use crate::bare::GitBare;
use crate::error::GitResult;
use crate::pb::{CheckMergeRequest, MergeResult, merge_result};

impl GitBare {
    pub fn check_merge(&self, request: CheckMergeRequest) -> GitResult<MergeResult> {
        let target = match request.target.and_then(|s| s.selector) {
            Some(crate::pb::object_selector::Selector::Oid(oid)) => oid.hex,
            Some(crate::pb::object_selector::Selector::Revision(name)) => name.revision,
            None => "HEAD".into(),
        };
        let source = match request.source.and_then(|s| s.selector) {
            Some(crate::pb::object_selector::Selector::Oid(oid)) => oid.hex,
            Some(crate::pb::object_selector::Selector::Revision(name)) => name.revision,
            None => "HEAD".into(),
        };

        let repo = self.gix_repo()?;
        let target_id = repo.rev_parse_single(target.as_str())?;
        let source_id = repo.rev_parse_single(source.as_str())?;

        if target_id == source_id {
            return Ok(MergeResult {
                status: merge_result::Status::MergeResultStatusAlreadyUpToDate as i32,
                commit: None,
                merge_base: Some(self.oid_to_pb(target_id.to_string())),
                conflicts: vec![],
                stats: None,
                message: String::from("Already up to date"),
            });
        }

        let merge_base = repo
            .merge_base(target_id.detach(), source_id.detach())
            .ok()
            .map(|id| id.to_string());

        if let Some(ref base) = merge_base {
            if *base == target_id.to_string() {
                return Ok(MergeResult {
                    status: merge_result::Status::MergeResultStatusFastForward as i32,
                    commit: None,
                    merge_base: Some(self.oid_to_pb(base.clone())),
                    conflicts: vec![],
                    stats: None,
                    message: String::from("Fast-forward"),
                });
            }
            if *base == source_id.to_string() {
                return Ok(MergeResult {
                    status: merge_result::Status::MergeResultStatusAlreadyUpToDate as i32,
                    commit: None,
                    merge_base: Some(self.oid_to_pb(base.clone())),
                    conflicts: vec![],
                    stats: None,
                    message: String::from("Already up to date"),
                });
            }
        }

        let merge_base_oid = merge_base.as_ref().map(|b| self.oid_to_pb(b.clone()));

        let result = duct::cmd(
            "git",
            [
                "--git-dir",
                self.bare_dir.to_string_lossy().as_ref(),
                "merge-tree",
                "--write-tree",
                "--no-messages",
                "-z",
                &target,
                &source,
            ],
        )
        .stdout_capture()
        .stderr_capture()
        .unchecked()
        .run()?;

        let stdout = String::from_utf8_lossy(&result.stdout).into_owned();

        if result.status.success() {
            Ok(MergeResult {
                status: merge_result::Status::MergeResultStatusMerged as i32,
                commit: None,
                merge_base: merge_base_oid,
                conflicts: vec![],
                stats: None,
                message: stdout.trim().to_string(),
            })
        } else {
            let conflicts = stdout
                .split('\0')
                .filter(|s| !s.is_empty())
                .map(|path| crate::pb::MergeConflict {
                    path: path.to_string(),
                    ..Default::default()
                })
                .collect();
            Ok(MergeResult {
                status: merge_result::Status::MergeResultStatusConflicts as i32,
                commit: None,
                merge_base: merge_base_oid,
                conflicts,
                stats: None,
                message: String::from("Merge conflicts detected"),
            })
        }
    }
}