#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <algorithm>

#define SERIAL "/dev/ttyS0"
#define BAUDRATE B9600

#define NUM_ENDBUF 8

int tty_fd, flags;

void send(unsigned char what) {

    write(tty_fd, &what ,1);
}

void send(unsigned char* buffer, uint32_t length) {

//  sleep(1);
    write(tty_fd, buffer, length);
}

void recieve(unsigned char* buffer, unsigned int length) {

    read(tty_fd,buffer,length);
}

int main(int argc,char** argv)
{
    if (argc<2) {
        printf("Usage: com <filename>\n");
        return 1;
    }

    // Load file
    FILE* file = fopen(argv[1], "rb");
    if (file==NULL) {
        printf("File %s not found\n", argv[1]);
        return 1;
    }

    // Get file length
    fseek(file,0,SEEK_END);
    uint32_t length = ftell(file);
    fseek(file,0,SEEK_SET);

    // Load data
    unsigned char* buffer = new unsigned char[length];
    fread(buffer, sizeof(char),length,file);

    printf("Sending file %s (%d bytes, %d chunks)\n", argv[1], length, length>>8);

    struct termios tio;
    memset(&tio,0,sizeof(tio));

    cfsetospeed(&tio,BAUDRATE);
    cfsetispeed(&tio,BAUDRATE);

    tio.c_iflag=0;
    tio.c_oflag=0;
    tio.c_cflag=CS8|CREAD|CLOCAL|CRTSCTS; // Obs, CRTSCTS är ny
    tio.c_lflag=0;
    tio.c_cc[VMIN]=1;
    tio.c_cc[VTIME]=5;
    if((tty_fd = open(SERIAL , O_RDWR)) == -1){ //  | O_DSYNC
            printf("Error while opening %s\n\r", SERIAL);
            return -1;
    }
    tcsetattr(tty_fd,TCSANOW,&tio);

    tcflush(tty_fd, TCIOFLUSH);

    // Send size as four bytes, MSB first, to initialize transfer
    send((length>>24)&0xff);
    send((length>>16)&0xff);
    send((length>>8)&0xff);
    send((length)&0xff);

    printf("Sent length\n");

    bool done=false;
    uint16_t lastchunknr=-1;
    while (!done) {

        // Get chunk number
        uint16_t chunknr=0;

        uint8_t input[2];
        recieve( &input[0], 2);

        chunknr=(input[0]<<8) | input[1];

        //printf("\nchunknr:%x\n", chunknr);

        // If chunk $ffff is asked for, kindly exit
        if (chunknr==0xffff) {

            printf("\nQuitting...\n");
            exit(0);
        }

        // Just debug
        if (chunknr==lastchunknr) printf("\n\n\rResending chunk %d\n\n",chunknr);
        lastchunknr=chunknr;

        uint32_t chunklength = std::min(uint32_t(256),uint32_t(length-chunknr*256));

        // Send checksum
        uint8_t checksum=0;
        for (uint32_t i=0; i<chunklength; i++) {
            checksum+=buffer[chunknr*256+i];  // (will %256 automatic)
        }
        printf("\nSending chunk [%3d of %3d]   (checksum:%3d, length:%3d) ", chunknr,length>>8, checksum, chunklength);
        fflush(stdout);

        send(checksum);

        send(uint8_t(chunklength-1));

        tcdrain(tty_fd);

        // Send part
        send(buffer+(chunknr<<8), chunklength);

        tcdrain(tty_fd);

        // Send some crap at the end just to make sure, code
        // timeout on the amiga to cope with this instead
        uint8_t endbuf[NUM_ENDBUF];
        for (int i=0; i<NUM_ENDBUF; i++) endbuf[i]=65;
        write(tty_fd,endbuf, NUM_ENDBUF);

        tcdrain(tty_fd);
    }

    printf("File sent, exiting...\n\n");

    close(tty_fd);
    return EXIT_SUCCESS;
}