web_interface/app.py

"""
Oppai ONNX tagger — single-file launcher.

First run: creates `.venv/`, installs requirements, re-execs inside the venv,
then starts a local Gradio web UI on http://127.0.0.1:7860 .

If the user has no Python at all, `run.bat` instead drops a portable Python
into `.pyenv/` and uses that. In that case `app.py` skips venv creation and
installs requirements directly into the portable Python's site-packages.

Subsequent runs: skip install (marker file) and start the UI immediately.

For most users:
    Just run `run.bat` (or `py app.py`). The launcher will show a numbered
    menu so you can pick an existing model or download one — no flags
    required. Press Enter to accept the highlighted default at any prompt.

Advanced flags:
    py app.py --reinstall              # force re-install of requirements
    py app.py --model-dir <folder>     # skip the menu, load a specific folder

Models live in folders next to this script. Any folder containing
`model.onnx`, `selected_tags.csv`, and `preprocessing.json` is treated as a
model and will appear in the launcher menu and the UI's model picker. You
can also download variants from https://huggingface.co/Grio43/OppaiOracle
directly from the menu or from the UI.
"""

from __future__ import annotations

import os
import subprocess
import sys
import venv
from pathlib import Path

ROOT = Path(__file__).resolve().parent
VENV_DIR = ROOT / ".venv"
MARKER = VENV_DIR / ".bootstrapped"

# Portable Python lives here when run.bat had to download one because no
# system Python was available. When app.py is launched by .pyenv/python.exe,
# we install requirements directly into that interpreter — no venv needed.
PYENV_DIR = ROOT / ".pyenv"
PYENV_MARKER = PYENV_DIR / ".bootstrapped"

# Microsoft Visual C++ 2015-2022 redistributable (x64). onnxruntime's native
# DLLs depend on this; if it's missing the import fails with
# "DLL load failed while importing onnxruntime_pybind11_state".
VC_REDIST_URL = "https://aka.ms/vs/17/release/vc_redist.x64.exe"

# Default folder if it exists; otherwise the first auto-discovered folder
# next to this script is used. Override with --model-dir or the UI picker.
DEFAULT_MODEL_DIR = ROOT / "V1.1_onnx"

# Variants published on HuggingFace that are usable with this ONNX runtime.
# First entry is the recommended default in interactive prompts.
HF_REPO_ID = "Grio43/OppaiOracle"
HF_VARIANTS = ["V1.1_onnx", "V1_onnx"]
HF_VARIANT_DESC = {
    "V1.1_onnx": "448×448, higher accuracy",
    "V1_onnx":   "320×320, smaller and faster",
}

REQUIREMENTS = [
    "onnxruntime>=1.20",
    "pillow>=10.0",
    "numpy>=1.26,<3",
    "gradio>=4.44",
    "huggingface_hub>=0.24",
]


# ---------------------------------------------------------------------------
# Bootstrap
# ---------------------------------------------------------------------------

def _venv_python() -> Path:
    if os.name == "nt":
        return VENV_DIR / "Scripts" / "python.exe"
    return VENV_DIR / "bin" / "python"


def _in_target_venv() -> bool:
    # Belt-and-suspenders: compare both sys.executable and sys.prefix against
    # the target venv. Windows Store Python uses reparse points that can make
    # Path.resolve() on sys.executable return a path that differs from the
    # venv's python.exe even when running inside it; sys.prefix is more
    # reliable for that case. Either match counts as "in venv".
    try:
        target_py = _venv_python().resolve()
    except OSError:
        target_py = None
    try:
        target_dir = VENV_DIR.resolve()
    except OSError:
        target_dir = None
    try:
        if target_py is not None and Path(sys.executable).resolve() == target_py:
            return True
    except OSError:
        pass
    try:
        if target_dir is not None and Path(sys.prefix).resolve() == target_dir:
            return True
    except OSError:
        pass
    return False


