community-plugins/nix-monitor/nix_monitor_service.luau

noctalia.setUpdateInterval(5000)

-- Helper functions
function tr(key)
    return noctalia.tr(key)
end

function cfg(key)
    return noctalia.getConfig(key)
end

function getState(key)
    return noctalia.state.get(key)
end

function setState(key, val)
    noctalia.state.set(key, val)
end

function watchState(key, cb)
    noctalia.state.watch(key, cb)
end

-- Vars
local branch = cfg("branch")
local updateCheckInterval = cfg("check_interval")
local checkDurationThreshold = cfg("check_duration_threshold")
local systemStatsCheckInterval = cfg("system_stats_check_interval")
local stateDir = "/tmp/nix-monitor"
local remoteHashFile = stateDir .. "/remoteHash"
local remotePidFile = stateDir .. "/remoteHash.pid"
local storeSizeFile = stateDir .. "/storeSize"
local closureSizeFile = stateDir .. "/closureSize"
local showUpdateNotification = true

local localHashCmd  = "nixos-version --hash 2> /dev/null | cut -c -7"
local remoteHashCmd = "git ls-remote https://github.com/NixOS/nixpkgs " .. branch .. " 2>/dev/null | cut -c 1-7"
local nixosGenerationsCmd = "nixos-rebuild list-generations | tail -n +2 | wc -l"
local nixosCurrentGenCmd = "nixos-rebuild list-generations | grep True | awk '{print $1}'"
local hmGenerationsCmd = "home-manager generations | wc -l"
local hmCurrentGenCmd = "home-manager generations | grep '(current)' | awk '{print $5}'"
local storeSizeCmd = "du -s --block-size=1GiB /nix/store | awk '\{print $1 \" GiB\"\}'"
local closureSizeCmd = "nix path-info --closure-size --human-readable /run/current-system | awk '\{print $2, $3\}'"

-- State inits
setState("lastLocalCheckTime", os.time())
setState("lastRemoteCheckRunTime", os.time())
setState("lastRemoteCheckTime", os.time())
setState("lastRemoteCheckTimeStr", "n/a")
setState("localHash", "n/a")
setState("remoteHash", "n/a")
setState("isRemoteCheckRunning", false)
setState("isUpdateAvailable", false)
setState("lastGenerationsCheckTime", 0)
setState("isSystemStatsCheckRunning", false)
setState("lastSystemStatsCheckTime", 0)
setState("hasHomeManager", noctalia.commandExists("home-manager"))
setState("nixosGenerations", "•••")
setState("nixosCurrentGen", "•••")
setState("hmGenerations", "•••")
setState("hmCurrentGen", "•••")
setState("storeSize", "•••")
setState("closureSize", "•••")

noctalia.mkdirAll(stateDir)
noctalia.writeFile(remoteHashFile, "")

-- Local check
function checkLocalHash()
    setState("lastLocalCheckTime", os.time())
    noctalia.runAsync(localHashCmd, function(res)
        if res.exitCode == 0 then
            setState("localHash", res.stdout)
        end
    end)
end

-- Remote check
--
-- Currently it is writing to a file because when I use the runAsync with
-- the callback, it is timed out
function checkRemoteHash(delay: number?)
    local delay = delay or 0

    if getState("isRemoteCheckRunning") then
        return
    end

    setState("isRemoteCheckRunning", true)
    setState("lastRemoteCheckRunTime", os.time())

    noctalia.writeFile(remoteHashFile, "")
    noctalia.runAsync(`sleep {delay} && {remoteHashCmd} > {remoteHashFile} & echo $! > {remotePidFile}`)
end

