jj/src/config.rs

// Copyright 2022 The Jujutsu Authors
//
// 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
//
// https://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::borrow::Cow;
use std::collections::HashSet;
use std::path::{Path, PathBuf};
use std::process::Command;
use std::{env, fmt};

use config::Source;
use itertools::Itertools;
use thiserror::Error;

#[derive(Error, Debug)]
pub enum ConfigError {
    #[error(transparent)]
    ConfigReadError(#[from] config::ConfigError),
    #[error("Both {0} and {1} exist. Please consolidate your configs in one of them.")]
    AmbiguousSource(PathBuf, PathBuf),
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub enum ConfigSource {
    Default,
    Env,
    // TODO: Track explicit file paths, especially for when user config is a dir.
    User,
    Repo,
    CommandArg,
}

#[derive(Clone, Debug, PartialEq)]
pub struct AnnotatedValue {
    pub path: Vec<String>,
    pub value: config::Value,
    pub source: ConfigSource,
    pub is_overridden: bool,
}

/// Set of configs which can be merged as needed.
///
/// Sources from the lowest precedence:
/// 1. Default
/// 2. Base environment variables
/// 3. User config `~/.jjconfig.toml` or `$JJ_CONFIG`
/// 4. Repo config `.jj/repo/config.toml`
/// 5. TODO: Workspace config `.jj/config.toml`
/// 6. Override environment variables
/// 7. Command-line arguments `--config-toml`
#[derive(Clone, Debug)]
pub struct LayeredConfigs {
    default: config::Config,
    env_base: config::Config,
    user: Option<config::Config>,
    repo: Option<config::Config>,
    env_overrides: config::Config,
    arg_overrides: Option<config::Config>,
}

impl LayeredConfigs {
    /// Initializes configs with infallible sources.
    pub fn from_environment() -> Self {
        LayeredConfigs {
            default: default_config(),
            env_base: env_base(),
            user: None,
            repo: None,
            env_overrides: env_overrides(),
            arg_overrides: None,
        }
    }

    pub fn read_user_config(&mut self) -> Result<(), ConfigError> {
        self.user = config_path()?
            .map(|path| read_config_path(&path))
            .transpose()?;
        Ok(())
    }

    pub fn read_repo_config(&mut self, repo_path: &Path) -> Result<(), ConfigError> {
        self.repo = Some(read_config_file(&repo_path.join("config.toml"))?);
        Ok(())
    }

    pub fn parse_config_args(&mut self, toml_strs: &[String]) -> Result<(), ConfigError> {
        let config = toml_strs
            .iter()
            .fold(config::Config::builder(), |builder, s| {
                builder.add_source(config::File::from_str(s, config::FileFormat::Toml))
            })
            .build()?;
        self.arg_overrides = Some(config);
        Ok(())
    }

    /// Creates new merged config.
    pub fn merge(&self) -> config::Config {
        self.sources()
            .into_iter()
            .map(|(_, config)| config)
            .fold(config::Config::builder(), |builder, source| {
                builder.add_source(source.clone())
            })
            .build()
            .expect("loaded configs should be merged without error")
    }

    fn sources(&self) -> Vec<(ConfigSource, &config::Config)> {
        let config_sources = [
            (ConfigSource::Default, Some(&self.default)),
            (ConfigSource::Env, Some(&self.env_base)),
            (ConfigSource::User, self.user.as_ref()),
            (ConfigSource::Repo, self.repo.as_ref()),
            (ConfigSource::Env, Some(&self.env_overrides)),
            (ConfigSource::CommandArg, self.arg_overrides.as_ref()),
        ];
        config_sources
            .into_iter()
            .filter_map(|(source, config)| config.map(|c| (source, c)))
            .collect_vec()
    }

    pub fn resolved_config_values(
        &self,
        filter_prefix: &[&str],
    ) -> Result<Vec<AnnotatedValue>, ConfigError> {
        // Collect annotated values from each config.
        let mut config_vals = vec![];