def _bootstrap(force_reinstall: bool) -> None:
    if not VENV_DIR.exists():
        print(f"[bootstrap] Creating virtualenv at {VENV_DIR} ...")
        venv.EnvBuilder(with_pip=True, clear=False, upgrade_deps=False).create(VENV_DIR)

    py = _venv_python()
    needs_install = force_reinstall or not MARKER.exists()
    if needs_install:
        print("[bootstrap] Upgrading pip ...")
        subprocess.check_call([str(py), "-m", "pip", "install", "--upgrade", "pip"])
        print(f"[bootstrap] Installing: {', '.join(REQUIREMENTS)}")
        subprocess.check_call([str(py), "-m", "pip", "install", *REQUIREMENTS])
        MARKER.write_text("ok\n", encoding="utf-8")
    else:
        print("[bootstrap] Requirements already installed (delete .venv/.bootstrapped to redo).")

    args = [a for a in sys.argv[1:] if a != "--reinstall"]
    print("[bootstrap] Re-launching inside venv ...\n")
    sys.exit(subprocess.call([str(py), str(Path(__file__).resolve()), *args]))


# ---------------------------------------------------------------------------
# Portable-Python bootstrap (run.bat path when no system Python exists)
# ---------------------------------------------------------------------------

def _running_portable_python() -> bool:
    """True when sys.executable lives inside ROOT/.pyenv/."""
    try:
        return Path(sys.executable).resolve().parent == PYENV_DIR.resolve()
    except OSError:
        return False


def _bootstrap_portable(force_reinstall: bool) -> None:
    """Install pip + requirements directly into the embedded Python.

    Embeddable Python ships without pip and disables `import site` by default,
    so we fix both before pip-installing the rest. No re-exec is needed —
    we're already running inside the target interpreter.
    """
    py = Path(sys.executable)

    # 1) Enable site-packages by uncommenting `import site` in pythonXY._pth.
    pth_files = sorted(py.parent.glob("python*._pth"))
    for pth in pth_files:
        try:
            text = pth.read_text(encoding="utf-8")
        except OSError:
            continue
        new_text = text
        for needle in ("#import site", "# import site"):
            if needle in new_text:
                new_text = new_text.replace(needle, "import site")
        if new_text != text:
            try:
                pth.write_text(new_text, encoding="utf-8")
                print(f"[bootstrap] Enabled site-packages in {pth.name}.")
            except OSError as e:
                print(f"[bootstrap] Could not edit {pth}: {e}")

    # 2) Install pip if missing.
    has_pip = subprocess.call(
        [str(py), "-m", "pip", "--version"],
        stdout=subprocess.DEVNULL,
        stderr=subprocess.DEVNULL,
    ) == 0
    if not has_pip:
        print("[bootstrap] Installing pip into portable Python ...")
        import urllib.request
        getpip = py.parent / "_get-pip.py"
        try:
            urllib.request.urlretrieve("https://bootstrap.pypa.io/get-pip.py", getpip)
            subprocess.check_call([str(py), str(getpip), "--no-warn-script-location"])
        finally:
            try:
                getpip.unlink()
            except OSError:
                pass

    # 3) Install requirements (skipped if marker says we already did it).
    needs_install = force_reinstall or not PYENV_MARKER.exists()
    if needs_install:
        print("[bootstrap] Upgrading pip ...")
        subprocess.check_call([str(py), "-m", "pip", "install", "--upgrade", "pip"])
        print(f"[bootstrap] Installing: {', '.join(REQUIREMENTS)}")
        subprocess.check_call([str(py), "-m", "pip", "install", *REQUIREMENTS])
        PYENV_MARKER.write_text("ok\n", encoding="utf-8")
    else:
        print("[bootstrap] Requirements already installed (delete .pyenv/.bootstrapped to redo).")


