import os
import platform
import shutil
import subprocess

# ------------------------- helpers -------------------------


def _run(cmd, timeout=3):
    """Run a command safely. Returns stdout text or ''.
    Accepts either a string (shell) or list (no shell)."""
    try:
        if isinstance(cmd, str):
            return subprocess.check_output(
                cmd, shell=True, text=True, stderr=subprocess.DEVNULL, timeout=timeout
            ).strip()
        else:
            return subprocess.check_output(
                cmd, shell=False, text=True, stderr=subprocess.DEVNULL, timeout=timeout
            ).strip()
    except Exception:
        return ""


def _first_line(s: str) -> str:
    s = (s or "").strip()
    return s.splitlines()[0].strip() if s else ""


def _which(name: str) -> str:
    return shutil.which(name) or ""


def _bool_from_output(s: str) -> bool:
    return s.strip() in {"1", "true", "True", "YES", "Yes", "yes"}


# ------------------------- OS & env -------------------------


def _os_block():
    sysname = platform.system()  # 'Windows', 'Darwin', 'Linux'
    machine = platform.machine() or ""
    release = platform.release() or ""
    version = platform.version() or ""
    kernel = release if sysname == "Windows" else (_run(["uname", "-r"]) or release)

    distro = {"name": "", "version": ""}
    if sysname == "Linux":
        # Best-effort parse of /etc/os-release
        try:
            with open("/etc/os-release", "r") as f:
                data = {}
                for line in f:
                    if "=" in line:
                        k, v = line.rstrip().split("=", 1)
                        data[k] = v.strip('"')
                distro["name"] = data.get("PRETTY_NAME") or data.get("NAME", "")
                distro["version"] = data.get("VERSION_ID") or data.get("VERSION", "")
        except Exception:
            pass

    # WSL / Rosetta detection (harmless if not present)
    wsl = False
    if sysname != "Windows":
        try:
            with open("/proc/version", "r") as f:
                v = f.read().lower()
                wsl = ("microsoft" in v) or ("wsl" in v)
        except Exception:
            wsl = False

    rosetta = False
    if sysname == "Darwin":
        rosetta = _bool_from_output(_run(["sysctl", "-in", "sysctl.proc_translated"]))

    # Target triple (best effort)
    target = ""
    for cc in ("clang", "gcc"):
        if _which(cc):
            out = _run([cc, "-dumpmachine"])
            if out:
                target = _first_line(out)
                break

    return {
        "system": sysname,
        "arch": machine,
        "release": release,
        "version": version,
        "kernel": kernel,
        "distro": distro if sysname == "Linux" else None,
        "wsl": wsl,
        "rosetta2_translated": rosetta,
        "target_triple": target,
    }


# ------------------------- package managers -------------------------


def _package_managers():
    sysname = platform.system()
    pms = []
    if sysname == "Windows":
        for pm in ("winget", "choco", "scoop"):
            if _which(pm):
                pms.append(pm)
    elif sysname == "Darwin":
        if _run(["xcode-select", "-p"]):
            pms.append("xcode-select (CLT)")
        for pm in ("brew", "port"):
            if _which(pm):
                pms.append(pm)
    else:
        for pm in ("apt", "dnf", "yum", "pacman", "zypper", "apk", "emerge"):
            if _which(pm):
                pms.append(pm)
    return pms


# ------------------------- CPU (minimal) -------------------------


def _cpu_block():
    sysname = platform.system()
    brand = ""
    # A simple brand/model read per OS; ignore failures
    if sysname == "Linux":
        brand = _run("grep -m1 'model name' /proc/cpuinfo | cut -d: -f2").strip()
    elif sysname == "Darwin":
        brand = _run(["sysctl", "-n", "machdep.cpu.brand_string"])
    elif sysname == "Windows":
        brand = _run('powershell -NoProfile -Command "(Get-CimInstance Win32_Processor).Name"')
        if not brand:
            brand = _run("wmic cpu get Name /value").replace("Name=", "").strip()

