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 operation_key = KEYS[10]
local health_due_key = KEYS[11]
local health_queued_key = KEYS[12]
local health_leases_key = KEYS[13]
local health_tasks_key = KEYS[14]
local health_task_expiry_key = KEYS[15]
local health_ref_task_key = KEYS[16]
local health_unhealthy_key = KEYS[17]

local operation = ARGV[1]
local now_ms = tonumber(ARGV[2])
local limit = tonumber(ARGV[3])
local upstream_id = ARGV[4]
local operation_ttl_ms = tonumber(ARGV[5])
local unhealthy_policies_json = ARGV[6]

local function finish(reply)
    local encoded = cjson.encode(reply)
    redis.call('SET', operation_key, encoded, 'PX', operation_ttl_ms)
    return encoded
end

local committed = redis.call('GET', operation_key)
if committed then
    return committed
end

local function is_managed(state)
    return state == 'FETCHED' or state == 'CHECKING' or state == 'AVAILABLE' or
        state == 'SUSPECT' or state == 'DRAINING'
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 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_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_owned(proxy_id, record)
    if record and type(record.ownerIndexKey) == 'string' and record.ownerIndexKey ~= '' then
        redis.call('ZREM', record.ownerIndexKey, proxy_id)
    end
end

local function remove_worker_owned(proxy_id)
    local raw = redis.call('HGET', owners_key, proxy_id)
    if not raw then
        return
    end
    local decoded, assignment = pcall(cjson.decode, raw)
    if decoded and type(assignment) == 'table' and
        type(assignment.workerIndexKey) == 'string' and assignment.workerIndexKey ~= '' then
        redis.call('ZREM', assignment.workerIndexKey, proxy_id)
    end
end

local function remove_health_task(proxy_id)
    redis.call('ZREM', health_due_key, proxy_id)
    local task_id = redis.call('HGET', health_ref_task_key, proxy_id)
    if not task_id then
        return
    end
    local raw = redis.call('HGET', health_tasks_key, task_id)
    if raw then
        local decoded, task = pcall(cjson.decode, raw)
        if decoded and type(task) == 'table' then
            if type(task.checkerLeaseKey) == 'string' and task.checkerLeaseKey ~= '' then
                redis.call('ZREM', task.checkerLeaseKey, task_id)
            end
            if type(task.upstreamTasksKey) == 'string' and task.upstreamTasksKey ~= '' then
                redis.call('ZREM', task.upstreamTasksKey, task_id)
            end
        end
    end
    redis.call('ZREM', health_queued_key, task_id)
    redis.call('ZREM', health_leases_key, task_id)
    redis.call('ZREM', health_task_expiry_key, task_id)
    redis.call('HDEL', health_tasks_key, task_id)
    redis.call('HDEL', health_ref_task_key, proxy_id)
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)
        remove_owned(proxy_id, decoded and record or nil)
        if decoded and type(record) == 'table' and is_managed(record.state) then
            decrement_inventory(record.sourceUpstream)
        end
        if decoded and type(record) == 'table' then
            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)
    remove_worker_owned(proxy_id)
    redis.call('HDEL', owners_key, proxy_id)
    redis.call('ZREM', owner_expiry_key, proxy_id)
    redis.call('ZREM', health_unhealthy_key, proxy_id)
    remove_health_task(proxy_id)
end

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

if operation == 'sweep' then
    return finish({status = 'ok', count = #expired})
end
if operation == 'unhealthy' then
    local decoded, policies = pcall(cjson.decode, unhealthy_policies_json or '')
    if not decoded or type(policies) ~= 'table' then
        return finish({status = 'invalid', count = 0, deferredOwned = 0})
    end
    local scan_limit = limit * 4
    if scan_limit > 1024 then
        scan_limit = 1024
    end
    local candidates = redis.call('ZRANGEBYSCORE', health_unhealthy_key, '-inf', now_ms, 'LIMIT', 0, scan_limit)
    local removed = 0
    local deferred_owned = 0
    for _, proxy_id in ipairs(candidates) do
        local raw = redis.call('HGET', records_key, proxy_id)
        if not raw then
            redis.call('ZREM', health_unhealthy_key, proxy_id)
        else
            local valid, record = pcall(cjson.decode, raw)
            local remove_after_ms = valid and type(record) == 'table' and tonumber(policies[record.sourceUpstream]) or nil
            local unhealthy_since_ms = valid and type(record) == 'table' and tonumber(record.unhealthySinceMs or '0') or nil
            if not valid or type(record) ~= 'table' or record.state ~= 'UNHEALTHY' or not remove_after_ms or
                remove_after_ms <= 0 or not unhealthy_since_ms or unhealthy_since_ms <= 0 then
                redis.call('ZREM', health_unhealthy_key, proxy_id)
            elseif unhealthy_since_ms + remove_after_ms > now_ms then
                redis.call('ZADD', health_unhealthy_key, unhealthy_since_ms + remove_after_ms, proxy_id)
            else
                local owner_raw = redis.call('HGET', owners_key, proxy_id)
                local owned = owner_raw or (type(record.ownerWorkerId) == 'string' and record.ownerWorkerId ~= '')
                if owned then
                    local retry_at_ms = now_ms + 1000
                    redis.call('ZADD', health_unhealthy_key, retry_at_ms, proxy_id)
                    deferred_owned = deferred_owned + 1
                elseif removed < limit then
                    remove_proxy(proxy_id)
                    removed = removed + 1
                end
            end
        end
    end
    return finish({status = 'ok', count = removed, deferredOwned = deferred_owned})
end
if operation == 'inventory' then
    local count = tonumber(redis.call('HGET', inventory_key, upstream_id) or '0')
    if count < 0 then
        count = 0
        redis.call('HSET', inventory_key, upstream_id, 0)
    end
    return finish({status = 'ok', count = count})
end
return finish({status = 'invalid', count = 0})