indicate 0.2.0

//! Module to parse the output of `cargo-geiger`
//!
//! This module relies on the using the flags `--output-format Json --quiet`.
//! The output can still be quite noicy, so sometimes running `2>/dev/null` is
//! required (pipe `stderr` to the black hole at the center of the Linuxverse).
//!
//! The output of `cargo-geiger` is on the form (some fields omitted)
//! ```json
//! {
//!     "packages": [
//!         {
//!             "package": {
//!                 "id": {
//!                     "name": "libc",
//!                     "version": "0.2.139",
//!                     // Etc.
//!                 },
//!                 "unsafety": {
//!                     "used": {
//!                         "functions": {"safe":0,"unsafe_":0},
//!                         "exprs": {"safe":253,"unsafe_":12},
//!                         "item_impls": {"safe":11,"unsafe_":0},
//!                         "item_traits":{"safe":0,"unsafe_":0},
//!                         "methods":{"safe":5,"unsafe_":2}
//!                     },
//!                     "unused": {
//!                         "functions": {"safe":6,"unsafe_":24},
//!                         "exprs": {"safe":3934,"unsafe_":432},
//!                         "item_impls": {"safe":103,"unsafe_":2},
//!                         "item_traits": {"safe":0,"unsafe_":0},
//!                         "methods":{"safe":46,"unsafe_":43}},
//!                     },
//!                     "forbids_unsafe":false
//!                 }
//!             }
//!         }
//!     ]
//! }
//! ```
//!
//! The target of this module is to make it easy to extract the data in the schema;
//! In general this is achieved by a `total` method that allows for aggregating
//! for example used+unused, and at a lower level safe+unsafe_.

use std::{
    collections::HashMap,
    ops::Add,
    process::{Command, Stdio},
};

use cargo_metadata::CargoOpt;
use serde::Deserialize;

use crate::{errors::GeigerError, ManifestPath, NameVersion};

/// A client used to evaluate `cargo-geiger` information for some package
/// and its dependencies
#[derive(Debug)]
pub struct GeigerClient {
    #[cfg(test)]
    output: GeigerOutput,
    unsafety: HashMap<NameVersion, GeigerUnsafety>,
}

impl GeigerClient {
    /// Creates a new client from the path one would pass to `cargo-geiger`
    ///
    /// Requires that `cargo-geiger` is installed on the system. The caller must
    /// also check that `features` is a valid combination, otherwise `cargo-
    /// geiger` may fail. An empty vector will be handled as default features.
    ///
    /// Will create an absolute path of `manifest_path`.
    ///
    /// This can be very slow, especially if the package has not been parsed
    /// before. Therefore, it is often better to do this lazily (i.e. wrapping
    /// in a [`Lazy`](once_cell::sync::Lazy)).
    ///
    /// Will redirect both `stdout` and `stderr` internally.
    ///
    /// # Errors
    ///
    /// If `cargo-geiger` fails in a way that is not due to it not being
    /// installed, an error variant will be returned. Possible faults may be
    /// compilation errors, missing libraries for compilation, erroneous
    /// feature combinations etc.
    ///
    /// # Panics
    ///
    /// Panics if `cargo-geiger` is not installed and available in `$PATH`
    pub fn new(
        manifest_path: &ManifestPath,
        features: Vec<CargoOpt>,
    ) -> Result<Self, Box<GeigerError>> {
        let mut cmd = Command::new("cargo-geiger");
        cmd.args(["--output-format", "Json"])
            .arg("--quiet") // Only output tree
            .arg("--manifest-path")
            .arg(manifest_path.as_path());

        for f in features {
            // Validity of these should be checked by CLI, not library
            match f {
                CargoOpt::AllFeatures => {
                    cmd.arg("--all-features");
                }
                CargoOpt::NoDefaultFeatures => {
                    cmd.arg("--no-default-features");
                }
                CargoOpt::SomeFeatures(s) => {
                    if !s.is_empty() {
                        cmd.arg("--features");
                        cmd.args(s);
                    }
                }
            }
        }

        let output = cmd
            .stdin(Stdio::null())
            .output()
            .unwrap_or_else(|e| {
                panic!(
                    "geiger command failed to start with error: {e}, are you sure `cargo-geiger` is installed?"
                )
            });

        if !output.status.success() {
            // Geiger gives error codes even if its only errors codes...
            // We let this explode somewhere else
            println!("cargo-geiger exited with non-zero exit code, but it was ignored");
            eprintln!("stderr: {}", String::from_utf8_lossy(&output.stderr));
            // return Err(Box::new(GeigerError::NonZeroStatus(
            //     output.status.code().unwrap_or(-1),
            //     stderr.to_string(),
            // )));
        }

        let stdout = String::from_utf8_lossy(&output.stdout);
        let res = Self::from_json(&stdout);
        match res {
            Ok(s) => Ok(s),
            Err(e) => Err(Box::new(GeigerError::UnexpectedOutput(
                e.to_string(),
                stdout.to_string(),
            ))),
        }
    }

