#include "speaker.h"
#include "state_tracking.h"

static const char *TAG = "speaker";

static size_t audio_block_size = 4096;

typedef struct {
    /// The path to the file being played.
    char* file_name;
	/// The handle to the file being played.
	FILE* file_handle;
    /// A number that all samples will be shifted right by.
    uint8_t prescaler;
    /// A flag for repeating.
    bool repeat;
} playing_audio_clip_t;

// It's hard to get the tx_chan's internal state, so instead, we keep track of it here.
bool channel_enabled = false;
i2s_chan_handle_t tx_chan;

/// A queue of owned `char*` to be stopped from playing.
/// 
/// the speaker driver system will free the given char* when it is done with it.
QueueHandle_t stop_clip_queue;
/// A queue of `audio_clip_t`s to be played once there is nothing being played
QueueHandle_t play_clip_queue;

/// The clips that are currently playing
std::vector<playing_audio_clip_t> playing_clips;

static bool push_clip(audio_clip_t clip) {
	ESP_LOGD(TAG, "playing %s", clip.file_name);
	FILE* fh = fopen(clip.file_name, "rb");
	if (fh == NULL) {
		ESP_LOGW(TAG, "failed to open %s", clip.file_name);
		return false;
	} else {
		// skip the .wav header
		fseek(fh, 44, SEEK_SET);

		playing_audio_clip_t playing_clip = {
			.file_name = clip.file_name,
			.file_handle = fh,
			.prescaler = clip.prescaler,
			.repeat = clip.repeat,
		};
		playing_clips.push_back(playing_clip);
		return true;
	}
}

/// @brief Disables the channel if neccesary.
static void disable_channel() {
	if (channel_enabled) {
		ESP_ERROR_CHECK_WITHOUT_ABORT(i2s_channel_disable(tx_chan));
		channel_enabled = false;
	}
}
/// @brief Enables the channel if neccesary
static void enable_channel() {
	if (!channel_enabled) {
		ESP_ERROR_CHECK_WITHOUT_ABORT(i2s_channel_enable(tx_chan));
		channel_enabled = true;
	}
}

static void speaker_task(void* arg) {
	audio_clip_t next_clip;
	char* clip_to_stop;

	int16_t* audio_buf = (int16_t*) malloc(audio_block_size * sizeof(int16_t));
	int16_t* file_buf = (int16_t*) malloc(audio_block_size * sizeof(int16_t));

	while (1) {
		// first, take all "play immediatly" clips from the queue.
		while (xQueuePeek(play_clip_queue, &next_clip, 0) == pdTRUE && next_clip.play_immediatly) {
			if (xQueueReceive(play_clip_queue, &next_clip, 0) == pdTRUE) {
				push_clip(next_clip);
			}
		}

		// handle any stop requests
		while (xQueueReceive(stop_clip_queue, &clip_to_stop, 0) == pdTRUE) {
			// delete clip from list
			bool found = false;
			for (int clip_idx = playing_clips.size()-1; clip_idx >= 0; clip_idx--) {
				playing_audio_clip_t& clip = playing_clips.at(clip_idx);
				if (strcmp(clip.file_name, clip_to_stop) == 0) {
					found = true;
					ESP_LOGV(TAG, "stopping %s", clip.file_name);
					fclose(clip.file_handle);
					free(clip.file_name);
					playing_clips.erase(playing_clips.begin() + clip_idx);
				}
			}
			if (!found) {
				ESP_LOGW(TAG, "Could not find clip \"%s\" to stop", clip_to_stop);
			}
			// free the string that was passed into the queue
			free(clip_to_stop);
		}

		// if we aren't playing any clips, wait for the next one.
		if (playing_clips.empty()) {
			if (xQueueReceive(play_clip_queue, &next_clip, 0) == pdTRUE) {
				push_clip(next_clip);
			} else {
				// we must wait before our next clip
				disable_channel();
				// now wait for next clip
				if (xQueueReceive(play_clip_queue, &next_clip, portMAX_DELAY) == pdTRUE) {
					push_clip(next_clip);
				}
			}
		}

