--
-- Licensed to the Apache Software Foundation (ASF) under one or more
-- contributor license agreements.  See the NOTICE file distributed with
-- this work for additional information regarding copyright ownership.
-- The ASF licenses this file to You under the Apache License, Version 2.0
-- (the "License"); you may not use this file except in compliance with
-- the License.  You may obtain a copy of the License at
--
--     http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--
local base_prometheus = require("prometheus")
local tonumber        = tonumber
local core      = require("apisix.core")
local plugin    = require("apisix.plugin")
local control   = require("apisix.control.v1")
local ipairs    = ipairs
local pairs     = pairs
local ngx       = ngx
local ffi       = require("ffi")
local C         = ffi.C
local pcall = pcall
local select = select
local type = type
local prometheus
local prometheus_bkp
local router = require("apisix.router")
local get_routes = router.http_routes
local get_ssls   = router.ssls
local get_services = require("apisix.http.service").services
local get_consumers = require("apisix.consumer").consumers
local get_upstreams = require("apisix.upstream").upstreams
local get_global_rules = require("apisix.global_rules").global_rules
local get_global_rules_prev_index = require("apisix.global_rules").get_pre_index
local clear_tab = core.table.clear
local get_stream_routes = router.stream_routes
local get_protos = require("apisix.plugins.grpc-transcode.proto").protos
local service_fetch = require("apisix.http.service").get
local latency_details = require("apisix.utils.log-util").latency_details_in_ms
local xrpc = require("apisix.stream.xrpc")
local unpack = unpack
local next = next
local process = require("ngx.process")
local tonumber = tonumber
local shdict_prometheus_cache = ngx.shared["prometheus-cache"]
local ngx_timer_every = ngx.timer.every

if not shdict_prometheus_cache then
    error("lua_shared_dict \"prometheus-cache\" not configured")
end

local plugin_name = "prometheus"
local default_export_uri = "/apisix/prometheus/metrics"
-- Default set of latency buckets, 1ms to 60s:
local DEFAULT_BUCKETS = {1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, 2000, 5000, 10000, 30000, 60000}
-- Default refresh interval
local DEFAULT_REFRESH_INTERVAL = 15

local CACHED_METRICS_KEY = "cached_metrics_text"

local metrics = {}

local inner_tab_arr = {}

local exporter_timer_running = false

local exporter_timer_created = false


local function gen_arr(...)
    clear_tab(inner_tab_arr)
    for i = 1, select('#', ...) do
        inner_tab_arr[i] = select(i, ...)
    end

    return inner_tab_arr
end

local extra_labels_tbl = {}

local function extra_labels(name, ctx)
    clear_tab(extra_labels_tbl)

    local attr = plugin.plugin_attr("prometheus")
    local metrics = attr.metrics

    if metrics and metrics[name] and metrics[name].extra_labels then
        local labels = metrics[name].extra_labels
        for _, kv in ipairs(labels) do
            local val, v = next(kv)
            if ctx then
                val = ctx.var[v:sub(2)]
                if val == nil then
                    val = ""
                end
            end
            core.table.insert(extra_labels_tbl, val)
        end
    end

    return extra_labels_tbl
end


local _M = {}


local function init_stream_metrics()
    metrics.stream_connection_total = prometheus:counter("stream_connection_total",
        "Total number of connections handled per stream route in APISIX",
        {"route"})

    xrpc.init_metrics(prometheus)
end


function _M.http_init(prometheus_enabled_in_stream)
    -- todo: support hot reload, we may need to update the lua-prometheus
    -- library
    if ngx.get_phase() ~= "init" and ngx.get_phase() ~= "init_worker"  then
        if prometheus_bkp then
            prometheus = prometheus_bkp
        end
        return
    end

    clear_tab(metrics)
    -- Newly added metrics should follow the naming best practices described in
    -- https://prometheus.io/docs/practices/naming/#metric-names
    -- For example,
    -- 1. Add unit as the suffix
    -- 2. Add `_total` as the suffix if the metric type is counter
    -- 3. Use base unit
    -- We keep the old metric names for the compatibility.

