"""FFmpeg command builder for Deltacast SDI recording."""

import os
from datetime import datetime
from ..config import Settings
from ..models import RecorderConfig, CodecType


def _deltacast_device_exists(port_index: int) -> bool:
    return os.path.exists(f"/dev/deltacast{port_index}")


class FFmpegCommandBuilder:
    """Builds FFmpeg commands for Deltacast SDI recording."""

    def __init__(self, settings: Settings):
        self.settings = settings

    def build_command(self, config: RecorderConfig) -> list[str]:
        command = [self.settings.ffmpeg_path]
        command.extend(self._get_input_args(config.port_index))
        command.extend(self._get_codec_args(config))
        command.extend(self._get_output_args(config))

        # Multi-destination SRT outputs
        if config.srt_enabled:
            dests = [d for d in config.srt_destinations if d.enabled and d.url]
            if not dests and config.srt_destination:
                # Legacy single destination fallback
                dests_urls = [config.srt_destination]
            else:
                dests_urls = [d.url for d in dests]
            for url in dests_urls:
                command.extend(["-f", "mpegts", url])

        return command

    def _get_input_args(self, port_index: int) -> list[str]:
        if _deltacast_device_exists(port_index):
            return ["-f", "deltacast", "-i", f"deltacast://{port_index}"]
        else:
            # No physical device — use lavfi test source so recording still works for testing
            return [
                "-f", "lavfi",
                "-i", (
                    f"testsrc2=size=1920x1080:rate=30,"
                    f"drawtext=text='SDI PORT {port_index} — TEST MODE':"
                    f"fontsize=48:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2,"
                    f"drawtext=text='%{{localtime\\:%H\\:%M\\:%S}}':"
                    f"fontsize=32:fontcolor=yellow:x=10:y=10"
                ),
                "-f", "lavfi", "-i", "sine=frequency=1000:sample_rate=48000",
            ]

    def _get_codec_args(self, config: RecorderConfig) -> list[str]:
        args = []
        # Normalise bitrate — strip trailing M if present for numeric use
        bitrate = str(config.bitrate or "185M")
        bitrate_val = bitrate.rstrip("Mm")

        if config.codec == CodecType.PRORES:
            args.extend(["-c:v", "prores_ks"])
            profile_map = {"hq": "3", "mq": "2", "lq": "0"}
            args.extend(["-profile:v", profile_map.get(config.quality_profile, "3")])
            args.extend(["-c:a", "pcm_s16le"])
        elif config.codec == CodecType.DNXHD:
            args.extend(["-c:v", "dnxhd", "-b:v", f"{bitrate_val}M"])
            args.extend(["-c:a", "pcm_s16le"])
        elif config.codec == CodecType.UNCOMPRESSED:
            args.extend(["-c:v", "rawvideo", "-pix_fmt", "uyvy422"])
            args.extend(["-c:a", "pcm_s16le"])
        elif config.codec == CodecType.H264:
            args.extend(["-c:v", "libx264", "-preset", "fast", "-b:v", f"{bitrate_val}M"])
            args.extend(["-c:a", "aac", "-b:a", "192k"])
        return args

    def _get_output_args(self, config: RecorderConfig) -> list[str]:
        output_path = config.recording_path
        if "{timestamp}" in output_path:
            output_path = output_path.replace("{timestamp}", datetime.now().strftime("%Y%m%d_%H%M%S"))
        if "{port_index}" in output_path:
            output_path = output_path.replace("{port_index}", str(config.port_index))
        return [output_path]