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    use crate::rust::{vec::Vec, borrow::ToOwned, string::String, cmp};
    use crate::io;

    use super::{deserialize_buffer, serialize, Deserialize, Serialize, Error, Uint32, External};
    use super::section::{
    	Section, CodeSection, TypeSection, ImportSection, ExportSection, FunctionSection,
    	GlobalSection, TableSection, ElementSection, DataSection, MemorySection,
    	CustomSection,
    };
    use super::name_section::NameSection;
    use super::reloc_section::RelocSection;

    const WASM_MAGIC_NUMBER: [u8; 4] = [0x00, 0x61, 0x73, 0x6d];

    /// WebAssembly module
    #[derive(Debug, Clone, PartialEq)]
    pub struct Module {
    	magic: u32,
    	version: u32,
    	sections: Vec<Section>,
    }

    #[derive(Debug, Clone, Copy, PartialEq)]
    /// Type of the import entry to count
    pub enum ImportCountType {
    	/// Count functions
    	Function,
    	/// Count globals
    	Global,
    	/// Count tables
    	Table,
    	/// Count memories
    	Memory,
    }

    impl Default for Module {
    	fn default() -> Self {
    		Module {
    			magic: u32::from_le_bytes(WASM_MAGIC_NUMBER),
    			version: 1,
    			sections: Vec::with_capacity(16),
    		}
    	}
    }

    impl Module {
    	/// New module with sections
    	pub fn new(sections: Vec<Section>) -> Self {
    		Module {
    			sections: sections, ..Default::default()
    		}
    	}

    	/// Construct a module from a slice.
    	pub fn from_bytes<T: AsRef<[u8]>>(input: T) -> Result<Self, Error> {
    		Ok(deserialize_buffer::<Module>(input.as_ref())?)
    	}

    	/// Serialize a module to a vector.
    	pub fn to_bytes(self) -> Result<Vec<u8>, Error> {
    		Ok(serialize::<Module>(self)?)
    	}

    	/// Destructure the module, yielding sections
    	pub fn into_sections(self) -> Vec<Section> {
    		self.sections
    	}

    	/// Version of module.
    	pub fn version(&self) -> u32 { self.version }

    	/// Sections list.
    	///
    	/// Each known section is optional and may appear at most once.
    	pub fn sections(&self) -> &[Section] {
    		&self.sections
    	}

    	/// Sections list (mutable).
    	///
    	/// Each known section is optional and may appear at most once.
    	pub fn sections_mut(&mut self) -> &mut Vec<Section> {
    		&mut self.sections
    	}

    	/// Insert a section, in the correct section ordering. This will fail with an error,
    	/// if the section can only appear once.
    	pub fn insert_section(&mut self, section: Section) -> Result<(), Error> {
    		let sections = self.sections_mut();

    		// Custom sections can be inserted anywhere. Lets always insert them last here.
    		if section.order() == 0 {
    			sections.push(section);
    			return Ok(());
    		}

    		// Check if the section already exists.
    		if sections.iter().position(|s| s.order() == section.order()).is_some() {
    			return Err(Error::DuplicatedSections(section.order()));
    		}

    		// Assume that the module is already well-ordered.
    		if let Some(pos) = sections.iter().position(|s| section.order() < s.order()) {
    			sections.insert(pos, section);
    		} else {
    			sections.push(section);
    		}

    		Ok(())
    	}

    	/// Code section reference, if any.
    	pub fn code_section(&self) -> Option<&CodeSection> {
    		for section in self.sections() {
    			if let &Section::Code(ref code_section) = section { return Some(code_section); }
    		}
    		None
    	}

    	/// Code section mutable reference, if any.
    	pub fn code_section_mut(&mut self) -> Option<&mut CodeSection> {
    		for section in self.sections_mut() {
    			if let Section::Code(ref mut code_section) = *section { return Some(code_section); }
    		}
    		None
    	}

    	/// Types section reference, if any.
    	pub fn type_section(&self) -> Option<&TypeSection> {
    		for section in self.sections() {
    			if let &Section::Type(ref type_section) = section { return Some(type_section); }
    		}
    		None
    	}

