use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
use std::path::{Path, PathBuf};
use std::sync::Arc;
use std::{env, fs};

use crate::core::compiler::{CompileKind, DefaultExecutor, Executor, UnitOutput};
use crate::core::{
    Dependency, Edition, Package, PackageId, PackageIdSpec, Source, SourceId, Target, Workspace,
};
use crate::ops::{common_for_install_and_uninstall::*, FilterRule};
use crate::ops::{CompileFilter, Packages};
use crate::sources::{GitSource, PathSource, SourceConfigMap};
use crate::util::errors::CargoResult;
use crate::util::{Config, Filesystem, Rustc, ToSemver, VersionReqExt};
use crate::{drop_println, ops};

use anyhow::{bail, format_err, Context as _};
use cargo_util::paths;
use itertools::Itertools;
use semver::VersionReq;
use tempfile::Builder as TempFileBuilder;

struct Transaction {
    bins: Vec<PathBuf>,
}

impl Transaction {
    fn success(mut self) {
        self.bins.clear();
    }
}

impl Drop for Transaction {
    fn drop(&mut self) {
        for bin in self.bins.iter() {
            let _ = paths::remove_file(bin);
        }
    }
}

struct InstallablePackage<'cfg, 'a> {
    config: &'cfg Config,
    opts: ops::CompileOptions,
    root: Filesystem,
    source_id: SourceId,
    vers: Option<&'a str>,
    force: bool,
    no_track: bool,

    pkg: Package,
    ws: Workspace<'cfg>,
    rustc: Rustc,
    target: String,
}

impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
    // Returns pkg to install. None if pkg is already installed
    pub fn new(
        config: &'cfg Config,
        root: Filesystem,
        map: SourceConfigMap<'_>,
        krate: Option<&str>,
        source_id: SourceId,
        from_cwd: bool,
        vers: Option<&'a str>,
        original_opts: &'a ops::CompileOptions,
        force: bool,
        no_track: bool,
        needs_update_if_source_is_index: bool,
    ) -> CargoResult<Option<InstallablePackage<'cfg, 'a>>> {
        if let Some(name) = krate {
            if name == "." {
                bail!(
                    "To install the binaries for the package in current working \
                     directory use `cargo install --path .`. \n\
                     Use `cargo build` if you want to simply build the package."
                )
            }
        }

        let dst = root.join("bin").into_path_unlocked();
        let pkg = {
            let dep = {
                if let Some(krate) = krate {
                    let vers = if let Some(vers_flag) = vers {
                        Some(parse_semver_flag(vers_flag)?.to_string())
                    } else if source_id.is_registry() {
                        // Avoid pre-release versions from crate.io
                        // unless explicitly asked for
                        Some(String::from("*"))
                    } else {
                        None
                    };
                    Some(Dependency::parse(krate, vers.as_deref(), source_id)?)
                } else {
                    None
                }
            };

            if source_id.is_git() {
                let mut source = GitSource::new(source_id, config)?;
                select_pkg(
                    &mut source,
                    dep,
                    |git: &mut GitSource<'_>| git.read_packages(),
                    config,
                )?
            } else if source_id.is_path() {
                let mut src = path_source(source_id, config)?;
                if !src.path().is_dir() {
                    bail!(
                        "`{}` is not a directory. \
                     --path must point to a directory containing a Cargo.toml file.",
                        src.path().display()
                    )
                }
                if !src.path().join("Cargo.toml").exists() {
                    if from_cwd {
                        bail!(
                            "`{}` is not a crate root; specify a crate to \
                         install from crates.io, or use --path or --git to \
                         specify an alternate source",
                            src.path().display()
                        );
                    } else if src.path().join("cargo.toml").exists() {
                        bail!(
                            "`{}` does not contain a Cargo.toml file, but found cargo.toml please try to rename it to Cargo.toml. \
                     --path must point to a directory containing a Cargo.toml file.",
                            src.path().display()
                        )
                    } else {
                        bail!(
                            "`{}` does not contain a Cargo.toml file. \
                     --path must point to a directory containing a Cargo.toml file.",
                            src.path().display()
                        )
                    }
                }
                select_pkg(
                    &mut src,
                    dep,
                    |path: &mut PathSource<'_>| path.read_packages(),
                    config,
                )?
            } else if let Some(dep) = dep {
                let mut source = map.load(source_id, &HashSet::new())?;
                if let Ok(Some(pkg)) = installed_exact_package(
                    dep.clone(),
                    &mut source,
                    config,
                    original_opts,
                    &root,
                    &dst,
                    force,
                ) {
                    let msg = format!(
                        "package `{}` is already installed, use --force to override",
                        pkg
                    );
                    config.shell().status("Ignored", &msg)?;
                    return Ok(None);
                }
                select_dep_pkg(&mut source, dep, config, needs_update_if_source_is_index)?
            } else {
                bail!(
                    "must specify a crate to install from \
                         crates.io, or use --path or --git to \
                         specify alternate source"
                )
            }
        };

