local ctrl = { "ctrl" }
local cmd = { "cmd" }

emacsKeyMappers = {
    {ctrl, "f", {}, "right"},
    {ctrl, "b", {}, "left"},
    {ctrl, "e", cmd, "right"},
    {ctrl, "a", cmd, "left"},

    {ctrl, "p", {}, "up"},
    {ctrl, "n", {}, "down"},
    {ctrl, "v", {}, "pagedown"},
    {cmd , "v", {}, "pageup"}
}

apps = {
    "Microsoft Excel",
    "Microsoft PowerPoint"
}

function bindKeyMappers(keyMappers)
    for i, mapper in ipairs(keyMappers) do
        local mods = mapper[1]
        local key = mapper[2]
        local mappedMods = mapper[3]
        local mappedKey = mapper[4]
        hs.hotkey.bind(mods, key, function()
            hs.eventtap.keyStroke(mappedMods, mappedKey)
        end)
    end
end

function deleteAllHotkeys()
    for k, v in pairs(hs.hotkey.getHotkeys()) do
        v:delete()
    end
end

function contains(table, element)
    for i, v in pairs( table ) do
        if v == element then
            return true
        end
    end
end

function applicationWatcher(appName, eventType, appObject)
    if hs.application.watcher.activated == eventType then
        deleteAllHotkeys()
        if contains( apps, appName ) then
            bindKeyMappers(emacsKeyMappers)
        end
    end
    hs.console.printStyledtext(appName)
    hs.console.printStyledtext(eventType)
end

appWatcher = hs.application.watcher.new(applicationWatcher)
appWatcher:start()