"""Package management — apt / dpkg wrapper for Debian-based systems."""

import asyncio
import logging
import os
import re
import shutil

from fastapi import APIRouter, Depends, HTTPException, Query
from pydantic import BaseModel

from backend.auth import get_current_user

router = APIRouter(prefix="/api/packages", tags=["packages"])
log = logging.getLogger("atlus.packages")

# ---------------------------------------------------------------------------
# Guard
# ---------------------------------------------------------------------------

def _find_apt():
    """Find apt binary, checking common paths if PATH is restricted."""
    for name in ("apt-cache", "apt"):
        if shutil.which(name):
            return True
    # systemd services may have a minimal PATH — check directly
    for p in ("/usr/bin/apt-cache", "/usr/bin/apt"):
        if os.path.isfile(p) and os.access(p, os.X_OK):
            return True
    return False


_HAS_APT = _find_apt()


def _require_apt():
    if not _HAS_APT:
        raise HTTPException(503, "apt package manager not available on this system")


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

_PKG_NAME_RE = re.compile(r"^[a-z0-9][a-z0-9.+\-:]+$")


def _validate_name(name: str) -> str:
    name = name.strip()
    if not _PKG_NAME_RE.match(name):
        raise HTTPException(400, f"Invalid package name: {name}")
    return name


def _safe_env():
    """Build environment with full PATH for apt/dpkg commands."""
    env = {**os.environ, "LC_ALL": "C", "DEBIAN_FRONTEND": "noninteractive"}
    # Ensure standard paths are included (systemd may use minimal PATH)
    path = env.get("PATH", "")
    for p in ("/usr/bin", "/usr/sbin", "/bin", "/sbin", "/usr/local/bin"):
        if p not in path:
            path = p + ":" + path
    env["PATH"] = path
    return env


async def _run_cmd(cmd: list[str], timeout: float = 30) -> tuple[int, str, str]:
    """Run a command, return (returncode, stdout, stderr). Never raises."""
    _require_apt()
    try:
        proc = await asyncio.create_subprocess_exec(
            *cmd,
            stdout=asyncio.subprocess.PIPE,
            stderr=asyncio.subprocess.PIPE,
            env=_safe_env(),
        )
    except FileNotFoundError as e:
        log.error("Command not found: %s — %s", cmd[0], e)
        return 127, "", f"Command not found: {cmd[0]}"

    try:
        stdout, stderr = await asyncio.wait_for(proc.communicate(), timeout=timeout)
    except asyncio.TimeoutError:
        proc.kill()
        await proc.wait()
        return 1, "", "Operation timed out"

    return proc.returncode, stdout.decode(errors="replace"), stderr.decode(errors="replace")


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

class PackageAction(BaseModel):
    name: str


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

@router.get("/search")
async def search_packages(
    q: str = Query(..., min_length=2, description="Search query"),
    _user: str = Depends(get_current_user),
):
    """Search for packages matching a query."""
    rc, stdout, stderr = await _run_cmd(["apt-cache", "search", q])

    # apt-cache search returns 0 even with no results — stderr warnings are normal
    if rc != 0:
        log.warning("apt-cache search failed (rc=%d): %s", rc, stderr.strip())
        raise HTTPException(500, f"Package search failed: {stderr.strip()[:200]}")

    if stderr.strip():
        log.debug("apt-cache search stderr (non-fatal): %s", stderr.strip()[:200])

    results = []
    for line in stdout.strip().splitlines():
        if not line.strip():
            continue
        parts = line.split(" - ", 1)
        if len(parts) == 2:
            results.append({"name": parts[0].strip(), "summary": parts[1].strip()})
        elif parts[0].strip():
            # Some lines may not have " - " separator
            results.append({"name": parts[0].strip(), "summary": ""})
        if len(results) >= 100:
            break
    return results


@router.get("/info/{name}")
async def package_info(
    name: str,
    _user: str = Depends(get_current_user),
):
    """Get detailed information about a package."""
    name = _validate_name(name)

    # Get package info from apt-cache
    rc, stdout, stderr = await _run_cmd(["apt-cache", "show", name])
    if rc != 0:
        log.warning("apt-cache show %s failed (rc=%d): %s", name, rc, stderr.strip())
        raise HTTPException(404, f"Package not found: {name}")