    -- across all services
    local metric_prefix = "apisix_"
    local attr = plugin.plugin_attr("prometheus")
    if attr and attr.metric_prefix then
        metric_prefix = attr.metric_prefix
    end

    local status_metrics_exptime = core.table.try_read_attr(attr, "metrics",
                                   "http_status", "expire")
    local latency_metrics_exptime = core.table.try_read_attr(attr, "metrics",
                                   "http_latency", "expire")
    local bandwidth_metrics_exptime = core.table.try_read_attr(attr, "metrics",
                                   "bandwidth", "expire")
    local upstream_status_exptime = core.table.try_read_attr(attr, "metrics",
                                   "upstream_status", "expire")
    local llm_latency_exptime = core.table.try_read_attr(attr, "metrics", "llm_latency", "expire")
    local llm_prompt_tokens_exptime = core.table.try_read_attr(attr, "metrics",
                                                            "llm_prompt_tokens", "expire")
    local llm_completion_tokens_exptime = core.table.try_read_attr(attr, "metrics",
                                                            "llm_completion_tokens", "expire")
    local llm_active_connections_exptime = core.table.try_read_attr(attr, "metrics",
                                                            "llm_active_connections", "expire")

    prometheus = base_prometheus.init("prometheus-metrics", metric_prefix)

    metrics.connections = prometheus:gauge("nginx_http_current_connections",
            "Number of HTTP connections",
            {"state"})

    metrics.requests = prometheus:gauge("http_requests_total",
            "The total number of client requests since APISIX started")

    metrics.etcd_reachable = prometheus:gauge("etcd_reachable",
            "Config server etcd reachable from APISIX, 0 is unreachable")

    metrics.node_info = prometheus:gauge("node_info",
            "Info of APISIX node",
            {"hostname", "version"})

    metrics.etcd_modify_indexes = prometheus:gauge("etcd_modify_indexes",
            "Etcd modify index for APISIX keys",
            {"key"})

    metrics.shared_dict_capacity_bytes = prometheus:gauge("shared_dict_capacity_bytes",
            "The capacity of each nginx shared DICT since APISIX start",
            {"name"})

    metrics.shared_dict_free_space_bytes = prometheus:gauge("shared_dict_free_space_bytes",
            "The free space of each nginx shared DICT since APISIX start",
            {"name"})

    metrics.upstream_status = prometheus:gauge("upstream_status",
            "Upstream status from health check",
            {"name", "ip", "port"},
            upstream_status_exptime)

    -- per service

    -- The consumer label indicates the name of consumer corresponds to the
    -- request to the route/service, it will be an empty string if there is
    -- no consumer in request.
    metrics.status = prometheus:counter("http_status",
            "HTTP status codes per service in APISIX",
            {"code", "route", "matched_uri", "matched_host", "service", "consumer", "node",
            "request_type", "request_llm_model", "llm_model",
            "response_source",
            unpack(extra_labels("http_status"))},
            status_metrics_exptime)

    local buckets = DEFAULT_BUCKETS
    if attr and attr.default_buckets then
        buckets = attr.default_buckets
    end

    metrics.latency = prometheus:histogram("http_latency",
        "HTTP request latency in milliseconds per service in APISIX",
        {"type", "route", "service", "consumer", "node",
        "request_type", "request_llm_model", "llm_model",
        unpack(extra_labels("http_latency"))},
        buckets, latency_metrics_exptime)

    metrics.bandwidth = prometheus:counter("bandwidth",
            "Total bandwidth in bytes consumed per service in APISIX",
            {"type", "route", "service", "consumer", "node",
            "request_type", "request_llm_model", "llm_model",
            unpack(extra_labels("bandwidth"))},
            bandwidth_metrics_exptime)

    local llm_latency_buckets = DEFAULT_BUCKETS
    if attr and attr.llm_latency_buckets then
        llm_latency_buckets = attr.llm_latency_buckets
    end
    metrics.llm_latency = prometheus:histogram("llm_latency",
        "LLM request latency in milliseconds",
        {"route_id", "service_id", "consumer", "node",
        "request_type", "request_llm_model", "llm_model",
        unpack(extra_labels("llm_latency"))},
        llm_latency_buckets,
        llm_latency_exptime)

    metrics.llm_prompt_tokens = prometheus:counter("llm_prompt_tokens",
            "LLM service consumed prompt tokens",
            {"route_id", "service_id", "consumer", "node",
            "request_type", "request_llm_model", "llm_model",
            unpack(extra_labels("llm_prompt_tokens"))},
            llm_prompt_tokens_exptime)

