#!/usr/bin/env bash
# ─────────────────────────────────────────────────────────────────────────────
# Arcline OS — overlay application
#
#   scripts/apply-overlays.sh <rootfs> <edition>
#
# overlays/ is organised as layered filesystem trees:
#     overlays/base/<abs path>            → every edition
#     overlays/<edition>/<abs path>       → that edition only
#
# Files are copied preserving structure and permissions. Later layers win.
# overlays/base is applied first, then the edition overlay.
# ─────────────────────────────────────────────────────────────────────────────
set -euo pipefail
source "$(dirname "${BASH_SOURCE[0]}")/common.sh"

TARGET="${1:?usage: apply-overlays.sh <rootfs> <edition>}"
EDITION="${2:?usage: apply-overlays.sh <rootfs> <edition>}"
validate_edition "$EDITION"

[[ -d "$TARGET" ]] || die "rootfs '$TARGET' does not exist"

apply_layer() {
  local layer="$1"
  local src="$ROOT/overlays/$layer"
  [[ -d "$src" ]] || { warn "overlay layer '$layer' not present, skipping"; return 0; }
  log "applying overlay layer: $layer"
  # Copy the *contents* of the layer dir into the rootfs, keeping dotfiles,
  # symlinks, and permissions. Never clobber across layers silently — but
  # cp -a with overwrite is the desired "later layer wins" behaviour here.
  cp -a "$src/." "$TARGET/"
}

apply_layer base
apply_layer "$EDITION"
log "overlays applied ✓"