feat: add Postgresql && routes user

Makefile

@@ -1,6 +1,6 @@
 CC = gcc
-CFLAGS = -Wall -g
-LIBS = -lmicrohttpd
+CFLAGS = -Wall -g -I/usr/include/postgresql
+LIBS = -lmicrohttpd -L/usr/lib/x86_64-linux-gnu -lpq
 SRCDIR = src
 BINDIR = bin
 

README.md

@@ -10,6 +10,9 @@ I've deliberately chosen the C programming language for this project to challeng
 
 My primary goal was to gain a deeper understanding of how APIs function under the hood and how they communicate with the underlying operating system. The C language is exceptionally suited for this purpose due to its low-level nature and direct interaction with hardware and system resources.
 
+## Postgres Database
+In this project, I'm using a Postgres database to store user information. The database is hosted on cloud in the [supabase](https://supabase.com/), and the server communicates with it using the [libpq](https://www.postgresql.org/docs/9.1/libpq.html) library.
+
 ## How to Run the Server
 
 ### Prerequisites:
@@ -29,7 +32,11 @@ My primary goal was to gain a deeper understanding of how APIs function under th
    cd rest-api-C
    ```
 
-3. Running the Server:
+3. Update the Database Credentials
+   - Open the `pg.h` file in the `src` directory.
+   - Update the variables with your database credentials.
+
+4. Running the Server:
    - Using Docker:
      ```bash
      docker build -t rest-api-c .
@@ -45,15 +52,14 @@ My primary goal was to gain a deeper understanding of how APIs function under th
      ./bin/main
      ```
 
-4. Access the API at http://localhost:8080
+5. Access the API at http://localhost:8080
 
 ## Endpoints (Work in Progress)
 
 This RESTful web server provides the following endpoints (please note that this section is a work in progress):
 
-- **GET /:** Welcome message and basic information about the API (not yet implemented).
-- **GET /users:** Retrieve a list of users (not yet implemented).
-- **GET /users/{id}:** Retrieve detailed information about a specific user (not yet implemented).
+- **GET /users:** Retrieve a list of users.
+- **GET /users/{id}:** Retrieve detailed information about a specific user.
 - **POST /users:** Create a new user (not yet implemented).
 - **PUT /users/{id}:** Update information for a specific user (not yet implemented).
 - **DELETE /users/{id}:** Delete a user (not yet implemented).

build.sh

@@ -4,4 +4,4 @@ set -e
 
 mkdir -p bin
 
-gcc -o bin/main src/main.c -lmicrohttpd
+gcc -o bin/main src/main.c -lmicrohttpd -I/usr/include/postgresql -L/usr/lib/x86_64-linux-gnu -lpq

dockerfile

@@ -3,7 +3,7 @@ FROM gcc:latest
 
 # Instale as dependências necessárias
 RUN apt-get update && \
-    apt-get install -y libmicrohttpd-dev make nginx
+    apt-get install -y libmicrohttpd-dev make nginx libpq-dev
 
 RUN mkdir -p /app
 

src/handler.h

@@ -1,4 +1,11 @@
 #include "response_builder.h"
+#include "user_handler.h"
+#include <setjmp.h>
+
+jmp_buf exceptionBuffer;
+
+#define TRY if (setjmp(exceptionBuffer) == 0)
+#define CATCH else
 
 void log_api(const char *url, const char *method) {
   printf("[%s] %s\n", method, url);
@@ -12,29 +19,43 @@ enum MHD_Result default_handler(void *cls, struct MHD_Connection *connection, co
   int ret;
 
   struct MHD_Response *response;
-  HTTP_status status;
-  char *response_body = NULL;
+  HTTP_response response_api;
 
   log_api(url_str, method_str);
 
