gitlab_clippy 1.0.3

use anyhow::Result;
use cargo_metadata::{diagnostic::DiagnosticLevel, Message};
use itertools::process_results;
use md5::compute;
use serde::Serialize;
use std::io::{BufRead, Write};

/// Code Quality report artifact implementing a subset of the Code Climate spec
/// per [documentation](https://docs.gitlab.com/ee/user/project/merge_requests/code_quality.html#implementing-a-custom-tool)
#[derive(Debug, Serialize)]
pub struct GitLabCodeQuality {
    /// A description of the code quality violation
    pub description: String,
    /// A unique fingerprint to identify the code quality violation
    pub fingerprint: String,
    /// See `Location` documentation for details
    pub location: Location,
    /// The potential impact of the issue found (info, minor, major, critical, or blocker)
    pub severity: String,
}

impl GitLabCodeQuality {
    /// Calculates MD5 hash from parameters
    fn calculate_fingerprint(message: &str, file: &str, line: usize) -> String {
        let fingerprint = format!("{}{}{}", message, file, line);
        let digest = compute(Vec::from(fingerprint));
        format!("{:x}", digest)
    }

    /// Easy to use constructor
    pub fn new(message: &str, file: &str, line: usize, severity: &str) -> Self {
        Self {
            description: String::from(message),
            fingerprint: Self::calculate_fingerprint(message, file, line),
            location: Location {
                path: String::from(file),
                lines: Lines { begin: line },
            },
            severity: String::from(severity),
        }
    }
}

/// The relative path to the file containing the code quality violation
#[derive(Debug, Serialize)]
pub struct Location {
    /// The relative path to the file
    pub path: String,
    /// See `Lines` documentation for details
    pub lines: Lines,
}

#[derive(Debug, Serialize)]
/// Contains the line information for code quality violation
pub struct Lines {
    /// The line on which the code quality violation occurred
    pub begin: usize,
}

/// Returns a vector of `GitLabCQ` from a compiler message
///
/// # Arguments
///
/// * `message` - A cargo message
fn parse_compiler_message(message: &Message) -> Vec<GitLabCodeQuality> {
    match message {
        Message::CompilerMessage(msg) => {
            let message = &msg.message;
            message
                .spans
                .iter()
                .map(|span| {
                    GitLabCodeQuality::new(
                        &message.message,
                        &span.file_name,
                        span.line_start,
                        match message.level {
                            DiagnosticLevel::Help | DiagnosticLevel::Note => "info",
                            DiagnosticLevel::Warning => "minor",
                            DiagnosticLevel::Error => "major",
                            _ => "",
                        },
                    )
                })
                .collect()
        }
        _ => vec![],
    }
}

fn process<R: BufRead>(reader: R) -> Result<Vec<GitLabCodeQuality>, std::io::Error> {
    process_results(Message::parse_stream(reader), |input| {
        input
            .flat_map(|message| parse_compiler_message(&message))
            .collect()
    })
}

/// Returns a vector of `GitLabCQ` serialized into a JSON stream
///
/// # Arguments
///
/// * `reader` - A `BufRead` of cargo output
/// * `writer` - A `Writer` to write the results to
pub fn parse_to_writer<R: BufRead, W: Write>(reader: R, writer: W) -> Result<()> {
    let results = process(reader)?;
    serde_json::to_writer_pretty(writer, &results)?;
    Ok(())
}

/// Returns a vector of `GitLabCQ` serialized into a JSON string
///
/// # Arguments
///
/// * `reader` - A `BufRead` of cargo output
pub fn parse_to_string<R: BufRead>(reader: R) -> Result<String> {
    let results = process(reader)?;
    let json = serde_json::to_string_pretty(&results)?;
    Ok(json)
}

/// Deprecated, please use lib::parse_to_string() instead.
///
/// # Arguments
///
/// * `reader` - A `BufRead` of cargo output
#[deprecated(since = "0.2.0", note = "please use `lib::parse_to_string` instead")]
pub fn parse<R: BufRead>(reader: R) -> Result<String> {
    parse_to_string(reader)
}

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

    proptest! {
        #[test]
        fn fingerprint_is_unique(message1 in "\\PC*", message2 in "\\PC*", file1 in "\\PC*", file2 in "\\PC*", line1 in 0usize..10000, line2 in 0usize..10000) {
            let fingerprint1 = GitLabCodeQuality::calculate_fingerprint(&message1, &file1, line1);
            let fingerprint2 = GitLabCodeQuality::calculate_fingerprint(&message2, &file2, line2);
            assert_ne!(fingerprint1, fingerprint2);
        }
    }
}