#!/usr/bin/env bash

# TODO check for duplicate lines in bindings

set -e

newline=$'\n'
esc=$'\e'
csi="$esc["
reset="${csi}0m"

bold="${csi}1m"
dim="${csi}2m"

default="${csi}39m"
red="${csi}31m"
green="${csi}32m"
yellow="${csi}33m"


##### STATUS #####


status_buffer=""
status_source_active=""
status_count_total=0
status_count_managed=0
status_count_unmanaged=0
status_count_nonexistent=0

status_target_begin() {
    status_buffer=""
    status_source_active=""
}

status_target_end() {
    tilde_expanded_target=${1/\~/$HOME}

    if [ ! -z $status_source_active ] ; then
        status_buffer="${bold}${green}*${default} $1${reset}${status_buffer}"
        ((status_count_managed=status_count_managed+1))
    else
        if [ -e $tilde_expanded_target ] ; then
            status_buffer="${yellow}*${default} $1${status_buffer}"
            ((status_count_unmanaged=status_count_unmanaged+1))
        else
            status_buffer="${dim}* $1${reset}${status_buffer}"
            ((status_count_nonexistent=status_count_nonexistent+1))
        fi
    fi

    echo "$status_buffer"
    echo

    ((status_count_total=status_count_total+1))
}

status_target_source() {
    tilde_expanded_target=${1/\~/$HOME}

    if [ -L $tilde_expanded_target ] ; then
        if [ $(readlink $tilde_expanded_target) = "${PWD}/$2" ] ; then
            status_source_active="y"
            status_buffer="${status_buffer}${newline}  $2"
        else
            status_buffer="${status_buffer}${newline}  ${dim}$2${reset}"
        fi
    else
        status_buffer="${status_buffer}${newline}  ${dim}$2${reset}"
    fi

}

status_finished() {
    cat <<EOF
${bold}${status_count_total}${reset} targets, \
${bold}${status_count_managed}${reset} managed, \
${bold}${status_count_unmanaged}${reset} unmanaged, \
${bold}${status_count_nonexistent}${reset} non-existent
EOF
}


##### INSTALL #####


install_target_source() {
    tilde_expanded_target=${1/\~/$HOME}

    if [ -z $install_done ] && [ $tilde_expanded_target = $install_target ] ; then
        # if no source is provided, select the first option, otherwise
        # check for a match
        if [ -z $install_source ] || [ $install_source = $2 ] ; then
            echo "${dim}$ ln -sf ${PWD}/$2 $tilde_expanded_target${reset}"
            ln -sf "${PWD}/$2" "$tilde_expanded_target"
            install_done="y"
        fi
    fi
}

install_finished() {
    if [ -z $install_done ] ; then
        echo "${bold}${red}error${reset}: no suitable target/source combination found."
        exit 1
    fi
}


##### PROCESS INTERFACE #####


# start processing a target
#
# expects 1 argument: target path
process_target_begin() {
    case $mode in
        ("status")
            status_target_begin $1
            ;;
        ("install")
            true
            ;;
        (*)
            echo "Invalid mode: '$mode'"
            exit 1
            ;;
    esac
}

# stop processing a target
#
# expects 1 argument: target path
process_target_end() {
    case $mode in
        ("status")
            status_target_end $1
            ;;
        ("install")
            true
            ;;
        (*)
            echo "Invalid mode: '$mode'"
            exit 1
            ;;
    esac
}

# process a target and source pair
#
# expects 2 argument: target path, source path
process_target_source() {
    case $mode in
        ("status")
            status_target_source $1 $2
            ;;
        ("install")
            install_target_source $1 $2
            ;;
        (*)
            echo "Invalid mode: '$mode'"
            exit 1
            ;;
    esac

}

# finish processing
#
# expects no arguments
process_finished() {
    case $mode in
        ("status")
            status_finished
            ;;
        ("install")
            install_finished
            ;;
        (*)
            echo "Invalid mode: '$mode'"
            exit 1
            ;;
    esac

}


##### MAIN #####

case $1 in
    (""|"status")
        mode="status"
        ;;
    ("install")
        mode="install"

        if [ -z $2 ] ; then
            echo "usage: manage.sh install [target] (source)"
            exit 1
        fi

        install_target=$2
        install_source=$3

        ;;
    *)
        echo "Unrecognized command: '$1'"
        exit 1
        ;;
esac


bindings_file="bindings"

line_nr=1
target_file=""

while read -r line ; do
    case $line in
        ("-> "*)
            if [ -z $target_file ] ; then
                echo "Parsing error: source given without target at line $line_nr"
                exit 1
            fi

            source_file=${line#"-> "}

            process_target_source $target_file $source_file
            ;;
        ("")
            if [ ! -z $target_file ] ; then
                process_target_end $target_file
            fi

            target_file=""
            ;;
        (*)
            target_file=$line

            process_target_begin $target_file
            ;;
    esac

    # echo $line
    ((line_nr=line_nr+1))
done < "$bindings_file"

# process last item
if [ ! -z $target_file ] ; then
    process_target_end $target_file
fi

process_finished