import { CdnClient, CdnError, type FileInfo } from '@source/cdn';
import { AppError } from './errors.js';

const DEFAULT_PLUGIN_BUCKET = 'gamepanel-plugin-artifacts';
const DEFAULT_ARTIFACT_ACCESS_TTL_SECONDS = 900;
const ARTIFACT_POINTER_PREFIX = 'cdn://file/';

let cachedClient: CdnClient | null = null;
let cachedFingerprint: string | null = null;

function envValue(name: string): string | null {
  const value = process.env[name];
  if (!value) return null;
  const trimmed = value.trim();
  return trimmed.length > 0 ? trimmed : null;
}

function getCdnConfig(): { baseUrl: string; apiKey: string } | null {
  const baseUrl = envValue('CDN_BASE_URL');
  const apiKey = envValue('CDN_API_KEY');
  if (!baseUrl || !apiKey) return null;
  return { baseUrl, apiKey };
}

function getArtifactAccessTtlSeconds(): number {
  const raw = Number(
    process.env.CDN_PLUGIN_ARTIFACT_TTL_SECONDS ?? DEFAULT_ARTIFACT_ACCESS_TTL_SECONDS,
  );
  if (!Number.isFinite(raw) || raw <= 0) return DEFAULT_ARTIFACT_ACCESS_TTL_SECONDS;
  return Math.floor(raw);
}

function getOrCreateClient(): CdnClient | null {
  const config = getCdnConfig();
  if (!config) return null;

  const fingerprint = `${config.baseUrl}::${config.apiKey}`;
  if (cachedClient && cachedFingerprint === fingerprint) return cachedClient;

  cachedClient = new CdnClient({
    baseUrl: config.baseUrl,
    apiKey: config.apiKey,
    timeoutMs: 45_000,
    retry: {
      retries: 2,
      retryDelayMs: 250,
      maxRetryDelayMs: 2_000,
    },
  });
  cachedFingerprint = fingerprint;
  return cachedClient;
}

function requireClient(): CdnClient {
  const client = getOrCreateClient();
  if (!client) {
    throw new AppError(
      500,
      'CDN configuration is missing. Set CDN_BASE_URL and CDN_API_KEY.',
      'CDN_NOT_CONFIGURED',
    );
  }
  return client;
}

function toCdnAppError(error: unknown, fallbackMessage: string, fallbackCode: string): AppError {
  if (error instanceof AppError) return error;
  if (error instanceof CdnError) {
    return new AppError(502, `CDN error: ${error.message}`, fallbackCode);
  }
  return new AppError(502, fallbackMessage, fallbackCode);
}

export function getPluginBucketName(): string {
  return envValue('CDN_PLUGIN_BUCKET') ?? DEFAULT_PLUGIN_BUCKET;
}

export async function ensurePrivatePluginBucket(): Promise<string> {
  const client = requireClient();
  const bucketName = getPluginBucketName();

  try {
    const bucket = await client.getBucket(bucketName);
    if (bucket.isPublic) {
      await client.updateBucket(bucketName, { isPublic: false });
    }
    return bucketName;
  } catch (error) {
    if (error instanceof CdnError && error.statusCode === 404) {
      try {
        await client.createBucket(bucketName, {
          description: 'GamePanel plugin artifacts',
          isPublic: false,
        });
        return bucketName;
      } catch (createError) {
        throw toCdnAppError(
          createError,
          'Failed to create CDN plugin bucket',
          'CDN_BUCKET_CREATE_FAILED',
        );
      }
    }

    throw toCdnAppError(error, 'Failed to fetch CDN plugin bucket', 'CDN_BUCKET_READ_FAILED');
  }
}

export function buildCdnArtifactPointer(fileId: string): string {
  return `${ARTIFACT_POINTER_PREFIX}${fileId}`;
}

export function parseCdnArtifactPointer(value: string): string | null {
  const trimmed = value.trim();
  if (!trimmed) return null;

  if (trimmed.startsWith(ARTIFACT_POINTER_PREFIX)) {
    const id = trimmed.slice(ARTIFACT_POINTER_PREFIX.length).trim();
    return id.length > 0 ? id : null;
  }

  try {
    const parsed = new URL(trimmed);
    if (parsed.protocol === 'cdn:' && parsed.hostname === 'file') {
      const candidate = parsed.pathname.replace(/^\/+/, '').trim();
      return candidate.length > 0 ? candidate : null;
    }
  } catch {
    return null;
  }

  return null;
}

export async function uploadPluginArtifact(
  content: Uint8Array,
  filename: string,
  metadata: Record<string, unknown> = {},
): Promise<{ bucket: string; file: FileInfo; artifactPointer: string }> {
  const client = requireClient();
  const bucket = await ensurePrivatePluginBucket();

  try {
    const file = await client.upload(content, {
      bucket,
      filename,
      metadata,
    });

    return {
      bucket,
      file,
      artifactPointer: buildCdnArtifactPointer(file.id),
    };
  } catch (error) {
    throw toCdnAppError(error, 'Failed to upload artifact to CDN', 'CDN_UPLOAD_FAILED');
  }
}

export async function resolveArtifactDownloadUrl(artifactUrl: string): Promise<string> {
  const fileId = parseCdnArtifactPointer(artifactUrl);
  if (!fileId) return artifactUrl;

  const client = requireClient();
  const config = getCdnConfig();
  const ttl = getArtifactAccessTtlSeconds();

  try {
    const access = await client.getFileAccessUrl(fileId, ttl);
    if (!access.url || typeof access.url !== 'string') {
      throw new AppError(502, 'CDN access URL is empty', 'CDN_ACCESS_URL_EMPTY');
    }

    const resolvedUrl = access.url.trim();
    if (!resolvedUrl) {
      throw new AppError(502, 'CDN access URL is empty', 'CDN_ACCESS_URL_EMPTY');
    }

    if (/^https?:\/\//i.test(resolvedUrl)) {
      return resolvedUrl;
    }

    if (!config) {
      throw new AppError(
        500,
        'CDN configuration is missing. Set CDN_BASE_URL and CDN_API_KEY.',
        'CDN_NOT_CONFIGURED',
      );
    }

    return new URL(resolvedUrl, config.baseUrl).toString();
  } catch (error) {
    throw toCdnAppError(error, 'Failed to get temporary CDN access URL', 'CDN_ACCESS_URL_FAILED');
  }
}