# ---------------------------------------------------------------------------
# onnxruntime / Visual C++ runtime recovery
# ---------------------------------------------------------------------------

def _looks_like_vcredist_failure(err: BaseException) -> bool:
    """Heuristic: did onnxruntime fail to load because VC++ runtime DLLs
    aren't on the box? The exact wording varies slightly by Windows version
    but always mentions the failed DLL by name."""
    if os.name != "nt":
        return False
    msg = str(err)
    return "DLL load failed" in msg and "onnxruntime_pybind11_state" in msg


def _install_vcredist_with_uac() -> bool:
    """Download vc_redist.x64.exe and run it elevated. Returns True on
    apparent success (exit 0 or 3010 = success-pending-reboot)."""
    if os.name != "nt":
        return False
    import urllib.request
    dest = ROOT / ".vc_redist.x64.exe"
    print(f"[runtime] Downloading {VC_REDIST_URL} ...")
    try:
        urllib.request.urlretrieve(VC_REDIST_URL, dest)
    except Exception as e:  # noqa: BLE001
        print(f"[runtime] Download failed: {e}")
        return False

    # Start-Process -Verb RunAs is what triggers the UAC prompt; -Wait blocks
    # until the installer exits so we can read its exit code. Apostrophes in
    # the path are escaped by doubling for PowerShell's single-quote syntax.
    ps_dest = str(dest).replace("'", "''")
    ps_cmd = (
        "$ErrorActionPreference='Stop';"
        f"$p = Start-Process -FilePath '{ps_dest}' "
        "-ArgumentList '/install','/quiet','/norestart' "
        "-Verb RunAs -Wait -PassThru;"
        "exit $p.ExitCode"
    )
    print("[runtime] Launching installer — accept the UAC prompt to continue.")
    try:
        rc = subprocess.call(
            ["powershell", "-NoProfile", "-ExecutionPolicy", "Bypass", "-Command", ps_cmd]
        )
    except OSError as e:
        print(f"[runtime] Could not launch installer: {e}")
        rc = -1
    finally:
        try:
            dest.unlink()
        except OSError:
            pass

    if rc in (0, 3010):
        if rc == 3010:
            print("[runtime] Install succeeded but Windows requested a reboot.")
        return True
    if rc == 1602 or rc == 1223:
        print("[runtime] Install was cancelled at the UAC prompt.")
    else:
        print(f"[runtime] Installer exited with code {rc}.")
    return False


def _recover_and_relaunch_after_vcredist() -> None:
    """Try to install the VC++ redistributable, then re-exec the launcher so
    the onnxruntime DLL gets a fresh load attempt. Windows caches failed DLL
    loads within a process, so re-importing in-place doesn't work."""
    print()
    print("=" * 60)
    print("  onnxruntime failed to load")
    print("=" * 60)
    print("This almost always means the Microsoft Visual C++ 2015-2022")
    print("Redistributable (x64) is missing on this Windows machine.")
    print("Trying to install it for you now — you'll see a UAC prompt.")
    print()

    if not _install_vcredist_with_uac():
        print()
        print("Manual fix:")
        print(f"  1. Download {VC_REDIST_URL}")
        print("  2. Run it (accept the UAC prompt)")
        print("  3. Re-run this script")
        print()
        print("If install keeps failing, your CPU may lack AVX2 support, which")
        print("modern onnxruntime wheels require. Most CPUs from 2014+ have it.")
        sys.exit(1)

    args = [a for a in sys.argv[1:] if a != "--reinstall"]
    print("\n[runtime] Visual C++ runtime installed. Re-launching the app ...\n")
    rc = subprocess.call([sys.executable, str(Path(__file__).resolve()), *args])
    sys.exit(rc)


# ---------------------------------------------------------------------------
# App
# ---------------------------------------------------------------------------

