// Copyright Kitware, Inc.
//
// 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.

use derive_builder::Builder;
use git_checks_core::impl_prelude::*;

use crate::binary_format;

/// Checks whether a file's executable permissions matches its contents.
///
/// Files which look executable but are not marked as such or vice versa are rejected.
#[derive(Builder, Debug, Default, Clone)]
#[builder(field(private))]
pub struct CheckExecutablePermissions {
    #[builder(private)]
    #[builder(setter(name = "_extensions"))]
    #[builder(default)]
    extensions: Vec<String>,
}

impl CheckExecutablePermissionsBuilder {
    /// Extensions considered to indicate an executable file.
    ///
    /// Really only intended for Windows where executable permissions do not exist.
    ///
    /// Configuration: Optional
    /// Default: `Vec::new()`
    pub fn extensions<I>(&mut self, extensions: I) -> &mut Self
    where
        I: IntoIterator,
        I::Item: Into<String>,
    {
        self.extensions = Some(extensions.into_iter().map(Into::into).collect());
        self
    }
}

impl CheckExecutablePermissions {
    /// Create a new builder.
    pub fn builder() -> CheckExecutablePermissionsBuilder {
        CheckExecutablePermissionsBuilder::default()
    }
}

impl ContentCheck for CheckExecutablePermissions {
    fn name(&self) -> &str {
        "check-executable-permissions"
    }

    fn check(
        &self,
        ctx: &CheckGitContext,
        content: &dyn Content,
    ) -> Result<CheckResult, Box<dyn Error>> {
        let mut result = CheckResult::new();

        for diff in content.diffs() {
            match diff.status {
                StatusChange::Added | StatusChange::Modified(_) => (),
                _ => continue,
            }

            // Ignore files which haven't changed their modes.
            if diff.old_mode == diff.new_mode {
                continue;
            }

            let is_executable = match diff.new_mode.as_str() {
                "100755" => true,
                "100644" => false,
                _ => continue,
            };

            // LFS pointer files are defined as per its spec to have the same permission bit as the
            // content it points to. Since this check can only access the pointer content, it is
            // likely to be wrong here. Just ignore files specified to use the `lfs` filter.
            let filter_attr = ctx.check_attr("filter", diff.name.as_path())?;
            if let AttributeState::Value(filter_name) = filter_attr {
                if filter_name == "lfs" {
                    continue;
                }
            }

            let executable_ext = self
                .extensions
                .iter()
                .any(|ext| diff.name.as_str().ends_with(ext));
            let looks_executable = if executable_ext {
                true
            } else {
                let cat_file = ctx
                    .git()
                    .arg("cat-file")
                    .arg("blob")
                    .arg(diff.new_blob.as_str())
                    .output()
                    .map_err(|err| GitError::subcommand("cat-file", err))?;
                let content = &cat_file.stdout;
                let shebang = content.starts_with(b"#!/") || content.starts_with(b"#! /");
                if shebang {
                    true
                } else {
                    binary_format::detect_binary_format(content)
                        .map_or(false, |fmt| fmt.is_executable())
                }
            };

            let err = match (is_executable, looks_executable) {
                (true, false) => {
                    Some("with executable permissions, but the file does not look executable")
                },
                (false, true) => {
                    Some("without executable permissions, but the file looks executable")
                },
                _ => None,
            };

            if let Some(msg) = err {
                result.add_error(format!(
                    "{}adds `{}` {}.",
                    commit_prefix(content),
                    diff.name,
                    msg,
                ));
            }
        }

        Ok(result)
    }
}

#[cfg(feature = "config")]
pub(crate) mod config {
    use git_checks_config::{register_checks, CommitCheckConfig, IntoCheck, TopicCheckConfig};
    use serde::Deserialize;
    #[cfg(test)]
    use serde_json::json;

    use crate::CheckExecutablePermissions;

