use chrono::{DateTime, Utc};
use std::fs;
use std::path::Path;

/// Returns the age of a path as a [DateTime].
/// - If the path doesn't exist, returns [None]
/// - If it's a file, returns the modified time
/// - If it's a directory, returns the LATEST modified time of all files within
pub fn path_ts_latest(path: impl AsRef<Path>) -> Result<Option<DateTime<Utc>>, std::io::Error> {
	let path = path.as_ref();
	if !path.exists() {
		return Ok(None);
	}

	let metadata = fs::metadata(path)?;

	if metadata.is_file() {
		let modified = metadata.modified()?;
		Ok(Some(modified.into()))
	} else if metadata.is_dir() {
		find_latest_modified(path)
	} else {
		Ok(None)
	}
}

/// Returns the age of a path as a [DateTime].
/// - If the path doesn't exist, returns [None]
/// - If it's a file, returns the modified time
/// - If it's a directory, returns the EARLIEST modified time of all files within
pub fn path_ts_earliest(path: impl AsRef<Path>) -> Result<Option<DateTime<Utc>>, std::io::Error> {
	let path = path.as_ref();
	if !path.exists() {
		return Ok(None);
	}

	let metadata = fs::metadata(path)?;

	if metadata.is_file() {
		let modified = metadata.modified()?;
		Ok(Some(modified.into()))
	} else if metadata.is_dir() {
		find_earliest_modified(path)
	} else {
		Ok(None)
	}
}

fn find_latest_modified(dir: &Path) -> Result<Option<DateTime<Utc>>, std::io::Error> {
	let mut latest: Option<DateTime<Utc>> = None;

	// Include the directory's own modification time
	let dir_metadata = fs::metadata(dir)?;
	if let Ok(modified) = dir_metadata.modified() {
		let dt: DateTime<Utc> = modified.into();
		latest = Some(dt);
	}

	let entries = fs::read_dir(dir)?;

	for entry in entries.flatten() {
		let path = entry.path();
		let metadata = entry.metadata()?;

		if metadata.is_file() {
			if let Ok(modified) = metadata.modified() {
				let dt: DateTime<Utc> = modified.into();
				latest = Some(match latest {
					Some(prev) if prev > dt => prev,
					_ => dt,
				});
			}
		} else if metadata.is_dir()
			&& let Some(dir_latest) = find_latest_modified(&path)?
		{
			latest = Some(match latest {
				Some(prev) if prev > dir_latest => prev,
				_ => dir_latest,
			});
		}
	}

	return Ok(latest);
}

fn find_earliest_modified(dir: &Path) -> Result<Option<DateTime<Utc>>, std::io::Error> {
	let mut earliest: Option<DateTime<Utc>> = None;

	// Include the directory's own modification time
	let dir_metadata = fs::metadata(dir)?;
	if let Ok(modified) = dir_metadata.modified() {
		let dt: DateTime<Utc> = modified.into();
		earliest = Some(dt);
	}

	let entries = fs::read_dir(dir)?;

	for entry in entries.flatten() {
		let path = entry.path();
		let metadata = entry.metadata()?;

		if metadata.is_file() {
			if let Ok(modified) = metadata.modified() {
				let dt: DateTime<Utc> = modified.into();
				earliest = Some(match earliest {
					Some(prev) if prev < dt => prev,
					_ => dt,
				});
			}
		} else if metadata.is_dir()
			&& let Some(dir_earliest) = find_earliest_modified(&path)?
		{
			earliest = Some(match earliest {
				Some(prev) if prev < dir_earliest => prev,
				_ => dir_earliest,
			});
		}
	}

	return Ok(earliest);
}