#include "i2c_bus.h"

#include "esp_log.h"

static const char *TAG = "i2c";

static i2c_master_bus_handle_t s_bus;

esp_err_t i2c_bus_init(void)
{
    if (s_bus) {
        return ESP_OK;
    }

    i2c_master_bus_config_t cfg = {
        .i2c_port = I2C_NUM_0,
        .sda_io_num = I2C_BUS_SDA_GPIO,
        .scl_io_num = I2C_BUS_SCL_GPIO,
        .clk_source = I2C_CLK_SRC_DEFAULT,
        .glitch_ignore_cnt = 7,
        .flags.enable_internal_pullup = true,
    };

    esp_err_t err = i2c_new_master_bus(&cfg, &s_bus);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "bus init failed: %s", esp_err_to_name(err));
        return err;
    }

    ESP_LOGI(TAG, "bus up on SDA=%d SCL=%d @ %d Hz",
             I2C_BUS_SDA_GPIO, I2C_BUS_SCL_GPIO, I2C_BUS_FREQ_HZ);
    return ESP_OK;
}

esp_err_t i2c_bus_add_device(uint8_t addr, i2c_master_dev_handle_t *out)
{
    if (!s_bus) {
        return ESP_ERR_INVALID_STATE;
    }

    i2c_device_config_t cfg = {
        .dev_addr_length = I2C_ADDR_BIT_LEN_7,
        .device_address = addr,
        .scl_speed_hz = I2C_BUS_FREQ_HZ,
    };

    return i2c_master_bus_add_device(s_bus, &cfg, out);
}

int i2c_bus_scan(void)
{
    if (!s_bus) {
        ESP_LOGE(TAG, "scan before init");
        return -1;
    }

    int found = 0;
    ESP_LOGI(TAG, "scanning...");

    for (uint8_t addr = 0x08; addr < 0x78; addr++) {
        if (i2c_master_probe(s_bus, addr, 50) == ESP_OK) {
            const char *who = "?";
            if (addr == 0x21) {
                who = "PCF8574 expander";
            } else if (addr == 0x15) {
                who = "CST826 touch";
            }
            ESP_LOGI(TAG, "  0x%02X  %s", addr, who);
            found++;
        }
    }

    if (found == 0) {
        /* Loud, because this means the board or the pinout is wrong, and no
         * amount of display debugging past this point is worth doing. */
        ESP_LOGE(TAG, "no I2C devices found — check SDA=%d / SCL=%d wiring "
                      "before debugging anything else",
                 I2C_BUS_SDA_GPIO, I2C_BUS_SCL_GPIO);
    } else {
        ESP_LOGI(TAG, "scan done, %d device(s)", found);
    }

    return found;
}