#!/usr/bin/env bash
# uptime-watcher.sh — simple hatch-hook watcher: spawn/rebuild from spec.
#
# Register as a hatch hook (id `uptime-watcher`, poll 120s, timeout 300s)
# alongside tunnel-keeper. Each poll it guarantees the three things a
# container rebuild destroys:
#   1. provisioning  — runs recover-after-rebuild.sh on a fresh root fs
#   2. supervisor    — respawns gcp-tunnel-up.sh if it died
#   3. cron jobs     — reinstalls crontab from ~/workspace/cron/*.persist
#
# It also verifies the VM-side SSH forward answers a banner, and wakes the
# operator (rate-limited, 30 min) only when something stays broken across
# polls. Silent on success. Safe to run by hand or from cron too.
set -u

# --- runtime (hatch hook functions, or local fallbacks) ---
if [ -n "${HATCH_HOOK_RUNTIME:-}" ] && [ -f "$HATCH_HOOK_RUNTIME" ]; then
    # shellcheck disable=SC1090
    source "$HATCH_HOOK_RUNTIME"
else
    log() { echo "[uptime-watcher] $1 $2"; }
    silent() { echo "[uptime-watcher] silent: $1 $2"; }
    wake() { echo "[uptime-watcher] WAKE $1 $2"; }
fi

# --- identity (per-machine, persistent) ---
ENV_FILE="$HOME/workspace/tunnel/machine.env"
# shellcheck disable=SC1090
[ -f "$ENV_FILE" ] && . "$ENV_FILE"
MACHINE="${MUSE_MACHINE:-unknown}"
SSH_PORT="${SSH_PORT:-0}"
TERM_PORT="${TERM_PORT:-0}"

STATE_DIR="$HOME/hooks/state/uptime-watcher"
BIN="$HOME/workspace/bin"
RECOVER="$BIN/recover-after-rebuild.sh"
SUPERVISOR="$BIN/gcp-tunnel-up.sh"
CRON_RESTORE="$BIN/persistent-crontab.sh"
SSH_KEY="$HOME/.ssh/vm_to_gcp"
GCP_HOST="${FD_VM_HOST:-34.139.37.135}"
GCP_USER="${FD_VM_USER:-super}"
FAIL_COUNT="$STATE_DIR/consec_failures"
LAST_WAKE="$STATE_DIR/last_wake_ts"

mkdir -p "$STATE_DIR"
exec 9>"$STATE_DIR/watcher.lock"
flock -n 9 || { silent "previous poll still running" '{}'; exit 0; }
read_int() { [ -f "$1" ] && tr -cd '0-9' < "$1" || echo 0; }

actions=""
fail=""

# --- 1. fresh rebuild? provision ---
if [ ! -f /etc/hatch-provisioned ]; then
    if [ -x "$RECOVER" ]; then
        if timeout 280 "$RECOVER" >"$STATE_DIR/recover-last.log" 2>&1; then
            actions="${actions}provisioned "
            log "recovery" '{"event":"provisioned_after_rebuild"}'
        else
            fail="recover_failed"
        fi
    else
        fail="recover_missing"
    fi
fi

# --- 2. supervisor alive? respawn ---
if [ -z "$fail" ] && ! pgrep -f "workspace/bin/gcp-tunnel-up\.sh$" >/dev/null; then
    if [ -x "$SUPERVISOR" ] && [ -f "$SSH_KEY" ]; then
        setsid nohup "$SUPERVISOR" >/dev/null 2>&1 < /dev/null 9>&- &
        disown 2>/dev/null || true
        actions="${actions}supervisor-respawned "
        log "supervisor" '{"event":"respawned"}'
    else
        fail="supervisor_unstartable"
    fi
fi

# --- 3. cron jobs alive? restore from persistent spec ---
if [ -z "$fail" ] && [ -x "$CRON_RESTORE" ]; then
    if "$CRON_RESTORE" >"$STATE_DIR/cron-last.log" 2>&1; then
        grep -q "reinstalled" "$STATE_DIR/cron-last.log" \
            && actions="${actions}cron-restored "
    else
        fail="cron_restore_failed"
    fi
fi

# --- 4. VM forward answers? (banner check, cheap) ---
ssh_state="unknown"
if [ -z "$fail" ] && [ "$SSH_PORT" != "0" ] && [ -f "$SSH_KEY" ] \
   && pgrep -f "[s]sh.*${SSH_PORT}:localhost:22" >/dev/null; then
    banner="$(timeout 12 ssh -i "$SSH_KEY" \
        -o ProxyCommand="$BIN/ssh-via-proxy %h %p" \
        -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null \
        -o ConnectTimeout=8 -o BatchMode=yes \
        "$GCP_USER@$GCP_HOST" \
        "timeout 5 bash -c 'exec 3<>/dev/tcp/127.0.0.1/$SSH_PORT && head -c 4 <&3' 2>/dev/null" \
        2>/dev/null || true)"
    case "$banner" in
        SSH-*) ssh_state="up" ;;
        *) ssh_state="stale-forward"; fail="forward_dead" ;;
    esac
elif [ -z "$fail" ]; then
    ssh_state="down"
    fail="tunnel_down"
fi

payload="$(printf '{"machine":"%s","ssh":"%s","actions":"%s"}' \
    "$MACHINE" "$ssh_state" "${actions:-none}")"

# --- 5. silent ok, or rate-limited wake on persistent failure ---
if [ -z "$fail" ]; then
    printf 0 > "$FAIL_COUNT"
    silent "uptime watcher poll ok" "$payload"
    exit 0
fi

count=$(( $(read_int "$FAIL_COUNT") + 1 ))
printf '%s' "$count" > "$FAIL_COUNT"
log "failure" "{\"condition\":\"$fail\",\"consec\":\"$count\"}"
if [ "$count" -ge 2 ]; then
    now=$(date +%s); last=$(read_int "$LAST_WAKE")
    if [ $(( now - last )) -ge 1800 ]; then
        printf '%s' "$now" > "$LAST_WAKE"
        wake "$fail" "$payload"
        exit 0
    fi
fi
silent "failure $fail ($count) — below wake threshold" "$payload"