    	/// Types section mutable reference, if any.
    	pub fn type_section_mut(&mut self) -> Option<&mut TypeSection> {
    		for section in self.sections_mut() {
    			if let Section::Type(ref mut type_section) = *section { return Some(type_section); }
    		}
    		None
    	}

    	/// Imports section reference, if any.
    	pub fn import_section(&self) -> Option<&ImportSection> {
    		for section in self.sections() {
    			if let &Section::Import(ref import_section) = section { return Some(import_section); }
    		}
    		None
    	}

    	/// Imports section mutable reference, if any.
    	pub fn import_section_mut(&mut self) -> Option<&mut ImportSection> {
    		for section in self.sections_mut() {
    			if let Section::Import(ref mut import_section) = *section { return Some(import_section); }
    		}
    		None
    	}

    	/// Globals section reference, if any.
    	pub fn global_section(&self) -> Option<&GlobalSection> {
    		for section in self.sections() {
    			if let &Section::Global(ref section) = section { return Some(section); }
    		}
    		None
    	}

    		/// Globals section mutable reference, if any.
    	pub fn global_section_mut(&mut self) -> Option<&mut GlobalSection> {
    		for section in self.sections_mut() {
    			if let Section::Global(ref mut section) = *section { return Some(section); }
    		}
    		None
    	}

    	/// Exports section reference, if any.
    	pub fn export_section(&self) -> Option<&ExportSection> {
    		for section in self.sections() {
    			if let &Section::Export(ref export_section) = section { return Some(export_section); }
    		}
    		None
    	}

    	/// Exports section mutable reference, if any.
    	pub fn export_section_mut(&mut self) -> Option<&mut ExportSection> {
    		for section in self.sections_mut() {
    			if let Section::Export(ref mut export_section) = *section { return Some(export_section); }
    		}
    		None
    	}

    	/// Table section reference, if any.
    	pub fn table_section(&self) -> Option<&TableSection> {
    		for section in self.sections() {
    			if let &Section::Table(ref section) = section { return Some(section); }
    		}
    		None
    	}

    	/// Table section mutable reference, if any.
    	pub fn table_section_mut(&mut self) -> Option<&mut TableSection> {
    		for section in self.sections_mut() {
    			if let Section::Table(ref mut section) = *section { return Some(section); }
    		}
    		None
    	}

    	/// Data section reference, if any.
    	pub fn data_section(&self) -> Option<&DataSection> {
    		for section in self.sections() {
    			if let &Section::Data(ref section) = section { return Some(section); }
    		}
    		None
    	}

    	/// Data section mutable reference, if any.
    	pub fn data_section_mut(&mut self) -> Option<&mut DataSection> {
    		for section in self.sections_mut() {
    			if let Section::Data(ref mut section) = *section { return Some(section); }
    		}
    		None
    	}

    	/// Element section reference, if any.
    	pub fn elements_section(&self) -> Option<&ElementSection> {
    		for section in self.sections() {
    			if let &Section::Element(ref section) = section { return Some(section); }
    		}
    		None
    	}

    	/// Element section mutable reference, if any.
    	pub fn elements_section_mut(&mut self) -> Option<&mut ElementSection> {
    		for section in self.sections_mut() {
    			if let Section::Element(ref mut section) = *section { return Some(section); }
    		}
    		None
    	}

    	/// Memory section reference, if any.
    	pub fn memory_section(&self) -> Option<&MemorySection> {
    		for section in self.sections() {
    			if let &Section::Memory(ref section) = section { return Some(section); }
    		}
    		None
    	}

    	/// Memory section mutable reference, if any.
    	pub fn memory_section_mut(&mut self) -> Option<&mut MemorySection> {
    		for section in self.sections_mut() {
    			if let Section::Memory(ref mut section) = *section { return Some(section); }
    		}
    		None
    	}

    	/// Functions signatures section reference, if any.
    	pub fn function_section(&self) -> Option<&FunctionSection> {
    		for section in self.sections() {
    			if let &Section::Function(ref sect) = section { return Some(sect); }
    		}
    		None
    	}

    	/// Functions signatures section mutable reference, if any.
    	pub fn function_section_mut(&mut self) -> Option<&mut FunctionSection> {
    		for section in self.sections_mut() {
    			if let Section::Function(ref mut sect) = *section { return Some(sect); }
    		}
    		None
    	}