    /// Parse [`GeigerOutput`] from a JSON string (i.e. the output of
    /// `cargo-geiger` when run with `--output-format Json`)
    ///
    /// # Errors
    ///
    /// If the `cargo-geiger` output cannot be deserialized, an error variant
    /// will be returned containing the information from `serde`.
    pub fn from_json(geiger_output: &str) -> Result<Self, serde_json::Error> {
        let output = serde_json::from_str::<GeigerOutput>(geiger_output)?;
        Ok(Self::from(output))
    }

    #[must_use]
    pub fn unsafety(&self, gid: &NameVersion) -> Option<GeigerUnsafety> {
        self.unsafety.get(gid).copied()
    }
}

impl From<GeigerOutput> for GeigerClient {
    fn from(value: GeigerOutput) -> Self {
        let mut unsafety = HashMap::with_capacity(value.packages.len());
        for p in &value.packages {
            unsafety.insert(p.package.id.clone(), p.unsafety);
        }
        Self {
            #[cfg(test)]
            output: value,
            unsafety,
        }
    }
}

/// Calculates a percentage, rounded to two
/// decimal points
///
/// This function will handle `0 / 0` to be equal to `0.0` (all code is safe,
/// there is no code).
#[must_use]
pub(crate) fn two_digit_percentage(part: u32, total: u32) -> f64 {
    let res = f64::from(part) / f64::from(total);
    if res.is_finite() {
        // We only really care about at most two decimal points
        (res * 10000.0).round() / 100.0
    } else {
        0.0
    }
}

/// The full output of `cargo-geiger`
#[derive(Debug, Clone, Deserialize, Default)]
pub struct GeigerOutput {
    pub packages: Vec<GeigerPackageOutput>,
}

#[derive(Debug, Clone, Deserialize)]
pub struct GeigerPackageOutput {
    pub package: GeigerPackage,
    pub unsafety: GeigerUnsafety,
}

/// A package in `cargo-geiger` used to identify what has been parsed
#[derive(Debug, Clone, Deserialize)]
pub struct GeigerPackage {
    pub id: NameVersion,
    // Other fields ignored
}

/// The output of `cargo-geiger` for one package/dependency
///
/// Corresponds to the object named "unsafety" in a `cargo-geiger` output.
/// `used` and `unused` refers to if the code is used by the package used
/// to provide the Geiger data. A package may have a high unsafe usage, but
/// nothing is used by the analyzed package.
#[derive(Debug, Clone, Copy, Deserialize)]
pub struct GeigerUnsafety {
    pub used: GeigerCategories,
    pub unused: GeigerCategories,
    pub forbids_unsafe: bool,
}

impl GeigerUnsafety {
    /// Retrieves the total geiger count for all targets, i.e. total for used
    /// and unused code
    #[must_use]
    pub fn total(&self) -> GeigerCategories {
        GeigerCategories {
            functions: self.used.functions + self.unused.functions,
            exprs: self.used.exprs + self.unused.exprs,
            item_impls: self.used.item_impls + self.unused.item_impls,
            item_traits: self.used.item_traits + self.unused.item_traits,
            methods: self.used.methods + self.unused.methods,
        }
    }

    #[must_use]
    pub fn used_safe(&self) -> u32 {
        self.used.total_safe()
    }

    #[must_use]
    pub fn used_unsafe(&self) -> u32 {
        self.used.total_unsafe()
    }

    #[must_use]
    pub fn unused_safe(&self) -> u32 {
        self.unused.total_safe()
    }

    #[must_use]
    pub fn unused_unsafe(&self) -> u32 {
        self.unused.total_unsafe()
    }

    #[must_use]
    pub fn total_safe(&self) -> u32 {
        self.used_safe() + self.unused_safe()
    }

    #[must_use]
    pub fn total_unsafe(&self) -> u32 {
        self.used_unsafe() + self.unused_unsafe()
    }

    /// Calculates the percentage of the package to be unsafe, to two decimal
    /// points
    ///
    /// Uses the total unsafe and total safe code as basis.
    #[must_use]
    pub fn percentage_unsafe(&self) -> f64 {
        two_digit_percentage(
            self.total_unsafe(),
            self.total_safe() + self.total_unsafe(),
        )
    }
}

