// 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 std::path::PathBuf;

use crates::git_checks_core::impl_prelude::*;
use crates::thiserror::Error;

#[derive(Debug, Error)]
enum SubmoduleAvailableError {
    #[error("failed to get the merge-base for {} against the tracking branch {} in {}: {}", commit, branch, submodule.display(), output)]
    MergeBase {
        submodule: PathBuf,
        commit: CommitId,
        branch: String,
        output: String,
    },
    #[error("failed to list refs from {} to {} in {}: {}", branch, commit, submodule.display(), output)]
    RevList {
        submodule: PathBuf,
        commit: CommitId,
        branch: String,
        output: String,
    },
}

impl SubmoduleAvailableError {
    fn merge_base(submodule: &FileName, commit: CommitId, branch: String, output: &[u8]) -> Self {
        SubmoduleAvailableError::MergeBase {
            submodule: submodule.as_path().into(),
            commit,
            branch,
            output: String::from_utf8_lossy(output).into(),
        }
    }

    fn rev_list(submodule: &FileName, commit: CommitId, branch: String, output: &[u8]) -> Self {
        SubmoduleAvailableError::RevList {
            submodule: submodule.as_path().into(),
            commit,
            branch,
            output: String::from_utf8_lossy(output).into(),
        }
    }
}

/// Check that submodules are reachable from a given branch and available.
#[derive(Builder, Debug, Clone, Copy)]
#[builder(field(private))]
pub struct SubmoduleAvailable {
    /// Whether the first-parent history is required to contain commits or not.
    ///
    /// If the merge commit of the submodule into the tracked branch should be required, set this
    /// flag.
    ///
    /// Configuration: Optional
    /// Default: `false`
    #[builder(default = "false")]
    require_first_parent: bool,
}

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

impl Default for SubmoduleAvailable {
    fn default() -> Self {
        SubmoduleAvailable {
            require_first_parent: false,
        }
    }
}

impl Check for SubmoduleAvailable {
    fn name(&self) -> &str {
        "submodule-available"
    }

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

        for diff in &commit.diffs {
            // Ignore diffs which are not submodules on the new side.
            if diff.new_mode != "160000" {
                continue;
            }

            // Ignore deleted submodules.
            if let StatusChange::Deleted = diff.status {
                continue;
            }

            let submodule_ctx = if let Some(ctx) = SubmoduleContext::new(ctx, diff.name.as_ref()) {
                ctx
            } else {
                result.add_alert(
                    format!("submodule at `{}` is not configured.", diff.name),
                    false,
                );

                continue;
            };

            let submodule_commit = &diff.new_blob;

            let cat_file = submodule_ctx
                .context
                .git()
                .arg("cat-file")
                .arg("-t")
                .arg(submodule_commit.as_str())
                .output()
                .map_err(|err| GitError::subcommand("cat-file -t", err))?;
            let object_type = String::from_utf8_lossy(&cat_file.stdout);
            if !cat_file.status.success() || object_type.trim() != "commit" {
                result
                    .add_error(format!(
                        "commit {} references an unreachable commit {} at `{}`; please make the \
                         commit available in the {} repository on the `{}` branch first.",
                        commit.sha1,
                        submodule_commit,
                        submodule_ctx.path,
                        submodule_ctx.url,
                        submodule_ctx.branch,
                    ))
                    .make_temporary();
                continue;
            }

            let merge_base = submodule_ctx
                .context
                .git()
                .arg("merge-base")
                .arg(submodule_commit.as_str())
                .arg(submodule_ctx.branch)
                .output()
                .map_err(|err| GitError::subcommand("merge-base", err))?;
            if !merge_base.status.success() {
                return Err(SubmoduleAvailableError::merge_base(
                    &diff.name,
                    submodule_commit.clone(),
                    submodule_ctx.branch.into(),
                    &merge_base.stderr,
                )
                .into());
            }
            let base = String::from_utf8_lossy(&merge_base.stdout);

