use crate::regular_file;
use std::ffi::OsStr;
use std::ffi::c_void;
use std::io;
use std::io::Write;
use std::mem::size_of;
use std::os::windows::ffi::OsStrExt;
use std::os::windows::io::AsRawHandle;
use std::os::windows::io::FromRawHandle;
use std::os::windows::io::OwnedHandle;
use std::os::windows::io::RawHandle;
use std::path::Component;
use std::path::Path;
use std::path::PathBuf;
use std::path::Prefix;
use std::ptr;
use windows_sys::Win32::Foundation::HANDLE;
use windows_sys::Win32::Foundation::INVALID_HANDLE_VALUE;
use windows_sys::Win32::Foundation::NTSTATUS;
use windows_sys::Win32::Foundation::RtlNtStatusToDosError;
use windows_sys::Win32::Foundation::UNICODE_STRING;
use windows_sys::Win32::Security::SECURITY_QUALITY_OF_SERVICE;
use windows_sys::Win32::Security::SecurityIdentification;
use windows_sys::Win32::Storage::FileSystem::DELETE;
use windows_sys::Win32::Storage::FileSystem::FILE_ATTRIBUTE_NORMAL;
use windows_sys::Win32::Storage::FileSystem::FILE_DISPOSITION_INFO;
use windows_sys::Win32::Storage::FileSystem::FILE_GENERIC_READ;
use windows_sys::Win32::Storage::FileSystem::FILE_READ_ATTRIBUTES;
use windows_sys::Win32::Storage::FileSystem::FILE_SHARE_DELETE;
use windows_sys::Win32::Storage::FileSystem::FILE_SHARE_READ;
use windows_sys::Win32::Storage::FileSystem::FILE_SHARE_WRITE;
use windows_sys::Win32::Storage::FileSystem::FILE_WRITE_DATA;
use windows_sys::Win32::Storage::FileSystem::FileDispositionInfo;
use windows_sys::Win32::Storage::FileSystem::SetFileInformationByHandle;
use windows_sys::Win32::System::IO::IO_STATUS_BLOCK;
use windows_sys::Win32::System::IO::IO_STATUS_BLOCK_0;
use windows_sys::Win32::System::Kernel::OBJ_CASE_INSENSITIVE;
use windows_sys::Win32::System::Kernel::OBJ_DONT_REPARSE;

const FILE_DIRECTORY_FILE: u32 = 0x0000_0001;
const FILE_SYNCHRONOUS_IO_NONALERT: u32 = 0x0000_0020;
const FILE_NON_DIRECTORY_FILE: u32 = 0x0000_0040;
const FILE_OPEN: u32 = 1;
const FILE_CREATE: u32 = 2;
const FILE_OPEN_IF: u32 = 3;
const SYNCHRONIZE_ACCESS: u32 = 0x0010_0000;
const STATUS_REPARSE_POINT_ENCOUNTERED: NTSTATUS = 0xC000_050B_u32 as i32;
const SECURITY_STATIC_TRACKING: u8 = 0;
const BOOLEAN_TRUE: u8 = 1;

#[repr(C)]
struct ObjectAttributes {
    length: u32,
    root_directory: HANDLE,
    object_name: *const UNICODE_STRING,
    attributes: u32,
    security_descriptor: *const c_void,
    security_quality_of_service: *const c_void,
}

#[link(name = "ntdll")]
unsafe extern "system" {
    fn NtCreateFile(
        file_handle: *mut HANDLE,
        desired_access: u32,
        object_attributes: *const ObjectAttributes,
        io_status_block: *mut IO_STATUS_BLOCK,
        allocation_size: *const i64,
        file_attributes: u32,
        share_access: u32,
        create_disposition: u32,
        create_options: u32,
        ea_buffer: *const c_void,
        ea_length: u32,
    ) -> NTSTATUS;
}

fn nt_path(path: &Path) -> io::Result<Vec<u16>> {
    if !path.is_absolute() {
        return Err(io::Error::new(
            io::ErrorKind::InvalidInput,
            "no-follow filesystem operations require an absolute path",
        ));
    }

