local M = {}

M.DEFAULT_WPM = 250
M.DEFAULT_STEP = 25
M.DEFAULT_MIN_WPM = 50

local function positive_finite(value)
    return type(value) == "number"
        and value == value
        and value ~= math.huge
        and value ~= -math.huge
        and value > 0
end

function M.read(raw)
    if raw == nil then raw = {} end
    if type(raw) ~= "table" then
        return nil, "rsvp settings must be a table"
    end

    for key in pairs(raw) do
        if key ~= "wpm" and key ~= "wpm_step" and key ~= "min_wpm" then
            return nil, string.format("unknown rsvp setting %s", tostring(key))
        end
    end

    local settings = {
        wpm = raw.wpm == nil and M.DEFAULT_WPM or raw.wpm,
        wpm_step = raw.wpm_step == nil and M.DEFAULT_STEP or raw.wpm_step,
        min_wpm = raw.min_wpm == nil and M.DEFAULT_MIN_WPM or raw.min_wpm,
    }
    for key, value in pairs(settings) do
        if not positive_finite(value) then
            return nil, string.format("rsvp.%s must be a finite positive number", key)
        end
    end
    settings.wpm = math.max(settings.wpm, settings.min_wpm)
    return settings
end

return M