//! Datatypes for the program
use super::*;
use std::fs::Metadata;
use tokio::time::Duration;

/// How many unprocessed insertion requests are allowed in the backlog before the insertion stream backpressures?
pub const CACHE_SEND_BUFFER_SIZE: usize = 30;
/// How many insertion requests should be grouped before emitting them all as blocks downstream.
pub const CACHE_GATE_BUFFER_SIZE: usize = 80;
/// How long should a partial block be kept in the gate buffer with an open upstream before being sent by force.
pub const CACHE_GATE_TIMEOUT: Duration = duration!(100 ms);
/// How long should the insertion stream be forced to wait before accepting new blocks to insert.
pub const CACHE_GATED_LAG: Duration = duration!(10 ms);

mod cache; pub use cache::Cache;
pub mod graph;
pub use graph::{
    INodeInfoGraph,
    HierarchicalINodeGraph,
    FsObjKind as FsKind,
    INodeInfoGraphEntry,
};

/// A raw file or directory inode number
///
/// Ususally created from the `.inode()` extension method on `fs::Metadata` found in prelude.
/// Can also be created with `new()` from a `fs::Metadata` reference, or created unsafely from an arbitrary `u64` with `new_unchecked`.
#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Copy)]
#[cfg_attr(feature="inspect", derive(serde::Serialize, serde::Deserialize))]
#[repr(transparent)]
pub struct INode(u64);

impl INode
{
    /// Create a new `INode` wrapper from any `u64` without checking if it is a real inode.
    #[inline] pub const unsafe fn new_unchecked(ino: u64) -> Self
    {
	Self(ino)
    }

    /// Get `ino` from an `fs::Metadata` object.
    #[inline] pub fn new(meta: &Metadata) -> Self
    {
	use std::os::unix::fs::MetadataExt as _;
	Self(meta.ino())
    }

    /// Convert into raw `u64` inode number.
    #[inline] pub const fn into_inner(self) -> u64
    {
	self.0
    }
}

impl<'a> From<&'a Metadata> for INode
{
    #[inline] fn from(from: &'a Metadata) -> Self
    {
	from.inode()
    }
}

impl From<INode> for u64
{
    #[inline] fn from(from: INode) -> Self
    {
	from.0
    }
}



/// A valid file system info
///
/// # Note
/// This does not contains the INode of the fs object itself, that is considered that key to the table.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum FsInfo
{
    File(u64, INode), //Size, parent dir inode
    Directory(INode), // Parent dir inode
}

impl FsInfo
{
    /// Is this entry a directory
    #[inline] pub fn is_dir(&self) -> bool
    {
	if let Self::Directory(_) = self
	{
	    true
	}
	else {
	    false
	}
    }
}


#[cfg(test)]
mod tests
{
    use super::*;
    #[tokio::test]
    async fn cache_insert_and_consume()
    {
	let mut cache = Cache::new();
	for x in 0..500
	{
	    cache.insert(unsafe { INode::new_unchecked(x) }, FsInfo::Directory).await;
	}
	let output = cache.try_complete().await.unwrap();
	assert_eq!(output.len(), 500);
	for x in 0..500
	{
	    assert_eq!(output.get(&unsafe { INode::new_unchecked(x) }).unwrap(), &FsInfo::Directory);
	}
    }
}