fieldlens-desktop/src-tauri/src/printers.rs

use std::process::Command;

#[cfg(target_os = "windows")]
use std::os::windows::process::CommandExt;

#[cfg(any(target_os = "windows", target_os = "linux"))]
use std::fs;
#[cfg(target_os = "linux")]
use std::path::{Path, PathBuf};

use anyhow::{anyhow, Context, Result};
use serde::{Deserialize, Serialize};
#[cfg(target_os = "windows")]
use serde_json::Value;

pub const VIRTUAL_PRINTER_NAME: &str = "FieldLens Print";
#[cfg(target_os = "linux")]
pub const TEST_VIRTUAL_PRINTER_NAME: &str = "FieldLens Test Capture";
#[cfg(target_os = "linux")]
const TEST_VIRTUAL_PRINTER_QUEUE: &str = "FieldLens-Test-Capture";
#[cfg(target_os = "linux")]
const TEST_CAPTURE_DEVICE_URI: &str = "socket://127.0.0.1:9101";
const WINDOWS_PORT_NAME: &str = "FieldLensPrint-9100";
#[cfg(target_os = "windows")]
const CREATE_NO_WINDOW: u32 = 0x08000000;

#[cfg(target_os = "windows")]
fn hidden_windows_command(program: &str) -> Command {
    let mut command = Command::new(program);
    command.creation_flags(CREATE_NO_WINDOW);
    command
}

#[cfg(target_os = "linux")]
const FIELDLENS_CUPS_SPOOL_DIR: &str = "/var/lib/fieldlens-print/capture";
#[cfg(target_os = "linux")]
const FIELDLENS_CUPS_FILTER: &str = r#"#!/usr/bin/python3
import os
import re
import sys

CACHE = "/var/lib/fieldlens-print/capture"
OWNER_UID = __FIELDLENS_OWNER_UID__
OWNER_GID = __FIELDLENS_OWNER_GID__

def safe(value):
    value = re.sub(r"[^A-Za-z0-9._-]+", "-", value or "job").strip("-")
    return value[:80] or "job"

job_id = safe(sys.argv[1] if len(sys.argv) > 1 else "job")
title = safe(sys.argv[3] if len(sys.argv) > 3 else "print")
printer = safe(os.environ.get("PRINTER", "printer"))
prefix = "test-" if printer.lower() == "fieldlens-test-capture" else "print-"
suffix = "" if title.lower().endswith(".pdf") else ".pdf"
name = f"{prefix}{printer}-{job_id}-{title}{suffix}"
final_path = os.path.join(CACHE, name)
part_path = final_path + ".part"

source = None
capture = None
captured_ok = False

try:
    if len(sys.argv) > 6 and sys.argv[6]:
        source = open(sys.argv[6], "rb")
    else:
        source = sys.stdin.buffer

    try:
        os.makedirs(CACHE, exist_ok=True)
        if not os.path.exists(final_path):
            capture = open(part_path, "wb")
    except OSError as error:
        print(f"WARNING: FieldLens capture cache unavailable: {error}", file=sys.stderr)
        capture = None

    while True:
        chunk = source.read(65536)
        if not chunk:
            break

        if capture is not None:
            try:
                capture.write(chunk)
            except OSError as error:
                print(f"WARNING: FieldLens capture write failed: {error}", file=sys.stderr)
                try:
                    capture.close()
                except OSError:
                    pass
                capture = None

        sys.stdout.buffer.write(chunk)

    sys.stdout.buffer.flush()

    if capture is not None:
        capture.flush()
        capture.close()
        capture = None
        os.chmod(part_path, 0o600)
        try:
            os.chown(part_path, OWNER_UID, OWNER_GID)
        except PermissionError:
            # On this Linux lane CUPS runs filters as root. Keep printing alive
            # if a future CUPS policy drops privileges; repair can surface it.
            pass
        os.replace(part_path, final_path)
        captured_ok = True
        print(f"INFO: FieldLens captured {name}", file=sys.stderr)
finally:
    if source is not None and source is not sys.stdin.buffer:
        source.close()
    if capture is not None:
        capture.close()
    if not captured_ok:
        try:
            os.unlink(part_path)
        except OSError:
            pass
"#;