        let (ws, rustc, target) =
            make_ws_rustc_target(config, &original_opts, &source_id, pkg.clone())?;
        // If we're installing in --locked mode and there's no `Cargo.lock` published
        // ie. the bin was published before https://github.com/rust-lang/cargo/pull/7026
        if config.locked() && !ws.root().join("Cargo.lock").exists() {
            config.shell().warn(format!(
                "no Cargo.lock file published in {}",
                pkg.to_string()
            ))?;
        }
        let pkg = if source_id.is_git() {
            // Don't use ws.current() in order to keep the package source as a git source so that
            // install tracking uses the correct source.
            pkg
        } else {
            ws.current()?.clone()
        };

        // When we build this package, we want to build the *specified* package only,
        // and avoid building e.g. workspace default-members instead. Do so by constructing
        // specialized compile options specific to the identified package.
        // See test `path_install_workspace_root_despite_default_members`.
        let mut opts = original_opts.clone();
        // For cargo install tracking, we retain the source git url in `pkg`, but for the build spec
        // we need to unconditionally use `ws.current()` to correctly address the path where we
        // locally cloned that repo.
        let pkgidspec = PackageIdSpec::from_package_id(ws.current()?.package_id());
        opts.spec = Packages::Packages(vec![pkgidspec.to_string()]);

        if from_cwd {
            if pkg.manifest().edition() == Edition::Edition2015 {
                config.shell().warn(
                    "Using `cargo install` to install the binaries for the \
                     package in current working directory is deprecated, \
                     use `cargo install --path .` instead. \
                     Use `cargo build` if you want to simply build the package.",
                )?
            } else {
                bail!(
                    "Using `cargo install` to install the binaries for the \
                     package in current working directory is no longer supported, \
                     use `cargo install --path .` instead. \
                     Use `cargo build` if you want to simply build the package."
                )
            }
        };

        // For bare `cargo install` (no `--bin` or `--example`), check if there is
        // *something* to install. Explicit `--bin` or `--example` flags will be
        // checked at the start of `compile_ws`.
        if !opts.filter.is_specific() && !pkg.targets().iter().any(|t| t.is_bin()) {
            bail!(
                "there is nothing to install in `{}`, because it has no binaries\n\
                 `cargo install` is only for installing programs, and can't be used with libraries.\n\
                 To use a library crate, add it as a dependency to a Cargo project with `cargo add`.",
                pkg,
            );
        }

        let ip = InstallablePackage {
            config,
            opts,
            root,
            source_id,
            vers,
            force,
            no_track,

            pkg,
            ws,
            rustc,
            target,
        };

        // WARNING: no_track does not perform locking, so there is no protection
        // of concurrent installs.
        if no_track {
            // Check for conflicts.
            ip.no_track_duplicates(&dst)?;
        } else if is_installed(
            &ip.pkg, config, &ip.opts, &ip.rustc, &ip.target, &ip.root, &dst, force,
        )? {
            let msg = format!(
                "package `{}` is already installed, use --force to override",
                ip.pkg
            );
            config.shell().status("Ignored", &msg)?;
            return Ok(None);
        }

