#!/usr/bin/env bash
#
# temp-env.sh
# Spin up a throwaway Debian container, install packages, drop into a shell,
# and clean up automatically when you exit.

set -euo pipefail

# ---- colors ----
BOLD='\033[1m'
CYAN='\033[0;36m'
GREEN='\033[0;32m'
YELLOW='\033[0;33m'
RED='\033[0;31m'
NC='\033[0m'

info()  { echo -e "${CYAN}==>${NC} $1"; }
ok()    { echo -e "${GREEN}✔${NC} $1"; }
warn()  { echo -e "${YELLOW}!${NC} $1"; }
err()   { echo -e "${RED}✘${NC} $1"; }

# ---- sanity checks ----
if ! command -v docker &>/dev/null; then
    err "Docker isn't installed or isn't on PATH."
    exit 1
fi

echo -e "${BOLD}Ephemeral Debian Environment${NC}"
echo "--------------------------------"

# ---- pick a debian tag ----
read -rp "$(echo -e "${CYAN}?${NC} Debian tag [bookworm]: ")" TAG
TAG="${TAG:-bookworm}"
IMAGE="debian:${TAG}"

# ---- packages to install ----
read -rp "$(echo -e "${CYAN}?${NC} Packages to install (space-separated, blank for none): ")" PACKAGES

# ---- optional extra apt flags ----
read -rp "$(echo -e "${CYAN}?${NC} Extra apt-get flags (e.g. --no-install-recommends) [none]: ")" APT_FLAGS

# ---- mount a local dir? ----
read -rp "$(echo -e "${CYAN}?${NC} Mount a local directory into the container? (path or blank): ")" MOUNT_DIR
MOUNT_ARGS=()
if [[ -n "$MOUNT_DIR" ]]; then
    if [[ -d "$MOUNT_DIR" ]]; then
        MOUNT_ARGS=(-v "$(realpath "$MOUNT_DIR"):/mnt/host")
        ok "Will mount $(realpath "$MOUNT_DIR") -> /mnt/host"
    else
        warn "Directory '$MOUNT_DIR' doesn't exist, skipping mount."
    fi
fi

# ---- remove image after exit too? ----
read -rp "$(echo -e "${CYAN}?${NC} Remove the image (${IMAGE}) after exiting, not just the container? [y/N]: ")" RM_IMAGE
RM_IMAGE="${RM_IMAGE:-n}"

# ---- build the in-container command ----
if [[ -n "$PACKAGES" ]]; then
    INNER_CMD="apt-get update && apt-get install -y ${APT_FLAGS} ${PACKAGES} && bash"
else
    INNER_CMD="apt-get update && bash"
fi

echo
info "Image:      ${IMAGE}"
info "Packages:   ${PACKAGES:-<none>}"
info "Command:    ${INNER_CMD}"
[[ -n "$MOUNT_DIR" && -d "$MOUNT_DIR" ]] && info "Mount:      $(realpath "$MOUNT_DIR") -> /mnt/host"
echo

read -rp "$(echo -e "${CYAN}?${NC} Launch now? [Y/n]: ")" CONFIRM
CONFIRM="${CONFIRM:-y}"
if [[ ! "$CONFIRM" =~ ^[Yy] ]]; then
    warn "Aborted."
    exit 0
fi

info "Pulling/starting container (this shell disappears on exit, --rm is set)..."
echo "--------------------------------"

set +e
docker run --rm -it "${MOUNT_ARGS[@]}" "$IMAGE" bash -c "$INNER_CMD"
EXIT_CODE=$?
set -e

echo "--------------------------------"
ok "Container exited (code ${EXIT_CODE}) and was automatically removed."

if [[ "$RM_IMAGE" =~ ^[Yy] ]]; then
    info "Checking if any other containers still use ${IMAGE}..."
    IN_USE=$(docker ps -a --filter ancestor="$IMAGE" -q)
    if [[ -n "$IN_USE" ]]; then
        warn "Other containers still reference ${IMAGE}, skipping removal:"
        docker ps -a --filter ancestor="$IMAGE"
    else
        docker rmi "$IMAGE" && ok "Removed image ${IMAGE}."
    fi
fi

ok "Done."