#[cfg(target_os = "linux")]
fn render_linux_capture_filter(uid: &str, gid: &str) -> String {
    FIELDLENS_CUPS_FILTER
        .replace("__FIELDLENS_OWNER_UID__", uid)
        .replace("__FIELDLENS_OWNER_GID__", gid)
}

#[cfg(target_os = "linux")]
const FIELDLENS_CUPS_REPAIR_HELPER: &str = r#"#!/usr/bin/python3
import os
import subprocess
import sys
import tempfile

target_printer = sys.argv[1]
target_port = sys.argv[2]
temp_filter = sys.argv[3]
filter_path = sys.argv[4]
owner_uid = int(sys.argv[5])
owner_gid = int(sys.argv[6])

source_ppd = os.path.join("/etc/cups/ppd", f"{target_printer}.ppd")
spool_dir = "/var/lib/fieldlens-print/capture"
old_spool_dir = "/var/cache/cups/fieldlens-print"

with open(source_ppd, "r", encoding="utf-8", errors="replace") as source:
    original = source.read()

cleaned = "\n".join(
    line for line in original.splitlines()
    if "fieldlens-capture" not in line
) + "\n"

prefilter = (
    "*% FieldLens original-document capture before cups-filters universal conversion\n"
    "*cupsPreFilter: \"application/vnd.universal-input 0 fieldlens-capture\"\n"
)

index = cleaned.rfind("*% End")
if index >= 0:
    cleaned = cleaned[:index] + prefilter + cleaned[index:]
else:
    cleaned += prefilter

fd, ppd_path = tempfile.mkstemp(prefix="fieldlens-", suffix=".ppd")
os.close(fd)

try:
    with open(ppd_path, "w", encoding="utf-8") as target:
        target.write(cleaned)

    subprocess.run(["install", "-m", "0755", temp_filter, filter_path], check=True)

    os.makedirs(spool_dir, exist_ok=True)
    os.chown(spool_dir, owner_uid, owner_gid)
    os.chmod(spool_dir, 0o700)

    # Bring forward captures stranded by 0.1.13/0.1.14 in CUPS' protected
    # cache. Ignore directories and partial writes.
    if os.path.isdir(old_spool_dir):
        for name in os.listdir(old_spool_dir):
            source = os.path.join(old_spool_dir, name)
            if not os.path.isfile(source) or name.endswith(".part"):
                continue
            target = os.path.join(spool_dir, name)
            if os.path.exists(target):
                root, ext = os.path.splitext(name)
                target = os.path.join(spool_dir, f"{root}-migrated{ext}")
            try:
                os.replace(source, target)
            except OSError:
                continue
            try:
                os.chown(target, owner_uid, owner_gid)
                os.chmod(target, 0o600)
            except OSError:
                pass

    subprocess.run([
        "lpadmin", "-p", "FieldLens-Print", "-E",
        "-v", target_port,
        "-P", ppd_path,
        "-D", "FieldLens Print",
    ], check=True)

    subprocess.run([
        "lpadmin", "-p", "FieldLens-Test-Capture", "-E",
        "-v", "socket://127.0.0.1:9101",
        "-P", ppd_path,
        "-D", "FieldLens Test Capture",
    ], check=True)

    for queue in ("FieldLens-Print", "FieldLens-Test-Capture"):
        subprocess.run(["cupsenable", queue], check=True)
        subprocess.run(["cupsaccept", queue], check=True)
finally:
    try:
        os.unlink(ppd_path)
    except OSError:
        pass
"#;


#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct SystemPrinter {
    pub name: String,
    pub driver: String,
    pub port: String,
    pub address: Option<String>,
    pub is_virtual: bool,
}