    	/// Start section, if any.
    	pub fn start_section(&self) -> Option<u32> {
    		for section in self.sections() {
    			if let &Section::Start(sect) = section { return Some(sect); }
    		}
    		None
    	}

    	/// Changes the module's start section.
    	pub fn set_start_section(&mut self, new_start: u32) {
    		for section in self.sections_mut().iter_mut() {
    			if let &mut Section::Start(_sect) = section {
    				*section = Section::Start(new_start);
    				return
    			}
    		}
    		// This should not fail, because we update the existing section above.
    		self.insert_section(Section::Start(new_start)).expect("insert_section should not fail");
    	}

    	/// Removes the module's start section.
    	pub fn clear_start_section(&mut self) {
    		let sections = self.sections_mut();
    		let mut rmidx = sections.len();
    		for (index, section) in sections.iter_mut().enumerate() {
    			if let Section::Start(_sect) = section {
    				rmidx = index;
    				break;
    			}
    		}
    		if rmidx < sections.len() {
    			sections.remove(rmidx);
    		}
    	}

    	/// Returns an iterator over the module's custom sections
    	pub fn custom_sections(&self) -> impl Iterator<Item=&CustomSection> {
    		self.sections().iter().filter_map(|s| {
    			if let Section::Custom(s) = s {
    				Some(s)
    			} else {
    				None
    			}
    		})
    	}

    	/// Sets the payload associated with the given custom section, or adds a new custom section,
    	/// as appropriate.
    	pub fn set_custom_section(&mut self, name: impl Into<String>, payload: Vec<u8>) {
    		let name: String = name.into();
    		for section in self.sections_mut() {
    			if let &mut Section::Custom(ref mut sect) = section {
    				if sect.name() == name {
    					*sect = CustomSection::new(name, payload);
    					return
    				}
    			}
    		}
    		self.sections_mut().push(Section::Custom(CustomSection::new(name, payload)));
    	}

    	/// Removes the given custom section, if it exists.
    	/// Returns the removed section if it existed, or None otherwise.
    	pub fn clear_custom_section(&mut self, name: impl AsRef<str>) -> Option<CustomSection> {
    		let name: &str = name.as_ref();

    		let sections = self.sections_mut();

    		for i in 0..sections.len() {
    			let mut remove = false;
    			if let Section::Custom(ref sect) = sections[i] {
    				if sect.name() == name {
    					remove = true;
    				}
    			}

    			if remove {
    				let removed = sections.remove(i);
    				match removed {
    					Section::Custom(sect) => return Some(sect),
    					_ => unreachable!(), // This is the section we just matched on, so...
    				}
    			}
    		}
    		None
    	}

    	/// True if a name section is present.
    	///
    	/// NOTE: this can return true even if the section was not parsed, hence `names_section()` may return `None`
    	///       even if this returns `true`
    	pub fn has_names_section(&self) -> bool {
    		self.sections().iter().any(|e| {
    			match e {
    				// The default case, when the section was not parsed
    				Section::Custom(custom) => custom.name() == "name",
    				// This is the case, when the section was parsed
    				Section::Name(_) => true,
    				_ => false,
    			}
    		})
    	}

    	/// Functions signatures section reference, if any.
    	///
    	/// NOTE: name section is not parsed by default so `names_section` could return None even if name section exists.
    	/// Call `parse_names` to parse name section
    	pub fn names_section(&self) -> Option<&NameSection> {
    		for section in self.sections() {
    			if let Section::Name(ref sect) = *section { return Some(sect); }
    		}
    		None
    	}

    	/// Functions signatures section mutable reference, if any.
    	///
    	/// NOTE: name section is not parsed by default so `names_section` could return None even if name section exists.
    	/// Call `parse_names` to parse name section
    	pub fn names_section_mut(&mut self) -> Option<&mut NameSection> {
    		for section in self.sections_mut() {
    			if let Section::Name(ref mut sect) = *section { return Some(sect); }
    		}
    		None
    	}

