#!/usr/bin/env bash
# setup-bind.sh — initialize BIND for the DNS Web Manager
#
# Detects BIND layout (Debian/Ubuntu vs RHEL/CentOS/Rocky) by checking which
# files exist, then ensures:
#   - bind package installed
#   - zone directory exists with correct ownership
#   - named.conf.local is included from named.conf
#   - /etc/named.conf.local (or /etc/bind/named.conf.local) exists & writable
#
# Usage:
#   sudo bash scripts/setup-bind.sh          # actually run all steps
#   sudo bash scripts/setup-bind.sh --dry-run # print what would run, don't execute
#
# Idempotent: safe to run multiple times. Existing configs are preserved;
# named.conf.local is only created if missing.

set -euo pipefail

DRY_RUN=0
if [[ "${1:-}" == "--dry-run" ]]; then
    DRY_RUN=1
fi

# ─── helpers ────────────────────────────────────────────────────────────────
log()  { printf '\033[1;34m[setup-bind]\033[0m %s\n' "$*"; }
warn() { printf '\033[1;33m[setup-bind]\033[0m %s\n' "$*" >&2; }
err()  { printf '\033[1;31m[setup-bind]\033[0m %s\n' "$*" >&2; }

run() {
    if [[ $DRY_RUN -eq 1 ]]; then
        printf '  [DRY-RUN] %s\n' "$*"
    else
        "$@"
    fi
}

must_be_root() {
    if [[ $EUID -ne 0 ]]; then
        err "Must run as root (use sudo)"
        exit 1
    fi
}

# ─── detect BIND layout ─────────────────────────────────────────────────────
# Logic mirrors app.py's auto-detection: prefer RHEL paths when both exist.
detect_layout() {
    if [[ -d /etc/bind ]]; then
        # Debian/Ubuntu bind9 — /etc/bind exists
        BIND_USER="bind"
        BIND_GROUP="bind"
        ZONES_DIR="/etc/bind/zones"
        NAMED_CONF="/etc/bind/named.conf"
        NAMED_CONF_LOCAL="/etc/bind/named.conf.local"
        PKG_MANAGER="apt-get"
        PKG_INSTALL=(apt-get install -y bind9 bind9utils dnsutils)
        SERVICE_NAME="named"
    elif [[ -f /etc/named.conf ]]; then
        # RHEL/CentOS/Rocky bind — /etc/named.conf exists, /etc/bind usually doesn't
        BIND_USER="named"
        BIND_GROUP="named"
        ZONES_DIR="/var/named"
        NAMED_CONF="/etc/named.conf"
        NAMED_CONF_LOCAL="/etc/named.conf.local"
        PKG_MANAGER="yum"
        PKG_INSTALL=(yum install -y bind bind-utils)
        SERVICE_NAME="named"
    else
        # No BIND config found at all — assume Debian (most common for fresh installs)
        # and let the package install create the structure.
        BIND_USER="bind"
        BIND_GROUP="bind"
        ZONES_DIR="/etc/bind/zones"
        NAMED_CONF="/etc/bind/named.conf"
        NAMED_CONF_LOCAL="/etc/bind/named.conf.local"
        PKG_MANAGER="apt-get"
        PKG_INSTALL=(apt-get install -y bind9 bind9utils dnsutils)
        SERVICE_NAME="named"
        warn "No BIND config detected; defaulting to Debian/Ubuntu layout"
    fi

    log "Detected layout:"
    log "  bind user/group : $BIND_USER:$BIND_GROUP"
    log "  zones dir       : $ZONES_DIR"
    log "  named.conf      : $NAMED_CONF"
    log "  named.conf.local: $NAMED_CONF_LOCAL"
    log "  pkg manager     : $PKG_MANAGER"
}

# ─── steps ──────────────────────────────────────────────────────────────────
install_bind() {
    log "Step 1: ensure BIND package is installed"
    if command -v named >/dev/null 2>&1; then
        log "  named already installed: $(named -v 2>&1 | head -1)"
        return
    fi
    warn "  named not found; installing via $PKG_MANAGER"
    run "${PKG_INSTALL[@]}"
}

ensure_zones_dir() {
    log "Step 2: ensure zones directory exists with correct ownership"
    if [[ ! -d "$ZONES_DIR" ]]; then
        log "  $ZONES_DIR does not exist; creating"
        run mkdir -p "$ZONES_DIR"
    else
        log "  $ZONES_DIR already exists"
    fi
    # group-writable + setgid so future files inherit the group
    run chown "$BIND_USER:$BIND_GROUP" "$ZONES_DIR"
    run chmod 2770 "$ZONES_DIR"
}

ensure_named_conf_local() {
    log "Step 3: ensure named.conf.local exists and is writable by web"
    if [[ ! -f "$NAMED_CONF_LOCAL" ]]; then
        log "  $NAMED_CONF_LOCAL does not exist; creating empty file"
        run touch "$NAMED_CONF_LOCAL"
        run chown "root:$BIND_GROUP" "$NAMED_CONF_LOCAL"
        run chmod 640 "$NAMED_CONF_LOCAL"
    else
        log "  $NAMED_CONF_LOCAL already exists; preserving"
        # Don't change ownership if file already has content — it may be managed
        # by someone else. Just make sure web process can write to it.
        run chmod 644 "$NAMED_CONF_LOCAL"
    fi
}

ensure_include_in_named_conf() {
    log "Step 4: ensure named.conf includes named.conf.local"
    if [[ ! -f "$NAMED_CONF" ]]; then
        warn "  $NAMED_CONF not found; skipping include check (bind not configured?)"
        return
    fi
    if grep -qF "$NAMED_CONF_LOCAL" "$NAMED_CONF"; then
        log "  $NAMED_CONF already includes $NAMED_CONF_LOCAL"
        return
    fi
    warn "  $NAMED_CONF does NOT include $NAMED_CONF_LOCAL — appending"
    if [[ $DRY_RUN -eq 1 ]]; then
        printf '  [DRY-RUN] echo "include \\"%s\\";" >> %s\n' "$NAMED_CONF_LOCAL" "$NAMED_CONF"
    else
        printf '\ninclude "%s";\n' "$NAMED_CONF_LOCAL" >> "$NAMED_CONF"
    fi
}

restart_named() {
    log "Step 5: restart named so include takes effect"
    if ! systemctl is-active --quiet "$SERVICE_NAME"; then
        warn "  $SERVICE_NAME not running; skipping restart"
        return
    fi
    if [[ $DRY_RUN -eq 1 ]]; then
        printf '  [DRY-RUN] systemctl restart %s\n' "$SERVICE_NAME"
    else
        run systemctl restart "$SERVICE_NAME"
        sleep 1
        if systemctl is-active --quiet "$SERVICE_NAME"; then
            log "  $SERVICE_NAME is active"
        else
            err "  $SERVICE_NAME failed to start; check 'journalctl -xe -u $SERVICE_NAME'"
        fi
    fi
}

# ─── main ───────────────────────────────────────────────────────────────────
main() {
    must_be_root
    detect_layout
    if [[ $DRY_RUN -eq 1 ]]; then
        log "DRY-RUN mode: no changes will be made"
    fi
    install_bind
    ensure_zones_dir
    ensure_named_conf_local
    ensure_include_in_named_conf
    restart_named
    log "Done. Verify with:"
    log "  named-checkconf"
    log "  rndc status | grep 'number of zones'"
}

main "$@"