1 files changed, 364 insertions, 0 deletions
diff --git a/src/common/expr.rs b/src/common/expr.rs
new file mode 100644
index 0000000..0a7880b
--- /dev/null
+++ b/src/common/expr.rs
@@ -0,0 +1,364 @@
+#![allow(clippy::from_over_into)]
+use crate::common::ip;
+use std::convert::Into;
+use std::fmt;
+use std::io::BufRead;
+use std::io::BufReader;
+use std::io::Read;
+use std::net::TcpStream;
+use std::num::ParseIntError;
+
+#[derive(Debug, Clone, Hash)]
+pub enum Expr {
+    Array(Vec<Expr>),
+    Blob(Vec<u8>),
+    Bool(bool),
+    Error { code: Vec<u8>, msg: Vec<u8> },
+    Line(Vec<u8>),
+    Number(u128),
+    Table(Vec<(Expr, Expr)>),
+    Null,
+}
+
+#[derive(Debug)]
+pub enum Error {
+    ConnectionClosed,
+    InvalidChar(u8),
+    NotANumber(Vec<u8>),
+    InvalidTag(u8),
+    InvalidHeaderSize,
+    NotEnoughBytes,
+    ExpectedLF(u8),
+}
+
+impl Expr {
+    pub fn from_bytes(reader: &mut BufReader<&TcpStream>) -> Result<Self, Error> {
+        let mut header = vec![];
+
+        reader
+            .read_until(b'\n', &mut header)
+            .map_err(|_| Error::ConnectionClosed)?;
+
+        if header.is_empty() {
+            return Err(Error::ConnectionClosed);
+        }
+
+        match header[0] {
+            b'!' => parse_error(header, reader),
+            b'#' => parse_bool(header, reader),
+            b'$' => parse_blob(header, reader),
+            b'*' => parse_array(header, reader),
+            b'+' => parse_line(header, reader),
+            b':' => parse_number(header, reader),
+            b'_' => Ok(Expr::Null),
+            _ => Err(Error::InvalidTag(header[0])),
+        }
+    }
+
+    pub fn from_query(query: &str) -> Self {
+        let args = query
+            .split(' ')
+            .map(|x| Expr::Blob(x.as_bytes().to_vec()))
+            .collect();
+        Expr::Array(args)
+    }
+
+    pub fn encode(&self) -> Vec<u8> {
+        match self {
+            Expr::Array(arr) => encode_array(arr.clone()),
+            Expr::Blob(blob) => encode_blob(blob.to_vec()),
+            Expr::Bool(val) => encode_bool(*val),
+            Expr::Error { code, msg } => encode_error(code.to_vec(), msg.to_vec()),
+            Expr::Line(line) => encode_line(line.to_vec()),
+            Expr::Number(number) => encode_number(*number),
+            Expr::Null => b"_\n".to_vec(),
+            Expr::Table(table) => encode_table(table),
+        }
+    }
+}
+
+// Display
+
+impl fmt::Display for Expr {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let res = match self {
+            Expr::Array(array) => {
+                format!(
+                    "[{}]",
+                    array
+                        .iter()
+                        .map(|x| x.to_string())
+                        .collect::<Vec<String>>()
+                        .join(", ")
+                )
+            }
+            Expr::Bool(value) => {
+                if *value {
+                    "true".to_string()
+                } else {
+                    "false".to_string()
+                }
+            }
+            Expr::Blob(blob) => format!("{:?}", String::from_utf8_lossy(blob).into_owned()),
+            Expr::Number(number) => format!("{:?}", number),
+            Expr::Error { code, msg } => format!(
+                "!{} {:?}",
