd, pkgPath) : null,
      expectedPkgVersion: pkg.exists ? expectedPkg : null,
      lockfile: lockPath ? relative(cwd, lockPath) : null,
    }) + "\n",
  );
  // DRIFT_UNEXPECTED is a real, decidable state — the caller stops on it, but the
  // classification itself succeeded, so exit 0. (Bad args / unresolvable base are
  // the only exit-2 cases.)
}

function cmdWrite(args: string[], cwd: string): void {
  const version = argVal(args, "--version");
  if (!version) fail("write requires --version <X.Y.Z.W>", 2);
  if (!VERSION_RE.test(version!)) {
    fail(`NEW_VERSION (${version}) does not match MAJOR.MINOR.PATCH.MICRO. Aborting.`, 2);
  }
  const versionPath = resolveVersionPath(cwd, argVal(args, "--version-path"));
  const pkgPath = resolvePkgPath(cwd, argVal(args, "--package-json-path"));
  const hasPkg = existsSync(pkgPath);
  const lockPath = hasPkg ? lockPathFor(pkgPath) : "";
  writeFileSync(versionPath, version + "\n");
  if (hasPkg) {
    const manifestV = manifestVersion(version!, Boolean(lockPath));
    try {
      writePkgVersion(pkgPath, manifestV);
    } catch {
      fail(
        `failed to update ${relative(cwd, pkgPath)}. VERSION was written but the manifest is now stale. ` +
          "Re-run — classify will report DRIFT_STALE_PKG and repair will sync it.",
        3,
      );
    }
    if (lockPath) {
      try {
        writeLockVersion(lockPath, manifestV);
      } catch {
        fail(
          `failed to update ${relative(cwd, lockPath)}. VERSION and the manifest were written but ` +
            "the lockfile is now stale. Run `npm install --package-lock-only` in its directory.",
          3,
        );
      }
    }
  }
  process.stdout.write(
    JSON.stringify({
      wrote: version,
      packageJson: hasPkg,
      packageJsonPath: hasPkg ? relative(cwd, pkgPath) : null,
      packageJsonVersion: hasPkg ? manifestVersion(version!, Boolean(lockPath)) : null,
      lockfile: lockPath ? relative(cwd, lockPath) : null,
    }) + "\n",
  );
}

function cmdRepair(args: string[], cwd: string): void {
  const versionPath = resolveVersionPath(cwd, argVal(args, "--version-path"));
  const current = readVersionFile(versionPath);
  if (!VERSION_RE.test(current)) {
    fail(
      `VERSION file contents (${current}) do not match MAJOR.MINOR.PATCH.MICRO. ` +
        "Refusing to propagate invalid semver into package.json. Fix VERSION, then re-run /ship.",
      2,
    );
  }
  const pkgPath = resolvePkgPath(cwd, argVal(args, "--package-json-path"));
  if (!existsSync(pkgPath)) {
    fail(`repair: no package.json to sync (looked at ${relative(cwd, pkgPath)}).`, 2);
  }
  const lockPath = lockPathFor(pkgPath);
  const manifestV = manifestVersion(current, Boolean(lockPath));
  try {
    writePkgVersion(pkgPath, manifestV);
  } catch {
    fail(`drift repair failed — could not update ${relative(cwd, pkgPath)}.`, 3);
  }
  if (lockPath) {
    try {
      writeLockVersion(lockPath, manifestV);
    } catch {
      fail(`drift repair failed — could not update ${relative(cwd, lockPath)}.`, 3);
    }
  }
  process.stdout.write(
    JSON.stringify({
      repaired: current,
      packageJsonPath: relative(cwd, pkgPath),
      packageJsonVersion: manifestV,
      lockfile: lockPath ? relative(cwd, lockPath) : null,
    }) + "\n",
  );
}

// Exported for unit tests (pure logic, no I/O).
export { classifyState, VERSION_RE, type State };

if (import.meta.main) {
  const [sub, ...rest] = process.argv.slice(2);
  const cwd = process.cwd();
  switch (sub) {
    case "classify": cmdClassify(rest, cwd); break;
    case "write": cmdWrite(rest, cwd); break;
    case "repair": cmdRepair(rest, cwd); break;
    default:
      fail("usage: gstack-version-bump <classify|write|repair> [flags]", 2);
  }
}