#!/bin/bash
# sti --- Stupid Tool Installer

data_home="${XDG_DATA_HOME:-${HOME}/.local/share}/sti"
bin_home="${HOME}/usr/bin"

function fold () { /usr/bin/fold -s -w $(tput cols); }
function find-executables ()
{
    find "$1" -type f -executable \! -wholename "${data_home}/*/.*"
}

function help_help { cmd_help "$@"; }
function cmd_help
{
    local xname="$(basename $0)"

    if [[ -n "$1" ]]; then
        local prefix="help"
        dispatch "$@"
    else
        echo "Usage: $xname <command> ARG"
        echo
        echo "Commands include: "
        echo "  help     Show this help message"
        echo "  install  Install a tool from a git repository"
        echo "  reinit   Retry installing the executables of a tool"
        echo "  remove   Remove an installed tool"
        echo
        echo "You can use \`$xname help <command>' to get more \
information about a command." | fold
    fi
}

function help_reinit ()
{
    local xname="$(basename 0)"

    echo "Usage: ${xname} reinit TOOL"
    echo
    echo "TOOL should be the name of a tool installed previously with \
\`${xname} install'. This name is the base name of the URL used to \
install the tool, with the \`.git' suffix removed." | fold
    echo
    echo "Each executable file found in the tool's directory is checked \
to see if it exists in ${bin_home}, it reports whether it is already \
installed or doesn't belong to the tool. If it doesn't exist a symlink \
is created in ${bin_home}." | fold
}

function cmd_reinit ()
{
    local tool_home="${data_home}/tools/$1"

    if [[ -d "$tool_home" ]]; then
        for exe in $(find-executables "$tool_home"); do
            local executable_name=$(basename "$exe")
            local destination="${bin_home}/${executable_name}"

            if [[ ! -e "$destination" ]]; then
                ln -s "$exe" "$destination"
            elif [[ "$(readlink $destination)" == "$exe" ]]; then
                echo "Executable ${executable_name} already installed"
            else
                echo "Executable ${executable_name} already exists in \
${bin_home}"
            fi
        done
    fi
}

function help_install ()
{
    local xname="$(basename $0)"

    echo "Usage: ${xname} install URL"
    echo
    echo "URL should be a valid argument to \`git clone'."
    echo
    echo "URL is cloned and for each executable file found in the \
resulting directory a symlink is created in ${bin_home}. If there is \
already a file with the same name, no symlink is created and a message \
is displayed." | fold
}

function cmd_install ()
{
    tool_name=$(basename $1 .git)
    tool_home="${data_home}/tools/${tool_name}"

    # Ensure the bin directory exists.
    if [[ ! -d "$bin_home" ]]; then
        echo "Creating directory ${bin_home}"
        mkdir -p "$bin_home"
    fi

    if [[ ! -d "$tool_home" ]]; then
        git clone $1 "$tool_home"
        cmd_reinit "$tool_name"
    else
        echo "Tool ${tool_name} already installed"
        exit 2
    fi
}

function help_remove ()
{
    local xname="$(basename $0)"

    echo "Usage: ${xname} remove TOOL"
    echo
    echo "TOOL should be the name of a tool installed previously with \
\`${xname} install'. This name is the base name of the URL used to \
install the tool, with the \`.git' suffix removed." | fold
    echo
    echo "Any executable files found in the directory of TOOL will have \
their symlinks in ${bin_home} removed. If a file exists with the same \
name as one of the symlinks should have and it is not a symlink to one \
of TOOL's executables, it is not removed and a message is displayed." \
    | fold
}

function cmd_remove ()
{
    tool_home="${data_home}/tools/$1"

    if [[ -d "$tool_home" ]]; then
        for exe in $(find-executables "$tool_home"); do
            local real_path=$(realpath "$exe")
            local base_name=$(basename "$exe")
            local link_path="${bin_home}/${base_name}"
            local linked_path=$(readlink "$link_path")

            if [[ -e "$link_path" ]] \
               && [[ "$linked_path" == "$real_path" ]]; then
                rm "$link_path"
            else
                echo "Executable ${base_name} is not part of $1"
            fi
        done
        rm -rf "$tool_home" && echo "Succesfully removed $1"
    else
        echo "Tool $1 is not installed"
        exit 2
    fi
}

function dispatch
{
    local name="${prefix-cmd}_$1"

    if [[ $(type -t "$name") == "function" ]]; then
        shift
        "$name" "$@"
    else
        echo "Unknown command: $1"
        exit 1
    fi
}

if [[ ${#@} -lt 1 ]]; then
    cmd_help "$@"
    exit 1
else
    dispatch "$@"
fi