        Ok(Some(ip))
    }

    fn no_track_duplicates(&self, dst: &Path) -> CargoResult<BTreeMap<String, Option<PackageId>>> {
        // Helper for --no-track flag to make sure it doesn't overwrite anything.
        let duplicates: BTreeMap<String, Option<PackageId>> =
            exe_names(&self.pkg, &self.opts.filter)
                .into_iter()
                .filter(|name| dst.join(name).exists())
                .map(|name| (name, None))
                .collect();
        if !self.force && !duplicates.is_empty() {
            let mut msg: Vec<String> = duplicates
                .iter()
                .map(|(name, _)| {
                    format!(
                        "binary `{}` already exists in destination `{}`",
                        name,
                        dst.join(name).to_string_lossy()
                    )
                })
                .collect();
            msg.push("Add --force to overwrite".to_string());
            bail!("{}", msg.join("\n"));
        }
        Ok(duplicates)
    }

    fn install_one(mut self) -> CargoResult<bool> {
        self.config.shell().status("Installing", &self.pkg)?;

        let dst = self.root.join("bin").into_path_unlocked();

        let mut td_opt = None;
        let mut needs_cleanup = false;
        if !self.source_id.is_path() {
            let target_dir = if let Some(dir) = self.config.target_dir()? {
                dir
            } else if let Ok(td) = TempFileBuilder::new().prefix("cargo-install").tempdir() {
                let p = td.path().to_owned();
                td_opt = Some(td);
                Filesystem::new(p)
            } else {
                needs_cleanup = true;
                Filesystem::new(self.config.cwd().join("target-install"))
            };
            self.ws.set_target_dir(target_dir);
        }

        self.check_yanked_install()?;

        let exec: Arc<dyn Executor> = Arc::new(DefaultExecutor);
        let compile = ops::compile_ws(&self.ws, &self.opts, &exec).with_context(|| {
            if let Some(td) = td_opt.take() {
                // preserve the temporary directory, so the user can inspect it
                drop(td.into_path());
            }

            format!(
                "failed to compile `{}`, intermediate artifacts can be \
                 found at `{}`.\nTo reuse those artifacts with a future \
                 compilation, set the environment variable \
                 `CARGO_TARGET_DIR` to that path.",
                self.pkg,
                self.ws.target_dir().display()
            )
        })?;
        let mut binaries: Vec<(&str, &Path)> = compile
            .binaries
            .iter()
            .map(|UnitOutput { path, .. }| {
                let name = path.file_name().unwrap();
                if let Some(s) = name.to_str() {
                    Ok((s, path.as_ref()))
                } else {
                    bail!("Binary `{:?}` name can't be serialized into string", name)
                }
            })
            .collect::<CargoResult<_>>()?;
        if binaries.is_empty() {
            // Cargo already warns the user if they use a target specifier that matches nothing,
            // but we want to error if the user asked for a _particular_ binary to be installed,
            // and we didn't end up installing it.
            //
            // NOTE: This _should_ be impossible to hit since --bin=does_not_exist will fail on
            // target selection, and --bin=requires_a without --features=a will fail with "target
            // .. requires the features ..". But rather than assume that's the case, we define the
            // behavior for this fallback case as well.
            if let CompileFilter::Only { bins, examples, .. } = &self.opts.filter {
                let mut any_specific = false;
                if let FilterRule::Just(ref v) = bins {
                    if !v.is_empty() {
                        any_specific = true;
                    }
                }
                if let FilterRule::Just(ref v) = examples {
                    if !v.is_empty() {
                        any_specific = true;
                    }
                }
                if any_specific {
                    bail!("no binaries are available for install using the selected features");
                }
            }

            // If there _are_ binaries available, but none were selected given the current set of
            // features, let the user know.
            //
            // Note that we know at this point that _if_ bins or examples is set to `::Just`,
            // they're `::Just([])`, which is `FilterRule::none()`.
            let binaries: Vec<_> = self
                .pkg
                .targets()
                .iter()
                .filter(|t| t.is_executable())
                .collect();
            if !binaries.is_empty() {
                self.config
                    .shell()
                    .warn(make_warning_about_missing_features(&binaries))?;
            }

            return Ok(false);
        }
        // This is primarily to make testing easier.
        binaries.sort_unstable();

        let (tracker, duplicates) = if self.no_track {
            (None, self.no_track_duplicates(&dst)?)
        } else {
            let tracker = InstallTracker::load(self.config, &self.root)?;
            let (_freshness, duplicates) = tracker.check_upgrade(
                &dst,
                &self.pkg,
                self.force,
                &self.opts,
                &self.target,
                &self.rustc.verbose_version,
            )?;
            (Some(tracker), duplicates)
        };

        paths::create_dir_all(&dst)?;

