#include <stdio.h>
#include <math.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/i2s_std.h"

#define SAMPLE_RATE     48000
#define PI              3.14159265
#define TABLE_SIZE      (SAMPLE_RATE / 440)  // 440 Hz
#define AMPLITUDE       3000

static i2s_chan_handle_t tx_chan;  // TX-Kanal

extern "C" void app_main(void)
{
    // Kanal anlegen
    i2s_chan_config_t chan_cfg = I2S_CHANNEL_DEFAULT_CONFIG(I2S_NUM_0, I2S_ROLE_MASTER);
    ESP_ERROR_CHECK(i2s_new_channel(&chan_cfg, &tx_chan, NULL));

    // Standard-Konfiguration
    i2s_std_config_t std_cfg = {
        .clk_cfg = {
            .sample_rate_hz = SAMPLE_RATE,
            .clk_src = I2S_CLK_SRC_DEFAULT,
            .mclk_multiple = I2S_MCLK_MULTIPLE_256,
        },
        .slot_cfg = {
            .data_bit_width = I2S_DATA_BIT_WIDTH_16BIT,
            .slot_bit_width = I2S_SLOT_BIT_WIDTH_16BIT,
            .slot_mode = I2S_SLOT_MODE_STEREO,
            .slot_mask = I2S_STD_SLOT_BOTH,
            .ws_width = I2S_DATA_BIT_WIDTH_16BIT,
            .ws_pol = false,
            .bit_shift = false,
            .msb_right = false,
        },
        .gpio_cfg = {
            .mclk = I2S_GPIO_UNUSED,  // MCLK nicht genutzt
            .bclk = GPIO_NUM_5,
            .ws   = GPIO_NUM_25,
            .dout = GPIO_NUM_26,
            .din  = I2S_GPIO_UNUSED,
            .invert_flags = {
                .mclk_inv = false,
                .bclk_inv = false,
                .ws_inv   = false
            }
        }
    };

    // Init & Enable
    ESP_ERROR_CHECK(i2s_channel_init_std_mode(tx_chan, &std_cfg));
    ESP_ERROR_CHECK(i2s_channel_enable(tx_chan));

    // Sinustabelle vorbereiten
    int16_t sine_table[TABLE_SIZE * 2]; // Stereo
    for (int i = 0; i < TABLE_SIZE; i++) {
        float phase = 2.0f * PI * i / TABLE_SIZE;
        int16_t sample = (int16_t)(AMPLITUDE * sinf(phase));

        sine_table[2 * i + 0] = sample; // links
        sine_table[2 * i + 1] = sample; // rechts
    }

    printf("🔊 Sinusausgabe startet...\n");

    // Endlosschleife
    while (true) {
        size_t bytes_written = 0;
        ESP_ERROR_CHECK(i2s_channel_write(tx_chan, sine_table, sizeof(sine_table), &bytes_written, portMAX_DELAY));
    }
}