// The MinIO admin client — minio's own code, living in the module (novox/hq ADR 0044). Ported out
// of the shared hal sdk, where a change to MinIO's surface rebuilt everything; here it rebuilds only
// minio. This module's tools, its provisioner and its events entrypoint import it; nothing outside
// minio does.
//
// It speaks two planes with node built-ins only (never the `minio` npm package):
//   - the S3 data plane over `fetch`, signed with AWS Signature V4 (node:crypto) — bucket and object
//     operations, and presigned URLs;
//   - the admin plane through the `mc` CLI (node:child_process) — scoped service accounts, whose
//     creation the MinIO admin REST API guards behind an encrypted payload `fetch` cannot form.
// This mirrors hal's MinIOClient/MinIOAdmin split, folded into one client the module builds from env.

import { createHash, createHmac } from "node:crypto";
import { execFile } from "node:child_process";
import { readFileSync, writeFileSync, unlinkSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { promisify } from "node:util";

const execFileAsync = promisify(execFile);

export interface MinioBucket {
  name: string;
  creationDate?: Date;
}

export interface MinioObject {
  name: string;
  size: number;
  lastModified: Date;
  etag?: string;
}

export interface MinioObjectStat {
  size: number;
  lastModified: Date;
  etag?: string;
  contentType?: string;
}

export interface MinioBucketInfo {
  name: string;
  exists: boolean;
  region: string;
  /** Sampled from the first page of a listing (up to 1000 keys) — a summary, not an audit. */
  sampledObjects: number;
  sampledBytes: number;
}

/** A scoped credential a consumer receives: an access key/secret pair confined to one bucket. */
export interface AccessKey {
  accessKey: string;
  secretKey: string;
}

interface MinioOptions {
  endpoint: string;
  rootUser: string;
  rootPassword: string;
  region: string;
  mcBin: string;
  mcConfigDir: string;
}

export class MinioClient {
  readonly baseUrl: string;
  readonly region: string;
  private readonly rootUser: string;
  private readonly rootPassword: string;
  private readonly mcBin: string;
  private readonly mcConfigDir: string;
  private aliasReady = false;

  constructor(opts: MinioOptions) {
    this.baseUrl = opts.endpoint.replace(/\/$/, "");
    this.region = opts.region;
    this.rootUser = opts.rootUser;
    this.rootPassword = opts.rootPassword;
    this.mcBin = opts.mcBin;
    this.mcConfigDir = opts.mcConfigDir;
  }

  /**
   * Build from the module's resolved environment. The endpoint and root identity come from
   * MESH_MINIO_*; the password may be given inline or as a mounted secret file (the manifest mounts
   * root.secret), so the provisioner container needs nothing written by hand. Throws when
   * unconfigured — an object store the module cannot reach is not a usable client.
   */
  static fromEnv(env: NodeJS.ProcessEnv = process.env): MinioClient {
    const endpoint = env.MESH_MINIO_ENDPOINT;
    const rootUser = env.MESH_MINIO_ROOT_USER;
    const passwordFile = env.MESH_MINIO_ROOT_PASSWORD_FILE;
    const rootPassword = env.MESH_MINIO_ROOT_PASSWORD ?? (passwordFile ? readFileSync(passwordFile, "utf8").trim() : undefined);
    if (!endpoint || !rootUser || !rootPassword) {
      throw new Error("minio is not configured — set MESH_MINIO_ENDPOINT, MESH_MINIO_ROOT_USER and MESH_MINIO_ROOT_PASSWORD");
    }
    return new MinioClient({
      endpoint,
      rootUser,
      rootPassword,
      region: env.MESH_MINIO_REGION ?? "us-east-1",
      mcBin: env.MESH_MINIO_MC_BIN ?? "mc",
      mcConfigDir: env.MESH_MINIO_MC_CONFIG ?? join(tmpdir(), ".mc-mesh"),
    });
  }