        // Copy all binaries to a temporary directory under `dst` first, catching
        // some failure modes (e.g., out of space) before touching the existing
        // binaries. This directory will get cleaned up via RAII.
        let staging_dir = TempFileBuilder::new()
            .prefix("cargo-install")
            .tempdir_in(&dst)?;
        for &(bin, src) in binaries.iter() {
            let dst = staging_dir.path().join(bin);
            // Try to move if `target_dir` is transient.
            if !self.source_id.is_path() && fs::rename(src, &dst).is_ok() {
                continue;
            }
            paths::copy(src, &dst)?;
        }

        let (to_replace, to_install): (Vec<&str>, Vec<&str>) = binaries
            .iter()
            .map(|&(bin, _)| bin)
            .partition(|&bin| duplicates.contains_key(bin));

        let mut installed = Transaction { bins: Vec::new() };
        let mut successful_bins = BTreeSet::new();

        // Move the temporary copies into `dst` starting with new binaries.
        for bin in to_install.iter() {
            let src = staging_dir.path().join(bin);
            let dst = dst.join(bin);
            self.config.shell().status("Installing", dst.display())?;
            fs::rename(&src, &dst).with_context(|| {
                format!("failed to move `{}` to `{}`", src.display(), dst.display())
            })?;
            installed.bins.push(dst);
            successful_bins.insert(bin.to_string());
        }

        // Repeat for binaries which replace existing ones but don't pop the error
        // up until after updating metadata.
        let replace_result = {
            let mut try_install = || -> CargoResult<()> {
                for &bin in to_replace.iter() {
                    let src = staging_dir.path().join(bin);
                    let dst = dst.join(bin);
                    self.config.shell().status("Replacing", dst.display())?;
                    fs::rename(&src, &dst).with_context(|| {
                        format!("failed to move `{}` to `{}`", src.display(), dst.display())
                    })?;
                    successful_bins.insert(bin.to_string());
                }
                Ok(())
            };
            try_install()
        };

        if let Some(mut tracker) = tracker {
            tracker.mark_installed(
                &self.pkg,
                &successful_bins,
                self.vers.map(|s| s.to_string()),
                &self.opts,
                &self.target,
                &self.rustc.verbose_version,
            );

            if let Err(e) =
                remove_orphaned_bins(&self.ws, &mut tracker, &duplicates, &self.pkg, &dst)
            {
                // Don't hard error on remove.
                self.config
                    .shell()
                    .warn(format!("failed to remove orphan: {:?}", e))?;
            }

            match tracker.save() {
                Err(err) => replace_result.with_context(|| err)?,
                Ok(_) => replace_result?,
            }
        }

        // Reaching here means all actions have succeeded. Clean up.
        installed.success();
        if needs_cleanup {
            // Don't bother grabbing a lock as we're going to blow it all away
            // anyway.
            let target_dir = self.ws.target_dir().into_path_unlocked();
            paths::remove_dir_all(&target_dir)?;
        }

