"""Filesystem operations — full access, no sandbox."""

import grp
import mimetypes
import os
import pwd
import shutil
import stat
from pathlib import Path
from typing import Optional

from fastapi import APIRouter, Depends, HTTPException, UploadFile, File, Query
from fastapi.responses import FileResponse
from pydantic import BaseModel

from backend.auth import get_current_user

router = APIRouter(prefix="/api/files", tags=["files"])


# ---------------------------------------------------------------------------
# Models
# ---------------------------------------------------------------------------

class FileInfo(BaseModel):
    name: str
    path: str
    is_dir: bool
    size: int
    modified: float
    permissions: str
    owner: str
    group: str
    mime: Optional[str] = None


class RenameRequest(BaseModel):
    old_path: str
    new_name: str


class MoveRequest(BaseModel):
    src: str
    dest: str


class MkdirRequest(BaseModel):
    path: str


class DeleteRequest(BaseModel):
    path: str


class WriteFileRequest(BaseModel):
    path: str
    content: str


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------

def _file_info(p: Path) -> FileInfo:
    try:
        st = p.stat()
    except OSError:
        st = p.lstat()

    try:
        owner = pwd.getpwuid(st.st_uid).pw_name
    except KeyError:
        owner = str(st.st_uid)

    try:
        group = grp.getgrgid(st.st_gid).gr_name
    except KeyError:
        group = str(st.st_gid)

    mime = None
    if p.is_file():
        mime = mimetypes.guess_type(str(p))[0]

    return FileInfo(
        name=p.name,
        path=str(p),
        is_dir=p.is_dir(),
        size=st.st_size,
        modified=st.st_mtime,
        permissions=stat.filemode(st.st_mode),
        owner=owner,
        group=group,
        mime=mime,
    )


# ---------------------------------------------------------------------------
# Endpoints
# ---------------------------------------------------------------------------

@router.get("/list")
async def list_dir(
    path: str = Query("/", description="Directory to list"),
    _user: str = Depends(get_current_user),
) -> list[FileInfo]:
    p = Path(path)
    if not p.is_dir():
        raise HTTPException(404, f"Not a directory: {path}")
    try:
        entries = sorted(p.iterdir(), key=lambda x: (not x.is_dir(), x.name.lower()))
    except PermissionError:
        raise HTTPException(403, f"Permission denied: {path}")
    return [_file_info(e) for e in entries]


@router.get("/info")
async def file_info(
    path: str = Query(...),
    _user: str = Depends(get_current_user),
) -> FileInfo:
    p = Path(path)
    if not p.exists():
        raise HTTPException(404, f"Not found: {path}")
    return _file_info(p)


@router.get("/read")
async def read_file(
    path: str = Query(...),
    _user: str = Depends(get_current_user),
):
    """Read a text file's contents."""
    p = Path(path)
    if not p.is_file():
        raise HTTPException(404, f"Not a file: {path}")
    try:
        content = p.read_text(errors="replace")
    except PermissionError:
        raise HTTPException(403, "Permission denied")
    return {"path": str(p), "content": content}


@router.get("/download")
async def download_file(
    path: str = Query(...),
    _user: str = Depends(get_current_user),
):
    """Download a file as binary."""
    p = Path(path)
    if not p.is_file():
        raise HTTPException(404, f"Not a file: {path}")
    return FileResponse(str(p), filename=p.name)


@router.post("/upload")
async def upload_file(
    dest_dir: str = Query(...),
    file: UploadFile = File(...),
    _user: str = Depends(get_current_user),
):
    dest = Path(dest_dir)
    if not dest.is_dir():
        raise HTTPException(404, f"Not a directory: {dest_dir}")
    target = dest / file.filename
    try:
        with open(target, "wb") as f:
            while chunk := await file.read(1024 * 1024):
                f.write(chunk)
    except PermissionError:
        raise HTTPException(403, "Permission denied")
    return {"path": str(target), "size": target.stat().st_size}


@router.post("/mkdir")
async def mkdir(req: MkdirRequest, _user: str = Depends(get_current_user)):
    p = Path(req.path)
    try:
        p.mkdir(parents=True, exist_ok=True)
    except PermissionError:
        raise HTTPException(403, "Permission denied")
    return {"path": str(p)}


@router.post("/rename")
async def rename(req: RenameRequest, _user: str = Depends(get_current_user)):
    src = Path(req.old_path)
    if not src.exists():
        raise HTTPException(404, f"Not found: {req.old_path}")
    dest = src.parent / req.new_name
    try:
        src.rename(dest)
    except PermissionError:
        raise HTTPException(403, "Permission denied")
    return {"path": str(dest)}


@router.post("/move")
async def move(req: MoveRequest, _user: str = Depends(get_current_user)):
    src = Path(req.src)
    dest = Path(req.dest)
    if not src.exists():
        raise HTTPException(404, f"Not found: {req.src}")
    try:
        shutil.move(str(src), str(dest))
    except PermissionError:
        raise HTTPException(403, "Permission denied")
    return {"path": str(dest)}


@router.post("/copy")
async def copy(req: MoveRequest, _user: str = Depends(get_current_user)):
    src = Path(req.src)
    dest = Path(req.dest)
    if not src.exists():
        raise HTTPException(404, f"Not found: {req.src}")
    try:
        if src.is_dir():
            shutil.copytree(str(src), str(dest))
        else:
            shutil.copy2(str(src), str(dest))
    except PermissionError:
        raise HTTPException(403, "Permission denied")
    return {"path": str(dest)}


@router.post("/delete")
async def delete(req: DeleteRequest, _user: str = Depends(get_current_user)):
    p = Path(req.path)
    if not p.exists():
        raise HTTPException(404, f"Not found: {req.path}")
    try:
        if p.is_dir():
            shutil.rmtree(str(p))
        else:
            p.unlink()
    except PermissionError:
        raise HTTPException(403, "Permission denied")
    return {"deleted": str(p)}


@router.post("/write")
async def write_file(req: WriteFileRequest, _user: str = Depends(get_current_user)):
    """Write/overwrite a text file."""
    p = Path(req.path)
    try:
        p.parent.mkdir(parents=True, exist_ok=True)
        p.write_text(req.content)
    except PermissionError:
        raise HTTPException(403, "Permission denied")
    return {"path": str(p), "size": p.stat().st_size}


@router.get("/mounts")
async def list_mounts(_user: str = Depends(get_current_user)):
    """List mounted filesystems."""
    mounts = []
    for part in __import__("psutil").disk_partitions(all=False):
        usage = __import__("psutil").disk_usage(part.mountpoint)
        mounts.append({
            "device": part.device,
            "mountpoint": part.mountpoint,
            "fstype": part.fstype,
            "total": usage.total,
            "used": usage.used,
            "percent": usage.percent,
        })
    return mounts