//! Copyright (c) 2022-2026 GitDataAi All rights reserved.

use crate::bare::GitBare;
use crate::error::{GitError, GitResult};
use crate::oid::ZERO_OID;
use crate::pb::{
    CreateCommitRequest, CreateCommitResponse, GetCommitRequest, ObjectName, ObjectSelector,
    create_commit_action, object_selector,
};

impl GitBare {
    pub fn create_commit(&self, request: CreateCommitRequest) -> GitResult<CreateCommitResponse> {
        crate::sanitize::validate_ref_name(&request.branch)?;
        if let Some(rev) = request.start_revision.as_ref() {
            match rev.selector.as_ref() {
                Some(object_selector::Selector::Revision(name)) => {
                    crate::sanitize::validate_revision(&name.revision)?;
                }
                Some(object_selector::Selector::Oid(oid)) => {
                    crate::sanitize::validate_oid_hex(&oid.hex)?;
                }
                None => {} // will use branch name, already validated
            }
        }

        if request.actions.len() > crate::config::MAX_ACTIONS_PER_COMMIT {
            return Err(GitError::InvalidArgument(format!(
                "too many commit actions ({} > max {})",
                request.actions.len(),
                crate::config::MAX_ACTIONS_PER_COMMIT,
            )));
        }

        let repo = self.gix_repo()?;
        let branch = request.branch.clone();
        tracing::debug!(
            repo = %self.bare_dir.display(),
            branch = %branch,
            actions = request.actions.len(),
            "creating commit"
        );
        let start_rev = match request.start_revision.clone().and_then(|s| s.selector) {
            Some(object_selector::Selector::Oid(oid)) => {
                crate::sanitize::validate_oid_hex(&oid.hex)?;
                oid.hex
            }
            Some(object_selector::Selector::Revision(name)) => name.revision,
            None => request.branch.clone(),
        };
        let parent_id = match repo.rev_parse_single(start_rev.as_str()) {
            Ok(id) => Some(id.to_string()),
            Err(_) => None, // branch/revision does not exist yet — will create initial commit
        };
        let current_branch_tip =
            match repo.find_reference(format!("refs/heads/{}", request.branch).as_str()) {
                Ok(mut r) => r.peel_to_id().ok().map(|id| id.to_string()),
                Err(_) => None, // branch does not exist yet
            };

        let tree_id = if request.actions.is_empty() {
            let Some(parent) = parent_id.as_ref() else {
                return Err(GitError::InvalidArgument(
                    "cannot create an empty root commit without file actions".into(),
                ));
            };
            self.rev_parse_tree(parent)?
        } else {
            self.tree_from_actions(parent_id.as_deref(), &request.actions)?
        };

        let message = commit_message_with_trailers(&request);
        let parents: Vec<String> = parent_id.iter().cloned().collect();
        let commit_id = self.commit_tree(
            &tree_id,
            &parents,
            &message,
            request.author.as_ref(),
            request.committer.as_ref(),
        )?;
        self.update_branch_after_commit(&request, &commit_id, current_branch_tip.as_deref())?;

        let revision = Some(ObjectSelector {
            selector: Some(object_selector::Selector::Revision(ObjectName {
                revision: commit_id,
            })),
        });
        Ok(CreateCommitResponse {
            commit: Some(self.get_commit(GetCommitRequest {
                repository: request.repository,
                revision,
                include_stats: false,
                include_raw: false,
            })?),
            branch: request.branch,
        })
    }

    fn rev_parse_tree(&self, revision: &str) -> GitResult<String> {
        let result = duct::cmd(
            "git",
            [
                "--git-dir",
                self.bare_dir.to_string_lossy().as_ref(),
                "rev-parse",
                &format!("{revision}^{{tree}}"),
            ],
        )
        .stdout_capture()
        .stderr_capture()
        .unchecked()
        .run()?;
        command_ok(result).map(|stdout| stdout.trim().to_string())
    }

    fn tree_from_actions(
        &self,
        parent_id: Option<&str>,
        actions: &[crate::pb::CreateCommitAction],
    ) -> GitResult<String> {
        // Use system temp directory instead of bare_dir to avoid clutter
        // and ensure proper cleanup even if process crashes
        let tmp_index = tempfile::Builder::new()
            .prefix("gitks-index-")
            .tempfile()
            .map_err(GitError::Io)?;
        let tmp_index_path = tmp_index.path().to_string_lossy().into_owned();

