Messages.pgc

#include <stdio.h>
#include <stdbool.h>
#include <malloc.h>
#include <time.h>
#include <stdlib.h>

#include <pgtypes.h>
#include <pgtypes_timestamp.h>
#include <ecpglib.h>
#include <ecpgerrno.h>
#include <sqlca.h>

#include "IO.h"
#include "Messages.h"
#include "Locks.h"
#include "Dialogs.h"

EXEC SQL WHENEVER SQLWARNING SQLPRINT;
EXEC SQL WHENEVER SQLERROR SQLPRINT;
EXEC SQL WHENEVER NOT FOUND CONTINUE;

void CreateMessagesTable()
{
    EXEC SQL CREATE TABLE Messages
    (
        MessageId    serial    PRIMARY KEY,
        Text         text      NOT NULL,
        SendDateTime timestamp NOT NULL DEFAULT current_timestamp,
        DialogId     int       NOT NULL,
        AuthorId     int       NOT NULL,
        FOREIGN KEY (DialogId) REFERENCES Dialogs (DialogId) ON DELETE CASCADE,
        FOREIGN KEY (AuthorId) REFERENCES Accounts (AccountId) ON DELETE CASCADE
    );

    EXEC SQL COMMIT;
}

void DropMessagesTable()
{
    EXEC SQL DROP TABLE IF EXISTS Messages CASCADE;

    EXEC SQL COMMIT;
}


void AddMessage(int authorId, int dialogId, char* message)
{
    EXEC SQL BEGIN DECLARE SECTION;
    int authorId_ = authorId;
    int dialogId_ = dialogId;
    char* message_ = message;
    EXEC SQL END DECLARE SECTION;

    EXEC SQL INSERT INTO Messages (Text, AuthorId, DialogId) VALUES (:message_, :authorId_, :dialogId_);

    EXEC SQL COMMIT;
}

void SendMessage(int authorId, int dialogId, char* message)
{
    AddMessage(authorId, dialogId, message);

    UnlockDialog(dialogId);
}

void StartSendingMessages(char* nickname, int dialogId)
{
    EXEC SQL BEGIN DECLARE SECTION;
    char* nickname_ = nickname;
    int authorId;
    EXEC SQL END DECLARE SECTION;

    EXEC SQL SELECT AccountId INTO :authorId FROM Accounts WHERE Nickname = :nickname_;

    while (true)
    {
        printf(" > ");
        char msg[MESSAGE_SIZE];
        while (InputLine(msg, MESSAGE_SIZE) <= 0)
        {

        }
        SendMessage(authorId, dialogId, msg);
    }
}

void GetPrintMessages(int dialogId, int lastMessages)
{
    EXEC SQL BEGIN DECLARE SECTION;
    int dialogId_ = dialogId;
    int offset;
    int count;
    timestamp ts;
    char msg[MESSAGE_SIZE];
    int authorId;
    char name1[STRING_SIZE];
    char name2[STRING_SIZE];
    int maxAuthorId;
    EXEC SQL END DECLARE SECTION;

    GetDialogTwoMembers(dialogId, name1, name2);
    EXEC SQL SELECT max(AccountId) INTO :maxAuthorId FROM AccountsDialogs WHERE DialogId = :dialogId_;

    if (lastMessages == -1)
    {
        offset = 0;
    }
    else
    {
        EXEC SQL SELECT count(*) INTO :count FROM Messages WHERE DialogId = :dialogId_;
        offset = count - lastMessages;
        offset = offset < 0 ? 0 : offset;
    }

    EXEC SQL DECLARE cursor5 CURSOR FOR
        SELECT Text, SendDateTime, AuthorId FROM Messages
        WHERE DialogId = :dialogId_
        ORDER BY SendDateTime
        OFFSET :offset;
    EXEC SQL OPEN cursor5;
    EXEC SQL WHENEVER NOT FOUND DO BREAK;
    while (true)
    {
        EXEC SQL FETCH cursor5 INTO :msg, :ts, :authorId;
        OutputMessage(authorId < maxAuthorId ? name1 : name2, msg, ts);
    }
    EXEC SQL WHENEVER NOT FOUND CONTINUE;
    EXEC SQL CLOSE cursor5;
}


void ReceiveMessage(int dialogId)
{
    EXEC SQL BEGIN DECLARE SECTION;
    int dialogId_ = dialogId;
    char msg[MESSAGE_SIZE];
    timestamp sendDateTime;
    int authorId;
    char authorName[STRING_SIZE];
    EXEC SQL END DECLARE SECTION;

    timestamp current;
    PGTYPEStimestamp_current(&current);
    char* currentstr = PGTYPEStimestamp_to_asc(current);
    char lockname[STRING_SIZE];
    sprintf(lockname, "%s-%d", currentstr, rand());
    PGTYPESchar_free(currentstr);

    Lock(lockname, dialogId);
    Wait(lockname);

    EXEC SQL SELECT Text, SendDateTime, AuthorId
        INTO :msg, :sendDateTime, :authorId
        FROM Messages
        WHERE DialogId = :dialogId_
        ORDER BY SendDateTime DESC
        LIMIT 1;

    EXEC SQL SELECT Nickname INTO :authorName FROM Accounts WHERE AccountId = :authorId;

    OutputMessage(authorName, msg, sendDateTime);

    EXEC SQL COMMIT;
}

void StartReceivingMessages(int dialogId, int lastMessages)
{
    EXEC SQL BEGIN DECLARE SECTION;
    int dialogId_ = dialogId;
    EXEC SQL END DECLARE SECTION;

    printf("Диалог №%d:\n", dialogId_);

    GetPrintMessages(dialogId, lastMessages);

    while (true)
    {
        ReceiveMessage(dialogId_);
    }
}