format.rs

use std::fmt::{Display, Formatter};
use std::fs::File;
use std::io;
use std::io::{stderr, stdout, Write};
use std::path::{Path, PathBuf};
use std::time::Instant;

use anyhow::Result;
use colored::Colorize;
use itertools::Itertools;
use log::{error, warn};
use rayon::iter::Either::{Left, Right};
use rayon::iter::{IntoParallelRefIterator, ParallelIterator};
use similar::TextDiff;
use thiserror::Error;
use tracing::debug;

use ruff_diagnostics::SourceMap;
use ruff_linter::fs;
use ruff_linter::logging::LogLevel;
use ruff_linter::registry::Rule;
use ruff_linter::settings::rule_table::RuleTable;
use ruff_linter::source_kind::{SourceError, SourceKind};
use ruff_linter::warn_user_once;
use ruff_python_ast::{PySourceType, SourceType};
use ruff_python_formatter::{format_module_source, FormatModuleError};
use ruff_text_size::{TextLen, TextRange, TextSize};
use ruff_workspace::resolver::{
    match_exclusion, python_files_in_path, PyprojectConfig, ResolvedFile, Resolver,
};
use ruff_workspace::FormatterSettings;

use crate::args::{CliOverrides, FormatArguments};
use crate::cache::{Cache, FileCacheKey, PackageCacheMap, PackageCaches};
use crate::panic::{catch_unwind, PanicError};
use crate::resolve::resolve;
use crate::ExitStatus;

#[derive(Debug, Copy, Clone, is_macro::Is)]
pub(crate) enum FormatMode {
    /// Write the formatted contents back to the file.
    Write,
    /// Check if the file is formatted, but do not write the formatted contents back.
    Check,
    /// Check if the file is formatted, show a diff if not.
    Diff,
}

impl FormatMode {
    pub(crate) fn from_cli(cli: &FormatArguments) -> Self {
        if cli.diff {
            FormatMode::Diff
        } else if cli.check {
            FormatMode::Check
        } else {
            FormatMode::Write
        }
    }
}

/// Format a set of files, and return the exit status.
pub(crate) fn format(
    cli: &FormatArguments,
    overrides: &CliOverrides,
    log_level: LogLevel,
) -> Result<ExitStatus> {
    let pyproject_config = resolve(
        cli.isolated,
        cli.config.as_deref(),
        overrides,
        cli.stdin_filename.as_deref(),
    )?;
    let mode = FormatMode::from_cli(cli);
    let (paths, resolver) = python_files_in_path(&cli.files, &pyproject_config, overrides)?;

    if paths.is_empty() {
        warn_user_once!("No Python files found under the given path(s)");
        return Ok(ExitStatus::Success);
    }

    warn_incompatible_formatter_settings(&pyproject_config, Some(&resolver));

    // Discover the package root for each Python file.
    let package_roots = resolver.package_roots(
        &paths
            .iter()
            .flatten()
            .map(ResolvedFile::path)
            .collect::<Vec<_>>(),
        &pyproject_config,
    );

    let caches = if cli.no_cache {
        None
    } else {
        // `--no-cache` doesn't respect code changes, and so is often confusing during
        // development.
        #[cfg(debug_assertions)]
        crate::warn_user!("Detected debug build without --no-cache.");

        Some(PackageCacheMap::init(
            &pyproject_config,
            &package_roots,
            &resolver,
        ))
    };

    let start = Instant::now();
    let (results, mut errors): (Vec<_>, Vec<_>) = paths
        .par_iter()
        .filter_map(|entry| {
            match entry {
                Ok(resolved_file) => {
                    let path = resolved_file.path();
                    let SourceType::Python(source_type) = SourceType::from(&path) else {
                        // Ignore any non-Python files.
                        return None;
                    };

                    let resolved_settings = resolver.resolve(path, &pyproject_config);

