"""Read FFmpeg's real timeline and output size without blocking stderr."""
from __future__ import annotations

import math
import subprocess
import threading
from host.media import NO_WINDOW


def run_ffmpeg(command, duration, stage, engine, report):
    duration = float(duration or 0)
    if not math.isfinite(duration) or duration < 0:
        duration = 0
    report(stage=stage, percent=0 if duration else None, engine=engine,
           speed="", eta=None, processedSeconds=0, durationSeconds=duration, written=0, message="")
    process = subprocess.Popen(command, stdin=subprocess.DEVNULL, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                               text=True, encoding="utf-8", errors="replace", creationflags=NO_WINDOW)
    errors, finalizing = [], threading.Event()
    progress_lock = threading.Lock()

    def read_errors():
        for line in process.stderr:
            errors.append(line)
            if len(errors) > 80:
                del errors[:40]
            if "Starting second pass" in line:
                with progress_lock:
                    finalizing.set()
                    report(stage="finalizing", percent=99, engine="copy", speed="", eta=None,
                           message="Финализация файла")

    reader = threading.Thread(target=read_errors, daemon=True)
    reader.start()
    stats = {}
    elapsed = 0.0
    try:
        for raw in process.stdout:
            key, _, value = raw.strip().partition("=")
            stats[key] = value
            if key != "progress":
                continue
            try:
                elapsed = max(elapsed, max(0, int(stats.get("out_time_us", "0")) / 1_000_000))
            except ValueError:
                pass
            speed = stats.get("speed", "")
            try:
                rate = float(speed.rstrip("x"))
            except ValueError:
                rate = 0
            eta = max(0, (duration - elapsed) / rate) if duration and rate > 0 and math.isfinite(rate) and not finalizing.is_set() else None
            try:
                written = max(0, int(stats.get("total_size", "0")))
            except ValueError:
                written = None
            with progress_lock:
                is_finalizing = finalizing.is_set()
                report(stage="finalizing" if is_finalizing else stage, percent=99 if is_finalizing else min(99, elapsed / duration * 100) if duration else None,
                       engine="copy" if is_finalizing else engine, speed=speed if rate > 0 and math.isfinite(rate) and not is_finalizing else "", eta=None if is_finalizing else eta,
                       processedSeconds=min(elapsed, duration) if duration else elapsed,
                       durationSeconds=duration, written=written,
                       message="Финализация файла" if is_finalizing else "")
        process.wait()
        reader.join(timeout=3)
        return process.returncode, "".join(errors)[-2000:]
    finally:
        if process.poll() is None:
            process.kill()
            process.wait(timeout=10)
        for stream in (process.stdout, process.stderr):
            stream.close()