use super::*;
use std::{
    path::{
	Path
    },
    fs::{
	self,
	OpenOptions,
    },
    convert::{
	TryInto,
    },
    ops::{
	self,
    },
};

/// Handle a detected dupe
fn handle_dupe<P>(path: P, mode: &config::Mode) -> Result<(), error::Error>
where P: AsRef<Path>
{
    log!(Info, mode.logging_mode => " -> {:?}", path.as_ref());
    match mode.operation_mode
    {
	config::OperationMode::Delete => {
	    mode.error_mode.handle(std::fs::remove_file(path.as_ref()))?;
	},
	_ => (),
    }
    Ok(())
}

/// Handle a detected dupe async
#[inline(always)]
    #[cfg(feature="threads")]
async fn handle_dupe_async<P>(path: P, mode: &config::Mode) -> Result<(), error::Error>
where P: AsRef<Path>
{
    log!(Info, mode.logging_mode => " -> {:?}", path.as_ref());
    match mode.operation_mode
    {
	config::OperationMode::Delete => {
	    mode.error_mode.handle(tokio::fs::remove_file(path.as_ref()).await)?;
	},
	_ => (),
    }
    Ok(())
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub struct DupeCount
{
    pub total: usize,
    pub dupes: usize, 
}

impl From<bool> for DupeCount {
    fn from(b: bool) -> Self
    {
	Self{
	    total: 1,
	    dupes: if b {0} else {1},
	}
    }
}

impl ops::Add for DupeCount
{
    type Output = Self;
    fn add(self, other: Self) -> Self
    {
	Self {
	    total: self.total + other.total,
	    dupes: self.dupes + other.dupes,
	}
    }
}

impl ops::AddAssign for DupeCount
{
    fn add_assign(&mut self, other: Self)
    {
	*self = Self {
	    total: self.total + other.total,
	    dupes: self.dupes + other.dupes,
	};
    }
}

impl Default for DupeCount
{
    fn default() -> Self
    {
	Self{total:0, dupes:0}
    }
}

/// Process a file and add it to the table, returns true if is not a dupe.
pub fn process_file<P: AsRef<Path>>(file: P, set: &mut container::DupeMap) -> Result<bool, error::Error>
{
    let mut file = OpenOptions::new()
	.read(true)
	.open(file)?;
    let sz: usize = file.metadata()?.len().try_into().or(Err(error::Error::Arch(Some("Filesize is too large to be known. you have likely compiled the binary for 32-bit architecture or less. This shouldn't happen on 64-bit systems."))))?;
    
    let mut result = hash::Sha256Hash::default();
    error::check_size(sz, hash::compute(&mut file, &mut result)?)?;

    Ok(set.try_add(result))
}


/// Process a file and add it to the table, returns true if is not a dupe.
#[cfg(feature="threads")]
pub async fn process_file_async<P: AsRef<Path>>(file: P, set: &std::sync::Arc<tokio::sync::Mutex<container::DupeMap>>) -> Result<bool, error::Error>
{
    use tokio::{
	fs::{
	    OpenOptions,
	},
    };
    let mut file = OpenOptions::new()
	.read(true)
	.open(file).await?;
    let sz: usize = file.metadata().await?.len().try_into().or(Err(error::Error::Arch(Some("Filesize is too large to be known. you have likely compiled the binary for 32-bit architecture or less. This shouldn't happen on 64-bit systems."))))?;
    
    let mut result = hash::Sha256Hash::default();
    error::check_size(sz, hash::compute_async(&mut file, &mut result).await?)?;

    let mut set = set.lock().await;
    Ok(set.try_add(result))
}

/// Walk a dir structure and remove all dupes in it
pub fn do_dir<P: AsRef<Path>>(dir: P, depth: usize, set: &mut container::DupeMap, mode: &config::Mode) -> Result<DupeCount, error::Error>
{
    let recurse = match mode.recursion_mode {
	config::RecursionMode::N(n) if n > depth => true,
	config::RecursionMode::All => true,
	_ => false,
    };
    let cmode = mode;
    let mode = &mode.error_mode;
    let mut count = DupeCount::default();