    # Logical cores always available; physical is best-effort
    cores_logical = os.cpu_count() or 0
    cores_physical = 0
    if sysname == "Darwin":
        cores_physical = int(_run(["sysctl", "-n", "hw.physicalcpu"]) or "0")
    elif sysname == "Windows":
        cores_physical = int(
            _run('powershell -NoProfile -Command "(Get-CimInstance Win32_Processor).NumberOfCores"')
            or "0"
        )
    elif sysname == "Linux":
        # This is a quick approximation; fine for our use (parallel -j suggestions)
        try:
            # Count unique "core id" per physical id
            mapping = _run("LC_ALL=C lscpu -p=CORE,SOCKET | grep -v '^#'").splitlines()
            unique = set(tuple(line.split(",")) for line in mapping if "," in line)
            cores_physical = len(unique) or 0
        except Exception:
            cores_physical = 0

    # A tiny SIMD hint set (best-effort, optional)
    simd = []
    if sysname == "Linux":
        flags = _run("grep -m1 'flags' /proc/cpuinfo | cut -d: -f2")
        if flags:
            fset = set(flags.upper().split())
            for x in ("AVX512F", "AVX2", "AVX", "FMA", "SSE4_2", "NEON", "SVE"):
                if x in fset:
                    simd.append(x)
    elif sysname == "Darwin":
        feats = (
            (
                _run(["sysctl", "-n", "machdep.cpu.features"])
                + " "
                + _run(["sysctl", "-n", "machdep.cpu.leaf7_features"])
            )
            .upper()
            .split()
        )
        for x in ("AVX512F", "AVX2", "AVX", "FMA", "SSE4_2", "NEON", "SVE"):
            if x in feats:
                simd.append(x)
    # On Windows, skip flags — brand typically suffices for MSVC /arch choice.

    return {
        "brand": brand.strip(),
        "cores_logical": cores_logical,
        "cores_physical": cores_physical,
        "simd": sorted(set(simd)),
    }


# ------------------------- toolchain presence -------------------------


def _toolchain_block():
    def ver_line(exe, args=("--version",)):
        p = _which(exe)
        if not p:
            return ""
        out = _run([p, *args])
        return _first_line(out)

    gcc = ver_line("gcc")
    gpp = ver_line("g++")
    clang = ver_line("clang")

    # MSVC cl (only available inside proper dev shell; handle gracefully)
    msvc_cl = ""
    cl_path = _which("cl")
    if cl_path:
        msvc_cl = _first_line(_run("cl 2>&1"))

    # Build tools (presence + short version line)
    cmake = ver_line("cmake")
    ninja = _first_line(_run([_which("ninja"), "--version"])) if _which("ninja") else ""
    make = ver_line("make")

    # Linker (we only care if lld is available)
    lld = ver_line("ld.lld")
    return {
        "compilers": {"gcc": gcc, "g++": gpp, "clang": clang, "msvc_cl": msvc_cl},
        "build_tools": {"cmake": cmake, "ninja": ninja, "make": make},
        "linkers": {"ld_lld": lld},
    }


# ------------------------- public API -------------------------


def retrieve_system_info():
    """
    Returns a compact dict with enough info for an LLM to:
      - Pick an install path (winget/choco/scoop, Homebrew/Xcode CLT, apt/dnf/...),
      - Choose a compiler family (MSVC/clang/gcc),
      - Suggest safe optimization flags (e.g., -O3/-march=native or MSVC /O2),
      - Decide on a build system (cmake+ninja) and parallel -j value.
    """
    return {
        "os": _os_block(),
        "package_managers": _package_managers(),
        "cpu": _cpu_block(),
        "toolchain": _toolchain_block(),
    }


