#include <pthread.h>
#include "tlibc/filesystem.h"
#include "tlibc/time.h"
#include "db/idb.h"
#include "server.h"
#include "config.h"
#include "log.h"
#include "network/tcp-chat-protocol/v1.h"

typedef struct ConnectionHandlerArgs {
    Socket accepted_socket;
    EndpointIPv4 client_end;
    u64 session_id;
} ConnectionHandlerArgs;

static void* handle_connection(void* _args);
static Result(void) try_handle_connection(ConnectionHandlerArgs* args, cstr log_ctx);


static ServerCredentials* _server_credentials = NULL;


static Result(void) parseConfig(cstr config_path){
    Deferral(8);

    // open file
    try(FILE* config_file, p, file_open(config_path, FO_ReadExisting));
    Defer(file_close(config_file));
    // read whole file into Array(char)
    try(i64 config_file_size, i, file_getSize(config_file));
    Array(char) config_buf = Array_alloc(char, config_file_size);
    Defer(free(config_buf.data));
    try_void(file_readBytesArray(config_file, config_buf));
    str config_str = Array_castTo_str(config_buf, false);

    str sk_base64;
    str pk_base64;
    try_void(config_findValue(config_str, STR("rsa_private_key"), &sk_base64, true));
    try_void(config_findValue(config_str, STR("rsa_public_key"), &pk_base64, true));
    char* sk_base64_cstr = str_copy(sk_base64).data;
    char* pk_base64_cstr = str_copy(pk_base64).data;
    Defer(
        free(sk_base64_cstr);
        free(pk_base64_cstr);
    );
    try(_server_credentials, p, ServerCredentials_create(sk_base64_cstr, pk_base64_cstr));
    
    Return RESULT_VOID;
}

Result(void) server_run(cstr server_endpoint_cstr, cstr config_path){
    Deferral(32);
    cstr log_ctx = "Server/MainThread";
    logInfo(log_ctx, "starting server");
    logDebug(log_ctx, "parsing config");
    try_void(parseConfig(config_path));
    Defer(ServerCredentials_free(_server_credentials));

    logDebug(log_ctx, "initializing main socket");
    EndpointIPv4 server_end;
    try_void(EndpointIPv4_parse(server_endpoint_cstr, &server_end));
    try(Socket main_socket, i, socket_open_TCP());
    try_void(socket_bind(main_socket, server_end));
    try_void(socket_listen(main_socket, 512));
    logInfo(log_ctx, "server is listening at %s", server_endpoint_cstr);

    u64 session_id = 1;
    while(true){
        ConnectionHandlerArgs* args = (ConnectionHandlerArgs*)malloc(sizeof(ConnectionHandlerArgs));
        try(args->accepted_socket, i, socket_accept(main_socket, &args->client_end));
        args->session_id = session_id++;
        pthread_t conn_thread = {0};
        //TODO: use async IO instead of threads to not waste system resources 
        // while waiting for incoming data in 100500 threads
        try_stderrcode(pthread_create(&conn_thread, NULL, handle_connection, args));
        try_stderrcode(pthread_detach(conn_thread));
    }

    Return RESULT_VOID;
}

static void* handle_connection(void* _args){
    ConnectionHandlerArgs* args = (ConnectionHandlerArgs*)_args;
    char log_ctx[64];
    sprintf(log_ctx, "Session-" IFWIN("%llx", "%lx"), args->session_id);
    
    ResultVar(void) r = try_handle_connection(args, log_ctx);
    if(r.error){
        str error_s = Error_toStr(r.error);
        logError(log_ctx, "%s", error_s.data);
        free(error_s.data);
    }
    
    return NULL;
}

static Result(void) try_handle_connection(ConnectionHandlerArgs* args, cstr log_ctx){
    Deferral(64);
    Defer(free(args));
    
    ClientConnection* conn = NULL;
    Defer(
        ClientConnection_close(conn);
        logInfo(log_ctx, "session closed");
    );
    // establish encrypted connection
    try(conn, p, 
        ClientConnection_accept(
            _server_credentials,
            args->accepted_socket,
            args->client_end,
            args->session_id
        )
    );
    logInfo(log_ctx, "session accepted");

    // handle unauthorized requests
    bool ahtorized = false;
    PacketHeader req_header = {0};
    PacketHeader res_header = {0};
    while(!ahtorized){
        sleepMsec(50);
        //TODO: implement some additional check if socket is dead or not

        try_void(EncryptedSocketTCP_recvStruct(&conn->sock, &req_header));
        try_void(PacketHeader_validateMagic(&req_header));
        //TODO: move request handlers to separate functions
        switch(req_header.type){
            default:{
                Array(u8) err_buf = Array_alloc(u8, 128);
                bool err_complete = false;
                Defer(if(!err_complete) free(err_buf.data));
                sprintf(err_buf.data, "Received unexpected packet of type %u", 
                    req_header.type);
                err_buf.size = strlen(err_buf.data);

                PacketHeader_construct(&res_header, 
                    PROTOCOL_VERSION, PacketType_ErrorMessage, err_buf.size);
                try_void(EncryptedSocketTCP_sendStruct(&conn->sock, &res_header));
                //TODO: limit ErrorMessage size to fit into EncryptedSocketTCP.internal_buffer_size
                try_void(EncryptedSocketTCP_send(&conn->sock, err_buf));

                err_complete = true;
                Return RESULT_ERROR(err_buf.data, true);
            }

            case PacketType_ServerPublicInfoRequest:{
                ServerPublicInfoRequest req = {0};
                try_void(PacketHeader_validateContentSize(&req_header, sizeof(req)));
                try_void(EncryptedSocketTCP_recvStruct(&conn->sock, &req));

                //TODO: try find requested info
                Array(u8) content;

                PacketHeader_construct(&res_header,
                    PROTOCOL_VERSION, PacketType_ServerPublicInfoResponse, content.size);
                try_void(EncryptedSocketTCP_sendStruct(&conn->sock, &res_header));
                try_void(EncryptedSocketTCP_send(&conn->sock, content));
                break;
            }

            case PacketType_LoginRequest:{
                LoginRequest req = {0};
                try_void(PacketHeader_validateContentSize(&req_header, sizeof(req)));
                try_void(EncryptedSocketTCP_recvStruct(&conn->sock, &req));

                //TODO: try authorize client
                u64 user_id;
                u64 landing_channel_id;

                LoginResponse res = {0};
                LoginResponse_construct(&res, &res_header, user_id, landing_channel_id);
                try_void(EncryptedSocketTCP_sendStruct(&conn->sock, &res_header));
                try_void(EncryptedSocketTCP_sendStruct(&conn->sock, &res));
                ahtorized = true;
                logInfo(log_ctx, "client authorized");
                break;
            }

            case PacketType_RegisterRequest:{
                RegisterRequest req = {0};
                try_void(PacketHeader_validateContentSize(&req_header, sizeof(req)));
                try_void(EncryptedSocketTCP_recvStruct(&conn->sock, &req));

                //TODO: try register client
                u64 user_id;

                RegisterResponse res = {0};
                RegisterResponse_construct(&res, &res_header, user_id);
                try_void(EncryptedSocketTCP_sendStruct(&conn->sock, &res_header));
                try_void(EncryptedSocketTCP_sendStruct(&conn->sock, &res));
                break;
            }
        }
    }

    // handle authorized requests
    while(true){
        sleepMsec(50);
    }

    Return RESULT_VOID;
}