                    // Ignore files that are excluded from formatting
                    if !resolved_file.is_root()
                        && match_exclusion(
                            path,
                            resolved_file.file_name(),
                            &resolved_settings.formatter.exclude,
                        )
                    {
                        return None;
                    }

                    let package = path
                        .parent()
                        .and_then(|parent| package_roots.get(parent).copied())
                        .flatten();
                    let cache_root = package.unwrap_or_else(|| path.parent().unwrap_or(path));
                    let cache = caches.get(cache_root);

                    Some(
                        match catch_unwind(|| {
                            format_path(
                                path,
                                &resolved_settings.formatter,
                                source_type,
                                mode,
                                cache,
                            )
                        }) {
                            Ok(inner) => inner.map(|result| FormatPathResult {
                                path: resolved_file.path().to_path_buf(),
                                result,
                            }),
                            Err(error) => Err(FormatCommandError::Panic(
                                Some(resolved_file.path().to_path_buf()),
                                error,
                            )),
                        },
                    )
                }
                Err(err) => Some(Err(FormatCommandError::Ignore(err.clone()))),
            }
        })
        .partition_map(|result| match result {
            Ok(diagnostic) => Left(diagnostic),
            Err(err) => Right(err),
        });
    let duration = start.elapsed();

    debug!(
        "Formatted {} files in {:.2?}",
        results.len() + errors.len(),
        duration
    );

    caches.persist()?;

    // Report on any errors.
    errors.sort_unstable_by(|a, b| a.path().cmp(&b.path()));

    for error in &errors {
        error!("{error}");
    }

    let results = FormatResults::new(results.as_slice(), mode);
    match mode {
        FormatMode::Write => {}
        FormatMode::Check => {
            results.write_changed(&mut stdout().lock())?;
        }
        FormatMode::Diff => {
            results.write_diff(&mut stdout().lock())?;
        }
    }

    // Report on the formatting changes.
    if log_level >= LogLevel::Default {
        if mode.is_diff() {
            // Allow piping the diff to e.g. a file by writing the summary to stderr
            results.write_summary(&mut stderr().lock())?;
        } else {
            results.write_summary(&mut stdout().lock())?;
        }
    }

    match mode {
        FormatMode::Write => {
            if errors.is_empty() {
                Ok(ExitStatus::Success)
            } else {
                Ok(ExitStatus::Error)
            }
        }
        FormatMode::Check | FormatMode::Diff => {
            if errors.is_empty() {
                if results.any_formatted() {
                    Ok(ExitStatus::Failure)
                } else {
                    Ok(ExitStatus::Success)
                }
            } else {
                Ok(ExitStatus::Error)
            }
        }
    }
}

/// Format the file at the given [`Path`].
#[tracing::instrument(level="debug", skip_all, fields(path = %path.display()))]
pub(crate) fn format_path(
    path: &Path,
    settings: &FormatterSettings,
    source_type: PySourceType,
    mode: FormatMode,
    cache: Option<&Cache>,
) -> Result<FormatResult, FormatCommandError> {
    if let Some(cache) = cache {
        let relative_path = cache
            .relative_path(path)
            .expect("wrong package cache for file");

        if let Ok(cache_key) = FileCacheKey::from_path(path) {
            if cache.is_formatted(relative_path, &cache_key) {
                return Ok(FormatResult::Unchanged);
            }
        }
    }

    // Extract the sources from the file.
    let unformatted = match SourceKind::from_path(path, source_type) {
        Ok(Some(source_kind)) => source_kind,
        // Non Python Jupyter notebook
        Ok(None) => return Ok(FormatResult::Skipped),
        Err(err) => {
            return Err(FormatCommandError::Read(Some(path.to_path_buf()), err));
        }
    };

