# modules/kubernetes.py — read-only cluster view via the in-cluster ServiceAccount
#
# Auth: management-platform-viewer-sa (get/list/watch on pods, services,
# deployments.apps — no secrets, no write, no exec/log), bound per-namespace
# across the 8 app namespaces below. There is no cluster-wide RoleBinding,
# so every list call below is scoped to one namespace at a time.
from datetime import datetime, timezone

try:
    from kubernetes import client, config as k8s_config
    from kubernetes.client.rest import ApiException
    _K8S_IMPORT_OK = True
except ImportError:
    _K8S_IMPORT_OK = False

NAMESPACES = [
    'n8n', 'odoo', 'mautic', 'erpnext', 'nextcloud',
    'jenkins-agents', 'jenkins', 'management-platform',
]

_core_v1 = None
_apps_v1 = None
_custom_objects = None
_networking_v1 = None
K8S_AVAILABLE = False


def _init_client():
    global _core_v1, _apps_v1, _custom_objects, _networking_v1, K8S_AVAILABLE
    if _core_v1 is not None or not _K8S_IMPORT_OK:
        return
    try:
        k8s_config.load_incluster_config()
        _core_v1 = client.CoreV1Api()
        _apps_v1 = client.AppsV1Api()
        _custom_objects = client.CustomObjectsApi()
        _networking_v1 = client.NetworkingV1Api()
        K8S_AVAILABLE = True
    except Exception as e:
        print(f"[kubernetes] in-cluster config unavailable: {e}")


# ────────────────────────────────────────────────────────────────
# HELPERS
# ────────────────────────────────────────────────────────────────

def _age_str(dt):
    if not dt:
        return '—'
    seconds = int((datetime.now(timezone.utc) - dt).total_seconds())
    if seconds < 60:
        return f'{seconds}s'
    minutes = seconds // 60
    if minutes < 60:
        return f'{minutes}m'
    hours = minutes // 60
    if hours < 24:
        return f'{hours}h {minutes % 60}m'
    days = hours // 24
    return f'{days}d {hours % 24}h'


_CRASH_REASONS = ('CrashLoopBackOff', 'ImagePullBackOff', 'ErrImagePull', 'Error')


def _pod_health(pod):
    statuses = pod.status.container_statuses or []
    for cs in statuses:
        waiting = cs.state.waiting if cs.state else None
        if waiting and waiting.reason in _CRASH_REASONS:
            return 'failed'
    phase = pod.status.phase or 'Unknown'
    if phase == 'Failed':
        return 'failed'
    if phase == 'Running':
        all_ready = all(cs.ready for cs in statuses) if statuses else True
        return 'healthy' if all_ready else 'degraded'
    return 'degraded'  # Pending, Unknown, etc.


def _ready_count(pod):
    statuses = pod.status.container_statuses or []
    ready = sum(1 for cs in statuses if cs.ready)
    return f'{ready}/{len(statuses)}'


def _restart_count(pod):
    statuses = pod.status.container_statuses or []
    return sum(cs.restart_count for cs in statuses)


def _deploy_health(desired, ready):
    if desired == 0:
        return 'degraded'
    if ready == desired:
        return 'healthy'
    if ready == 0:
        return 'failed'
    return 'degraded'


def _parse_cpu(v):
    v = (v or '0').strip()
    try:
        if v.endswith('n'):
            return int(v[:-1]) / 1_000_000
        if v.endswith('u'):
            return int(v[:-1]) / 1_000
        if v.endswith('m'):
            return int(v[:-1])
        return float(v) * 1000
    except ValueError:
        return 0


_MEM_UNITS = {'Ki': 1 / 1024, 'Mi': 1, 'Gi': 1024, 'K': 1 / 1024, 'M': 1, 'G': 1024}


def _parse_mem_mib(v):
    v = (v or '0').strip()
    for suffix, factor in _MEM_UNITS.items():
        if v.endswith(suffix):
            try:
                return float(v[:-len(suffix)]) * factor
            except ValueError:
                return 0
    try:
        return float(v) / (1024 * 1024)
    except ValueError:
        return 0