#[derive(Debug, Clone, Serialize)]
#[serde(rename_all = "camelCase")]
pub struct VirtualPrinterStatus {
    pub installed: bool,
    pub name: String,
    pub detail: String,
}

fn is_virtual_printer_name(name: &str) -> bool {
    if name.eq_ignore_ascii_case(VIRTUAL_PRINTER_NAME)
        || name.eq_ignore_ascii_case("FieldLens-Print")
    {
        return true;
    }

    #[cfg(target_os = "linux")]
    {
        return name.eq_ignore_ascii_case(TEST_VIRTUAL_PRINTER_NAME)
            || name.eq_ignore_ascii_case(TEST_VIRTUAL_PRINTER_QUEUE);
    }

    #[cfg(not(target_os = "linux"))]
    false
}

pub fn list_system_printers() -> Result<Vec<SystemPrinter>> {
    #[cfg(target_os = "windows")]
    {
        return list_windows_printers();
    }

    #[cfg(target_os = "linux")]
    {
        return list_linux_printers();
    }

    #[allow(unreachable_code)]
    Ok(Vec::new())
}

pub fn virtual_printer_status() -> Result<VirtualPrinterStatus> {
    #[cfg(target_os = "linux")]
    {
        return linux_virtual_printer_status();
    }

    let installed = list_system_printers()?
        .iter()
        .any(|printer| is_virtual_printer_name(&printer.name));

    Ok(VirtualPrinterStatus {
        installed,
        name: VIRTUAL_PRINTER_NAME.into(),
        detail: if installed {
            "Ready in the system print dialog. Keep RAW capture running while printing.".into()
        } else {
            "Not installed yet. Choose the physical destination printer, then create it.".into()
        },
    })
}

pub fn install_virtual_printer(target_printer: &str) -> Result<VirtualPrinterStatus> {
    let target_printer = target_printer.trim();
    if target_printer.is_empty() {
        return Err(anyhow!("choose the physical printer to forward to first"));
    }
    if is_virtual_printer_name(target_printer) {
        return Err(anyhow!("FieldLens Print cannot forward to itself"));
    }

    #[cfg(target_os = "windows")]
    install_windows_virtual_printer(target_printer)?;

    #[cfg(target_os = "linux")]
    install_linux_virtual_printer(target_printer)?;

    virtual_printer_status()
}

pub fn remove_virtual_printer() -> Result<VirtualPrinterStatus> {
    #[cfg(target_os = "windows")]
    remove_windows_virtual_printer()?;

    #[cfg(target_os = "linux")]
    remove_linux_virtual_printer()?;

    virtual_printer_status()
}

#[cfg(target_os = "windows")]
fn list_windows_printers() -> Result<Vec<SystemPrinter>> {
    let script = r#"
$items = @(
  Get-Printer | ForEach-Object {
    $printer = $_
    $port = Get-PrinterPort -Name $printer.PortName -ErrorAction SilentlyContinue
    $address = $null
    if ($null -ne $port -and $port.PrinterHostAddress) {
      $number = if ($port.PortNumber) { $port.PortNumber } else { 9100 }
      $address = "$($port.PrinterHostAddress):$number"
    }
    [pscustomobject]@{
      name = $printer.Name
      driver = $printer.DriverName
      port = $printer.PortName
      address = $address
      isVirtual = ($printer.Name -eq 'FieldLens Print')
    }
  }
)
$items | ConvertTo-Json -Compress
"#;

    let output = hidden_windows_command("powershell.exe")
        .args(["-NoProfile", "-NonInteractive", "-WindowStyle", "Hidden", "-Command", script])
        .output()
        .context("query Windows printers")?;

    if !output.status.success() {
        return Err(anyhow!(
            "Windows printer query failed: {}",
            String::from_utf8_lossy(&output.stderr).trim()
        ));
    }

    let stdout = String::from_utf8_lossy(&output.stdout);
    let value: Value = serde_json::from_str(stdout.trim()).context("decode Windows printer list")?;
    let values = match value {
        Value::Array(values) => values,
        Value::Null => vec![],
        value => vec![value],
    };

    let mut printers = Vec::new();
    for value in values {
        let printer: SystemPrinter = serde_json::from_value(value)?;
        printers.push(printer);
    }
    printers.sort_by(|a, b| a.name.to_lowercase().cmp(&b.name.to_lowercase()));
    Ok(printers)
}