    // Format the source.
    let format_result = match format_source(&unformatted, source_type, Some(path), settings)? {
        FormattedSource::Formatted(formatted) => match mode {
            FormatMode::Write => {
                let mut writer = File::create(path).map_err(|err| {
                    FormatCommandError::Write(Some(path.to_path_buf()), err.into())
                })?;
                formatted
                    .write(&mut writer)
                    .map_err(|err| FormatCommandError::Write(Some(path.to_path_buf()), err))?;

                if let Some(cache) = cache {
                    if let Ok(cache_key) = FileCacheKey::from_path(path) {
                        let relative_path = cache
                            .relative_path(path)
                            .expect("wrong package cache for file");
                        cache.set_formatted(relative_path.to_path_buf(), &cache_key);
                    }
                }

                FormatResult::Formatted
            }
            FormatMode::Check => FormatResult::Formatted,
            FormatMode::Diff => FormatResult::Diff {
                unformatted,
                formatted,
            },
        },
        FormattedSource::Unchanged => {
            if let Some(cache) = cache {
                if let Ok(cache_key) = FileCacheKey::from_path(path) {
                    let relative_path = cache
                        .relative_path(path)
                        .expect("wrong package cache for file");
                    cache.set_formatted(relative_path.to_path_buf(), &cache_key);
                }
            }

            FormatResult::Unchanged
        }
    };

    Ok(format_result)
}

#[derive(Debug)]
pub(crate) enum FormattedSource {
    /// The source was formatted, and the [`SourceKind`] contains the transformed source code.
    Formatted(SourceKind),
    /// The source was unchanged.
    Unchanged,
}

impl From<FormattedSource> for FormatResult {
    fn from(value: FormattedSource) -> Self {
        match value {
            FormattedSource::Formatted(_) => FormatResult::Formatted,
            FormattedSource::Unchanged => FormatResult::Unchanged,
        }
    }
}

/// Format a [`SourceKind`], returning the transformed [`SourceKind`], or `None` if the source was
/// unchanged.
pub(crate) fn format_source(
    source_kind: &SourceKind,
    source_type: PySourceType,
    path: Option<&Path>,
    settings: &FormatterSettings,
) -> Result<FormattedSource, FormatCommandError> {
    match source_kind {
        SourceKind::Python(unformatted) => {
            let options = settings.to_format_options(source_type, unformatted);

            let formatted = format_module_source(unformatted, options)
                .map_err(|err| FormatCommandError::Format(path.map(Path::to_path_buf), err))?;

            let formatted = formatted.into_code();
            if formatted.len() == unformatted.len() && formatted == *unformatted {
                Ok(FormattedSource::Unchanged)
            } else {
                Ok(FormattedSource::Formatted(SourceKind::Python(formatted)))
            }
        }
        SourceKind::IpyNotebook(notebook) => {
            if !notebook.is_python_notebook() {
                return Ok(FormattedSource::Unchanged);
            }

            let options = settings.to_format_options(source_type, notebook.source_code());

            let mut output: Option<String> = None;
            let mut last: Option<TextSize> = None;
            let mut source_map = SourceMap::default();

            // Format each cell individually.
            for (start, end) in notebook.cell_offsets().iter().tuple_windows::<(_, _)>() {
                let range = TextRange::new(*start, *end);
                let unformatted = &notebook.source_code()[range];

                // Format the cell.
                let formatted = format_module_source(unformatted, options.clone())
                    .map_err(|err| FormatCommandError::Format(path.map(Path::to_path_buf), err))?;

                // If the cell is unchanged, skip it.
                let formatted = formatted.as_code();
                if formatted.len() == unformatted.len() && formatted == unformatted {
                    continue;
                }

                // If this is the first newly-formatted cell, initialize the output.
                let output = output
                    .get_or_insert_with(|| String::with_capacity(notebook.source_code().len()));

                // Add all contents from `last` to the current cell.
                let slice = &notebook.source_code()
                    [TextRange::new(last.unwrap_or_default(), range.start())];
                output.push_str(slice);

