import type { MarketplaceResolveItem } from './account-plugin-cache';
import type { MarketplacePackageClientPort, PluginPackageStore } from './package-store';

const PLUGIN_ID_PATTERN = /^[a-z][a-z0-9.-]{0,127}$/u;
const RELEASE_ID_PATTERN = /^[A-Za-z0-9][A-Za-z0-9._-]{0,127}$/u;
const REQUEST_ID_PATTERN = /^[\x21-\x7e]{1,128}$/u;
const SHA256_PATTERN = /^[a-f0-9]{64}$/u;

export interface HostedAdmissionWorkerSnapshot {
  /** Main-issued identity for the logical worker operation. */
  readonly requestId: string;
  /** Release frozen into this parent worker's effective snapshot. */
  readonly pluginReleaseId?: string;
}

export interface MarketplaceHostedAdmissionInput {
  readonly pluginId: string;
  readonly workerSnapshot: HostedAdmissionWorkerSnapshot;
}

export interface MarketplaceHostedAdmission {
  readonly releaseId: string;
  readonly releaseAdmissionId: string;
}

export type MarketplaceHostedAdmissionErrorCode =
  | 'plugin_release_unavailable'
  | 'plugin_runtime_stale'
  | 'plugin_account_changed'
  | 'plugin_backend_unavailable';

export class MarketplaceHostedAdmissionError extends Error {
  constructor(
    readonly code: MarketplaceHostedAdmissionErrorCode,
    readonly status: number,
    readonly retryable: boolean,
    message: string,
  ) {
    super(message);
    this.name = 'MarketplaceHostedAdmissionError';
  }
}

export interface MarketplaceHostedAdmissionResolverOptions {
  readonly packageStore: Pick<PluginPackageStore, 'getInstalledRelease'>;
  readonly marketplace: Pick<MarketplacePackageClientPort, 'resolve'>;
  readonly makeloreVersion: string;
  readonly bundledReleases?: Readonly<Record<string, BundledHostedRelease>>;
}

export interface BundledHostedRelease {
  readonly releaseId: string;
  readonly version: string;
  readonly channel: 'stable';
}

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

function errorCode(value: unknown): unknown {
  return isRecord(value) ? value.code : undefined;
}

function releaseId(value: unknown): string | null {
  return typeof value === 'string' && RELEASE_ID_PATTERN.test(value) ? value : null;
}

function pluginId(value: unknown): string | null {
  return typeof value === 'string' && PLUGIN_ID_PATTERN.test(value) ? value : null;
}

function requestId(value: unknown): string | null {
  return typeof value === 'string' && REQUEST_ID_PATTERN.test(value) ? value : null;
}

function stale(message: string): MarketplaceHostedAdmissionError {
  return new MarketplaceHostedAdmissionError('plugin_runtime_stale', 409, false, message);
}

function unavailable(message: string): MarketplaceHostedAdmissionError {
  return new MarketplaceHostedAdmissionError('plugin_release_unavailable', 409, false, message);
}

function backendUnavailable(): MarketplaceHostedAdmissionError {
  return new MarketplaceHostedAdmissionError(
    'plugin_backend_unavailable',
    503,
    true,
    'Hosted Plugin admission service is temporarily unavailable',
  );
}

function accountChanged(): MarketplaceHostedAdmissionError {
  return new MarketplaceHostedAdmissionError(
    'plugin_account_changed',
    409,
    false,
    'Marketplace account changed while resolving hosted Plugin admission',
  );
}

function matchesFrozenRelease(
  item: MarketplaceResolveItem,
  installed: Awaited<ReturnType<PluginPackageStore['getInstalledRelease']>>,
  plugin: string,
): item is MarketplaceResolveItem & {
  readonly releaseId: string;
  readonly releaseAdmissionId: string;
} {
  if (!installed) return false;
  if (item.pluginId !== plugin || (item.action !== 'keep' && item.action !== 'install')) return false;
  if (releaseId(item.releaseId) !== installed.releaseId
    || releaseId(item.releaseAdmissionId) === null
    || item.releaseAdmissionId === undefined
    || item.releaseAdmissionId === null) return false;
  if (item.version !== installed.version || item.sha256 !== installed.sha256) return false;
  if (item.sizeBytes !== installed.sizeBytes || item.channel !== installed.channel) return false;
  return item.sha256 !== null && item.sha256 !== undefined && SHA256_PATTERN.test(item.sha256);
}