        let prefix_key = match filter_prefix {
            &[] => None,
            _ => Some(filter_prefix.join(".")),
        };
        for (source, config) in self.sources() {
            let top_value = match prefix_key {
                Some(ref key) => match config.get(key) {
                    Err(config::ConfigError::NotFound { .. }) => continue,
                    val => val?,
                },
                None => config.collect()?.into(),
            };
            let mut config_stack: Vec<(Vec<&str>, &config::Value)> =
                vec![(filter_prefix.to_vec(), &top_value)];
            while let Some((path, value)) = config_stack.pop() {
                match &value.kind {
                    config::ValueKind::Table(table) => {
                        // TODO: Remove sorting when config crate maintains deterministic ordering.
                        for (k, v) in table.iter().sorted_by_key(|(k, _)| *k).rev() {
                            let mut key_path = path.to_vec();
                            key_path.push(k);
                            config_stack.push((key_path, v));
                        }
                    }
                    _ => {
                        config_vals.push(AnnotatedValue {
                            path: path.iter().map(|&s| s.to_owned()).collect_vec(),
                            value: value.to_owned(),
                            source: source.to_owned(),
                            // Note: Value updated below.
                            is_overridden: false,
                        });
                    }
                }
            }
        }

        // Walk through config values in reverse order and mark each overridden value as
        // overridden.
        let mut keys_found = HashSet::new();
        for val in config_vals.iter_mut().rev() {
            val.is_overridden = !keys_found.insert(&val.path);
        }

        Ok(config_vals)
    }
}

pub fn config_path() -> Result<Option<PathBuf>, ConfigError> {
    if let Ok(config_path) = env::var("JJ_CONFIG") {
        // TODO: We should probably support colon-separated (std::env::split_paths)
        // paths here
        Ok(Some(PathBuf::from(config_path)))
    } else {
        // TODO: Should we drop the final `/config.toml` and read all files in the
        // directory?
        let platform_specific_config_path = dirs::config_dir()
            .map(|config_dir| config_dir.join("jj").join("config.toml"))
            .filter(|path| path.exists());
        let home_config_path = dirs::home_dir()
            .map(|home_dir| home_dir.join(".jjconfig.toml"))
            .filter(|path| path.exists());
        match (&platform_specific_config_path, &home_config_path) {
            (Some(xdg_config_path), Some(home_config_path)) => Err(ConfigError::AmbiguousSource(
                xdg_config_path.clone(),
                home_config_path.clone(),
            )),
            _ => Ok(platform_specific_config_path.or(home_config_path)),
        }
    }
}

/// Environment variables that should be overridden by config values
fn env_base() -> config::Config {
    let mut builder = config::Config::builder();
    if env::var("NO_COLOR").is_ok() {
        // "User-level configuration files and per-instance command-line arguments
        // should override $NO_COLOR." https://no-color.org/
        builder = builder.set_override("ui.color", "never").unwrap();
    }
    if let Ok(value) = env::var("PAGER") {
        builder = builder.set_override("ui.pager", value).unwrap();
    }
    if let Ok(value) = env::var("VISUAL") {
        builder = builder.set_override("ui.editor", value).unwrap();
    } else if let Ok(value) = env::var("EDITOR") {
        builder = builder.set_override("ui.editor", value).unwrap();
    }

    builder.build().unwrap()
}

pub fn default_config() -> config::Config {
    // Syntax error in default config isn't a user error. That's why defaults are
    // loaded by separate builder.
    macro_rules! from_toml {
        ($file:literal) => {
            config::File::from_str(include_str!($file), config::FileFormat::Toml)
        };
    }
    config::Config::builder()
        .add_source(from_toml!("config/colors.toml"))
        .add_source(from_toml!("config/merge_tools.toml"))
        .add_source(from_toml!("config/misc.toml"))
        .build()
        .unwrap()
}

/// Environment variables that override config values
fn env_overrides() -> config::Config {
    let mut builder = config::Config::builder();
    if let Ok(value) = env::var("JJ_USER") {
        builder = builder.set_override("user.name", value).unwrap();
    }
    if let Ok(value) = env::var("JJ_EMAIL") {
        builder = builder.set_override("user.email", value).unwrap();
    }
    if let Ok(value) = env::var("JJ_TIMESTAMP") {
        builder = builder
            .set_override("debug.commit-timestamp", value)
            .unwrap();
    }
    if let Ok(value) = env::var("JJ_RANDOMNESS_SEED") {
        builder = builder
            .set_override("debug.randomness-seed", value)
            .unwrap();
    }
    if let Ok(value) = env::var("JJ_OP_TIMESTAMP") {
        builder = builder
            .set_override("debug.operation-timestamp", value)
            .unwrap();
    }
    if let Ok(value) = env::var("JJ_OP_HOSTNAME") {
        builder = builder.set_override("operation.hostname", value).unwrap();
    }
    if let Ok(value) = env::var("JJ_OP_USERNAME") {
        builder = builder.set_override("operation.username", value).unwrap();
    }
    if let Ok(value) = env::var("JJ_EDITOR") {
        builder = builder.set_override("ui.editor", value).unwrap();
    }
    builder.build().unwrap()
}

