--
-- coroutines manager
--
local coroutines = {}

function addcoroutine(fn)
    local c = coroutine.create(fn)
    table.insert(coroutines, c)
    return c
end

function startcoroutine(c)
    coroutine.resume(c)
end

function stopcoroutine(c)
    for k, v in ipairs(coroutines) do
        if c == v then
            table.remove(coroutines, k)
            break
        end
    end
end

function _coresolve()
    for k, co in ipairs(coroutines) do
        if coroutine.status(co) ~= "dead" then
            local _, msg = coroutine.resume(co)
            assert(msg == nil, msg)
        else
            stopcoroutine(co)
        end
    end
end

--- @param frames number
function waitframes(frames)
    local frame = 0
    while frame < frames do
        frame = frame + 1
        coroutine.yield()
    end
end

--- @param seconds number
function waitsecs(seconds)
    return waitframes(seconds * 60)
end