            if base.trim() != submodule_commit.as_str() {
                result
                    .add_error(format!(
                        "commit {} references the commit {} at `{}`, but it is not available on \
                         the tracked branch `{}`; please make the commit available from the `{}` \
                         branch first.",
                        commit.sha1,
                        submodule_commit,
                        submodule_ctx.path,
                        submodule_ctx.branch,
                        submodule_ctx.branch,
                    ))
                    .make_temporary();
                continue;
            }

            if self.require_first_parent {
                let refs = submodule_ctx
                    .context
                    .git()
                    .arg("rev-list")
                    .arg("--first-parent") // only look at first-parent history
                    .arg("--reverse") // start with oldest commits
                    .arg(submodule_ctx.branch)
                    .arg(format!("^{}~", submodule_commit))
                    .output()
                    .map_err(|err| GitError::subcommand("rev-list", err))?;
                if !refs.status.success() {
                    return Err(SubmoduleAvailableError::rev_list(
                        &diff.name,
                        submodule_commit.clone(),
                        submodule_ctx.branch.into(),
                        &refs.stderr,
                    )
                    .into());
                }
                let refs = String::from_utf8_lossy(&refs.stdout);

                if !refs.lines().any(|rev| rev == submodule_commit.as_str()) {
                    // This is not temporary because we've already determined above that it is in
                    // the history of the target branch in the first place; it not being in the
                    // first-parent isn't going to change.
                    result.add_error(format!(
                        "commit {} references the commit {} at `{}`, but it is not available as a \
                         first-parent of the tracked branch `{}`; please choose the commit where \
                         it was merged into the `{}` branch.",
                        commit.sha1,
                        submodule_commit,
                        submodule_ctx.path,
                        submodule_ctx.branch,
                        submodule_ctx.branch,
                    ));
                    continue;
                }
            }
        }

        Ok(result)
    }
}

#[cfg(feature = "config")]
pub(crate) mod config {
    use crates::git_checks_config::{CommitCheckConfig, IntoCheck};
    use crates::inventory;
    #[cfg(test)]
    use crates::serde_json;

    use SubmoduleAvailable;

    /// Configuration for the `SubmoduleAvailable` check.
    ///
    /// The `require_first_parent` key is a boolean which defaults to `false`.
    ///
    /// This check is registered as a commit check with the name `"submodule_available"`.
    ///
    /// # Example
    ///
    /// ```json
    /// {
    ///     "require_first_parent": false
    /// }
    /// ```
    #[derive(Deserialize, Debug)]
    pub struct SubmoduleAvailableConfig {
        #[serde(default)]
        require_first_parent: Option<bool>,
    }

    impl IntoCheck for SubmoduleAvailableConfig {
        type Check = SubmoduleAvailable;

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

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

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

    register_checks! {
        SubmoduleAvailableConfig {
            "submodule_available" => CommitCheckConfig,
        },
    }

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

        assert_eq!(check.require_first_parent, None);
    }

    #[test]
    fn test_submodule_available_config_all_fields() {
        let json = json!({
            "require_first_parent": true,
        });
        let check: SubmoduleAvailableConfig = serde_json::from_value(json).unwrap();

        assert_eq!(check.require_first_parent, Some(true));
    }
}

#[cfg(test)]
mod tests {
    use test::*;
    use SubmoduleAvailable;

    const BASE_COMMIT: &str = "fe90ee22ae3ce4b4dc41f8d0876e59355ff1e21c";
    const MOVE_TOPIC: &str = "2088079e35503be3be41dbdca55080ced95614e1";
    const MOVE_NOT_FIRST_PARENT_TOPIC: &str = "eb4df16a8a38f6ca30b6e67cfbca0672156b54d2";
    const UNAVAILABLE_TOPIC: &str = "1b9275caca1557611df19d1dfea687c3ef302eef";
    const NOT_ANCESTOR_TOPIC: &str = "07fb2ca9c1c8c0ddfcf921e762688ffcd476bc09";