fn read_config_file(path: &Path) -> Result<config::Config, config::ConfigError> {
    config::Config::builder()
        .add_source(
            config::File::from(path)
                .required(false)
                .format(config::FileFormat::Toml),
        )
        .build()
}

fn read_config_path(config_path: &Path) -> Result<config::Config, config::ConfigError> {
    let mut files = vec![];
    if config_path.is_dir() {
        if let Ok(read_dir) = config_path.read_dir() {
            // TODO: Walk the directory recursively?
            for dir_entry in read_dir.flatten() {
                let path = dir_entry.path();
                if path.is_file() {
                    files.push(path);
                }
            }
        }
        files.sort();
    } else {
        files.push(config_path.to_owned());
    }

    files
        .iter()
        .fold(config::Config::builder(), |builder, path| {
            // TODO: Accept other formats and/or accept only certain file extensions?
            builder.add_source(
                config::File::from(path.as_ref())
                    .required(false)
                    .format(config::FileFormat::Toml),
            )
        })
        .build()
}

/// Command name and arguments specified by config.
#[derive(Clone, Debug, Eq, Hash, PartialEq, serde::Deserialize)]
#[serde(untagged)]
pub enum FullCommandArgs {
    String(String),
    Vec(NonEmptyCommandArgsVec),
}

impl FullCommandArgs {
    /// Returns arguments including the command name.
    ///
    /// The list is not empty, but each element may be an empty string.
    pub fn args(&self) -> Cow<[String]> {
        match self {
            // Handle things like `EDITOR=emacs -nw` (TODO: parse shell escapes)
            FullCommandArgs::String(s) => s.split(' ').map(|s| s.to_owned()).collect(),
            FullCommandArgs::Vec(a) => Cow::Borrowed(&a.0),
        }
    }

    /// Returns process builder configured with this.
    pub fn to_command(&self) -> Command {
        let full_args = self.args();
        let mut cmd = Command::new(&full_args[0]);
        cmd.args(&full_args[1..]);
        cmd
    }
}

impl<T: AsRef<str> + ?Sized> From<&T> for FullCommandArgs {
    fn from(s: &T) -> Self {
        FullCommandArgs::String(s.as_ref().to_owned())
    }
}

impl fmt::Display for FullCommandArgs {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            FullCommandArgs::String(s) => write!(f, "{s}"),
            // TODO: format with shell escapes
            FullCommandArgs::Vec(a) => write!(f, "{}", a.0.join(" ")),
        }
    }
}

/// Wrapper to reject an array without command name.
// Based on https://github.com/serde-rs/serde/issues/939
#[derive(Clone, Debug, Eq, Hash, PartialEq, serde::Deserialize)]
#[serde(try_from = "Vec<String>")]
pub struct NonEmptyCommandArgsVec(Vec<String>);

impl TryFrom<Vec<String>> for NonEmptyCommandArgsVec {
    type Error = &'static str;

    fn try_from(args: Vec<String>) -> Result<Self, Self::Error> {
        if args.is_empty() {
            Err("command arguments should not be empty")
        } else {
            Ok(NonEmptyCommandArgsVec(args))
        }
    }
}

