git-cmp

#!/usr/bin/env ruby
# Usage:
#
#   git cmp [BRANCH]
#
#   Opens a GitHub compare view, optionally against a specific [BRANCH]

require 'uri'

Config = Struct.new(
  :host, # github.com
  :repo, # zachmargolis/margs-dev
)

# https://github.com/zachmargolis/margs-dev.git
def parse_https_url(url)
  uri = URI.parse(url)
  Config.new(uri.host, clean_up_path(uri.path))
end

# git@github.com:zachmargolis/margs-dev.git
def parse_git_url(url)
  _git, rest = url.split('@', 2)
  host, path = rest.split(':', 2)
  Config.new(host, clean_up_path(path))
end

# "/zachmargolis/margs-dev.git" => "zachmargolis/margs-dev"
def clean_up_path(path)
  path.gsub(%r|^/|, '').chomp('.git')
end

def github_compare_url(config, branch_name, from_branch = nil)
  "https://#{config.host}/#{config.repo}/compare/" + (from_branch ? "#{from_branch}...#{branch_name}" : branch_name)
end

def gitlab_compare_url(config, branch_name, from_branch = nil)
  "https://#{config.host}/#{config.repo}/-/compare/#{from_branch || 'main'}...#{branch_name}"
end

origin_url = `git remote get-url origin`.chomp
branch_name = `git rev-parse --abbrev-ref HEAD`.chomp

config = begin
  parse_https_url(origin_url)
rescue URI::InvalidURIError
  parse_git_url(origin_url)
end

from_branch = ARGV.first
compare_url = if config.host.include?('github')
  github_compare_url(config, branch_name, from_branch)
else
  gitlab_compare_url(config, branch_name, from_branch)
end

system('open', compare_url)