# SPDX-License-Identifier: AGPL-3.0-only
# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0

"""
Main FastAPI application for Unsloth UI Backend
"""

import os
import sys
from pathlib import Path as _Path

# Suppress annoying C-level dependency warnings globally
os.environ["PYTHONWARNINGS"] = "ignore"

# Ensure backend dir is on sys.path so _platform_compat is importable when
# main.py is launched directly (e.g. `uvicorn main:app`).
_backend_dir = str(_Path(__file__).parent)
if _backend_dir not in sys.path:
    sys.path.insert(0, _backend_dir)

# Fix for Anaconda/conda-forge Python: seed platform._sys_version_cache before
# any library imports that trigger attrs -> rich -> structlog -> platform crash.
# See: https://github.com/python/cpython/issues/102396
import _platform_compat  # noqa: F401

import mimetypes
import shutil
import warnings
from contextlib import asynccontextmanager
from importlib.metadata import PackageNotFoundError, version as package_version

# Fix broken Windows registry MIME types.  Some Windows installs map .js to
# "text/plain" in the registry (HKCR\.js\Content Type).  Python's mimetypes
# module reads from the registry, and FastAPI/Starlette's StaticFiles uses
# mimetypes.guess_type() to set Content-Type headers.  Browsers enforce strict
# MIME checking for ES module scripts (<script type="module">) and will refuse
# to execute .js files served as text/plain — resulting in a blank page.
# Calling add_type() *before* StaticFiles is instantiated ensures the correct
# types are used regardless of the OS registry.
if sys.platform == "win32":
    mimetypes.add_type("application/javascript", ".js")
    mimetypes.add_type("text/css", ".css")

# Suppress annoying dependency warnings in production
if os.getenv("ENVIRONMENT_TYPE", "production") == "production":
    warnings.filterwarnings("ignore")
    # Alternatively, you can be more specific:
    # warnings.filterwarnings("ignore", category=DeprecationWarning)
    # warnings.filterwarnings("ignore", module="triton.*")

from fastapi import Depends, FastAPI, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles
from fastapi.responses import FileResponse, HTMLResponse, Response
from pathlib import Path
from datetime import datetime

# Import routers
from routes import (
    auth_router,
    data_recipe_router,
    datasets_router,
    export_router,
    inference_router,
    models_router,
    training_history_router,
    training_router,
)
from auth import storage
from auth.authentication import get_current_subject
from utils.hardware import (
    detect_hardware,
    get_device,
    DeviceType,
    get_backend_visible_gpu_info,
)
import utils.hardware.hardware as _hw_module

from utils.cache_cleanup import clear_unsloth_compiled_cache


def get_unsloth_version() -> str:
    try:
        return package_version("unsloth")
    except PackageNotFoundError:
        pass

    version_file = (
        _Path(__file__).resolve().parents[2] / "unsloth" / "models" / "_utils.py"
    )
    try:
        for line in version_file.read_text(encoding = "utf-8").splitlines():
            if line.startswith("__version__ = "):
                return line.split("=", 1)[1].strip().strip('"').strip("'")
    except OSError:
        pass
    return "dev"


UNSLOTH_VERSION = get_unsloth_version()


@asynccontextmanager
async def lifespan(app: FastAPI):
    """Startup: detect hardware, seed default admin if needed. Shutdown: clean up compiled cache."""
    # Clean up any stale compiled cache from previous runs
    clear_unsloth_compiled_cache()

    # Remove stale .venv_overlay from previous versions — no longer used.
    # Version switching now uses .venv_t5/ (pre-installed by setup.sh).
    overlay_dir = Path(__file__).resolve().parent.parent.parent / ".venv_overlay"
    if overlay_dir.is_dir():
        shutil.rmtree(overlay_dir, ignore_errors = True)

    # Detect hardware first — sets DEVICE global used everywhere
    detect_hardware()

    from storage.studio_db import cleanup_orphaned_runs

    try:
        cleanup_orphaned_runs()
    except Exception as exc:
        import structlog

        structlog.get_logger(__name__).warning(
            "cleanup_orphaned_runs failed at startup: %s", exc
        )

