Paradise/code/modules/instruments/songs/_song.dm

#define MUSICIAN_HEARCHECK_MINDELAY 4
#define MUSIC_MAXLINES 1000
#define MUSIC_MAXLINECHARS 300

/**
  * # Song datum
  *
  * These are the actual backend behind instruments.
  * They attach to an atom and provide the editor + playback functionality.
  */
/datum/song
	/// Name of the song
	var/name = "Untitled"

	/// The atom we're attached to/playing from
	var/atom/parent

	/// Our song lines
	var/list/lines

	/// delay between notes in deciseconds
	var/tempo = 5

	/// How far we can be heard
	var/instrument_range = 15

	/// Are we currently playing?
	var/playing = FALSE

	/// Are we currently editing?
	var/editing = TRUE
	/// Is the help screen open?
	var/help = FALSE

	/// Repeats left
	var/repeat = 0
	/// Maximum times we can repeat
	var/max_repeats = 10

	/// Our volume
	var/volume = 75
	/// Max volume
	var/max_volume = 75
	/// Min volume - This is so someone doesn't decide it's funny to set it to 0 and play invisible songs.
	var/min_volume = 1

	/// What instruments our built in picker can use. The picker won't show unless this is longer than one.
	var/list/allowed_instrument_ids

	//////////// Cached instrument variables /////////////
	/// Instrument we are currently using
	var/datum/instrument/using_instrument
	/// Cached legacy ext for legacy instruments
	var/cached_legacy_ext
	/// Cached legacy dir for legacy instruments
	var/cached_legacy_dir
	/// Cached list of samples, referenced directly from the instrument for synthesized instruments
	var/list/cached_samples
	/// Are we operating in legacy mode (so if the instrument is a legacy instrument)
	var/legacy = FALSE
	//////////////////////////////////////////////////////

	/////////////////// Playing variables ////////////////
	/**
	  * Build by compile_chords()
	  * Must be rebuilt on instrument switch.
	  * Compilation happens when we start playing and is cleared after we finish playing.
	  * Format: list of chord lists, with chordlists having (key1, key2, key3, tempodiv)
	  */
	var/list/compiled_chords
	/// Current section of a long chord we're on, so we don't need to make a billion chords, one for every unit ticklag.
	var/elapsed_delay
	/// Amount of delay to wait before playing the next chord
	var/delay_by
	/// Current chord we're on.
	var/current_chord
	/// Channel as text = current volume percentage but it's 0 to 100 instead of 0 to 1.
	var/list/channels_playing
	/// List of channels that aren't being used, as text. This is to prevent unnecessary freeing and reallocations from SSsounds/SSinstruments.
	var/list/channels_idle
	/// Person playing us
	var/mob/user_playing
	//////////////////////////////////////////////////////

	/// Last world.time we checked for who can hear us
	var/last_hearcheck = 0
	/// The list of mobs that can hear us
	var/list/hearing_mobs
	/// If this is enabled, some things won't be strictly cleared when they usually are (liked compiled_chords on play stop)
	var/debug_mode = FALSE
	/// Max sound channels to occupy
	var/max_sound_channels = CHANNELS_PER_INSTRUMENT
	/// Current channels, so we can save a length() call.
	var/using_sound_channels = 0
	/// Last channel to play. text.
	var/last_channel_played
	/// Should we not decay our last played note?
	var/full_sustain_held_note = TRUE

	/////////////////////// DO NOT TOUCH THESE ///////////////////
	var/octave_min = INSTRUMENT_MIN_OCTAVE
	var/octave_max = INSTRUMENT_MAX_OCTAVE
	var/key_min = INSTRUMENT_MIN_KEY
	var/key_max = INSTRUMENT_MAX_KEY
	var/static/list/note_offset_lookup
	var/static/list/accent_lookup
	//////////////////////////////////////////////////////////////

	///////////// !!FUN!! - Only works in synthesized mode! /////////////////
	/// Note numbers to shift.
	var/note_shift = 0
	var/note_shift_min = -100
	var/note_shift_max = 100
	var/can_noteshift = TRUE
	/// The kind of sustain we're using
	var/sustain_mode = SUSTAIN_LINEAR
	/// When a note is considered dead if it is below this in volume
	var/sustain_dropoff_volume = INSTRUMENT_MIN_SUSTAIN_DROPOFF
	/// Total duration of linear sustain for 100 volume note to get to SUSTAIN_DROPOFF
	var/sustain_linear_duration = 5
	/// Exponential sustain dropoff rate per decisecond
	var/sustain_exponential_dropoff = 1.4
	////////// DO NOT DIRECTLY SET THESE!
	/// Do not directly set, use update_sustain()
	var/cached_linear_dropoff = 10
	/// Do not directly set, use update_sustain()
	var/cached_exponential_dropoff = 1.045
	/////////////////////////////////////////////////////////////////////////

	var/static/list/valid_files[0] // Cache to avoid running fexists() every time

/datum/song/New(atom/parent, list/instrument_ids, new_range)
	SSinstruments.on_song_new(src)
	lines = list()
	tempo = sanitize_tempo(tempo)
	src.parent = parent
	if(instrument_ids)
		allowed_instrument_ids = islist(instrument_ids) ? instrument_ids : list(instrument_ids)
	if(length(allowed_instrument_ids))
		set_instrument(allowed_instrument_ids[1])
	hearing_mobs = list()
	volume = clamp(volume, min_volume, max_volume)
	channels_playing = list()
	channels_idle = list()
	if(!note_offset_lookup)
		note_offset_lookup = list(9, 11, 0, 2, 4, 5, 7)
		accent_lookup = list("b" = -1, "s" = 1, "#" = 1, "n" = 0)
	update_sustain()
	if(new_range)
		instrument_range = new_range