REQUIRED_FILES = ("model.onnx", "selected_tags.csv", "preprocessing.json")


def _discover_model_dirs() -> list[Path]:
    """Return every subdirectory of ROOT that looks like a usable model folder."""
    out: list[Path] = []
    if not ROOT.exists():
        return out
    for sub in sorted(ROOT.iterdir(), key=lambda p: p.name.lower()):
        if not sub.is_dir():
            continue
        if all((sub / f).exists() for f in REQUIRED_FILES):
            out.append(sub)
    return out


def _variant_rank(name: str) -> int:
    try:
        return HF_VARIANTS.index(name)
    except ValueError:
        return len(HF_VARIANTS)


def _is_tty() -> bool:
    try:
        return sys.stdin.isatty() and sys.stdout.isatty()
    except (AttributeError, OSError):
        return False


def _prompt_choice(prompt: str, options: list[tuple[str, str]], default_idx: int = 0) -> str | None:
    """Show a numbered terminal menu. Returns the chosen option's value, or None on EOF.

    options: list of (display_text, value).
    """
    if not options:
        return None
    if not _is_tty():
        return options[default_idx][1]

    print()
    print(prompt)
    for i, (display, _) in enumerate(options, 1):
        marker = "  <- press Enter for this" if i - 1 == default_idx else ""
        print(f"  {i}) {display}{marker}")
    while True:
        try:
            raw = input(f"Choice [1-{len(options)}, default {default_idx + 1}]: ").strip()
        except EOFError:
            return options[default_idx][1]
        if not raw:
            return options[default_idx][1]
        try:
            idx = int(raw) - 1
        except ValueError:
            print(f"  Please enter a number 1-{len(options)}.")
            continue
        if 0 <= idx < len(options):
            return options[idx][1]
        print(f"  Out of range. Pick 1-{len(options)}.")


def _download_variant(variant: str) -> Path | None:
    """Download a HuggingFace variant into ROOT/<variant>. Returns the folder on success."""
    try:
        from huggingface_hub import snapshot_download
    except ImportError:
        print("[app] huggingface_hub is not installed — re-run with --reinstall.")
        return None

    print(f"[app] Downloading '{variant}' from huggingface.co/{HF_REPO_ID} ...")
    try:
        snapshot_download(
            repo_id=HF_REPO_ID,
            allow_patterns=[f"{variant}/*"],
            local_dir=str(ROOT),
        )
    except Exception as e:  # noqa: BLE001
        print(f"[app] Download failed: {e}")
        return None

    target = ROOT / variant
    missing = [f for f in REQUIRED_FILES if not (target / f).exists()]
    if missing:
        print(f"[app] Download finished but {target} is missing: {', '.join(missing)}")
        return None
    return target


def _interactive_pick_model() -> Path | None:
    """Show a friendly menu so non-technical users can pick or download a model.

    Returns the chosen model directory, or None if the user wants to start the
    UI without loading anything (they can pick from the web UI then).
    """
    discovered = _discover_model_dirs()
    discovered.sort(key=lambda p: (_variant_rank(p.name), p.name.lower()))
    discovered_names = {p.name for p in discovered}

    options: list[tuple[str, str]] = []
    actions: list[tuple[str, str]] = []  # parallel list of (action, payload)

    for p in discovered:
        desc = HF_VARIANT_DESC.get(p.name, "model folder")
        options.append((f"Use {p.name}  ({desc})", str(p)))
        actions.append(("load", str(p)))

    for v in HF_VARIANTS:
        if v in discovered_names:
            continue
        desc = HF_VARIANT_DESC.get(v, "")
        suffix = f"  ({desc})" if desc else ""
        options.append((f"Download {v} from HuggingFace{suffix}", v))
        actions.append(("download", v))

    options.append(("Open the web UI without loading anything (pick later from the page)", "skip"))
    actions.append(("skip", ""))

    if not _is_tty() and discovered:
        return discovered[0]
    if not _is_tty():
        return None

    print()
    print("=" * 50)
    print("  Oppai ONNX Tagger")
    print("=" * 50)
    if discovered:
        print(f"Found {len(discovered)} model folder(s) next to app.py.")
    else:
        print("No model folders found yet next to app.py.")
        print(f"Pick a variant to download from huggingface.co/{HF_REPO_ID}.")

