#include <stdint.h>
#include <string.h>
#include <stdio.h>

#include <espressif/esp_common.h>
#include <FreeRTOS.h>
#include <task.h>
#include <httpd/httpd.h>

#include "common.h"

#define LED_PIN 2

enum {
    SSI_UPTIME,
    SSI_FREE_HEAP,
    SSI_LED_STATE
};

int32_t ssi_handler(int32_t iIndex, char *pcInsert, int32_t iInsertLen) {
    switch (iIndex) {
    case SSI_UPTIME:
        snprintf(pcInsert, iInsertLen, "%d",
                 xTaskGetTickCount() * portTICK_PERIOD_MS / 1000);
        break;
    case SSI_FREE_HEAP:
        snprintf(pcInsert, iInsertLen, "%d", (int) xPortGetFreeHeapSize());
        break;
    case SSI_LED_STATE:
        snprintf(pcInsert, iInsertLen, (GPIO.OUT & BIT(LED_PIN)) ? "Off" : "On");
        break;
    default:
        snprintf(pcInsert, iInsertLen, "N/A");
        break;
    }

    /* Tell the server how many characters to insert */
    return (strlen(pcInsert));
}

char *gpio_cgi_handler(int iIndex, int iNumParams, char *pcParam[], char *pcValue[]) {
    for (int i = 0; i < iNumParams; i++) {
        if (strcmp(pcParam[i], "on") == 0) {
            uint8_t gpio_num = atoi(pcValue[i]);
            gpio_enable(gpio_num, GPIO_OUTPUT);
            gpio_write(gpio_num, true);
        } else if (strcmp(pcParam[i], "off") == 0) {
            uint8_t gpio_num = atoi(pcValue[i]);
            gpio_enable(gpio_num, GPIO_OUTPUT);
            gpio_write(gpio_num, false);
        } else if (strcmp(pcParam[i], "toggle") == 0) {
            uint8_t gpio_num = atoi(pcValue[i]);
            gpio_enable(gpio_num, GPIO_OUTPUT);
            gpio_toggle(gpio_num);
        }
    }
    return "/index.ssi";
}

char *about_cgi_handler(int iIndex, int iNumParams, char *pcParam[], char *pcValue[]) {
    return "/about.html";
}

char *websocket_cgi_handler(int iIndex, int iNumParams, char *pcParam[], char *pcValue[]) {
    return "/websockets.html";
}

void websocket_task(void *pvParameter) {
    struct tcp_pcb *pcb = (struct tcp_pcb *) pvParameter;

    printf("Websocket process started\n");
    for (;;) {
        if (pcb == NULL || pcb->state != ESTABLISHED) {
            printf("Connection closed, deleting task\n");
            break;
        }

        int uptime = xTaskGetTickCount() * portTICK_PERIOD_MS / 1000;
        int heap = (int) xPortGetFreeHeapSize();
        int led = !gpio_read(LED_PIN);

        /* Generate response in JSON format */
        char response[64];
        int len = snprintf(response, sizeof (response),
                           "{\"uptime\" : \"%d\","
                           " \"heap\" : \"%d\","
                           " \"led\" : \"%d\"}", uptime, heap, led);
        if (len < sizeof (response))
            websocket_write(pcb, (unsigned char *) response, len, WS_TEXT_MODE);

        vTaskDelay(2000 / portTICK_PERIOD_MS);
    }

    printf("Websocket process shutting down\n");
    vTaskDelete(NULL);
}

/**
 * This function is called when websocket frame is received.
 *
 * Note: this function is executed on TCP thread and should return as soon
 * as possible.
 */
void websocket_cb(struct tcp_pcb *pcb, uint8_t *data, u16_t data_len, uint8_t mode) {
    printf("[websocket_callback]:\n%.*s\n", (int) data_len, (char*) data);

    uint8_t response[2];
    uint16_t val;

    switch (data[0]) {
    case 'A': // ADC
        /* This should be done on a separate thread in 'real' applications */
        val = sdk_system_adc_read();
        break;
    case 'D': // Disable LED
        gpio_write(LED_PIN, true);
        val = 0xDEAD;
        break;
    case 'E': // Enable LED
        gpio_write(LED_PIN, false);
        val = 0xBEEF;
        break;
    default:
        printf("Unknown command\n");
        val = 0;
        break;
    }

    response[1] = (uint8_t) val;
    response[0] = val >> 8;

    websocket_write(pcb, response, 2, WS_BIN_MODE);
}

/**
 * This function is called when new websocket is open and
 * creates a new websocket_task if requested URI equals '/stream'.
 */
void websocket_open_cb(struct tcp_pcb *pcb, const char *uri) {
    printf("WS URI: %s\n", uri);
    if (!strcmp(uri, "/stream")) {
        printf("request for streaming\n");
        xTaskCreate(&websocket_task, "websocket_task", 256, (void *) pcb, 2, NULL);
    }
}

void httpd_task(void *pvParameters) {
    tCGI pCGIs[] = {
        {"/gpio", (tCGIHandler) gpio_cgi_handler},
        {"/about", (tCGIHandler) about_cgi_handler},
        {"/websockets", (tCGIHandler) websocket_cgi_handler},
    };

    const char *pcConfigSSITags[] = {
        "uptime", // SSI_UPTIME
        "heap",   // SSI_FREE_HEAP
        "led"     // SSI_LED_STATE
    };

    printf("httpd process started\n");

    /* register handlers and start the server */
    http_set_cgi_handlers(pCGIs, sizeof (pCGIs) / sizeof (pCGIs[0]));
    http_set_ssi_handler((tSSIHandler) ssi_handler, pcConfigSSITags,
                         sizeof (pcConfigSSITags) / sizeof (pcConfigSSITags[0]));
    websocket_register_callbacks((tWsOpenHandler) websocket_open_cb,
                                 (tWsHandler) websocket_cb);
    printf("Entering httpd main loop\n");
    httpd_init();
    printf("httpd exiting\n");

    for (;;)
        vTaskDelay(2000 / portTICK_PERIOD_MS);
}