--[[
  Move stalled jobs to wait.

    Input:
      KEYS[1] 'stalled' (SET)
      KEYS[2] 'wait',   (LIST)
      KEYS[3] 'active', (LIST)
      KEYS[4] 'stalled-check', (KEY)
      KEYS[5] 'meta', (KEY)
      KEYS[6] 'paused', (LIST)
      KEYS[7] 'marker'
      KEYS[8] 'event stream' (STREAM)

      ARGV[1]  Max stalled job count
      ARGV[2]  queue.toKey('')
      ARGV[3]  timestamp
      ARGV[4]  max check time

    Events:
      'stalled' with stalled job id.
]]
local rcall = redis.call

-- Includes
--- @include "includes/addJobInTargetList"
--- @include "includes/batches"
--- @include "includes/getTargetQueueList"
--- @include "includes/moveJobToWait"
--- @include "includes/trimEvents"

local stalledKey = KEYS[1]
local waitKey = KEYS[2]
local activeKey = KEYS[3]
local stalledCheckKey = KEYS[4]
local metaKey = KEYS[5]
local pausedKey = KEYS[6]
local markerKey = KEYS[7]
local eventStreamKey = KEYS[8]
local maxStalledJobCount = tonumber(ARGV[1])
local queueKeyPrefix = ARGV[2]
local timestamp = ARGV[3]
local maxCheckTime = ARGV[4]

if rcall("EXISTS", stalledCheckKey) == 1 then
    return {}
end

rcall("SET", stalledCheckKey, timestamp, "PX", maxCheckTime)

-- Trim events before emiting them to avoid trimming events emitted in this script
trimEvents(metaKey, eventStreamKey)

-- Move all stalled jobs to wait
local stalling = rcall('SMEMBERS', stalledKey)
local stalled = {}
if (#stalling > 0) then
    rcall('DEL', stalledKey)

    -- Remove from active list
    for i, jobId in ipairs(stalling) do
        -- Markers in waitlist DEPRECATED in v5: Remove in v6.
        if string.sub(jobId, 1, 2) == "0:" then
            -- If the jobId is a delay marker ID we just remove it.
            rcall("LREM", activeKey, 1, jobId)
        else
            local jobKey = queueKeyPrefix .. jobId

            -- Check that the lock is also missing, then we can handle this job as really stalled.
            if (rcall("EXISTS", jobKey .. ":lock") == 0) then
                --  Remove from the active queue.
                local removed = rcall("LREM", activeKey, 1, jobId)

                if (removed > 0) then
                    -- If this job has been stalled too many times, such as if it crashes the worker, then fail it.
                    local stalledCount = rcall("HINCRBY", jobKey, "stc", 1)
                    if stalledCount > maxStalledJobCount then
                        local failedReason = "job stalled more than allowable limit"
                        rcall("HSET", jobKey, "defa", failedReason)
                    end
                    moveJobToWait(metaKey, activeKey, waitKey, pausedKey, markerKey, eventStreamKey, jobId,
                        "RPUSH")

                    -- Emit the stalled event
                    rcall("XADD", eventStreamKey, "*", "event", "stalled", "jobId", jobId)
                    table.insert(stalled, jobId)
                end
            end
        end
    end
end

-- Mark potentially stalled jobs
local active = rcall('LRANGE', activeKey, 0, -1)

if (#active > 0) then
    for from, to in batches(#active, 7000) do
        rcall('SADD', stalledKey, unpack(active, from, to))
    end
end

return stalled
