// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! lint on multiple versions of a crate being used

use crate::rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
use crate::rustc::{declare_tool_lint, lint_array};
use crate::syntax::{ast::*, source_map::DUMMY_SP};
use crate::utils::span_lint;

use cargo_metadata;
use itertools::Itertools;

/// **What it does:** Checks to see if multiple versions of a crate are being
/// used.
///
/// **Why is this bad?** This bloats the size of targets, and can lead to
/// confusing error messages when structs or traits are used interchangeably
/// between different versions of a crate.
///
/// **Known problems:** Because this can be caused purely by the dependencies
/// themselves, it's not always possible to fix this issue.
///
/// **Example:**
/// ```toml
/// # This will pull in both winapi v0.3.4 and v0.2.8, triggering a warning.
/// [dependencies]
/// ctrlc = "3.1.0"
/// ansi_term = "0.11.0"
/// ```
declare_clippy_lint! {
    pub MULTIPLE_CRATE_VERSIONS,
    cargo,
    "multiple versions of the same crate being used"
}

pub struct Pass;

impl LintPass for Pass {
    fn get_lints(&self) -> LintArray {
        lint_array!(MULTIPLE_CRATE_VERSIONS)
    }
}

impl EarlyLintPass for Pass {
    fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &Crate) {
        let metadata = if let Ok(metadata) = cargo_metadata::metadata_deps(None, true) {
            metadata
        } else {
            span_lint(cx, MULTIPLE_CRATE_VERSIONS, krate.span, "could not read cargo metadata");

            return;
        };

        let mut packages = metadata.packages;
        packages.sort_by(|a, b| a.name.cmp(&b.name));

        for (name, group) in &packages.into_iter().group_by(|p| p.name.clone()) {
            let group: Vec<cargo_metadata::Package> = group.collect();

            if group.len() > 1 {
                let versions = group.into_iter().map(|p| p.version).join(", ");

                span_lint(
                    cx,
                    MULTIPLE_CRATE_VERSIONS,
                    DUMMY_SP,
                    &format!("multiple versions for dependency `{}`: {}", name, versions),
                );
            }
        }
    }
}