+                String::from_utf8_lossy(code).into_owned(),
+                String::from_utf8_lossy(msg).into_owned()
+            ),
+            Expr::Line(line) => format!("{:?}", String::from_utf8_lossy(line).into_owned()),
+            Expr::Null => "(null)".to_string(),
+            Expr::Table(table) => {
+                format!(
+                    "[{}]",
+                    table
+                        .iter()
+                        .map(|(k, v)| format!("{}: {}", k, v))
+                        .collect::<Vec<String>>()
+                        .join(", ")
+                )
+            }
+        };
+
+        write!(f, "{}", res)
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let res = match self {
+            Error::ConnectionClosed => "Connection closed.".to_string(),
+            Error::InvalidChar(got) => format!("Invalid char: {:?}.", *got as char),
+            Error::NotANumber(got) => format!("Not a number: {:?}.", got),
+            Error::ExpectedLF(got) => format!("Expected LF, got: {:?}.", *got as char),
+            Error::InvalidHeaderSize => "Invalid header size.".to_string(),
+            Error::InvalidTag(got) => format!("Invalid tag {:?}.", *got as char),
+            Error::NotEnoughBytes => "Not enough bytes.".to_string(),
+        };
+
+        write!(f, "{}", res)
+    }
+}
+
+// Encoders
+
+fn encode_array(array: Vec<Expr>) -> Vec<u8> {
+    let mut res = array.len().to_string().as_bytes().to_vec();
+
+    res.insert(0, b'*');
+    res.push(b'\n');
+
+    for expr in array {
+        res.append(&mut expr.encode());
+    }
+
+    res
+}
+fn encode_bool(val: bool) -> Vec<u8> {
+    if val {
+        b"#t\n".to_vec()
+    } else {
+        b"#f\n".to_vec()
+    }
+}
+fn encode_blob(mut blob: Vec<u8>) -> Vec<u8> {
+    let mut res = blob.len().to_string().as_bytes().to_vec();
+
+    res.insert(0, b'$');
+    res.push(b'\n');
+    res.append(&mut blob);
+    res.push(b'\n');
+
+    res
+}
+
+fn encode_line(mut line: Vec<u8>) -> Vec<u8> {
+    line.insert(0, b'+');
+    line.push(b'\n');
+
+    line
+}
+
+fn encode_number(number: u128) -> Vec<u8> {
+    let mut res = vec![b':'];
+    res.append(&mut number.to_string().as_bytes().to_vec());
+    res.push(b'\n');
+
+    res
+}
+
+fn encode_error(mut code: Vec<u8>, mut msg: Vec<u8>) -> Vec<u8> {
+    let mut res = (code.len() + msg.len()).to_string().as_bytes().to_vec();
+
+    res.insert(0, b'!');
+    res.push(b'\n');
+    res.append(&mut code);
+    res.push(b' ');
+    res.append(&mut msg);
+    res.push(b'\n');
+
+    res
+}
+
+fn encode_table(table: &Vec<(Expr, Expr)>) -> Vec<u8> {
+    let mut res = table.len().to_string().as_bytes().to_vec();
+
+    res.insert(0, b'%');
+    res.push(b'\n');
+
+    for (key, val) in table {
+        res.append(&mut key.encode());
+        res.append(&mut val.encode());
+    }
+
+    res
+}
+
+// Parsers
+
+fn parse_line(header: Vec<u8>, _reader: &mut BufReader<&TcpStream>) -> Result<Expr, Error> {
+    if header.len() < 2 {
+        return Err(Error::NotEnoughBytes);
+    }
+
+    Ok(Expr::Line(header[1..header.len() - 1].to_vec()))
+}
+
+fn parse_number(header: Vec<u8>, _reader: &mut BufReader<&TcpStream>) -> Result<Expr, Error> {
+    if header.len() < 2 {
+        return Err(Error::NotEnoughBytes);
