local records_key = KEYS[1]
local unique_key = KEYS[2]
local idkeys_key = KEYS[3]
local expiry_key = KEYS[4]
local available_key = KEYS[5]
local inventory_key = KEYS[6]
local state_inventory_key = KEYS[7]
local owners_key = KEYS[8]
local owner_expiry_key = KEYS[9]

local now_ms = tonumber(ARGV[1])
local cleanup_limit = tonumber(ARGV[2])
local upstream_ids = cjson.decode(ARGV[3])

local function is_managed(state)
    return state == 'FETCHED' or state == 'CHECKING' or state == 'AVAILABLE' or
        state == 'SUSPECT' or state == 'DRAINING'
end

local function state_field(upstream, state)
    return string.len(upstream) .. ':' .. upstream .. ':' .. state
end

local function is_counted(state)
    return state == 'FETCHED' or state == 'CHECKING' or state == 'AVAILABLE' or
        state == 'SUSPECT' or state == 'DRAINING' or state == 'UNHEALTHY' or state == 'EXTRACTED'
end

local function decrement_inventory(upstream)
    if type(upstream) ~= 'string' or upstream == '' then
        return
    end
    local count = redis.call('HINCRBY', inventory_key, upstream, -1)
    if count < 0 then
        redis.call('HSET', inventory_key, upstream, 0)
    end
end

local function decrement_state(upstream, state)
    if type(upstream) ~= 'string' or upstream == '' or not is_counted(state) then
        return
    end
    local field = state_field(upstream, state)
    local count = redis.call('HINCRBY', state_inventory_key, field, -1)
    if count <= 0 then
        redis.call('HDEL', state_inventory_key, field)
    end
end

local function remove_available(proxy_id, record)
    redis.call('ZREM', available_key, proxy_id)
    local index_keys = record and record.indexKeys
    if type(index_keys) == 'table' then
        for _, index_key in ipairs(index_keys) do
            if type(index_key) == 'string' and index_key ~= '' then
                redis.call('ZREM', index_key, proxy_id)
            end
        end
    end
end

local function remove_proxy(proxy_id)
    local raw = redis.call('HGET', records_key, proxy_id)
    local record = nil
    if raw then
        local decoded
        decoded, record = pcall(cjson.decode, raw)
        remove_available(proxy_id, decoded and record or nil)
        if decoded and type(record) == 'table' then
            if is_managed(record.state) then
                decrement_inventory(record.sourceUpstream)
            end
            decrement_state(record.sourceUpstream, record.state)
        end
    else
        redis.call('ZREM', available_key, proxy_id)
    end
    local digest = redis.call('HGET', idkeys_key, proxy_id)
    if digest and redis.call('HGET', unique_key, digest) == proxy_id then
        redis.call('HDEL', unique_key, digest)
    end
    redis.call('HDEL', idkeys_key, proxy_id)
    redis.call('HDEL', records_key, proxy_id)
    redis.call('ZREM', expiry_key, proxy_id)
    redis.call('HDEL', owners_key, proxy_id)
    redis.call('ZREM', owner_expiry_key, proxy_id)
end

local expired = redis.call('ZRANGEBYSCORE', expiry_key, '-inf', now_ms, 'LIMIT', 0, cleanup_limit)
for _, proxy_id in ipairs(expired) do
    remove_proxy(proxy_id)
end

local oldest = redis.call('ZRANGE', expiry_key, 0, 0, 'WITHSCORES')
if #oldest == 2 and tonumber(oldest[2]) <= now_ms then
    return cjson.encode({status = 'unavailable', inventories = cjson.decode('[]')})
end

local inventories = cjson.decode('[]')
local states = {'FETCHED', 'CHECKING', 'AVAILABLE', 'SUSPECT', 'DRAINING', 'UNHEALTHY', 'EXTRACTED'}
for _, upstream_id in ipairs(upstream_ids) do
    if type(upstream_id) ~= 'string' or upstream_id == '' then
        return cjson.encode({status = 'invalid', inventories = cjson.decode('[]')})
    end
    local counts = {}
    for _, state in ipairs(states) do
        local count = tonumber(redis.call('HGET', state_inventory_key, state_field(upstream_id, state)) or '0')
        if count < 0 then
            return cjson.encode({status = 'unavailable', inventories = cjson.decode('[]')})
        end
        counts[string.lower(state)] = count
    end
    counts.upstreamId = upstream_id
    inventories[#inventories + 1] = counts
end

return cjson.encode({status = 'ok', inventories = inventories})