/datum/song/Destroy()
	stop_playing()
	SSinstruments.on_song_del(src)
	lines = null
	using_instrument.songs_using -= src
	using_instrument = null
	allowed_instrument_ids = null
	parent = null
	return ..()

/**
  * Checks and stores which mobs can hear us. Terminates sounds for mobs that leave our range.
  */
/datum/song/proc/do_hearcheck()
	last_hearcheck = world.time
	var/list/old = hearing_mobs.Copy()
	hearing_mobs.len = 0
	var/turf/source = get_turf(parent)
	for(var/mob/M in GLOB.player_list)
		if(M.z != source.z) // Z-level check
			continue
		var/dist = get_dist(M, source)
		if(dist > instrument_range) // Distance check
			continue
		if(!isInSight(M, source)) // Visibility check (direct line of sight)
			continue
		hearing_mobs[M] = dist
	var/list/exited = old - hearing_mobs
	for(var/i in exited)
		terminate_sound_mob(i)

/**
  * Sets our instrument, caching anything necessary for faster accessing. Accepts an ID, typepath, or instantiated instrument datum.
  */
/datum/song/proc/set_instrument(datum/instrument/I)
	terminate_all_sounds()
	var/old_legacy
	if(using_instrument)
		using_instrument.songs_using -= src
		old_legacy = (using_instrument.instrument_flags & INSTRUMENT_LEGACY)
	using_instrument = null
	cached_samples = null
	cached_legacy_ext = null
	cached_legacy_dir = null
	legacy = null
	if(istext(I) || ispath(I))
		I = SSinstruments.instrument_data[I]
	if(istype(I))
		using_instrument = I
		I.songs_using += src
		var/instrument_legacy = (I.instrument_flags & INSTRUMENT_LEGACY)
		if(instrument_legacy)
			cached_legacy_ext = I.legacy_instrument_ext
			cached_legacy_dir = I.legacy_instrument_path
			legacy = TRUE
		else
			cached_samples = I.samples
			legacy = FALSE
		if(isnull(old_legacy) || (old_legacy != instrument_legacy))
			if(playing)
				compile_chords()

/**
  * Attempts to start playing our song.
  */
/datum/song/proc/start_playing(mob/user)
	if(playing)
		return
	if(!using_instrument?.is_ready())
		to_chat(user, "<span class='warning'>An error has occurred with [src]. Please reset the instrument.</span>")
		return
	compile_chords()
	if(!length(compiled_chords))
		to_chat(user, "<span class='warning'>Song is empty.</span>")
		return
	playing = TRUE
	SStgui.update_uis(parent)
	//we can not afford to runtime, since we are going to be doing sound channel reservations and if we runtime it means we have a channel allocation leak.
	//wrap the rest of the stuff to ensure stop_playing() is called.
	do_hearcheck()
	SEND_SIGNAL(parent, COMSIG_SONG_START)
	elapsed_delay = 0
	delay_by = 0
	current_chord = 1
	user_playing = user
	START_PROCESSING(SSinstruments, src)

/**
  * Stops playing, terminating all sounds if in synthesized mode. Clears hearing_mobs.
  */
/datum/song/proc/stop_playing()
	if(!playing)
		return
	playing = FALSE
	if(!debug_mode)
		compiled_chords = null
	STOP_PROCESSING(SSinstruments, src)
	SEND_SIGNAL(parent, COMSIG_SONG_END)
	terminate_all_sounds(TRUE)
	hearing_mobs.len = 0
	SStgui.update_uis(parent)
	user_playing = null

/**
  * Processes our song.
  */
/datum/song/proc/process_song(wait)
	if(!length(compiled_chords) || should_stop_playing(user_playing))
		stop_playing()
		return
	if(++elapsed_delay >= delay_by)
		// We were sustaining the final note but not anymore
		if(current_chord > length(compiled_chords))
			if(repeat)
				repeat--
				current_chord = 1
				SStgui.update_uis(parent)
				return
			else
				stop_playing()
				return
		var/list/chord = compiled_chords[current_chord]
		play_chord(chord)
		elapsed_delay = 0
		delay_by = tempodiv_to_delay(chord[length(chord)])
		current_chord++

/**
  * Converts a tempodiv to ticks to elapse before playing the next chord, taking into account our tempo.
  */
/datum/song/proc/tempodiv_to_delay(tempodiv)
	tempodiv = tempodiv || world.tick_lag // Default to world.tick_lag in case someone's trying to be smart
	return max(1, round((tempo / tempodiv) / world.tick_lag, 1))