        // Helper for creating status messages.
        fn executables<T: AsRef<str>>(mut names: impl Iterator<Item = T> + Clone) -> String {
            if names.clone().count() == 1 {
                format!("(executable `{}`)", names.next().unwrap().as_ref())
            } else {
                format!(
                    "(executables {})",
                    names
                        .map(|b| format!("`{}`", b.as_ref()))
                        .collect::<Vec<_>>()
                        .join(", ")
                )
            }
        }

        if duplicates.is_empty() {
            self.config.shell().status(
                "Installed",
                format!(
                    "package `{}` {}",
                    self.pkg,
                    executables(successful_bins.iter())
                ),
            )?;
            Ok(true)
        } else {
            if !to_install.is_empty() {
                self.config.shell().status(
                    "Installed",
                    format!("package `{}` {}", self.pkg, executables(to_install.iter())),
                )?;
            }
            // Invert the duplicate map.
            let mut pkg_map = BTreeMap::new();
            for (bin_name, opt_pkg_id) in &duplicates {
                let key =
                    opt_pkg_id.map_or_else(|| "unknown".to_string(), |pkg_id| pkg_id.to_string());
                pkg_map.entry(key).or_insert_with(Vec::new).push(bin_name);
            }
            for (pkg_descr, bin_names) in &pkg_map {
                self.config.shell().status(
                    "Replaced",
                    format!(
                        "package `{}` with `{}` {}",
                        pkg_descr,
                        self.pkg,
                        executables(bin_names.iter())
                    ),
                )?;
            }
            Ok(true)
        }
    }

    fn check_yanked_install(&self) -> CargoResult<()> {
        if self.ws.ignore_lock() || !self.ws.root().join("Cargo.lock").exists() {
            return Ok(());
        }
        // It would be best if `source` could be passed in here to avoid a
        // duplicate "Updating", but since `source` is taken by value, then it
        // wouldn't be available for `compile_ws`.
        let (pkg_set, resolve) = ops::resolve_ws(&self.ws)?;
        ops::check_yanked(
            self.ws.config(),
            &pkg_set,
            &resolve,
            "consider running without --locked",
        )
    }
}

fn make_warning_about_missing_features(binaries: &[&Target]) -> String {
    let max_targets_listed = 7;
    let target_features_message = binaries
        .iter()
        .take(max_targets_listed)
        .map(|b| {
            let name = b.description_named();
            let features = b
                .required_features()
                .unwrap_or(&Vec::new())
                .iter()
                .map(|f| format!("`{f}`"))
                .join(", ");
            format!("  {name} requires the features: {features}")
        })
        .join("\n");

    let additional_bins_message = if binaries.len() > max_targets_listed {
        format!(
            "\n{} more targets also requires features not enabled. See them in the Cargo.toml file.",
            binaries.len() - max_targets_listed
        )
    } else {
        "".into()
    };

    let example_features = binaries[0]
        .required_features()
        .map(|f| f.join(" "))
        .unwrap_or_default();

    format!(
        "\
none of the package's binaries are available for install using the selected features
{target_features_message}{additional_bins_message}
Consider enabling some of the needed features by passing, e.g., `--features=\"{example_features}\"`"
    )
}

pub fn install(
    config: &Config,
    root: Option<&str>,
    krates: Vec<(&str, Option<&str>)>,
    source_id: SourceId,
    from_cwd: bool,
    opts: &ops::CompileOptions,
    force: bool,
    no_track: bool,
) -> CargoResult<()> {
    let root = resolve_root(root, config)?;
    let dst = root.join("bin").into_path_unlocked();
    let map = SourceConfigMap::new(config)?;

    let (installed_anything, scheduled_error) = if krates.len() <= 1 {
        let (krate, vers) = krates
            .into_iter()
            .next()
            .map(|(k, v)| (Some(k), v))
            .unwrap_or((None, None));
        let installable_pkg = InstallablePackage::new(
            config, root, map, krate, source_id, from_cwd, vers, opts, force, no_track, true,
        )?;
        let mut installed_anything = true;
        if let Some(installable_pkg) = installable_pkg {
            installed_anything = installable_pkg.install_one()?;
        }
        (installed_anything, false)
    } else {
        let mut succeeded = vec![];
        let mut failed = vec![];
        // "Tracks whether or not the source (such as a registry or git repo) has been updated.
        // This is used to avoid updating it multiple times when installing multiple crates.
        let mut did_update = false;

