local M = {}

function M:peek(job)
	local start, cache = os.clock(), ya.file_cache(job)
	if not cache or self:preload() ~= 1 then
		return
	end	
	ya.sleep(math.max(0, 0.1 + start - os.clock()))
	ya.image_show(cache, job.area)
	ya.preview_widgets(job, {})
end


function M:seek(job, units)
	local h = cx.active.current.hovered
	if h and h.url == job.file.url then
		local step = ya.clamp(-1, units, 1)
		ya.manager_emit("peek", { math.max(0, cx.active.preview.skip + step), only_if = job.file.url })
	end
end

function M:preload(job)
    ya.dbg("Preloading audio-preview ***")
	if not job then
		return 1
	end
	
	local percentage = 5 + job.skip
	if percentage > 95 then
		ya.manager_emit("peek", { 90, only_if = job.file.url, upper_bound = true })
		return 2
	end
	local cache = ya.file_cache(job)
	if not cache then
		return 1
	end

	local cha = fs.cha(cache)
	if cha and cha.len > 0 then
		return 1
	end

    -- generate image
	ya.err("Calling sox for: " .. tostring(job.file.url) .. ", cache: " .. tostring(cache))
	local child, code = Command("sox")
		:arg({tostring(job.file.url),
		     "-n", "trim", "0:00", "1:00",
		     "remix", "1",
		     "rate", "12k",
		     "spectrogram",
		     "-o", tostring(cache)})
		:spawn()

	if not child then
		ya.err("spawn `sox` command returns " .. tostring(code))
		return 0
	end

	local status = child:wait()
	return status and status.success and 1 or 2
end

return M