    	/// Try to parse name section in place.
    	///
    	/// Corresponding custom section with proper header will convert to name sections
    	/// If some of them will fail to be decoded, Err variant is returned with the list of
    	/// (index, Error) tuples of failed sections.
    	pub fn parse_names(mut self) -> Result<Self, (Vec<(usize, Error)>, Self)> {
    		let mut parse_errors = Vec::new();

    		for i in 0..self.sections.len() {
    			if let Some(name_section) = {
    				let section = self.sections.get(i).expect("cannot fail because i in range 0..len; qed");
    				if let Section::Custom(ref custom) = *section {
    					if custom.name() == "name" {
    						let mut rdr = io::Cursor::new(custom.payload());
    						let name_section = match NameSection::deserialize(&self, &mut rdr) {
    							Ok(ns) => ns,
    							Err(e) => { parse_errors.push((i, e)); continue; }
    						};
    						Some(name_section)
    					} else {
    						None
    					}
    				} else { None }
    			} {
    				// todo: according to the spec a Wasm binary can contain only one name section
    				*self.sections.get_mut(i).expect("cannot fail because i in range 0..len; qed") = Section::Name(name_section);
    			}
    		}

    		if parse_errors.len() > 0 {
    			Err((parse_errors, self))
    		} else {
    			Ok(self)
    		}
    	}

    	/// Try to parse reloc section in place.
    	///
    	/// Corresponding custom section with proper header will convert to reloc sections
    	/// If some of them will fail to be decoded, Err variant is returned with the list of
    	/// (index, Error) tuples of failed sections.
    	pub fn parse_reloc(mut self) -> Result<Self, (Vec<(usize, Error)>, Self)> {
    		let mut parse_errors = Vec::new();

    		for (i, section) in self.sections.iter_mut().enumerate() {
    			if let Some(relocation_section) = {
    				if let Section::Custom(ref custom) = *section {
    					if custom.name().starts_with("reloc.") {
    						let mut rdr = io::Cursor::new(custom.payload());
    						let reloc_section = match RelocSection::deserialize(custom.name().to_owned(), &mut rdr) {
    							Ok(reloc_section) => reloc_section,
    							Err(e) => { parse_errors.push((i, e)); continue; }
    						};
    						if rdr.position() != custom.payload().len() {
    							parse_errors.push((i, io::Error::InvalidData.into()));
    							continue;
    						}
    						Some(Section::Reloc(reloc_section))
    					}
    					else {
    						None
    					}
    				}
    				else {
    					None
    				}
    			} {
    				*section = relocation_section;
    			}
    		}

    		if parse_errors.len() > 0 {
    			Err((parse_errors, self))
    		} else {
    			Ok(self)
    		}
    	}

    	/// Count imports by provided type.
    	pub fn import_count(&self, count_type: ImportCountType) -> usize {
    		self.import_section()
    			.map(|is|
    				is.entries().iter().filter(|import| match (count_type, *import.external()) {
    					(ImportCountType::Function, External::Function(_)) => true,
    					(ImportCountType::Global, External::Global(_)) => true,
    					(ImportCountType::Table, External::Table(_)) => true,
    					(ImportCountType::Memory, External::Memory(_)) => true,
    					_ => false
    				}).count())
    			.unwrap_or(0)
    	}

    	/// Query functions space.
    	pub fn functions_space(&self) -> usize {
    		self.import_count(ImportCountType::Function) +
    			self.function_section().map(|fs| fs.entries().len()).unwrap_or(0)
    	}

    	/// Query globals space.
    	pub fn globals_space(&self) -> usize {
    		self.import_count(ImportCountType::Global) +
    			self.global_section().map(|gs| gs.entries().len()).unwrap_or(0)
    	}

    	/// Query table space.
    	pub fn table_space(&self) -> usize {
    		self.import_count(ImportCountType::Table) +
    			self.table_section().map(|ts| ts.entries().len()).unwrap_or(0)
    	}

