//! Authenticated local IPC for the Windows sandbox provisioning service.
//! Configuration parse failures and unsupported home drives defer provisioning to
//! the client's elevated helper.
//! Shutdown wakeups are retried until the listener connects or stops.

mod authentication;
mod home;
mod request;

use anyhow::Context;
use anyhow::Result;
use anyhow::bail;
use authentication::authenticate_client;
use codex_windows_sandbox::FramedProvisioningMessage;
use codex_windows_sandbox::PROVISIONING_PROTOCOL_VERSION;
use codex_windows_sandbox::ProvisioningMessage;
use codex_windows_sandbox::SandboxProvisioningResponse;
use codex_windows_sandbox::ensure_sandbox_users_group;
use codex_windows_sandbox::run_elevated_provisioning_setup_with_retained_handles;
use codex_windows_sandbox::sandbox_setup_is_complete_with_settings;
use codex_windows_sandbox::string_from_sid_bytes;
use codex_windows_sandbox::to_wide;
use codex_windows_sandbox::write_provisioning_frame;
use home::OwnedHandle;
#[cfg(test)]
use home::pin_existing_ancestors;
#[cfg(test)]
use request::ProvisioningRequest;
use request::validate_request;
use std::mem::size_of;
use std::os::windows::fs::MetadataExt;
use std::os::windows::io::BorrowedHandle;
use std::ptr;
use std::sync::Arc;
use std::sync::atomic::AtomicBool;
use std::sync::atomic::Ordering;
use std::time::Duration;
use std::time::Instant;
use windows_sys::Win32::Foundation as foundation;
use windows_sys::Win32::Foundation::HANDLE;
use windows_sys::Win32::Security as security;
use windows_sys::Win32::Security::Authorization as authorization;
use windows_sys::Win32::Storage::FileSystem as filesystem;
use windows_sys::Win32::System::Pipes as pipes;

pub(crate) const PIPE_NAME: &str = codex_windows_sandbox::SANDBOX_PROVISIONING_PIPE_NAME;

const MAX_REQUEST_BYTES: usize = 4096;
const MAX_RESPONSE_MESSAGE_BYTES: usize = 512;
const REQUEST_IDLE_TIMEOUT: Duration = Duration::from_secs(5);
const PIPE_USER_ACCESS: &str = "0x0012019b";

struct SecurityDescriptor(security::PSECURITY_DESCRIPTOR);

impl Drop for SecurityDescriptor {
    fn drop(&mut self) {
        unsafe { foundation::LocalFree(self.0 as foundation::HLOCAL) };
    }
}

#[derive(Debug, Eq, PartialEq)]
enum PipeConnection {
    Connected,
    Disconnected,
}

pub(crate) fn run(shutdown: Arc<AtomicBool>, on_ready: impl FnOnce() -> Result<()>) -> Result<()> {
    let sandbox_sid = ensure_sandbox_users_group()?;
    let sid_string = string_from_sid_bytes(&sandbox_sid).map_err(anyhow::Error::msg)?;
    let sddl = pipe_security_descriptor(&sid_string);
    let mut descriptor: security::PSECURITY_DESCRIPTOR = ptr::null_mut();
    if unsafe {
        authorization::ConvertStringSecurityDescriptorToSecurityDescriptorW(
            to_wide(sddl).as_ptr(),
            authorization::SDDL_REVISION_1,
            &mut descriptor,
            ptr::null_mut(),
        )
    } == 0
    {
        return Err(std::io::Error::last_os_error()).context("create provisioning pipe DACL");
    }
    let descriptor = SecurityDescriptor(descriptor);
    let attributes = security::SECURITY_ATTRIBUTES {
        nLength: size_of::<security::SECURITY_ATTRIBUTES>() as u32,
        lpSecurityDescriptor: descriptor.0,
        bInheritHandle: 0,
    };

    let pipe = unsafe {
        pipes::CreateNamedPipeW(
            to_wide(PIPE_NAME).as_ptr(),
            filesystem::PIPE_ACCESS_DUPLEX | filesystem::FILE_FLAG_FIRST_PIPE_INSTANCE,
            pipes::PIPE_TYPE_BYTE
                | pipes::PIPE_READMODE_BYTE
                | pipes::PIPE_WAIT
                | pipes::PIPE_REJECT_REMOTE_CLIENTS,
            1,
            1024,
            MAX_REQUEST_BYTES as u32,
            0,
            &attributes,
        )
    };
    if pipe == foundation::INVALID_HANDLE_VALUE {
        return Err(std::io::Error::last_os_error()).context("create provisioning pipe");
    }
    let pipe = OwnedHandle(pipe);
    on_ready().context("publish provisioning listener readiness")?;

