/**
 * Product Asset Utilities — Download images, datasheets, manuals
 *
 * Handles downloading product assets from vendor websites,
 * storing them locally, and updating the database.
 */
import { pool } from "./db";
import { createHash } from "crypto";
import { writeFile, mkdir } from "fs/promises";
import { join, basename, extname } from "path";
import { existsSync } from "fs";

const ASSETS_DIR = process.env.ASSETS_DIR || join(__dirname, "..", "..", "..", "..", "assets");
const IMAGES_DIR = join(ASSETS_DIR, "images");
const DATASHEETS_DIR = join(ASSETS_DIR, "datasheets");
const MANUALS_DIR = join(ASSETS_DIR, "manuals");

async function ensureDir(dir: string): Promise<void> {
  if (!existsSync(dir)) {
    await mkdir(dir, { recursive: true });
  }
}

function contentHash(data: Buffer): string {
  return createHash("sha256").update(data).digest("hex").slice(0, 16);
}

function sanitizeFilename(name: string): string {
  return name.toLowerCase().replace(/[^a-z0-9.-]+/g, "-").replace(/^-|-$/g, "");
}

export interface AssetDownloadResult {
  localPath: string;
  hash: string;
  sizeBytes: number;
}

/**
 * Download a file from URL and save locally.
 * Returns null if download fails (non-fatal).
 */
export async function downloadAsset(
  url: string,
  destDir: string,
  filenamePrefix: string
): Promise<AssetDownloadResult | null> {
  try {
    await ensureDir(destDir);
    const ext = extname(new URL(url).pathname) || ".bin";
    const filename = `${sanitizeFilename(filenamePrefix)}${ext}`;
    const localPath = join(destDir, filename);

    const response = await fetch(url, {
      headers: {
        "User-Agent": "TIP-Scraper/1.0 (Transceiver Intelligence Platform)",
        "Accept": "*/*",
      },
      signal: AbortSignal.timeout(30_000),
    });

    if (!response.ok) {
      console.log(`    [SKIP] ${url} → HTTP ${response.status}`);
      return null;
    }

    const buffer = Buffer.from(await response.arrayBuffer());
    const hash = contentHash(buffer);

    await writeFile(localPath, buffer);

    return { localPath, hash, sizeBytes: buffer.length };
  } catch (err) {
    console.log(`    [FAIL] ${url} → ${(err as Error).message.slice(0, 80)}`);
    return null;
  }
}

/**
 * Download product image and update switches table.
 */
export async function downloadSwitchImage(
  switchId: string,
  imageUrl: string,
  vendor: string,
  model: string
): Promise<boolean> {
  const vendorDir = join(IMAGES_DIR, "switches", sanitizeFilename(vendor));
  const result = await downloadAsset(imageUrl, vendorDir, model);
  if (!result) return false;

  await pool.query(
    `UPDATE switches SET image_url = $2, image_local_path = $3, assets_scraped_at = NOW() WHERE id = $1`,
    [switchId, imageUrl, result.localPath]
  );
  return true;
}

/**
 * Download datasheet PDF and create product_documents entry.
 */
export async function downloadSwitchDatasheet(
  switchId: string,
  vendorId: string,
  datasheetUrl: string,
  title: string,
  vendor: string,
  model: string
): Promise<boolean> {
  const vendorDir = join(DATASHEETS_DIR, "switches", sanitizeFilename(vendor));
  const result = await downloadAsset(datasheetUrl, vendorDir, model);
  if (!result) return false;

  // Update switch record
  await pool.query(
    `UPDATE switches SET datasheet_url = $2, datasheet_local_path = $3, assets_scraped_at = NOW() WHERE id = $1`,
    [switchId, datasheetUrl, result.localPath]
  );

  // Create document record (upsert by content_hash)
  await pool.query(
    `INSERT INTO product_documents (switch_id, vendor_id, doc_type, title, source_url, local_path, file_size_bytes, content_hash)
     VALUES ($1, $2, 'datasheet', $3, $4, $5, $6, $7)
     ON CONFLICT (content_hash) DO UPDATE SET downloaded_at = NOW()`,
    [switchId, vendorId, title, datasheetUrl, result.localPath, result.sizeBytes, result.hash]
  );
  return true;
}

/**
 * Download manual/guide PDF and create product_documents entry.
 */
export async function downloadSwitchManual(
  switchId: string,
  vendorId: string,
  manualUrl: string,
  title: string,
  docType: string,
  vendor: string,
  model: string
): Promise<boolean> {
  const vendorDir = join(MANUALS_DIR, "switches", sanitizeFilename(vendor));
  const filename = `${sanitizeFilename(model)}-${sanitizeFilename(docType)}`;
  const result = await downloadAsset(manualUrl, vendorDir, filename);
  if (!result) return false;

  await pool.query(
    `INSERT INTO product_documents (switch_id, vendor_id, doc_type, title, source_url, local_path, file_size_bytes, content_hash)
     VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
     ON CONFLICT (content_hash) DO UPDATE SET downloaded_at = NOW()`,
    [switchId, vendorId, docType, title, manualUrl, result.localPath, result.sizeBytes, result.hash]
  );
  return true;
}

/**
 * Update switch product_page_url without downloading.
 */
export async function setSwitchProductPage(switchId: string, url: string): Promise<void> {
  await pool.query(
    `UPDATE switches SET product_page_url = $2, assets_scraped_at = NOW() WHERE id = $1`,
    [switchId, url]
  );
}

/**
 * Update vendor documentation portal URLs.
 */
export async function setVendorDocUrls(
  vendorId: string,
  urls: { docsPortal?: string; datasheetLibrary?: string; imageCdn?: string; supportPortal?: string }
): Promise<void> {
  await pool.query(
    `UPDATE vendors SET
      docs_portal_url = COALESCE($2, docs_portal_url),
      datasheet_library_url = COALESCE($3, datasheet_library_url),
      image_cdn_base = COALESCE($4, image_cdn_base),
      support_portal_url = COALESCE($5, support_portal_url),
      updated_at = NOW()
     WHERE id = $1`,
    [vendorId, urls.docsPortal || null, urls.datasheetLibrary || null, urls.imageCdn || null, urls.supportPortal || null]
  );
}