    	/// Query memory space.
    	pub fn memory_space(&self) -> usize {
    		self.import_count(ImportCountType::Memory) +
    			self.memory_section().map(|ms| ms.entries().len()).unwrap_or(0)
    	}
    }

    impl Deserialize for Module {
    	type Error = super::Error;

    	fn deserialize<R: io::Read>(reader: &mut R) -> Result<Self, Self::Error> {
    		let mut sections = Vec::new();

    		let mut magic = [0u8; 4];
    		reader.read(&mut magic)?;
    		if magic != WASM_MAGIC_NUMBER {
    			return Err(Error::InvalidMagic);
    		}

    		let version: u32 = Uint32::deserialize(reader)?.into();

    		if version != 1 {
    			return Err(Error::UnsupportedVersion(version));
    		}

    		let mut last_section_order = 0;

    		loop {
    			match Section::deserialize(reader) {
    				Err(Error::UnexpectedEof) => { break; },
    				Err(e) => { return Err(e) },
    				Ok(section) => {
    					if section.order() != 0 {
    						if last_section_order > section.order() {
    							return Err(Error::SectionsOutOfOrder);
    						} else if last_section_order == section.order() {
    							return Err(Error::DuplicatedSections(last_section_order));
    						}
    						last_section_order = section.order();
    					}
    					sections.push(section);
    				}
    			}
    		}

    		let module = Module {
    			magic: u32::from_le_bytes(magic),
    			version: version,
    			sections: sections,
    		};

    		if module.code_section().map(|cs| cs.bodies().len()).unwrap_or(0) !=
    			module.function_section().map(|fs| fs.entries().len()).unwrap_or(0)
    		{
    			return Err(Error::InconsistentCode);
    		}

    		Ok(module)
    	}
    }

    impl Serialize for Module {
    	type Error = Error;

    	fn serialize<W: io::Write>(self, w: &mut W) -> Result<(), Self::Error> {
    		Uint32::from(self.magic).serialize(w)?;
    		Uint32::from(self.version).serialize(w)?;
    		for section in self.sections.into_iter() {
    			// todo: according to the spec the name section should appear after the data section
    			section.serialize(w)?;
    		}
    		Ok(())
    	}
    }

    #[derive(Debug, Copy, Clone, PartialEq)]
    struct PeekSection<'a> {
    	cursor: usize,
    	region: &'a [u8],
    }

    impl<'a> io::Read for PeekSection<'a> {
    	fn read(&mut self, buf: &mut [u8]) -> io::Result<()> {
    		let available = cmp::min(buf.len(), self.region.len() - self.cursor);
    		if available < buf.len() {
    			return Err(io::Error::UnexpectedEof);
    		}

    		let range = self.cursor..self.cursor + buf.len();
    		buf.copy_from_slice(&self.region[range]);

    		self.cursor += available;
    		Ok(())
    	}
    }

    /// Returns size of the module in the provided stream.
    pub fn peek_size(source: &[u8]) -> usize {
    	if source.len() < 9 {
    		return 0;
    	}

    	let mut cursor = 8;
    	loop {
    		let (new_cursor, section_id, section_len) = {
    			let mut peek_section = PeekSection { cursor: 0, region: &source[cursor..] };
    			let section_id: u8 = match super::VarUint7::deserialize(&mut peek_section) {
    				Ok(res) => res.into(),
    				Err(_) => { break; },
    			};
    			let section_len: u32 = match super::VarUint32::deserialize(&mut peek_section) {
    				Ok(res) => res.into(),
    				Err(_) => { break; },
    			};

    			(peek_section.cursor, section_id, section_len)
    		};

    		if section_id <= 11 && section_len > 0 {
    			let next_cursor = cursor + new_cursor + section_len as usize;
    			if next_cursor > source.len() {
    				break;
    			} else if next_cursor == source.len() {
    				cursor = next_cursor;
    				break;
    			}
    			cursor = next_cursor;
    		} else {
    			break;
    		}
    	}

    	cursor
    }

    #[cfg(test)]
    mod integration_tests {
    	use super::super::{deserialize_file, serialize, deserialize_buffer, Section, TypeSection, FunctionSection, ExportSection, CodeSection};
    	use super::Module;

    	#[test]
    	fn hello() {
    		let module = deserialize_file("./res/cases/v1/hello.wasm").expect("Should be deserialized");

    		assert_eq!(module.version(), 1);
    		assert_eq!(module.sections().len(), 8);
    	}