    # Parse key-value fields
    info = {}
    current_key = None
    current_val = ""
    for line in stdout.splitlines():
        if line.startswith(" "):
            # Continuation of previous field
            current_val += "\n" + line.strip()
        elif ": " in line:
            if current_key:
                info[current_key] = current_val
            current_key, current_val = line.split(": ", 1)
        elif line == "":
            if current_key:
                info[current_key] = current_val
                current_key = None
                current_val = ""
            break  # Only parse first stanza
    if current_key:
        info[current_key] = current_val

    # Check installed status via dpkg-query
    rc2, dpkg_out, _ = await _run_cmd(
        ["dpkg-query", "-W", "-f=${Status}\t${Version}\n", name]
    )
    installed_version = None
    is_installed = False
    if rc2 == 0 and dpkg_out.strip():
        parts = dpkg_out.strip().split("\t")
        if len(parts) >= 2 and "install ok installed" in parts[0]:
            is_installed = True
            installed_version = parts[1].strip()

    return {
        "name": info.get("Package", name),
        "version": info.get("Version", ""),
        "installed": is_installed,
        "installed_version": installed_version,
        "description": info.get("Description", info.get("Description-en", "")),
        "size": info.get("Size", ""),
        "installed_size": info.get("Installed-Size", ""),
        "depends": info.get("Depends", ""),
        "section": info.get("Section", ""),
        "maintainer": info.get("Maintainer", ""),
        "homepage": info.get("Homepage", ""),
        "architecture": info.get("Architecture", ""),
    }


@router.post("/install")
async def install_package(
    req: PackageAction,
    _user: str = Depends(get_current_user),
):
    """Install a package via apt-get."""
    name = _validate_name(req.name)
    rc, stdout, stderr = await _run_cmd(["apt-get", "install", "-y", name], timeout=300)
    if rc != 0:
        msg = stderr.strip() or stdout.strip()
        log.warning("apt-get install %s failed (rc=%d): %s", name, rc, msg[:200])
        raise HTTPException(500, f"Install failed: {msg[:300]}")
    return {"success": True, "package": name, "output": stdout[-500:]}


@router.post("/remove")
async def remove_package(
    req: PackageAction,
    _user: str = Depends(get_current_user),
):
    """Remove a package via apt-get."""
    name = _validate_name(req.name)
    rc, stdout, stderr = await _run_cmd(["apt-get", "remove", "-y", name], timeout=120)
    if rc != 0:
        msg = stderr.strip() or stdout.strip()
        log.warning("apt-get remove %s failed (rc=%d): %s", name, rc, msg[:200])
        raise HTTPException(500, f"Remove failed: {msg[:300]}")
    return {"success": True, "package": name, "output": stdout[-500:]}


@router.post("/update-cache")
async def update_cache(_user: str = Depends(get_current_user)):
    """Run apt-get update to refresh package lists."""
    rc, stdout, stderr = await _run_cmd(["apt-get", "update"], timeout=120)
    if rc != 0:
        msg = stderr.strip() or stdout.strip()
        log.warning("apt-get update failed (rc=%d): %s", rc, msg[:200])
        raise HTTPException(500, f"Cache update failed: {msg[:300]}")
    return {"success": True, "output": stdout[-500:]}


@router.get("/debug")
async def debug_apt(_user: str = Depends(get_current_user)):
    """Debug endpoint — test apt-cache availability."""
    results = {
        "has_apt": _HAS_APT,
        "which_apt_cache": shutil.which("apt-cache"),
        "which_apt": shutil.which("apt"),
        "which_dpkg": shutil.which("dpkg-query"),
        "path": os.environ.get("PATH", ""),
        "safe_path": _safe_env().get("PATH", ""),
    }

    # Try running apt-cache directly
    for cmd_path in ["/usr/bin/apt-cache", "apt-cache"]:
        try:
            proc = await asyncio.create_subprocess_exec(
                cmd_path, "search", "bash",
                stdout=asyncio.subprocess.PIPE,
                stderr=asyncio.subprocess.PIPE,
                env=_safe_env(),
            )
            stdout, stderr = await asyncio.wait_for(proc.communicate(), timeout=10)
            lines = stdout.decode(errors="replace").strip().splitlines()
            results[f"test_{cmd_path}"] = {
                "rc": proc.returncode,
                "stdout_lines": len(lines),
                "first_line": lines[0] if lines else "",
                "stderr": stderr.decode(errors="replace").strip()[:200],
            }
        except Exception as e:
            results[f"test_{cmd_path}"] = {"error": str(e)}

    return results