#[cfg(target_os = "windows")]
fn install_windows_virtual_printer(target_printer: &str) -> Result<()> {
    let target = ps_quote(target_printer);
    let script_path = std::env::temp_dir().join(format!(
        "fieldlens-printer-setup-{}.ps1",
        uuid::Uuid::new_v4()
    ));

    let script = format!(
        r#"param([string]$TargetPrinter)
$ErrorActionPreference = 'Stop'
$target = Get-Printer -Name $TargetPrinter -ErrorAction Stop
$portName = '{port}'
$queueName = '{queue}'

if (-not (Get-PrinterPort -Name $portName -ErrorAction SilentlyContinue)) {{
  Add-PrinterPort -Name $portName -PrinterHostAddress '127.0.0.1' -PortNumber 9100
}}

$targetConfig = Get-PrintConfiguration -PrinterName $TargetPrinter -ErrorAction SilentlyContinue
$existing = Get-Printer -Name $queueName -ErrorAction SilentlyContinue
if ($existing) {{
  Set-Printer -Name $queueName -DriverName $target.DriverName -PortName $portName
}} else {{
  Add-Printer -Name $queueName -DriverName $target.DriverName -PortName $portName
}}

# The virtual queue uses the same driver as the physical destination, so its
# PrintTicket can be copied safely. This keeps paper size, duplex settings and
# especially orientation aligned with the real printer instead of falling back
# to the driver's portrait default.
if ($null -ne $targetConfig -and $targetConfig.PrintTicketXML) {{
  Set-PrintConfiguration -PrinterName $queueName -PrintTicketXml $targetConfig.PrintTicketXML
}}
"#,
        port = WINDOWS_PORT_NAME,
        queue = VIRTUAL_PRINTER_NAME,
    );

    fs::write(&script_path, script).context("write Windows printer setup script")?;

    // First run the script directly. This is the reliable path when FieldLens
    // itself was started as administrator and avoids a second hidden RunAs
    // process plus fragile nested PowerShell argument quoting.
    let direct = hidden_windows_command("powershell.exe")
        .args([
            "-NoProfile",
            "-NonInteractive",
            "-ExecutionPolicy",
            "Bypass",
            "-File",
        ])
        .arg(&script_path)
        .args(["-TargetPrinter", target_printer])
        .output()
        .context("run Windows printer setup")?;

    if direct.status.success() {
        let _ = fs::remove_file(&script_path);
        return Ok(());
    }

    // If the app is not elevated, retry through UAC. Keep this as a fallback
    // rather than the primary path so admin-launched builds never depend on a
    // nested hidden RunAs process.
    let path = ps_quote(&script_path.to_string_lossy());
    let elevated = format!(
        "$p = Start-Process -FilePath powershell.exe -Verb RunAs -Wait -PassThru -ArgumentList @('-NoProfile','-NonInteractive','-ExecutionPolicy','Bypass','-File','{path}','-TargetPrinter','{target}'); exit $p.ExitCode"
    );

    let elevated_status = hidden_windows_command("powershell.exe")
        .args(["-NoProfile", "-NonInteractive", "-Command", &elevated])
        .status()
        .context("launch elevated Windows printer setup")?;

    let _ = fs::remove_file(&script_path);

    if !elevated_status.success() {
        let stderr = String::from_utf8_lossy(&direct.stderr).trim().to_string();
        return Err(anyhow!(
            "Windows printer setup failed{}",
            if stderr.is_empty() {
                "; administrator approval may be required".to_string()
            } else {
                format!(": {stderr}")
            }
        ));
    }

