// Copyright 2017 Google Inc.
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT.

use std::io::{stderr, Write};
use std::path::PathBuf;

use super::glob::Pattern;
use super::{Matcher, MatcherIO, WalkEntry};

fn read_link_target(file_info: &WalkEntry) -> Option<PathBuf> {
    match file_info.path().read_link() {
        Ok(target) => Some(target),
        Err(err) => {
            // If it's not a symlink, then it's not an error that should be
            // shown.
            if err.kind() != std::io::ErrorKind::InvalidInput {
                writeln!(
                    &mut stderr(),
                    "Error reading target of {}: {}",
                    file_info.path().display(),
                    err
                )
                .unwrap();
            }

            None
        }
    }
}

/// This matcher makes a comparison of the link target against a shell wildcard
/// pattern. See `glob::Pattern` for details on the exact syntax.
pub struct LinkNameMatcher {
    pattern: Pattern,
}

impl LinkNameMatcher {
    pub fn new(pattern_string: &str, caseless: bool) -> LinkNameMatcher {
        let pattern = Pattern::new(pattern_string, caseless);
        Self { pattern }
    }
}

impl Matcher for LinkNameMatcher {
    fn matches(&self, file_info: &WalkEntry, _: &mut MatcherIO) -> bool {
        if let Some(target) = read_link_target(file_info) {
            self.pattern.matches(&target.to_string_lossy())
        } else {
            false
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::find::matchers::tests::get_dir_entry_for;
    use crate::find::tests::FakeDependencies;

    use std::io::ErrorKind;

    #[cfg(unix)]
    use std::os::unix::fs::symlink;
    #[cfg(windows)]
    use std::os::windows::fs::symlink_file;

    fn create_file_link() {
        #[cfg(unix)]
        if let Err(e) = symlink("abbbc", "test_data/links/link-f") {
            assert!(
                e.kind() == ErrorKind::AlreadyExists,
                "Failed to create sym link: {e:?}"
            );
        }
        #[cfg(windows)]
        if let Err(e) = symlink_file("abbbc", "test_data/links/link-f") {
            assert!(
                e.kind() == ErrorKind::AlreadyExists,
                "Failed to create sym link: {:?}",
                e
            );
        }
    }

    #[test]
    fn matches_against_link_target() {
        create_file_link();

        let link_f = get_dir_entry_for("test_data/links", "link-f");
        let matcher = LinkNameMatcher::new("ab?bc", false);
        let deps = FakeDependencies::new();
        assert!(matcher.matches(&link_f, &mut deps.new_matcher_io()));
    }

    #[test]
    fn caseless_matches_against_link_target() {
        create_file_link();

        let link_f = get_dir_entry_for("test_data/links", "link-f");
        let matcher = LinkNameMatcher::new("AbB?c", true);
        let deps = FakeDependencies::new();
        assert!(matcher.matches(&link_f, &mut deps.new_matcher_io()));
    }
}