        let pkgs_to_install: Vec<_> = krates
            .into_iter()
            .filter_map(|(krate, vers)| {
                let root = root.clone();
                let map = map.clone();
                match InstallablePackage::new(
                    config,
                    root,
                    map,
                    Some(krate),
                    source_id,
                    from_cwd,
                    vers,
                    opts,
                    force,
                    no_track,
                    !did_update,
                ) {
                    Ok(Some(installable_pkg)) => {
                        did_update = true;
                        Some((krate, installable_pkg))
                    }
                    Ok(None) => {
                        // Already installed
                        succeeded.push(krate);
                        None
                    }
                    Err(e) => {
                        crate::display_error(&e, &mut config.shell());
                        failed.push(krate);
                        // We assume an update was performed if we got an error.
                        did_update = true;
                        None
                    }
                }
            })
            .collect();

        let install_results: Vec<_> = pkgs_to_install
            .into_iter()
            .map(|(krate, installable_pkg)| (krate, installable_pkg.install_one()))
            .collect();

        for (krate, result) in install_results {
            match result {
                Ok(installed) => {
                    if installed {
                        succeeded.push(krate);
                    }
                }
                Err(e) => {
                    crate::display_error(&e, &mut config.shell());
                    failed.push(krate);
                }
            }
        }

        let mut summary = vec![];
        if !succeeded.is_empty() {
            summary.push(format!("Successfully installed {}!", succeeded.join(", ")));
        }
        if !failed.is_empty() {
            summary.push(format!(
                "Failed to install {} (see error(s) above).",
                failed.join(", ")
            ));
        }
        if !succeeded.is_empty() || !failed.is_empty() {
            config.shell().status("Summary", summary.join(" "))?;
        }

        (!succeeded.is_empty(), !failed.is_empty())
    };

    if installed_anything {
        // Print a warning that if this directory isn't in PATH that they won't be
        // able to run these commands.
        let path = config.get_env_os("PATH").unwrap_or_default();
        let dst_in_path = env::split_paths(&path).any(|path| path == dst);

        if !dst_in_path {
            config.shell().warn(&format!(
                "be sure to add `{}` to your PATH to be \
             able to run the installed binaries",
                dst.display()
            ))?;
        }
    }

    if scheduled_error {
        bail!("some crates failed to install");
    }

    Ok(())
}

fn is_installed(
    pkg: &Package,
    config: &Config,
    opts: &ops::CompileOptions,
    rustc: &Rustc,
    target: &str,
    root: &Filesystem,
    dst: &Path,
    force: bool,
) -> CargoResult<bool> {
    let tracker = InstallTracker::load(config, root)?;
    let (freshness, _duplicates) =
        tracker.check_upgrade(dst, pkg, force, opts, target, &rustc.verbose_version)?;
    Ok(freshness.is_fresh())
}

/// Checks if vers can only be satisfied by exactly one version of a package in a registry, and it's
/// already installed. If this is the case, we can skip interacting with a registry to check if
/// newer versions may be installable, as no newer version can exist.
fn installed_exact_package<T>(
    dep: Dependency,
    source: &mut T,
    config: &Config,
    opts: &ops::CompileOptions,
    root: &Filesystem,
    dst: &Path,
    force: bool,
) -> CargoResult<Option<Package>>
where
    T: Source,
{
    if !dep.version_req().is_exact() {
        // If the version isn't exact, we may need to update the registry and look for a newer
        // version - we can't know if the package is installed without doing so.
        return Ok(None);
    }
    // Try getting the package from the registry  without updating it, to avoid a potentially
    // expensive network call in the case that the package is already installed.
    // If this fails, the caller will possibly do an index update and try again, this is just a
    // best-effort check to see if we can avoid hitting the network.
    if let Ok(pkg) = select_dep_pkg(source, dep, config, false) {
        let (_ws, rustc, target) =
            make_ws_rustc_target(config, opts, &source.source_id(), pkg.clone())?;
        if let Ok(true) = is_installed(&pkg, config, opts, &rustc, &target, root, dst, force) {
            return Ok(Some(pkg));
        }
    }
    Ok(None)
}

fn make_ws_rustc_target<'cfg>(
    config: &'cfg Config,
    opts: &ops::CompileOptions,
    source_id: &SourceId,
    pkg: Package,
) -> CargoResult<(Workspace<'cfg>, Rustc, String)> {
    let mut ws = if source_id.is_git() || source_id.is_path() {
        Workspace::new(pkg.manifest_path(), config)?
    } else {
        Workspace::ephemeral(pkg, config, None, false)?
    };
    ws.set_ignore_lock(config.lock_update_allowed());
    ws.set_require_optional_deps(false);

    let rustc = config.load_global_rustc(Some(&ws))?;
    let target = match &opts.build_config.single_requested_kind()? {
        CompileKind::Host => rustc.host.as_str().to_owned(),
        CompileKind::Target(target) => target.short_name().to_owned(),
    };