    /// Configuration for the `CheckExecutablePermissions` check.
    ///
    /// The `extensions` key is a list of strings, defaulting to an empty list. These extensions
    /// are used to detect executable files on Windows since other platforms can usually be
    /// detected by the file contents.
    ///
    /// This check is registered as a commit check with the name `"check_executable_permissions"
    /// and as a topic check with the name `"check_executable_permissions/topic"`.
    ///
    /// # Example
    ///
    /// ```json
    /// {
    ///     "extensions": [
    ///         "bat",
    ///         "exe",
    ///         "cmd"
    ///     ]
    /// }
    /// ```
    #[derive(Deserialize, Debug)]
    pub struct CheckExecutablePermissionsConfig {
        #[serde(default)]
        extensions: Option<Vec<String>>,
    }

    impl IntoCheck for CheckExecutablePermissionsConfig {
        type Check = CheckExecutablePermissions;

        fn into_check(self) -> Self::Check {
            let mut builder = CheckExecutablePermissions::builder();

            if let Some(extensions) = self.extensions {
                builder.extensions(extensions);
            }

            builder
                .build()
                .expect("configuration mismatch for `CheckExecutablePermissions`")
        }
    }

    register_checks! {
        CheckExecutablePermissionsConfig {
            "check_executable_permissions" => CommitCheckConfig,
            "check_executable_permissions/topic" => TopicCheckConfig,
        },
    }

    #[test]
    fn test_check_executable_permissions_config_empty() {
        let json = json!({});
        let check: CheckExecutablePermissionsConfig = serde_json::from_value(json).unwrap();

        assert_eq!(check.extensions, None);

        let check = check.into_check();

        itertools::assert_equal(&check.extensions, &[] as &[&str]);
    }

    #[test]
    fn test_check_executable_permissions_config_all_fields() {
        let exp_ext: String = "md".into();
        let json = json!({
            "extensions": [exp_ext],
        });
        let check: CheckExecutablePermissionsConfig = serde_json::from_value(json).unwrap();

        itertools::assert_equal(&check.extensions, &Some([exp_ext.clone()]));

        let check = check.into_check();

        itertools::assert_equal(&check.extensions, &[exp_ext]);
    }
}

#[cfg(test)]
mod tests {
    use git_checks_core::{Check, TopicCheck};

    use crate::test::*;
    use crate::CheckExecutablePermissions;

    const BAD_TOPIC: &str = "6ad8d4932466efc57ecccd3c80def3737b5d7e9a";
    const BINARY_TOPIC: &str = "f81d125d44faeb76d8d06de1394f35ab03d4ebf8";
    const DELETE_TOPIC: &str = "8e007a6e84b7b2ecc2f613a653997c436c6671f4";
    const DELETE_BINARY_TOPIC: &str = "02ba9984453024e1ca70fb1ab4c51ebd41801c47";
    const FIX_TOPIC: &str = "bea46a67f75380f1c17c25c7f89ffa9f47b27c06";
    const BINARY_FIX_TOPIC: &str = "3ddce524eb8aff0e6e0b7b6475d64347d0d6a57f";
    const LFS_TOPIC: &str = "58b4868402bf3f2e6160af345052c812f4cbe36f";
    const SYMLINK_COMMIT: &str = "00ffdf352196c16a453970de022a8b4343610ccf";

    #[test]
    fn test_check_executable_permissions_builder_default() {
        assert!(CheckExecutablePermissions::builder().build().is_ok());
    }

    #[test]
    fn test_check_executable_permissions_name_commit() {
        let check = CheckExecutablePermissions::default();
        assert_eq!(Check::name(&check), "check-executable-permissions");
    }

    #[test]
    fn test_check_executable_permissions_name_topic() {
        let check = CheckExecutablePermissions::default();
        assert_eq!(TopicCheck::name(&check), "check-executable-permissions");
    }

    fn check_executable_permissions_check(ext: &str) -> CheckExecutablePermissions {
        CheckExecutablePermissions::builder()
            .extensions([ext].iter().cloned())
            .build()
            .unwrap()
    }

    #[test]
    fn test_check_executable_permissions() {
        let check = check_executable_permissions_check(".exe");
        let result = run_check("test_check_executable_permissions", BAD_TOPIC, check);
        test_result_errors(
            result,
            &[
                "commit 6ad8d4932466efc57ecccd3c80def3737b5d7e9a adds `is-exec` with executable \
                 permissions, but the file does not look executable.",
                "commit 6ad8d4932466efc57ecccd3c80def3737b5d7e9a adds `not-exec-shebang` without \
                 executable permissions, but the file looks executable.",
                "commit 6ad8d4932466efc57ecccd3c80def3737b5d7e9a adds `not-exec.exe` without \
                 executable permissions, but the file looks executable.",
            ],
        );
    }

