MineGeo/shared/map-archive.ts

import { z } from "zod";
import { Unzip, UnzipInflate, strFromU8 } from "fflate";
import { boundsSchema, datasetSchema, faces } from "./protocol";

export const archiveLimit = 256 * 1024 * 1024;
export const archiveFileLimit = 50 * 1024 * 1024;
export const archiveManifestName = "minegeo-map.json";
const locationSchema = z.strictObject({
  id: z.string().regex(/^[a-zA-Z0-9_-]{1,64}$/),
  x: z.number().finite(),
  y: z.number().finite(),
  z: z.number().finite(),
});
export const archiveMetadataSchema = z.strictObject({
  format: z.literal("minegeo-map/v1"),
  minecraftVersion: datasetSchema.shape.minecraftVersion,
  dimension: z.literal("minecraft:overworld"),
  north: z.literal("-z"),
  source: z.enum(["plugin", "fabric"]),
  name: z.string().min(3).max(80),
  description: z.string().max(2000),
  serverName: z.string().min(2).max(80),
  bounds: boundsSchema,
  viewpoints: z.array(locationSchema).min(5).max(24),
  originalMapId: z.string().uuid(),
  originalOwner: z.string().min(1).max(200),
  signature: z.string().regex(/^[a-f0-9]{64}$/),
});
export const archiveSchema = archiveMetadataSchema
  .extend({
    assets: z
      .array(
        z.strictObject({
          path: z
            .string()
            .regex(
              /^(?:map\.webp|[a-zA-Z0-9_-]{1,64}\/(?:px|nx|py|ny|pz|nz)\.webp)$/,
            ),
          bytes: z.number().int().positive().max(archiveFileLimit),
          sha256: z.string().regex(/^[a-f0-9]{64}$/),
        }),
      )
      .min(31)
      .max(145),
  })
  .superRefine((archive, ctx) => {
    const paths = new Set(archive.assets.map((a) => a.path));
    const expected = [
      "map.webp",
      ...archive.viewpoints.flatMap((p) =>
        faces.map((f) => `${p.id}/${f}.webp`),
      ),
    ];
    if (
      paths.size !== archive.assets.length ||
      paths.size !== expected.length ||
      expected.some((p) => !paths.has(p))
    )
      ctx.addIssue({
        code: "custom",
        message:
          "The archive must contain the map and all six faces for each location",
      });
    if (
      new Set(archive.viewpoints.map((p) => p.id)).size !==
      archive.viewpoints.length
    )
      ctx.addIssue({ code: "custom", message: "Viewpoint IDs must be unique" });
    if (archive.assets.reduce((n, a) => n + a.bytes, 0) > archiveLimit)
      ctx.addIssue({
        code: "custom",
        message: "Map archive exceeds the 256 MB limit",
      });
    for (const p of archive.viewpoints)
      if (
        p.x < archive.bounds.minX ||
        p.x > archive.bounds.maxX ||
        p.z < archive.bounds.minZ ||
        p.z > archive.bounds.maxZ
      )
        ctx.addIssue({
          code: "custom",
          message: "Viewpoint outside map bounds",
        });
  });
export type MapArchive = z.infer<typeof archiveSchema>;
export type ArchiveMetadata = z.infer<typeof archiveMetadataSchema>;

// Strict portable metadata has no account IDs, original storage paths, server
// address, credentials, publication state, or contribution permissions.
export function importManifest(value: unknown) {
  const archive = archiveSchema.parse(value);
  return datasetSchema.parse({
    ...archive,
    format: "minegeo-dataset/v1",
    mediaFormat: "webp",
  });
}

export async function sha256(bytes: Uint8Array) {
  const digest = await crypto.subtle.digest(
    "SHA-256",
    new Uint8Array(bytes).buffer,
  );
  return Array.from(new Uint8Array(digest), (b) =>
    b.toString(16).padStart(2, "0"),
  ).join("");
}

export async function readMapArchive(bytes: Uint8Array) {
  if (!bytes.length || bytes.length > archiveLimit)
    throw new Error("Map archive exceeds the 256 MB limit");
  const files = new Map<string, Uint8Array>();
  const names = new Set<string>();
  let total = 0;
  let failure: Error | undefined;
  const unzip = new Unzip((file) => {
    const valid =
      file.name === archiveManifestName ||
      /^(?:map\.webp|[a-zA-Z0-9_-]{1,64}\/(?:px|nx|py|ny|pz|nz)\.webp)$/.test(
        file.name,
      );
    const max =
      file.name === archiveManifestName ? 128 * 1024 : archiveFileLimit;
    if (
      !valid ||
      names.has(file.name) ||
      names.size >= 146 ||
      (file.originalSize != null && file.originalSize > max)
    )
      throw new Error(
        "Invalid map ZIP: unexpected, duplicate, or oversized file",
      );
    names.add(file.name);
    const chunks: Uint8Array[] = [];
    let size = 0;
    file.ondata = (error, data, final) => {
      if (failure) return;
      if (error) {
        failure = error;
        file.terminate();
        return;
      }
      size += data.length;
      total += data.length;
      if (size > max || total > archiveLimit) {
        failure = new Error("Map archive exceeds the 256 MB limit");
        file.terminate();
        return;
      }
      chunks.push(data);
      if (final) {
        const content = new Uint8Array(size);
        let offset = 0;
        for (const chunk of chunks) {
          content.set(chunk, offset);
          offset += chunk.length;
        }
        files.set(file.name, content);
      }
    };
    file.start();
  });
  unzip.register(UnzipInflate);
  try {
    // Bound inflation per push even when a ZIP lies about its original sizes.
    for (let offset = 0; offset < bytes.length; offset += 1024) {
      unzip.push(
        bytes.subarray(offset, offset + 1024),
        offset + 1024 >= bytes.length,
      );
      if (failure) throw failure;
    }
  } catch (error) {
    throw new Error(error instanceof Error ? error.message : "Invalid map ZIP");
  }
  if (files.size !== names.size || !files.has(archiveManifestName))
    throw new Error("Invalid or incomplete map ZIP");
  let archive: MapArchive;
  try {
    archive = archiveSchema.parse(
      JSON.parse(strFromU8(files.get(archiveManifestName)!)),
    );
  } catch {
    throw new Error("This ZIP is not a supported MineGeo map");
  }
  if (files.size !== archive.assets.length + 1)
    throw new Error("Map ZIP contains unexpected files");
  for (const asset of archive.assets) {
    const content = files.get(asset.path);
    if (
      !content ||
      content.length !== asset.bytes ||
      (await sha256(content)) !== asset.sha256
    )
      throw new Error("Map archive checksum or size mismatch");
  }
  return { archive, files };
}