    Ok((ws, rustc, target))
}

/// Parses x.y.z as if it were =x.y.z, and gives CLI-specific error messages in the case of invalid
/// values.
fn parse_semver_flag(v: &str) -> CargoResult<VersionReq> {
    // If the version begins with character <, >, =, ^, ~ parse it as a
    // version range, otherwise parse it as a specific version
    let first = v
        .chars()
        .next()
        .ok_or_else(|| format_err!("no version provided for the `--version` flag"))?;

    let is_req = "<>=^~".contains(first) || v.contains('*');
    if is_req {
        match v.parse::<VersionReq>() {
            Ok(v) => Ok(v),
            Err(_) => bail!(
                "the `--version` provided, `{}`, is \
                     not a valid semver version requirement\n\n\
                     Please have a look at \
                     https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html \
                     for the correct format",
                v
            ),
        }
    } else {
        match v.to_semver() {
            Ok(v) => Ok(VersionReq::exact(&v)),
            Err(e) => {
                let mut msg = format!(
                    "the `--version` provided, `{}`, is \
                         not a valid semver version: {}\n",
                    v, e
                );

                // If it is not a valid version but it is a valid version
                // requirement, add a note to the warning
                if v.parse::<VersionReq>().is_ok() {
                    msg.push_str(&format!(
                        "\nif you want to specify semver range, \
                             add an explicit qualifier, like ^{}",
                        v
                    ));
                }
                bail!(msg);
            }
        }
    }
}

/// Display a list of installed binaries.
pub fn install_list(dst: Option<&str>, config: &Config) -> CargoResult<()> {
    let root = resolve_root(dst, config)?;
    let tracker = InstallTracker::load(config, &root)?;
    for (k, v) in tracker.all_installed_bins() {
        drop_println!(config, "{}:", k);
        for bin in v {
            drop_println!(config, "    {}", bin);
        }
    }
    Ok(())
}

/// Removes executables that are no longer part of a package that was
/// previously installed.
fn remove_orphaned_bins(
    ws: &Workspace<'_>,
    tracker: &mut InstallTracker,
    duplicates: &BTreeMap<String, Option<PackageId>>,
    pkg: &Package,
    dst: &Path,
) -> CargoResult<()> {
    let filter = ops::CompileFilter::new_all_targets();
    let all_self_names = exe_names(pkg, &filter);
    let mut to_remove: HashMap<PackageId, BTreeSet<String>> = HashMap::new();
    // For each package that we stomped on.
    for other_pkg in duplicates.values().flatten() {
        // Only for packages with the same name.
        if other_pkg.name() == pkg.name() {
            // Check what the old package had installed.
            if let Some(installed) = tracker.installed_bins(*other_pkg) {
                // If the old install has any names that no longer exist,
                // add them to the list to remove.
                for installed_name in installed {
                    if !all_self_names.contains(installed_name.as_str()) {
                        to_remove
                            .entry(*other_pkg)
                            .or_default()
                            .insert(installed_name.clone());
                    }
                }
            }
        }
    }

    for (old_pkg, bins) in to_remove {
        tracker.remove(old_pkg, &bins);
        for bin in bins {
            let full_path = dst.join(bin);
            if full_path.exists() {
                ws.config().shell().status(
                    "Removing",
                    format!(
                        "executable `{}` from previous version {}",
                        full_path.display(),
                        old_pkg
                    ),
                )?;
                paths::remove_file(&full_path)
                    .with_context(|| format!("failed to remove {:?}", full_path))?;
            }
        }
    }
    Ok(())
}