/**
  * Compiles chords.
  */
/datum/song/proc/compile_chords()
	legacy ? compile_legacy() : compile_synthesized()
	// Some chords may be null for some reason - exclude them.
	listclearnulls(compiled_chords)

/**
  * Plays a chord.
  */
/datum/song/proc/play_chord(list/chord)
	// last value is timing information
	for(var/i in 1 to (length(chord) - 1))
		legacy? playkey_legacy(chord[i][1], chord[i][2], chord[i][3], user_playing) : playkey_synth(chord[i], user_playing)

/**
  * Checks if we should halt playback.
  */
/datum/song/proc/should_stop_playing(mob/user)
	return QDELETED(parent) || !using_instrument || !playing

/**
  * Sanitizes tempo to a value that makes sense and fits the current world.tick_lag.
  */
/datum/song/proc/sanitize_tempo(new_tempo)
	new_tempo = abs(new_tempo)
	return clamp(round(new_tempo, world.tick_lag), world.tick_lag, 5 SECONDS)

/**
  * Gets our beats per minute based on our tempo.
  */
/datum/song/proc/get_bpm()
	return 600 / tempo

/**
  * Sets our tempo from a beats-per-minute, sanitizing it to a valid number first.
  */
/datum/song/proc/set_bpm(bpm)
	tempo = sanitize_tempo(600 / bpm)

/datum/song/process(wait)
	if(!playing)
		return PROCESS_KILL
	// it's expected this ticks at every world.tick_lag. if it lags, do not attempt to catch up.
	process_song(world.tick_lag)
	process_decay(world.tick_lag)

/**
  * Updates our cached linear/exponential falloff stuff, saving calculations down the line.
  */
/datum/song/proc/update_sustain()
	// Exponential is easy
	cached_exponential_dropoff = sustain_exponential_dropoff
	// Linear, not so much, since it's a target duration from 100 volume rather than an exponential rate.
	var/target_duration = sustain_linear_duration
	var/volume_diff = max(0, 100 - sustain_dropoff_volume)
	var/volume_decrease_per_decisecond = volume_diff / target_duration
	cached_linear_dropoff = volume_decrease_per_decisecond

/**
  * Setter for setting output volume.
  */
/datum/song/proc/set_volume(volume)
	src.volume = clamp(volume, max(0, min_volume), min(100, max_volume))
	update_sustain()
	// We don't want to send the whole payload (song included) just for volume
	var/datum/tgui/ui = SStgui.get_open_ui(usr, parent, "main")
	if(ui)
		ui.send_update(list("volume" = volume), TRUE)

/**
  * Setter for setting how low the volume has to get before a note is considered "dead" and dropped
  */
/datum/song/proc/set_dropoff_volume(volume, no_refresh = FALSE)
	sustain_dropoff_volume = clamp(volume, INSTRUMENT_MIN_SUSTAIN_DROPOFF, 100)
	update_sustain()
	if(!no_refresh)
		SStgui.update_uis(parent)

/**
  * Setter for setting exponential falloff factor.
  */
/datum/song/proc/set_exponential_drop_rate(drop, no_refresh = FALSE)
	sustain_exponential_dropoff = clamp(drop, INSTRUMENT_EXP_FALLOFF_MIN, INSTRUMENT_EXP_FALLOFF_MAX)
	update_sustain()
	if(!no_refresh)
		SStgui.update_uis(parent)

/**
  * Setter for setting linear falloff duration.
  */
/datum/song/proc/set_linear_falloff_duration(duration, no_refresh = FALSE)
	sustain_linear_duration = clamp(duration, 0.1, INSTRUMENT_MAX_TOTAL_SUSTAIN)
	update_sustain()
	if(!no_refresh)
		SStgui.update_uis(parent)

/datum/song/vv_edit_var(var_name, var_value)
	. = ..()
	if(.)
		switch(var_name)
			if(NAMEOF(src, volume))
				set_volume(var_value)
			if(NAMEOF(src, sustain_dropoff_volume))
				set_dropoff_volume(var_value)
			if(NAMEOF(src, sustain_exponential_dropoff))
				set_exponential_drop_rate(var_value)
			if(NAMEOF(src, sustain_linear_duration))
				set_linear_falloff_duration(var_value)

// subtype for handheld instruments, like violin
/datum/song/handheld

/datum/song/handheld/should_stop_playing(mob/user)
	. = ..()
	if(.)
		return TRUE
	var/obj/item/instrument/I = parent
	return I.should_stop_playing(user)

// subtype for stationary structures, like pianos
/datum/song/stationary

/datum/song/stationary/should_stop_playing(mob/user)
	. = ..()
	if(.)
		return TRUE
	var/obj/structure/musician/M = parent
	return M.should_stop_playing(user)

// subtype for thermal drills
/datum/song/thermal_drill

/datum/song/thermal_drill/should_stop_playing(mob/user)
	. = ..()
	if(.)
		return TRUE
	var/obj/item/thermal_drill/D = parent
	return D.should_stop_playing(user)