use crate::{
    parser::{GitReceivePackArgs, GitUploadPackArgs},
    ShackleError,
};
use git2::{Repository, RepositoryInitMode, RepositoryInitOptions};
use std::{
    path::{Path, PathBuf},
    process::Command,
};
use user_info::{get_user_groups, get_username};

pub struct GitInitResult {
    pub path: PathBuf,
}

fn personal_git_dir() -> Result<PathBuf, ShackleError> {
    let username = get_username().ok_or(ShackleError::UserReadError)?;
    Ok(Path::new("git").join(username))
}

fn group_git_dir(group: &str) -> Result<PathBuf, ShackleError> {
    let groups = get_user_groups();
    if !groups.iter().any(|g| g == group) {
        Err(ShackleError::InvalidGroup)
    } else {
        Ok(Path::new("git").join(group))
    }
}

fn is_valid_personal_git_repo(path: &PathBuf) -> Result<bool, ShackleError> {
    let valid_dir = personal_git_dir()?;
    let relative_path = match path.strip_prefix(&valid_dir) {
        Ok(relative_path) => relative_path,
        Err(_) => {
            return Ok(false);
        }
    };

    if relative_path.parent() != Some(Path::new(""))
        || relative_path.extension().map(|ext| ext == "git") != Some(true)
    {
        return Ok(false);
    }

    Ok(true)
}

pub fn init(repo_name: &str, group: &Option<String>) -> Result<GitInitResult, ShackleError> {
    fn init_group(repo_name: &str, group: &str) -> Result<GitInitResult, ShackleError> {
        let path = group_git_dir(group)?.join(repo_name).with_extension("git");

        Repository::init_opts(
            &path,
            &RepositoryInitOptions::new()
                .bare(true)
                .mode(RepositoryInitMode::SHARED_GROUP)
                .mkdir(true)
                .no_reinit(true),
        )?;
        Ok(GitInitResult { path })
    }

    fn init_personal(repo_name: &str) -> Result<GitInitResult, ShackleError> {
        let path = personal_git_dir()?.join(repo_name).with_extension("git");

        Repository::init_opts(
            &path,
            &RepositoryInitOptions::new()
                .bare(true)
                .mkdir(true)
                .no_reinit(true),
        )?;
        Ok(GitInitResult { path })
    }

    match group {
        Some(group) => init_group(repo_name, group),
        None => init_personal(repo_name),
    }
}

pub fn upload_pack(upload_pack_args: &GitUploadPackArgs) -> Result<(), ShackleError> {
    if !is_valid_personal_git_repo(&upload_pack_args.directory)? {
        return Err(ShackleError::InvalidDirectory);
    }

    let mut command = Command::new("git-upload-pack");
    if upload_pack_args.strict {
        command.arg("strict");
    }
    if upload_pack_args.no_strict {
        command.arg("no-strict");
    }
    if let Some(timeout) = upload_pack_args.timeout {
        command.args(["timeout", &timeout.to_string()]);
    }
    if upload_pack_args.stateless_rpc {
        command.arg("stateless-rpc");
    }
    if upload_pack_args.advertise_refs {
        command.arg("advertise-refs");
    }
    command.arg(&upload_pack_args.directory);

    command.spawn()?.wait()?;
    Ok(())
}

pub fn receive_pack(receive_pack_args: &GitReceivePackArgs) -> Result<(), ShackleError> {
    if !is_valid_personal_git_repo(&receive_pack_args.directory)? {
        return Err(ShackleError::InvalidDirectory);
    }

    let mut command = Command::new("git-receive-pack");
    if receive_pack_args.http_backend_info_refs {
        command.arg("--http-backend-info-refs");
    }
    command.arg(&receive_pack_args.directory);

    command.spawn()?.wait()?;
    Ok(())
}