def rust_toolchain_info():
    """
    Return a dict with Rust-related settings:
      - presence and paths for rustc / cargo / rustup / rust-analyzer
      - versions
      - active/default toolchain (if rustup is present)
      - installed targets
      - common env vars (CARGO_HOME, RUSTUP_HOME, RUSTFLAGS, CARGO_BUILD_TARGET)
      - simple execution examples
    Works on Windows, macOS, and Linux. Uses the existing helpers: _run, _which, _first_line.
    """
    info = {
        "installed": False,
        "rustc": {"path": "", "version": "", "host_triple": "", "release": "", "commit_hash": ""},
        "cargo": {"path": "", "version": ""},
        "rustup": {
            "path": "",
            "version": "",
            "active_toolchain": "",
            "default_toolchain": "",
            "toolchains": [],
            "targets_installed": [],
        },
        "rust_analyzer": {"path": ""},
        "env": {
            "CARGO_HOME": os.environ.get("CARGO_HOME", ""),
            "RUSTUP_HOME": os.environ.get("RUSTUP_HOME", ""),
            "RUSTFLAGS": os.environ.get("RUSTFLAGS", ""),
            "CARGO_BUILD_TARGET": os.environ.get("CARGO_BUILD_TARGET", ""),
        },
        "execution_examples": [],
    }

    # Paths
    rustc_path = _which("rustc")
    cargo_path = _which("cargo")
    rustup_path = _which("rustup")
    ra_path = _which("rust-analyzer")

    info["rustc"]["path"] = rustc_path or ""
    info["cargo"]["path"] = cargo_path or ""
    info["rustup"]["path"] = rustup_path or ""
    info["rust_analyzer"]["path"] = ra_path or ""

    # Versions & verbose details
    if rustc_path:
        ver_line = _first_line(_run([rustc_path, "--version"]))
        info["rustc"]["version"] = ver_line
        verbose = _run([rustc_path, "--version", "--verbose"])
        host = release = commit = ""
        for line in verbose.splitlines():
            if line.startswith("host:"):
                host = line.split(":", 1)[1].strip()
            elif line.startswith("release:"):
                release = line.split(":", 1)[1].strip()
            elif line.startswith("commit-hash:"):
                commit = line.split(":", 1)[1].strip()
        info["rustc"]["host_triple"] = host
        info["rustc"]["release"] = release
        info["rustc"]["commit_hash"] = commit

    if cargo_path:
        info["cargo"]["version"] = _first_line(_run([cargo_path, "--version"]))

    if rustup_path:
        info["rustup"]["version"] = _first_line(_run([rustup_path, "--version"]))
        # Active toolchain
        active = _first_line(_run([rustup_path, "show", "active-toolchain"]))
        info["rustup"]["active_toolchain"] = active

        # Default toolchain (best effort)
        # Try parsing `rustup toolchain list` and pick the line with "(default)"
        tlist = _run([rustup_path, "toolchain", "list"]).splitlines()
        info["rustup"]["toolchains"] = [t.strip() for t in tlist if t.strip()]
        default_tc = ""
        for line in tlist:
            if "(default)" in line:
                default_tc = line.strip()
                break
        if not default_tc:
            # Fallback: sometimes `rustup show` includes "default toolchain: ..."
            for line in _run([rustup_path, "show"]).splitlines():
                if "default toolchain:" in line:
                    default_tc = line.split(":", 1)[1].strip()
                    break
        info["rustup"]["default_toolchain"] = default_tc

        # Installed targets
        targets = _run([rustup_path, "target", "list", "--installed"]).split()
        info["rustup"]["targets_installed"] = targets

    # Execution examples (only include what will work on this system)
    exec_examples = []
    if cargo_path:
        exec_examples.append(f'"{cargo_path}" build')
        exec_examples.append(f'"{cargo_path}" run')
        exec_examples.append(f'"{cargo_path}" test')
    if rustc_path:
        exec_examples.append(f'"{rustc_path}" hello.rs -o hello')
    info["execution_examples"] = exec_examples

    # Installed?
    info["installed"] = bool(rustc_path or cargo_path or rustup_path)

    # Fill in default homes if env vars are empty but typical locations exist
    def _maybe_default_home(env_val, default_basename):
        if env_val:
            return env_val
        home = os.path.expanduser("~") or ""
        candidate = os.path.join(home, default_basename) if home else ""
        return candidate if candidate and os.path.isdir(candidate) else ""

    info["env"]["CARGO_HOME"] = _maybe_default_home(info["env"]["CARGO_HOME"], ".cargo")
    info["env"]["RUSTUP_HOME"] = _maybe_default_home(info["env"]["RUSTUP_HOME"], ".rustup")

    return info