feat: coingecko api

config.def.h

@@ -1,10 +1,12 @@
-#define CUR "$"
+#define FMT "%s=$%f"
 
-struct wallet_s {
-    char *from;
-    char *to;
-    float value;
+// curl https://api.coingecko.com/api/v3/simple/supported_vs_currencies
+#define VS "usd"
+
+// curl https://api.coingecko.com/api/v3/coins/list
+static const struct wallet_s {
+    char *id;   char *fmt;  float value;
 } WALLET[] = {
-    {"BTC",  "USDT", 1.00000000},
+    {"bitcoin", "BTC",      1.00000000},
     {0},
 };

crypto.c

@@ -7,18 +7,15 @@
 #include <sys/param.h>
 #include "config.h"
 
-#define BUF_SIZE 1024
+#define ARRLEN(a)   (sizeof (a) / sizeof *(a))
+#define BUF_SIZE    256 * ARRLEN(WALLET)
 
-// [{"symbol":"BTCUSDT","price":"69420.69420"}]
-static int get_next_symbol(char* buf, float* price)
+// {"bitcoin":{"usd":69420.69}}
+static int get_next_symbol(char *buf, float *price)
 {
-    static const char output[] = "\"symbol\":\"%*[^\"]\",\"price\":\"%f\"";
-    char* tmp = strtok(buf, "{");
+    static const char output[] = "\"%*[a-z]\":{\"" VS "\":%f}";
+    char *tmp = strtok(buf, ",");
 
-    if (!tmp) {
-        return 1;
-    }
-    tmp = strtok(0, "}");
     if (!tmp) {
         return 1;
     }
@@ -27,73 +24,65 @@ static int get_next_symbol(char* buf, float* price)
 
 static size_t write_callback(char *response, size_t s, size_t n, void *buf)
 {
-    size_t size = s * n;
-
-    return snprintf(buf, MIN(size, BUF_SIZE), response);
+    return snprintf(buf, MIN(s * n, BUF_SIZE), response);
 }
 
-static char* build_url(void)
+static char *build_url(void)
 {
-    const char base[] =
-        "https://api.binance.com/api/v3/ticker/price?symbols=[";
-    size_t s = sizeof base;
-    char* url;
-    char* tmp = (char*)s - 1;
+    const char base[] = "https://api.coingecko.com/api/v3/simple/price?ids=%s&vs_currencies=" VS;
+    size_t ids_size = 0;
+    char *url;
+    char ids[BUF_SIZE] = {0};
 
-    for (size_t i = 0; WALLET[i].to; i++) {
-        s += strlen(WALLET[i].from) + strlen(WALLET[i].to) + 3; // ["SYMBOL",]
+    for (size_t i = 0; WALLET[i].id; i++) {
+        strcpy(ids + ids_size, WALLET[i].id);
+        ids_size += strlen(WALLET[i].id);
+        ids[ids_size++] = ',';
     }
-    url = malloc(s);
+    ids[ids_size - 1] = '\0';
+    url = malloc(sizeof base + ids_size * (sizeof *url));
     if (!url) {
-        return 0;
+        return NULL;
     }
-    strcpy(url, base);
-    tmp += (size_t)url;
-    for (size_t i = 0; WALLET[i].to; i++) {
-        tmp += sprintf(tmp, "\"%s%s\",", WALLET[i].from, WALLET[i].to);
-    }
-    url[strlen(url) - 1] = ']';
+    sprintf(url, base, ids);
     return url;
 }
 
-static CURL* init_curl(char* response)
+static int perform_request(char *response)
 {
-    char* url = build_url();
-    CURL* curl = curl_easy_init();
-
+    char *url = build_url();
+    CURL *curl = curl_easy_init();
 
     if (!url || !curl) {
         free(url);
         curl_easy_cleanup(curl);
-        return 0;
+        return 1;
     }
     curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
     curl_easy_setopt(curl, CURLOPT_WRITEDATA, response);
     curl_easy_setopt(curl, CURLOPT_URL, url);
     curl_easy_perform(curl);
+    curl_easy_cleanup(curl);
     free(url);
-    return curl;
+    return 0;
 }
 
 int main(void)
 {
     char response[BUF_SIZE];
-    CURL* curl = init_curl(response);
-    int err;
-    float price, current;
-    float sum = 0;
+    int err = perform_request(response);
+    float price, current, sum = 0;
 
-    if (!curl) {
+    if (err) {
         error(1, errno, "cannot init curl");
     }
-    err = get_next_symbol(response, &price);
-    for (size_t i = 0; !err && WALLET[i].to; i++) {
+    err = get_next_symbol(response + 1, &price);
+    for (size_t i = 0; !err && WALLET[i].id; i++) {
         current = price * WALLET[i].value;
-        printf("%s=%.2f" CUR " ", WALLET[i].from, current);
+        printf(FMT " ", WALLET[i].fmt, current);
         sum += current;
-        err = get_next_symbol(0, &price);
+        err = get_next_symbol(NULL, &price);
     }
-    printf("TOT=%.2f" CUR "\n", sum);
-    curl_easy_cleanup(curl);
+    printf(FMT, "TOT", sum);
     return 0;
 }