    # Pre-cache the helper GGUF model for LLM-assisted dataset detection.
    # Runs in a background thread so it doesn't block server startup.
    import threading

    def _precache():
        try:
            from utils.datasets.llm_assist import precache_helper_gguf

            precache_helper_gguf()
        except Exception:
            pass  # non-critical

    threading.Thread(target = _precache, daemon = True).start()

    if storage.ensure_default_admin():
        bootstrap_pw = storage.get_bootstrap_password()
        app.state.bootstrap_password = bootstrap_pw

        bootstrap_path = storage.DB_PATH.parent / ".bootstrap_password"
        print("\n" + "=" * 60)
        print("DEFAULT ADMIN ACCOUNT CREATED")
        print(f"    username: {storage.DEFAULT_ADMIN_USERNAME}")
        print(f"    password saved to: {bootstrap_path}")
        print("    Open the Studio UI to sign in and change it.")
        print("=" * 60 + "\n")
    else:
        app.state.bootstrap_password = storage.get_bootstrap_password()
    yield
    # Cleanup
    _hw_module.DEVICE = None
    clear_unsloth_compiled_cache()


# Create FastAPI app
app = FastAPI(
    title = "Unsloth UI Backend",
    version = UNSLOTH_VERSION,
    description = "Backend API for Unsloth UI - Training and Model Management",
    lifespan = lifespan,
)

# Initialize structured logging
from loggers.config import LogConfig
from loggers.handlers import LoggingMiddleware

logger = LogConfig.setup_logging(
    service_name = "unsloth-studio-backend",
    env = os.getenv("ENVIRONMENT_TYPE", "production"),
)

app.add_middleware(LoggingMiddleware)

# CORS middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins = ["*"],  # In production, specify allowed origins
    allow_credentials = True,
    allow_methods = ["*"],
    allow_headers = ["*"],
)

# ============ Register API Routes ============

# Register routers
app.include_router(auth_router, prefix = "/api/auth", tags = ["auth"])
app.include_router(training_router, prefix = "/api/train", tags = ["training"])
app.include_router(models_router, prefix = "/api/models", tags = ["models"])
app.include_router(inference_router, prefix = "/api/inference", tags = ["inference"])

# OpenAI-compatible endpoints: mount the same inference router at /v1
# so external tools (Open WebUI, SillyTavern, etc.) can use the
# standard /v1/chat/completions path.
app.include_router(inference_router, prefix = "/v1", tags = ["openai-compat"])
app.include_router(datasets_router, prefix = "/api/datasets", tags = ["datasets"])
app.include_router(data_recipe_router, prefix = "/api/data-recipe", tags = ["data-recipe"])
app.include_router(export_router, prefix = "/api/export", tags = ["export"])
app.include_router(
    training_history_router, prefix = "/api/train", tags = ["training-history"]
)


# ============ Health and System Endpoints ============


@app.get("/api/health")
async def health_check():
    """Health check endpoint"""
    platform_map = {"darwin": "mac", "win32": "windows", "linux": "linux"}
    device_type = platform_map.get(sys.platform, sys.platform)

    return {
        "status": "healthy",
        "timestamp": datetime.now().isoformat(),
        "service": "Unsloth UI Backend",
        "version": UNSLOTH_VERSION,
        "device_type": device_type,
        "chat_only": _hw_module.CHAT_ONLY,
    }


@app.post("/api/shutdown")
async def shutdown_server(
    request: Request,
    current_subject: str = Depends(get_current_subject),
):
    """Gracefully shut down the Unsloth Studio server.

    Called by the frontend quit dialog so users can stop the server from the UI
    without needing to use the CLI or kill the process manually.
    """
    import asyncio

    async def _delayed_shutdown():
        await asyncio.sleep(0.2)  # Let the HTTP response return first
        trigger = getattr(request.app.state, "trigger_shutdown", None)
        if trigger is not None:
            trigger()
        else:
            # Fallback when not launched via run_server() (e.g. direct uvicorn)
            import signal
            import os

            os.kill(os.getpid(), signal.SIGTERM)

    request.app.state._shutdown_task = asyncio.create_task(_delayed_shutdown())
    return {"status": "shutting_down"}


@app.get("/api/system")
async def get_system_info():
    """Get system information"""
    import platform
    import psutil
    from utils.hardware import get_device
    from utils.hardware.hardware import _backend_label

    visibility_info = get_backend_visible_gpu_info()
    gpu_info = {
        "available": visibility_info["available"],
        "devices": visibility_info["devices"],
    }

