mod.rs

#![deny(clippy::unwrap_used)]
//! This module holds the functionality related to running clang-format and/or
//! clang-tidy.

use std::{
    env::current_dir,
    fmt::{self, Display},
    fs,
    path::{Path, PathBuf},
    process::Command,
    sync::{Arc, Mutex},
};

// non-std crates
use anyhow::{Context, Result, anyhow};
use git2::{DiffOptions, Patch};
use regex::Regex;
use semver::Version;
use tokio::task::JoinSet;
use which::{which, which_in};

// project-specific modules/crates
use super::common_fs::FileObj;
use crate::{
    cli::{ClangParams, RequestedVersion},
    rest_api::{COMMENT_MARKER, RestApiClient, USER_OUTREACH},
};
pub mod clang_format;
use clang_format::run_clang_format;
pub mod clang_tidy;
use clang_tidy::{CompilationUnit, run_clang_tidy};

#[derive(Debug)]
pub enum ClangTool {
    ClangTidy,
    ClangFormat,
}

impl Display for ClangTool {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", self.as_str())
    }
}

impl ClangTool {
    /// Get the string representation of the clang tool's name.
    pub const fn as_str(&self) -> &'static str {
        match self {
            ClangTool::ClangTidy => "clang-tidy",
            ClangTool::ClangFormat => "clang-format",
        }
    }

    /// Fetch the path to an executable clang tool for the specified `version`.
    ///
    /// If the executable is not found using the specified `version`, then the tool is
    /// sought only by it's name ([`Self::as_str()`]).
    ///
    /// The only reason this function would return an error is if the specified tool is not
    /// installed or present on the system (nor in the `PATH` environment variable).
    pub fn get_exe_path(&self, version: &RequestedVersion) -> Result<PathBuf> {
        let name = self.as_str();
        match version {
            RequestedVersion::Path(path_buf) => which_in(
                name,
                Some(path_buf),
                current_dir().with_context(|| "Failed to access current working directory.")?,
            )
            .map_err(|_| anyhow!("Could not find {self} by path")),
            // Thus, we should use whatever is installed and added to $PATH.
            RequestedVersion::SystemDefault | RequestedVersion::NoValue => {
                which(name).map_err(|_| anyhow!("Could not find clang tool by name"))
            }
            RequestedVersion::Requirement(req) => {
                // `req.comparators` has at least a major version number for each comparator.
                // We need to start with the highest major version number first, then
                // decrement to the lowest that satisfies the requirement.

                // find the highest major version from requirement's boundaries.
                let mut it = req.comparators.iter();
                let mut highest_major = it.next().map(|v| v.major).unwrap_or_default() + 1;
                for n in it {
                    if n.major > highest_major {
                        // +1 because we aren't checking the comparator's operator here.
                        highest_major = n.major + 1;
                    }
                }

                // aggregate by decrementing through major versions that satisfy the requirement.
                let mut majors = vec![];
                while highest_major > 0 {
                    // check if the current major version satisfies the requirement.
                    if req.matches(&Version::new(highest_major, 0, 0)) {
                        majors.push(highest_major);
                    }
                    highest_major -= 1;
                }

                // now we're ready to search for the binary exe with the major version suffixed.
                for major in majors {
                    if let Ok(cmd) = which(format!("{self}-{major}")) {
                        return Ok(cmd);
                    }
                }
                // failed to find a binary where the major version number is suffixed to the tool name.

                // USERS SHOULD MAKE SURE THE PROPER VERSION IS INSTALLED BEFORE USING CPP-LINTER!!!
                // This line essentially ignores the version specified as a fail-safe.
                //
                // On Windows, the version's major number is typically not appended to the name of
                // the executable (or symlink for executable), so this is useful in that scenario.
                // On Unix systems, this line is not likely reached. Typically, installing clang
                // will produce a symlink to the executable with the major version appended to the
                // name.
                which(name).map_err(|_| anyhow!("Could not find {self} by version"))
            }
        }
    }

    /// Run `clang-tool --version`, then extract and return the version number.
    fn capture_version(clang_tool: &PathBuf) -> Result<String> {
        let output = Command::new(clang_tool).arg("--version").output()?;
        let stdout = String::from_utf8_lossy(&output.stdout);
        let version_pattern = Regex::new(r"(?i)version[^\d]*([\d.]+)")
            .with_context(|| "Failed to allocate RegExp pattern (for clang version parsing) ")?;
        let captures = version_pattern.captures(&stdout).ok_or(anyhow!(
            "Failed to find version number in `{} --version` output",
            clang_tool.to_string_lossy()
        ))?;
        Ok(captures
            .get(1)
            .ok_or(anyhow!("Failed to get version capture group"))?
            .as_str()
            .to_string())
    }
}