        if let Some(parent) = parent_id {
            let read_tree = duct::cmd(
                "git",
                [
                    "--git-dir",
                    self.bare_dir.to_string_lossy().as_ref(),
                    "read-tree",
                    parent,
                ],
            )
            .env("GIT_INDEX_FILE", &tmp_index_path)
            .stdout_capture()
            .stderr_capture()
            .unchecked()
            .run()?;
            command_ok(read_tree)?;
        }

        for action in actions {
            self.apply_commit_action(&tmp_index_path, action)?;
        }

        let write_tree = duct::cmd(
            "git",
            [
                "--git-dir",
                self.bare_dir.to_string_lossy().as_ref(),
                "write-tree",
            ],
        )
        .env("GIT_INDEX_FILE", &tmp_index_path)
        .stdout_capture()
        .stderr_capture()
        .unchecked()
        .run()?;
        command_ok(write_tree).map(|stdout| stdout.trim().to_string())
    }

    fn apply_commit_action(
        &self,
        index_path: &str,
        action: &crate::pb::CreateCommitAction,
    ) -> GitResult<()> {
        if action.content.len() > crate::config::MAX_ACTION_CONTENT_BYTES {
            return Err(GitError::InvalidArgument(format!(
                "action content too large ({} bytes, max {})",
                action.content.len(),
                crate::config::MAX_ACTION_CONTENT_BYTES,
            )));
        }

        if !action.file_path.is_empty() {
            crate::sanitize::validate_file_path(&action.file_path)?;
        }
        if !action.previous_path.is_empty() {
            crate::sanitize::validate_file_path(&action.previous_path)?;
        }

        let action_type = create_commit_action::Action::try_from(action.action)
            .unwrap_or(create_commit_action::Action::CreateCommitActionUnspecified);
        match action_type {
            create_commit_action::Action::CreateCommitActionCreate
            | create_commit_action::Action::CreateCommitActionUpdate => {
                let hash = duct::cmd(
                    "git",
                    [
                        "--git-dir",
                        self.bare_dir.to_string_lossy().as_ref(),
                        "hash-object",
                        "-w",
                        "--stdin",
                    ],
                )
                .stdin_bytes(action.content.clone())
                .stdout_capture()
                .stderr_capture()
                .unchecked()
                .run()?;
                let blob = command_ok(hash)?.trim().to_string();
                let mode = if action.executable {
                    "100755"
                } else {
                    "100644"
                };
                self.update_index_cacheinfo(index_path, mode, &blob, &action.file_path)
            }
            create_commit_action::Action::CreateCommitActionDelete => {
                let result = duct::cmd(
                    "git",
                    [
                        "--git-dir",
                        self.bare_dir.to_string_lossy().as_ref(),
                        "update-index",
                        "--force-remove",
                        &action.file_path,
                    ],
                )
                .env("GIT_INDEX_FILE", index_path)
                .env("GIT_WORK_TREE", self.bare_dir.to_string_lossy().as_ref())
                .stdout_capture()
                .stderr_capture()
                .unchecked()
                .run()?;
                command_ok(result).map(|_| ())
            }
            create_commit_action::Action::CreateCommitActionMove => {
                if action.previous_path.is_empty() {
                    return Err(GitError::InvalidArgument(
                        "MOVE action requires previous_path".into(),
                    ));
                }
                let (mode, oid) = self.index_entry(index_path, &action.previous_path)?;
                self.update_index_cacheinfo(index_path, &mode, &oid, &action.file_path)?;
                let remove = duct::cmd(
                    "git",
                    [
                        "--git-dir",
                        self.bare_dir.to_string_lossy().as_ref(),
                        "update-index",
                        "--force-remove",
                        &action.previous_path,
                    ],
                )
                .env("GIT_INDEX_FILE", index_path)
                .env("GIT_WORK_TREE", self.bare_dir.to_string_lossy().as_ref())
                .stdout_capture()
                .stderr_capture()
                .unchecked()
                .run()?;
                command_ok(remove).map(|_| ())
            }
            create_commit_action::Action::CreateCommitActionChmod => {
                let (_old_mode, oid) = self.index_entry(index_path, &action.file_path)?;
                let mode = if action.executable {
                    "100755"
                } else {
                    "100644"
                };
                self.update_index_cacheinfo(index_path, mode, &oid, &action.file_path)
            }
            create_commit_action::Action::CreateCommitActionUnspecified => Err(
                GitError::InvalidArgument("unspecified commit action".into()),
            ),
        }
    }