    # CPU & Memory
    memory = psutil.virtual_memory()

    return {
        "platform": platform.platform(),
        "python_version": platform.python_version(),
        # Use the centralized _backend_label helper so the /api/system
        # endpoint reports "rocm" on AMD hosts instead of "cuda", matching
        # the /api/hardware and /api/gpu-visibility endpoints.
        "device_backend": _backend_label(get_device()),
        "cpu_count": psutil.cpu_count(),
        "memory": {
            "total_gb": round(memory.total / 1e9, 2),
            "available_gb": round(memory.available / 1e9, 2),
            "percent_used": memory.percent,
        },
        "gpu": gpu_info,
    }


@app.get("/api/system/gpu-visibility")
async def get_gpu_visibility(
    current_subject: str = Depends(get_current_subject),
):
    return get_backend_visible_gpu_info()


@app.get("/api/system/hardware")
async def get_hardware_info():
    """Return GPU name, total VRAM, and key ML package versions."""
    from utils.hardware import get_gpu_summary, get_package_versions

    return {
        "gpu": get_gpu_summary(),
        "versions": get_package_versions(),
    }


# ============ Serve Frontend (Optional) ============


def _strip_crossorigin(html_bytes: bytes) -> bytes:
    """Remove ``crossorigin`` attributes from script/link tags.

    Vite adds ``crossorigin`` by default which forces CORS mode on font
    subresource loads.  When Studio is served over plain HTTP, Firefox
    HTTPS-Only Mode does not exempt CORS font requests -- causing all
    @font-face downloads to fail silently.  Stripping the attribute
    makes them regular same-origin fetches that work on any protocol.
    """
    import re as _re

    html = html_bytes.decode("utf-8")
    html = _re.sub(r'\s+crossorigin(?:="[^"]*")?', "", html)
    return html.encode("utf-8")


def _inject_bootstrap(html_bytes: bytes, app: FastAPI) -> bytes:
    """Inject bootstrap credentials into HTML when password change is required.

    The script tag is only injected while the default admin account still
    has ``must_change_password=True``.  Once the user changes the password
    the HTML is served clean — no credentials leak.
    """
    import json as _json

    if not storage.requires_password_change(storage.DEFAULT_ADMIN_USERNAME):
        return html_bytes

    bootstrap_pw = getattr(app.state, "bootstrap_password", None)
    if not bootstrap_pw:
        return html_bytes

    payload = _json.dumps(
        {
            "username": storage.DEFAULT_ADMIN_USERNAME,
            "password": bootstrap_pw,
        }
    )
    tag = f"<script>window.__UNSLOTH_BOOTSTRAP__={payload}</script>"
    html = html_bytes.decode("utf-8")
    html = html.replace("</head>", f"{tag}</head>", 1)
    return html.encode("utf-8")


def setup_frontend(app: FastAPI, build_path: Path):
    """Mount frontend static files (optional)"""
    if not build_path.exists():
        return False

    # Mount assets
    assets_dir = build_path / "assets"
    if assets_dir.exists():
        app.mount("/assets", StaticFiles(directory = assets_dir), name = "assets")

    @app.get("/")
    async def serve_root():
        content = (build_path / "index.html").read_bytes()
        content = _strip_crossorigin(content)
        content = _inject_bootstrap(content, app)
        return Response(
            content = content,
            media_type = "text/html",
            headers = {"Cache-Control": "no-cache, no-store, must-revalidate"},
        )

    @app.get("/{full_path:path}")
    async def serve_frontend(full_path: str):
        if full_path in {"api", "v1"} or full_path.startswith(("api/", "v1/")):
            return {"error": "API endpoint not found"}

        file_path = (build_path / full_path).resolve()

        # Block path traversal — ensure resolved path stays inside build_path
        if not file_path.is_relative_to(build_path.resolve()):
            return Response(status_code = 403)

        if file_path.is_file():
            return FileResponse(file_path)

        # Serve index.html as bytes — avoids Content-Length mismatch
        content = (build_path / "index.html").read_bytes()
        content = _strip_crossorigin(content)
        content = _inject_bootstrap(content, app)
        return Response(
            content = content,
            media_type = "text/html",
            headers = {"Cache-Control": "no-cache, no-store, must-revalidate"},
        )

    return True