    chosen = _prompt_choice("What would you like to do?", options, default_idx=0)
    if chosen is None:
        return None

    idx = next(i for i, (_, v) in enumerate(options) if v == chosen)
    action, payload = actions[idx]
    if action == "load":
        return Path(payload)
    if action == "download":
        return _download_variant(payload)
    return None  # skip


def _resolve_initial_model(cli_dir: str | None) -> Path | None:
    if cli_dir:
        p = Path(cli_dir).expanduser().resolve()
        if not p.is_dir():
            print(f"[app] --model-dir not a directory: {p}")
            return None
        missing = [f for f in REQUIRED_FILES if not (p / f).exists()]
        if missing:
            print(f"[app] --model-dir is missing required files: {', '.join(missing)}")
            return None
        return p
    return _interactive_pick_model()


def _run_app() -> None:
    import argparse
    import csv
    import json

    import numpy as np
    try:
        import onnxruntime as ort
    except ImportError as e:
        if _looks_like_vcredist_failure(e):
            _recover_and_relaunch_after_vcredist()
            sys.exit(1)  # only reached if recover failed without exiting
        raise
    import gradio as gr
    from PIL import Image

    parser = argparse.ArgumentParser(add_help=False)
    parser.add_argument("--model-dir", type=str, default=None)
    cli_args, _ = parser.parse_known_args()

    cat_names = {0: "general", 1: "artist", 3: "copyright", 4: "character", 5: "meta"}
    inv_cat_names = {v: k for k, v in cat_names.items()}

    # Mutable holder so the UI can swap models without restarting the process.
    state: dict = {
        "session": None,
        "tag_names": [],
        "categories": [],
        "skip_mask": None,
        "image_size": 0,
        "pad_color": (0, 0, 0),
        "mean": None,
        "std": None,
        "breakeven_threshold": None,
        "model_dir": None,
        "providers": [],
    }

    def _ort_providers() -> list[str]:
        available = ort.get_available_providers()
        if "DmlExecutionProvider" in available:
            return ["DmlExecutionProvider", "CPUExecutionProvider"]
        if "CUDAExecutionProvider" in available:
            return ["CUDAExecutionProvider", "CPUExecutionProvider"]
        return ["CPUExecutionProvider"]

    def load_model(model_dir: Path) -> str:
        model_dir = Path(model_dir).expanduser().resolve()
        if not model_dir.is_dir():
            raise FileNotFoundError(f"not a directory: {model_dir}")
        missing = [f for f in REQUIRED_FILES if not (model_dir / f).exists()]
        if missing:
            raise FileNotFoundError(
                f"{model_dir} is missing required files: {', '.join(missing)}"
            )

        tag_names: list[str] = []
        categories: list[int] = []
        with (model_dir / "selected_tags.csv").open(encoding="utf-8") as f:
            for row in csv.DictReader(f):
                tag_names.append(row["name"])
                categories.append(int(row["category"]))
        n_tags = len(tag_names)

        skip_mask = np.zeros(n_tags, dtype=bool)
        for i, name in enumerate(tag_names):
            if name in ("<PAD>", "<UNK>"):
                skip_mask[i] = True

        with (model_dir / "preprocessing.json").open(encoding="utf-8") as f:
            preproc = json.load(f)
        image_size = int(preproc["image_size"])
        pad_color = tuple(int(c) for c in preproc["pad_color_rgb"])
        mean = np.array(preproc["normalize_mean"], dtype=np.float32).reshape(3, 1, 1)
        std = np.array(preproc["normalize_std"], dtype=np.float32).reshape(3, 1, 1)

        # Calibrated breakeven (precision = recall) lives in pr_thresholds.json.
        # It is tuned for whole-eval-set precision and is far too strict for
        # interactive single-image tagging, so we surface it only as a hint.
        breakeven_threshold = None
        thr_path = model_dir / "pr_thresholds.json"
        if thr_path.exists():
            try:
                with thr_path.open(encoding="utf-8") as f:
                    thr_data = json.load(f)
                breakeven_threshold = float(thr_data["micro"]["pr_breakeven"]["threshold"])
            except (OSError, KeyError, ValueError, json.JSONDecodeError):
                pass

        providers = _ort_providers()
        sess_opts = ort.SessionOptions()
        sess_opts.graph_optimization_level = ort.GraphOptimizationLevel.ORT_ENABLE_ALL
        print(f"[app] Loading {model_dir / 'model.onnx'} ({image_size}×{image_size}) ...")
        print(f"[app] Providers: {providers}")
        session = ort.InferenceSession(
            str(model_dir / "model.onnx"), sess_options=sess_opts, providers=providers
        )

        state.update(
            session=session,
            tag_names=tag_names,
            categories=categories,
            skip_mask=skip_mask,
            image_size=image_size,
            pad_color=pad_color,
            mean=mean,
            std=std,
            breakeven_threshold=breakeven_threshold,
            model_dir=model_dir,
            providers=providers,
        )
        return _status_md()

    def _status_md() -> str:
        if state["session"] is None:
            return (
                "**No model loaded.** Drop an ONNX model folder next to "
                "`app.py`, or use the **Download from HuggingFace** section below."
            )
        try:
            display = state["model_dir"].relative_to(ROOT)
        except ValueError:
            display = state["model_dir"]
        parts = [
            f"**Loaded:** `{display}`",
            f"{state['image_size']}×{state['image_size']}",
            f"{len(state['tag_names'])} tags",
            f"providers: {', '.join(state['providers'])}",
        ]
        if state["breakeven_threshold"] is not None:
            parts.append(f"P=R breakeven: {state['breakeven_threshold']:.3f}")
        return " — ".join(parts)

    def _dropdown_choices() -> list[tuple[str, str]]:
        out = []
        for p in _discover_model_dirs():
            try:
                label = str(p.relative_to(ROOT))
            except ValueError:
                label = p.name
            out.append((label, str(p)))
        return out

    def _current_value() -> str | None:
        return str(state["model_dir"]) if state["model_dir"] else None

    # Initial load (CLI override > default folder > first discovered)
    initial = _resolve_initial_model(cli_args.model_dir)
    if initial is not None:
        try:
            load_model(initial)
        except Exception as e:  # noqa: BLE001
            print(f"[app] Initial model load failed: {e!r}")
    else:
        print("[app] No model folder found yet — pick or download one in the UI.")

    def letterbox(img: Image.Image):
        img = img.convert("RGB")
        w, h = img.size
        size = state["image_size"]
        scale = min(size / w, size / h)
        nw, nh = max(1, int(round(w * scale))), max(1, int(round(h * scale)))
        resized = img.resize((nw, nh), Image.BICUBIC)
        canvas = Image.new("RGB", (size, size), state["pad_color"])
        x0 = (size - nw) // 2
        y0 = (size - nh) // 2
        canvas.paste(resized, (x0, y0))
        mask = np.ones((size, size), dtype=bool)  # True = padded
        mask[y0:y0 + nh, x0:x0 + nw] = False
        return canvas, mask

    def preprocess(img: Image.Image):
        canvas, mask = letterbox(img)
        arr = np.asarray(canvas, dtype=np.float32) / 255.0
        arr = arr.transpose(2, 0, 1)  # CHW
        arr = (arr - state["mean"]) / state["std"]
        return arr.astype(np.float32), mask

    def predict(image, threshold: float, max_tags, category_filter):
        if state["session"] is None:
            return "", "*no model loaded — pick or download one above*"
        if image is None:
            return "", "*upload an image to start*"
        try:
            max_tags_i = int(max_tags) if max_tags is not None else 0
            if max_tags_i <= 0:
                return "", "*no tags above threshold*"

            # An empty list means "no categories selected" -> show nothing.
            # `None` (event before component initialized) means "no filter".
            if category_filter is None:
                keep_cats = None
            else:
                keep_cats = {inv_cat_names[c] for c in category_filter if c in inv_cat_names}
                if not keep_cats:
                    return "", "*no tags above threshold*"

            pixel_values, padding_mask = preprocess(image)
            outputs = state["session"].run(
                ["probabilities"],
                {
                    "pixel_values": pixel_values[None, ...],
                    "padding_mask": padding_mask[None, ...],
                },
            )
            probs = outputs[0][0].astype(np.float32)
            probs[state["skip_mask"]] = -1.0  # never surface PAD/UNK

            order = np.argsort(-probs)
            results = []
            tag_names = state["tag_names"]
            categories = state["categories"]
            for idx in order:
                p = float(probs[idx])
                if p < threshold:
                    break
                cat = categories[idx]
                if keep_cats is not None and cat not in keep_cats:
                    continue
                results.append((tag_names[idx], p, cat))
                if len(results) >= max_tags_i:
                    break

            if not results:
                return "", "*no tags above threshold*"

            comma = ", ".join(name.replace("_", " ") for name, _, _ in results)
            lines = ["| # | Tag | Confidence | Category |", "|---|---|---|---|"]
            for i, (name, p, cat) in enumerate(results, 1):
                lines.append(f"| {i} | `{name}` | {p:.3f} | {cat_names.get(cat, str(cat))} |")
            return comma, "\n".join(lines)
        except Exception as e:  # noqa: BLE001 — keep Gradio toast away
            print(f"[app] predict() error: {e!r}")
            return "", f"*error during inference: {e}*"

    # --- UI callbacks ------------------------------------------------------

    def on_refresh():
        choices = _dropdown_choices()
        return gr.update(choices=choices, value=_current_value()), _status_md()

    def on_load(dropdown_value: str | None, custom_path: str):
        target = (custom_path or "").strip() or dropdown_value
        if not target:
            return gr.update(), _status_md(), "Pick a model folder or paste a path first."
        try:
            load_model(Path(target))
        except Exception as e:  # noqa: BLE001
            return gr.update(), _status_md(), f"Load failed: {e}"
        choices = _dropdown_choices()
        return (
            gr.update(choices=choices, value=_current_value()),
            _status_md(),
            f"Loaded `{Path(target).name}`.",
        )

    def on_download(variant: str, progress=gr.Progress(track_tqdm=True)):
        if not variant:
            return gr.update(), _status_md(), "Pick a variant first."
        try:
            from huggingface_hub import snapshot_download
        except ImportError:
            return (
                gr.update(),
                _status_md(),
                "huggingface_hub is not installed — re-run `app.py --reinstall`.",
            )
        progress(0, desc=f"Downloading {variant} from {HF_REPO_ID} ...")
        try:
            snapshot_download(
                repo_id=HF_REPO_ID,
                allow_patterns=[f"{variant}/*"],
                local_dir=str(ROOT),
            )
        except Exception as e:  # noqa: BLE001
            return gr.update(), _status_md(), f"Download failed: {e}"

        target = ROOT / variant
        msg = f"Downloaded `{variant}`."
        if all((target / f).exists() for f in REQUIRED_FILES):
            try:
                load_model(target)
                msg += f" Loaded `{variant}`."
            except Exception as e:  # noqa: BLE001
                msg += f" Load failed: {e}"
        choices = _dropdown_choices()
        return gr.update(choices=choices, value=_current_value()), _status_md(), msg

