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// conn_expr/port_set.rs
// Copyright 2022 Matti Hänninen
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

use std::str;

use super::parser::{self, Parser};

pub type Port = u16;

/// Non-empty ordered set of ports
#[derive(Clone, Debug, PartialEq)]
pub struct PortSet(Vec<Port>);

impl PortSet {
  pub fn try_from_iter(iter: impl Iterator<Item = Port>) -> Option<PortSet> {
    let mut ports = vec![];
    for port in iter {
      if !ports.contains(&port) {
        ports.push(port)
      }
    }
    if ports.is_empty() {
      None
    } else {
      Some(Self(ports))
    }
  }

  pub fn as_slice(&self) -> &[Port] {
    self.0.as_slice()
  }

  pub fn into_inner(self) -> Vec<Port> {
    self.0
  }
}

impl<'a> TryFrom<parser::Pair<'a, parser::Rule>> for PortSet {
  type Error = CannotConvertToPortSetError;

  fn try_from(
    pair: parser::Pair<'a, parser::Rule>,
  ) -> Result<Self, Self::Error> {
    use parser::Rule;
    if matches!(pair.as_rule(), Rule::port_set) {
      let mut ports = vec![];
      for p in pair.into_inner() {
        match p.as_rule() {
          Rule::port => ports.push(
            p.as_str()
              .parse()
              .map_err(|_| CannotConvertToPortSetError)?,
          ),
          Rule::port_range => {
            let mut limits = p.into_inner();
            let start: Port = limits
              .next()
              .expect("grammar guarantees start port")
              .as_str()
              .parse()
              .map_err(|_| CannotConvertToPortSetError)?;
            let end = limits
              .next()
              .expect("grammar guarantees end port")
              .as_str()
              .parse()
              .map_err(|_| CannotConvertToPortSetError)?;
            if start <= end {
              ports.extend(start..=end);
            } else {
              ports.extend((end..=start).rev());
            }
          }
          _ => unreachable!("grammar guarantees port or port_range"),
        }
      }
      Ok(
        Self::try_from_iter(ports.into_iter())
          .expect("grammar guarantees at least one port"),
      )
    } else {
      Err(CannotConvertToPortSetError)
    }
  }
}

#[derive(Debug, PartialEq, thiserror::Error)]
#[error("cannot convert to port set")]
pub struct CannotConvertToPortSetError;

impl str::FromStr for PortSet {
  type Err = PortSetParseError;

  fn from_str(s: &str) -> Result<Self, Self::Err> {
    parser::ConnectionExprLanguage::parse(parser::Rule::port_set_expr, s)
      .map_err(|_| PortSetParseError)?
      .next()
      .expect("grammar guaranteed post_set_expr")
      .into_inner()
      .next()
      .expect("grammar guarantees post_set")
      .try_into()
      .map_err(|_| PortSetParseError)
  }
}

#[derive(Debug, PartialEq, thiserror::Error)]
#[error("cannot parse port set expression")]
pub struct PortSetParseError;

#[cfg(test)]
mod test {
  use super::*;

  #[test]
  fn port_set_parsing() {
    assert_eq!("1".parse(), Ok(PortSet(vec![1])));
    assert_eq!("65535".parse(), Ok(PortSet(vec![65535])));
    assert_eq!("1,2".parse(), Ok(PortSet(vec![1, 2])));
    assert_eq!("1-3".parse(), Ok(PortSet(vec![1, 2, 3])));
    assert_eq!("3-1".parse(), Ok(PortSet(vec![3, 2, 1])));
    assert_eq!("1,1-2,5,2-4".parse(), Ok(PortSet(vec![1, 2, 5, 3, 4])));
    assert_eq!("".parse::<PortSet>(), Err(PortSetParseError));
    assert_eq!(" 1".parse::<PortSet>(), Err(PortSetParseError));
    assert_eq!("1 ".parse::<PortSet>(), Err(PortSetParseError));
    assert_eq!(",".parse::<PortSet>(), Err(PortSetParseError));
    assert_eq!(",1".parse::<PortSet>(), Err(PortSetParseError));
    assert_eq!("1,".parse::<PortSet>(), Err(PortSetParseError));
    assert_eq!("-1".parse::<PortSet>(), Err(PortSetParseError));
    assert_eq!("1-".parse::<PortSet>(), Err(PortSetParseError));
    assert_eq!("1,,2".parse::<PortSet>(), Err(PortSetParseError));
    assert_eq!("1--2".parse::<PortSet>(), Err(PortSetParseError));
    assert_eq!("1-2-3".parse::<PortSet>(), Err(PortSetParseError));
    assert_eq!("65536".parse::<PortSet>(), Err(PortSetParseError));
  }
}