		// send 1 block
		std::memset(audio_buf, 0, audio_block_size * sizeof(int16_t));

		for (int clip_idx = playing_clips.size()-1; clip_idx >= 0; clip_idx--) {
			playing_audio_clip_t& clip = playing_clips.at(clip_idx);

			size_t samples_read = fread(file_buf, sizeof(uint16_t), audio_block_size, clip.file_handle);
			if (samples_read == 0) {
				if (clip.repeat) {
					ESP_LOGV(TAG, "repeating %s", clip.file_name);
					fseek(clip.file_handle, 44, SEEK_SET);
				} else {
					ESP_LOGV(TAG, "finishing %s", clip.file_name);
					fclose(clip.file_handle);
					free(clip.file_name);
					playing_clips.erase(playing_clips.begin() + clip_idx);
				}
				continue;
			}

			for (int i = 0; i < samples_read; i++) {
				audio_buf[i] += (file_buf[i] >> clip.prescaler);
			}
		}

		size_t bytes_to_write = audio_block_size * sizeof(int16_t);
		size_t bytes_written;
		if (!channel_enabled) {
			ESP_ERROR_CHECK_WITHOUT_ABORT(i2s_channel_preload_data(tx_chan, audio_buf, bytes_to_write, &bytes_written));
			enable_channel();
		} else {
			ESP_ERROR_CHECK_WITHOUT_ABORT(i2s_channel_write(tx_chan, audio_buf, bytes_to_write, &bytes_written, portMAX_DELAY));
		}
		if (bytes_written != bytes_to_write) {
			ESP_LOGW(TAG, "only %d bytes written to the i2s channel! (expected %d)", bytes_written, bytes_to_write);
		}
	}

    vTaskDelete(NULL);
}

bool play_clip_wav(const char* file_name, bool play_immediately, bool repeat, uint8_t prescaler, TickType_t ticks_to_wait) {
	// clone the passed in string to the heap.
	size_t len = strlen(file_name);
	char* dynamic_file_name = (char*) malloc(len+1);
	strcpy(dynamic_file_name, file_name);

	audio_clip_t clip = {
		.file_name = dynamic_file_name,
		.prescaler = prescaler,
		.repeat = repeat,
		.play_immediatly = play_immediately,
	};

	if (is_state_tracking()) {
		char buf[64];
		sprintf(buf, "%s:%d:%d:%d", file_name, play_immediately, repeat, prescaler);
		event_occured("PLAY_WAV", buf);
	}

	if (play_immediately) {
		return xQueueSendToFront(play_clip_queue, &clip, ticks_to_wait) == pdTRUE;
	}
	return xQueueSend(play_clip_queue, &clip, ticks_to_wait) == pdTRUE;
}

bool stop_clip(const char* file_name, TickType_t ticks_to_wait) {
	// clone the passed in string to the heap.
	size_t len = strlen(file_name);
	char* dynamic_file_name = (char*) malloc(len+1);
	strcpy(dynamic_file_name, file_name);

	if (is_state_tracking()) {
		event_occured("STOP_WAV", file_name);
	}

	return xQueueSend(stop_clip_queue, &dynamic_file_name, ticks_to_wait) == pdTRUE;
}

void init_speaker(void) {
	ESP_LOGI(TAG, "Initializing speaker...");

	i2s_chan_config_t tx_chan_cfg = I2S_CHANNEL_DEFAULT_CONFIG(I2S_NUM_AUTO, I2S_ROLE_MASTER);
	ESP_ERROR_CHECK(i2s_new_channel(&tx_chan_cfg, &tx_chan, NULL));

	i2s_std_config_t tx_std_cfg = {
		.clk_cfg  = I2S_STD_CLK_DEFAULT_CONFIG(SAMPLE_RATE),
		.slot_cfg = I2S_STD_MSB_SLOT_DEFAULT_CONFIG(I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_MONO),
		.gpio_cfg = {
			.mclk = I2S_GPIO_UNUSED,
			.bclk = SPEAKER_PIN_BCLK,
			.ws   = SPEAKER_PIN_WS,
			.dout = SPEAKER_PIN_DOUT,
			.din  = GPIO_NUM_NC,
			.invert_flags = {
				.mclk_inv = false,
				.bclk_inv = false,
				.ws_inv   = false,
			},
		},
	};
	ESP_ERROR_CHECK(i2s_channel_init_std_mode(tx_chan, &tx_std_cfg));

	i2s_chan_info_t info = {};
	i2s_channel_get_info(tx_chan, &info);
	if (info.total_dma_buf_size != 0) {
		audio_block_size = info.total_dma_buf_size / sizeof(int16_t);
	}

	// init queues
	play_clip_queue = xQueueCreate(CLIP_QUEUE_SIZE, sizeof(audio_clip_t));
	stop_clip_queue = xQueueCreate(CLIP_QUEUE_SIZE, sizeof(char*));

	// start task
    xTaskCreate(speaker_task, "play_audio", 4096, NULL, 5, NULL);

	play_clip_wav(MOUNT_POINT "/startup.wav", true, false, 4, 0);
	
	ESP_LOGI(TAG, "Speaker initialized!");
}