#!/usr/bin/env bash
set -euo pipefail
# POS: share nfs-client — Mount NFS shares (ephemeral or persistent systemd mount units)

source "$(dirname "$0")/../lib/common.sh" 2>/dev/null || source "$(dirname "$0")/common.sh"
source "$(dirname "$0")/../lib/notify.sh" 2>/dev/null || source "$(dirname "$0")/notify.sh"

command -v mount.nfs &>/dev/null || err "mount.nfs not found (install nfs-common)"
command -v systemd-escape &>/dev/null || err "systemd-escape not found"

usage() {
    cat <<EOF
Usage: pos share nfs-client <command> [args]

Mount and manage NFS shares from remote servers (nfs-common).

Commands:
  mount <server:export> <local-dir>    One-shot mount (creates local-dir if needed)
  unmount <local-dir>                   Unmount the share
  list                                  Show active NFS mounts
  persist <server:export> <local-dir>   Persistent mount via a systemd .mount unit
                                        (ordered after network-online.target)
  unpersist <local-dir>                 Stop, disable and remove the mount unit

Examples:
  pos share nfs-client mount 100.100.100.1:/srv/media /mnt/nfs/media
  pos share nfs-client persist 100.100.100.1:/srv/media /mnt/nfs/media
  pos share nfs-client list
  pos share nfs-client unmount /mnt/nfs/media
EOF
    exit 0
}

cmd="${1:-}"
case "$cmd" in
    -h|--help) usage ;;
    mount|unmount|list|persist|unpersist) ;;
    "") err "Missing command (mount|unmount|list|persist|unpersist)" ;;
    *) err "Unknown command '$cmd' (see --help)" ;;
esac

validate_share() {
    local what="$1"
    case "$what" in
        /*) err "Invalid share '$what' — expected <server:export> (e.g. 10.0.0.5:/srv/data)" ;;
        *:*) ;;
        *) err "Invalid share '$what' — expected <server:export> (e.g. 10.0.0.5:/srv/data)" ;;
    esac
}

validate_dir() {
    local where="$1"
    case "$where" in
        /*) ;;
        *) err "Mount point must be an absolute path: $where" ;;
    esac
}

case "$cmd" in
    mount)
        what="${2:-}"
        where="${3:-}"
        [ -n "$what" ] && [ -n "$where" ] || err "Usage: pos share nfs-client mount <server:export> <local-dir>"
        validate_share "$what"
        validate_dir "$where"

        sudo mkdir -p "$where"
        sudo mount -t nfs -o rw,noatime "$what" "$where"
        log "Mounted $what at $where"
        ;;

    unmount)
        where="${2:-}"
        [ -n "$where" ] || err "Usage: pos share nfs-client unmount <local-dir>"
        validate_dir "$where"

        sudo umount "$where"
        log "Unmounted $where"
        ;;

    list)
        if findmnt -t nfs,nfs4 >/dev/null 2>&1; then
            findmnt -t nfs,nfs4
        else
            echo "No NFS mounts"
        fi
        ;;

    persist)
        what="${2:-}"
        where="${3:-}"
        [ -n "$what" ] && [ -n "$where" ] || err "Usage: pos share nfs-client persist <server:export> <local-dir>"
        validate_share "$what"
        validate_dir "$where"

        unit="$(systemd-escape --path --suffix=mount "$where")"
        unit_file="/etc/systemd/system/${unit}"

        sudo mkdir -p "$where"
        cat <<UNIT | sudo tee "$unit_file" >/dev/null
[Unit]
Description=NFS mount of ${what} at ${where}
After=network-online.target
Wants=network-online.target

[Mount]
What=${what}
Where=${where}
Type=nfs
Options=defaults,_netdev,rw,noatime
UNIT
        sudo systemctl daemon-reload
        sudo systemctl enable --now "$unit"
        log "Persistent NFS mount: ${what} → ${where} (${unit})"
        notify_send "NFS mount persisted: ${what} → ${where}"
        ;;

    unpersist)
        where="${2:-}"
        [ -n "$where" ] || err "Usage: pos share nfs-client unpersist <local-dir>"
        validate_dir "$where"

        unit="$(systemd-escape --path --suffix=mount "$where")"
        unit_file="/etc/systemd/system/${unit}"

        if [ ! -f "$unit_file" ]; then
            warn "No systemd mount unit for $where (${unit})"
            exit 0
        fi

        sudo systemctl disable "$unit" 2>/dev/null || true
        sudo systemctl stop "$unit" 2>/dev/null || true
        sudo rm -f "$unit_file"
        sudo systemctl daemon-reload
        log "Removed persistent NFS mount: $where"
        notify_send "NFS persistent mount removed: $where"
        ;;
esac