# ────────────────────────────────────────────────────────────────
# PODS / DEPLOYMENTS
# ────────────────────────────────────────────────────────────────

def list_pods():
    _init_client()
    pods = []
    if not K8S_AVAILABLE:
        return pods
    for ns in NAMESPACES:
        try:
            resp = _core_v1.list_namespaced_pod(ns)
        except ApiException as e:
            print(f"[kubernetes] list pods failed for {ns}: {e}")
            continue
        for pod in resp.items:
            pods.append({
                'name':      pod.metadata.name,
                'namespace': ns,
                'phase':     pod.status.phase or 'Unknown',
                'health':    _pod_health(pod),
                'ready':     _ready_count(pod),
                'restarts':  _restart_count(pod),
                'age':       _age_str(pod.metadata.creation_timestamp),
            })
    return pods


def list_deployments():
    _init_client()
    deployments = []
    if not K8S_AVAILABLE:
        return deployments
    for ns in NAMESPACES:
        try:
            resp = _apps_v1.list_namespaced_deployment(ns)
        except ApiException as e:
            print(f"[kubernetes] list deployments failed for {ns}: {e}")
            continue
        for dep in resp.items:
            desired = dep.spec.replicas or 0
            ready = dep.status.ready_replicas or 0
            deployments.append({
                'name':      dep.metadata.name,
                'namespace': ns,
                'ready':     ready,
                'desired':   desired,
                'health':    _deploy_health(desired, ready),
                'age':       _age_str(dep.metadata.creation_timestamp),
            })
    return deployments


def get_ingress_info(name, namespace):
    """Real domain/TLS for one Ingress, or None if unavailable/not found.
    Used by modules/sites.py instead of the old hardcoded Docker-era
    domain fields — reflects actual live k8s Ingress state."""
    _init_client()
    if not K8S_AVAILABLE:
        return None
    try:
        ing = _networking_v1.read_namespaced_ingress(name, namespace)
    except Exception:
        return None
    host = None
    if ing.spec and ing.spec.rules:
        for rule in ing.spec.rules:
            if rule.host:
                host = rule.host
                break
    tls = bool(ing.spec and ing.spec.tls)
    return {'host': host, 'tls': tls}


def list_deployments_for_namespace(ns):
    """Targeted single-namespace deployment list (vs. list_deployments()'s
    fixed NAMESPACES sweep) — used by modules/sites.py per app."""
    _init_client()
    if not K8S_AVAILABLE:
        return []
    try:
        resp = _apps_v1.list_namespaced_deployment(ns)
    except Exception as e:
        print(f"[kubernetes] list deployments failed for {ns}: {e}")
        return []
    out = []
    for dep in resp.items:
        desired = dep.spec.replicas or 0
        ready = dep.status.ready_replicas or 0
        containers = dep.spec.template.spec.containers or []
        image = containers[0].image if containers else '—'
        out.append({
            'name':    dep.metadata.name,
            'desired': desired,
            'ready':   ready,
            'health':  _deploy_health(desired, ready),
            'image':   image,
        })
    return out


def get_pod_metrics():
    """Best-effort CPU/mem per pod via metrics-server. Returns {} if it's not
    installed or unreachable — callers must treat an empty dict as 'no data',
    never as an error."""
    _init_client()
    metrics = {}
    if not K8S_AVAILABLE:
        return metrics
    for ns in NAMESPACES:
        try:
            resp = _custom_objects.list_namespaced_custom_object(
                'metrics.k8s.io', 'v1beta1', ns, 'pods'
            )
        except Exception:
            continue
        for item in resp.get('items', []):
            name = item.get('metadata', {}).get('name')
            containers = item.get('containers', [])
            cpu = sum(_parse_cpu(c.get('usage', {}).get('cpu')) for c in containers)
            mem = sum(_parse_mem_mib(c.get('usage', {}).get('memory')) for c in containers)
            metrics[f'{ns}/{name}'] = {'cpu_millicores': round(cpu), 'mem_mib': round(mem)}
    return metrics


def get_cluster_overview():
    """Single call powering the Cluster page: pods + deployments grouped by
    namespace, plus summary counts. Mirrors the shape of get_all_stats() /
    get_sites_list() in the docker-facing modules."""
    pods = list_pods()
    deployments = list_deployments()
    metrics = get_pod_metrics()

    for pod in pods:
        key = f"{pod['namespace']}/{pod['name']}"
        if key in metrics:
            pod['metrics'] = metrics[key]

    by_namespace = {ns: {'pods': [], 'deployments': []} for ns in NAMESPACES}
    for pod in pods:
        by_namespace[pod['namespace']]['pods'].append(pod)
    for dep in deployments:
        by_namespace[dep['namespace']]['deployments'].append(dep)

    summary = {
        'total_pods':          len(pods),
        'healthy':             sum(1 for p in pods if p['health'] == 'healthy'),
        'degraded':            sum(1 for p in pods if p['health'] == 'degraded'),
        'failed':              sum(1 for p in pods if p['health'] == 'failed'),
        'total_deployments':   len(deployments),
        'deployments_healthy': sum(1 for d in deployments if d['health'] == 'healthy'),
    }

    return {
        'available':        K8S_AVAILABLE,
        'namespaces':        by_namespace,
        'summary':           summary,
        'metrics_available': bool(metrics),
    }