#!/usr/bin/env bash
# common.sh - shared helpers. Sourced by bootstrap.sh, not run directly.

# Exported once so we never rely on the `$SUDO VAR=val cmd` pattern, which
# breaks when $SUDO is empty (running as root): the var assignment gets parsed
# before $SUDO expands, so `DEBIAN_FRONTEND=...` ends up treated as a command.
export DEBIAN_FRONTEND=noninteractive

# ---- colors / logging -------------------------------------------------------
if [[ -t 1 ]]; then
  C_RESET=$'\e[0m'; C_DIM=$'\e[2m'; C_RED=$'\e[31m'; C_GRN=$'\e[32m'
  C_YLW=$'\e[33m'; C_BLU=$'\e[34m'; C_BOLD=$'\e[1m'
else
  C_RESET=""; C_DIM=""; C_RED=""; C_GRN=""; C_YLW=""; C_BLU=""; C_BOLD=""
fi

log()   { printf '%s[*]%s %s\n'  "$C_BLU" "$C_RESET" "$*"; }
ok()    { printf '%s[+]%s %s\n'  "$C_GRN" "$C_RESET" "$*"; }
warn()  { printf '%s[!]%s %s\n'  "$C_YLW" "$C_RESET" "$*" >&2; }
err()   { printf '%s[x]%s %s\n'  "$C_RED" "$C_RESET" "$*" >&2; }
die()   { err "$*"; exit 1; }
step()  { printf '\n%s== %s ==%s\n' "$C_BOLD" "$*" "$C_RESET"; }

# ---- privilege --------------------------------------------------------------
# Sets $SUDO to "sudo" if not root, "" if root. Fails if neither works.
detect_sudo() {
  if [[ $EUID -eq 0 ]]; then
    SUDO=""
  elif command -v sudo >/dev/null 2>&1; then
    SUDO="sudo"
    # prime the credential cache early so prompts don't appear mid-run
    $SUDO -v || die "sudo authentication failed"
  else
    die "not root and sudo not available"
  fi
}

# ---- distro detection -------------------------------------------------------
# Sets DISTRO_ID (debian/ubuntu/...), DISTRO_LIKE, DISTRO_CODENAME, PKG_MGR.
detect_distro() {
  [[ -r /etc/os-release ]] || die "/etc/os-release missing - unsupported system"
  # shellcheck disable=SC1091
  . /etc/os-release
  DISTRO_ID="${ID:-unknown}"
  # shellcheck disable=SC2034  # used in bootstrap.sh main()
  DISTRO_LIKE="${ID_LIKE:-}"
  DISTRO_CODENAME="${VERSION_CODENAME:-}"

  if command -v apt-get >/dev/null 2>&1; then
    PKG_MGR="apt"
  elif command -v dnf >/dev/null 2>&1; then
    PKG_MGR="dnf"
  elif command -v pacman >/dev/null 2>&1; then
    PKG_MGR="pacman"
  else
    die "no supported package manager found (apt/dnf/pacman)"
  fi
  ok "detected ${DISTRO_ID} ${DISTRO_CODENAME:-} (pkg: ${PKG_MGR})"
}

# ---- package helpers (apt-focused, dnf/pacman best-effort) ------------------
APT_UPDATED=0
pkg_refresh() {
  case "$PKG_MGR" in
    apt)
      if [[ $APT_UPDATED -eq 0 ]]; then
        log "apt-get update"
        # a single broken third-party repo shouldn't abort the whole bootstrap;
        # downstream installs will fail loudly if a needed pkg is truly missing.
        $SUDO apt-get update -qq || warn "apt-get update reported errors (broken repo?) - continuing"
        APT_UPDATED=1
      fi
      ;;
    dnf)    $SUDO dnf -q makecache ;;
    pacman) $SUDO pacman -Sy --noconfirm >/dev/null ;;
  esac
}

# is a binary already on PATH?
have() { command -v "$1" >/dev/null 2>&1; }

# install one or more packages, skipping any already-present *packages*
pkg_install() {
  pkg_refresh
  case "$PKG_MGR" in
    apt)
      $SUDO apt-get install -y -qq \
        --no-install-recommends "$@" ;;
    dnf)    $SUDO dnf install -y "$@" ;;
    pacman) $SUDO pacman -S --needed --noconfirm "$@" ;;
  esac
}

# install a package only if a given command is missing. usage: ensure_cmd <cmd> <pkg...>
ensure_cmd() {
  local cmd="$1"; shift
  if have "$cmd"; then
    printf '%s    - %s already present%s\n' "$C_DIM" "$cmd" "$C_RESET"
    return 0
  fi
  log "installing ${cmd} (pkg: $*)"
  pkg_install "$@"
}

# write file from stdin only if content differs (idempotent). usage: write_if_changed <path>
write_if_changed() {
  local target="$1" tmp
  tmp="$(mktemp)"
  cat > "$tmp"
  if [[ -f "$target" ]] && cmp -s "$tmp" "$target"; then
    rm -f "$tmp"
    return 1   # unchanged
  fi
  $SUDO install -D -m "${2:-0644}" "$tmp" "$target"
  rm -f "$tmp"
  return 0     # changed
}