-- audio module: file_info example
-- this example script leverages audio.file_info,
-- before loading an audio file into softcut.

fileselect = require("fileselect")
fileselect.done = true

selected_file = "none"
selected_file_path = "none"

clip_info = {}
is_playing = false
play_position = 0
playback_rate = 1

screen_dirty = true

function init()
	-- softcut initialization:
	softcut.enable(1, 1)
	softcut.buffer(1, 1)
	softcut.level(1, 1.0)
	softcut.loop(1, 1)
	softcut.rate(1, 0)
	softcut.play(1, 1)
	softcut.fade_time(1, 0)

	softcut.phase_quant(1, 1 / 30)
	softcut.event_phase(update_positions)

	screen_redraw_metro = metro.init(function()
		if screen_dirty then
			redraw()
			screen_dirty = false
		end
	end, 1 / 60, -1)
	screen_redraw_metro:start()
end

function update_positions(i, pos)
	play_position = (pos - 1) / (clip_info.sample_length + 1)
	screen_dirty = true
end

function callback(file_path)
	if file_path ~= "cancel" then
		softcut.poll_stop_phase()
		clip_info = {}
		local channels, length, rate = audio.file_info(file_path)
		clip_info.sample_rate = rate
		if clip_info.sample_rate ~= 48000 then
			print("sample rate should be 48kHz!")
		end
		clip_info.sample_length = (length / clip_info.sample_rate) * calculate_samplerate_offset()
		softcut.buffer_clear()
		if channels == 2 then
			-- sum stereo to mono:
			for i = 1, 2 do
				softcut.buffer_read_mono(
					file_path, -- input file
					0, -- source start point, in seconds
					1, -- destination start point, in seconds
					clip_info.sample_length, -- duration
					i, -- soundfile channel to read
					1, -- buffer to write into
					i - 1, -- level of existing audio
					0.5 -- level of imported audio
				)
			end
		else
		  -- import mono
			softcut.buffer_read_mono(file_path, 0, 1, clip_info.sample_length)
		end
		-- set voice 1 rate to 0 (not playing)
		softcut.rate(1, 0)
		-- set voice 1 loop start to 1 second
		softcut.loop_start(1, 1.0)
		-- set voice 1 loop end to the sample's length
		softcut.loop_end(1, clip_info.sample_length + calculate_samplerate_offset())
		-- set voice 1 position to 1 second
		softcut.position(1, 1)
		
		is_playing = false
		playback_rate = 1
		play_position = 0
		screen_dirty = true
	end
end

function calculate_samplerate_offset()
	local sample_rate_compensation
	local import_sr = clip_info.sample_rate
	if (48000 / import_sr) > 1 then
		sample_rate_compensation = ((1200 * math.log(48000 / import_sr, 2)) / -100)
	else
		sample_rate_compensation = ((1200 * math.log(import_sr / 48000, 2)) / 100)
	end
	return math.pow(0.5, -sample_rate_compensation / 12)
end

function redraw()
	if fileselect.done or fileselect.done == nil then
		screen.clear()
		screen.level(15)
		screen.move(0,128)
		screen.text_right(playback_rate .. " (K1: playback rate)")
		screen.move(10, 20)
		screen.line_rel(play_position * 108, 0)
		screen.stroke()
		screen.move(0, 50)
		screen.text("press K2 to select file")
		if clip_info.sample_rate ~= nil then
			screen.move(0, 60)
			if not is_playing then
				screen.text("press K3 to play file")
			else
				screen.text("press K3 to stop file")
			end
		end
		screen.update()
	end
end

function key(n, z)
	if n == 2 and z == 1 then
		fileselect.enter(_path.audio, callback, "audio")
	elseif n == 3 and z == 1 and clip_info.sample_rate ~= nil then
		-- toggle voice 1 play state
		if is_playing then
			softcut.rate(1, 0)
			softcut.poll_stop_phase()
		else
			softcut.rate(1, playback_rate * calculate_samplerate_offset())
			softcut.poll_start_phase()
		end
		is_playing = not is_playing
		screen_dirty = true
	end
end

function enc(n, d)
  if n == 1 then
    if is_playing then
      playback_rate = playback_rate + d/100
      softcut.rate(1, playback_rate * calculate_samplerate_offset())
    end
  end
end