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

    #[test]
    fn test_command_args() {
        let config = config::Config::builder()
            .set_override("empty_array", Vec::<String>::new())
            .unwrap()
            .set_override("empty_string", "")
            .unwrap()
            .set_override("array", vec!["emacs", "-nw"])
            .unwrap()
            .set_override("string", "emacs -nw")
            .unwrap()
            .build()
            .unwrap();

        assert!(config.get::<FullCommandArgs>("empty_array").is_err());

        let args: FullCommandArgs = config.get("empty_string").unwrap();
        assert_eq!(args, FullCommandArgs::String("".to_owned()));
        assert_eq!(args.args(), [""].as_ref());

        let args: FullCommandArgs = config.get("array").unwrap();
        assert_eq!(
            args,
            FullCommandArgs::Vec(NonEmptyCommandArgsVec(
                ["emacs", "-nw",].map(|s| s.to_owned()).to_vec()
            ))
        );
        assert_eq!(args.args(), ["emacs", "-nw"].as_ref());

        let args: FullCommandArgs = config.get("string").unwrap();
        assert_eq!(args, FullCommandArgs::String("emacs -nw".to_owned()));
        assert_eq!(args.args(), ["emacs", "-nw"].as_ref());
    }

    #[test]
    fn test_layered_configs_resolved_config_values_empty() {
        let empty_config = config::Config::default();
        let layered_configs = LayeredConfigs {
            default: empty_config.to_owned(),
            env_base: empty_config.to_owned(),
            user: None,
            repo: None,
            env_overrides: empty_config,
            arg_overrides: None,
        };
        assert_eq!(layered_configs.resolved_config_values(&[]).unwrap(), []);
    }

    #[test]
    fn test_layered_configs_resolved_config_values_single_key() {
        let empty_config = config::Config::default();
        let env_base_config = config::Config::builder()
            .set_override("user.name", "base-user-name")
            .unwrap()
            .set_override("user.email", "base@user.email")
            .unwrap()
            .build()
            .unwrap();
        let repo_config = config::Config::builder()
            .set_override("user.email", "repo@user.email")
            .unwrap()
            .build()
            .unwrap();
        let layered_configs = LayeredConfigs {
            default: empty_config.to_owned(),
            env_base: env_base_config,
            user: None,
            repo: Some(repo_config),
            env_overrides: empty_config,
            arg_overrides: None,
        };
        // Note: "email" is alphabetized, before "name" from same layer.
        insta::assert_debug_snapshot!(
            layered_configs.resolved_config_values(&[]).unwrap(),
            @r###"
        [
            AnnotatedValue {
                path: [
                    "user",
                    "email",
                ],
                value: Value {
                    origin: None,
                    kind: String(
                        "base@user.email",
                    ),
                },
                source: Env,
                is_overridden: true,
            },
            AnnotatedValue {
                path: [
                    "user",
                    "name",
                ],
                value: Value {
                    origin: None,
                    kind: String(
                        "base-user-name",
                    ),
                },
                source: Env,
                is_overridden: false,
            },
            AnnotatedValue {
                path: [
                    "user",
                    "email",
                ],
                value: Value {
                    origin: None,
                    kind: String(
                        "repo@user.email",
                    ),
                },
                source: Repo,
                is_overridden: false,
            },
        ]
        "###
        );
    }

    #[test]
    fn test_layered_configs_resolved_config_values_filter_path() {
        let empty_config = config::Config::default();
        let user_config = config::Config::builder()
            .set_override("test-table1.foo", "user-FOO")
            .unwrap()
            .set_override("test-table2.bar", "user-BAR")
            .unwrap()
            .build()
            .unwrap();
        let repo_config = config::Config::builder()
            .set_override("test-table1.bar", "repo-BAR")
            .unwrap()
            .build()
            .unwrap();
        let layered_configs = LayeredConfigs {
            default: empty_config.to_owned(),
            env_base: empty_config.to_owned(),
            user: Some(user_config),
            repo: Some(repo_config),
            env_overrides: empty_config,
            arg_overrides: None,
        };
        insta::assert_debug_snapshot!(
            layered_configs
                .resolved_config_values(&["test-table1"])
                .unwrap(),
            @r###"
        [
            AnnotatedValue {
                path: [
                    "test-table1",
                    "foo",
                ],
                value: Value {
                    origin: None,
                    kind: String(
                        "user-FOO",
                    ),
                },
                source: User,
                is_overridden: false,
            },
            AnnotatedValue {
                path: [
                    "test-table1",
                    "bar",
                ],
                value: Value {
                    origin: None,
                    kind: String(
                        "repo-BAR",
                    ),
                },
                source: Repo,
                is_overridden: false,
            },
        ]
        "###
        );
    }
}