module Ninny
  class Git
    extend Forwardable
    NO_BRANCH = "(no branch)"
    DEFAULT_DIRTY_MESSAGE = "Your Git index is not clean. Commit, stash, or otherwise clean up the index before continuing."
    DIRTY_CONFIRM_MESSAGE = "Your Git index is not clean. Do you want to continue?"

    # branch prefixes
    DEPLOYABLE_PREFIX = "deployable"
    STAGING_PREFIX = "staging"
    QAREADY_PREFIX = "qaready"

    def_delegators :git, :branch

    attr_reader :git

    def initialize
      @git = ::Git.open(Dir.pwd)
    end

    def command(*args)
      git.lib.send(:command, *args)
    end

    def current_branch
      git.branch(current_branch_name)
    end

    def current_branch_name
      name = git.current_branch
      if name == NO_BRANCH
        raise NotOnBranch, "Not currently checked out to a particular branch"
      else
        name
      end
    end

    def merge(branch_name)
      if_clean do
        git.fetch
        current_branch.merge("origin/#{branch_name}")
        raise MergeFailed unless clean?
        push
      end
    end

    # Public: Push the current branch to GitHub
    def push
      if_clean do
        git.push('origin', current_branch_name)
      end
    end

    # Public: Pull the latest changes for the checked-out branch
    def pull
      if_clean do
        command('pull')
      end
    end

    # Public: Create a new branch from the given source
    #
    # new_branch_name - The name of the branch to create
    # source_branch_name - The name of the branch to branch from
    def new_branch(new_branch_name, source_branch_name)
      git.fetch
      command('branch', ['--no-track', new_branch_name, "origin/#{source_branch_name}"])
      new_branch = branch(new_branch_name)
      new_branch.checkout
      command('push', ['-u', 'origin', new_branch_name])
    end

    # Public: Delete the given branch
    #
    # branch_name - The name of the branch to delete
    def delete_branch(branch_name)
      branch = branch_name.is_a?(::Git::Branch) ? branch_name : git.branch(branch_name)
      git.push('origin', ":#{branch}")
      branch.delete
    end

    # Public: The list of branches on GitHub
    #
    # Returns an Array of Strings containing the branch names
    def remote_branches
      git.fetch
      git.branches.remote.map{ |branch| git.branch(branch.name) }.sort_by(&:name)
    end

    # Public: List of branches starting with the given string
    #
    # prefix - String to match branch names against
    #
    # Returns an Array of Branches containing the branch name
    def branches_for(prefix)
      remote_branches.select do |branch|
        branch.name =~ /^#{prefix}/
      end
    end

    # Public: Most recent branch starting with the given string
    #
    # prefix - String to match branch names against
    #
    # Returns an Array of Branches containing the branch name
    def latest_branch_for(prefix)
      branches_for(prefix).last || raise(NoBranchOfType, "No #{prefix} branch")
    end


    # Public: Whether the Git index is clean (has no uncommited changes)
    #
    # Returns a Boolean
    def clean?
      command('status', '--short').empty?
    end

    # Public: Perform the block if the Git index is clean
    def if_clean(message=DEFAULT_DIRTY_MESSAGE)
      if clean? || prompt.yes?(DIRTY_CONFIRM_MESSAGE)
        yield
      else
        alert_dirty_index message
        exit 1
      end
    end

    # Public: Display the message and show the git status
    def alert_dirty_index(message)
      prompt.say " "
      prompt.say message
      prompt.say " "
      prompt.say command('status')
      raise DirtyIndex
    end

    def prompt(**options)
      require 'tty-prompt'
      TTY::Prompt.new(options)
    end


    # Exceptions
    NotOnBranch = Class.new(StandardError)
    NoBranchOfType = Class.new(StandardError)
    DirtyIndex = Class.new(StandardError)
  end
end