#!/usr/bin/env bash
#
# Phase 4 Validation: Observability Stack
#
# Validates that RFC 0042 components are deployed and healthy:
# - Prometheus (targets UP)
# - Grafana (SSO working, datasources configured)
# - Loki (logs visible)
# - Alertmanager (cluster formed)
#
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m'

PASSED=0
FAILED=0
WARNINGS=0

log_info() {
    echo -e "${BLUE}[INFO]${NC} $1"
}

log_pass() {
    echo -e "${GREEN}[PASS]${NC} $1"
    ((PASSED++))
}

log_fail() {
    echo -e "${RED}[FAIL]${NC} $1"
    ((FAILED++))
}

log_warn() {
    echo -e "${YELLOW}[WARN]${NC} $1"
    ((WARNINGS++))
}

check_prometheus() {
    log_info "Checking Prometheus..."

    # Check if namespace exists
    if ! kubectl get namespace observability &> /dev/null; then
        log_fail "observability namespace does not exist"
        return
    fi

    # Check pod health
    local ready_pods
    ready_pods=$(kubectl -n observability get pods -l app=prometheus -o json 2>/dev/null | jq '[.items[] | select(.status.phase == "Running") | select(.status.containerStatuses[]?.ready == true)] | length')

    if [ "$ready_pods" -ge 1 ]; then
        log_pass "Prometheus has $ready_pods ready pods"
    else
        log_fail "Prometheus has no ready pods"
        return
    fi

    # Check Prometheus targets via API
    local prom_pod
    prom_pod=$(kubectl -n observability get pods -l app=prometheus -o jsonpath='{.items[0].metadata.name}' 2>/dev/null || echo "")

    if [ -n "$prom_pod" ]; then
        local targets
        targets=$(kubectl -n observability exec "$prom_pod" -- wget -q -O - http://localhost:9090/api/v1/targets 2>/dev/null || echo '{}')

        local active_targets
        active_targets=$(echo "$targets" | jq '.data.activeTargets | length' 2>/dev/null || echo "0")

        local up_targets
        up_targets=$(echo "$targets" | jq '[.data.activeTargets[] | select(.health == "up")] | length' 2>/dev/null || echo "0")

        if [ "$active_targets" -gt 0 ]; then
            log_pass "Prometheus has $active_targets active targets ($up_targets UP)"
        else
            log_warn "No active Prometheus targets found"
        fi

        # Check for down targets
        local down_targets
        down_targets=$(echo "$targets" | jq '[.data.activeTargets[] | select(.health == "down")] | length' 2>/dev/null || echo "0")

        if [ "$down_targets" -gt 0 ]; then
            log_warn "$down_targets Prometheus targets are DOWN"
        fi
    fi
}

check_grafana() {
    log_info "Checking Grafana..."

    # Check pod health
    local ready_pods
    ready_pods=$(kubectl -n observability get pods -l app=grafana -o json 2>/dev/null | jq '[.items[] | select(.status.phase == "Running") | select(.status.containerStatuses[]?.ready == true)] | length')

    if [ "$ready_pods" -ge 1 ]; then
        log_pass "Grafana has $ready_pods ready pods"
    else
        log_fail "Grafana has no ready pods"
        return
    fi

    # Check Grafana service
    local svc_exists
    svc_exists=$(kubectl -n observability get svc grafana -o name 2>/dev/null || echo "")

    if [ -n "$svc_exists" ]; then
        log_pass "Grafana service exists"
    else
        log_fail "Grafana service does not exist"
    fi

    # Check datasources ConfigMap
    local datasources_cm
    datasources_cm=$(kubectl -n observability get configmap grafana-datasources -o name 2>/dev/null || echo "")

    if [ -n "$datasources_cm" ]; then
        log_pass "Grafana datasources ConfigMap exists"
    else
        log_warn "Grafana datasources ConfigMap not found"
    fi

    # Check dashboards ConfigMaps
    local dashboard_cms
    dashboard_cms=$(kubectl -n observability get configmap -l grafana_dashboard=1 -o name 2>/dev/null | wc -l | tr -d ' ')

    if [ "$dashboard_cms" -gt 0 ]; then
        log_pass "Found $dashboard_cms Grafana dashboard ConfigMaps"
    else
        log_warn "No Grafana dashboard ConfigMaps found"
    fi

    # Check ingress
    local ingress_exists
    ingress_exists=$(kubectl get ingress -A -o json 2>/dev/null | jq '[.items[] | select(.spec.rules[]?.host | contains("grafana"))] | length')

    if [ "$ingress_exists" -ge 1 ]; then
        log_pass "Grafana ingress configured"
    else
        log_warn "No Grafana ingress found"
    fi
}

check_loki() {
    log_info "Checking Loki..."

