bunbun/src/config.rs

use crate::BunBunError;
use dirs::{config_dir, home_dir};
use log::{debug, info, trace};
use serde::{
  de::{Deserializer, Visitor},
  Deserialize, Serialize, Serializer,
};
use std::collections::HashMap;
use std::fmt;
use std::fs::{File, OpenOptions};
use std::io::{Read, Write};
use std::path::PathBuf;

const CONFIG_FILENAME: &str = "bunbun.yaml";
const DEFAULT_CONFIG: &[u8] = include_bytes!("../bunbun.default.yaml");

#[derive(Deserialize, Debug, PartialEq)]
pub struct Config {
  pub bind_address: String,
  pub public_address: String,
  pub default_route: Option<String>,
  pub groups: Vec<RouteGroup>,
}

#[derive(Deserialize, Serialize, Debug, PartialEq, Clone)]
pub struct RouteGroup {
  pub name: String,
  pub description: Option<String>,
  pub routes: HashMap<String, Route>,
}

#[derive(Debug, PartialEq, Clone)]
pub enum Route {
  External(String),
  Path(String),
}

/// Serialization of the Route enum needs to be transparent, but since the
/// `#[serde(transparent)]` macro isn't available on enums, so we need to
/// implement it manually.
impl Serialize for Route {
  fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
  where
    S: Serializer,
  {
    match self {
      Self::External(s) => serializer.serialize_str(s),
      Self::Path(s) => serializer.serialize_str(s),
    }
  }
}

/// Deserialization of the route string into the enum requires us to figure out
/// whether or not the string is valid to run as an executable or not. To
/// determine this, we simply check if it exists on disk or assume that it's a
/// web path. This incurs a disk check operation, but since users shouldn't be
/// updating the config that frequently, it should be fine.
impl<'de> Deserialize<'de> for Route {
  fn deserialize<D>(deserializer: D) -> Result<Route, D::Error>
  where
    D: Deserializer<'de>,
  {
    struct RouteVisitor;
    impl<'de> Visitor<'de> for RouteVisitor {
      type Value = Route;

      fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        formatter.write_str("string")
      }

      fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
      where
        E: serde::de::Error,
      {
        // Return early if it's a path, don't go through URL parsing
        if std::path::Path::new(value).exists() {
          debug!("Parsed {} as a valid local path.", value);
          Ok(Route::Path(value.into()))
        } else {
          debug!("{} does not exist on disk, assuming web path.", value);
          Ok(Route::External(value.into()))
        }
      }
    }

    deserializer.deserialize_str(RouteVisitor)
  }
}

impl std::fmt::Display for Route {
  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
    match self {
      Self::External(s) => write!(f, "raw ({})", s),
      Self::Path(s) => write!(f, "file ({})", s),
    }
  }
}

pub struct ConfigData {
  pub path: PathBuf,
  pub file: File,
}

/// If a provided config path isn't found, this function checks known good
/// locations for a place to write a config file to. In order, it checks the
/// system-wide config location (`/etc/`, in Linux), followed by the config
/// folder, followed by the user's home folder.
pub fn get_config_data() -> Result<ConfigData, BunBunError> {
  // Locations to check, with highest priority first
  let locations: Vec<_> = {
    let mut folders = vec![PathBuf::from("/etc/")];

    // Config folder
    if let Some(folder) = config_dir() { folders.push(folder) }

    // Home folder
    if let Some(folder) = home_dir() { folders.push(folder) }

    folders
      .iter_mut()
      .for_each(|folder| folder.push(CONFIG_FILENAME));

    folders
  };

  debug!("Checking locations for config file: {:?}", &locations);

  for location in &locations {
    let file = OpenOptions::new().read(true).open(location.clone());
    match file {
      Ok(file) => {
        debug!("Found file at {:?}.", location);
        return Ok(ConfigData {
          path: location.clone(),
          file,
        })
      }
      Err(e) => debug!(
        "Tried to read '{:?}' but failed due to error: {}",
        location,
        e
      ),
    }
  }

  debug!("Failed to find any config. Now trying to find first writable path");

  // If we got here, we failed to read any file paths, meaning no config exists
  // yet. In that case, try to return the first location that we can write to,
  // after writing the default config
  for location in locations {
    let file = OpenOptions::new()
      .write(true)
      .create_new(true)
      .open(location.clone());
    match file {
      Ok(mut file) => {
        info!("Creating new config file at {:?}.", location);
        file.write_all(DEFAULT_CONFIG)?;

        let file = OpenOptions::new().read(true).open(location.clone())?;
        return Ok(ConfigData {
          path: location,
          file,
        });
      }
      Err(e) => debug!(
        "Tried to open a new file at '{:?}' but failed due to error: {}",
        location,
        e
      ),
    }
  }

  Err(BunBunError::NoValidConfigPath)
}

/// Assumes that the user knows what they're talking about and will only try
/// to load the config at the given path.
pub fn load_custom_path_config(
  path: impl Into<PathBuf>,
) -> Result<ConfigData, BunBunError> {
  let path = path.into();
  Ok(ConfigData {
    file: OpenOptions::new().read(true).open(&path)?,
    path,
  })
}

pub fn read_config(mut config_file: File) -> Result<Config, BunBunError> {
  trace!("Loading config file...");
  let mut config_data = String::new();
  config_file.read_to_string(&mut config_data)?;
  // Reading from memory is faster than reading directly from a reader for some
  // reason; see https://github.com/serde-rs/json/issues/160
  Ok(serde_yaml::from_str(&config_data)?)
}

#[cfg(test)]
mod route {
  use super::*;
  use serde_yaml::{from_str, to_string};
  use tempfile::NamedTempFile;

  #[test]
  fn deserialize_relative_path() {
    let tmpfile = NamedTempFile::new_in(".").unwrap();
    let path = format!("{}", tmpfile.path().display());
    let path = path.get(path.rfind(".").unwrap()..).unwrap();
    let path = std::path::Path::new(path);
    assert!(path.is_relative());
    let path = path.to_str().unwrap();
    assert_eq!(from_str::<Route>(path).unwrap(), Route::Path(path.into()));
  }

  #[test]
  fn deserialize_absolute_path() {
    let tmpfile = NamedTempFile::new().unwrap();
    let path = format!("{}", tmpfile.path().display());
    assert!(tmpfile.path().is_absolute());
    assert_eq!(from_str::<Route>(&path).unwrap(), Route::Path(path));
  }

  #[test]
  fn deserialize_http_path() {
    assert_eq!(
      from_str::<Route>("http://google.com").unwrap(),
      Route::External("http://google.com".into())
    );
  }

  #[test]
  fn deserialize_https_path() {
    assert_eq!(
      from_str::<Route>("https://google.com").unwrap(),
      Route::External("https://google.com".into())
    );
  }

  #[test]
  fn serialize() {
    assert_eq!(
      &to_string(&Route::External("hello world".into())).unwrap(),
      "---\nhello world"
    );
    assert_eq!(
      &to_string(&Route::Path("hello world".into())).unwrap(),
      "---\nhello world"
    );
  }
}