  // --- S3 data plane (signed fetch) ---------------------------------------

  async listBuckets(): Promise<MinioBucket[]> {
    const { status, text } = await this.request("GET", "/");
    if (status !== 200) throw new Error(`minio listBuckets: ${status} ${text}`);
    const out: MinioBucket[] = [];
    const re = /<Bucket>\s*<Name>([^<]+)<\/Name>\s*<CreationDate>([^<]*)<\/CreationDate>/g;
    let m: RegExpExecArray | null;
    while ((m = re.exec(text)) !== null) {
      out.push({ name: m[1], creationDate: m[2] ? new Date(m[2]) : undefined });
    }
    return out;
  }

  async bucketExists(bucket: string): Promise<boolean> {
    const { status } = await this.request("HEAD", `/${bucket}`);
    if (status === 200) return true;
    if (status === 404) return false;
    throw new Error(`minio bucketExists ${bucket}: ${status}`);
  }

  async createBucket(bucket: string): Promise<void> {
    const { status, text } = await this.request("PUT", `/${bucket}`);
    // 200 created; 409 BucketAlreadyOwnedByYou — idempotent, a re-provision must not fail.
    if (status !== 200 && status !== 409) throw new Error(`minio createBucket ${bucket}: ${status} ${text}`);
  }

  async removeBucket(bucket: string): Promise<void> {
    const { status, text } = await this.request("DELETE", `/${bucket}`);
    // 204 removed; 404 already gone — removal is idempotent too.
    if (status !== 204 && status !== 404) throw new Error(`minio removeBucket ${bucket}: ${status} ${text}`);
  }

  async listObjects(bucket: string, prefix = "", recursive = false, maxKeys = 100): Promise<MinioObject[]> {
    const query: Record<string, string> = { "list-type": "2", "max-keys": String(maxKeys) };
    if (prefix) query.prefix = prefix;
    if (!recursive) query.delimiter = "/";
    const { status, text } = await this.request("GET", `/${bucket}`, query);
    if (status !== 200) throw new Error(`minio listObjects ${bucket}: ${status} ${text}`);
    const out: MinioObject[] = [];
    for (const block of text.split("<Contents>").slice(1)) {
      const key = tag(block, "Key");
      if (!key) continue;
      out.push({
        name: key,
        size: Number(tag(block, "Size") ?? "0"),
        lastModified: new Date(tag(block, "LastModified") ?? 0),
        etag: tag(block, "ETag")?.replace(/&quot;|"/g, ""),
      });
    }
    return out;
  }

  async statObject(bucket: string, object: string): Promise<MinioObjectStat> {
    const { status, headers } = await this.request("HEAD", `/${bucket}/${object}`);
    if (status !== 200) throw new Error(`minio statObject ${bucket}/${object}: ${status}`);
    const lm = headers.get("last-modified");
    return {
      size: Number(headers.get("content-length") ?? "0"),
      lastModified: lm ? new Date(lm) : new Date(0),
      etag: headers.get("etag")?.replace(/"/g, "") ?? undefined,
      contentType: headers.get("content-type") ?? undefined,
    };
  }

  async bucketInfo(bucket: string): Promise<MinioBucketInfo> {
    const exists = await this.bucketExists(bucket);
    if (!exists) return { name: bucket, exists: false, region: this.region, sampledObjects: 0, sampledBytes: 0 };
    const objects = await this.listObjects(bucket, "", true, 1000);
    return {
      name: bucket,
      exists: true,
      region: this.region,
      sampledObjects: objects.length,
      sampledBytes: objects.reduce((n, o) => n + o.size, 0),
    };
  }