    metrics.llm_completion_tokens = prometheus:counter("llm_completion_tokens",
            "LLM service consumed completion tokens",
            {"route_id", "service_id", "consumer", "node",
            "request_type", "request_llm_model", "llm_model",
            unpack(extra_labels("llm_completion_tokens"))},
            llm_completion_tokens_exptime)

    metrics.llm_active_connections = prometheus:gauge("llm_active_connections",
            "Number of active connections to LLM service",
            {"route", "route_id", "matched_uri", "matched_host",
            "service", "service_id", "consumer", "node",
            "request_type", "request_llm_model", "llm_model",
            unpack(extra_labels("llm_active_connections"))},
            llm_active_connections_exptime)

    if prometheus_enabled_in_stream then
        init_stream_metrics()
    end
end


function _M.stream_init()
    if ngx.get_phase() ~= "init" and ngx.get_phase() ~= "init_worker"  then
        return
    end

    if not pcall(function() return C.ngx_meta_lua_ffi_shdict_udata_to_zone end) then
        core.log.error("need to build APISIX-Runtime to support L4 metrics")
        return
    end

    clear_tab(metrics)

    local metric_prefix = "apisix_"
    local attr = plugin.plugin_attr("prometheus")
    if attr and attr.metric_prefix then
        metric_prefix = attr.metric_prefix
    end

    prometheus = base_prometheus.init("prometheus-metrics", metric_prefix)

    init_stream_metrics()
end


function _M.http_log(conf, ctx)
    local vars = ctx.var

    local route_id = ""
    local balancer_ip = ctx.balancer_ip or ""
    local service_id = ""
    local consumer_name = ctx.consumer_name or ""

    local matched_route = ctx.matched_route and ctx.matched_route.value
    if matched_route then
        route_id = matched_route.id
        service_id = matched_route.service_id or ""
        if conf.prefer_name == true then
            route_id = matched_route.name or route_id
            if service_id ~= "" then
                local service = service_fetch(service_id)
                service_id = service and service.value.name or service_id
            end
        end
    end

    local matched_uri = ""
    local matched_host = ""
    if ctx.curr_req_matched then
        matched_uri = ctx.curr_req_matched._path or ""
        matched_host = ctx.curr_req_matched._host or ""
    end

    local response_source = core.response.get_response_source(ctx)

    metrics.status:inc(1,
        gen_arr(vars.status, route_id, matched_uri, matched_host,
                service_id, consumer_name, balancer_ip,
                vars.request_type, vars.request_llm_model, vars.llm_model,
                response_source,
                unpack(extra_labels("http_status", ctx))))

    local latency, upstream_latency, apisix_latency = latency_details(ctx)
    local latency_extra_label_values = extra_labels("http_latency", ctx)

    metrics.latency:observe(latency,
        gen_arr("request", route_id, service_id, consumer_name, balancer_ip,
        vars.request_type, vars.request_llm_model, vars.llm_model,
        unpack(latency_extra_label_values)))

    if upstream_latency then
        metrics.latency:observe(upstream_latency,
            gen_arr("upstream", route_id, service_id, consumer_name, balancer_ip,
            vars.request_type, vars.request_llm_model, vars.llm_model,
            unpack(latency_extra_label_values)))
    end

    metrics.latency:observe(apisix_latency,
        gen_arr("apisix", route_id, service_id, consumer_name, balancer_ip,
        vars.request_type, vars.request_llm_model, vars.llm_model,
        unpack(latency_extra_label_values)))

    local bandwidth_extra_label_values = extra_labels("bandwidth", ctx)

    metrics.bandwidth:inc(vars.request_length,
        gen_arr("ingress", route_id, service_id, consumer_name, balancer_ip,
        vars.request_type, vars.request_llm_model, vars.llm_model,
        unpack(bandwidth_extra_label_values)))

    metrics.bandwidth:inc(vars.bytes_sent,
        gen_arr("egress", route_id, service_id, consumer_name, balancer_ip,
        vars.request_type, vars.request_llm_model, vars.llm_model,
        unpack(bandwidth_extra_label_values)))

