#!/usr/bin/env bash

args() {
    while [ -n "$1" ]; do
        case "$1" in
            "-h" | "--help")
                echo "$0 [OPTIONS] -- Dotfile management script"
                echo ""
                echo "options:"
                echo "  -h/--help        Show this dialog"
                echo "  -p/--pretend     Preview changes without application"
                echo "  -u/--uninstall   Uninstall symlinks and restore backups"
                echo "  -n/--no-backup   Do not back up existing directories"
                echo ""
                echo "origin: https://git.caem.dev/caem/dotfiles"
                exit 0
                ;;
            "-p" | "--pretend")
                PRETEND_MODE=1
                ;;
            "-u" | "--uninstall")
                UNINSTALL_MODE=1
                ;;
            "-n" | "--no-backup")
                NO_BACKUP=1
                ;;
            *)
                >&2 echo "Unknown option '$1'. Run with --help for a list of valid options."
                exit 1
                ;;
        esac
        shift
    done
}

install_map=(
    ".emacs.d" "$HOME/.emacs.d"
    ".config/emacs" "$HOME/.config/emacs"
    ".config/fastfetch" "$HOME/.config/fastfetch"
    ".config/ghostty" "$HOME/.config/ghostty"
    ".zshrc" "$HOME/.zshrc"
    ".guile" "$HOME/.guile"
    ".profile" "$HOME/.profile"
)

install() {
    for ((i = 0 ; i < "${#install_map[@]}" ; i += 2)); do
        local src
        src="$(realpath "${install_map[$i]}")"
        local dst="${install_map[$((i + 1))]}"

        if [ "$(readlink "$dst")" = "$(realpath "$src")" ]; then
            echo "Skipping $src as it already is symlinked"
            continue
        fi

        if [ -e "$dst" ]; then
            if [ -n "$NO_BACKUP" ]; then
                >&2 echo "Cannot continue as $dst already exists"
            else
                local backup
                backup="$(basename "$dst")"

                if [[ $backup != "."* ]]; then
                   backup=".${backup}"
                fi
                backup="$(dirname "$dst")/${backup}.backup"

                if [ -e "$backup" ]; then
                    >&2 echo "Cannot continue as backup already exists at $backup"
                    exit 1
                fi

                if [ -z "$PRETEND_MODE" ]; then
                    cp -r "$dst" "$backup"
                fi
                echo "backup $dst -> $backup"
            fi
        fi

        if [ -z "$PRETEND_MODE" ]; then
            rm -rf "$dst"
            ln -s "$(realpath "$src")" "$dst"
        fi
        echo "symlink $dst -> $src"
    done
}

uninstall() {
    for ((i = 0 ; i < "${#install_map[@]}" ; i += 2)); do
        local src
        src="$(realpath "${install_map[$i]}")"
        local dst="${install_map[$((i + 1))]}"

        if [ ! -h "$dst" ]; then
            echo "Skipping $dst as it is not a symlink"
            continue
        fi

        if [ "$(readlink -f "$dst")" = "$(realpath "$src")" ]; then
            if [ -z "$PRETEND_MODE" ]; then
                unlink "$dst"
            fi
            echo "remove link $dst"

            local backup
            backup="$(basename "$dst")"

            if [[ $backup != "."* ]]; then
                backup=".${backup}"
            fi
            backup="$(dirname "$dst")/${backup}.backup"

            if [ -e "$backup" ]; then
                if [ -z "$PRETEND_MODE" ]; then
                    mv "$backup" "$dst"
                fi
                echo "restore $backup -> $dst"
            fi
        else
            echo "Skipping $dst as it is not symlinked"
            continue
        fi
    done
}

main() {
    args "$@"
    if [ -n "$PRETEND_MODE" ]; then
        echo "(pretend)"
    fi

    if [ -z "$UNINSTALL_MODE" ]; then
        install
    else
        uninstall
    fi
}

set -e
main "$@"