import { createClient } from "https://esm.sh/@supabase/supabase-js@2";

const corsHeaders = {
  "Access-Control-Allow-Origin": "*",
  "Access-Control-Allow-Headers":
    "authorization, x-client-info, apikey, content-type, x-supabase-client-platform, x-supabase-client-platform-version, x-supabase-client-runtime, x-supabase-client-runtime-version",
};

const INITIAL_BATCH_SIZE = 1000;
const MIN_BATCH_SIZE = 100;
const MAX_BATCH_SIZE = 2000;
const BATCH_GROW_FACTOR = 1.25; // Increase by 25% on success
const BATCH_SHRINK_FACTOR = 0.5;  // Halve on error
const MAX_ROWS_PER_CALL = 50000;
const MAX_RETRIES = 3;
const RETRY_DELAY_MS = 2000;
const TIME_LIMIT_MS = 110000;
const LOG_INTERVAL = 5000;

// ─── GIN Index Definitions (to drop/recreate) ──────────────────────────────

const GIN_INDEXES = [
  { name: "idx_addr_formatee_trgm", def: `CREATE INDEX idx_addr_formatee_trgm ON public.addresses USING gin (adresse_formatee gin_trgm_ops)` },
  { name: "idx_addr_municipalite_trgm", def: `CREATE INDEX idx_addr_municipalite_trgm ON public.addresses USING gin (nom_municipalite gin_trgm_ops)` },
  { name: "idx_addr_odonyme_court_trgm", def: `CREATE INDEX idx_addr_odonyme_court_trgm ON public.addresses USING gin (odonyme_recompose_court gin_trgm_ops)` },
  { name: "idx_addr_odonyme_long_trgm", def: `CREATE INDEX idx_addr_odonyme_long_trgm ON public.addresses USING gin (odonyme_recompose_long gin_trgm_ops)` },
  { name: "idx_addr_odonyme_normal_trgm", def: `CREATE INDEX idx_addr_odonyme_normal_trgm ON public.addresses USING gin (odonyme_recompose_normal gin_trgm_ops)` },
  { name: "idx_addresses_adresse_formatee_trgm", def: `CREATE INDEX idx_addresses_adresse_formatee_trgm ON public.addresses USING gin (adresse_formatee gin_trgm_ops)` },
  { name: "idx_addresses_num_odonyme_trgm", def: `CREATE INDEX idx_addresses_num_odonyme_trgm ON public.addresses USING gin (((COALESCE(numero_municipal, ''::text) || ' '::text) || COALESCE(odonyme_recompose_normal, ''::text))) gin_trgm_ops)` },
];

// ─── CSV Parsing helpers ─────────────────────────────────────────────────────

function parseLine(line: string, delimiter: string): string[] {
  if (delimiter === "\t" || delimiter === ";") {
    return line.split(delimiter).map((v) => v.trim().replace(/^"|"$/g, ""));
  }
  const values: string[] = [];
  let current = "";
  let inQuotes = false;
  for (let i = 0; i < line.length; i++) {
    const char = line[i];
    if (char === '"') {
      if (inQuotes && i + 1 < line.length && line[i + 1] === '"') {
        current += '"';
        i++;
      } else {
        inQuotes = !inQuotes;
      }
    } else if (char === delimiter && !inQuotes) {
      values.push(current.trim());
      current = "";
    } else {
      current += char;
    }
  }
  values.push(current.trim());
  return values;
}

function normalizeHeader(name: string): string {
  return name
    .toLowerCase()
    .normalize("NFD")
    .replace(/[\u0300-\u036f]/g, "")
    .replace(/[_\s]+/g, "_")
    .replace(/[^a-z0-9_]/g, "")
    .trim();
}

const FIBER_HEADER_MAP: Record<string, string> = {
  id_placemark: "id_placemark", idplacemark: "id_placemark",
  id_appart: "id_appart", idappart: "id_appart",
  uuidadresse: "uuidadresse", idgouvqc: "uuidadresse", id_gouv_qc: "uuidadresse",
  nom: "nom", civique: "civique",
  appartement: "appartement", appt: "appartement", apt: "appartement",
  rue: "rue", ville: "ville",
  code_postal: "code_postal", codepostal: "code_postal", cp: "code_postal",
  lien_googlemap: "lien_googlemap", liengooglemap: "lien_googlemap", googlemap: "lien_googlemap",
  zone_tarifaire: "zone_tarifaire", zonetarifaire: "zone_tarifaire", zone: "zone_tarifaire",
  max_speed: "max_speed", maxspeed: "max_speed", vitesse: "max_speed", vitesse_max: "max_speed",
  commentaire: "commentaire", commentaires: "commentaire", comment: "commentaire",
  lien_map_targo: "_skip", lienmaptargo: "_skip",
};