/// This creates a task to run clang-tidy and clang-format on a single file.
///
/// Returns a Future that infallibly resolves to a 2-tuple that contains
///
/// 1. The file's path.
/// 2. A collections of cached logs. A [`Vec`] of tuples that hold
///    - log level
///    - messages
fn analyze_single_file(
    file: Arc<Mutex<FileObj>>,
    clang_params: Arc<ClangParams>,
) -> Result<(PathBuf, Vec<(log::Level, String)>)> {
    let mut file = file
        .lock()
        .map_err(|_| anyhow!("Failed to lock file mutex"))?;
    let mut logs = vec![];
    if clang_params.clang_format_command.is_some() {
        if clang_params
            .format_filter
            .as_ref()
            .is_some_and(|f| f.is_source_or_ignored(file.name.as_path()))
            || clang_params.format_filter.is_none()
        {
            let format_result = run_clang_format(&mut file, &clang_params)?;
            logs.extend(format_result);
        } else {
            logs.push((
                log::Level::Info,
                format!(
                    "{} not scanned by clang-format due to `--ignore-format`",
                    file.name.as_os_str().to_string_lossy()
                ),
            ));
        }
    }
    if clang_params.clang_tidy_command.is_some() {
        if clang_params
            .tidy_filter
            .as_ref()
            .is_some_and(|f| f.is_source_or_ignored(file.name.as_path()))
            || clang_params.tidy_filter.is_none()
        {
            let tidy_result = run_clang_tidy(&mut file, &clang_params)?;
            logs.extend(tidy_result);
        } else {
            logs.push((
                log::Level::Info,
                format!(
                    "{} not scanned by clang-tidy due to `--ignore-tidy`",
                    file.name.as_os_str().to_string_lossy()
                ),
            ));
        }
    }
    Ok((file.name.clone(), logs))
}

/// A struct to contain the version numbers of the clang-tools used
#[derive(Debug, Default)]
pub struct ClangVersions {
    /// The clang-format version used.
    pub format_version: Option<String>,

    /// The clang-tidy version used.
    pub tidy_version: Option<String>,
}

/// Runs clang-tidy and/or clang-format and returns the parsed output from each.
///
/// If `tidy_checks` is `"-*"` then clang-tidy is not executed.
/// If `style` is a blank string (`""`), then clang-format is not executed.
pub async fn capture_clang_tools_output(
    files: &[Arc<Mutex<FileObj>>],
    version: &RequestedVersion,
    mut clang_params: ClangParams,
    rest_api_client: &impl RestApiClient,
) -> Result<ClangVersions> {
    let mut clang_versions = ClangVersions::default();
    // find the executable paths for clang-tidy and/or clang-format and show version
    // info as debugging output.
    if clang_params.tidy_checks != "-*" {
        let exe_path = ClangTool::ClangTidy.get_exe_path(version)?;
        let version_found = ClangTool::capture_version(&exe_path)?;
        log::debug!(
            "{} --version: v{version_found}",
            &exe_path.to_string_lossy()
        );
        clang_versions.tidy_version = Some(version_found);
        clang_params.clang_tidy_command = Some(exe_path);
    }
    if !clang_params.style.is_empty() {
        let exe_path = ClangTool::ClangFormat.get_exe_path(version)?;
        let version_found = ClangTool::capture_version(&exe_path)?;
        log::debug!(
            "{} --version: v{version_found}",
            &exe_path.to_string_lossy()
        );
        clang_versions.format_version = Some(version_found);
        clang_params.clang_format_command = Some(exe_path);
    }

    // parse database (if provided) to match filenames when parsing clang-tidy's stdout
    if let Some(db_path) = &clang_params.database
        && let Ok(db_str) = fs::read(db_path.join("compile_commands.json"))
    {
        clang_params.database_json = Some(
            // A compilation database should be UTF-8 encoded, but file paths are not; use lossy conversion.
            serde_json::from_str::<Vec<CompilationUnit>>(&String::from_utf8_lossy(&db_str))
                .with_context(|| "Failed to parse compile_commands.json")?,
        )
    };

    let mut executors = JoinSet::new();
    let arc_params = Arc::new(clang_params);
    // iterate over the discovered files and run the clang tools
    for file in files {
        let arc_file = file.clone();
        let arc_params = arc_params.clone();
        executors.spawn(async move { analyze_single_file(arc_file, arc_params) });
    }

    while let Some(output) = executors.join_next().await {
        // output?? acts as a fast-fail for any error encountered.
        // This includes any `spawn()` error and any `analyze_single_file()` error.
        // Any unresolved tasks are aborted and dropped when an error is returned here.
        let (file_name, logs) = output??;
        rest_api_client.start_log_group(format!("Analyzing {}", file_name.to_string_lossy()));
        for (level, msg) in logs {
            log::log!(level, "{}", msg);
        }
        rest_api_client.end_log_group();
    }
    Ok(clang_versions)
}