                // Add the start source marker for the cell.
                source_map.push_marker(*start, output.text_len());

                // Add the cell itself.
                output.push_str(formatted);

                // Add the end source marker for the added cell.
                source_map.push_marker(*end, output.text_len());

                // Track that the cell was formatted.
                last = Some(*end);
            }

            // If the file was unchanged, return `None`.
            let (Some(mut output), Some(last)) = (output, last) else {
                return Ok(FormattedSource::Unchanged);
            };

            // Add the remaining content.
            let slice = &notebook.source_code()[usize::from(last)..];
            output.push_str(slice);

            // Update the notebook.
            let mut formatted = notebook.clone();
            formatted.update(&source_map, output);

            Ok(FormattedSource::Formatted(SourceKind::IpyNotebook(
                formatted,
            )))
        }
    }
}

/// The result of an individual formatting operation.
#[derive(Debug, Clone, is_macro::Is)]
pub(crate) enum FormatResult {
    /// The file was formatted.
    Formatted,
    /// The file was formatted, [`SourceKind`] contains the formatted code
    Diff {
        unformatted: SourceKind,
        formatted: SourceKind,
    },
    /// The file was unchanged, as the formatted contents matched the existing contents.
    Unchanged,

    /// Skipped formatting because its an unsupported file format
    Skipped,
}

/// The coupling of a [`FormatResult`] with the path of the file that was analyzed.
#[derive(Debug)]
struct FormatPathResult {
    path: PathBuf,
    result: FormatResult,
}

/// The results of formatting a set of files
#[derive(Debug)]
struct FormatResults<'a> {
    /// The individual formatting results.
    results: &'a [FormatPathResult],
    /// The format mode that was used.
    mode: FormatMode,
}

impl<'a> FormatResults<'a> {
    fn new(results: &'a [FormatPathResult], mode: FormatMode) -> Self {
        Self { results, mode }
    }

    /// Returns `true` if any of the files require formatting.
    fn any_formatted(&self) -> bool {
        self.results.iter().any(|result| match result.result {
            FormatResult::Formatted | FormatResult::Diff { .. } => true,
            FormatResult::Unchanged | FormatResult::Skipped => false,
        })
    }

    /// Write a diff of the formatting changes to the given writer.
    fn write_diff(&self, f: &mut impl Write) -> io::Result<()> {
        for (path, unformatted, formatted) in self
            .results
            .iter()
            .filter_map(|result| {
                if let FormatResult::Diff {
                    unformatted,
                    formatted,
                } = &result.result
                {
                    Some((result.path.as_path(), unformatted, formatted))
                } else {
                    None
                }
            })
            .sorted_unstable_by_key(|(path, _, _)| *path)
        {
            let text_diff =
                TextDiff::from_lines(unformatted.source_code(), formatted.source_code());
            let mut unified_diff = text_diff.unified_diff();
            unified_diff.header(&fs::relativize_path(path), &fs::relativize_path(path));
            unified_diff.to_writer(&mut *f)?;
        }

        Ok(())
    }

    /// Write a list of the files that would be changed to the given writer.
    fn write_changed(&self, f: &mut impl Write) -> io::Result<()> {
        for path in self
            .results
            .iter()
            .filter_map(|result| {
                if result.result.is_formatted() {
                    Some(result.path.as_path())
                } else {
                    None
                }
            })
            .sorted_unstable()
        {
            writeln!(f, "Would reformat: {}", fs::relativize_path(path).bold())?;
        }

        Ok(())
    }

    /// Write a summary of the formatting results to the given writer.
    fn write_summary(&self, f: &mut impl Write) -> io::Result<()> {
        // Compute the number of changed and unchanged files.
        let mut changed = 0u32;
        let mut unchanged = 0u32;
        for result in self.results {
            match &result.result {
                FormatResult::Formatted => {
                    changed += 1;
                }
                FormatResult::Unchanged => unchanged += 1,
                FormatResult::Diff { .. } => {
                    changed += 1;
                }
                FormatResult::Skipped => {}
            }
        }