+    }
+
+    let digits = &header[1..header.len() - 1];
+
+    Ok(Expr::Number(
+        as_u128(digits).map_err(|_| Error::NotANumber(digits.to_vec()))?,
+    ))
+}
+
+fn parse_blob(header: Vec<u8>, reader: &mut BufReader<&TcpStream>) -> Result<Expr, Error> {
+    let size = as_usize(&header[1..header.len() - 1]).map_err(|_| Error::InvalidHeaderSize)?;
+
+    let mut body = vec![0u8; size];
+    reader
+        .read_exact(&mut body)
+        .map_err(|_| Error::NotEnoughBytes)?;
+
+    skip_lf(reader)?;
+
+    Ok(Expr::Blob(body))
+}
+
+fn parse_error(header: Vec<u8>, reader: &mut BufReader<&TcpStream>) -> Result<Expr, Error> {
+    let size = as_usize(&header[1..header.len() - 1]).map_err(|_| Error::InvalidHeaderSize)?;
+
+    let mut body = vec![0u8; size];
+    reader
+        .read_exact(&mut body)
+        .map_err(|_| Error::NotEnoughBytes)?;
+
+    skip_lf(reader)?;
+
+    let parts: Vec<&[u8]> = body.splitn(2, |x| *x == b' ').collect();
+    if parts.len() < 2 {
+        return Err(Error::NotEnoughBytes);
+    }
+
+    Ok(Expr::Error {
+        code: parts[0].to_vec(),
+        msg: parts[1].to_vec(),
+    })
+}
+
+fn parse_array(header: Vec<u8>, reader: &mut BufReader<&TcpStream>) -> Result<Expr, Error> {
+    let size = as_usize(&header[1..header.len() - 1]).map_err(|_| Error::InvalidHeaderSize)?;
+
+    let body: Vec<Expr> = (0..size)
+        .map(|_| Expr::from_bytes(reader))
+        .collect::<Result<Vec<Expr>, _>>()?;
+
+    Ok(Expr::Array(body))
+}
+
+fn parse_bool(header: Vec<u8>, _reader: &mut BufReader<&TcpStream>) -> Result<Expr, Error> {
+    if header.len() < 2 {
+        return Err(Error::NotEnoughBytes);
+    }
+
+    match header[1] {
+        b't' => Ok(Expr::Bool(true)),
+        b'f' => Ok(Expr::Bool(false)),
+        other => Err(Error::InvalidChar(other)),
+    }
+}
+
+// Into
+
+impl Into<Expr> for ip::Block {
+    fn into(self) -> Expr {
+        Expr::Line(self.into())
+    }
+}
+
+impl Into<Expr> for &ip::Block {
+    fn into(self) -> Expr {
+        Expr::Line(self.into())
+    }
+}
+
+impl Into<Expr> for &str {
+    fn into(self) -> Expr {
+        Expr::Blob(self.into())
+    }
+}
+
+impl Into<Expr> for String {
+    fn into(self) -> Expr {
+        Expr::Blob(self.into())
+    }
+}
+
+impl Into<Expr> for u8 {
+    fn into(self) -> Expr {
+        Expr::Number(self as u128)
+    }
+}
+
+impl Into<Expr> for Vec<(&str, String)> {
+    fn into(self) -> Expr {
+        Expr::Table(
+            self.into_iter()
+                .map(|(x, y)| (x.into(), y.into()))
+                .collect(),
+        )
+    }
+}
+
+impl<T: Into<Expr>> Into<Expr> for Vec<T> {
+    fn into(self) -> Expr {
+        Expr::Array(self.into_iter().map(|x| x.into()).collect())
+    }
+}
+
+// Helpers
+
+fn skip_lf(reader: &mut BufReader<&TcpStream>) -> Result<(), Error> {
+    let mut lf = vec![0u8; 1];
+
+    reader
+        .read_exact(&mut lf)
+        .map_err(|_| Error::NotEnoughBytes)?;
+
+    if lf != vec![b'\n'] {
+        return Err(Error::ExpectedLF(lf[0]));
+    }
+    Ok(())
+}
+
+fn as_usize(array: &[u8]) -> Result<usize, ParseIntError> {
+    std::str::from_utf8(array).unwrap().parse::<usize>()
+}
+
+fn as_u128(array: &[u8]) -> Result<u128, ParseIntError> {
+    std::str::from_utf8(array).unwrap().parse::<u128>()
+}