#include "uart_handler.h"
#include "protocol.h"

#include "driver/uart.h"
#include "esp_log.h"
#include "esp_timer.h"
#include "freertos/FreeRTOS.h"
#include "freertos/semphr.h"
#include "cJSON.h"

#include <string.h>
#include <stdlib.h>

static const char *TAG = "uart";
static SemaphoreHandle_t tx_mutex;

/* Pin assignments -- keep UART0 free for ESP-IDF console/logging */
#define UART_TX_PIN  GPIO_NUM_4
#define UART_RX_PIN  GPIO_NUM_5

void uart_handler_init(void)
{
    uart_config_t cfg = {
        .baud_rate  = PROTO_BAUD_RATE,
        .data_bits  = UART_DATA_8_BITS,
        .parity     = UART_PARITY_DISABLE,
        .stop_bits  = UART_STOP_BITS_1,
        .flow_ctrl  = UART_HW_FLOWCTRL_DISABLE,
        .source_clk = UART_SCLK_DEFAULT,
    };

    ESP_ERROR_CHECK(uart_param_config(PROTO_UART_NUM, &cfg));
    ESP_ERROR_CHECK(uart_set_pin(PROTO_UART_NUM, UART_TX_PIN, UART_RX_PIN,
                                 UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE));
    ESP_ERROR_CHECK(uart_driver_install(PROTO_UART_NUM,
                                        PROTO_RX_BUF_SIZE, PROTO_TX_BUF_SIZE,
                                        0, NULL, 0));

    tx_mutex = xSemaphoreCreateMutex();
    assert(tx_mutex);

    ESP_LOGI(TAG, "UART%d ready (TX=%d RX=%d @ %d baud)",
             PROTO_UART_NUM, UART_TX_PIN, UART_RX_PIN, PROTO_BAUD_RATE);
}

char *uart_read_line(void)
{
    static char buf[PROTO_MAX_LINE];
    int pos = 0;

    for (;;) {
        uint8_t byte;
        int n = uart_read_bytes(PROTO_UART_NUM, &byte, 1, portMAX_DELAY);
        if (n <= 0) {
            continue;
        }

        if (byte == '\n') {
            if (pos == 0) {
                continue;  /* skip empty lines */
            }
            buf[pos] = '\0';
            return strdup(buf);
        }

        if (byte == '\r') {
            continue;  /* ignore carriage returns */
        }

        if (pos < PROTO_MAX_LINE - 1) {
            buf[pos++] = (char)byte;
        } else {
            /* line too long -- discard and reset */
            ESP_LOGE(TAG, "line overflow (%d bytes), discarding", pos);
            pos = 0;
        }
    }
}

void uart_send_line(const char *json_line)
{
    if (!json_line) {
        return;
    }

    xSemaphoreTake(tx_mutex, portMAX_DELAY);

    size_t len = strlen(json_line);
    uart_write_bytes(PROTO_UART_NUM, json_line, len);
    uart_write_bytes(PROTO_UART_NUM, "\n", 1);

    xSemaphoreGive(tx_mutex);
}

void uart_send_response(const char *id, const char *status, cJSON *data)
{
    cJSON *root = cJSON_CreateObject();
    cJSON_AddStringToObject(root, "type", MSG_TYPE_RESP);
    cJSON_AddStringToObject(root, "id", id);
    cJSON_AddStringToObject(root, "status", status);

    if (data) {
        cJSON_AddItemToObject(root, "data", data);
    } else {
        cJSON_AddObjectToObject(root, "data");
    }

    char *out = cJSON_PrintUnformatted(root);
    uart_send_line(out);

    free(out);
    cJSON_Delete(root);
}

void uart_send_event(const char *event_name, cJSON *data)
{
    int64_t ts_ms = esp_timer_get_time() / 1000;

    cJSON *root = cJSON_CreateObject();
    cJSON_AddStringToObject(root, "type", MSG_TYPE_EVENT);
    cJSON_AddStringToObject(root, "event", event_name);

    if (data) {
        cJSON_AddItemToObject(root, "data", data);
    } else {
        cJSON_AddObjectToObject(root, "data");
    }

    cJSON_AddNumberToObject(root, "ts", (double)ts_ms);

    char *out = cJSON_PrintUnformatted(root);
    uart_send_line(out);

    free(out);
    cJSON_Delete(root);
}