    Ok(())
}

#[cfg(target_os = "windows")]
fn remove_windows_virtual_printer() -> Result<()> {
    let script = format!(
        r#"$ErrorActionPreference = 'Stop'
$queueName = '{queue}'
$portName = '{port}'
if (Get-Printer -Name $queueName -ErrorAction SilentlyContinue) {{
  Remove-Printer -Name $queueName
}}
if (Get-PrinterPort -Name $portName -ErrorAction SilentlyContinue) {{
  Remove-PrinterPort -Name $portName
}}
"#,
        queue = VIRTUAL_PRINTER_NAME,
        port = WINDOWS_PORT_NAME,
    );

    let script_path = std::env::temp_dir().join(format!(
        "fieldlens-printer-remove-{}.ps1",
        uuid::Uuid::new_v4()
    ));
    fs::write(&script_path, script)?;
    let direct = hidden_windows_command("powershell.exe")
        .args([
            "-NoProfile",
            "-NonInteractive",
            "-ExecutionPolicy",
            "Bypass",
            "-File",
        ])
        .arg(&script_path)
        .output()
        .context("run Windows printer removal")?;

    if direct.status.success() {
        let _ = fs::remove_file(&script_path);
        return Ok(());
    }

    let path = ps_quote(&script_path.to_string_lossy());
    let elevated = format!(
        "$p = Start-Process -FilePath powershell.exe -Verb RunAs -Wait -PassThru -ArgumentList @('-NoProfile','-NonInteractive','-ExecutionPolicy','Bypass','-File','{path}'); exit $p.ExitCode"
    );
    let status = hidden_windows_command("powershell.exe")
        .args(["-NoProfile", "-NonInteractive", "-Command", &elevated])
        .status()?;
    let _ = fs::remove_file(&script_path);

    if !status.success() {
        let stderr = String::from_utf8_lossy(&direct.stderr).trim().to_owned();
        return Err(anyhow!(
            "removing FieldLens Print failed{}",
            if stderr.is_empty() {
                String::new()
            } else {
                format!(": {stderr}")
            }
        ));
    }
    Ok(())
}

#[cfg(target_os = "windows")]
fn ps_quote(value: &str) -> String {
    value.replace('\'', "''")
}

#[cfg(target_os = "linux")]
fn list_linux_printers() -> Result<Vec<SystemPrinter>> {
    let output = match Command::new("lpstat").arg("-v").output() {
        Ok(output) => output,
        Err(error) if error.kind() == std::io::ErrorKind::NotFound => {
            return Err(anyhow!(
                "CUPS client tools are missing. Install the cups-client package, then reopen FieldLens Print."
            ))
        }
        Err(error) => return Err(error).context("query CUPS printers with lpstat"),
    };

    if !output.status.success() {
        return Err(anyhow!(
            "CUPS printer query failed: {}",
            String::from_utf8_lossy(&output.stderr).trim()
        ));
    }

    let mut printers = Vec::new();
    for line in String::from_utf8_lossy(&output.stdout).lines() {
        let Some(rest) = line.strip_prefix("device for ") else {
            continue;
        };
        let Some((name, uri)) = rest.split_once(": ") else {
            continue;
        };
        // Ignore placeholder/dummy queues. They can expose a PPD but are not a
        // usable physical destination and can make Chromium reject the cloned
        // FieldLens queue as "not installed correctly".
        if uri == "///dev/null" || uri == "file:///dev/null" {
            continue;
        }

        let address = socket_uri_to_address(uri);
        printers.push(SystemPrinter {
            name: name.to_string(),
            driver: String::new(),
            port: uri.to_string(),
            address,
            is_virtual: is_virtual_printer_name(name),
        });
    }
    printers.sort_by(|a, b| a.name.to_lowercase().cmp(&b.name.to_lowercase()));
    Ok(printers)
}

#[cfg(target_os = "linux")]
fn socket_uri_to_address(uri: &str) -> Option<String> {
    let value = uri.strip_prefix("socket://")?;
    let authority = value.split('/').next().unwrap_or(value);
    if authority.contains(':') {
        Some(authority.to_string())
    } else if authority.is_empty() {
        None
    } else {
        Some(format!("{authority}:9100"))
    }
}