    # Check pod health
    local ready_pods
    ready_pods=$(kubectl -n observability get pods -l app=loki -o json 2>/dev/null | jq '[.items[] | select(.status.phase == "Running") | select(.status.containerStatuses[]?.ready == true)] | length')

    if [ "$ready_pods" -ge 1 ]; then
        log_pass "Loki has $ready_pods ready pods"
    else
        log_fail "Loki has no ready pods"
        return
    fi

    # Check Loki service
    local svc_exists
    svc_exists=$(kubectl -n observability get svc loki -o name 2>/dev/null || echo "")

    if [ -n "$svc_exists" ]; then
        log_pass "Loki service exists"
    else
        log_fail "Loki service does not exist"
    fi

    # Check Loki health
    local loki_pod
    loki_pod=$(kubectl -n observability get pods -l app=loki -o jsonpath='{.items[0].metadata.name}' 2>/dev/null || echo "")

    if [ -n "$loki_pod" ]; then
        local loki_ready
        loki_ready=$(kubectl -n observability exec "$loki_pod" -- wget -q -O - http://localhost:3100/ready 2>/dev/null || echo "")

        if [ "$loki_ready" = "ready" ]; then
            log_pass "Loki is ready"
        else
            log_warn "Loki readiness check returned: $loki_ready"
        fi
    fi
}

check_alertmanager() {
    log_info "Checking Alertmanager..."

    # Check pod health
    local ready_pods
    ready_pods=$(kubectl -n observability get pods -l app=alertmanager -o json 2>/dev/null | jq '[.items[] | select(.status.phase == "Running") | select(.status.containerStatuses[]?.ready == true)] | length')

    if [ "$ready_pods" -ge 1 ]; then
        log_pass "Alertmanager has $ready_pods ready pods"
    else
        log_fail "Alertmanager has no ready pods"
        return
    fi

    # Check Alertmanager cluster status
    local am_pod
    am_pod=$(kubectl -n observability get pods -l app=alertmanager -o jsonpath='{.items[0].metadata.name}' 2>/dev/null || echo "")

    if [ -n "$am_pod" ]; then
        local cluster_status
        cluster_status=$(kubectl -n observability exec "$am_pod" -- wget -q -O - http://localhost:9093/api/v2/status 2>/dev/null || echo '{}')

        local cluster_peers
        cluster_peers=$(echo "$cluster_status" | jq '.cluster.peers | length' 2>/dev/null || echo "0")

        if [ "$cluster_peers" -ge 1 ]; then
            log_pass "Alertmanager cluster formed ($cluster_peers peers)"
        else
            log_warn "Alertmanager cluster not formed"
        fi
    fi

    # Check for active alerts
    if [ -n "$am_pod" ]; then
        local active_alerts
        active_alerts=$(kubectl -n observability exec "$am_pod" -- wget -q -O - http://localhost:9093/api/v2/alerts 2>/dev/null | jq 'length' 2>/dev/null || echo "0")

        if [ "$active_alerts" -gt 0 ]; then
            log_warn "$active_alerts active alerts in Alertmanager"
        else
            log_pass "No active alerts"
        fi
    fi
}

check_promtail() {
    log_info "Checking Promtail (log shipper)..."

    # Check DaemonSet
    local promtail_ds
    promtail_ds=$(kubectl -n observability get daemonset promtail -o json 2>/dev/null || echo '{}')

    local desired
    desired=$(echo "$promtail_ds" | jq '.status.desiredNumberScheduled // 0')

    local ready
    ready=$(echo "$promtail_ds" | jq '.status.numberReady // 0')

    if [ "$desired" -eq 0 ]; then
        log_warn "Promtail DaemonSet not found (may use different log collector)"
    elif [ "$ready" -eq "$desired" ]; then
        log_pass "Promtail DaemonSet healthy ($ready/$desired ready)"
    else
        log_warn "Promtail DaemonSet partially ready ($ready/$desired)"
    fi
}

print_summary() {
    echo ""
    echo "========================================"
    echo "Phase 4 Validation Summary"
    echo "========================================"
    echo -e "  ${GREEN}Passed:${NC}   $PASSED"
    echo -e "  ${RED}Failed:${NC}   $FAILED"
    echo -e "  ${YELLOW}Warnings:${NC} $WARNINGS"
    echo "========================================"

    if [ "$FAILED" -gt 0 ]; then
        echo ""
        echo -e "${RED}Phase 4 validation FAILED${NC}"
        echo "Please fix the issues above before proceeding to Phase 5."
        exit 1
    elif [ "$WARNINGS" -gt 0 ]; then
        echo ""
        echo -e "${YELLOW}Phase 4 validation passed with warnings${NC}"
        echo "Review warnings above. You may proceed to Phase 5."
        exit 0
    else
        echo ""
        echo -e "${GREEN}Phase 4 validation PASSED${NC}"
        echo "You may proceed to Phase 5 (optional)."
        exit 0
    fi
}

main() {
    echo "========================================"
    echo "Phase 4 Validation: Observability Stack"
    echo "========================================"
    echo ""

    check_prometheus
    check_grafana
    check_loki
    check_alertmanager
    check_promtail

    print_summary
}

main "$@"