    while !shutdown.load(Ordering::Acquire) {
        if accept_pipe_connection(pipe.0)? == PipeConnection::Disconnected {
            continue;
        }
        if shutdown.load(Ordering::Acquire) {
            break;
        }

        let authorized_process = match crate::package_identity::authorize_client_process(pipe.0) {
            Ok(process) => process,
            Err(_) => {
                unsafe { pipes::DisconnectNamedPipe(pipe.0) };
                continue;
            }
        };
        let result = handle_request(pipe.0, &authorized_process, &sandbox_sid, &shutdown);
        let response = match result {
            Ok(response) => response,
            Err(error) if error.is::<home::UnsupportedHomeDrive>() => {
                SandboxProvisioningResponse::Unavailable
            }
            Err(error) => {
                eprintln!("sandbox provisioning request failed: {error}");
                let mut message = String::new();
                for character in error.to_string().chars() {
                    let character = if character.is_control() {
                        ' '
                    } else {
                        character
                    };
                    if message.len() + character.len_utf8() > MAX_RESPONSE_MESSAGE_BYTES {
                        break;
                    }
                    message.push(character);
                }
                SandboxProvisioningResponse::Error { message }
            }
        };
        let response = FramedProvisioningMessage {
            version: PROVISIONING_PROTOCOL_VERSION,
            message: ProvisioningMessage::ProvisionSandboxResponse { payload: response },
        };
        let mut frame = Vec::new();
        write_provisioning_frame(&mut frame, &response)
            .context("serialize sandbox provisioning response")?;
        let mut written = 0;
        let sent = unsafe {
            filesystem::WriteFile(
                pipe.0,
                frame.as_ptr(),
                frame.len() as u32,
                &mut written,
                ptr::null_mut(),
            )
        };
        if sent != 0 {
            let deadline = Instant::now() + Duration::from_secs(1);
            while !shutdown.load(Ordering::Acquire) && Instant::now() < deadline {
                if unsafe {
                    pipes::PeekNamedPipe(
                        pipe.0,
                        ptr::null_mut(),
                        0,
                        ptr::null_mut(),
                        ptr::null_mut(),
                        ptr::null_mut(),
                    )
                } == 0
                {
                    break;
                }
                std::thread::sleep(Duration::from_millis(10));
            }
        }
        unsafe { pipes::DisconnectNamedPipe(pipe.0) };
    }
    Ok(())
}

fn accept_pipe_connection(pipe: HANDLE) -> Result<PipeConnection> {
    if unsafe { pipes::ConnectNamedPipe(pipe, ptr::null_mut()) } != 0 {
        return Ok(PipeConnection::Connected);
    }

    let error = unsafe { foundation::GetLastError() };
    match error {
        foundation::ERROR_PIPE_CONNECTED => Ok(PipeConnection::Connected),
        foundation::ERROR_NO_DATA | foundation::ERROR_BROKEN_PIPE => {
            if unsafe { pipes::DisconnectNamedPipe(pipe) } == 0 {
                let reset_error = std::io::Error::last_os_error();
                if reset_error.raw_os_error() != Some(foundation::ERROR_PIPE_NOT_CONNECTED as i32) {
                    return Err(reset_error).context("reset disconnected provisioning client");
                }
            }
            Ok(PipeConnection::Disconnected)
        }
        _ => Err(std::io::Error::from_raw_os_error(error as i32))
            .context("accept provisioning client"),
    }
}

pub(crate) fn wake(pipe_name: &str, is_stopped: impl Fn() -> bool) {
    let pipe_name = to_wide(pipe_name);
    while !is_stopped() {
        let handle = unsafe {
            filesystem::CreateFileW(
                pipe_name.as_ptr(),
                foundation::GENERIC_WRITE,
                /*dwsharemode*/ 0,
                ptr::null(),
                filesystem::OPEN_EXISTING,
                /*dwflagsandattributes*/ 0,
                /*htemplatefile*/ 0,
            )
        };
        if handle != foundation::INVALID_HANDLE_VALUE {
            unsafe { foundation::CloseHandle(handle) };
            return;
        }
        // A disconnected instance cannot accept the wakeup until ConnectNamedPipe runs.
        std::thread::sleep(Duration::from_millis(25));
    }
}

fn pipe_security_descriptor(sandbox_sid: &str) -> String {
    format!("D:P(D;;GA;;;{sandbox_sid})(A;;GA;;;SY)(A;;GA;;;BA)(A;;{PIPE_USER_ACCESS};;;IU)")
}