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

    #[test]
    fn test_submodule_unconfigured() {
        let check = SubmoduleAvailable::default();
        let result = run_check("test_submodule_unconfigured", BASE_COMMIT, check);

        assert_eq!(result.warnings().len(), 0);
        assert_eq!(result.alerts().len(), 1);
        assert_eq!(
            result.alerts()[0],
            "submodule at `submodule` is not configured.",
        );
        assert_eq!(result.errors().len(), 0);
        assert_eq!(result.temporary(), false);
        assert_eq!(result.allowed(), false);
        assert_eq!(result.pass(), true);
    }

    #[test]
    fn test_submodule_move() {
        let check = SubmoduleAvailable::default();
        let conf = make_check_conf(&check);

        let result = test_check_submodule("test_submodule_move", MOVE_TOPIC, &conf);
        test_result_ok(result);
    }

    #[test]
    fn test_submodule_move_not_first_parent() {
        let check = SubmoduleAvailable::default();
        let conf = make_check_conf(&check);

        let result = test_check_submodule(
            "test_submodule_move_not_first_parent",
            MOVE_NOT_FIRST_PARENT_TOPIC,
            &conf,
        );
        test_result_ok(result);
    }

    #[test]
    fn test_submodule_move_not_first_parent_reject() {
        let check = SubmoduleAvailable::builder()
            .require_first_parent(true)
            .build()
            .unwrap();
        let conf = make_check_conf(&check);

        let result = test_check_submodule(
            "test_submodule_move_not_first_parent_reject",
            MOVE_NOT_FIRST_PARENT_TOPIC,
            &conf,
        );
        test_result_errors(result, &[
            "commit eb4df16a8a38f6ca30b6e67cfbca0672156b54d2 references the commit \
             c2bd427807b40b1715b8d1441fe92f50e8ad1769 at `submodule`, but it is not available as a \
             first-parent of the tracked branch `master`; please choose the commit where it was \
             merged into the `master` branch.",
        ]);
    }

    #[test]
    fn test_submodule_unavailable() {
        let check = SubmoduleAvailable::default();
        let conf = make_check_conf(&check);

        let result = test_check_submodule("test_submodule_unavailable", UNAVAILABLE_TOPIC, &conf);

        assert_eq!(result.warnings().len(), 0);
        assert_eq!(result.alerts().len(), 0);
        assert_eq!(result.errors().len(), 1);
        assert_eq!(
            result.errors()[0],
            "commit 1b9275caca1557611df19d1dfea687c3ef302eef references an unreachable commit \
             4b029c2e0f186d681caa071fa4dd7eb1f0f033f6 at `submodule`; please make the commit \
             available in the https://gitlab.kitware.com/utils/test-repo.git repository on the \
             `master` branch first.",
        );
        assert_eq!(result.temporary(), true);
        assert_eq!(result.allowed(), false);
        assert_eq!(result.pass(), false);
    }

    #[test]
    fn test_submodule_not_ancestor() {
        let check = SubmoduleAvailable::default();
        let conf = make_check_conf(&check);

        let result = test_check_submodule("test_submodule_not_ancestor", NOT_ANCESTOR_TOPIC, &conf);

        assert_eq!(result.warnings().len(), 0);
        assert_eq!(result.alerts().len(), 0);
        assert_eq!(result.errors().len(), 1);
        assert_eq!(
            result.errors()[0],
            "commit 07fb2ca9c1c8c0ddfcf921e762688ffcd476bc09 references the commit \
             bd89a556b6ab6f378a776713439abbc1c1f15b6d at `submodule`, but it is not available on \
             the tracked branch `master`; please make the commit available from the `master` \
             branch first."
        );
        assert_eq!(result.temporary(), true);
        assert_eq!(result.allowed(), false);
        assert_eq!(result.pass(), false);
    }
}