    let (prefix, source_offset) = match path.components().next() {
        Some(Component::Prefix(prefix)) => match prefix.kind() {
            Prefix::Disk(_) => ("\\??\\", 0),
            Prefix::VerbatimDisk(_) => ("\\??\\", 4),
            Prefix::UNC(_, _) => ("\\??\\UNC\\", 2),
            Prefix::VerbatimUNC(_, _) => ("\\??\\UNC\\", 8),
            _ => {
                return Err(io::Error::new(
                    io::ErrorKind::InvalidInput,
                    "no-follow filesystem operations require a local disk or UNC path",
                ));
            }
        },
        _ => {
            return Err(io::Error::new(
                io::ErrorKind::InvalidInput,
                "no-follow filesystem operations require an absolute Windows path",
            ));
        }
    };

    let mut result: Vec<u16> = OsStr::new(prefix).encode_wide().collect();
    result.extend(
        path.as_os_str()
            .encode_wide()
            .skip(source_offset)
            .map(|unit| {
                if unit == b'/' as u16 {
                    b'\\' as u16
                } else {
                    unit
                }
            }),
    );
    result.push(0);
    Ok(result)
}

fn open_handle(
    path: &Path,
    desired_access: u32,
    create_disposition: u32,
    create_options: u32,
) -> io::Result<OwnedHandle> {
    let mut path = nt_path(path)?;
    let name_length = u16::try_from((path.len() - 1) * size_of::<u16>())
        .map_err(|_| io::Error::new(io::ErrorKind::InvalidInput, "filesystem path is too long"))?;
    let maximum_length = u16::try_from(path.len() * size_of::<u16>())
        .map_err(|_| io::Error::new(io::ErrorKind::InvalidInput, "filesystem path is too long"))?;
    let object_name = UNICODE_STRING {
        Length: name_length,
        MaximumLength: maximum_length,
        Buffer: path.as_mut_ptr(),
    };
    let security_quality_of_service = SECURITY_QUALITY_OF_SERVICE {
        Length: size_of::<SECURITY_QUALITY_OF_SERVICE>() as u32,
        ImpersonationLevel: SecurityIdentification,
        ContextTrackingMode: SECURITY_STATIC_TRACKING,
        EffectiveOnly: BOOLEAN_TRUE,
    };
    let object_attributes = ObjectAttributes {
        length: size_of::<ObjectAttributes>() as u32,
        root_directory: 0,
        object_name: &object_name,
        attributes: OBJ_CASE_INSENSITIVE as u32 | OBJ_DONT_REPARSE as u32,
        security_descriptor: ptr::null(),
        security_quality_of_service: (&raw const security_quality_of_service).cast(),
    };
    let mut io_status_block = IO_STATUS_BLOCK {
        Anonymous: IO_STATUS_BLOCK_0 { Status: 0 },
        Information: 0,
    };
    let mut handle = 0;
    let status = unsafe {
        NtCreateFile(
            &mut handle,
            desired_access | SYNCHRONIZE_ACCESS,
            &object_attributes,
            &mut io_status_block,
            ptr::null(),
            FILE_ATTRIBUTE_NORMAL,
            FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
            create_disposition,
            create_options | FILE_SYNCHRONOUS_IO_NONALERT,
            ptr::null(),
            /*ea_length*/ 0,
        )
    };
    if status < 0 {
        if status == STATUS_REPARSE_POINT_ENCOUNTERED {
            return Err(io::Error::new(
                io::ErrorKind::InvalidInput,
                "path contains a reparse point",
            ));
        }
        let code = unsafe { RtlNtStatusToDosError(status) };
        return Err(io::Error::from_raw_os_error(code as i32));
    }
    if handle == 0 || handle == INVALID_HANDLE_VALUE {
        return Err(io::Error::other(
            "NtCreateFile returned an invalid filesystem handle",
        ));
    }

    Ok(unsafe { OwnedHandle::from_raw_handle(handle as RawHandle) })
}

fn open_entry(path: &Path) -> io::Result<std::fs::File> {
    let handle = open_handle(
        path,
        FILE_READ_ATTRIBUTES,
        FILE_OPEN,
        /*create_options*/ 0,
    )?;
    Ok(std::fs::File::from(handle))
}

fn open_file_sync(path: &Path) -> io::Result<std::fs::File> {
    let handle = open_handle(path, FILE_GENERIC_READ, FILE_OPEN, FILE_NON_DIRECTORY_FILE)?;
    let file = std::fs::File::from(handle);
    validate_regular_file(&file, path)?;
    Ok(file)
}

fn validate_regular_file(file: &std::fs::File, path: &Path) -> io::Result<()> {
    if !regular_file::is_disk_file(file) || !file.metadata()?.is_file() {
        return Err(io::Error::new(
            io::ErrorKind::InvalidInput,
            format!("path `{}` is not a file", path.display()),
        ));
    }
    Ok(())
}

