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use {ParamType, Error, ErrorKind};

/// Used to convert param type represented as a string to rust structure.
pub struct Reader;

impl Reader {
	/// Converts string to param type.
	pub fn read(name: &str) -> Result<ParamType, Error> {
		// check if it is a fixed or dynamic array.
		if let Some(']') = name.chars().last() {
			// take number part
			let num: String = name.chars()
				.rev()
				.skip(1)
				.take_while(|c| *c != '[')
				.collect::<String>()
				.chars()
				.rev()
				.collect();

			let count = name.chars().count();
			if num.is_empty() {
				// we already know it's a dynamic array!
				let subtype = try!(Reader::read(&name[..count - 2]));
				return Ok(ParamType::Array(Box::new(subtype)));
			} else {
				// it's a fixed array.
				let len = try!(usize::from_str_radix(&num, 10));
				let subtype = try!(Reader::read(&name[..count - num.len() - 2]));
				return Ok(ParamType::FixedArray(Box::new(subtype), len));
			}
		}

		let result = match name {
			"address" => ParamType::Address,
			"bytes" => ParamType::Bytes,
			"bool" => ParamType::Bool,
			"string" => ParamType::String,
			"int" => ParamType::Int(256),
			"uint" => ParamType::Uint(256),
			s if s.starts_with("int") => {
				let len = try!(usize::from_str_radix(&s[3..], 10));
				ParamType::Int(len)
			},
			s if s.starts_with("uint") => {
				let len = try!(usize::from_str_radix(&s[4..], 10));
				ParamType::Uint(len)
			},
			s if s.starts_with("bytes") => {
				let len = try!(usize::from_str_radix(&s[5..], 10));
				ParamType::FixedBytes(len)
			},
			_ => {
				return Err(ErrorKind::InvalidName(name.to_owned()).into());
			}
		};

		Ok(result)
	}
}

#[cfg(test)]
mod tests {
	use ParamType;
	use super::Reader;

	#[test]
	fn test_read_param() {
		assert_eq!(Reader::read("address").unwrap(), ParamType::Address);
		assert_eq!(Reader::read("bytes").unwrap(), ParamType::Bytes);
		assert_eq!(Reader::read("bytes32").unwrap(), ParamType::FixedBytes(32));
		assert_eq!(Reader::read("bool").unwrap(), ParamType::Bool);
		assert_eq!(Reader::read("string").unwrap(), ParamType::String);
		assert_eq!(Reader::read("int").unwrap(), ParamType::Int(256));
		assert_eq!(Reader::read("uint").unwrap(), ParamType::Uint(256));
		assert_eq!(Reader::read("int32").unwrap(), ParamType::Int(32));
		assert_eq!(Reader::read("uint32").unwrap(), ParamType::Uint(32));
	}

	#[test]
	fn test_read_array_param() {
		assert_eq!(Reader::read("address[]").unwrap(), ParamType::Array(Box::new(ParamType::Address)));
		assert_eq!(Reader::read("uint[]").unwrap(), ParamType::Array(Box::new(ParamType::Uint(256))));
		assert_eq!(Reader::read("bytes[]").unwrap(), ParamType::Array(Box::new(ParamType::Bytes)));
		assert_eq!(Reader::read("bool[][]").unwrap(), ParamType::Array(Box::new(ParamType::Array(Box::new(ParamType::Bool)))));
	}

	#[test]
	fn test_read_fixed_array_param() {
		assert_eq!(Reader::read("address[2]").unwrap(), ParamType::FixedArray(Box::new(ParamType::Address), 2));
		assert_eq!(Reader::read("bool[17]").unwrap(), ParamType::FixedArray(Box::new(ParamType::Bool), 17));
		assert_eq!(Reader::read("bytes[45][3]").unwrap(), ParamType::FixedArray(Box::new(ParamType::FixedArray(Box::new(ParamType::Bytes), 45)), 3));
	}

	#[test]
	fn test_read_mixed_arrays() {
		assert_eq!(Reader::read("bool[][3]").unwrap(), ParamType::FixedArray(Box::new(ParamType::Array(Box::new(ParamType::Bool))), 3));
		assert_eq!(Reader::read("bool[3][]").unwrap(), ParamType::Array(Box::new(ParamType::FixedArray(Box::new(ParamType::Bool), 3))));
	}
}