fn handle_request(
    pipe: HANDLE,
    authorized_process: &crate::package_identity::AuthorizedClientProcess,
    sandbox_sid: &[u8],
    shutdown: &AtomicBool,
) -> Result<SandboxProvisioningResponse> {
    let deadline = Instant::now() + REQUEST_IDLE_TIMEOUT;
    let mut request = [0_u8; MAX_REQUEST_BYTES];
    let mut request_length = 0;
    loop {
        if shutdown.load(Ordering::Acquire) {
            bail!("service is stopping");
        }
        if Instant::now() >= deadline {
            bail!("provisioning request timed out");
        }
        let mut available = 0;
        if unsafe {
            pipes::PeekNamedPipe(
                pipe,
                ptr::null_mut(),
                0,
                ptr::null_mut(),
                &mut available,
                ptr::null_mut(),
            )
        } == 0
        {
            return Err(std::io::Error::last_os_error()).context("inspect provisioning request");
        }
        if available as usize > MAX_REQUEST_BYTES - request_length {
            bail!("provisioning request exceeds size limit");
        }
        if available != 0 {
            let mut read = 0;
            if unsafe {
                filesystem::ReadFile(
                    pipe,
                    request[request_length..].as_mut_ptr(),
                    available,
                    &mut read,
                    ptr::null_mut(),
                )
            } == 0
            {
                return Err(std::io::Error::last_os_error()).context("read provisioning request");
            }
            if read == 0 {
                bail!("provisioning client sent an empty request");
            }
            request_length += read as usize;
            let received = &request[..request_length];
            if received.len() >= size_of::<u32>() {
                let payload_length =
                    u32::from_le_bytes([received[0], received[1], received[2], received[3]])
                        as usize;
                if payload_length > MAX_REQUEST_BYTES - size_of::<u32>() {
                    bail!("provisioning request exceeds size limit");
                }
                let frame_length = size_of::<u32>() + payload_length;
                if request_length > frame_length {
                    bail!("provisioning requests must contain exactly one IPC frame");
                }
                if request_length == frame_length {
                    break;
                }
            }
            continue;
        }
        std::thread::sleep(Duration::from_millis(25));
    }

    let request = validate_request(&request[..request_length])?;
    let (identity, policy_result) =
        authenticate_client(pipe, authorized_process, sandbox_sid, &request)?;
    if let Err(error) = policy_result {
        if is_config_parse_error(&error) {
            return Ok(SandboxProvisioningResponse::Unavailable);
        }
        crate::service::log_error(
            crate::service::EVENT_REQUEST_REJECTED,
            &format!("Codex sandbox provisioning was rejected by administrator policy: {error}"),
        );
        return Err(error)
            .context("requested sandbox settings violate administrator-controlled machine policy");
    }
    if sandbox_setup_is_complete_with_settings(&identity.codex_home, &request.settings) {
        return Ok(SandboxProvisioningResponse::Ok);
    }
    let helper = std::env::current_exe()
        .context("locate the provisioning service executable")?
        .with_file_name("codex-windows-sandbox-setup.exe");
    let helper_metadata = helper
        .symlink_metadata()
        .with_context(|| format!("inspect packaged setup helper {}", helper.display()))?;
    if !helper_metadata.is_file()
        || helper_metadata.file_attributes() & filesystem::FILE_ATTRIBUTE_REPARSE_POINT != 0
    {
        bail!(
            "refusing invalid packaged setup helper {}",
            helper.display()
        );
    }
    let retained_handles = identity
        .directory_handles
        .iter()
        // The identity owns these handles through the synchronous helper launch and wait.
        .map(|handle| unsafe { BorrowedHandle::borrow_raw(handle.0 as _) })
        .collect::<Vec<_>>();
    match run_elevated_provisioning_setup_with_retained_handles(
        &identity.codex_home,
        &identity.account,
        request.settings,
        &retained_handles,
    ) {
        Ok(()) => {
            crate::service::log_information(
                crate::service::EVENT_PROVISIONING_SUCCEEDED,
                "Codex sandbox provisioning completed successfully.",
            );
            Ok(SandboxProvisioningResponse::Ok)
        }
        Err(error) => {
            crate::service::log_error(
                crate::service::EVENT_PROVISIONING_FAILED,
                &format!("Codex sandbox provisioning failed: {error}"),
            );
            Err(error).context("sandbox provisioning failed")
        }
    }
}

fn is_config_parse_error(error: &anyhow::Error) -> bool {
    error.chain().any(|cause| {
        cause.is::<toml::de::Error>()
            || cause
                .downcast_ref::<std::io::Error>()
                .and_then(std::io::Error::get_ref)
                .is_some_and(<dyn std::error::Error + Send + Sync>::is::<toml::de::Error>)
    })
}

#[cfg(test)]
#[path = "ipc_tests.rs"]
mod tests;