"""Gradio web interface for StemSplitter."""

from __future__ import annotations

import logging
from pathlib import Path

import gradio as gr

from stemsplitter.config import get_settings
from stemsplitter.separator import OutputFormat, StemMode, StemSplitter

logger = logging.getLogger(__name__)

_splitter: StemSplitter | None = None


def _get_splitter() -> StemSplitter:
    """Get or create the module-level StemSplitter singleton."""
    global _splitter
    if _splitter is None:
        settings = get_settings()
        Path(settings.output_dir).mkdir(parents=True, exist_ok=True)
        _splitter = StemSplitter(settings=settings)
    return _splitter


def separate_audio(
    audio_path: str,
    mode: str,
    output_format: str,
    progress: gr.Progress = gr.Progress(),
) -> list[str | None]:
    """Gradio handler: separate audio and return stem file paths.

    Returns a list of 4 file paths (padding with None for 2-stem mode).
    """
    if not audio_path:
        raise gr.Error("Please upload an audio file.")

    progress(0.1, desc="Initializing model...")
    splitter = _get_splitter()

    stem_mode = StemMode(mode)
    fmt = OutputFormat(output_format)

    progress(0.3, desc=f"Separating stems ({stem_mode.value})...")
    result = splitter.separate(
        input_path=audio_path,
        mode=stem_mode,
        output_format=fmt,
    )

    progress(1.0, desc="Done!")

    outputs = list(result.output_files)
    while len(outputs) < 4:
        outputs.append(None)

    return outputs[:4]


def create_app() -> gr.Blocks:
    """Build and return the Gradio Blocks application."""
    with gr.Blocks(title="StemSplitter") as app:
        gr.Markdown("# StemSplitter\nSeparate audio into individual stems.")

        with gr.Row():
            with gr.Column(scale=1):
                audio_input = gr.Audio(
                    label="Upload Audio",
                    type="filepath",
                    sources=["upload"],
                )
                mode_radio = gr.Radio(
                    choices=["2stem", "4stem"],
                    value="2stem",
                    label="Separation Mode",
                    info="2-stem: Vocals + Instrumental | 4-stem: Vocals + Drums + Bass + Other",
                )
                format_radio = gr.Radio(
                    choices=["WAV", "MP3", "FLAC"],
                    value="WAV",
                    label="Output Format",
                )
                separate_btn = gr.Button("Separate", variant="primary")

            with gr.Column(scale=2):
                vocals_output = gr.Audio(label="Vocals", type="filepath")
                instrumental_output = gr.Audio(
                    label="Instrumental", type="filepath"
                )
                drums_output = gr.Audio(
                    label="Drums",
                    type="filepath",
                    visible=False,
                )
                bass_output = gr.Audio(
                    label="Bass",
                    type="filepath",
                    visible=False,
                )

        def update_outputs_visibility(mode: str):
            is_4stem = mode == "4stem"
            return (
                gr.update(label="Instrumental" if not is_4stem else "Other"),
                gr.update(visible=is_4stem),
                gr.update(visible=is_4stem),
            )

        mode_radio.change(
            fn=update_outputs_visibility,
            inputs=[mode_radio],
            outputs=[instrumental_output, drums_output, bass_output],
        )

        separate_btn.click(
            fn=separate_audio,
            inputs=[audio_input, mode_radio, format_radio],
            outputs=[
                vocals_output,
                instrumental_output,
                drums_output,
                bass_output,
            ],
        )

    return app


def launch() -> None:
    """Entry point for `stemsplitter-web` console script."""
    settings = get_settings()
    app = create_app()
    app.launch(
        server_name=settings.web_host,
        server_port=settings.web_port,
        theme=gr.themes.Soft(),
        share=True,
    )