pub(super) async fn open_file(path: PathBuf) -> io::Result<tokio::fs::File> {
    tokio::task::spawn_blocking(move || open_file_sync(&path).map(tokio::fs::File::from_std))
        .await
        .map_err(|error| io::Error::other(format!("filesystem task failed: {error}")))?
}

pub(super) async fn write_file(path: PathBuf, contents: Vec<u8>) -> io::Result<()> {
    tokio::task::spawn_blocking(move || {
        let handle = open_handle(
            &path,
            FILE_READ_ATTRIBUTES | FILE_WRITE_DATA,
            FILE_OPEN_IF,
            FILE_NON_DIRECTORY_FILE,
        )?;
        let mut file = std::fs::File::from(handle);
        validate_regular_file(&file, &path)?;
        file.set_len(0)?;
        file.write_all(&contents)
    })
    .await
    .map_err(|error| io::Error::other(format!("filesystem task failed: {error}")))?
}

pub(super) async fn metadata(path: PathBuf) -> io::Result<std::fs::Metadata> {
    tokio::task::spawn_blocking(move || open_entry(&path)?.metadata())
        .await
        .map_err(|error| io::Error::other(format!("filesystem task failed: {error}")))?
}

fn create_directory_sync(path: &Path, recursive: bool) -> io::Result<()> {
    if !recursive {
        open_handle(path, FILE_READ_ATTRIBUTES, FILE_CREATE, FILE_DIRECTORY_FILE)?;
        return Ok(());
    }

    let mut current = PathBuf::new();
    for component in path.components() {
        current.push(component.as_os_str());
        if matches!(component, Component::Normal(_)) {
            open_or_create_directory(&current)?;
        }
    }
    Ok(())
}

fn open_or_create_directory(path: &Path) -> io::Result<()> {
    match open_handle(path, FILE_READ_ATTRIBUTES, FILE_OPEN, FILE_DIRECTORY_FILE) {
        Ok(_) => Ok(()),
        Err(error) if error.kind() == io::ErrorKind::NotFound => {
            match open_handle(path, FILE_READ_ATTRIBUTES, FILE_CREATE, FILE_DIRECTORY_FILE) {
                Ok(_) => Ok(()),
                Err(error) if error.kind() == io::ErrorKind::AlreadyExists => {
                    open_handle(path, FILE_READ_ATTRIBUTES, FILE_OPEN, FILE_DIRECTORY_FILE)?;
                    Ok(())
                }
                Err(error) => Err(error),
            }
        }
        Err(error) => Err(error),
    }
}

pub(super) async fn create_directory(path: PathBuf, recursive: bool) -> io::Result<()> {
    tokio::task::spawn_blocking(move || create_directory_sync(&path, recursive))
        .await
        .map_err(|error| io::Error::other(format!("filesystem task failed: {error}")))?
}

fn remove_sync(path: &Path, recursive: bool, force: bool) -> io::Result<()> {
    if recursive {
        return Err(io::Error::new(
            io::ErrorKind::Unsupported,
            "recursive no-follow removal is unsupported",
        ));
    }

    let metadata = match open_entry(path).and_then(|file| file.metadata()) {
        Ok(metadata) => metadata,
        Err(error) if force && error.kind() == io::ErrorKind::NotFound => return Ok(()),
        Err(error) => return Err(error),
    };
    let create_options = if metadata.is_dir() {
        FILE_DIRECTORY_FILE
    } else {
        FILE_NON_DIRECTORY_FILE
    };
    let handle = open_handle(path, DELETE, FILE_OPEN, create_options)?;
    let disposition = FILE_DISPOSITION_INFO {
        DeleteFile: BOOLEAN_TRUE,
    };
    let result = unsafe {
        SetFileInformationByHandle(
            handle.as_raw_handle() as HANDLE,
            FileDispositionInfo,
            (&raw const disposition).cast(),
            size_of::<FILE_DISPOSITION_INFO>() as u32,
        )
    };
    if result == 0 {
        return Err(io::Error::last_os_error());
    }
    drop(handle);
    Ok(())
}

pub(super) async fn remove(path: PathBuf, recursive: bool, force: bool) -> io::Result<()> {
    tokio::task::spawn_blocking(move || remove_sync(&path, recursive, force))
        .await
        .map_err(|error| io::Error::other(format!("filesystem task failed: {error}")))?
}

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