    if vars.request_type == "ai_stream" or vars.request_type == "ai_chat" then
        local llm_time_to_first_token = vars.llm_time_to_first_token
        if llm_time_to_first_token ~= "0" then
            metrics.llm_latency:observe(tonumber(llm_time_to_first_token),
                gen_arr(route_id, service_id, consumer_name, balancer_ip,
                    vars.request_type, vars.request_llm_model, vars.llm_model,
                    unpack(extra_labels("llm_latency", ctx))))
        end
        metrics.llm_prompt_tokens:inc(tonumber(vars.llm_prompt_tokens),
            gen_arr(route_id, service_id, consumer_name, balancer_ip,
                vars.request_type, vars.request_llm_model, vars.llm_model,
                unpack(extra_labels("llm_prompt_tokens", ctx))))

        metrics.llm_completion_tokens:inc(tonumber(vars.llm_completion_tokens),
            gen_arr(route_id, service_id, consumer_name, balancer_ip,
                vars.request_type, vars.request_llm_model, vars.llm_model,
                unpack(extra_labels("llm_completion_tokens", ctx))))
    end
end


function _M.stream_log(conf, ctx)
    local route_id = ""
    local matched_route = ctx.matched_route and ctx.matched_route.value
    if matched_route then
        route_id = matched_route.id
        if conf.prefer_name == true then
            route_id = matched_route.name or route_id
        end
    end

    metrics.stream_connection_total:inc(1, gen_arr(route_id))
end


-- FFI definitions for nginx connection status
-- Based on https://github.com/nginx/nginx/blob/master/src/event/ngx_event.c#L61-L78
ffi.cdef[[
    typedef uint64_t ngx_atomic_uint_t;
    extern ngx_atomic_uint_t  *ngx_stat_accepted;
    extern ngx_atomic_uint_t  *ngx_stat_handled;
    extern ngx_atomic_uint_t  *ngx_stat_requests;
    extern ngx_atomic_uint_t  *ngx_stat_active;
    extern ngx_atomic_uint_t  *ngx_stat_reading;
    extern ngx_atomic_uint_t  *ngx_stat_writing;
    extern ngx_atomic_uint_t  *ngx_stat_waiting;
]]

local label_values = {}

-- Mapping of status names to FFI global variables and metrics
local status_mapping = {
    {name = "active", var = "ngx_stat_active"},
    {name = "accepted", var = "ngx_stat_accepted"},
    {name = "handled", var = "ngx_stat_handled"},
    {name = "total", var = "ngx_stat_requests"},
    {name = "reading", var = "ngx_stat_reading"},
    {name = "writing", var = "ngx_stat_writing"},
    {name = "waiting", var = "ngx_stat_waiting"},
}

-- Use FFI to get nginx status directly from global variables
local function nginx_status()
    for _, item in ipairs(status_mapping) do
        local ok, value = pcall(function()
            local stat_ptr = C[item.var]
            return stat_ptr and tonumber(stat_ptr[0]) or 0
        end)

        if not ok then
            core.log.error("failed to read ", item.name, " via FFI")
            return
        end

        if item.name == "total" then
            metrics.requests:set(value)
        else
            label_values[1] = item.name
            metrics.connections:set(value, label_values)
        end
    end
end


local key_values = {}
local function set_modify_index(key, items, items_ver, global_max_index)
    clear_tab(key_values)
    local max_idx = 0
    if items_ver and items then
        for _, item in ipairs(items) do
            if type(item) == "table" then
                local modify_index = item.orig_modifiedIndex or item.modifiedIndex
                if modify_index > max_idx then
                    max_idx = modify_index
                end
            end
        end
    end

    key_values[1] = key
    metrics.etcd_modify_indexes:set(max_idx, key_values)


    global_max_index = max_idx > global_max_index and max_idx or global_max_index

    return global_max_index
end


local function etcd_modify_index()
    clear_tab(key_values)
    local global_max_idx = 0

    -- routes
    local routes, routes_ver = get_routes()
    global_max_idx = set_modify_index("routes", routes, routes_ver, global_max_idx)

    -- services
    local services, services_ver = get_services()
    global_max_idx = set_modify_index("services", services, services_ver, global_max_idx)

    -- ssls
    local ssls, ssls_ver = get_ssls()
    global_max_idx = set_modify_index("ssls", ssls, ssls_ver, global_max_idx)

    -- consumers
    local consumers, consumers_ver = get_consumers()
    global_max_idx = set_modify_index("consumers", consumers, consumers_ver, global_max_idx)

