#!/usr/bin/env bash
# Pre-flight checks: root, Ubuntu release, RAM and disk.
#
# Network is informational here and never a gate: an offline install takes its
# packages from the local bundle, so it needs neither the Internet nor the
# central endpoint. Three things are reported separately for the operator:
#   1. local network link   — no intent, not used by the install,
#   2. Internet             — NOT required for an offline install (no warning),
#   3. central connection   — not needed during install; that is the enrollment
#                             stage's job.
# This module therefore never fails because a network probe failed.
#
# Idempotent: safe to re-run. Supports --check for read-only verification.
# Exit codes: 0 = OK, 3 = SKIP (optional step, nothing to do), 1 = real failure.
set -euo pipefail

MODULE="01-precheck"
LOG_FILE="${LOG_FILE:-/var/log/blueforce-install.log}"
DEALER_ID="${DEALER_ID:-}"
BF_HOSTNAME="${BF_HOSTNAME:-}"
BF_DEVICE="${BF_DEVICE:-}"
STATE_DIR="${STATE_DIR:-/var/lib/blueforce}"

log() {
    local msg="$1"
    mkdir -p "$(dirname "$LOG_FILE")" 2>/dev/null || true
    echo "$(date -u +%Y-%m-%dT%H:%M:%SZ) [01-precheck] $msg" | tee -a "$LOG_FILE"
}

CHECK_MODE=0
if [[ "${1:-}" == "--check" ]]; then CHECK_MODE=1; fi
MIN_RAM_MB=2048
MIN_DISK_MB=20480

fail() { log "FAIL: $1"; echo "FAIL: $1" >&2; exit 1; }
info() { log "BİLGİ: $1"; }

# Read-only network report. Nothing here can fail the install.
report_network() {
    if ip -o link show up 2>/dev/null | grep -qv ' lo:'; then
        info "yerel ağ: bağlantı var (kurulum için gerekmiyor, kullanılmıyor)"
    else
        info "yerel ağ: bağlantı görünmüyor (kurulum için gerekmiyor, kullanılmıyor)"
    fi
    if [[ "${BF_OFFLINE:-0}" == 1 ]]; then
        # Offline install: no probe at all, and no warning either.
        info "internet: kurulum yerel paket deposundan yapılır; internet GEREKMEZ"
    elif getent hosts archive.ubuntu.com >/dev/null 2>&1; then
        info "internet: erişilebilir (geliştirme/test kipi)"
    else
        info "internet: erişilemiyor (bu kurulum için gerekmez)"
    fi
    info "merkez bağlantısı: kurulum sırasında gerekmez; enrollment aşamasında doğrulanır"
}

run_checks() {
    if [[ "$CHECK_MODE" -eq 0 ]]; then
        [[ "$(id -u)" -eq 0 ]] || fail "must run as root"
    else
        info "yönetici yetkisi: salt-okunur denetim; root gerekmiyor"
    fi
    if [[ -f /etc/os-release ]]; then
        # shellcheck disable=SC1091
        . /etc/os-release
        [[ "${VERSION_ID:-}" == 26.04* ]] || fail "unsupported OS: ${NAME:-unknown} ${VERSION_ID:-unknown} (need Ubuntu 26.04)"
    else
        fail "/etc/os-release not found"
    fi
    local ram_mb disk_mb
    ram_mb=$(awk '/MemTotal/ {printf "%d", $2/1024}' /proc/meminfo)
    [[ "$ram_mb" -ge "$MIN_RAM_MB" ]] || fail "RAM too low: ${ram_mb}MB (need >= ${MIN_RAM_MB}MB)"
    disk_mb=$(df -m / --output=avail | tail -1 | tr -d ' ')
    [[ "$disk_mb" -ge "$MIN_DISK_MB" ]] || fail "disk too low: ${disk_mb}MB free on / (need >= ${MIN_DISK_MB}MB)"
    report_network
    log "OK: ön denetim geçti (Ubuntu ${VERSION_ID}, RAM ${ram_mb}MB, disk ${disk_mb}MB boş; yerel kurulum=$([[ "${BF_OFFLINE:-0}" == 1 ]] && echo evet || echo hayır))"
}

run_checks