    fn index_entry(&self, index_path: &str, path: &str) -> GitResult<(String, String)> {
        let result = duct::cmd(
            "git",
            [
                "--git-dir",
                self.bare_dir.to_string_lossy().as_ref(),
                "ls-files",
                "-s",
                "--",
                path,
            ],
        )
        .env("GIT_INDEX_FILE", index_path)
        .env("GIT_WORK_TREE", self.bare_dir.to_string_lossy().as_ref())
        .stdout_capture()
        .stderr_capture()
        .unchecked()
        .run()?;
        let stdout = command_ok(result)?;
        let line = stdout
            .lines()
            .next()
            .ok_or_else(|| GitError::NotFound(path.to_string()))?;
        let parts = line.split_whitespace().collect::<Vec<_>>();
        if parts.len() < 2 {
            return Err(GitError::ParseError(format!(
                "invalid index entry for {path}: {line}"
            )));
        }
        Ok((parts[0].to_string(), parts[1].to_string()))
    }

    fn update_index_cacheinfo(
        &self,
        index_path: &str,
        mode: &str,
        oid: &str,
        path: &str,
    ) -> GitResult<()> {
        let result = duct::cmd(
            "git",
            [
                "--git-dir",
                self.bare_dir.to_string_lossy().as_ref(),
                "update-index",
                "--add",
                "--cacheinfo",
                mode,
                oid,
                path,
            ],
        )
        .env("GIT_INDEX_FILE", index_path)
        .env("GIT_WORK_TREE", self.bare_dir.to_string_lossy().as_ref())
        .stdout_capture()
        .stderr_capture()
        .unchecked()
        .run()?;
        command_ok(result).map(|_| ())
    }

    pub(crate) fn commit_tree(
        &self,
        tree_id: &str,
        parent_ids: &[String],
        message: &str,
        author: Option<&crate::pb::Signature>,
        committer: Option<&crate::pb::Signature>,
    ) -> GitResult<String> {
        if message.len() > crate::config::MAX_COMMIT_MESSAGE_BYTES {
            return Err(GitError::InvalidArgument(format!(
                "commit message too large ({} bytes, max {})",
                message.len(),
                crate::config::MAX_COMMIT_MESSAGE_BYTES,
            )));
        }

        let mut args = vec![
            "--git-dir".to_string(),
            self.bare_dir.to_string_lossy().into_owned(),
            "commit-tree".into(),
            tree_id.to_string(),
        ];
        for parent in parent_ids {
            args.push("-p".into());
            args.push(parent.clone());
        }
        args.push("-m".into());
        args.push(message.to_string());

        let mut cmd = duct::cmd("git", &args).stdout_capture().stderr_capture();
        if let Some(author) = author.and_then(|s| s.identity.as_ref()) {
            cmd = cmd
                .env("GIT_AUTHOR_NAME", &author.name)
                .env("GIT_AUTHOR_EMAIL", &author.email);
        }
        if let Some(committer) = committer.and_then(|s| s.identity.as_ref()) {
            cmd = cmd
                .env("GIT_COMMITTER_NAME", &committer.name)
                .env("GIT_COMMITTER_EMAIL", &committer.email);
        }

        let commit = cmd.unchecked().run()?;
        command_ok(commit).map(|stdout| stdout.trim().to_string())
    }

    fn update_branch_after_commit(
        &self,
        request: &CreateCommitRequest,
        commit_id: &str,
        current_branch_tip: Option<&str>,
    ) -> GitResult<()> {
        let refname = format!("refs/heads/{}", request.branch);
        let mut args = vec![
            "--git-dir".to_string(),
            self.bare_dir.to_string_lossy().into_owned(),
            "update-ref".into(),
            refname,
            commit_id.to_string(),
        ];
        if !request.force {
            args.push(current_branch_tip.unwrap_or(ZERO_OID).to_string());
        }

        let update = duct::cmd("git", &args)
            .stdout_capture()
            .stderr_capture()
            .unchecked()
            .run()?;
        command_ok(update).map(|_| ())
    }
}

fn commit_message_with_trailers(request: &CreateCommitRequest) -> String {
    if request.trailers.is_empty() {
        return request.message.clone();
    }

    let mut message = request.message.trim_end().to_string();
    message.push_str("\n\n");
    for trailer in &request.trailers {
        let separator = if trailer.separator_present { ": " } else { " " };
        message.push_str(&trailer.key);
        message.push_str(separator);
        message.push_str(&trailer.value);
        message.push('\n');
    }
    message
}

pub(crate) fn command_ok(output: std::process::Output) -> GitResult<String> {
    if output.status.success() {
        Ok(String::from_utf8_lossy(&output.stdout).into_owned())
    } else {
        Err(GitError::CommandFailed {
            status_code: output.status.code(),
            stderr: String::from_utf8_lossy(&output.stderr).into_owned(),
        })
    }
}