/// A struct to describe a single suggestion in a pull_request review.
pub struct Suggestion {
    /// The file's line number in the diff that begins the suggestion.
    pub line_start: u32,
    /// The file's line number in the diff that ends the suggestion.
    pub line_end: u32,
    /// The actual suggestion.
    pub suggestion: String,
    /// The file that this suggestion pertains to.
    pub path: String,
}

/// A struct to describe the Pull Request review suggestions.
#[derive(Default)]
pub struct ReviewComments {
    /// The total count of suggestions from clang-tidy and clang-format.
    ///
    /// This differs from `comments.len()` because some suggestions may
    /// not fit within the file's diff.
    pub tool_total: [Option<u32>; 2],
    /// A list of comment suggestions to be posted.
    ///
    /// These suggestions are guaranteed to fit in the file's diff.
    pub comments: Vec<Suggestion>,
    /// The complete patch of changes to all files scanned.
    ///
    /// This includes changes from both clang-tidy and clang-format
    /// (assembled in that order).
    pub full_patch: [String; 2],
}

impl ReviewComments {
    pub fn summarize(&self, clang_versions: &ClangVersions) -> String {
        let mut body = format!("{COMMENT_MARKER}## Cpp-linter Review\n");
        for t in 0_usize..=1 {
            let mut total = 0;
            let (tool_name, tool_version) = if t == 0 {
                ("clang-format", clang_versions.format_version.as_ref())
            } else {
                ("clang-tidy", clang_versions.tidy_version.as_ref())
            };
            if tool_version.is_none() {
                // this tool was not used at all
                continue;
            }
            let tool_total = self.tool_total[t].unwrap_or_default();

            // If the tool's version is unknown, then we don't need to output this line.
            // NOTE: If the tool was invoked at all, then the tool's version shall be known.
            if let Some(ver_str) = tool_version {
                body.push_str(format!("\n### Used {tool_name} v{ver_str}\n").as_str());
            }
            for comment in &self.comments {
                if comment
                    .suggestion
                    .contains(format!("### {tool_name}").as_str())
                {
                    total += 1;
                }
            }

            if total != tool_total {
                body.push_str(
                    format!(
                        "\nOnly {total} out of {tool_total} {tool_name} concerns fit within this pull request's diff.\n",
                    )
                    .as_str(),
                );
            }
            if !self.full_patch[t].is_empty() {
                body.push_str(
                    format!(
                        "\n<details><summary>Click here for the full {tool_name} patch</summary>\n\n```diff\n{}```\n\n</details>\n",
                        self.full_patch[t]
                    ).as_str()
                );
            } else {
                body.push_str(
                    format!(
                        "\nNo concerns reported by {}. Great job! :tada:\n",
                        tool_name
                    )
                    .as_str(),
                )
            }
        }
        body.push_str(USER_OUTREACH);
        body
    }

    pub fn is_comment_in_suggestions(&mut self, comment: &Suggestion) -> bool {
        for s in &mut self.comments {
            if s.path == comment.path
                && s.line_end == comment.line_end
                && s.line_start == comment.line_start
            {
                s.suggestion.push('\n');
                s.suggestion.push_str(comment.suggestion.as_str());
                return true;
            }
        }
        false
    }
}

pub fn make_patch<'buffer>(
    path: &Path,
    patched: &'buffer [u8],
    original_content: &'buffer [u8],
) -> Result<Patch<'buffer>> {
    let mut diff_opts = &mut DiffOptions::new();
    diff_opts = diff_opts.indent_heuristic(true);
    diff_opts = diff_opts.context_lines(0);
    let patch = Patch::from_buffers(
        original_content,
        Some(path),
        patched,
        Some(path),
        Some(diff_opts),
    )
    .with_context(|| {
        format!(
            "Failed to create patch for file {}.",
            path.to_string_lossy()
        )
    })?;
    Ok(patch)
}

pub trait MakeSuggestions {
    /// Create some user-facing helpful info about what the suggestion aims to resolve.
    fn get_suggestion_help(&self, start_line: u32, end_line: u32) -> String;

    /// Get the tool's name which generated the advice.
    fn get_tool_name(&self) -> String;

