win_cf_api 0.0.1

use std::{fs, os::windows::prelude::MetadataExt, path::Path, slice};

use widestring::U16CString;
use windows::{
    core::{self, PCWSTR},
    Win32::{
        Foundation,
        Storage::{
            CloudFilters::{
                self, CfCreatePlaceholders, CF_FS_METADATA, CF_PLACEHOLDER_CREATE_INFO,
            },
            FileSystem::{FILE_ATTRIBUTE_DIRECTORY, FILE_ATTRIBUTE_NORMAL, FILE_BASIC_INFO},
        },
    },
};

use crate::usn::Usn;

// TODO: this struct could probably have a better name to represent files/dirs
/// A builder for creating new placeholder files/directories.
#[repr(transparent)]
#[derive(Debug)]
pub struct PlaceholderFile(CF_PLACEHOLDER_CREATE_INFO);

impl PlaceholderFile {
    /// Creates a new [PlaceholderFile][crate::PlaceholderFile].
    pub fn new(relative_path: impl AsRef<Path>) -> Self {
        Self(CF_PLACEHOLDER_CREATE_INFO {
            RelativeFileName: PCWSTR(
                U16CString::from_os_str(relative_path.as_ref())
                    .unwrap()
                    .into_raw(),
            ),
            Flags: CloudFilters::CF_PLACEHOLDER_CREATE_FLAG_NONE,
            Result: Foundation::S_OK,
            ..Default::default()
        })
    }

    /// Marks this [PlaceholderFile][crate::PlaceholderFile] as having no child placeholders on
    /// creation.
    ///
    /// If [PopulationType::Full][crate::PopulationType] is specified on registration, this flag
    /// will prevent [SyncFilter::fetch_placeholders][crate::SyncFilter::fetch_placeholders] from
    /// being called for this placeholder.
    ///
    /// Only applicable to placeholder directories.
    pub fn has_no_children(mut self) -> Self {
        self.0.Flags |= CloudFilters::CF_PLACEHOLDER_CREATE_FLAG_DISABLE_ON_DEMAND_POPULATION;
        self
    }

    /// Marks the [PlaceholderFile][crate::PlaceholderFile] as synced.
    ///
    /// This flag is used to determine the status of a placeholder shown in the file explorer. It
    /// is applicable to both files and directories.
    ///
    /// A file or directory should be marked as "synced" when it has all of its data and metadata.
    /// A file that is partially full could still be marked as synced, any remaining data will
    /// invoke the [SyncFilter::fetch_data][crate::SyncFilter::fetch_data] callback automatically
    /// if requested.
    pub fn mark_sync(mut self) -> Self {
        self.0.Flags |= CloudFilters::CF_PLACEHOLDER_CREATE_FLAG_MARK_IN_SYNC;
        self
    }

    /// Whether or not to overwrite an existing placeholder.
    pub fn overwrite(mut self) -> Self {
        self.0.Flags |= CloudFilters::CF_PLACEHOLDER_CREATE_FLAG_SUPERSEDE;
        self
    }

    /// Blocks this placeholder file from being dehydrated.
    ///
    /// This flag does not work on directories.
    pub fn block_dehydration(mut self) -> Self {
        self.0.Flags |= CloudFilters::CF_PLACEHOLDER_CREATE_FLAG_ALWAYS_FULL;
        self
    }

    /// The metadata for the [PlaceholderFile][crate::PlaceholderFile].
    pub fn metadata(mut self, metadata: Metadata) -> Self {
        self.0.FsMetadata = metadata.0;
        self
    }

    /// A buffer of bytes stored with the file that could be accessed through a
    /// [Request::file_blob][crate::Request::file_blob] or
    /// [FileExit::placeholder_info][crate::ext::FileExt::placeholder_info].
    ///
    /// The buffer must not exceed
    /// [4KiB](https://microsoft.github.io/windows-docs-rs/doc/windows/Win32/Storage/CloudFilters/constant.CF_PLACEHOLDER_MAX_FILE_IDENTITY_LENGTH.html).
    pub fn blob(mut self, blob: Vec<u8>) -> Self {
        assert!(
            blob.len() <= CloudFilters::CF_PLACEHOLDER_MAX_FILE_IDENTITY_LENGTH as usize,
            "blob size must not exceed {} bytes, got {} bytes",
            CloudFilters::CF_PLACEHOLDER_MAX_FILE_IDENTITY_LENGTH,
            blob.len()
        );

        if blob.is_empty() {
            return self;
        }

        let leaked_blob = Box::leak(blob.into_boxed_slice());

        self.0.FileIdentity = leaked_blob.as_ptr() as *const _;
        self.0.FileIdentityLength = leaked_blob.len() as _;