    -- global_rules
    local global_rules, global_rules_ver = get_global_rules()
    if global_rules then
        global_max_idx = set_modify_index("global_rules", global_rules,
            global_rules_ver, global_max_idx)

        -- prev_index
        key_values[1] = "prev_index"
        local prev_index = get_global_rules_prev_index()
        metrics.etcd_modify_indexes:set(prev_index, key_values)

    else
        global_max_idx = set_modify_index("global_rules", nil, nil, global_max_idx)
    end

    -- upstreams
    local upstreams, upstreams_ver = get_upstreams()
    global_max_idx = set_modify_index("upstreams", upstreams, upstreams_ver, global_max_idx)

    -- stream_routes
    local stream_routes, stream_routes_ver = get_stream_routes()
    global_max_idx = set_modify_index("stream_routes", stream_routes,
        stream_routes_ver, global_max_idx)

    -- proto
    local protos, protos_ver = get_protos()
    global_max_idx = set_modify_index("protos", protos, protos_ver, global_max_idx)

    -- global max
    key_values[1] = "max_modify_index"
    metrics.etcd_modify_indexes:set(global_max_idx, key_values)

end


local function shared_dict_status()
    local name = {}
    for shared_dict_name, shared_dict in pairs(ngx.shared) do
        name[1] = shared_dict_name
        metrics.shared_dict_capacity_bytes:set(shared_dict:capacity(), name)
        metrics.shared_dict_free_space_bytes:set(shared_dict:free_space(), name)
    end
end


local function collect(yieldable)
    -- collect ngx.shared.DICT status
    shared_dict_status()

    -- across all services
    nginx_status()

    local config = core.config.new()

    -- config server status
    local hostname = core.utils.gethostname() or ""
    local version = core.version.VERSION or ""

    local local_conf = core.config.local_conf()
    local stream_only = local_conf.apisix.proxy_mode == "stream"
    -- we can't get etcd index in metric server if only stream subsystem is enabled
    if config.type == "etcd" and not stream_only then
        -- etcd modify index
        etcd_modify_index()

        if yieldable then
            local version, err = config:server_version()
            if version then
                metrics.etcd_reachable:set(1)

            else
                metrics.etcd_reachable:set(0)
                core.log.error("prometheus: failed to reach config server while ",
                            "processing metrics endpoint: ", err)
            end

            -- Because request any key from etcd will return the "X-Etcd-Index".
            -- A non-existed key is preferred because it doesn't return too much data.
            -- So use phantom key to get etcd index.
            local res, _ = config:getkey("/phantomkey")
            if res and res.headers then
                clear_tab(key_values)
                -- global max
                key_values[1] = "x_etcd_index"
                metrics.etcd_modify_indexes:set(res.headers["X-Etcd-Index"], key_values)
            end
        end
    end

    metrics.node_info:set(1, gen_arr(hostname, version))

    -- update upstream_status metrics
    local stats = control.get_health_checkers()
    for _, stat in ipairs(stats) do
        for _, node in ipairs(stat.nodes) do
            metrics.upstream_status:set(
                    (node.status == "healthy" or node.status == "mostly_healthy") and 1 or 0,
                    gen_arr(stat.name, node.ip, node.port)
            )
        end
    end

    return core.table.concat(prometheus:metric_data())
end


local function exporter_timer(premature, yieldable, cache_exptime)
    if premature then
        return
    end

    if not prometheus then
        return
    end

    if exporter_timer_running then
        core.log.warn("Previous calculation still running, skipping")
        return
    end

    exporter_timer_running = true

    local ok, res = pcall(collect, yieldable)
    if not ok then
        core.log.error("Failed to collect metrics: ", res)
        exporter_timer_running = false
        return
    end

    -- Clear the cached data after cache_exptime to prevent stale data in case of an error.
    local _, err, forcible = shdict_prometheus_cache:set(CACHED_METRICS_KEY, res, cache_exptime)
    if err then
        core.log.error("Failed to save metrics to the `prometheus-cache` shared dict: ", err,
                    ". The size of the value being attempted to be saved is: ", #res)
    end

    if forcible then
        core.log.error("Shared dictionary used for prometheus cache " ..
  "is full. REPORTED METRIC DATA MIGHT BE INCOMPLETE. Please increase the " ..
  "size of the `prometheus-cache` shared dict or decrease metric cardinality.")
    end

    exporter_timer_running = false
end


local function init_exporter_timer()
    if process.type() ~= "privileged agent" then
        return
    end

    local refresh_interval = DEFAULT_REFRESH_INTERVAL
    local attr = plugin.plugin_attr("prometheus")
    if attr and attr.refresh_interval then
        refresh_interval = attr.refresh_interval
    end

    local cache_exptime = refresh_interval * 2

    exporter_timer(false, false, cache_exptime)

    if exporter_timer_created then
        core.log.info("Exporter timer already created, skipping")
        return
    end