#[cfg(target_os = "linux")]
fn linux_queue_ready(queue: &str) -> Result<bool> {
    let state = Command::new("lpstat")
        .args(["-p", queue])
        .output()
        .with_context(|| format!("query {queue} CUPS state"))?;
    let accepting = Command::new("lpstat")
        .args(["-a", queue])
        .output()
        .with_context(|| format!("query {queue} accepting state"))?;

    let state_text = String::from_utf8_lossy(&state.stdout);
    let accepting_text = String::from_utf8_lossy(&accepting.stdout);
    Ok(
        state.status.success()
            && !state_text.to_ascii_lowercase().contains("disabled")
            && accepting.status.success()
            && accepting_text.to_ascii_lowercase().contains("accepting requests"),
    )
}

#[cfg(target_os = "linux")]
fn linux_capture_filter_health() -> Result<()> {
    let filter_path = cups_filter_dir()?.join("fieldlens-capture");
    let metadata = fs::metadata(&filter_path)
        .with_context(|| format!("FieldLens CUPS filter missing at {}", filter_path.display()))?;
    if !metadata.is_file() {
        return Err(anyhow!("FieldLens CUPS filter is not a regular file"));
    }

    let check = Command::new("python3")
        .arg("-c")
        .arg("import pathlib,sys; p=sys.argv[1]; compile(pathlib.Path(p).read_text(), p, 'exec')")
        .arg(&filter_path)
        .output()
        .context("validate FieldLens CUPS filter with python3")?;
    if !check.status.success() {
        return Err(anyhow!(
            "FieldLens CUPS filter is invalid: {}",
            String::from_utf8_lossy(&check.stderr).trim()
        ));
    }
    Ok(())
}

#[cfg(target_os = "linux")]
fn linux_virtual_printer_status() -> Result<VirtualPrinterStatus> {
    let printers = list_linux_printers()?;
    let print_installed = printers
        .iter()
        .any(|printer| printer.name.eq_ignore_ascii_case("FieldLens-Print"));
    let test_installed = printers
        .iter()
        .any(|printer| printer.name.eq_ignore_ascii_case(TEST_VIRTUAL_PRINTER_QUEUE));

    if !print_installed || !test_installed {
        return Ok(VirtualPrinterStatus {
            installed: false,
            name: VIRTUAL_PRINTER_NAME.into(),
            detail: "FieldLens CUPS queues are incomplete. Click Create / repair printers.".into(),
        });
    }

    let print_ready = linux_queue_ready("FieldLens-Print")?;
    let test_ready = linux_queue_ready(TEST_VIRTUAL_PRINTER_QUEUE)?;
    if !print_ready || !test_ready {
        return Ok(VirtualPrinterStatus {
            installed: false,
            name: VIRTUAL_PRINTER_NAME.into(),
            detail: "A FieldLens CUPS queue is disabled or not accepting jobs. Click Create / repair printers.".into(),
        });
    }

    if let Err(error) = linux_capture_filter_health() {
        return Ok(VirtualPrinterStatus {
            installed: false,
            name: VIRTUAL_PRINTER_NAME.into(),
            detail: format!("Capture filter is broken: {error}. Click Create / repair printers."),
        });
    }

    Ok(VirtualPrinterStatus {
        installed: true,
        name: VIRTUAL_PRINTER_NAME.into(),
        detail: "Ready. Original documents are captured by the CUPS pre-filter before normal CUPS rendering; test jobs use the same capture path with rendered output discarded.".into(),
    })
}

#[cfg(target_os = "linux")]
fn run_cups_repair_command(program: &str, args: &[&str]) -> Result<()> {
    let direct = Command::new(program).args(args).status();
    if matches!(direct, Ok(status) if status.success()) {
        return Ok(());
    }

    let status = Command::new("pkexec")
        .arg(program)
        .args(args)
        .status()
        .with_context(|| format!("run elevated {program}"))?;
    if !status.success() {
        return Err(anyhow!("{program} failed; administrator approval may be required"));
    }
    Ok(())
}