// ─── Row Mapping ─────────────────────────────────────────────────────────────

function mapAddressRow(r: Record<string, string>) {
  return {
    identifiant_unique_adresse: r.identifiant_unique_adresse,
    date_diffusion_version: r.date_diffusion_version || null,
    date_creation: r.date_creation || null,
    date_modification: r.date_modification || null,
    date_fin: r.date_fin || null,
    numero_municipal: r.numero_municipal || null,
    numero_municipal_suffixe: r.numero_municipal_suffixe || null,
    numero_unite: r.numero_unite || null,
    type_unite: r.type_unite || null,
    code_postal: r.code_postal || null,
    seqodo: r.seqodo || null,
    generique_odonyme: r.generique_odonyme || null,
    particule_odonyme: r.particule_odonyme || null,
    specifique_odonyme: r.specifique_odonyme || null,
    point_cardinal_odonyme: r.point_cardinal_odonyme || null,
    odonyme_recompose_normal: r.odonyme_recompose_normal || null,
    odonyme_recompose_court: r.odonyme_recompose_court || null,
    odonyme_recompose_long: r.odonyme_recompose_long || null,
    discriminant_odonyme: r.discriminant_odonyme || null,
    odonyme_officiel_ctop: r.odonyme_officiel_ctop || null,
    adresse_formatee: r.adresse_formatee || null,
    qualite_positionnement_geometrique: r.qualite_positionnement_geometrique || null,
    etat: r.etat || null,
    code_utilisation: r.code_utilisation || null,
    categorie: r.categorie || null,
    nombre_unite: r.nombre_unite ? parseInt(r.nombre_unite) : null,
    numero_lot: r.numero_lot || null,
    matricule_unite_evaluation: r.matricule_unite_evaluation || null,
    nosqnocivq: r.nosqnocivq || null,
    caracteristique_adresse: r.caracteristique_adresse || null,
    code_region_administrative: r.code_region_administrative || null,
    nom_region_administrative: r.nom_region_administrative || null,
    code_mrc: r.code_mrc || null,
    nom_mrc: r.nom_mrc || null,
    code_municipalite: r.code_municipalite || null,
    nom_municipalite: r.nom_municipalite || null,
    nom_municipalite_complet: r.nom_municipalite_complet || null,
    code_arrondissement: r.code_arrondissement || null,
    nom_arrondissement: r.nom_arrondissement || null,
    code_communaute_metropolitaine: r.code_communaute_metropolitaine || null,
    nom_communaute_metropolitaine: r.nom_communaute_metropolitaine || null,
    identifiant_reseau_routier: r.identifiant_reseau_routier || null,
    cote_route: r.cote_route || null,
    longitude: r.longitude ? parseFloat(r.longitude) : null,
    latitude: r.latitude ? parseFloat(r.latitude) : null,
  };
}

function mapFiberRow(r: Record<string, string>) {
  if (!r.uuidadresse) return null;
  return {
    id_placemark: r.id_placemark || null,
    id_appart: r.id_appart || null,
    uuidadresse: r.uuidadresse,
    nom: r.nom || null,
    civique: r.civique || null,
    appartement: r.appartement || null,
    rue: r.rue || null,
    ville: r.ville || null,
    code_postal: r.code_postal || null,
    lien_googlemap: r.lien_googlemap || null,
    zone_tarifaire: r.zone_tarifaire ? parseInt(r.zone_tarifaire) : 1,
    max_speed: r.max_speed ? parseInt(r.max_speed) : 0,
    commentaire: r.commentaire || null,
  };
}