    #[test]
    fn test_check_executable_permissions_binary() {
        let check = check_executable_permissions_check(".exe");
        let result = run_check(
            "test_check_executable_permissions_binary",
            BINARY_TOPIC,
            check,
        );
        test_result_errors(result, &[
            "commit f5fd493ca51556d6cd0c42dfc8003925d77441f3 adds `elf-header` without executable \
             permissions, but the file looks executable.",
            "commit f5fd493ca51556d6cd0c42dfc8003925d77441f3 adds `macho-cigam-header` without \
             executable permissions, but the file looks executable.",
            "commit f5fd493ca51556d6cd0c42dfc8003925d77441f3 adds `macho-fat-cigam-header` \
             without executable permissions, but the file looks executable.",
            "commit f5fd493ca51556d6cd0c42dfc8003925d77441f3 adds `macho-fat-magic-header` \
             without executable permissions, but the file looks executable.",
            "commit f5fd493ca51556d6cd0c42dfc8003925d77441f3 adds `macho-magic-header` without \
             executable permissions, but the file looks executable.",
            "commit f3ea55a336feec4bc6c970695c5662fadea67054 adds `ar-header` with executable \
             permissions, but the file does not look executable.",
            "commit f81d125d44faeb76d8d06de1394f35ab03d4ebf8 adds `pe-le-header` without \
             executable permissions, but the file looks executable.",
        ]);
    }

    #[test]
    fn test_check_executable_permissions_delete_files() {
        let check = check_executable_permissions_check(".exe");
        let conf = make_check_conf(&check);

        let result = test_check_base(
            "test_check_executable_permissions_delete_files",
            DELETE_TOPIC,
            BAD_TOPIC,
            &conf,
        );
        test_result_ok(result);
    }

    #[test]
    fn test_check_executable_permissions_binary_delete_files() {
        let check = check_executable_permissions_check(".exe");
        let conf = make_check_conf(&check);

        let result = test_check_base(
            "test_check_executable_permissions_binary_delete_files",
            DELETE_BINARY_TOPIC,
            BINARY_TOPIC,
            &conf,
        );
        test_result_ok(result);
    }

    #[test]
    fn test_check_executable_permissions_topic() {
        let check = check_executable_permissions_check(".exe");
        let result = run_topic_check("test_check_executable_permissions_topic", BAD_TOPIC, check);
        test_result_errors(
            result,
            &[
                "adds `is-exec` with executable permissions, but the file does not look \
                 executable.",
                "adds `not-exec-shebang` without executable permissions, but the file looks \
                 executable.",
                "adds `not-exec.exe` without executable permissions, but the file looks \
                 executable.",
            ],
        );
    }

    #[test]
    fn test_check_executable_permissions_topic_delete_files() {
        let check = check_executable_permissions_check(".exe");
        run_topic_check_ok(
            "test_check_executable_permissions_topic_delete_files",
            DELETE_TOPIC,
            check,
        );
    }

    #[test]
    fn test_check_executable_permissions_topic_binary_delete_files() {
        let check = check_executable_permissions_check(".exe");
        run_topic_check_ok(
            "test_check_executable_permissions_topic_binary_delete_files",
            DELETE_BINARY_TOPIC,
            check,
        );
    }

    #[test]
    fn test_check_executable_permissions_topic_fixed() {
        let check = check_executable_permissions_check(".exe");
        run_topic_check_ok(
            "test_check_executable_permissions_topic_fixed",
            FIX_TOPIC,
            check,
        );
    }

    #[test]
    fn test_check_executable_permissions_topic_binary_fixed() {
        let check = check_executable_permissions_check(".exe");
        run_topic_check_ok(
            "test_check_executable_permissions_topic_binary_fixed",
            BINARY_FIX_TOPIC,
            check,
        );
    }

    #[test]
    fn test_check_executable_permissions_lfs() {
        let check = check_executable_permissions_check(".lfs");
        let conf = make_check_conf(&check);
        let result = test_check_base(
            "test_check_executable_permissions_lfs",
            LFS_TOPIC,
            BAD_TOPIC,
            &conf,
        );
        test_result_ok(result);
    }

    #[test]
    fn test_check_executable_permissions_ignore_symlinks() {
        let check = CheckExecutablePermissions::default();
        run_check_ok(
            "test_check_executable_permissions_ignore_symlinks",
            SYMLINK_COMMIT,
            check,
        );
    }

    #[test]
    fn test_check_executable_permissions_ignore_symlinks_topic() {
        let check = CheckExecutablePermissions::default();
        run_topic_check_ok(
            "test_check_executable_permissions_ignore_symlinks_topic",
            SYMLINK_COMMIT,
            check,
        );
    }
}