typedef struct {
    unit8_t num;
    char** name;
    char** value;
} HttpParams;

typedef struct {
    char* name;
    void (*fn)(HttpParams*);
} ActionCallback;

#define MAX_CB 10

ActionCallback cb[MAX_CB];
uint8_t numCb = 0;

void ShowParams(HttpParams* params) {
    for (int i = 0; i < params->num; ++i) {
        Serial.print(params->name[i]);
        Serial.print(": ");
        Serial.println(params->value[i]);
    }
}

void LedFunc(HttpParams* params) {
    for (int i = 0; i < params->num; ++i) {
        int val = strcmp(params->value[i], "LOW") == 0 ? 0 : 1;
        int pin = 0;
        if (strcmp(params->name[i], "P3") == 0) {
            pin = 3;
        } else if (strcmp(params->name[i], "P5") == 0) {
            pin = 5;
        }

        if (pin > 0) {
            digitalWrite(pin, val);
        }
    }
}

void registerFunc(char* key, void (*fn)(HttpParams*)) {
    cb[numCb].name = key;
    cb[numCb].fn = fn;
}

void setup() {
    Serial.begin(115200);
    registerFunc("echo", &ShowParams);
    registerFunc("led", &LedFunc);
}

void loop() {
    //stuff
}