// ─── Upsert with retry ──────────────────────────────────────────────────────

async function insertWithRetry(
  supabase: any,
  table: string,
  batch: any[],
): Promise<{ error: any; timedOut: boolean }> {
  for (let attempt = 0; attempt < MAX_RETRIES; attempt++) {
    const { error } = await supabase.from(table).insert(batch);
    if (!error) return { error: null, timedOut: false };
    // On duplicate key, skip silently (data already exists)
    if (error.code === "23505") return { error: null, timedOut: false };
    const isTimeout = !!error.message?.includes("statement timeout");
    if (isTimeout && attempt < MAX_RETRIES - 1) {
      await new Promise((r) => setTimeout(r, RETRY_DELAY_MS * (attempt + 1)));
      continue;
    }
    return { error, timedOut: isTimeout };
  }
  return { error: { message: "Max retries exceeded" }, timedOut: true };
}

// ─── Index Management ───────────────────────────────────────────────────────

async function dropGinIndexes(supabase: any, log: (msg: string) => void) {
  log("🗑️ Dropping GIN trigram indexes for faster import…");
  for (const idx of GIN_INDEXES) {
    const { error } = await supabase.rpc("exec_sql", { query: `DROP INDEX IF EXISTS public.${idx.name}` });
    if (error) {
      // Try via direct SQL if rpc doesn't exist
      log(`⚠️ Could not drop ${idx.name} via rpc: ${error.message}`);
    } else {
      log(`  ✅ Dropped ${idx.name}`);
    }
  }
}

async function createGinIndexes(supabase: any, log: (msg: string) => void) {
  log("🔨 Recreating GIN trigram indexes (this may take a while)…");
  for (const idx of GIN_INDEXES) {
    const { error } = await supabase.rpc("exec_sql", { query: idx.def });
    if (error) {
      log(`⚠️ Could not create ${idx.name}: ${error.message}`);
    } else {
      log(`  ✅ Created ${idx.name}`);
    }
  }
}

// ─── Main Handler ────────────────────────────────────────────────────────────

Deno.serve(async (req) => {
  if (req.method === "OPTIONS") {
    return new Response(null, { headers: corsHeaders });
  }

  const serviceClient = createClient(
    Deno.env.get("SUPABASE_URL")!,
    Deno.env.get("SUPABASE_SERVICE_ROLE_KEY")!,
    { db: { schema: "public" }, global: { headers: { "x-statement-timeout": "120000" } } }
  );

  // Find the oldest active import job
  const { data: jobs, error: jobErr } = await serviceClient
    .from("import_jobs")
    .select("*")
    .in("status", ["running", "queued"])
    .order("created_at", { ascending: true })
    .limit(1);

  if (jobErr || !jobs || jobs.length === 0) {
    return new Response(JSON.stringify({ message: "No active jobs" }), {
      headers: { ...corsHeaders, "Content-Type": "application/json" },
    });
  }

  const job = jobs[0];
  const logLines: string[] = [...(job.logs || [])].slice(-300);

  function log(msg: string) {
    const ts = new Date().toISOString().slice(11, 19);
    logLines.push(`[${ts}] ${msg}`);
    console.log(`[process-import-job] ${msg}`);
  }

  const updateJob = async (updates: Record<string, any>) => {
    await serviceClient
      .from("import_jobs")
      .update({ ...updates, logs: logLines.slice(-500), updated_at: new Date().toISOString() })
      .eq("id", job.id);
  };

  await updateJob({ status: "running" });

  const url = job.source_url;
  if (!url) {
    log("❌ No source URL");
    await updateJob({ status: "error", error_messages: ["No source URL"] });
    return new Response(JSON.stringify({ error: "No source URL" }), {
      headers: { ...corsHeaders, "Content-Type": "application/json" },
    });
  }

  const type = job.type as "addresses" | "fiber";
  const byteOffset: number = job.byte_offset || 0;
  let totalInserted = job.total_inserted || 0;
  let totalErrors = job.total_errors || 0;
  const errorMessages: string[] = [...(job.error_messages || [])];
  const startTime = Date.now();

  // Detect if this is a direct CSV (not ZIP) — only CSV supports Range
  const isZip = url.toLowerCase().includes(".zip");
  const useRange = !isZip && byteOffset > 0;

  // Drop GIN indexes on addresses table for faster upserts (only on first chunk or when explicitly needed)
  const indexesDropped = job.indexes_dropped === true;
  if (type === "addresses" && !indexesDropped) {
    await dropGinIndexes(serviceClient, log);
    await updateJob({ indexes_dropped: true });
  }

  try {
    log(`🚀 Job ${job.id.slice(0, 8)}… type=${type} byteOffset=${byteOffset.toLocaleString()} totalInserted=${totalInserted.toLocaleString()}`);

