use crate::bare::GitBare;
use crate::commit::create_commit::command_ok;
use crate::error::{GitError, GitResult};
use crate::pb::{RebaseRequest, RebaseResult, rebase_result};

const MAX_REBASE_COMMITS: usize = 10_000;
const MAX_REBASE_PATCH_BYTES: usize = 100 * 1024 * 1024;

impl GitBare {
    pub fn rebase(&self, request: RebaseRequest) -> GitResult<RebaseResult> {
        let branch = request.branch.clone();
        crate::sanitize::validate_ref_name(&branch)?;
        let upstream_revision = match request.upstream.and_then(|s| s.selector) {
            Some(crate::pb::object_selector::Selector::Oid(oid)) => {
                crate::sanitize::validate_oid_hex(&oid.hex)?;
                oid.hex
            }
            Some(crate::pb::object_selector::Selector::Revision(name)) => {
                crate::sanitize::validate_revision(&name.revision)?;
                name.revision
            }
            None => return Err(GitError::InvalidArgument("upstream is required".into())),
        };

        let repo = self.gix_repo()?;
        let branch_ref = format!("refs/heads/{}", branch);
        let branch_tip = repo
            .find_reference(branch_ref.as_str())
            .ok()
            .and_then(|mut r| r.peel_to_id().ok())
            .map(|id| id.to_string())
            .ok_or_else(|| GitError::RefNotFound(branch.clone()))?;

        let upstream_id = repo
            .rev_parse_single(upstream_revision.as_str())?
            .to_string();

        if branch_tip == upstream_id {
            return Ok(RebaseResult {
                status: rebase_result::Status::RebaseResultStatusAlreadyUpToDate as i32,
                head: None,
                conflicts: vec![],
            });
        }

        let result = duct::cmd(
            "git",
            [
                "--git-dir",
                self.bare_dir.to_string_lossy().as_ref(),
                "rev-list",
                "--reverse",
                &format!("{}..{}", upstream_id, branch_tip),
            ],
        )
        .stdout_capture()
        .stderr_capture()
        .unchecked()
        .run()?;
        if !result.status.success() {
            return Err(GitError::CommandFailed {
                status_code: result.status.code(),
                stderr: String::from_utf8_lossy(&result.stderr).into_owned(),
            });
        }

        let commits: Vec<String> = String::from_utf8_lossy(&result.stdout)
            .lines()
            .map(str::trim)
            .filter(|l| !l.is_empty())
            .map(String::from)
            .collect();

        if commits.len() > MAX_REBASE_COMMITS {
            return Err(GitError::InvalidArgument(format!(
                "too many commits to rebase ({} > max {MAX_REBASE_COMMITS})",
                commits.len()
            )));
        }

        if commits.is_empty() {
            return Ok(RebaseResult {
                status: rebase_result::Status::RebaseResultStatusAlreadyUpToDate as i32,
                head: None,
                conflicts: vec![],
            });
        }

        let mut current_tip = upstream_id.clone();
        for commit_hex in &commits {
            current_tip =
                self.rebase_one_commit(commit_hex, &current_tip, request.committer.as_ref())?;
        }

        self.update_branch_ref(&branch, &current_tip, Some(&branch_tip), false)?;

        Ok(RebaseResult {
            status: rebase_result::Status::RebaseResultStatusRebased as i32,
            head: Some(self.get_commit(crate::pb::GetCommitRequest {
                repository: request.repository,
                revision: Some(crate::pb::ObjectSelector {
                    selector: Some(crate::pb::object_selector::Selector::Revision(
                        crate::pb::ObjectName {
                            revision: current_tip,
                        },
                    )),
                }),
                include_stats: false,
                include_raw: false,
            })?),
            conflicts: vec![],
        })
    }

    fn rebase_one_commit(
        &self,
        commit_hex: &str,
        new_parent: &str,
        committer: Option<&crate::pb::Signature>,
    ) -> GitResult<String> {
        let repo = self.gix_repo()?;
        let id = repo.rev_parse_single(commit_hex)?;
        let obj = id
            .object()?
            .try_into_commit()
            .map_err(|e| GitError::Gix(e.to_string()))?;
        let message = obj.message_raw()?.to_string();
        let author = obj.author().ok();

        let bare = self.bare_dir.to_string_lossy().into_owned();
        let tmp_index = tempfile::Builder::new()
            .prefix("gitks-rebase-")
            .tempfile_in(&self.bare_dir)?;
        let idx_path = tmp_index.path().to_string_lossy().into_owned();

        let read_tree = duct::cmd("git", ["--git-dir", bare.as_str(), "read-tree", new_parent])
            .env("GIT_INDEX_FILE", &idx_path)
            .stdout_capture()
            .stderr_capture()
            .unchecked()
            .run()?;
        command_ok(read_tree)?;

        let diff = duct::cmd(
            "git",
            [
                "--git-dir",
                bare.as_str(),
                "format-patch",
                "--stdout",
                "--full-index",
                "--binary",
                "-1",
                commit_hex,
            ],
        )
        .env("GIT_INDEX_FILE", &idx_path)
        .stdout_capture()
        .stderr_capture()
        .unchecked()
        .run()?;
        let patch_data = command_ok(diff)?;
        if patch_data.len() > MAX_REBASE_PATCH_BYTES {
            return Err(GitError::InvalidArgument(format!(
                "rebase patch too large for {commit_hex} ({} bytes, max {MAX_REBASE_PATCH_BYTES})",
                patch_data.len()
            )));
        }

        let apply = duct::cmd(
            "git",
            [
                "--git-dir",
                bare.as_str(),
                "apply",
                "--cached",
                "--allow-empty",
                "-",
            ],
        )
        .env("GIT_INDEX_FILE", &idx_path)
        .stdin_bytes(patch_data.as_bytes())
        .stdout_capture()
        .stderr_capture()
        .unchecked()
        .run()?;
        if !apply.status.success() {
            return Err(GitError::Internal(format!(
                "rebase apply failed for {}: {}",
                commit_hex,
                String::from_utf8_lossy(&apply.stderr)
            )));
        }

        let write_tree = duct::cmd("git", ["--git-dir", bare.as_str(), "write-tree"])
            .env("GIT_INDEX_FILE", &idx_path)
            .stdout_capture()
            .stderr_capture()
            .unchecked()
            .run()?;
        let tree_id = command_ok(write_tree)?.trim().to_string();

        let parents = vec![new_parent.to_string()];
        self.commit_tree(
            &tree_id,
            &parents,
            &message,
            author
                .as_ref()
                .map(|a| crate::commit::get_commit::gix_sig_to_pb(a))
                .as_ref(),
            committer,
        )
    }
}