    	#[test]
    	fn serde() {
    		let module = deserialize_file("./res/cases/v1/test5.wasm").expect("Should be deserialized");
    		let buf = serialize(module).expect("serialization to succeed");

    		let module_new: Module = deserialize_buffer(&buf).expect("deserialization to succeed");
    		let module_old = deserialize_file("./res/cases/v1/test5.wasm").expect("Should be deserialized");

    		assert_eq!(module_old.sections().len(), module_new.sections().len());
    	}

    	#[test]
    	fn serde_type() {
    		let mut module = deserialize_file("./res/cases/v1/test5.wasm").expect("Should be deserialized");
    		module.sections_mut().retain(|x| {
    			if let &Section::Type(_) = x { true } else { false }
    		});

    		let buf = serialize(module).expect("serialization to succeed");

    		let module_new: Module = deserialize_buffer(&buf).expect("deserialization to succeed");
    		let module_old = deserialize_file("./res/cases/v1/test5.wasm").expect("Should be deserialized");
    		assert_eq!(
    			module_old.type_section().expect("type section exists").types().len(),
    			module_new.type_section().expect("type section exists").types().len(),
    			"There should be equal amount of types before and after serialization"
    		);
    	}

    	#[test]
    	fn serde_import() {
    		let mut module = deserialize_file("./res/cases/v1/test5.wasm").expect("Should be deserialized");
    		module.sections_mut().retain(|x| {
    			if let &Section::Import(_) = x { true } else { false }
    		});

    		let buf = serialize(module).expect("serialization to succeed");

    		let module_new: Module = deserialize_buffer(&buf).expect("deserialization to succeed");
    		let module_old = deserialize_file("./res/cases/v1/test5.wasm").expect("Should be deserialized");
    		assert_eq!(
    			module_old.import_section().expect("import section exists").entries().len(),
    			module_new.import_section().expect("import section exists").entries().len(),
    			"There should be equal amount of import entries before and after serialization"
    		);
    	}

    	#[test]
    	fn serde_code() {
    		let mut module = deserialize_file("./res/cases/v1/test5.wasm").expect("Should be deserialized");
    		module.sections_mut().retain(|x| {
    			if let &Section::Code(_) = x { return true }
    			if let &Section::Function(_) = x { true } else { false }
    		});

    		let buf = serialize(module).expect("serialization to succeed");

    		let module_new: Module = deserialize_buffer(&buf).expect("deserialization to succeed");
    		let module_old = deserialize_file("./res/cases/v1/test5.wasm").expect("Should be deserialized");
    		assert_eq!(
    			module_old.code_section().expect("code section exists").bodies().len(),
    			module_new.code_section().expect("code section exists").bodies().len(),
    			"There should be equal amount of function bodies before and after serialization"
    		);
    	}

    	#[test]
    	fn const_() {
    		use super::super::Instruction::*;

    		let module = deserialize_file("./res/cases/v1/const.wasm").expect("Should be deserialized");
    		let func = &module.code_section().expect("Code section to exist").bodies()[0];
    		assert_eq!(func.code().elements().len(), 20);

    		assert_eq!(I64Const(9223372036854775807), func.code().elements()[0]);
    		assert_eq!(I64Const(-9223372036854775808), func.code().elements()[1]);
    		assert_eq!(I64Const(-1152894205662152753), func.code().elements()[2]);
    		assert_eq!(I64Const(-8192), func.code().elements()[3]);
    		assert_eq!(I32Const(1024), func.code().elements()[4]);
    		assert_eq!(I32Const(2048), func.code().elements()[5]);
    		assert_eq!(I32Const(4096), func.code().elements()[6]);
    		assert_eq!(I32Const(8192), func.code().elements()[7]);
    		assert_eq!(I32Const(16384), func.code().elements()[8]);
    		assert_eq!(I32Const(32767), func.code().elements()[9]);
    		assert_eq!(I32Const(-1024), func.code().elements()[10]);
    		assert_eq!(I32Const(-2048), func.code().elements()[11]);
    		assert_eq!(I32Const(-4096), func.code().elements()[12]);
    		assert_eq!(I32Const(-8192), func.code().elements()[13]);
    		assert_eq!(I32Const(-16384), func.code().elements()[14]);
    		assert_eq!(I32Const(-32768), func.code().elements()[15]);
    		assert_eq!(I32Const(-2147483648), func.code().elements()[16]);
    		assert_eq!(I32Const(2147483647), func.code().elements()[17]);
    	}

