import os
import posixpath
import time


def _resolve_local_target(remote_path: str, target: str | None) -> str:
    if target:
        return target

    basename = posixpath.basename(remote_path.rstrip("/"))
    if not basename:
        raise ValueError("Kann keinen lokalen Dateinamen aus dem Remote-Pfad ableiten. Bitte Zielpfad angeben.")
    return basename


def execute(conn, source: str, target: str | None = None):
    local_path = _resolve_local_target(source, target)

    os.makedirs(os.path.dirname(local_path) or ".", exist_ok=True)

    last_print = 0.0
    start_time = time.monotonic()

    def _progress(_chunk_len: int, received: int, expected: int | None):
        nonlocal last_print
        now = time.monotonic()
        if now - last_print < 0.2:
            return
        last_print = now

        elapsed = max(now - start_time, 1e-6)
        speed_kb_s = (received / 1024.0) / elapsed

        if expected is not None and expected > 0:
            percent = (received * 100.0) / expected
            remaining = max(expected - received, 0)
            eta_sec = (remaining / 1024.0) / speed_kb_s if speed_kb_s > 0 else 0.0
            eta_str = f"{int(eta_sec // 60):02d}:{int(eta_sec % 60):02d}"
            print(
                f"\r⬇️  {received}/{expected} B ({percent:5.1f}%) | {speed_kb_s:6.1f} KB/s | ETA {eta_str}",
                end="",
                flush=True,
            )
        else:
            print(f"\r⬇️  {received} B | {speed_kb_s:6.1f} KB/s", end="", flush=True)

    data = conn.get_file_data(source, progress_callback=_progress)

    if len(data) > 0:
        print()

    with open(local_path, "wb") as f:
        f.write(data)

    total_duration = max(time.monotonic() - start_time, 1e-6)
    avg_speed_kb_s = (len(data) / 1024.0) / total_duration
    print(f"✅ Heruntergeladen: '{source}' -> '{local_path}' ({len(data)} B, {avg_speed_kb_s:.1f} KB/s)")
    return {
        "source": source,
        "target": local_path,
        "size": len(data),
    }