-  if (strcmp(url_str, "/") == 0) {
-    response_body = simple_message("Hello, world!");
-    status = OK;
-  } else if (strcmp(url_str, "/users") == 0) {
-    // mandar para modulo de usuarios
-    response_body = simple_message("Sorry, this endpoint is not implemented yet");
-    status = OK;
-  } else {
-    response_body = simple_message("Not found");
-    status = NOT_FOUND;
+  TRY {
+    if (strcmp(url_str, "/") == 0) {
+      response_api = (HTTP_response){
+        .body = simple_message("Hello world!"),
+        .status = OK
+      };
+    }
+
+    else if (is_valid_route(url_str, "/users")) {
+      response_api = user_router(url_str, method_str, upload_data);
+    }
+
+    else {
+      response_api = (HTTP_response){
+        .body = simple_message("Not found"),
+        .status = NOT_FOUND
+      };
+    }
+  } CATCH {
+    response_api = (HTTP_response){
+      .body = simple_message("Internal server error"),
+      .status = INTERNAL_SERVER_ERROR
+    };
+
+    printf("Internal server error");
   }
 
-  response = HTTP_build_response_JSON(response_body, status);
+  response = HTTP_build_response_JSON(response_api.body);
 
   if (!response)
     return MHD_NO;
 
-  ret = MHD_queue_response(connection, status, response);
+  ret = MHD_queue_response(connection, response_api.status, response);
   MHD_destroy_response(response);
 
   return ret;

src/main.c

@@ -6,18 +6,18 @@
 #define PORT 8080
 
 int main() {
-    printf("Starting server on port %d\n", PORT);
+  printf("Starting server on port %d\n", PORT);
 
-    struct MHD_Daemon *daemon;
+  struct MHD_Daemon *daemon;
 
-    daemon = MHD_start_daemon(MHD_USE_THREAD_PER_CONNECTION, PORT, NULL, NULL,
-                              &default_handler, NULL, MHD_OPTION_END);
-    if (!daemon)
-        return 1;
+  daemon = MHD_start_daemon(MHD_USE_THREAD_PER_CONNECTION, PORT, NULL, NULL,
+                            &default_handler, NULL, MHD_OPTION_END);
+  if (!daemon)
+    return 1;
 
-    getchar();
+  getchar();
 
-    MHD_stop_daemon(daemon);
+  MHD_stop_daemon(daemon);
 
-    return 0;
+  return 0;
 }

src/pg.h

@@ -0,0 +1,85 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libpq-fe.h>
+
+#define database "*****"
+#define user "*****"
+#define password "*****"
+#define host "*****"
+#define port "*****"
+
+char *executeQueryToJson(const char *query);
+
+char *formatResultAsJson(PGresult *result);
+
+char *executeQueryToJson(const char *query) {
+    PGconn *conn = PQconnectdb(
+        "user=" user
+        " password=" password
+        " dbname=" database
+        " host=" host
+        " port=" port
+    );
+
+    if (PQstatus(conn) != CONNECTION_OK) {
+        fprintf(stderr, "Connection to database failed: %s", PQerrorMessage(conn));
+        PQfinish(conn);
+        return NULL;
+    }
+
+    PGresult *result = PQexec(conn, query);
+
+    if (PQresultStatus(result) != PGRES_TUPLES_OK) {
+        fprintf(stderr, "Query execution failed: %s", PQerrorMessage(conn));
+        PQclear(result);
+        PQfinish(conn);
+        return NULL;
+    }
+
+    char *jsonResult = formatResultAsJson(result);
+
+    PQclear(result);
+    PQfinish(conn);
+
+    return jsonResult;
+}
+
+char *formatResultAsJson(PGresult *result) {
+    int numFields = PQnfields(result);
+    int numRows = PQntuples(result);
+
+    // Calcula o tamanho total necessário para a string JSON -> para não estourar o buffer
+    int totalSize = numRows * (2 + numFields * 256) + numRows - 1 + 3;
+    // Cada campo contribui com pelo menos 256 caracteres, 2 para aspas e 1 para vírgula
+    // numRows - 1 é para as vírgulas entre objetos JSON
+    // 3 é para as chaves finais e terminador de string
+
+    char *json = (char *)malloc(totalSize);
+    json[0] = '\0';
+
+    if (numRows == 0) {
+        strcat(json, "[]");
+        return json;
+    }
+
+    for (int i = 0; i < numRows; ++i) {
+        strcat(json, "{");
+        for (int j = 0; j < numFields; ++j) {
+            if (j > 0) strcat(json, ",");
+            char *fieldName = PQfname(result, j);
+            char *fieldValue = PQgetvalue(result, i, j);
+
+            strcat(json, "\"");
+            strncat(json, fieldName, totalSize - strlen(json) - 5);
+            strcat(json, "\":\"");
+            strncat(json, fieldValue, totalSize - strlen(json) - 5);
+            strcat(json, "\"");
+        }
+        strcat(json, "}");
+        if (i < numRows - 1) strcat(json, ",");
+    }
+
+    return json;
+}
+