    /// Create a bunch of suggestions from a [`FileObj`]'s advice's generated `patched` buffer.
    fn get_suggestions(
        &self,
        review_comments: &mut ReviewComments,
        file_obj: &FileObj,
        patch: &mut Patch,
        summary_only: bool,
    ) -> Result<()> {
        let is_tidy_tool = (&self.get_tool_name() == "clang-tidy") as usize;
        let hunks_total = patch.num_hunks();
        let mut hunks_in_patch = 0u32;
        let file_name = file_obj
            .name
            .to_string_lossy()
            .replace("\\", "/")
            .trim_start_matches("./")
            .to_owned();
        let patch_buf = &patch
            .to_buf()
            .with_context(|| "Failed to convert patch to byte array")?
            .to_vec();
        review_comments.full_patch[is_tidy_tool].push_str(
            String::from_utf8(patch_buf.to_owned())
                .with_context(|| format!("Failed to convert patch to string: {file_name}"))?
                .as_str(),
        );
        if summary_only {
            review_comments.tool_total[is_tidy_tool].get_or_insert(0);
            return Ok(());
        }
        for hunk_id in 0..hunks_total {
            let (hunk, line_count) = patch.hunk(hunk_id).with_context(|| {
                format!("Failed to get hunk {hunk_id} from patch for {file_name}")
            })?;
            hunks_in_patch += 1;
            let hunk_range = file_obj.is_hunk_in_diff(&hunk);
            match hunk_range {
                None => continue,
                Some((start_line, end_line)) => {
                    let mut suggestion = String::new();
                    let suggestion_help = self.get_suggestion_help(start_line, end_line);
                    let mut removed = vec![];
                    for line_index in 0..line_count {
                        let diff_line = patch
                            .line_in_hunk(hunk_id, line_index)
                            .with_context(|| format!("Failed to get line {line_index} in a hunk {hunk_id} of patch for {file_name}"))?;
                        let line = String::from_utf8(diff_line.content().to_owned())
                            .with_context(|| format!("Failed to convert line {line_index} buffer to string in hunk {hunk_id} of patch for {file_name}"))?;
                        if ['+', ' '].contains(&diff_line.origin()) {
                            suggestion.push_str(line.as_str());
                        } else {
                            removed.push(
                                diff_line
                                    .old_lineno()
                                    .expect("Removed line should have a line number"),
                            );
                        }
                    }
                    if suggestion.is_empty() && !removed.is_empty() {
                        suggestion.push_str(
                            format!(
                                "Please remove the line(s)\n- {}",
                                removed
                                    .iter()
                                    .map(|l| l.to_string())
                                    .collect::<Vec<String>>()
                                    .join("\n- ")
                            )
                            .as_str(),
                        )
                    } else {
                        suggestion = format!("```suggestion\n{suggestion}```");
                    }
                    let comment = Suggestion {
                        line_start: start_line,
                        line_end: end_line,
                        suggestion: format!("{suggestion_help}\n{suggestion}"),
                        path: file_name.clone(),
                    };
                    if !review_comments.is_comment_in_suggestions(&comment) {
                        review_comments.comments.push(comment);
                    }
                }
            }
        }
        review_comments.tool_total[is_tidy_tool] =
            Some(review_comments.tool_total[is_tidy_tool].unwrap_or_default() + hunks_in_patch);
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use std::{path::PathBuf, str::FromStr};

    use which::which;

    use super::ClangTool;
    use crate::cli::RequestedVersion;

    const CLANG_FORMAT: ClangTool = ClangTool::ClangFormat;

    #[test]
    fn get_exe_by_version() {
        let requirement = ">=9, <22";
        let req_version = RequestedVersion::from_str(requirement).unwrap();
        let tool_exe = CLANG_FORMAT.get_exe_path(&req_version);
        println!("tool_exe: {:?}", tool_exe);
        assert!(tool_exe.is_ok_and(|val| {
            val.file_name()
                .unwrap()
                .to_string_lossy()
                .to_string()
                .contains(CLANG_FORMAT.as_str())
        }));
    }

    #[test]
    fn get_exe_by_default() {
        let tool_exe = CLANG_FORMAT.get_exe_path(&RequestedVersion::from_str("").unwrap());
        println!("tool_exe: {:?}", tool_exe);
        assert!(tool_exe.is_ok_and(|val| {
            val.file_name()
                .unwrap()
                .to_string_lossy()
                .to_string()
                .contains(CLANG_FORMAT.as_str())
        }));
    }

    #[test]
    fn get_exe_by_path() {
        static TOOL_NAME: &'static str = CLANG_FORMAT.as_str();
        let clang_version = which(TOOL_NAME).unwrap();
        let bin_path = clang_version.parent().unwrap().to_str().unwrap();
        println!("binary exe path: {bin_path}");
        let tool_exe = CLANG_FORMAT.get_exe_path(&RequestedVersion::from_str(bin_path).unwrap());
        println!("tool_exe: {:?}", tool_exe);
        assert!(tool_exe.is_ok_and(|val| {
            val.file_name()
                .unwrap()
                .to_string_lossy()
                .to_string()
                .contains(TOOL_NAME)
        }));
    }

    #[test]
    fn get_exe_by_invalid_path() {
        let tool_exe =
            CLANG_FORMAT.get_exe_path(&RequestedVersion::Path(PathBuf::from("non-existent-path")));
        assert!(tool_exe.is_err());
    }
}