1 files changed, 252 insertions, 0 deletions
diff --git a/src/common/query.rs b/src/common/query.rs
new file mode 100644
index 0000000..00d79b2
--- /dev/null
+++ b/src/common/query.rs
@@ -0,0 +1,252 @@
+use crate::common::db::Database;
+use crate::common::expr::Expr;
+use crate::common::ip;
+use std::fmt;
+
+#[derive(Debug)]
+pub enum Error {
+    Empty,
+    Invalid,
+    IP(ip::Error),
+    ExpectedArray(Expr),
+    ExpectedBlob(Expr),
+    InvalidArgsCount {
+        cmd: String,
+        expected: usize,
+        actual: usize,
+    },
+}
+
+#[derive(Debug)]
+pub enum Query {
+    Children { ip_block: ip::Block },
+    Del { ip_block: ip::Block },
+    Echo { msg: Vec<u8> },
+    Exists { ip_block: ip::Block },
+    Get { ip_block: ip::Block },
+    Info { ip_block: ip::Block },
+    Parent { ip_block: ip::Block },
+    Set { ip_block: ip::Block, value: Expr },
+}
+
+impl Query {
+    pub fn from_expr(expr: Expr) -> Result<Self, Error> {
+        let mut xs = if let Expr::Array(xs) = expr {
+            xs
+        } else {
+            return Err(Error::ExpectedArray(expr));
+        };
+
+        if xs.is_empty() {
+            return Err(Error::Empty);
+        }
+        let cmd_expr = xs.remove(0);
+        let cmd = if let Expr::Blob(cmd) = cmd_expr {
+            cmd
+        } else {
+            return Err(Error::ExpectedBlob(cmd_expr));
+        };
+
+        match &*cmd {
+            b"ECHO" => build_echo(xs),         // ECHO str
+            b"SET" => build_set(xs),           // SET ::/32 Expr
+            b"GET" => build_get(xs),           // GET ::/32
+            b"DEL" => build_del(xs),           // DEL ::/32
+            b"EXISTS" => build_exists(xs),     // EXISTS ::/32
+            b"INFO" => build_info(xs),         // EXISTS ::/32
+            b"PARENT" => build_parent(xs),     // SUP ::/32
+            b"CHILDREN" => build_children(xs), // SUB ::/32
+            _ => Err(Error::Invalid),
+        }
+    }
+
+    pub fn exec(&self, db: &mut Database) -> Expr {
+        match self {
+            Self::Echo { msg } => Expr::Blob(msg.clone()),
+            Self::Set { ip_block, value: _ } => {
+                db.set(*ip_block, std::collections::HashMap::new());
+                Expr::Blob(b"OK".to_vec())
+            }
+            Self::Get { ip_block } => db.get(ip_block).map(|x| x.into()).unwrap_or(Expr::Null),
+            Self::Del { ip_block } => db
+                .del(ip_block)
+                .map_or(Expr::Null, |_| Expr::Blob(b"OK".to_vec())),
+            Self::Exists { ip_block } => Expr::Bool(db.exists(ip_block)),
+            Self::Info { ip_block } => {
+                let info: Vec<(&str, String)> = db.info(ip_block).into();
+                info.into()
+            }
+            Self::Parent { ip_block } => {
+                db.parent(ip_block).map(|x| x.into()).unwrap_or(Expr::Null)
+            }
+            Self::Children { ip_block } => db.children(ip_block).into(),
+        }
+    }
+}
+
+// Display
+
+impl fmt::Display for Query {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let res = match self {
+            Query::Set { ip_block, value } => {
+                format!("SET {} {}", ip_block, value)
+            }
+            Query::Get { ip_block } => {
+                format!("GET {}", ip_block)
+            }
+            Query::Echo { msg } => {
+                format!("ECHO {:?}", String::from_utf8_lossy(msg).into_owned())
+            }
+            Query::Del { ip_block } => {
+                format!("DEL {}", ip_block)
+            }
+            Query::Exists { ip_block } => {
+                format!("EXISTS {}", ip_block)
+            }
+            Query::Info { ip_block } => {
+                format!("INFO {}", ip_block)
+            }
+            Query::Parent { ip_block } => {
+                format!("PARENT {}", ip_block)
+            }
+            Query::Children { ip_block } => {
+                format!("CHILDREN {}", ip_block)
+            }
+        };
+
+        write!(f, "{}", res)
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let res = match self {
+            Error::Empty => "Received an empty query.".to_string(),
+            Error::ExpectedArray(got) => format!("Expected an ARRAY, got: {:?}.", got),
+            Error::ExpectedBlob(got) => format!("Expected a BLOB, got: {:?}.", got),
+            Error::IP(e) => format!("IP error: {e:?}"),
+            Error::Invalid => "Received an invalid query.".to_string(),
+            Error::InvalidArgsCount {
+                cmd,
+                expected,
+                actual,
+            } => format!(
+                "Invalid number of arguments for {:?}. Expected {} but got {}.",
+                cmd, expected, actual
+            ),
+        };
+
+        write!(f, "{}", res)
+    }
+}
+
+// Builders
+
+fn build_echo(mut args: Vec<Expr>) -> Result<Query, Error> {
+    count_args("ECHO", &args, 1)?;
+
+    let expr = args.remove(0);
+    let msg = if let Expr::Blob(k) = expr {
+        k
+    } else {
+        return Err(Error::ExpectedBlob(expr));
+    };
+    Ok(Query::Echo { msg })
+}
+
+fn build_get(mut args: Vec<Expr>) -> Result<Query, Error> {
+    count_args("GET", &args, 1)?;
+
+    let expr = args.remove(0);
+    let ip_block = if let Expr::Blob(ref addr) = expr {
+        ip::Block::from_bytestring(addr).map_err(Error::IP)?