#[cfg(target_os = "linux")]
fn cups_filter_dir() -> Result<&'static Path> {
    for candidate in ["/usr/lib/cups/filter", "/usr/libexec/cups/filter"] {
        let path = Path::new(candidate);
        if path.is_dir() {
            return Ok(path);
        }
    }
    Err(anyhow!("CUPS filter directory was not found"))
}

#[cfg(target_os = "linux")]
fn run_linux_admin(program: &str, args: &[String], context: &str) -> Result<()> {
    let direct = Command::new(program).args(args).status();
    if matches!(direct, Ok(status) if status.success()) {
        return Ok(());
    }

    let status = Command::new("pkexec")
        .arg(program)
        .args(args)
        .status()
        .with_context(|| format!("run elevated {context}"))?;
    if !status.success() {
        return Err(anyhow!("{context} failed; administrator approval may be required"));
    }
    Ok(())
}

#[cfg(target_os = "linux")]
fn install_linux_capture_filter() -> Result<()> {
    let filter_dir = cups_filter_dir()?;
    let filter_path = filter_dir.join("fieldlens-capture");
    let temp_filter = std::env::temp_dir().join(format!(
        "fieldlens-capture-{}.py",
        uuid::Uuid::new_v4()
    ));
    fs::write(&temp_filter, FIELDLENS_CUPS_FILTER).context("write FieldLens CUPS pre-filter")?;

    let install_filter_args = vec![
        "-m".to_string(),
        "0755".to_string(),
        temp_filter.to_string_lossy().into_owned(),
        filter_path.to_string_lossy().into_owned(),
    ];
    let filter_result = run_linux_admin(
        "install",
        &install_filter_args,
        "install FieldLens CUPS pre-filter",
    );
    let _ = fs::remove_file(&temp_filter);
    filter_result?;

    let spool_args = vec![
        "-d".to_string(),
        "-m".to_string(),
        "0777".to_string(),
        FIELDLENS_CUPS_SPOOL_DIR.to_string(),
    ];
    run_linux_admin("install", &spool_args, "create FieldLens CUPS capture spool")?;
    Ok(())
}

#[cfg(target_os = "linux")]
fn build_fieldlens_ppd(target_printer: &str) -> Result<PathBuf> {
    let source = PathBuf::from("/etc/cups/ppd").join(format!("{target_printer}.ppd"));
    if !source.exists() {
        return Err(anyhow!(
            "CUPS PPD for '{target_printer}' was not found; FieldLens needs the installed printer definition to preserve browser print capabilities"
        ));
    }

    let original = match fs::read_to_string(&source) {
        Ok(contents) => contents,
        Err(direct_error) => {
            // CUPS commonly stores PPDs as root:lp 0640. Desktop users can
            // enumerate the queue but cannot necessarily read its PPD.
            // Reuse the existing PolicyKit setup flow for a read-only fallback.
            let output = Command::new("pkexec")
                .arg("cat")
                .arg(&source)
                .output()
                .with_context(|| {
                    format!(
                        "read target printer PPD {} (direct read failed: {direct_error})",
                        source.display()
                    )
                })?;

            if !output.status.success() {
                return Err(anyhow!(
                    "could not read target printer PPD {}: {}",
                    source.display(),
                    String::from_utf8_lossy(&output.stderr).trim()
                ));
            }

            String::from_utf8(output.stdout)
                .with_context(|| format!("decode target printer PPD {}", source.display()))?
        }
    };
    let mut cleaned = original
        .lines()
        .filter(|line| !line.contains("fieldlens-capture"))
        .collect::<Vec<_>>()
        .join("\n");
    cleaned.push('\n');

    let prefilter = concat!(
        "*% FieldLens original-document capture before cups-filters universal conversion\n",
        "*cupsPreFilter: \"application/vnd.universal-input 0 fieldlens-capture\"\n"
    );
    if let Some(index) = cleaned.rfind("*% End") {
        cleaned.insert_str(index, prefilter);
    } else {
        cleaned.push_str(prefilter);
    }

    let target = std::env::temp_dir().join(format!(
        "fieldlens-{}.ppd",
        uuid::Uuid::new_v4()
    ));
    fs::write(&target, cleaned).context("write FieldLens derived PPD")?;
    Ok(target)
}