    // Download the source file, using Range header for CSV resume
    const fetchHeaders: Record<string, string> = {};
    if (useRange) {
      fetchHeaders["Range"] = `bytes=${byteOffset}-`;
      log(`📥 Resuming from byte ${byteOffset.toLocaleString()}`);
    } else {
      log("📥 Downloading source file…");
    }

    const resp = await fetch(url, { headers: fetchHeaders });
    if (!resp.ok || !resp.body) {
      throw new Error(`Download failed: ${resp.status} ${resp.statusText}`);
    }

    const rangeSupported = useRange && resp.status === 206;
    if (useRange && !rangeSupported) {
      log(`⚠️ Server returned ${resp.status} instead of 206 — Range not supported, will skip rows`);
    }

    log(`📥 Download started (status ${resp.status})`);

    let csvStream: ReadableStream<Uint8Array>;

    if (isZip) {
      csvStream = await decompressZipStream(resp.body, log);
    } else {
      csvStream = resp.body;
    }

    // Process CSV from stream
    const streamReader = csvStream.getReader();
    const decoder = new TextDecoder("utf-8", { fatal: false });

    const knownHeaders = job.headers_cache as string[] | null;
    let headers: string[] = knownHeaders || [];
    let delimiter = ",";
    let leftover = "";
    let totalRowsRead = 0;
    let processedRows = 0;
    let inserted = 0;
    let errors = 0;
    let pendingRows: any[] = [];
    let done = false;
    let stoppedByLimit = false;
    let bytesConsumed = 0;
    let currentBatchSize = job.current_batch_size || INITIAL_BATCH_SIZE;
    let consecutiveSuccesses = 0;

    const needsHeaderDetection = headers.length === 0;
    if (!needsHeaderDetection) {
      log(`📋 Using cached headers (${headers.length} cols) | batch=${currentBatchSize}`);
    }

    const flushBatch = async (batch: any[]) => {
      if (batch.length === 0) return;
      const table = type === "addresses" ? "addresses" : "fiber_availability";
      const { error, timedOut } = await insertWithRetry(serviceClient, table, batch);
      if (error) {
        const msg = error.message || "Unknown error";
        if (timedOut) {
          // Shrink batch size on timeout — re-queue these rows by NOT counting them as errors
          const oldSize = currentBatchSize;
          currentBatchSize = Math.max(MIN_BATCH_SIZE, Math.floor(currentBatchSize * BATCH_SHRINK_FACTOR));
          consecutiveSuccesses = 0;
          log(`⚠️ Timeout on batch of ${batch.length} — shrinking batch ${oldSize} → ${currentBatchSize}`);
          // Split and retry the failed batch in smaller chunks
          for (let i = 0; i < batch.length; i += currentBatchSize) {
            const subBatch = batch.slice(i, i + currentBatchSize);
            const retry = await insertWithRetry(serviceClient, table, subBatch);
            if (retry.error) {
              errors += subBatch.length;
              if (errorMessages.length < 20) errorMessages.push(retry.error.message || msg);
            } else {
              inserted += subBatch.length;
            }
          }
        } else {
          log(`❌ Batch error (${batch.length} rows): ${msg}`);
          errors += batch.length;
          if (errorMessages.length < 20) errorMessages.push(msg);
        }
      } else {
        inserted += batch.length;
        consecutiveSuccesses++;
        // Grow batch size after 3 consecutive successes
        if (consecutiveSuccesses >= 3 && currentBatchSize < MAX_BATCH_SIZE) {
          const oldSize = currentBatchSize;
          currentBatchSize = Math.min(MAX_BATCH_SIZE, Math.floor(currentBatchSize * BATCH_GROW_FACTOR));
          if (currentBatchSize !== oldSize) {
            log(`🚀 3 successes — growing batch ${oldSize} → ${currentBatchSize}`);
          }
          consecutiveSuccesses = 0;
        }
      }
    };

    const skipRows = (!rangeSupported && !isZip) ? (job.skip_rows || 0) : 0;
    if (skipRows > 0) {
      log(`⏩ Will skip ${skipRows.toLocaleString()} rows (no Range support)`);
    }

    while (true) {
      if (Date.now() - startTime > TIME_LIMIT_MS) { stoppedByLimit = true; break; }
      if (processedRows >= MAX_ROWS_PER_CALL) { stoppedByLimit = true; break; }