  /** A time-limited URL for GET (download) or PUT (upload) of one object — query-string SigV4. */
  presignedUrl(method: "GET" | "PUT", bucket: string, object: string, expires = 86400): string {
    const { amzDate, dateStamp } = this.stamp();
    const scope = `${dateStamp}/${this.region}/s3/aws4_request`;
    const host = new URL(this.baseUrl).host;
    const params: Record<string, string> = {
      "X-Amz-Algorithm": "AWS4-HMAC-SHA256",
      "X-Amz-Credential": `${this.rootUser}/${scope}`,
      "X-Amz-Date": amzDate,
      "X-Amz-Expires": String(expires),
      "X-Amz-SignedHeaders": "host",
    };
    const path = uriEncode(`/${bucket}/${object}`, false);
    const canonicalQuery = encodeQuery(params);
    const canonicalRequest = [method, path, canonicalQuery, `host:${host}\n`, "host", "UNSIGNED-PAYLOAD"].join("\n");
    const stringToSign = ["AWS4-HMAC-SHA256", amzDate, scope, sha256hex(canonicalRequest)].join("\n");
    const signature = hmac(this.signingKey(dateStamp), stringToSign).toString("hex");
    return `${this.baseUrl}${path}?${canonicalQuery}&X-Amz-Signature=${signature}`;
  }

  // --- admin plane (mc CLI) ------------------------------------------------

  /**
   * Create a service account scoped to one bucket, under a given access key and secret key, and
   * return the pair. The secret key is the mesh's — the mesh mints one password per consumer and
   * hands a copy to both ends (novox/hq ADR 0053), so minio sets that as the secret rather than
   * generating one the consumer could never learn. The MinIO admin REST API encrypts this request
   * with a key derived (Argon2) from the root secret, which node built-ins cannot reproduce — so, as
   * hal did, the module drives the `mc` CLI, which the runtime image bundles.
   */
  async createAccessKey(bucket: string, accessKey: string, secretKey: string): Promise<AccessKey> {
    await this.ensureAlias();
    const policyPath = join(this.mcConfigDir, `policy-${accessKey}.json`);
    writeFileSync(policyPath, bucketPolicy(bucket), { mode: 0o600 });
    try {
      await this.mc(
        "admin", "user", "svcacct", "add", "mesh", this.rootUser,
        "--access-key", accessKey,
        "--secret-key", secretKey,
        "--policy", policyPath,
      );
    } finally {
      try { unlinkSync(policyPath); } catch { /* best effort */ }
    }
    return { accessKey, secretKey };
  }

  async removeAccessKey(accessKey: string): Promise<void> {
    await this.ensureAlias();
    await this.mc("admin", "user", "svcacct", "rm", "mesh", accessKey);
  }

  private async ensureAlias(): Promise<void> {
    if (this.aliasReady) return;
    await this.mc("alias", "set", "mesh", this.baseUrl, this.rootUser, this.rootPassword);
    this.aliasReady = true;
  }

  private async mc(...args: string[]): Promise<string> {
    const { stdout } = await execFileAsync(this.mcBin, ["--config-dir", this.mcConfigDir, ...args], { timeout: 30_000 });
    return stdout.trim();
  }

  // --- SigV4 request plumbing ---------------------------------------------

  private async request(
    method: string,
    path: string,
    query: Record<string, string> = {},
  ): Promise<{ status: number; headers: Headers; text: string }> {
    const { amzDate, dateStamp } = this.stamp();
    const host = new URL(this.baseUrl).host;
    const payloadHash = sha256hex(""); // no request bodies are sent on this client
    const encodedPath = uriEncode(path, false);
    const canonicalQuery = encodeQuery(query);
    const signedHeaders = "host;x-amz-content-sha256;x-amz-date";
    const canonicalHeaders = `host:${host}\nx-amz-content-sha256:${payloadHash}\nx-amz-date:${amzDate}\n`;
    const canonicalRequest = [method, encodedPath, canonicalQuery, canonicalHeaders, signedHeaders, payloadHash].join("\n");
    const scope = `${dateStamp}/${this.region}/s3/aws4_request`;
    const stringToSign = ["AWS4-HMAC-SHA256", amzDate, scope, sha256hex(canonicalRequest)].join("\n");
    const signature = hmac(this.signingKey(dateStamp), stringToSign).toString("hex");
    const authorization = `AWS4-HMAC-SHA256 Credential=${this.rootUser}/${scope}, SignedHeaders=${signedHeaders}, Signature=${signature}`;