function matchesBundledFrozenRelease(
  item: MarketplaceResolveItem,
  bundled: BundledHostedRelease,
  plugin: string,
): item is MarketplaceResolveItem & {
  readonly releaseId: string;
  readonly releaseAdmissionId: string;
} {
  return item.pluginId === plugin
    && item.action === 'keep'
    && releaseId(item.releaseId) === bundled.releaseId
    && item.version === bundled.version
    && item.channel === bundled.channel
    && releaseId(item.releaseAdmissionId) !== null
    && item.sha256 == null
    && item.sizeBytes == null;
}

/**
 * Resolves the current account admission for the exact Release frozen into a
 * parent worker.  Marketplace identity and Release freshness are the only
 * concerns here; provider, payload, billing, and transport routes remain
 * outside this boundary.
 */
export class MarketplaceHostedAdmissionResolver {
  constructor(private readonly options: MarketplaceHostedAdmissionResolverOptions) {}

  async resolve(input: MarketplaceHostedAdmissionInput): Promise<MarketplaceHostedAdmission> {
    const plugin = pluginId(input?.pluginId);
    const worker = input?.workerSnapshot;
    const request = requestId(worker?.requestId);
    const frozenRelease = releaseId(worker?.pluginReleaseId);
    if (!plugin || !request) throw unavailable('Hosted Plugin worker identity is unavailable');
    if (!frozenRelease) throw unavailable('Hosted Plugin worker Release is unavailable');

    const bundled = this.options.bundledReleases?.[plugin];
    let installed: Awaited<ReturnType<PluginPackageStore['getInstalledRelease']>> = null;
    if (bundled) {
      if (releaseId(bundled.releaseId) !== frozenRelease || bundled.channel !== 'stable') {
        throw unavailable('Bundled hosted Plugin Release is unavailable');
      }
    } else {
      try {
        installed = await this.options.packageStore.getInstalledRelease(plugin, frozenRelease);
      } catch (error) {
        throw this.mapError(error);
      }
      if (!installed || installed.pluginId !== plugin || installed.releaseId !== frozenRelease
        || installed.unavailableReason || !installed.channel) {
        throw unavailable('Installed hosted Plugin Release is unavailable');
      }
    }

    let resolved;
    try {
      resolved = await this.options.marketplace.resolve({
        resolveRequestId: request,
        makeloreVersion: this.options.makeloreVersion,
        channel: bundled?.channel ?? installed?.channel ?? 'stable',
        installed: bundled ? [] : [{
          pluginId: installed!.pluginId,
          releaseId: installed!.releaseId,
          sha256: installed!.sha256,
        }],
      });
    } catch (error) {
      throw this.mapError(error);
    }

    if (resolved.stale || resolved.resolveRequestId !== request) {
      throw stale('Hosted Plugin worker admission is stale');
    }
    const item = resolved.items.find(({ pluginId: candidate }) => candidate === plugin);
    if (item?.action === 'unavailable') {
      throw unavailable('Hosted Plugin Release is unavailable');
    }
    const matches = item && (bundled
      ? matchesBundledFrozenRelease(item, bundled, plugin)
      : matchesFrozenRelease(item, installed, plugin));
    if (!matches) {
      throw stale('Hosted Plugin worker Release admission is stale');
    }
    return Object.freeze({
      releaseId: item.releaseId,
      releaseAdmissionId: item.releaseAdmissionId,
    });
  }

  private mapError(error: unknown): MarketplaceHostedAdmissionError {
    if (error instanceof MarketplaceHostedAdmissionError) return error;
    const code = errorCode(error);
    if (code === 'marketplace_account_changed' || code === 'plugin_account_changed') return accountChanged();
    return backendUnavailable();
  }
}

export function createMarketplaceHostedAdmissionResolver(
  options: MarketplaceHostedAdmissionResolverOptions,
): MarketplaceHostedAdmissionResolver {
  return new MarketplaceHostedAdmissionResolver(options);
}