    -- When the APISIX configuration `refresh_interval` is updated,
    -- the timer will not restart, and the new `refresh_interval` will not be applied.
    -- APISIX needs to be restarted to apply the changes.
    local ok, err = ngx_timer_every(refresh_interval, exporter_timer, true, cache_exptime)

    if ok then
        exporter_timer_created = true
    else
        core.log.error("Failed to start the exporter timer: ", err)
    end
end
_M.init_exporter_timer = init_exporter_timer


local function get_cached_metrics()
    if not prometheus or not metrics then
        core.log.error("prometheus: plugin is not initialized, please make sure ",
                     " 'prometheus_metrics' shared dict is present in nginx template")
        return 500, {message = "An unexpected error occurred"}
    end

    core.response.set_header("content_type", "text/plain")
    local cached_metrics_text, err = shdict_prometheus_cache:get(CACHED_METRICS_KEY)
    if err then
        core.log.error("Failed to retrieve cached metrics: err: ", err)
        return 500, {message = "Failed to retrieve metrics. err: " .. err}
    end
    if not cached_metrics_text then
        core.log.error("Failed to retrieve cached metrics: data is nil")
        return 500, {message = "Failed to retrieve metrics: no data available"}
    end

    return 200, cached_metrics_text
end


local function get_api(called_by_api_router)
    local export_uri = default_export_uri
    local attr = plugin.plugin_attr(plugin_name)
    if attr and attr.export_uri then
        export_uri = attr.export_uri
    end

    local api = {
        methods = {"GET"},
        uri = export_uri,
        handler = get_cached_metrics
    }

    if not called_by_api_router then
        return api
    end

    if attr.enable_export_server then
        return {}
    end

    return {api}
end
_M.get_api = get_api


function _M.export_metrics()
    if not prometheus then
        return core.response.exit(200, "{}")
    end
    local api = get_api(false)
    local uri = ngx.var.uri
    local method = ngx.req.get_method()

    if uri == api.uri and method == api.methods[1] then
        local code, body = api.handler()
        if code or body then
            core.response.exit(code, body)
        end
    end

    return core.response.exit(404)
end


function _M.metric_data()
    return prometheus:metric_data()
end

local function inc_llm_active_connections(ctx, value)
    if not metrics or not metrics.llm_active_connections then
        return
    end

    local vars = ctx.var

    local route_id = ""
    local route_name = ""
    local balancer_ip = ctx.balancer_ip or ""
    local service_id = ""
    local service_name = ""
    local consumer_name = ctx.consumer_name or ""

    local matched_route = ctx.matched_route and ctx.matched_route.value
    if matched_route then
        route_id = matched_route.id
        route_name = matched_route.name or ""
        service_id = matched_route.service_id or ""
        if service_id ~= "" then
            local fetched_service = service_fetch(service_id)
            service_name = fetched_service and fetched_service.value.name or ""
        end
    end

    local matched_uri = ""
    local matched_host = ""
    if ctx.curr_req_matched then
        matched_uri = ctx.curr_req_matched._path or ""
        matched_host = ctx.curr_req_matched._host or ""
    end

    metrics.llm_active_connections:inc(
        value,
        gen_arr(route_name, route_id, matched_uri,
            matched_host, service_name, service_id, consumer_name, balancer_ip,
            vars.request_type, vars.request_llm_model, vars.llm_model,
        unpack(extra_labels("llm_active_connections", ctx)))
    )
end


function _M.inc_llm_active_connections(ctx)
    inc_llm_active_connections(ctx, 1)
end


function _M.dec_llm_active_connections(ctx)
    inc_llm_active_connections(ctx, -1)
end

function _M.get_prometheus()
    return prometheus
end


function _M.destroy()
    if prometheus ~= nil then
        prometheus_bkp = prometheus
        prometheus = nil
    end
end


return _M