    	#[test]
    	fn store() {
    		use super::super::Instruction::*;

    		let module = deserialize_file("./res/cases/v1/offset.wasm").expect("Should be deserialized");
    		let func = &module.code_section().expect("Code section to exist").bodies()[0];

    		assert_eq!(func.code().elements().len(), 5);
    		assert_eq!(I64Store(0, 32), func.code().elements()[2]);
    	}

    	#[test]
    	fn peek() {
    		use super::peek_size;

    		let module = deserialize_file("./res/cases/v1/test5.wasm").expect("Should be deserialized");
    		let mut buf = serialize(module).expect("serialization to succeed");

    		buf.extend_from_slice(&[1, 5, 12, 17]);

    		assert_eq!(peek_size(&buf), buf.len() - 4);
    	}

    	#[test]
    	fn peek_2() {
    		use super::peek_size;

    		let module = deserialize_file("./res/cases/v1/offset.wasm").expect("Should be deserialized");
    		let mut buf = serialize(module).expect("serialization to succeed");

    		buf.extend_from_slice(&[0, 0, 0, 0, 0, 1, 5, 12, 17]);

    		assert_eq!(peek_size(&buf), buf.len() - 9);
    	}

    	#[test]
    	fn peek_3() {
    		use super::peek_size;

    		let module = deserialize_file("./res/cases/v1/peek_sample.wasm").expect("Should be deserialized");
    		let buf = serialize(module).expect("serialization to succeed");

    		assert_eq!(peek_size(&buf), buf.len());
    	}

    	#[test]
    	fn module_default_round_trip() {
    		let module1 = Module::default();
    		let buf = serialize(module1).expect("Serialization should succeed");

    		let module2: Module = deserialize_buffer(&buf).expect("Deserialization should succeed");
    		assert_eq!(Module::default().magic, module2.magic);
    	}

    	#[test]
    	fn names() {
    		let module = deserialize_file("./res/cases/v1/with_names.wasm")
    			.expect("Should be deserialized")
    			.parse_names()
    			.expect("Names to be parsed");

    		let mut found_section = false;
    		for section in module.sections() {
    			match *section {
    				Section::Name(ref name_section) => {
    					let function_name_subsection = name_section
    						.functions()
    						.expect("function_name_subsection should be present");
    					assert_eq!(
    						function_name_subsection.names().get(0).expect("Should be entry #0"),
    						"elog"
    					);
    					assert_eq!(
    						function_name_subsection.names().get(11).expect("Should be entry #0"),
    						"_ZN48_$LT$pwasm_token_contract..Endpoint$LT$T$GT$$GT$3new17hc3ace6dea0978cd9E"
    					);

    					found_section = true;
    				},
    				_ => {},
    			}
    		}

    		assert!(found_section, "Name section should be present in dedicated example");
    	}

    	// This test fixture has FLAG_SHARED so it depends on atomics feature.
    	#[test]
    	fn shared_memory_flag() {
    		let module = deserialize_file("./res/cases/v1/varuint1_1.wasm");
    		assert_eq!(module.is_ok(), cfg!(feature="atomics"));
    	}

    	#[test]
    	fn memory_space() {
    		let module = deserialize_file("./res/cases/v1/two-mems.wasm").expect("failed to deserialize");
    		assert_eq!(module.memory_space(), 2);
    	}

        #[test]
        fn add_custom_section() {
            let mut module = deserialize_file("./res/cases/v1/start_mut.wasm").expect("failed to deserialize");
            assert!(module.custom_sections().next().is_none());
            module.set_custom_section("mycustomsection".to_string(), vec![1, 2, 3, 4]);
            {
    	        let sections = module.custom_sections().collect::<Vec<_>>();
    	        assert_eq!(sections.len(), 1);
    	        assert_eq!(sections[0].name(), "mycustomsection");
    	        assert_eq!(sections[0].payload(), &[1, 2, 3, 4]);
    	    }

            let old_section = module.clear_custom_section("mycustomsection");
            assert_eq!(old_section.expect("Did not find custom section").payload(), &[1, 2, 3, 4]);

            assert!(module.custom_sections().next().is_none());
        }

        #[test]
        fn mut_start() {
            let mut module = deserialize_file("./res/cases/v1/start_mut.wasm").expect("failed to deserialize");
            assert_eq!(module.start_section().expect("Did not find any start section"), 1);
            module.set_start_section(0);
            assert_eq!(module.start_section().expect("Did not find any start section"), 0);
            module.clear_start_section();
            assert_eq!(None, module.start_section());
        }