-- Check if the remoteHash check command is finished by reading the file
function checkRemoteStatus()
    local remoteHash = noctalia.string.trim(noctalia.readFile(remoteHashFile))

    if type(remoteHash) == "string" and remoteHash ~= "" then
        setState("isRemoteCheckRunning", false)
        setState("remoteHash", remoteHash)
        onRemoteHashCheckCompleted()
    end
end

function onRemoteHashCheckCompleted()
    if cfg("show_checking_notification") then
        noctalia.notify(tr("notification.update_check_completed"))
    end

    setState("lastRemoteCheckTime", os.time())
    noctalia.runAsync("date '+%Y-%m-%d %H:%M'", function(date) setState("lastRemoteCheckTimeStr", date.stdout) end)
end

function cancelRemoteCheck()
    setState("isRemoteCheckRunning", false)
    if noctalia.fileExists(remotePidFile) then
        local pid = noctalia.string.trim(noctalia.readFile(remotePidFile))

        if type(pid) == "string" and pid ~= "" then
            noctalia.runAsync(`pkill -9 -P {pid}`)
        end
        noctalia.removeFile(remotePidFile)
    end
end

-- Generation check
function checkGenerations()
    setState("lastGenerationsCheckTime", os.time())

    noctalia.runAsync(nixosGenerationsCmd, function(result)
        setState("nixosGenerations", result.stdout)
    end)

    noctalia.runAsync(nixosCurrentGenCmd, function(result)
        setState("nixosCurrentGen", result.stdout)
    end)

    if getState("hasHomeManager") then
        noctalia.runAsync(hmGenerationsCmd, function(result)
            setState("hmGenerations", result.stdout)
        end)

        noctalia.runAsync(hmCurrentGenCmd, function(result)
            setState("hmCurrentGen", result.stdout)
        end)
    end
end

-- System stats check
function checkSystemStats()
    if getState("isSystemStatsCheckRunning") then
        return
    end

    setState("isSystemStatsCheckRunning", true)
    setState("lastSystemStatsCheckTime", os.time())

    noctalia.runAsync(`{storeSizeCmd} > {storeSizeFile} &`)
    noctalia.runAsync(`{closureSizeCmd} > {closureSizeFile} &`)
end

function checkSystemStatsFile()
    local storeSize = noctalia.string.trim(noctalia.readFile(storeSizeFile))
    local closureSize = noctalia.string.trim(noctalia.readFile(closureSizeFile))

    if typeof(storeSize) == "string" and storeSize ~= "" then
        setState("storeSize", storeSize)
    end

    if typeof(closureSize) == "string" and closureSize ~= "" then
        setState("closureSize", closureSize)
    end

    local success = typeof(storeSize) == "string" and storeSize ~= "" and
        typeof(closureSize) == "string" and closureSize ~= ""

    if success then
        setState("isSystemStatsCheckRunning", false)
    end
end


-- Init
checkLocalHash()
checkRemoteHash(10)

-- Command watcher
watchState("command", function(command)
    if command == "check" then
        checkLocalHash()
        cancelRemoteCheck()
        checkRemoteHash()
        checkGenerations()
        checkSystemStats()
    end

    if command == "cancel" then
        cancelRemoteCheck()
    end
end)

--
-- Hooks
--

function update()
    -- Check local hash every 10 seconds
    if (os.time() - getState("lastLocalCheckTime") >= 10) then
        checkLocalHash()
    end

    -- Remote check
    if (os.time() - getState("lastRemoteCheckTime")) >= 60 * updateCheckInterval then
        checkRemoteHash()
    end

    if getState("isRemoteCheckRunning") then
        checkRemoteStatus()

        -- Remote check timeout
        if (os.time() - getState("lastRemoteCheckRunTime")) >= 60 * checkDurationThreshold then
            cancelRemoteCheck()
        end
    end

    if getState("localHash") ~= getState("remoteHash") and
        getState("localHash") ~= "n/a" and getState("remoteHash") ~= "n/a"
    then
        setState("isUpdateAvailable", true)

        if cfg("show_update_notification") and showUpdateNotification then
            noctalia.notify(tr("notification.update_is_available"))
            showUpdateNotification = false
        end
    else
        setState("isUpdateAvailable", false)
        showUpdateNotification = true
    end

    -- Generations check
    if (os.time() - getState("lastGenerationsCheckTime")) >= 20 then
        checkGenerations()
    end

    -- System stats check
    if (os.time() - getState("lastSystemStatsCheckTime")) >= 60 * systemStatsCheckInterval then
        checkSystemStats()
    end

    if getState("isSystemStatsCheckRunning") then
        checkSystemStatsFile()
    end
end

function onExit(signal)
    cancelRemoteCheck()
end