      const { done: streamDone, value } = await streamReader.read();
      const chunk = value ? decoder.decode(value, { stream: !streamDone }) : "";
      if (value) bytesConsumed += value.byteLength;
      const text = leftover + chunk;
      const lines = text.split(/\r?\n/);
      leftover = streamDone ? "" : (lines.pop() || "");

      for (const line of lines) {
        const trimmed = line.trim();
        if (!trimmed) continue;

        if (headers.length === 0) {
          const cleanLine = trimmed.charCodeAt(0) === 0xfeff ? trimmed.slice(1) : trimmed;
          const tabCount = (cleanLine.match(/\t/g) || []).length;
          const semiCount = (cleanLine.match(/;/g) || []).length;
          const commaCount = (cleanLine.match(/,/g) || []).length;
          delimiter = tabCount >= semiCount && tabCount >= commaCount ? "\t"
            : semiCount >= commaCount ? ";" : ",";
          const candidateHeaders = parseLine(cleanLine, delimiter);
          if (candidateHeaders.length < 3) continue;
          headers = candidateHeaders;
          log(`📋 Headers (${headers.length}): ${headers.slice(0, 5).join(", ")}…`);
          continue;
        }

        // Auto-detect delimiter for Range resume
        if (needsHeaderDetection === false && totalRowsRead === 0 && processedRows === 0) {
          const tabCount = (trimmed.match(/\t/g) || []).length;
          const semiCount = (trimmed.match(/;/g) || []).length;
          const commaCount = (trimmed.match(/,/g) || []).length;
          delimiter = tabCount >= semiCount && tabCount >= commaCount ? "\t"
            : semiCount >= commaCount ? ";" : ",";
        }

        totalRowsRead++;

        if (skipRows > 0 && totalRowsRead <= skipRows) {
          if (totalRowsRead % 500000 === 0) {
            log(`⏩ Skipping… ${totalRowsRead.toLocaleString()} / ${skipRows.toLocaleString()}`);
          }
          continue;
        }

        const values = parseLine(trimmed, delimiter);
        const row: Record<string, string> = {};

        if (type === "fiber") {
          headers.forEach((h, idx) => {
            const norm = normalizeHeader(h);
            const dbCol = FIBER_HEADER_MAP[norm];
            if (dbCol && dbCol !== "_skip") {
              row[dbCol] = values[idx] || "";
            }
          });
        } else {
          headers.forEach((h, idx) => {
            row[h] = values[idx] || "";
          });
        }

        const mapped = type === "addresses" ? mapAddressRow(row) : mapFiberRow(row);
        if (mapped) {
          pendingRows.push(mapped);
          processedRows++;
        }

        if (pendingRows.length >= currentBatchSize) {
          await flushBatch(pendingRows);
          pendingRows = [];
        }

        // Log progress at regular intervals
        if (processedRows > 0 && processedRows % LOG_INTERVAL === 0) {
          const elapsed = ((Date.now() - startTime) / 1000).toFixed(0);
          const rate = (processedRows / ((Date.now() - startTime) / 1000)).toFixed(0);
          log(`📊 ${processedRows.toLocaleString()} rows (+${inserted.toLocaleString()} ok, ${errors} err) | ${rate} rows/s | batch=${currentBatchSize} | ${elapsed}s`);
          // Persist progress periodically
          await updateJob({
            total_inserted: totalInserted + inserted,
            total_errors: totalErrors + errors,
            byte_offset: byteOffset + bytesConsumed,
          });
        }

        if (processedRows >= MAX_ROWS_PER_CALL || Date.now() - startTime > TIME_LIMIT_MS) {
          stoppedByLimit = true;
          break;
        }
      }

      if (stoppedByLimit) break;
      if (streamDone) { done = true; break; }
    }

    // Flush remaining
    if (pendingRows.length > 0) {
      await flushBatch(pendingRows);
    }

    if (!done) {
      try { streamReader.cancel(); } catch {}
    }

    const newByteOffset = byteOffset + bytesConsumed;
    const nextSkipRows = (job.skip_rows || 0) + processedRows;
    totalInserted += inserted;
    totalErrors += errors;
    const isComplete = done && !stoppedByLimit;
    const elapsed = ((Date.now() - startTime) / 1000).toFixed(1);
    const rate = (processedRows / (parseFloat(elapsed) || 1)).toFixed(0);

    if (isComplete) {
      log(`✅ COMPLETE: ${processedRows.toLocaleString()} rows this run (${rate}/s), total: ${totalInserted.toLocaleString()}, errors: ${totalErrors} (${elapsed}s)`);
      
