potion_party_leds/main/server.h

///
//
// server.h
// Call server_init() to start up an http webserver.
// listens on '/' for GET queries with a url query format like
// ?l=*&r0=*&g0=*&b0=*&a0=*&t0=* ... &rl=*&gl=*&bl=*&al=*&tl=*
// Where l is the number of points on a gradient. And each point of the gradient has a r* g* b* a* and t* where * is the index.
// r g and b are the red green and blue 8-bit colour components of a point on the gradient. A is the 5-bit global component of the led at that point.
// t is the offset from the start measured in leds.
// Each point also has an optional &m argument for movement. &m should be either -1, +1 or 0 and represents the movement per frame or the point.
// &m arguments are only valid if the global &d variable is also defined.
// So if &d is defined (say, &d=3) a point on the gradient will have &r, &g, &b, &a, &t, and &m. And the global variables will be &l and &d
//
///

#ifndef _potion_party_server_h
#define _potion_party_server_h

#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include "shared.h"
#include "leds.h"
#include "esp_http_server.h"
#include "esp_system.h"
#include "esp_netif.h"
#include "sys_arch.h"

static
httpd_handle_t g_http_server = NULL;

struct parse_error_t {
    const char* error;
};

// Parse a gradient query
static
struct parse_error_t parse_leds_query(char* query_string, size_t query_size) {
    char query_value[16];
    char query_key[3];
    struct gradient_t gradient;

    // Fetch the &l length parameter.
    // Interpret as a positive integer number of points on the gradient.
    if(httpd_query_key_value(query_string, "l", query_value, sizeof(query_value)) == ESP_OK) {
        gradient.points_len = max(0, atoi(query_value));
    } else {
        leds_set_current_gradient(&g_default_gradient, 0);
        return (struct parse_error_t) {
            .error = "ERROR: Failed to find length parameter &l"
        };
    }

    // Get the &d 'duration' parameter from the query.
    // Interpreted as a floating point number of seconds before returning to default state.
    if(httpd_query_key_value(query_string, "d", query_value, sizeof(query_value)) == ESP_OK) {
        gradient.duration = atof(query_string);
    } else {
        gradient.duration = 0;
    }

    LOGLN("Reading %zu points of gradient query:", gradient.points_len);
    LOGLN("duration: %f", gradient.duration);

    // Get the gradient point components for every point that was promised by the &l parameter
    for(int point = 0; point < gradient.points_len; ++point) {
        // Get the r, g, and b components as 8 bit integers
        sprintf(query_key, "r%d", point);
        if(httpd_query_key_value(query_string, query_key, query_value, sizeof(query_size)) == ESP_OK) {
            gradient.points[point].led.components.red = atoi(query_value);
        } else {
            return (struct parse_error_t) {
                .error = "ERROR: Point missing red component &r."
            };
        }
        sprintf(query_key, "g%d", point);
        if(httpd_query_key_value(query_string, query_key, query_value, sizeof(query_size)) == ESP_OK) {
            gradient.points[point].led.components.green = atoi(query_value);
        } else {
            return (struct parse_error_t) {
                .error = "ERROR: Point missing green component &g."
            };
        }
        sprintf(query_key, "b%d", point);
        if(httpd_query_key_value(query_string, query_key, query_value, sizeof(query_value)) == ESP_OK) {
            gradient.points[point].led.components.blue = atoi(query_value);
        } else {
            return (struct parse_error_t) {
                .error = "ERROR: Point missing blue component &b."
            };
        }
        // Get the global variable, passed as alpha. Limited to 0-32 (a 5bit unsigned int)
        // Make sure the most significant 3 bits are all ones
        sprintf(query_key, "a%d", point);
        if(httpd_query_key_value(query_string, query_key, query_value, sizeof(query_value)) == ESP_OK) {
            gradient.points[point].led.components.global = GLOBAL((uint8_t)atoi(query_value));
        } else {
            return (struct parse_error_t) {
                .error = "ERROR: Point missing alpha component &a."
            };
        }
        // Get the time of the gradient as a number ranging from 0 - 60.
        // Interpreted as an integer offset from the first led to the last
        sprintf(query_key, "t%d", point);
        if(httpd_query_key_value(query_string, query_key, query_value, sizeof(query_value)) == ESP_OK) {
            gradient.points[point].offset = clamp(0, 60, atoi(query_value));
        } else {
            return (struct parse_error_t) {
                .error = "ERROR: Point missing time component &t."
            };
        }
        // Get the movement variable &m.
        // Interpreted as an integer number from -1 to +1
        sprintf(query_key, "m%d", point);
        if(gradient.duration > 0 && httpd_query_key_value(query_string, query_key, query_value, sizeof(query_value)) == ESP_OK) {
            gradient.points[point].movement = clamp(-1, +1, atoi(query_value));
        } else {
            gradient.points[point].movement = 0;
        }

        // Log fetched fields
        LOGLN("led[%d]:", point);
        LOGLN("    r %d", gradient.points[point].led.components.red);
        LOGLN("    g %d", gradient.points[point].led.components.green);
        LOGLN("    b %d", gradient.points[point].led.components.blue);
        LOGLN("    global %d", gradient.points[point].led.components.global >> 3);
        LOGLN("    t %zu", gradient.points[point].offset);
    }

    leds_set_current_gradient(&gradient, 0);
    return (struct parse_error_t) { .error = NULL };
}

// receives HTTP GET requests on root
static 
esp_err_t on_http_get_root(httpd_req_t* request) {
    // Error mewsages for cases of good and bad
    static const char* response_ok = "OK!";

    const char* response_msg = response_ok;

    LOGLN("POST received on '/'.");

    // buffer for query string
    char* query_buffer;
    size_t query_length = httpd_req_get_url_query_len(request) + 1;
    struct parse_error_t result = { .error = NULL };

    if(query_length > 1) {
        query_buffer = malloc(query_length * sizeof(char));
        if(httpd_req_get_url_query_str(request, query_buffer, query_length) == ESP_OK) {
            LOGLN("Received query.");
            result = parse_leds_query(query_buffer, query_length);
        }
    }

    // an error was returned, pass it on to the API caller
    if(result.error != NULL) {
        httpd_resp_set_status(request, "400 Bad Request");
        response_msg = result.error;
    }

    httpd_resp_send(request, response_msg, strlen(response_msg));

    return ESP_OK;
}
httpd_uri_t get_root_uri = {
    .uri="/",
    .method=HTTP_GET,
    .handler=&on_http_get_root,
    .user_ctx = NULL
};

// Configure server and enable the http handler.
static
httpd_handle_t start_webserver(void) {
    httpd_handle_t server = NULL;
    httpd_config_t server_config = HTTPD_DEFAULT_CONFIG();

    LOGLN("Starting HTTPd server ':%d'.", server_config.server_port);

    if(httpd_start(&server, &server_config) == ESP_OK) {
        httpd_register_uri_handler(server, &get_root_uri);
        return server;
    }

    LOGLN("Failed to start HTTPd server.");
    return NULL;
}

// Start an http server and store it's handle in g_http_server.
static
void server_init(void) {
    g_http_server = start_webserver();
}

#endif // !_potion_party_server_h