diff --git a/src/bot.rs b/src/bot.rs
index 3071a21..c5a5c0c 100644
--- a/src/bot.rs
+++ b/src/bot.rs
@@ -1,4 +1,5 @@
 pub enum Error{
+	InvalidHeader,
 	InvalidSegment,
 }
 
@@ -53,6 +54,9 @@ pub struct StreamableBot{
 	timeline:timeline::Timeline<SegmentId>,
 }
 impl StreamableBot{
+	pub fn new(file:crate::file::File)->Result<Self,Error>{
+		Err(Error::InvalidHeader)
+	}
 	pub fn load_segment(&mut self,segment_id:u64)->Result<Segment,Error>{
 		//load region from disk
 		//parse the models and determine what resources need to be loaded
diff --git a/src/demo.rs b/src/demo.rs
index ea66dc5..486f861 100644
--- a/src/demo.rs
+++ b/src/demo.rs
@@ -1,5 +1,5 @@
 pub enum Error{
-	//
+	InvalidHeader,
 }
 
 /*
@@ -20,4 +20,9 @@ how to do worldstate for deathrun!?
 pub struct StreamableDemo{
 	map:Box<crate::map::StreamableMap>,
 	bots:Vec<crate::bot::StreamableBot>,
+}
+impl StreamableDemo{
+	pub fn new(file:crate::file::File)->Result<Self,Error>{
+		Err(Error::InvalidHeader)
+	}
 }
\ No newline at end of file
diff --git a/src/file.rs b/src/file.rs
index 0c2b4b9..d9ebb14 100644
--- a/src/file.rs
+++ b/src/file.rs
@@ -33,16 +33,16 @@ for block_id in 0..num_blocks{
 //each block is compressed with zstd or gz or something
 
 */
-
-pub enum Magic{
-	Map,	//"SNFM"
-	Bot,	//"SNFB"
-	Demo,	//"SNFD"
+#[derive(Clone,Copy)]
+pub(crate) enum FourCC{
+	Map,
+	Bot,
+	Demo,
 }
 
-pub struct Header{
+struct Header{
 	/// Type of file
-	magic:Magic,
+	fourcc:FourCC,
 	/// Type version
 	version:u32,
 	/// Minimum data required to know the location of all streamable resources for this specific file
@@ -51,11 +51,28 @@ pub struct Header{
 	resource:u128,
 }
 
-pub struct BlockLayout{
+pub(crate) struct BlockLayout{
 	count:u64,
 	location:Vec<u64>,
 }
 
-pub struct File{
-	//???
+pub(crate) struct File{
+	header:Header,
+	block_layout:BlockLayout,
+	//reference to the data
+}
+
+impl File{
+	pub(crate) fn new<R:std::io::Read+std::io::Seek>(input:R)->Result<Self,Error>{
+		Self{
+			header:input.read_le()?,
+			block_layout:input.read_le()?,
+		}
+	}
+	pub(crate) fn read_block(&mut self,block_id:u64)->Result<Vec<u8>,Error>{
+		Err(Error::UnexpectedEOF)
+	}
+	pub(crate) fn fourcc(&self)->FourCC{
+		self.header.fourcc
+	}
 }
diff --git a/src/lib.rs b/src/lib.rs
index e36ef03..2777453 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,6 +6,7 @@ pub mod bot;
 pub mod demo;
 
 pub enum Error{
+	UnexpectedFourCC,
 	Header(file::Error),
 	Map(map::Error),
 	Bot(bot::Error),
@@ -18,9 +19,34 @@ pub enum SNF{
 	Demo(demo::StreamableDemo),
 }
 
-pub fn read<R:Read>(input:R)->Result<SNF,Error>{
-	//let header:file::Header=input.read()?;
-	Err(Error::Header(file::Error::InvalidMagic))
+pub fn read_snf<R:Read>(input:R)->Result<SNF,Error>{
+	let file=file::File::read(input).map_err(|e|Error::Header(e))?;
+	Ok(match file.fourcc(){
+		file::FourCC::Map=>SNF::Map(map::StreamableMap::new(file).map_err(|e|Error::Map(e))?),
+		file::FourCC::Bot=>SNF::Bot(bot::StreamableBot::new(file).map_err(|e|Error::Bot(e))?),
+		file::FourCC::Demo=>SNF::Demo(demo::StreamableDemo::new(file).map_err(|e|Error::Demo(e))?),
+	})
+}
+pub fn read_map<R:Read>(input:R)->Result<map::StreamableMap,Error>{
+	let file=file::File::read(input).map_err(|e|Error::Header(e))?;
+	match file.fourcc(){
+		file::FourCC::Map=>Ok(map::StreamableMap::new(file).map_err(|e|Error::Map(e))?),
+		_=>Err(Error::UnexpectedFourCC)
+	}
+}
+pub fn read_bot<R:Read>(input:R)->Result<bot::StreamableBot,Error>{
+	let file=file::File::read(input).map_err(|e|Error::Header(e))?;
+	match file.fourcc(){
+		file::FourCC::Bot=>Ok(bot::StreamableBot::new(file).map_err(|e|Error::Bot(e))?),
+		_=>Err(Error::UnexpectedFourCC)
+	}
+}
+pub fn read_demo<R:Read>(input:R)->Result<demo::StreamableDemo,Error>{
+	let file=file::File::read(input).map_err(|e|Error::Header(e))?;
+	match file.fourcc(){
+		file::FourCC::Demo=>Ok(demo::StreamableDemo::new(file).map_err(|e|Error::Demo(e))?),
+		_=>Err(Error::UnexpectedFourCC)
+	}
 }
 
 #[cfg(test)]
diff --git a/src/map.rs b/src/map.rs
index 19f7dc6..53e6501 100644
--- a/src/map.rs
+++ b/src/map.rs
@@ -1,4 +1,5 @@
 pub enum Error{
+	InvalidHeader,
 	InvalidNode,
 }
 
@@ -82,6 +83,9 @@ pub struct StreamableMap{
 	resource_image:std::collections::HashMap<ImageUuid,image::Image>,
 }
 impl StreamableMap{
+	pub fn new(file:crate::file::File)->Result<Self,Error>{
+		Err(Error::InvalidHeader)
+	}
 	pub fn load_node(&mut self,node_id:BvhNodeId)->Result<Vec<model::ModelInstance>,Error>{
 		//load region from disk
 		//parse the models and determine what resources need to be loaded