    const url = `${this.baseUrl}${encodedPath}${canonicalQuery ? `?${canonicalQuery}` : ""}`;
    const res = await fetch(url, {
      method,
      // `host` is set by fetch from the URL; the wire header matches what we signed.
      headers: { Authorization: authorization, "x-amz-content-sha256": payloadHash, "x-amz-date": amzDate },
    });
    const text = method === "HEAD" ? "" : await res.text();
    return { status: res.status, headers: res.headers, text };
  }

  private signingKey(dateStamp: string): Buffer {
    const kDate = hmac(`AWS4${this.rootPassword}`, dateStamp);
    const kRegion = hmac(kDate, this.region);
    const kService = hmac(kRegion, "s3");
    return hmac(kService, "aws4_request");
  }

  private stamp(): { amzDate: string; dateStamp: string } {
    const amzDate = new Date().toISOString().replace(/[:-]|\.\d{3}/g, "");
    return { amzDate, dateStamp: amzDate.slice(0, 8) };
  }
}

// --- module-scoped helpers -------------------------------------------------

/** A deterministic 20-char access key id from a consumer name, so removal needs no stored state:
 *  the provisioner recomputes the same id at teardown that it minted at creation. */
export function accessKeyFor(consumer: string): string {
  const chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
  const digest = createHash("sha256").update(consumer).digest();
  let out = "";
  for (let i = 0; i < 20; i++) out += chars[digest[i] % chars.length];
  return out;
}

/** A DNS-safe bucket name derived from a consumer — the removable identity of its storage. */
export function bucketFor(consumer: string): string {
  const name = consumer.toLowerCase().replace(/[^a-z0-9-]+/g, "-").replace(/^-+|-+$/g, "").slice(0, 63);
  return name.length >= 3 ? name : `mesh-${name}`;
}

function bucketPolicy(bucket: string): string {
  return JSON.stringify({
    Version: "2012-10-17",
    Statement: [{
      Effect: "Allow",
      Action: ["s3:*"],
      Resource: [`arn:aws:s3:::${bucket}`, `arn:aws:s3:::${bucket}/*`],
    }],
  });
}

function tag(xml: string, name: string): string | undefined {
  const m = new RegExp(`<${name}>([^<]*)</${name}>`).exec(xml);
  return m ? m[1] : undefined;
}

function hmac(key: Buffer | string, data: string): Buffer {
  return createHmac("sha256", key).update(data, "utf8").digest();
}

function sha256hex(data: string): string {
  return createHash("sha256").update(data, "utf8").digest("hex");
}

/** AWS canonical query: each key/value URI-encoded (slash included), sorted by encoded key. */
function encodeQuery(params: Record<string, string>): string {
  return Object.keys(params)
    .map((k) => [uriEncode(k, true), uriEncode(params[k], true)] as const)
    .sort((a, b) => (a[0] < b[0] ? -1 : a[0] > b[0] ? 1 : 0))
    .map(([k, v]) => `${k}=${v}`)
    .join("&");
}

/** RFC 3986 URI encoding, byte-correct via UTF-8. Path callers keep "/" literal; query callers don't. */
function uriEncode(str: string, encodeSlash: boolean): string {
  let out = "";
  for (const byte of Buffer.from(str, "utf8")) {
    const c = String.fromCharCode(byte);
    if (/[A-Za-z0-9_.~-]/.test(c)) out += c;
    else if (c === "/" && !encodeSlash) out += c;
    else out += "%" + byte.toString(16).toUpperCase().padStart(2, "0");
  }
  return out;
}