src/response_builder.h

@@ -1,7 +1,7 @@
 #include <microhttpd.h>
-#include "types.h"
+#include "utils.h"
 
-struct MHD_Response *HTTP_build_response_JSON(const char *message, HTTP_status status) {
+struct MHD_Response *HTTP_build_response_JSON(const char *message) {
   struct MHD_Response *response;
 
   response = MHD_create_response_from_buffer(strlen(message), (void *)message, MHD_RESPMEM_PERSISTENT);

src/user_handler.h

@@ -0,0 +1,93 @@
+#include "pg.h"
+#include <string.h>
+#include <stdio.h>
+
+HTTP_response get_all(const char *url) {
+  const char *query = "SELECT * FROM users";
+
+  char *result = executeQueryToJson(query);
+
+  if (result == NULL) {
+    return (HTTP_response){
+      .body = simple_message("Internal server error"),
+      .status = INTERNAL_SERVER_ERROR
+    };
+  }
+
+  return (HTTP_response){
+    .body = result,
+    .status = OK
+  };
+}
+
+HTTP_response get_one(const char *user_id) {
+  char query[64];
+  snprintf(query, sizeof(query), "SELECT * FROM users WHERE id = %s", user_id);
+
+  char *result = executeQueryToJson(query);
+
+  if (result == NULL) {
+    return (HTTP_response){
+      .body = simple_message("Internal server error"),
+      .status = INTERNAL_SERVER_ERROR
+    };
+  }
+
+  return (HTTP_response){
+    .body = result,
+    .status = OK
+  };
+}
+
+HTTP_response create(const char *body) {
+  return (HTTP_response){
+    .body = simple_message("create"),
+    .status = OK
+  };
+}
+
+HTTP_response update(const char *user_id, const char *body) {
+  return (HTTP_response){
+    .body = simple_message("update"),
+    .status = OK
+  };
+}
+
+HTTP_response drop(const char *user_id) {
+  return (HTTP_response){
+    .body = simple_message("drop"),
+    .status = OK
+  };
+}
+
+HTTP_response user_router(const char *url, const char *method, const char *body){
+  char *user_id = strstr(url, "/users/");
+  if (user_id != NULL) {
+    user_id += strlen("/users/");
+  }
+
+  if (is_valid_method(method, "GET")) {
+      if(user_id == NULL){
+        return get_all(url);
+      } else {
+        return get_one(user_id);
+      }
+  }
+
+  if (is_valid_method(method, "POST")) {
+    return create(body);
+  }
+
+  if (is_valid_method(method, "PUT")) {
+    return update(user_id, body);
+  } 
+
+  if (is_valid_method(method, "DELETE")) {
+    return drop(user_id);
+  }
+
+  return (HTTP_response){
+    .body = simple_message("Not implemented"),
+    .status = NOT_IMPLEMENTED
+  };
+}