        // Write out a summary of the formatting results.
        if changed > 0 && unchanged > 0 {
            writeln!(
                f,
                "{} file{} {}, {} file{} left unchanged",
                changed,
                if changed == 1 { "" } else { "s" },
                match self.mode {
                    FormatMode::Write => "reformatted",
                    FormatMode::Check | FormatMode::Diff => "would be reformatted",
                },
                unchanged,
                if unchanged == 1 { "" } else { "s" },
            )
        } else if changed > 0 {
            writeln!(
                f,
                "{} file{} {}",
                changed,
                if changed == 1 { "" } else { "s" },
                match self.mode {
                    FormatMode::Write => "reformatted",
                    FormatMode::Check | FormatMode::Diff => "would be reformatted",
                }
            )
        } else if unchanged > 0 {
            writeln!(
                f,
                "{} file{} left unchanged",
                unchanged,
                if unchanged == 1 { "" } else { "s" },
            )
        } else {
            Ok(())
        }
    }
}

/// An error that can occur while formatting a set of files.
#[derive(Error, Debug)]
pub(crate) enum FormatCommandError {
    Ignore(#[from] ignore::Error),
    Panic(Option<PathBuf>, PanicError),
    Read(Option<PathBuf>, SourceError),
    Format(Option<PathBuf>, FormatModuleError),
    Write(Option<PathBuf>, SourceError),
}

impl FormatCommandError {
    fn path(&self) -> Option<&Path> {
        match self {
            Self::Ignore(err) => {
                if let ignore::Error::WithPath { path, .. } = err {
                    Some(path.as_path())
                } else {
                    None
                }
            }
            Self::Panic(path, _)
            | Self::Read(path, _)
            | Self::Format(path, _)
            | Self::Write(path, _) => path.as_deref(),
        }
    }
}

impl Display for FormatCommandError {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Ignore(err) => {
                if let ignore::Error::WithPath { path, .. } = err {
                    write!(
                        f,
                        "{}{}{} {}",
                        "Failed to format ".bold(),
                        fs::relativize_path(path).bold(),
                        ":".bold(),
                        err.io_error()
                            .map_or_else(|| err.to_string(), std::string::ToString::to_string)
                    )
                } else {
                    write!(
                        f,
                        "{} {}",
                        "Encountered error:".bold(),
                        err.io_error()
                            .map_or_else(|| err.to_string(), std::string::ToString::to_string)
                    )
                }
            }
            Self::Read(path, err) => {
                if let Some(path) = path {
                    write!(
                        f,
                        "{}{}{} {err}",
                        "Failed to read ".bold(),
                        fs::relativize_path(path).bold(),
                        ":".bold()
                    )
                } else {
                    write!(f, "{}{} {err}", "Failed to read".bold(), ":".bold())
                }
            }
            Self::Write(path, err) => {
                if let Some(path) = path {
                    write!(
                        f,
                        "{}{}{} {err}",
                        "Failed to write ".bold(),
                        fs::relativize_path(path).bold(),
                        ":".bold()
                    )
                } else {
                    write!(f, "{}{} {err}", "Failed to write".bold(), ":".bold())
                }
            }
            Self::Format(path, err) => {
                if let Some(path) = path {
                    write!(
                        f,
                        "{}{}{} {err}",
                        "Failed to format ".bold(),
                        fs::relativize_path(path).bold(),
                        ":".bold()
                    )
                } else {
                    write!(f, "{}{} {err}", "Failed to format".bold(), ":".bold())
                }
            }
            Self::Panic(path, err) => {
                let message = r#"This indicates a bug in Ruff. If you could open an issue at:

    https://github.com/astral-sh/ruff/issues/new?title=%5BFormatter%20panic%5D

...with the relevant file contents, the `pyproject.toml` settings, and the following stack trace, we'd be very appreciative!
"#;
                if let Some(path) = path {
                    write!(
                        f,
                        "{}{}{} {message}\n{err}",
                        "Panicked while formatting ".bold(),
                        fs::relativize_path(path).bold(),
                        ":".bold()
                    )
                } else {
                    write!(
                        f,
                        "{} {message}\n{err}",
                        "Panicked while formatting.".bold()
                    )
                }
            }
        }
    }
}

pub(super) fn warn_incompatible_formatter_settings(
    pyproject_config: &PyprojectConfig,
    resolver: Option<&Resolver>,
) {
    for setting in std::iter::once(&pyproject_config.settings)
        .chain(resolver.iter().flat_map(|resolver| resolver.settings()))
    {
        let mut incompatible_rules = Vec::new();

        for incompatible_rule in RuleTable::from_iter([
            Rule::LineTooLong,
            Rule::TabIndentation,
            Rule::IndentationWithInvalidMultiple,
            Rule::IndentationWithInvalidMultipleComment,
            Rule::OverIndented,
            Rule::IndentWithSpaces,
            Rule::SingleLineImplicitStringConcatenation,
            Rule::MissingTrailingComma,
            Rule::ProhibitedTrailingComma,
            Rule::BadQuotesInlineString,
            Rule::BadQuotesMultilineString,
            Rule::BadQuotesDocstring,
            Rule::AvoidableEscapedQuote,
        ])
        .iter_enabled()
        {
            if setting.linter.rules.enabled(incompatible_rule) {
                incompatible_rules.push(format!("'{}'", incompatible_rule.noqa_code()));
            }
        }

        if !incompatible_rules.is_empty() {
            incompatible_rules.sort();
            warn!("The following rules may cause conflicts when used with the formatter: {}. To avoid unexpected behavior, we recommend disabling these rules, either by removing them from the `select` or `extend-select` configuration, or adding then to the `ignore` configuration.", incompatible_rules.join(", "));
        }

        if setting.linter.rules.enabled(Rule::UnsortedImports) {
            // The formatter removes empty lines if the value is larger than 2 but always inserts a empty line after imports.
            // Two empty lines are okay because `isort` only uses this setting for top-level imports (not in nested blocks).
            if !matches!(setting.linter.isort.lines_after_imports, 1 | 2 | -1) {
                warn!("The isort option 'isort.lines-after-imports' with a value other than `-1`, `1` or `2` is incompatible with the formatter. To avoid unexpected behavior, we recommend setting the option to one of: `2`, `1`, or `-1` (default).");
            }

            // Values larger than two get reduced to one line by the formatter if the import is in a nested block.
            if setting.linter.isort.lines_between_types > 1 {
                warn!("The isort option 'isort.lines-between-types' with a value larger than 1 is incompatible with the formatter. To avoid unexpected behavior, we recommend setting the option to one of: `1` or `0` (default).");
            }

            // isort inserts a trailing comma which the formatter preserves, but only if `skip-magic-trailing-comma` isn't false.
            if setting.formatter.magic_trailing_comma.is_ignore() {
                if setting.linter.isort.force_wrap_aliases {
                    warn!("The isort option 'isort.force-wrap-aliases' is incompatible with the formatter 'format.skip-magic-trailing-comma=true' option. To avoid unexpected behavior, we recommend either setting 'isort.force-wrap-aliases=false' or 'format.skip-magic-trailing-comma=false'.");
                }

                if setting.linter.isort.split_on_trailing_comma {
                    warn!("The isort option 'isort.split-on-trailing-comma' is incompatible with the formatter 'format.skip-magic-trailing-comma=true' option. To avoid unexpected behavior, we recommend either setting 'isort.split-on-trailing-comma=false' or 'format.skip-magic-trailing-comma=false'.");
                }
            }
        }
    }
}