export const WASM_MODULE_MANIFEST_SCHEMA = 1 as const;

export type WasmModuleLifecycle = "complete" | "debug";
export type WasmModuleVariant = "single" | "pthread";

export interface WasmModuleResource {
  fileName: string;
  url: string;
  sha256: string;
}

export interface WasmModuleEntry {
  id: string;
  lifecycle: WasmModuleLifecycle;
  preload: boolean;
  resources: Record<WasmModuleVariant, WasmModuleResource>;
}

export interface WasmModuleManifest {
  schemaVersion: typeof WASM_MODULE_MANIFEST_SCHEMA;
  releaseId: string;
  modules: WasmModuleEntry[];
}

const SHA256 = /^[a-f0-9]{64}$/;
const NAME = /^[A-Za-z0-9][A-Za-z0-9._-]{0,127}$/;

function record(value: unknown): value is Record<string, unknown> {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}

function resource(value: unknown, path: string): WasmModuleResource {
  if (!record(value) || typeof value.fileName !== "string" || !NAME.test(value.fileName) || !value.fileName.endsWith(".wasm") ||
      typeof value.url !== "string" || !value.url.startsWith("/") || /[?#\\]/.test(value.url) ||
      typeof value.sha256 !== "string" || !SHA256.test(value.sha256)) {
    throw new Error(`WASM_MODULE_MANIFEST_INVALID: ${path}`);
  }
  const segments = value.url.slice(1).split("/");
  if (segments.some((segment) => !NAME.test(segment)) || segments.at(-1) !== value.fileName) {
    throw new Error(`WASM_MODULE_MANIFEST_INVALID: ${path}.url`);
  }
  return { fileName: value.fileName, url: value.url, sha256: value.sha256 };
}

export function validateWasmModuleManifest(value: unknown): WasmModuleManifest {
  if (!record(value) || value.schemaVersion !== WASM_MODULE_MANIFEST_SCHEMA || typeof value.releaseId !== "string" || !NAME.test(value.releaseId) || !Array.isArray(value.modules)) {
    throw new Error("WASM_MODULE_MANIFEST_INVALID");
  }
  const ids = new Set<string>();
  const modules = value.modules.map((entry, index): WasmModuleEntry => {
    if (!record(entry) || typeof entry.id !== "string" || !NAME.test(entry.id) || ids.has(entry.id) ||
        (entry.lifecycle !== "complete" && entry.lifecycle !== "debug") || typeof entry.preload !== "boolean" ||
        !record(entry.resources) || !entry.resources.single || !entry.resources.pthread) {
      throw new Error(`WASM_MODULE_MANIFEST_INVALID: modules[${index}]`);
    }
    ids.add(entry.id);
    if (entry.lifecycle === "debug" && entry.preload) throw new Error(`WASM_MODULE_MANIFEST_INVALID: modules[${index}].preload`);
    return {
      id: entry.id,
      lifecycle: entry.lifecycle,
      preload: entry.preload,
      resources: {
        single: resource(entry.resources.single, `modules[${index}].resources.single`),
        pthread: resource(entry.resources.pthread, `modules[${index}].resources.pthread`),
      },
    };
  });
  return { schemaVersion: WASM_MODULE_MANIFEST_SCHEMA, releaseId: value.releaseId, modules };
}