        self
    }

    /// Creates a placeholder file/directory on the file system.
    ///
    /// The value returned is the final [Usn][crate::Usn] after the placeholder is created.
    ///
    /// It is recommended to use this function over
    /// [FileExt::to_placeholder][crate::ext::FileExt::to_placeholder] for efficiency purposes. If you
    /// need to create multiple placeholders, consider using [BatchCreate][crate::BatchCreate].
    ///
    /// If you need to create placeholders from the [SyncFilter::fetch_placeholders][crate::SyncFilter::fetch_placeholders] callback, do not use this method. Instead, use
    /// [FetchPlaceholders::pass_with_placeholders][crate::ticket::FetchPlaceholders::pass_with_placeholders].
    pub fn create(self, parent: &Path) -> core::Result<Usn> {
        unsafe {
            CfCreatePlaceholders(
                PCWSTR::from_raw(U16CString::from_os_str(parent).unwrap().as_ptr()),
                &mut [self.0],
                CloudFilters::CF_CREATE_FLAG_NONE,
                None,
            )?;
        }

        self.0.Result.ok().map(|_| self.0.CreateUsn as Usn)
    }
}

impl Drop for PlaceholderFile {
    fn drop(&mut self) {
        // Safety: `self.0.RelativeFileName.0` is a valid pointer to a valid UTF-16 string
        drop(unsafe { U16CString::from_ptr_str(self.0.RelativeFileName.0) });

        if !self.0.FileIdentity.is_null() {
            // Safety: `self.0.FileIdentity` is a valid pointer to a valid slice
            drop(unsafe {
                Box::from_raw(slice::from_raw_parts_mut(
                    self.0.FileIdentity as *mut u8,
                    self.0.FileIdentityLength as _,
                ))
            });
        }
    }
}

/// Creates multiple placeholder file/directories within the given path.
pub trait BatchCreate {
    fn create<P: AsRef<Path>>(&mut self, path: P) -> core::Result<Vec<core::Result<Usn>>>;
}

impl BatchCreate for [PlaceholderFile] {
    fn create<P: AsRef<Path>>(&mut self, path: P) -> core::Result<Vec<core::Result<Usn>>> {
        unsafe {
            CfCreatePlaceholders(
                PCWSTR::from_raw(U16CString::from_os_str(path.as_ref()).unwrap().as_ptr()),
                // TODO: we should be able to cast it directly to its inner type
                &mut self
                    .iter()
                    .map(|placeholder| placeholder.0)
                    .collect::<Vec<_>>(),
                CloudFilters::CF_CREATE_FLAG_NONE,
                None,
            )?;
        }

        Ok(self
            .iter()
            .map(|placeholder| {
                placeholder
                    .0
                    .Result
                    .ok()
                    .map(|_| placeholder.0.CreateUsn as Usn)
            })
            .collect())
    }
}

/// The metadata for a [PlaceholderFile][crate::PlaceholderFile].
#[derive(Debug, Clone, Copy)]
pub struct Metadata(pub(crate) CF_FS_METADATA);

impl Metadata {
    pub fn file() -> Self {
        Self(CF_FS_METADATA {
            BasicInfo: FILE_BASIC_INFO {
                FileAttributes: FILE_ATTRIBUTE_NORMAL.0,
                ..Default::default()
            },
            ..Default::default()
        })
    }

    pub fn directory() -> Self {
        Self(CF_FS_METADATA {
            BasicInfo: FILE_BASIC_INFO {
                FileAttributes: FILE_ATTRIBUTE_DIRECTORY.0,
                ..Default::default()
            },
            ..Default::default()
        })
    }

    /// The time the file/directory was created.
    pub fn creation_time(mut self, time: u64) -> Self {
        self.0.BasicInfo.CreationTime = time as i64;
        self
    }

    /// The time the file/directory was last accessed.
    pub fn last_access_time(mut self, time: u64) -> Self {
        self.0.BasicInfo.LastAccessTime = time as i64;
        self
    }

    /// The time the file/directory content was last written.
    pub fn last_write_time(mut self, time: u64) -> Self {
        self.0.BasicInfo.LastWriteTime = time as i64;
        self
    }

    /// The time the file/directory content or metadata was changed.
    pub fn change_time(mut self, time: u64) -> Self {
        self.0.BasicInfo.ChangeTime = time as i64;
        self
    }

    /// The size of the file's content.
    pub fn size(mut self, size: u64) -> Self {
        self.0.FileSize = size as i64;
        self
    }


    // TODO: create a method for specifying that it's a directory.
    /// File attributes.
    pub fn attributes(mut self, attributes: u32) -> Self {
        self.0.BasicInfo.FileAttributes |= attributes;
        self
    }
}

impl From<fs::Metadata> for Metadata {
    fn from(metadata: fs::Metadata) -> Self {
        Self(CF_FS_METADATA {
            BasicInfo: FILE_BASIC_INFO {
                CreationTime: metadata.creation_time() as i64,
                LastAccessTime: metadata.last_access_time() as i64,
                LastWriteTime: metadata.last_write_time() as i64,
                ChangeTime: metadata.last_write_time() as i64,
                FileAttributes: metadata.file_attributes(),
            },
            FileSize: metadata.file_size() as i64,
        })
    }
}