#include <stdio.h>
#include <string.h>

#define MAX_INLINE 200
#define MAX_OUT_FN 100

int debug = 0,
    trace = 0,
    info = 0;

int readline(FILE *f, char *ln)
{   char ch;
    int i = 0;

    while ((ch = (char)fgetc(f)) != '\n')
       if (feof(f))
           break;
       else if (i < MAX_INLINE)
           ln[i++] = ch;
    ln[i] = '\0';

    return !feof(f) || ln[0] != '\0';
}

int begin_line(char *line, char *fn)
{   int i, j;

    fn[0] = '\0';
    if (strncmp(line, "begin ", 6))
        return 0;
  
    for (i = 7; line[i] >= '0' && line[i] <= '9'; i++);
    if (i == 7 || line[i] != ' ')
        return 0;

    while (line[i] == ' ')
        i++;

    for (j = 0; line[i] != ' ' && line[i] != '\0'; i++)
        if (j < MAX_OUT_FN)
           fn[j++] = line[i];
    fn[j] = '\0';

    return line[i] == '\0';
}

int end_line(char *line)
{   return !strcmp(line, "end");
}

int decode_ch(char ch)
{   return (ch == '`' ? ' ' : ch) - 32;
}
 
int correct_line(char *line)
{   int l, i, sl = strlen(line);

    if (line[0] < ' ' || line[0] > '`')
    {   if (debug)
            printf("first `%c'\n", line[0]);
        return 0;
    }
    l = decode_ch(line[0]);
    if ((sl - 1)/4 != (l + 2)/ 3)
    {   if (debug)
            printf("%d %d %d %d\n", 
        strlen(line), l, (strlen(line) - 1)/4, (l + 2)/3);
        return 0;
    }
    for (i = 1; i < sl; i++)
        if (line[i] < ' ' || line[i] > '`')
        {   if (debug)
                printf("line[%d] = `%c'", i, line[i]);
            return 0;
        } 
    return 1;
}

void decode_line(char *line, FILE *f)
{   int l = decode_ch(line[0]),
        sl = strlen(line),
        i, j;

    for (j = 0, i = 1; i < sl;)
    {   int c1, c2, c3, c4,
             b1, b2, b3;
        c1 = decode_ch(line[i++]);
        c2 = decode_ch(line[i++]);
        c3 = decode_ch(line[i++]);
        c4 = decode_ch(line[i++]);
        b1 = (c1 << 2) | (c2 >> 4);
        b2 = (c2 << 4) | (c3 >> 2);
        b3 = (c3 << 6) | c4;
        if (j++ < l)
            fputc(b1, f);
        if (j++ < l)
            fputc(b2, f);
        if (j++ < l)
            fputc(b3, f);
    }
}

void uudecode_file(char *fn)
{   FILE *fin = fopen(fn, "r");
    char line[MAX_INLINE + 1];
    char out_fn[MAX_OUT_FN + 1];

    printf("uudecode file: %s\n", fn);
    if (fin == NULL)
    {   printf("Error: cannot open `%s'\n", fn);
        return;
    }
    while (readline(fin, line))
    {   while (!begin_line(line, out_fn))
        {   if (info)
                printf("Skipping: %s\n", line);
            if (!readline(fin, line))
                break;
        }
        if (out_fn[0] != '\0')
        {  FILE *fout = fopen(out_fn, "w");
           printf("Outfile: %s\n", out_fn);
           if (fout == NULL)
               printf("Error: cannot open file %s\n", out_fn);
           while (readline(fin, line) && !end_line(line))
           {   if (correct_line(line))
               {   if (fout != NULL)
                       decode_line(line, fout);
               }
               else if (trace)
                   printf("Ignoring: %s\n", line);
           }
           if (fout != NULL)
               fclose(fout);
        }
    }

    fclose(fin);
}

void main(int argc, char *argv[])
{   int i;
    
    for (i = 1; i < argc; i++)
    {   char *arg = argv[i];
        if (!strcmp(arg, "+d"))
            debug = 1;
        else if (!strcmp(arg, "-d"))
            debug = 0;
        else if (!strcmp(arg, "+t"))
            trace = 1;
        else if (!strcmp(arg, "-t"))
            trace = 0;
        else if (!strcmp(arg, "+i"))
            info = 1;
        else if (!strcmp(arg, "-i"))
            info = 0;
        else 
            uudecode_file(argv[i]); 
    }
}