        #[test]
        fn add_start() {
            let mut module = deserialize_file("./res/cases/v1/start_add.wasm").expect("failed to deserialize");
            assert!(module.start_section().is_none());
            module.set_start_section(0);
            assert_eq!(module.start_section().expect("Did not find any start section"), 0);

            let sections = module.sections().iter().map(|s| s.order()).collect::<Vec<_>>();
            assert_eq!(sections, vec![1, 2, 3, 6, 7, 8, 9, 11, 12]);
        }

        #[test]
        fn add_start_custom() {
            let mut module = deserialize_file("./res/cases/v1/start_add_custom.wasm").expect("failed to deserialize");

            let sections = module.sections().iter().map(|s| s.order()).collect::<Vec<_>>();
            assert_eq!(sections, vec![1, 2, 3, 6, 7, 9, 11, 12, 0]);

            assert!(module.start_section().is_none());
            module.set_start_section(0);
            assert_eq!(module.start_section().expect("Dorder not find any start section"), 0);

            let sections = module.sections().iter().map(|s| s.order()).collect::<Vec<_>>();
            assert_eq!(sections, vec![1, 2, 3, 6, 7, 8, 9, 11, 12, 0]);
        }

        #[test]
        fn names_section_present() {
            let mut module = deserialize_file("./res/cases/v1/names.wasm").expect("failed to deserialize");

            // Before parsing
            assert!(module.names_section().is_none());
            assert!(module.names_section_mut().is_none());
            assert!(module.has_names_section());

            // After parsing
            let mut module = module.parse_names().expect("failed to parse names section");
            assert!(module.names_section().is_some());
            assert!(module.names_section_mut().is_some());
            assert!(module.has_names_section());
        }

        #[test]
        fn names_section_not_present() {
            let mut module = deserialize_file("./res/cases/v1/test.wasm").expect("failed to deserialize");

            // Before parsing
            assert!(module.names_section().is_none());
            assert!(module.names_section_mut().is_none());
            assert!(!module.has_names_section());

            // After parsing
            let mut module = module.parse_names().expect("failed to parse names section");
            assert!(module.names_section().is_none());
            assert!(module.names_section_mut().is_none());
            assert!(!module.has_names_section());
        }

        #[test]
        fn insert_sections() {
            let mut module = Module::default();

            assert!(module.insert_section(Section::Function(FunctionSection::with_entries(vec![]))).is_ok());
            // Duplicate.
            assert!(module.insert_section(Section::Function(FunctionSection::with_entries(vec![]))).is_err());

            assert!(module.insert_section(Section::Type(TypeSection::with_types(vec![]))).is_ok());
            // Duplicate.
            assert!(module.insert_section(Section::Type(TypeSection::with_types(vec![]))).is_err());

            assert!(module.insert_section(Section::Export(ExportSection::with_entries(vec![]))).is_ok());
            // Duplicate.
            assert!(module.insert_section(Section::Export(ExportSection::with_entries(vec![]))).is_err());

            assert!(module.insert_section(Section::Code(CodeSection::with_bodies(vec![]))).is_ok());
            // Duplicate.
            assert!(module.insert_section(Section::Code(CodeSection::with_bodies(vec![]))).is_err());

            // Try serialisation roundtrip to check well-orderedness.
            let serialized = serialize(module).expect("serialization to succeed");
            assert!(deserialize_buffer::<Module>(&serialized).is_ok());
        }

        #[test]
        fn serialization_roundtrip() {
            let module = deserialize_file("./res/cases/v1/test.wasm").expect("failed to deserialize");
            let module_copy = module.clone().to_bytes().expect("failed to serialize");
            let module_copy = Module::from_bytes(&module_copy).expect("failed to deserialize");
            assert_eq!(module, module_copy);
        }
    }

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