    for obj in fs::read_dir(dir.as_ref())? //always return error if this fails
    {
	if let Some(obj) = mode.handle(obj)? { // Each one is allowed to fail if `mode` says so
	    let obj = obj.path();
	    
	    if obj.is_dir() && recurse {
		count += mode.handle(do_dir(obj, depth+1, set, cmode))?.unwrap_or_default();
	    } else {
		count += if mode.handle(process_file(&obj, set))?.unwrap_or_default() {
		    log!(Info, cmode.logging_mode => "OK {:?}", obj);
		    DupeCount{total: 1, dupes: 0}
		} else {
		    mode.handle(handle_dupe(obj, &cmode))?;
		    DupeCount{total: 1, dupes: 1}
		};
	    }
	}
    }
    
    Ok(count)
}

/// Walk a dir structure and remove all dupes in it
#[cfg(feature="threads")]
pub fn do_dir_async<P: AsRef<Path> + std::marker::Send + std::marker::Sync + 'static>(dir: P, depth: usize, set: std::sync::Arc<tokio::sync::Mutex<container::DupeMap>>, mode: config::Mode) -> futures::future::BoxFuture<'static, Result<DupeCount, error::Error>>
{
    use std::sync::Arc;
    use futures::future::{
	FutureExt
    };
    async move {
	let recurse = match mode.recursion_mode {
	    config::RecursionMode::N(n) if n > depth => true,
	    config::RecursionMode::All => true,
	    _ => false,
	};
	let cmode = mode;
	let mode = &cmode.error_mode;
	let mut children = Vec::new();
	let mut workers = Vec::new();

	let mut dir = tokio::fs::read_dir(dir.as_ref()).await?; //always return error if this fails
	
	while let Some(Some(obj)) = mode.handle(dir.next_entry().await)?
	{
	    let obj = obj.path();
	    
	    if obj.is_dir() && recurse {
		let set = Arc::clone(&set);
		let cmode = cmode.clone();
		let mode = mode.clone();
		children.push(tokio::task::spawn(async move {
		    log!(Info, cmode.logging_mode => "OK {:?}", obj);
		    match mode.handle(do_dir_async(obj, depth+1, set, cmode).await) {
			Ok(v) => Ok(v.unwrap_or_default()),
			Err(v) => Err(v),
		    }
		}));
	    } else {
		let set = Arc::clone(&set);
		let mode = mode.clone();
		let cmode = cmode.clone();
		workers.push(tokio::task::spawn(async move {
		    match mode.handle(process_file_async(&obj, &set).await) {
			Ok(v) => {
			    if v.unwrap_or_default() {
				log!(Info, cmode.logging_mode => "OK {:?}", obj);
				Ok(true)
			    } else {
				if let Err(e) = mode.handle(handle_dupe_async(obj, &cmode).await) {
				    Err(e)
				} else {
				    Ok(false)
				}
			    }
			},
			Err(v) => Err(v), 
		    }
		}));
	    }
	}

	async fn wait_on<T: IntoIterator<Item=tokio::task::JoinHandle<Result<U, error::Error>>>, U: Default+Into<DupeCount>>(children: T, mode: &error::Mode) -> Result<DupeCount, error::Error>
	{
	    let mut count = DupeCount::default();
	    for child in children.into_iter() { 
		count += mode.handle(error::internal(child.await)? /* thread panicked */)?.unwrap_or_default().into();
	    }
	    Ok(count)
	}

	// Wait for all children to complete before error checking.
	let er1 = wait_on(workers, &mode).await;
	let er2 = wait_on(children, &mode).await;
	Ok(er1? + er2?)
    }.boxed()
}