#!/usr/bin/env bash
# Outputs per-pod CPU/MEM metrics and namespace quota as JSON.
# Usage: k8s-metrics.sh <namespace>
set -euo pipefail

NS="${1:-tenant-5}"

# ── Unit normalization ───────────────────────────────────────────────────────

# Normalize CPU string to millicores integer
normalize_cpu() {
    local val="$1"
    if [[ "$val" =~ ^([0-9]+)m$ ]]; then
        echo "${BASH_REMATCH[1]}"
    elif [[ "$val" =~ ^([0-9]+(\.[0-9]+)?)$ ]]; then
        awk "BEGIN { printf \"%d\", ${BASH_REMATCH[1]} * 1000 }"
    else
        echo 0
    fi
}

# Normalize memory string to MiB integer
normalize_mem() {
    local val="$1"
    if [[ "$val" =~ ^([0-9]+)Gi$ ]]; then
        echo $(( ${BASH_REMATCH[1]} * 1024 ))
    elif [[ "$val" =~ ^([0-9]+)Mi$ ]]; then
        echo "${BASH_REMATCH[1]}"
    elif [[ "$val" =~ ^([0-9]+)Ki$ ]]; then
        echo $(( ${BASH_REMATCH[1]} / 1024 ))
    elif [[ "$val" =~ ^([0-9]+)$ ]]; then
        echo $(( ${BASH_REMATCH[1]} / 1048576 ))
    else
        echo 0
    fi
}

# Format millicores for display (always "Xm")
fmt_cpu() {
    local m="$1"
    echo "${m}m"
}

# Format MiB for display ("343Mi" or "1.50Gi")
fmt_mem() {
    local mib="$1"
    if [[ $mib -lt 1024 ]]; then
        echo "${mib}Mi"
    else
        awk "BEGIN { printf \"%.2fGi\", $mib / 1024 }"
    fi
}

# ── Fetch data ───────────────────────────────────────────────────────────────

pods_json=$(kubectl get pods -n "$NS" -o json 2>/dev/null)         || exit 1
top_output=$(kubectl top pods -n "$NS" --no-headers 2>/dev/null)   || top_output=""
quota_json=$(kubectl get resourcequota -n "$NS" -o json 2>/dev/null) || quota_json='{"items":[]}'

# ── Build podName → app map ──────────────────────────────────────────────────

declare -A name_to_app
while IFS= read -r line; do
    pod_name=$(echo "$line" | jq -r '.name')
    app=$(echo "$line" | jq -r '.app')
    name_to_app["$pod_name"]="$app"
done < <(echo "$pods_json" | jq -c '.items[] | {name: .metadata.name, app: (.metadata.labels["app.kubernetes.io/instance"] // .metadata.name)}')

# ── Parse kubectl top ────────────────────────────────────────────────────────

declare -A top_cpu  # app → cpuM
declare -A top_mem  # app → memMi
cpu_actual=0
mem_actual=0

while IFS= read -r line; do
    [[ -z "$line" ]] && continue
    read -r pod_name cpu_str mem_str <<< "$line"
    app="${name_to_app[$pod_name]:-}"
    [[ -z "$app" ]] && continue
    cpu_m=$(normalize_cpu "$cpu_str")
    mem_mib=$(normalize_mem "$mem_str")
    top_cpu["$app"]=$(( ${top_cpu[$app]:-0} + cpu_m ))
    top_mem["$app"]=$(( ${top_mem[$app]:-0} + mem_mib ))
    cpu_actual=$(( cpu_actual + cpu_m ))
    mem_actual=$(( mem_actual + mem_mib ))
done <<< "$top_output"

# ── Build podMetrics JSON array ──────────────────────────────────────────────

pod_metrics="["
first=1
while IFS= read -r line; do
    app=$(echo "$line" | jq -r '.app')
    cpu_m="${top_cpu[$app]:-"-1"}"
    mem_mib="${top_mem[$app]:-"-1"}"
    [[ $first -eq 0 ]] && pod_metrics+=","
    pod_metrics+=$(jq -nc --arg app "$app" --argjson cpu "$cpu_m" --argjson mem "$mem_mib" \
        '{app: $app, cpuM: $cpu, memMi: $mem}')
    first=0
done < <(echo "$pods_json" | jq -c '[.items[] | {app: (.metadata.labels["app.kubernetes.io/instance"] // .metadata.name)}] | unique_by(.app)[]')
pod_metrics+="]"