    # --- UI layout ---------------------------------------------------------

    with gr.Blocks(title="Oppai ONNX Tagger") as demo:
        gr.Markdown(
            "# Oppai ONNX Tagger\n"
            "Upload an image and tweak the threshold / max tags. "
            "Pick a model below or download one from "
            "[Grio43/OppaiOracle](https://huggingface.co/Grio43/OppaiOracle)."
        )

        with gr.Accordion("Model", open=True):
            with gr.Row():
                model_dd = gr.Dropdown(
                    choices=_dropdown_choices(),
                    value=_current_value(),
                    label="Detected model folders (next to app.py)",
                    interactive=True,
                    scale=3,
                )
                refresh_btn = gr.Button("Refresh", scale=1)
            with gr.Row():
                custom_path = gr.Textbox(
                    label="…or paste a custom model folder path (overrides dropdown)",
                    placeholder=r"e.g. C:\models\my_onnx_folder",
                    scale=4,
                )
                load_btn = gr.Button("Load", variant="primary", scale=1)
            with gr.Row():
                hf_dd = gr.Dropdown(
                    choices=HF_VARIANTS,
                    value=HF_VARIANTS[0],
                    label=f"Download a variant from {HF_REPO_ID}",
                    scale=3,
                )
                download_btn = gr.Button("Download", scale=1)
            status_md = gr.Markdown(_status_md())
            action_msg = gr.Markdown("")

        with gr.Row():
            with gr.Column(scale=1):
                inp = gr.Image(type="pil", label="Image", height=448)
                threshold = gr.Slider(
                    0.0, 1.0,
                    value=0.35,
                    step=0.005,
                    label="Threshold (interactive default 0.35; calibrated breakeven shown above)",
                )
                max_tags = gr.Slider(1, 200, value=50, step=1, label="Max tags")
                cats = gr.CheckboxGroup(
                    choices=list(cat_names.values()),
                    value=list(cat_names.values()),
                    label="Categories to include",
                )
                btn = gr.Button("Tag image", variant="primary")
            with gr.Column(scale=1):
                tags_out = gr.Textbox(
                    label="Tags (comma-separated, underscores → spaces)",
                    lines=5,
                )
                table_out = gr.Markdown(label="Per-tag detail")

        refresh_btn.click(on_refresh, outputs=[model_dd, status_md])
        load_btn.click(on_load, inputs=[model_dd, custom_path], outputs=[model_dd, status_md, action_msg])
        download_btn.click(on_download, inputs=[hf_dd], outputs=[model_dd, status_md, action_msg])

        ev_inputs = [inp, threshold, max_tags, cats]
        ev_outputs = [tags_out, table_out]
        btn.click(predict, ev_inputs, ev_outputs)
        inp.change(predict, ev_inputs, ev_outputs)
        threshold.release(predict, ev_inputs, ev_outputs)
        max_tags.release(predict, ev_inputs, ev_outputs)
        cats.change(predict, ev_inputs, ev_outputs)

    # CPU inference is ~1-3s per image; cap concurrency so spammed slider
    # changes queue serially instead of fighting for the same model session.
    demo.queue(default_concurrency_limit=1).launch(
        server_name="127.0.0.1", server_port=7860, inbrowser=True
    )


# ---------------------------------------------------------------------------
# Entrypoint
# ---------------------------------------------------------------------------

def main() -> None:
    # On Windows, the console codepage is often cp1252/cp932/etc., not UTF-8.
    # Our messages contain em-dashes and × — `errors="replace"` keeps them from
    # crashing the bootstrap with UnicodeEncodeError on those consoles.
    for stream in (sys.stdout, sys.stderr):
        try:
            stream.reconfigure(errors="replace")
        except (AttributeError, OSError):
            pass

    force = "--reinstall" in sys.argv[1:]

    if _running_portable_python():
        # run.bat downloaded an embeddable Python because the user had none.
        # Install requirements directly into it; no venv re-exec needed.
        _bootstrap_portable(force_reinstall=force)
        _run_app()
        return

    if not _in_target_venv():
        _bootstrap(force_reinstall=force)
        return  # _bootstrap re-execs and exits
    _run_app()


if __name__ == "__main__":
    main()