#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include "util.h"
#include "ReadLine.h"


/* Pass in a pointer to a token list. Is freed and then set to null */
void
FreeTokens(INOUTP char ***TokensPtr)
{
    assert(*TokensPtr);
    assert(**TokensPtr);

    free(**TokensPtr);		/* Free the string data */
    free(*TokensPtr);		/* Free token list */
    *TokensPtr = NULL;		/* Invalidate pointer since mem is gone */
}


/* Returns number of tokens in list. Zero if null list */
int
CountTokens(INP char **Tokens)
{
    int count = 0;

    if(NULL == Tokens)
	{
	    return 0;
	};
    while(Tokens[count])
	{
	    ++count;
	};
    return count;
}


/* Reads in a single line from file, splits into tokens and allocates
 * a list of tokens. Returns the an array of character arrays with the
 * final item being marked by an empty string.
 * Returns NULL on EOF
 * NB: Token list is does as two allocations, one for pointer list
 * and one for character array. Free what pointer points to and then
 * free the pointer itself */
char **
ReadLineTokens(INOUTP FILE * InFile,
	       INOUTP int *LineNum)
{

    enum
    { BUFFSIZE = 65536 };	/* This is much more than enough */
    char Buffer[BUFFSIZE];	/* Must match BUFFSIZE */
    char *Res;
    char *Last;
    char *Cur;
    char *Dst;
    char **Tokens;
    int TokenCount;
    int Len;
    int CurToken;
    boolean InToken;

    do
	{
	    /* Read the string */
	    Res = fgets(Buffer, BUFFSIZE, InFile);
	    if(NULL == Res)
		{
		    if(feof(InFile))
			{
			    return NULL;	/* Return NULL on EOF */
			}
		    else
			{
			    printf(ERRTAG "Unexpected error reading file\n");
			    exit(1);
			}
		}
	    ++(*LineNum);

	    /* Strip newline if any */
	    Last = Buffer + strlen(Buffer);
	    if((Last > Buffer) && ('\n' == Last[-1]))
		{
		    --Last;
		}
	    if((Last > Buffer) && ('\r' == Last[-1]))
		{
		    --Last;
		}

	    /* Handle continued lines */
	    while((Last > Buffer) && ('\\' == Last[-1]))
		{
		    /* Strip off the backslash */
		    --Last;

		    /* Read next line by giving pointer to null-char as start for next */
		    Res = fgets(Last, (BUFFSIZE - (Last - Buffer)), InFile);
		    if(NULL == Res)
			{
			    if(feof(InFile))
				{
				    return NULL;	/* Return NULL on EOF */
				}
			    else
				{
				    printf(ERRTAG
					   "Unexpected error reading file\n");
				    exit(1);
				}
			}
		    ++(*LineNum);

		    /* Strip newline */
		    Last = Buffer + strlen(Buffer);
		    if((Last > Buffer) && ('\n' == Last[-1]))
			{
			    --Last;
			}
		    if((Last > Buffer) && ('\r' == Last[-1]))
			{
			    --Last;
			}
		}

	    /* Strip comment if any */
	    Cur = Buffer;
	    while(Cur < Last)
		{
		    if('#' == *Cur)
			{
			    Last = Cur;
			    break;
			}
		    ++Cur;
		}

	    /* Count tokens and find size */
	    assert(Last < (Buffer + BUFFSIZE));
	    Len = 0;
	    TokenCount = 0;
	    Cur = Buffer;
	    InToken = FALSE;
	    while(Cur < Last)
		{
		    if(InToken)
			{
			    if((' ' == *Cur) || ('\t' == *Cur))
				{
				    InToken = FALSE;
				}
			    else
				{
				    ++Len;
				}
			}
		    else
			{
			    if((' ' != *Cur) && ('\t' != *Cur))
				{
				    ++TokenCount;
				    ++Len;
				    InToken = TRUE;
				}
			}
		    ++Cur;	/* Advance pointer */
		}
	}
    while(0 == TokenCount);

    /* Find the size of mem to alloc. Use a contiguous block so is 
     * easy to deallocate */
    Len = (sizeof(char) * Len) +	/* Length of actual data */
	(sizeof(char) * TokenCount);	/* Null terminators */

    /* Alloc the pointer list and data list. Count the final 
     * empty string we will use as list terminator */
    Tokens = (char **)my_malloc(sizeof(char *) * (TokenCount + 1));
    *Tokens = (char *)my_malloc(sizeof(char) * Len);

    /* Copy tokens to result */
    Cur = Buffer;
    Dst = *Tokens;
    InToken = FALSE;
    CurToken = 0;
    while(Cur < Last)
	{
	    if(InToken)
		{
		    if((' ' == *Cur) || ('\t' == *Cur))
			{
			    InToken = FALSE;
			    *Dst = '\0';	/* Null term token */
			    ++Dst;
			    ++CurToken;
			}
		    else
			{
			    *Dst = *Cur;	/* Copy char */
			    ++Dst;
			}
		}
	    else
		{
		    if((' ' != *Cur) && ('\t' != *Cur))
			{
			    Tokens[CurToken] = Dst;	/* Set token start pointer */
			    *Dst = *Cur;	/* Copy char */
			    ++Dst;
			    InToken = TRUE;
			}
		}
	    ++Cur;		/* Advance pointer */
	}
    if(InToken)
	{
	    *Dst = '\0';	/* Null term final token */
	    ++Dst;
	    ++CurToken;
	}
    assert(CurToken == TokenCount);

    /* Set the final empty string entry */
    Tokens[CurToken] = NULL;

    /* Return the string list */
    return Tokens;
}