# ── Parse resourcequota ──────────────────────────────────────────────────────

q_cpu_req_used=$(echo "$quota_json" | jq -r '.items[0].status.used["requests.cpu"]  // "0"')
q_cpu_req_hard=$(echo "$quota_json" | jq -r '.items[0].status.hard["requests.cpu"]  // "0"')
q_cpu_lim_used=$(echo "$quota_json" | jq -r '.items[0].status.used["limits.cpu"]    // "0"')
q_cpu_lim_hard=$(echo "$quota_json" | jq -r '.items[0].status.hard["limits.cpu"]    // "0"')
q_mem_req_used=$(echo "$quota_json" | jq -r '.items[0].status.used["requests.memory"] // "0"')
q_mem_req_hard=$(echo "$quota_json" | jq -r '.items[0].status.hard["requests.memory"] // "0"')
q_mem_lim_used=$(echo "$quota_json" | jq -r '.items[0].status.used["limits.memory"]   // "0"')
q_mem_lim_hard=$(echo "$quota_json" | jq -r '.items[0].status.hard["limits.memory"]   // "0"')

cpu_req_used_m=$(normalize_cpu "$q_cpu_req_used")
cpu_req_hard_m=$(normalize_cpu "$q_cpu_req_hard")
cpu_lim_used_m=$(normalize_cpu "$q_cpu_lim_used")
cpu_lim_hard_m=$(normalize_cpu "$q_cpu_lim_hard")
mem_req_used_mib=$(normalize_mem "$q_mem_req_used")
mem_req_hard_mib=$(normalize_mem "$q_mem_req_hard")
mem_lim_used_mib=$(normalize_mem "$q_mem_lim_used")
mem_lim_hard_mib=$(normalize_mem "$q_mem_lim_hard")

cpu_req_pct=$(awk "BEGIN { printf \"%.4f\", $cpu_req_used_m / ($cpu_req_hard_m > 0 ? $cpu_req_hard_m : 1) }")
cpu_lim_pct=$(awk "BEGIN { printf \"%.4f\", $cpu_lim_used_m / ($cpu_lim_hard_m > 0 ? $cpu_lim_hard_m : 1) }")
mem_req_pct=$(awk "BEGIN { printf \"%.4f\", $mem_req_used_mib / ($mem_req_hard_mib > 0 ? $mem_req_hard_mib : 1) }")
mem_lim_pct=$(awk "BEGIN { printf \"%.4f\", $mem_lim_used_mib / ($mem_lim_hard_mib > 0 ? $mem_lim_hard_mib : 1) }")

cpu_req_label="$(fmt_cpu $cpu_req_used_m) / $(fmt_cpu $cpu_req_hard_m)"
cpu_lim_label="$(fmt_cpu $cpu_lim_used_m) / $(fmt_cpu $cpu_lim_hard_m)"
mem_req_label="$(fmt_mem $mem_req_used_mib) / $(fmt_mem $mem_req_hard_mib)"
mem_lim_label="$(fmt_mem $mem_lim_used_mib) / $(fmt_mem $mem_lim_hard_mib)"

# ── Output ───────────────────────────────────────────────────────────────────

jq -nc \
    --argjson podMetrics "$pod_metrics" \
    --argjson cpuActualM  "$cpu_actual" \
    --argjson memActualMi "$mem_actual" \
    --argjson cpuReqPct   "$cpu_req_pct" \
    --argjson cpuLimPct   "$cpu_lim_pct" \
    --argjson memReqPct   "$mem_req_pct" \
    --argjson memLimPct   "$mem_lim_pct" \
    --arg     cpuReqLabel "$cpu_req_label" \
    --arg     cpuLimLabel "$cpu_lim_label" \
    --arg     memReqLabel "$mem_req_label" \
    --arg     memLimLabel "$mem_lim_label" \
    '{
        podMetrics: $podMetrics,
        quota: {
            cpuActualM:  $cpuActualM,
            memActualMi: $memActualMi,
            cpuReqPct:   $cpuReqPct,
            cpuLimPct:   $cpuLimPct,
            memReqPct:   $memReqPct,
            memLimPct:   $memLimPct,
            cpuReqLabel: $cpuReqLabel,
            cpuLimLabel: $cpuLimLabel,
            memReqLabel: $memReqLabel,
            memLimLabel: $memLimLabel
        }
    }'