+    } else {
+        return Err(Error::ExpectedBlob(expr));
+    };
+    Ok(Query::Get { ip_block })
+}
+fn build_set(mut args: Vec<Expr>) -> Result<Query, Error> {
+    count_args("SET", &args, 2)?;
+
+    let expr = args.remove(0);
+    let ip_block = if let Expr::Blob(ref addr) = expr {
+        ip::Block::from_bytestring(addr).map_err(Error::IP)?
+    } else {
+        return Err(Error::ExpectedBlob(expr));
+    };
+    Ok(Query::Set {
+        ip_block,
+        value: args.remove(0),
+    })
+}
+fn build_del(mut args: Vec<Expr>) -> Result<Query, Error> {
+    count_args("DEL", &args, 1)?;
+
+    let expr = args.remove(0);
+    let ip_block = if let Expr::Blob(ref addr) = expr {
+        ip::Block::from_bytestring(addr).map_err(Error::IP)?
+    } else {
+        return Err(Error::ExpectedBlob(expr));
+    };
+    Ok(Query::Del { ip_block })
+}
+fn build_exists(mut args: Vec<Expr>) -> Result<Query, Error> {
+    count_args("EXISTS", &args, 1)?;
+
+    let expr = args.remove(0);
+    let ip_block = if let Expr::Blob(ref addr) = expr {
+        ip::Block::from_bytestring(addr).map_err(Error::IP)?
+    } else {
+        return Err(Error::ExpectedBlob(expr));
+    };
+    Ok(Query::Exists { ip_block })
+}
+fn build_info(mut args: Vec<Expr>) -> Result<Query, Error> {
+    count_args("INFO", &args, 1)?;
+
+    let expr = args.remove(0);
+    let ip_block = if let Expr::Blob(ref addr) = expr {
+        ip::Block::from_bytestring(addr).map_err(Error::IP)?
+    } else {
+        return Err(Error::ExpectedBlob(expr));
+    };
+    Ok(Query::Info { ip_block })
+}
+fn build_parent(mut args: Vec<Expr>) -> Result<Query, Error> {
+    count_args("PARENT", &args, 1)?;
+
+    let expr = args.remove(0);
+    let ip_block = if let Expr::Blob(ref addr) = expr {
+        ip::Block::from_bytestring(addr).map_err(Error::IP)?
+    } else {
+        return Err(Error::ExpectedBlob(expr));
+    };
+    Ok(Query::Parent { ip_block })
+}
+fn build_children(mut args: Vec<Expr>) -> Result<Query, Error> {
+    count_args("CHILDREN", &args, 1)?;
+
+    let expr = args.remove(0);
+    let ip_block = if let Expr::Blob(ref addr) = expr {
+        ip::Block::from_bytestring(addr).map_err(Error::IP)?
+    } else {
+        return Err(Error::ExpectedBlob(expr));
+    };
+    Ok(Query::Children { ip_block })
+}
+
+// Helpers
+
+fn count_args<T>(cmd: &str, args: &Vec<T>, expected_count: usize) -> Result<(), Error> {
+    let args_count = args.len();
+    if args_count != expected_count {
+        return Err(Error::InvalidArgsCount {
+            cmd: cmd.to_string(),
+            expected: expected_count,
+            actual: args_count,
+        });
+    }
+
+    Ok(())
+}