#[cfg(target_os = "linux")]
fn install_linux_virtual_printer(target_printer: &str) -> Result<()> {
    let printers = list_linux_printers()?;
    let target = printers
        .iter()
        .find(|printer| printer.name == target_printer && !printer.is_virtual)
        .ok_or_else(|| anyhow!(
            "selected printer '{target_printer}' is not installed or available in CUPS"
        ))?;

    let filter_dir = cups_filter_dir()?;
    let filter_path = filter_dir.join("fieldlens-capture");

    let temp_filter = std::env::temp_dir().join(format!(
        "fieldlens-capture-{}.py",
        uuid::Uuid::new_v4()
    ));
    let temp_helper = std::env::temp_dir().join(format!(
        "fieldlens-cups-repair-{}.py",
        uuid::Uuid::new_v4()
    ));

    let uid = Command::new("id")
        .arg("-u")
        .output()
        .context("read current Linux user id")?;
    let gid = Command::new("id")
        .arg("-g")
        .output()
        .context("read current Linux group id")?;
    if !uid.status.success() || !gid.status.success() {
        return Err(anyhow!("could not determine the current Linux user for capture ownership"));
    }
    let uid = String::from_utf8_lossy(&uid.stdout).trim().to_string();
    let gid = String::from_utf8_lossy(&gid.stdout).trim().to_string();

    let filter_script = render_linux_capture_filter(&uid, &gid);
    fs::write(&temp_filter, filter_script)
        .context("write FieldLens CUPS capture filter")?;
    fs::write(&temp_helper, FIELDLENS_CUPS_REPAIR_HELPER)
        .context("write FieldLens CUPS repair helper")?;

    let status = Command::new("pkexec")
        .arg("python3")
        .arg(&temp_helper)
        .arg(target_printer)
        .arg(&target.port)
        .arg(&temp_filter)
        .arg(&filter_path)
        .arg(&uid)
        .arg(&gid)
        .status()
        .context("run elevated FieldLens CUPS repair")?;

    let _ = fs::remove_file(&temp_filter);
    let _ = fs::remove_file(&temp_helper);

    if !status.success() {
        return Err(anyhow!(
            "FieldLens printer repair failed; administrator approval may be required"
        ));
    }

    Ok(())
}

#[cfg(target_os = "linux")]
fn remove_linux_virtual_printer() -> Result<()> {
    for queue in ["FieldLens-Print", TEST_VIRTUAL_PRINTER_QUEUE] {
        let args = vec!["-x".to_string(), queue.to_string()];
        let direct = Command::new("lpadmin").args(&args).status();
        if matches!(direct, Ok(status) if status.success()) {
            continue;
        }

        let status = Command::new("pkexec")
            .arg("lpadmin")
            .args(&args)
            .status()
            .context("run elevated CUPS printer removal")?;
        if !status.success() {
            return Err(anyhow!("removing FieldLens CUPS printer '{queue}' failed"));
        }
    }
    Ok(())
}


#[cfg(all(test, target_os = "linux"))]
mod linux_filter_tests {
    use super::*;

    #[test]
    fn rendered_cups_filter_compiles_with_python() {
        let path = std::env::temp_dir().join(format!(
            "fieldlens-filter-test-{}.py",
            uuid::Uuid::new_v4()
        ));
        let script = render_linux_capture_filter("1000", "1000");
        fs::write(&path, script).expect("write rendered CUPS filter");

        let output = Command::new("python3")
            .args(["-m", "py_compile"])
            .arg(&path)
            .output()
            .expect("run python3 -m py_compile");

        let _ = fs::remove_file(&path);
        assert!(
            output.status.success(),
            "rendered CUPS filter must compile: {}",
            String::from_utf8_lossy(&output.stderr)
        );
    }
}