/// All different targets in Rust code that `cargo-geiger` counts
#[derive(Debug, Clone, Copy, Deserialize)]
pub struct GeigerCategories {
    pub functions: GeigerCount,
    pub exprs: GeigerCount,
    pub item_impls: GeigerCount,
    pub item_traits: GeigerCount,
    pub methods: GeigerCount,
}

impl GeigerCategories {
    /// Aggregates all [`GeigerCount`] for all categories, returning one with
    /// total safe and total unsafe for all categories
    #[must_use]
    pub fn total(&self) -> GeigerCount {
        self.functions
            + self.exprs
            + self.item_impls
            + self.item_traits
            + self.methods
    }

    #[must_use]
    pub fn total_safe(&self) -> u32 {
        self.functions.safe
            + self.exprs.safe
            + self.item_impls.safe
            + self.item_traits.safe
            + self.methods.safe
    }

    #[must_use]
    pub fn total_unsafe(&self) -> u32 {
        self.functions.unsafe_
            + self.exprs.unsafe_
            + self.item_impls.unsafe_
            + self.item_traits.unsafe_
            + self.methods.unsafe_
    }
}

impl Add<GeigerCategories> for GeigerCategories {
    type Output = GeigerCategories;

    fn add(self, rhs: GeigerCategories) -> Self::Output {
        GeigerCategories {
            functions: self.functions + rhs.functions,
            exprs: self.exprs + rhs.exprs,
            item_impls: self.item_impls + rhs.item_impls,
            item_traits: self.item_traits + rhs.item_traits,
            methods: self.methods + rhs.methods,
        }
    }
}

/// The safety stats for a package analyzed by `cargo-geiger`,
/// i.e. counts for lines of safe and unsafe code
#[derive(Debug, Clone, Copy, PartialEq, Eq, Deserialize)]
pub struct GeigerCount {
    pub safe: u32,
    pub unsafe_: u32,
}

impl GeigerCount {
    /// The total amount of counts made by Geiger
    #[must_use]
    pub fn total(&self) -> u32 {
        self.safe + self.unsafe_
    }

    /// Calculate the percentage of the count that is unsafe to two digits
    /// precisions
    #[must_use]
    pub fn percentage_unsafe(&self) -> f64 {
        two_digit_percentage(self.unsafe_, self.total())
    }
}

impl Add<GeigerCount> for GeigerCount {
    type Output = GeigerCount;

    fn add(self, rhs: GeigerCount) -> Self::Output {
        GeigerCount {
            safe: self.safe + rhs.safe,
            unsafe_: self.unsafe_ + rhs.unsafe_,
        }
    }
}

#[cfg(test)]
mod test {
    use std::{fs, path::Path};

    use test_case::test_case;

    use crate::{geiger::GeigerCount, ManifestPath};

    use super::{GeigerClient, GeigerOutput};

    #[test_case(0, 0 => 0.0)]
    #[test_case(3, 1 => 25.0)]
    #[test_case(9, 1 => 10.0)]
    #[test_case(2, 1 => 33.33)]
    fn two_digit_percentage(safe_count: u32, unsafe_count: u32) -> f64 {
        super::two_digit_percentage(unsafe_count, safe_count + unsafe_count)
    }

    #[test_case("simple_deps")]
    #[test_case("known_advisory_deps")]
    #[test_case("feature_deps")]
    #[test_case("forbids_unsafe")]
    fn geiger_from_path(crate_name: &'static str) {
        let path_string =
            format!("test_data/fake_crates/{crate_name}/Cargo.toml");
        let path = ManifestPath::from(path_string);
        GeigerClient::new(&path, vec![]).unwrap();
    }

    #[test_case("simple_deps")]
    fn deserialize_geiger_output_smoke_test(crate_name: &'static str) {
        let path_string = format!("test_data/geiger-output/{crate_name}.json");
        let path = Path::new(&path_string);
        let json_string = fs::read_to_string(path).unwrap();
        serde_json::from_str::<GeigerOutput>(&json_string).unwrap();
    }

    #[test_case(0, 0, 0, 0)]
    #[test_case(1, 1, 0, 0)]
    #[test_case(1, 2, 3, 4)]
    fn add_geiger_counts(safe0: u32, unsafe0: u32, safe1: u32, unsafe1: u32) {
        let gc0 = GeigerCount {
            safe: safe0,
            unsafe_: unsafe0,
        };
        let gc1 = GeigerCount {
            safe: safe1,
            unsafe_: unsafe1,
        };
        let gc_res = GeigerCount {
            safe: safe0 + safe1,
            unsafe_: unsafe0 + unsafe1,
        };
        assert_eq!(gc0 + gc1, gc_res);
    }
}