#!/usr/bin/env bash

# When under a git repository this script adds the bash prompt indicators about
# the repository status.
#
# the status includes the current branch and colored circles that have the
# following meaning:
# Green: there are staged changes,
# Yellow: if there are unstaged changes
# Red: if there are new untracked-yet-unignored files
#
# The idea for this script came from:
# http://briancarper.net/blog/570/git-info-in-your-zsh-prompt
#
# Author: Daniel Chcouri <333222@gmail.com>; http://www.blogy.me/
# License: GPL2

# Colors definitions
black=$(tput setaf 0)
bold_black=$(tput setaf 0; tput bold)
red=$(tput setaf 1)
bold_red=$(tput setaf 1; tput bold)
green=$(tput setaf 2)
bold_green=$(tput setaf 2; tput bold)
yellow=$(tput setaf 3)
bold_yellow=$(tput setaf 3; tput bold)
blue=$(tput setaf 4)
bold_blue=$(tput setaf 4; tput bold)
magenta=$(tput setaf 5)
bold_magenta=$(tput setaf 5; tput bold)
cyan=$(tput setaf 6)
bold_cyan=$(tput setaf 6; tput bold)
white=$(tput setaf 7)
bold_white=$(tput setaf 7; tput bold)

reset_colors=$(tput sgr0)

# git.is_rep(path=".")
#
# Gets a path and returns 0 if it's under a git repository; 1 otherwise
#
# If under git repository it prints the path to the .git dir to stdout
# function current_branch() {
#   ref=$(git symbolic-ref HEAD 2> /dev/null) || return
#   echo ${ref#refs/heads/}
# }
git.is_rep ()
{
    local path="${1:-.}"

    # First, get the path's absolute path
    cd "$path"
    path="$(pwd -P)/"
    cd - > /dev/null

    while [[ "$path" != '' ]]
    do
        if [[ -e "${path}.git" ]]
        then
            echo "${path}.git"
            return 0
        fi

        if [[ "$path" == '/' ]]
        then
            return 1
        else
            path="${path%/*/}/"
        fi
    done
}

# git.current_branch()
#
# echo the current git branch
#
# return 1 if not under a git repository, 2 if branch is detached or unknown
git.current_branch ()
{
    local dot_git_path branch

    if ! dot_git_path="$(git.is_rep)"
    then
        return 1
    fi

    # The following was forked from:
    # http://aaroncrane.co.uk/2009/03/git_branch_prompt/
    head=$(< "$dot_git_path/HEAD")
    if [[ $head == ref:\ refs/heads/* ]]; then
        branch="${head#*/*/}"
        echo "$branch"
        return 0
    elif [[ $head != '' ]]; then
        branch='detached'
        echo "$branch"
        return 2
    else
        branch='unknown'
        echo "$branch"
        return 2
    fi
}

# git.current_branch()
#
# return a list of space-separated booleans that represent the current git
# status
#
# Meaning of each position:
# 0 untracked
# 1 updated in index
# 2 added to index
# 3 deleted from index
# 4 renamed in index
# 5 copied in index
# 6 work tree changed since index
# 7 deleted in work tree
# 8 unmerged, both deleted
# 9 unmerged, added by us
# 10 unmerged, deleted by them
# 11 unmerged, added by them
# 12 unmerged, deleted by us
# 13 unmerged, both added
# 14 unmerged, both modified
git.status ()
{
    local index="$(git status --porcelain 2> /dev/null)"

    local flags=( 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 )

    while IFS= read -r line; do
        case "${line:0:1}"
        in
            # untracked
            "?")
                flags[0]=1
            ;;
            # updated in index
            "M")
                flags[1]=1
            ;;
            # added to index
            "A")
                flags[2]=1
            ;;
            # deleted from index
            "D")
                flags[3]=1
            ;;
            # renamed in index
            "R")
                flags[4]=1
            ;;
            # copied in index
            "D")
                flags[5]=1
            ;;
        esac
        case "${line:1:1}"
        in
            # work tree changed since index
            "M")
                flags[6]=1
            ;;
            # deleted in work tree
            "D")
                flags[7]=1
            ;;
        esac
        case "${line:0:2}"
        in
            # unmerged, both deleted
            "DD")
                flags[8]=1
            ;;
            # unmerged, added by us
            "AU")
                flags[9]=1
            ;;
            # unmerged, deleted by them
            "UD")
                flags[10]=1
            ;;
            # unmerged, added by them
            "UA")
                flags[11]=1
            ;;
            # unmerged, deleted by us
            "DU")
                flags[12]=1
            ;;
            # unmerged, both added
            "AA")
                flags[13]=1
            ;;
            # unmerged, both modified
            "UU")
                flags[14]=1
            ;;
        esac
    done <<< "$index"

    echo "${flags[@]}"

    return 0
}

prompt_command_git_status ()
{
    local result="$bold_blue$(git.current_branch)"
    local status=($(git.status))

    if (( ${status[1]} == 1 )) || (( ${status[2]} == 2 )) || (( ${status[3]} == 3 )) || (( ${status[4]} == 4 )) || (( ${status[5]} == 5 ))
    then
        #echo "staged changes"
        result+="$bold_green●$reset_colors"
    fi
    if (( ${status[6]} == 1 )) || (( ${status[7]} == 1 ))
    then
        #echo "unstaged changes"
        result+="$bold_yellow●$reset_colors"
    fi
    if (( ${status[0]} == 1 ))
    then
        #echo "untracked changes"
        result+="$bold_red●$reset_colors"
    fi

    echo "$result"
}


export original_ps="$PS1"
PROMPT_COMMAND+="$(cat <<EOF

    if git.is_rep > /dev/null
    then
        export PS1="$bold_green\u@\h $bold_blue\W [$reset_colors\$(prompt_command_git_status)$bold_blue] \$ $reset_colors"
    else
        export PS1="\$original_ps"
    fi
EOF
)"

# vim:ft=bash: