#!/usr/bin/env bash
set -euo pipefail

RCLONE_CONF="${HOME}/.config/rclone/rclone.conf"
SSH_DIR="${HOME}/.ssh"
REGISTRY="${HOME}/.config/tinyboard/spokes"

RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
CYAN='\033[0;36m'
NC='\033[0m'

info()   { echo -e "${GREEN}[+]${NC} $*"; }
warn()   { echo -e "${YELLOW}[!]${NC} $*"; }
die()    { echo -e "${RED}[ERROR]${NC} $*" >&2; exit 1; }
header() { echo -e "\n${CYAN}══════════════════════════════════════════${NC}"; echo -e "${CYAN}  $*${NC}"; echo -e "${CYAN}══════════════════════════════════════════${NC}"; }

check_deps() {
    local missing=()
    for cmd in "$@"; do
        if ! command -v "$cmd" >/dev/null 2>&1; then
            missing+=("$cmd")
        fi
    done
    if [ ${#missing[@]} -gt 0 ]; then
        die "Missing required dependencies: ${missing[*]}"
    fi
}

retry_or_abort() {
    local test_cmd="$1"
    local fail_msg="$2"
    while true; do
        if eval "$test_cmd" 2>/dev/null; then
            return 0
        fi
        echo ""
        warn "$fail_msg"
        echo -e "  ${YELLOW}[R]${NC} Retry   ${RED}[A]${NC} Abort"
        read -rp "Choice: " CHOICE
        case "${CHOICE,,}" in
            r) info "Retrying..." ;;
            a) die "Aborted." ;;
            *) warn "Press R to retry or A to abort." ;;
        esac
    done
}

if [ "$(id -u)" -eq 0 ]; then
    die "Running as root — keys will be written to /root/.ssh. Run as the hub user instead."
fi
mkdir -p "$SSH_DIR"
touch "$SSH_DIR/known_hosts"
chmod 700 "$SSH_DIR"
chmod 600 "$SSH_DIR/known_hosts"

check_deps ssh ssh-keygen ssh-keyscan ssh-copy-id rclone

header "TinyBoard Hub — Onboard New Spoke"

read -rp "Spoke local user [armbian]: " SPOKE_USER
SPOKE_USER="${SPOKE_USER:-armbian}"

read -rp "Spoke name (e.g. rocky): " SPOKE_NAME
[ -n "$SPOKE_NAME" ] || die "Spoke name cannot be empty"

read -rp "Tunnel port for $SPOKE_NAME: " TUNNEL_PORT
[[ "$TUNNEL_PORT" =~ ^[0-9]+$ ]] || die "Invalid port"

KEY_NAME="${SPOKE_USER}-${SPOKE_NAME}-$(date +%Y%m)"
KEY_PATH="$SSH_DIR/$KEY_NAME"

mkdir -p "$(dirname "$RCLONE_CONF")"

header "Checking Tunnel"
info "Verifying spoke SSH service is reachable on port $TUNNEL_PORT..."
if ! timeout 5 bash -c "cat < /dev/null > /dev/tcp/localhost/$TUNNEL_PORT" 2>/dev/null; then
    die "Cannot connect to port $TUNNEL_PORT on localhost — is the tunnel up?"
fi
info "Scanning spoke host key..."
KEYSCAN=$(ssh-keyscan -p "$TUNNEL_PORT" -H localhost 2>/dev/null)
[ -n "$KEYSCAN" ] || die "Spoke not reachable on port $TUNNEL_PORT — is the tunnel up?"
while IFS= read -r KEYSCAN_LINE; do
    KEYSCAN_KEY=$(echo "$KEYSCAN_LINE" | awk '{print $2, $3}')
    if ! grep -qF "$KEYSCAN_KEY" "$SSH_DIR/known_hosts" 2>/dev/null; then
        echo "$KEYSCAN_LINE" >> "$SSH_DIR/known_hosts"
    fi
done <<< "$KEYSCAN"

header "Generating Hub-to-Spoke Access Key"
if [ -f "$KEY_PATH" ]; then
    warn "Key $KEY_PATH already exists, skipping generation."
else
    ssh-keygen -t ed25519 -f "$KEY_PATH" -N "" -C "$KEY_NAME"
    info "Key generated: $KEY_PATH"
fi
chmod 600 "$KEY_PATH"
info "Permissions set: $KEY_PATH is 600"

header "Installing Hub-to-Spoke Access Key on Spoke"
info "Copying hub public key to spoke's authorized_keys so the hub can SSH in for rclone..."
info "(You will be prompted for the $SPOKE_USER password on the spoke)"
if ssh-copy-id -i "$KEY_PATH.pub" -p "$TUNNEL_PORT" "$SPOKE_USER"@localhost; then
    info "Key copied."
else
    warn "ssh-copy-id failed — password auth may be disabled on the spoke."
    warn "Manually append the hub public key to the spoke's authorized_keys:"
    echo ""
    echo "  cat $KEY_PATH.pub"
    echo "  Then on the spoke, append the output to:"
    echo "  /home/$SPOKE_USER/.ssh/authorized_keys"
    echo ""
    read -rp "Press ENTER once the key has been added to the spoke..."
fi

header "Testing Hub-to-Spoke Key Auth"
retry_or_abort \
    "ssh -i \"$KEY_PATH\" -o BatchMode=yes -o ConnectTimeout=10 -p \"$TUNNEL_PORT\" \"$SPOKE_USER\"@localhost exit" \
    "Key auth failed. Check authorized_keys on the spoke."
info "Key auth to spoke successful."

header "Adding rclone Remote"
if grep -q "\[${SPOKE_NAME}-remote\]" "$RCLONE_CONF" 2>/dev/null; then
    warn "Remote [${SPOKE_NAME}-remote] already exists in $RCLONE_CONF, skipping."
else
    [ -s "$RCLONE_CONF" ] && tail -c1 "$RCLONE_CONF" | grep -qv $'\n' && echo "" >> "$RCLONE_CONF"
    python3 - "$RCLONE_CONF" "$SPOKE_NAME" "$TUNNEL_PORT" "$KEY_PATH" <<'PYEOF'
import sys
path, name, port, key = sys.argv[1], sys.argv[2], sys.argv[3], sys.argv[4]
with open(path, 'a') as f:
    f.write(f"\n[{name}-remote]\ntype = sftp\nhost = localhost\nport = {port}\nkey_file = {key}\nshell_type = unix\nmd5sum_command = md5sum\nsha1sum_command = sha1sum\n")
PYEOF
    info "Remote [${SPOKE_NAME}-remote] added to $RCLONE_CONF."
fi

header "Union Remote (optional)"
read -rp "Add this spoke to a union remote for redundancy? [y/N]: " ADD_UNION
ADD_UNION="${ADD_UNION:-n}"
if [[ "${ADD_UNION,,}" == "y" ]]; then
    read -rp "Union remote name [shared-union]: " UNION_NAME
    UNION_NAME="${UNION_NAME:-shared-union}"
    read -rp "Subfolder path on the spoke being onboarded (e.g. books, leave blank for root): " UNION_PATH
    echo ""
    echo "Upstream access mode for this spoke:"
    echo "  0) None       - full read/write (default)"
    echo "  1) :ro        - read only"
    echo "  2) :nc        - no create (read/write existing, no new files)"
    echo "  3) :writeback - writeback cache"
    echo ""
    read -rp "Choose [0-3]: " UNION_MODE
    UNION_MODE="${UNION_MODE:-0}"
    case "$UNION_MODE" in
        0) UPSTREAM_TAG="" ;;
        1) UPSTREAM_TAG=":ro" ;;
        2) UPSTREAM_TAG=":nc" ;;
        3) UPSTREAM_TAG=":writeback" ;;
        *) warn "Invalid choice, defaulting to full read/write."; UPSTREAM_TAG="" ;;
    esac
    if [ -n "$UNION_PATH" ]; then
        UPSTREAM="${SPOKE_NAME}-remote:${UNION_PATH}${UPSTREAM_TAG}"
    else
        UPSTREAM="${SPOKE_NAME}-remote:${UPSTREAM_TAG}"
    fi
    if grep -q "^\[${UNION_NAME}\]" "$RCLONE_CONF" 2>/dev/null; then
        ALREADY=$(python3 - "$RCLONE_CONF" "$UNION_NAME" "${SPOKE_NAME}-remote:" <<'PYEOF2'
import sys
path, section, prefix = sys.argv[1], sys.argv[2], sys.argv[3]
with open(path) as f:
    lines = f.readlines()
in_section = False
for line in lines:
    if line.strip() == f"[{section}]":
        in_section = True
    elif line.strip().startswith("["):
        in_section = False
    if in_section and line.startswith("upstreams =") and prefix in line:
        print("yes")
        sys.exit(0)
print("no")
PYEOF2
)
        if [ "$ALREADY" = "yes" ]; then
            warn "Upstream for ${SPOKE_NAME}-remote already in union remote [${UNION_NAME}], skipping."
        else
            python3 - "$RCLONE_CONF" "$UNION_NAME" "$UPSTREAM" <<'PYEOF2'
import sys
path, section, upstream = sys.argv[1], sys.argv[2], sys.argv[3]
with open(path) as f:
    lines = f.readlines()
out = []
in_section = False
for line in lines:
    if line.strip() == f"[{section}]":
        in_section = True
    elif line.strip().startswith("["):
        in_section = False
    if in_section and line.startswith("upstreams ="):
        line = line.rstrip() + " " + upstream + "\n"
    out.append(line)
with open(path, "w") as f:
    f.writelines(out)
PYEOF2
            info "Added '$UPSTREAM' to union remote [${UNION_NAME}]."
        fi
    else
        [ -s "$RCLONE_CONF" ] && tail -c1 "$RCLONE_CONF" | grep -qv $'\n' && echo "" >> "$RCLONE_CONF"
        printf '\n[%s]\ntype = union\nupstreams = %s\n' "$UNION_NAME" "$UPSTREAM" >> "$RCLONE_CONF"
        info "Union remote [${UNION_NAME}] created with upstream '$UPSTREAM'."
    fi
fi

header "Testing rclone Connection"
if rclone lsd "${SPOKE_NAME}-remote:" --config "$RCLONE_CONF" 2>/dev/null; then
    info "rclone connection to $SPOKE_NAME successful."
else
    warn "rclone test failed. Check the remote config in $RCLONE_CONF."
fi

header "Registering Spoke"
mkdir -p "$(dirname "$REGISTRY")"
MOUNT_POINT="${HOME}/mnt/${SPOKE_NAME}"
mkdir -p "$MOUNT_POINT"
if grep -q "^${SPOKE_NAME} " "$REGISTRY" 2>/dev/null; then
    warn "$SPOKE_NAME already in registry, updating."
    grep -v "^${SPOKE_NAME} " "$REGISTRY" > "${REGISTRY}.tmp" 2>/dev/null || true
    mv "${REGISTRY}.tmp" "$REGISTRY"
fi
echo "${SPOKE_NAME} ${TUNNEL_PORT} ${KEY_PATH} ${MOUNT_POINT}" >> "$REGISTRY"
info "$SPOKE_NAME registered."

header "Setting Up Auto-Mount"
MOUNT_CMD="rclone mount ${SPOKE_NAME}-remote: ${MOUNT_POINT} --config ${HOME}/.config/rclone/rclone.conf --vfs-cache-mode writes --allow-other --allow-non-empty --daemon"
CRON_ENTRY="@reboot ${MOUNT_CMD}"
EXISTING=$(crontab -l 2>/dev/null || true)
if echo "$EXISTING" | grep -qF "${SPOKE_NAME}-remote:"; then
    warn "Crontab entry for ${SPOKE_NAME}-remote already exists, skipping."
else
    CRONTAB_BACKUP="${HOME}/.config/tinyboard/crontab.$(date +%Y%m%d%H%M%S)"
    mkdir -p "$(dirname "$CRONTAB_BACKUP")"
    echo "$EXISTING" > "$CRONTAB_BACKUP"
    info "Crontab backed up to $CRONTAB_BACKUP"
    { echo "$EXISTING"; echo "$CRON_ENTRY"; } | crontab -
    info "Auto-mount crontab entry added for ${SPOKE_NAME}."
fi
info "Starting mount now..."
mkdir -p "$MOUNT_POINT"
eval "$MOUNT_CMD" 2>/dev/null && info "Mounted ${SPOKE_NAME} at ${MOUNT_POINT}." || warn "Mount failed — will retry on next reboot."

header "Onboarding Complete"
echo -e "  Spoke:       ${GREEN}$SPOKE_NAME${NC}"
echo -e "  Port:        ${GREEN}$TUNNEL_PORT${NC}"
echo -e "  Hub key:     ${GREEN}$KEY_PATH${NC}"
echo -e "  rclone:      ${GREEN}${SPOKE_NAME}-remote${NC}"
echo ""