sub init()
    m.top.setFocus(true)
    m.backend = m.top.findNode("backend")
    m.status = m.top.findNode("status")
    m.cameraPosters = [
        m.top.findNode("poster1"),
        m.top.findNode("poster2"),
        m.top.findNode("poster3"),
        m.top.findNode("poster4")
    ]
    m.cameraNodes = [
        m.top.findNode("cam1"),
        m.top.findNode("cam2"),
        m.top.findNode("cam3"),
        m.top.findNode("cam4")
    ]

    loadConfig()
end sub

sub loadConfig()
    raw = ReadAsciiFile("pkg:/config/cameras.json")
    config = ParseJson(raw)

    if type(config) <> "roAssociativeArray" then
        m.status.text = "Unable to parse cameras.json"
        return
    end if

    if config.doesExist("backend") and config.backend.doesExist("baseUrl") then
        m.backend.text = "Frigate: " + config.backend.baseUrl
    end if

    if not config.doesExist("cameras") then
        m.status.text = "No cameras found in config"
        return
    end if

    cameras = config.cameras
    m.status.text = cameras.count().toStr() + " cameras loaded, fetching snapshots..."
    loadedCount = 0

    for i = 0 to m.cameraNodes.count() - 1
        poster = m.cameraPosters[i]
        node = m.cameraNodes[i]

        if i < cameras.count() then
            camera = cameras[i]
            label = camera.name

            if camera.doesExist("host") then
                label = label + chr(10) + camera.host
            end if

            if camera.doesExist("frigateCamera") then
                label = label + chr(10) + "Frigate ID: " + camera.frigateCamera
            end if

            snapshotUrl = buildSnapshotUrl(config, camera)
            targetPath = "tmp:/" + camera.id + ".jpg"
            result = fetchSnapshot(snapshotUrl, targetPath)

            if result.success then
                poster.uri = targetPath
                loadedCount = loadedCount + 1
                node.text = label
            else
                poster.uri = ""
                node.text = label + chr(10) + "Snapshot failed (" + result.code.toStr() + ")"
            end if
        else
            poster.uri = ""
            node.text = "Empty slot"
        end if
    end for

    m.status.text = loadedCount.toStr() + " of " + cameras.count().toStr() + " snapshots loaded"
end sub

function buildSnapshotUrl(config as Object, camera as Object) as String
    if not config.doesExist("backend") or not config.backend.doesExist("baseUrl") then
        return ""
    end if

    baseUrl = config.backend.baseUrl
    path = ""

    if camera.doesExist("snapshotPath") then
        path = camera.snapshotPath
    else if camera.doesExist("frigateCamera") then
        path = "/api/" + camera.frigateCamera + "/latest.jpg"
    else
        return ""
    end if

    if right(baseUrl, 1) = "/" and left(path, 1) = "/" then
        return left(baseUrl, len(baseUrl) - 1) + path
    else if right(baseUrl, 1) <> "/" and left(path, 1) <> "/" then
        return baseUrl + "/" + path
    end if

    return baseUrl + path
end function

function fetchSnapshot(url as String, filePath as String) as Object
    result = {
        success: false
        code: 0
    }

    if url = "" then
        return result
    end if

    transfer = CreateObject("roUrlTransfer")
    transfer.SetCertificatesFile("common:/certs/ca-bundle.crt")
    transfer.InitClientCertificates()
    transfer.SetUrl(url)

    result.success = transfer.GetToFile(filePath)
    result.code = transfer.GetResponseCode()

    return result
end function