module git

import strings
import net.http
import os

pub fn parse_branch_name_from_receive_upload(upload string) ?string {
    upload_lines := upload.split_into_lines()
    if upload_lines.len == 0 {
        return none
    }
    upload_header := upload_lines[0]
    header_parts := upload_header.fields()
    if header_parts.len < 3 {
        return none
    }
    branch_reference := header_parts[2]
    branch_name_raw := get_branch_name_from_reference(branch_reference)
    branch_name := branch_name_raw.trim_space().trim('\0')
    if branch_name.len == 0 {
        return none
    }
    return branch_name
}

// parse_git_branch_with_last_hash parses output from `git branch -a`
// returns the branch name
pub fn parse_git_branch_output(output string) string {
    output_parts := output.fields()
    asterisk_or_branch_name := output_parts[0]
    if asterisk_or_branch_name == '*' {
        return output_parts[1]
    }
    return output_parts[0]
}

pub fn flush_packet() string {
    return '0000'
}

pub fn write_packet(value string) string {
    packet_length := (value.len + 4).hex()
    return strings.repeat(`0`, 4 - packet_length.len) + packet_length + value
}

pub fn check_git_repo_url(url string) bool {
    repo_url := remove_git_extension_if_exists(url)
    refs_url := '${repo_url}/info/refs?service=git-upload-pack'
    mut headers := http.new_header()
    headers.add_custom('User-Agent', 'git/2.30.0') or {}
    headers.add_custom('Git-Protocol', 'version=2') or {}
    config := http.FetchConfig{
        url:    refs_url
        header: headers
    }
    println('URL=$refs_url $config')
    response := http.fetch(config) or { return false }
    println('response=$response')
    if response.status_code != 200 {
        return false
    }
    return response.body.contains('service=git-upload-pack')
}

pub fn get_git_executable_path() ?string {
    return os.find_abs_path_of_executable('git') or { none }
}

pub fn remove_git_extension_if_exists(git_repository_name string) string {
    return git_repository_name.trim_string_right('.git')
}

fn get_branch_name_from_reference(value string) string {
    return value.after('refs/heads/')
}