api_server.hpp

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#ifndef API_SERVER_HPP__
#define API_SERVER_HPP__
 
#include <map>
#include <functional>
 
//#include <Arduino.h>
#include <Ticker.h>
#include <AsyncTCP.h>
#include <ESPAsyncWebServer.h>
 
#include "app_config.hpp"
 
// Callback function with string argument
using CbStringT = std::function<void(const String&)>;
// Callback function with float argument
using CbFloatT = std::function<void(const float)>;
// Callback function with integer argument
using CbIntT = std::function<void(const int)>;
// Callback function without arguments
using CbVoidT = std::function<void(void)>;
 
// Mapping used for resolving command strings received via HTTP request
// on the "/cmd" endpoint to specialised request handlers
using CmdMapT = std::map<String, CbStringT>;
// String replacement mapping for template processor
using TemplateMapT = std::map<String, String>;
 
 
class APIServer
{
public:
    // API server configuration
    static constexpr APIServerConfig srv_conf{};
    // Base ESPAsyncWebServer
    AsyncWebServer* backend;
    // Server-Sent Events (SSE) for "PUSH" updates of application data
    AsyncEventSource* event_source;
    // Callback registry, see above
    CmdMapT cmd_map;
    // String replacement mapping for template processor
    TemplateMapT template_map;
    // Can be polled externally as an alternative to conf_enable_reboot=true
    bool reboot_requested;
 
    
    APIServer(AsyncWebServer* http_backend);
    ~APIServer();
 
    void set_template(const char* placeholder, const char* replacement);
 
    void register_api_cb(const char* cmd_name, CbStringT cmd_callback);
    void register_api_cb(const char* cmd_name, CbFloatT cmd_callback);
    void register_api_cb(const char* cmd_name, CbIntT cmd_callback);
    void register_api_cb(const char* cmd_name, CbVoidT cmd_callback);
 
    void begin();
 
 
private:
    // Add Request URL rewrites to the server instance
    void _add_rewrites();
    // Add URL redirects to the server instance
    void _add_redirects();
    // Add request handlers to the server instance
    void _add_handlers();
    // Activate the SSE envent source if conf_use_sse == true
    void _add_event_source();
    // Helper function for _add_event_source, only sends "Hello" message and info print
    void _register_sse_on_connect_callback();
 
 
    // on("/")
    void _on_root_request(AsyncWebServerRequest *request);
    // on("/cmd")
    void _on_cmd_request(AsyncWebServerRequest *request);
    // on("/update")
    // When update is initiated via GET
    void _on_update_request(AsyncWebServerRequest *request);
    // When file is uploaded via POST request
    static void _on_update_body_upload(
        AsyncWebServerRequest *request, const String& filename,
        size_t index, uint8_t *data, size_t len, bool final);
    // Catch-All-Handlers
    static void _on_request(AsyncWebServerRequest *request);
    static void _on_body(AsyncWebServerRequest *request,
        uint8_t *data, size_t len, size_t index, size_t total);
    static void _on_upload(AsyncWebServerRequest *request, const String& filename,
        size_t index, uint8_t *data, size_t len, bool final);
 
    // Template processor
    String _template_processor(const String& placeholder);
};
 
#endif /* API_SERVER_HPP__ */