      // Recreate GIN indexes now that import is done
      if (type === "addresses") {
        await createGinIndexes(serviceClient, log);
      }
      
      await updateJob({
        status: "done",
        byte_offset: newByteOffset,
        skip_rows: nextSkipRows,
        total_inserted: totalInserted,
        total_errors: totalErrors,
        error_messages: errorMessages.slice(-20),
        indexes_dropped: false,
      });
    } else {
      log(`⏸️ Chunk: +${processedRows.toLocaleString()} rows (${rate}/s), inserted=${inserted.toLocaleString()}, batch=${currentBatchSize}, byteOffset=${newByteOffset.toLocaleString()} (${elapsed}s)`);
      await updateJob({
        status: "running",
        byte_offset: newByteOffset,
        skip_rows: nextSkipRows,
        total_inserted: totalInserted,
        total_errors: totalErrors,
        error_messages: errorMessages.slice(-20),
        headers_cache: headers,
        current_batch_size: currentBatchSize,
      });
    }

    return new Response(
      JSON.stringify({
        success: true,
        jobId: job.id,
        processed: processedRows,
        inserted,
        totalInserted,
        done: isComplete,
        byteOffset: newByteOffset,
      }),
      { headers: { ...corsHeaders, "Content-Type": "application/json" } }
    );
  } catch (err: any) {
    log(`💥 Fatal: ${err.message}`);
    console.error("[process-import-job] Error:", err);
    await updateJob({
      status: "paused",
      error_messages: [...errorMessages, err.message].slice(-20),
    });
    return new Response(JSON.stringify({ error: err.message }), {
      status: 500,
      headers: { ...corsHeaders, "Content-Type": "application/json" },
    });
  }
});

// ─── Streaming ZIP Decompression (legacy) ───────────────────────────────────

async function decompressZipStream(
  zipStream: ReadableStream<Uint8Array>,
  log: (msg: string) => void
): Promise<ReadableStream<Uint8Array>> {
  const reader = zipStream.getReader();
  let buffer = new Uint8Array(0);

  async function readBytes(n: number): Promise<Uint8Array> {
    while (buffer.length < n) {
      const { done, value } = await reader.read();
      if (done) throw new Error("Unexpected end of ZIP stream");
      const newBuf = new Uint8Array(buffer.length + value.length);
      newBuf.set(buffer);
      newBuf.set(value, buffer.length);
      buffer = newBuf;
    }
    const result = buffer.slice(0, n);
    buffer = buffer.slice(n);
    return result;
  }

  const header = await readBytes(30);
  const view = new DataView(header.buffer, header.byteOffset, header.byteLength);
  const sig = view.getUint32(0, true);
  if (sig !== 0x04034b50) {
    throw new Error(`Invalid ZIP local file header signature: 0x${sig.toString(16)}`);
  }

  const method = view.getUint16(8, true);
  const compressedSize = view.getUint32(18, true);
  const filenameLen = view.getUint16(26, true);
  const extraLen = view.getUint16(28, true);

  const nameExtra = await readBytes(filenameLen + extraLen);
  const filename = new TextDecoder().decode(nameExtra.slice(0, filenameLen));
  log(`📄 ZIP entry: "${filename}" method=${method === 8 ? "DEFLATE" : method === 0 ? "STORED" : method} size=${compressedSize > 0 ? (compressedSize / 1024 / 1024).toFixed(1) + "MB" : "streaming"}`);

  const remainingStream = new ReadableStream<Uint8Array>({
    async pull(controller) {
      if (buffer.length > 0) {
        controller.enqueue(buffer);
        buffer = new Uint8Array(0);
        return;
      }
      const { done, value } = await reader.read();
      if (done) { controller.close(); return; }
      controller.enqueue(value);
    },
    cancel() { reader.cancel(); },
  });

  if (method === 0) {
    return remainingStream;
  } else if (method === 8) {
    log("🔓 Streaming DEFLATE decompression...");
    return remainingStream.pipeThrough(new DecompressionStream("deflate-raw"));
  } else {
    throw new Error(`Unsupported ZIP compression method: ${method}`);
  }
}