install

#!/bin/bash

# External Environment variables that affect behaviour:
#  - DOTFILES_OVERWRITE_REPLY
#       Set to one of ynq as the reply to use in case of overwriting files.
#       y: yes
#       n: no
#       q: quit
#  - DOTFILES_SKIP_VIM_PLUGINS
#       Set to 1 to prevent VIM from opening and installing all plugins, as
#       can be a lengthy process.
#  - DOTFILES_CHANGES_REPORT
#       If set, the count of changed files will be written to this file

DOTFILES_OVERWRITE_REPLY=
DOTFILES_SKIP_VIM_PLUGINS=
DOTFILES_CHANGES_REPORT=

INSTALLER_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" &>/dev/null && pwd)"
THIS_SCRIPT="$(basename "$0")"
declare -a CHANGED_FILES

## Download all vim plug-ins
get_vim_plugins()
{
    echo "Installing Vim Plugins"
    vim +PlugUpgrade +qa || { echo 'Error upgrading Plug. Will continue.'; }
    if [[ $DOTFILES_SKIP_VIM_PLUGINS -eq 1 ]]
    then
        echo "Skipping Vim plugins installation"
        return
    fi
    vim +PlugInstall +qa || { echo 'Error installing vim plugins'; return 1; }
}

## Run xmodmap with the customisations in ~/.Xmodmap
apply_xmodmap()
{
    if [[ -e ~/.Xmodmap ]] && has_program xmodmap; then
        echo "Applying custom key bindings"
        xmodmap ~/.Xmodmap || true
    fi
}

post_install_actions()
{
    get_vim_plugins
    if sys::is_linux; then
        apply_xmodmap
    fi
}

install_files_from()
{
    local src_dir="$1"
    local dest_dir="$2"
    shift 2

    # Include the platform directories in the excluded list, as they are
    # treated separately below.
    local -a excluded=("$@" _linux _macos)
    replace_all=false
    cd "$src_dir" || die "Could not change to $src_dir"

    local file
    for file in *; do
        if ! element_exists "$file" "${excluded[@]}"; then
            local dest_file_name
            dest_file_name=$(basename "$file" .tpl)
            local dest_file_path="$dest_dir/.$dest_file_name"
            install_file "$file" "$dest_file_path"
        fi
    done

    # Install platform specific files
    if [[ -d "$src_dir/_linux" ]] && sys::is_linux; then
        install_files_from "$src_dir/_linux" "$dest_dir" "${excluded[@]}"
    fi

    if [[ -d "$src_dir/_macos" ]] && sys::is_macos; then
        install_files_from "$src_dir/_macos" "$dest_dir" "${excluded[@]}"
    fi

}
# Install the dot files into user's home directory
install_home()
{
    local -a excluded=("$THIS_SCRIPT" README.mkd README README.md LICENSE TODO.mkd)
    install_files_from "$INSTALLER_DIR" "$HOME" "$THIS_SCRIPT" "${excluded[@]}"
    post_install_actions
    echo "Installation complete. Changed files: ${#CHANGED_FILES[@]}"
    if [[ -n $DOTFILES_CHANGES_REPORT ]]; then
        echo "${#CHANGED_FILES[@]}" > "$DOTFILES_CHANGES_REPORT"
    fi
}

overwrite_confirmation()
{
    local dest=$1
    if [[ -n $DOTFILES_OVERWRITE_REPLY ]]
    then
        REPLY=$DOTFILES_OVERWRITE_REPLY
    else
        read -r -p "overwrite ${dest}? [ynaq] "
    fi
}


## Install a file (with replacement confirmation)
install_file()
{
    local file="$1"
    local dest_file_path="$2"

    if [[ -e $dest_file_path ]] || \
       [[ -L $dest_file_path ]]		  # Can be a broken symlink
    then
        if [[ -e $dest_file_path ]] &&
            [[ $(readlink -f "$file") == $(readlink -f "$dest_file_path") ]]
        then
            echo "identical $dest_file_path"
        elif $replace_all
        then
            replace_file "$file" "$dest_file_path"
        else
            overwrite_confirmation "${dest_file_path}"
            case $REPLY in
                'y') replace_file "$file" "$dest_file_path" ;;
                'q') exit 1 ;;
                'a') replace_all=true
                     replace_file "$file" "$dest_file_path" ;;
                *)   echo "skipping $dest_file_path" ;;
            esac
        fi
    else
        link_file "$file" "$dest_file_path"
    fi
}


replace_file()
{
    local file="$1"
    local dest_file_path="$2"

    backup "$dest_file_path"
    link_file "$file" "$dest_file_path"
}


link_file()
{
    local file="$1"
    local dest_file_path="$2"

    if [[ $file =~ \.tpl$ ]]
    then
        local temp_file
        temp_file=$(mktemp /tmp/dotfiles.XXXXXX)
        echo "generating $dest_file_path"
        if ! ( source "$file" > "$temp_file" ); then
            echo "Error generating $dest_file_path"
            rm "$temp_file"
            return 1
        fi
        mv "$temp_file" "$dest_file_path"
    else
        echo "linking $dest_file_path"
        ln -s "$(pwd)/$file" "$dest_file_path"
    fi
    CHANGED_FILES+=("$dest_file_path")
}


element_exists()
{
    local elem="$1"
    shift
    local arr=( "$@" )
    local i

    for i in "${arr[@]}"
    do
        if [[ $i == "$elem" ]]
        then
            return 0
        fi
    done
    return 1
}


backup()
{
    local file="$1"
    local backup_suffix
    backup_suffix="bak.$(date "+%Y%m%d%H%M%S")"
    local backup_file="${file}.${backup_suffix}"
    mv "$file" "$backup_file"
    echo "backed up $file to $backup_file"
}


has_program()
{
    type -t "$1" > /dev/null
}

die()
{
    echo "$*" >&2
    exit 1
}

sys::is_linux() {
    [[ $(uname -s) == Linux ]]
}

sys::is_macos() {
    [[ $(uname -s) == Darwin ]]
}

# Install all configuration files
install_home