/*
 * (C) Copyright Transarc Corporation 1989
 * Licensed Materials - Property of Transarc
 * All Rights Reserved.
 */

/*------------------------------------------------------------------------
 * textcb.c
 *
 * Implementation of the gator circular buffer package for its scrollable
 * text object.
 *
 *------------------------------------------------------------------------*/

#include <afs/param.h>
#include "gtxtextcb.h"		/*Module interface*/
#include <stdio.h>			/*Standard I/O stuff*/
#include <errno.h>

static int gator_textcb_debug;		/*Is debugging output turned on?*/

/*------------------------------------------------------------------------
 * gator_textcb_Init
 *
 * Description:
 *	Initialize the text circular buffer package.
 *
 * Arguments:
 *	a_debug : Should debugging output be turned on?
 *
 * Returns:
 *	Zero if successful,
 *	Error value otherwise.
 *
 * Environment:
 *	MUST BE THE FIRST ROUTINE CALLED FROM THIS PACKAGE.
 *
 * Side Effects:
 *	Just remembers if debugging output should be generated.
 *------------------------------------------------------------------------*/

int gator_textcb_Init(a_debug)
    int a_debug;

{ /*gator_textcb_Init*/

    static int initd;				/*Have we been called already?*/
    static char rn[] = "gator_textcb_Init";	/*Routine name*/

    if (initd) {
      fprintf(stderr, "[%s] Initialization routine called multiple times!!\n", rn);
      return(0);
    }
    else
      initd = 1;

    gator_textcb_debug = a_debug;
    return(0);

} /*gator_textcb_Init*/

/*------------------------------------------------------------------------
 * gator_textcb_Create
 *
 * Description:
 *	Create a new circular buffer.
 *
 * Arguments:
 *	int a_maxEntriesStored : How many entries should it have?
 *	int a_maxCharsPerEntry : Max chars in each entry.
 *
 * Returns:
 *	Ptr to the fully-initialized circular buffer hdr if successful,
 *	Null pointer otherwise.
 *
 * Environment:
 *	Makes sure the lock structure is properly initialized.
 *
 * Side Effects:
 *	As advertised; space is allocated for the circ buff.
 *------------------------------------------------------------------------*/

struct gator_textcb_hdr *gator_textcb_Create(a_maxEntriesStored, a_maxCharsPerEntry)
    int a_maxEntriesStored;
    int a_maxCharsPerEntry;

{ /*gator_textcb_Create*/

    static char rn[] = "gator_textcb_Create";	/*Routine name*/
    char *newBuff;				/*Ptr to new text buffer*/
    struct gator_textcb_entry *newEntries;	/*Ptr to new text entries*/
    struct gator_textcb_hdr *newHdr;		/*Ptr to new text hdr*/
    int bytesToAllocate;			/*Num bytes to allocate*/
    int numBuffBytes;				/*Num bytes in text buffer*/
    int curr_ent_num;				/*Current entry number*/
    struct gator_textcb_entry *curr_ent;	/*Ptr to current entry*/
    char *curr_buff;				/*Ptr to current buff pos*/
    int curr_inv;				/*Current inversion idx*/
    char *blankLine;				/*Ptr to blank line*/
    int i;					/*Loop variable*/

    /*
      * Start off by allocating the text buffer itself.  Don't forget we
      * need to allocate one more character per line, to make sure we can
      * always null-terminate them.  We also need to allocate the blank
      * line buffer.
      */
    numBuffBytes = bytesToAllocate = a_maxEntriesStored *
      (a_maxCharsPerEntry + 1);
    if (gator_textcb_debug)
      fprintf(stderr, "[%s] Allocating %d bytes for the text buffer\n", rn, bytesToAllocate);
    newBuff = (char *) malloc(bytesToAllocate);
    if (newBuff == (char *)0) {
      fprintf(stderr, "[%s] Can't allocate %d bytes for text buffer; errno is %d\n", rn, bytesToAllocate, errno);
      return((struct gator_textcb_hdr *)0);
    }
    else
      if (gator_textcb_debug)
	fprintf(stderr, "[%s] Text buffer allocated at 0x%x\n", rn, newBuff);
    blankLine = (char *) malloc(a_maxCharsPerEntry + 1);
    if (blankLine == (char *)0) {
      fprintf(stderr, "[%s] Can't allocate %d bytes for blank line buffer; errno is %d\n", rn, a_maxCharsPerEntry+1, errno);
      free(newBuff);
      return((struct gator_textcb_hdr *)0);
    }

    /*
      * Next, allocate the entry array.
      */
    bytesToAllocate = a_maxEntriesStored * sizeof(struct gator_textcb_entry);
    if (gator_textcb_debug)
      fprintf(stderr, "[%s] Allocating %d bytes for the %d text entry array items\n", rn, bytesToAllocate, a_maxEntriesStored);
    newEntries = (struct gator_textcb_entry *) malloc(bytesToAllocate);
    if (newEntries == (struct gator_textcb_entry *)0) {
      fprintf(stderr, "[%s] Can't allocate %d bytes for the %d-member text entry array; errno is %d\n", rn, bytesToAllocate, a_maxEntriesStored, errno);
      free(newBuff);
      free(blankLine);
      return((struct gator_textcb_hdr *)0);
    }
    else
      if (gator_textcb_debug)
	fprintf(stderr, "[%s] Text buffer entry array allocated at 0x%x\n", rn, newEntries);

    /*
      * Finish off by allocating the text circular buffer header.
      */
    bytesToAllocate = sizeof(struct gator_textcb_hdr);
    if (gator_textcb_debug)
      fprintf(stderr, "[%s] Allocating %d bytes for the text circular buffer header\n", rn, bytesToAllocate);
    newHdr = (struct gator_textcb_hdr *) malloc(bytesToAllocate);
    if (newHdr == (struct gator_textcb_hdr *)0) {
      fprintf(stderr, "[%s] Can't allocate %d bytes for text circular buffer header; errno is %d\n", rn, bytesToAllocate, errno);
      free(newBuff);
      free(blankLine);
      free(newEntries);
      return((struct gator_textcb_hdr *)0);
    }
    else
      if (gator_textcb_debug)
	fprintf(stderr, "[%s] Text circular buffer header allocated at 0x%x\n", rn, newHdr);

    /*
      * Now, just initialize all the pieces and plug them in.
      */
    if (gator_textcb_debug)
      fprintf(stderr, "[%s] Zeroing %d bytes in text buffer at 0x%x\n", rn, numBuffBytes, newBuff);
    bzero(newBuff, numBuffBytes);

    if (gator_textcb_debug)
      fprintf(stderr, "[%s] Initializing blank line buffer at 0x%x\n", rn, blankLine);
    for (i=0; i < a_maxCharsPerEntry; i++)
      *(blankLine+i) = ' ';
    *(blankLine+a_maxCharsPerEntry) = '\0';

    /*
      * Initialize each buffer entry.
      */
    for (curr_ent_num = 0, curr_buff = newBuff, curr_ent = newEntries;
	 curr_ent_num < a_maxEntriesStored;
	 curr_ent++, curr_ent_num++, curr_buff += (a_maxCharsPerEntry+1)) {
      if (gator_textcb_debug)
	fprintf(stderr, "[%s] Initializing buffer entry %d; its text buffer address is 0x%x\n", rn, curr_ent_num, curr_buff);
      curr_ent->ID	      = 0;
      curr_ent->highlight     = 0;
      curr_ent->numInversions = 0;
      curr_ent->charsUsed     = 0;
      curr_ent->textp	      = curr_buff;
      bcopy(blankLine, curr_ent->textp, a_maxCharsPerEntry+1);
      for (curr_inv = 0; curr_inv < GATOR_TEXTCB_MAXINVERSIONS; curr_inv++)
	   curr_ent->inversion[curr_inv] = 0;

    } /*Init each buffer entry*/

    if (gator_textcb_debug)
      fprintf(stderr, "[%s] Filling in circ buff header at 0x%x\n", rn, newHdr);
    Lock_Init(&(newHdr->cbLock));
    newHdr->maxEntriesStored  = a_maxEntriesStored;
    newHdr->maxCharsPerEntry  = a_maxCharsPerEntry;
    newHdr->currEnt	      = 0;
    newHdr->currEntIdx	      = 0;
    newHdr->oldestEnt	      = 0;
    newHdr->oldestEntIdx      = 0;
    newHdr->entry	      = newEntries;
    newHdr->blankLine	      = blankLine;

    /*
      * Finally, return the location of the new header.
      */
    return(newHdr);

} /*gator_textcb_Create*/

/*------------------------------------------------------------------------
 * bumpCB
 *
 * Description:
 *	Move down to the next circular buffer entry.
 *
 * Arguments:
 *	struct gator_textcb_hdr *a_cbhdr : Circ buff header to bump.
 *
 * Returns:
 *	Ptr to the newest current entry.
 *
 * Environment:
 *	Nothing interesting.
 *
 * Side Effects:
 *	As advertised.
 *------------------------------------------------------------------------*/

static struct gator_textcb_entry *bumpEntry(a_cbhdr)
    struct gator_textcb_hdr *a_cbhdr;

{ /*bumpEntry*/

    static char rn[] = "bumpEntry";		/*Routine name*/
    struct gator_textcb_entry *curr_ent;	/*Ptr to current entry*/
    int inv;					/*Inversion number*/

    /*
     * Bump the total number of writes, and don't forget to advance
     * the oldest entry, if appropriate.
     */
    if (gator_textcb_debug)
	  fprintf(stderr, "[%s]: Bumping entry for circular buffer at 0x%x; current values: currEnt=%d (idx %d), oldestEnt=%d (idx %d), maxEntriesStored=%d\n", rn, a_cbhdr, a_cbhdr->currEnt, a_cbhdr->currEntIdx, a_cbhdr->oldestEnt, a_cbhdr->oldestEntIdx, a_cbhdr->maxEntriesStored);

    a_cbhdr->currEnt++;
    if (++(a_cbhdr->currEntIdx) >= a_cbhdr->maxEntriesStored)
      a_cbhdr->currEntIdx = 0;
    curr_ent = a_cbhdr->entry + a_cbhdr->currEntIdx;

    if (gator_textcb_debug)
      fprintf(stderr, "[%s] Zeroing entry %d (idx %d) at 0x%x\n", rn, a_cbhdr->currEnt, a_cbhdr->currEntIdx, curr_ent);
    
    curr_ent->ID	    = a_cbhdr->currEnt;
    curr_ent->highlight	    = 0;
    curr_ent->numInversions = 0;
    curr_ent->charsUsed	    = 0;
    /*
      * Copy over a blank line into the one we're initializing.  We
      * copy over the trailing null, too.
      */
    bcopy(a_cbhdr->blankLine, curr_ent->textp, a_cbhdr->maxCharsPerEntry+1);
    for (inv=0; inv < GATOR_TEXTCB_MAXINVERSIONS; inv++)
      curr_ent->inversion[inv] = 0;

    /*
      * If we've already stated circulating in the buffer, remember to
      * bump the oldest entry info too.
      */
    if (a_cbhdr->currEnt >= a_cbhdr->maxEntriesStored) {
      if (gator_textcb_debug)
	fprintf(stderr, "[%s]: Advancing oldest entry number & index; was entry %d, index %d, now ", rn, a_cbhdr->oldestEnt, a_cbhdr->oldestEntIdx);
      a_cbhdr->oldestEnt++;
      if (++(a_cbhdr->oldestEntIdx) >= a_cbhdr->maxEntriesStored)
	a_cbhdr->oldestEntIdx = 0;
      if (gator_textcb_debug)
	fprintf(stderr, "entry %d, index %d\n", a_cbhdr->oldestEnt, a_cbhdr->oldestEntIdx);
    } /*Bump oldest entry info*/

    /*
      * Finally, return the address of the newest current entry.
      */
    return(curr_ent);

} /*bumpEntry*/

/*------------------------------------------------------------------------
 * gator_textcb_Write
 *
 * Description:
 *	Write the given string to the text circular buffer.  Line
 *	breaks are caused either by overflowing the current text
 *	line or via explicit '\n's.
 *
 * Arguments:
 *	struct gator_textcb_hdr *a_cbhdr : Ptr to circ buff hdr.
 *	char *a_textToWrite		 : Ptr to text to insert.
 *	int a_numChars			 : Number of chars to write.
 *	int a_highlight			 : Use highlighting?
 *	int a_skip;			 : Force a skip to the next line?
 *
 * Returns:
 *	Zero if successful,
 *	Error value otherwise.
 *
 * Environment:
 *	Circular buffer is consistent upon entry, namely the first and
 *	last entry pointers are legal.
 *
 * Side Effects:
 *	As advertised.
 *------------------------------------------------------------------------*/

int gator_textcb_Write(a_cbhdr, a_textToWrite, a_numChars, a_highlight, a_skip)
    struct gator_textcb_hdr *a_cbhdr;
    char *a_textToWrite;
    int a_numChars;
    int a_highlight;
    int a_skip;

{ /*gator_textcb_Write*/

    static char rn[] = "gator_textcb_Write";	/*Routine name*/
    struct gator_textcb_entry *curr_ent;	/*Ptr to current text entry*/
    int curr_ent_idx;				/*Index of current entry*/
    int max_chars;				/*Max chars per entry*/
    int chars_to_copy;				/*Num chars to copy in*/
    int effective_highlight;			/*Tmp highlight value*/
    char *dest;					/*Destination of char copy*/

    /*
      * Make sure we haven't been passed a bogus buffer, and lock it
      * before we start.
      */
    if (a_cbhdr == (struct gator_textcb_hdr *)0) {
      fprintf(stderr, "[%s]: Null pointer passed in for circ buff header!!  Aborting write operation.\n", rn);
      return(-1);
    }
    ObtainWriteLock(&(a_cbhdr->cbLock));

    curr_ent_idx	= a_cbhdr->currEntIdx;
    curr_ent		= (a_cbhdr->entry) + curr_ent_idx;
    max_chars		= a_cbhdr->maxCharsPerEntry;
    effective_highlight = curr_ent->highlight;
    if (curr_ent->numInversions % 2)
      effective_highlight = (effective_highlight ? 0 : 1);
    if (gator_textcb_debug)
      fprintf(stderr, "[%s]: Current entry: %d (at index %d, keeping %d max), effective highlight: %d, located at 0x%x\n", rn, a_cbhdr->currEnt, curr_ent_idx, a_cbhdr->maxEntriesStored, effective_highlight, curr_ent);

    while (a_numChars > 0) {
      /*
	* There are still characters to stuff into our circular buffer.
	*/
      if (gator_textcb_debug)
	fprintf(stderr, "[%s]: Top of write loop: %d char(s) left to write.\n", rn, a_numChars);

      if (curr_ent->charsUsed >= max_chars) {
	/*
	  * Bump the entry in the given circular buffer.
	  */
	if (gator_textcb_debug)
	  fprintf(stderr, "[%s]: Entry %d at index %d full, advancing to next one.\n", rn, a_cbhdr->currEnt, curr_ent_idx);	
	curr_ent = bumpEntry(a_cbhdr);
	curr_ent_idx = a_cbhdr->currEntIdx;
	if (gator_textcb_debug)
	  fprintf(stderr, "[%s] New CB entry info: currEnt=%d (idx %d), oldestEnt=%d (idx %d), curr entry ptr is 0x%x\n", rn, a_cbhdr->currEnt, a_cbhdr->currEntIdx, a_cbhdr->oldestEnt, a_cbhdr->oldestEntIdx, curr_ent);
      } /*Bump current entry*/

      /*
       * At this point, the current entry has room for at least one more
       * character, and we have at least one more character to write.
       * Insert as much from the user text as possible.
       */
      chars_to_copy = max_chars - curr_ent->charsUsed;
      if (a_numChars < chars_to_copy)
	chars_to_copy = a_numChars;
      dest = curr_ent->textp + curr_ent->charsUsed;
      if (gator_textcb_debug)
	fprintf(stderr, "[%s]: Copying %d char(s) into current entry at 0x%x (entry buffer starts at 0x%x)\n", rn, chars_to_copy, dest, curr_ent->textp);

      /*
	* Handle highlighting and inversions.
	*/
      if (curr_ent->charsUsed == 0) {
	/*
	  * No chars yet, so this sets the highlight field.
	  */
	effective_highlight = curr_ent->highlight = a_highlight;
      }
      else if (effective_highlight != a_highlight) {
	/*
	  * We need a new inversion, if there's room.
	  */
	if (gator_textcb_debug)
	  fprintf(stderr, "[%s]: Highlight mismatch, recording inversion at char loc %d\n", rn, curr_ent->charsUsed);
	if (curr_ent->numInversions < GATOR_TEXTCB_MAXINVERSIONS) {
	  effective_highlight = a_highlight;
	  curr_ent->inversion[curr_ent->numInversions] = curr_ent->charsUsed;
	  curr_ent->numInversions++;
	}
	else
	  if (gator_textcb_debug)
	    fprintf(stderr, "[%s]: Out of inversions!!\n", rn);
      } /*Handle inversion*/

      /*
	* Move the string chunk into its place in the buffer, bump the
	* number of chars used in the current entry.
	*/
      strncpy(dest, a_textToWrite, chars_to_copy);
      curr_ent->charsUsed += chars_to_copy;
      a_textToWrite	  += chars_to_copy;
      a_numChars	  -= chars_to_copy;

    } /*while (a_numChars > 0)*/

    /*
      * All characters have been copied in.  Handle the case where we've
      * been asked to skip to the next entry, even if there's still room
      * in the current one.
      */
    if (a_skip) {
      if (gator_textcb_debug)
	fprintf(stderr, "[%s] Handling request to skip to next entry\n", rn);
      if (curr_ent->charsUsed > 0)
	curr_ent = bumpEntry(a_cbhdr);
      else
	if (gator_textcb_debug)
	  fprintf(stderr, "[%s] Not skipping, we're already on a fresh entry\n", rn);
    } /*Skip to the next entry*/

    /*
      * We can now unlock the CB and return successfully.
      */
    ReleaseWriteLock(&(a_cbhdr->cbLock));
    return(0);

} /*gator_textcb_Write*/

/*------------------------------------------------------------------------
 * gator_textcb_BlankLine
 *
 * Description:
 *	Write out some number of blank lines to the given circular
 *	buffer.
 *
 * Arguments:
 *	struct gator_textcb_hdr *a_cbhdr : Ptr to circ buff hdr.
 *	int *a_numBlanks		 : Num. blank lines to write.
 *
 * Returns:
 *	Zero if successful,
 *	Error value otherwise.
 *
 * Environment:
 *	Circular buffer is consistent upon entry, namely the first and
 *	last entry pointers are legal.
 *
 * Side Effects:
 *	As advertised.
 *------------------------------------------------------------------------*/

int gator_textcb_BlankLine(a_cbhdr, a_numBlanks)
    struct gator_textcb_hdr *a_cbhdr;
    int a_numBlanks;

{ /*gator_textcb_BlankLine*/

    static char rn[] = "gator_textcb_BlankLine"; /*Routine name*/

    if (gator_textcb_debug)
      fprintf(stderr, "[%s] Putting out %d blank lines to the CB at 0x%x\n",
	      rn, a_numBlanks, a_cbhdr);

    if (a_cbhdr == (struct gator_textcb_hdr *)0) {
      if (gator_textcb_debug)
	fprintf(stderr, "[%s] Null pointer passed for CB hdr!!\n", rn);
      return(-1);
    }

    while (a_numBlanks > 0) {
      /*
	* The bumpEntry routine returns a struct gator_textcb_entry
	* pointer, but we don't need it here, so we don't assign it.
	*/
      bumpEntry(a_cbhdr);
      a_numBlanks--;
    }

    /*
      * Return happily and successfully.
      */
    return(0);

} /*gator_textcb_Write*/

/*------------------------------------------------------------------------
 * gator_textcb_Delete
 *
 * Description:
 *	Delete the storage used by the given circular buffer, including
 *	the header itself.
 *
 * Arguments:
 *	struct gator_textcb_hdr *a_cbhdr : Ptr to the header of the
 *						circ buffer to reap.
 *
 * Returns:
 *	Zero if successful,
 *	Error value otherwise.
 *
 * Environment:
 *	We write-lock the buffer before deleting it, which is slightly
 *	silly, since it will stop existing after we're done.  At least
 *	we'll make sure nobody is actively writing to it while it's
 *	being deleted.
 *
 * Side Effects:
 *	As advertised.
 *------------------------------------------------------------------------*/

int gator_textcb_Delete(a_cbhdr)
    struct gator_textcb_hdr *a_cbhdr;

{ /*gator_textcb_Delete*/

    static char rn[] = "gator_textcb_Delete";	/*Routine name*/

    if (gator_textcb_debug)
      fprintf(stderr, "[%s]: Deleting text circular buffer at 0x%x\n",
	      rn, a_cbhdr);
    ObtainWriteLock(&(a_cbhdr->cbLock));

    /*
      * The beginning of the text buffer itself is pointed to by the
      * first text entry.
      */
    if (gator_textcb_debug)
      fprintf(stderr, "[%s]: Freeing text buffer proper at 0x%x (%d bytes)\n",
	      rn, a_cbhdr->entry[0].textp,
	      (a_cbhdr->maxEntriesStored * a_cbhdr->maxCharsPerEntry));
    free(a_cbhdr->entry[0].textp);
    a_cbhdr->entry[0].textp = (char *)0;

    if (gator_textcb_debug)
      fprintf(stderr, "[%s]: Freeing text entry array at 0x%x (%d bytes)\n",
	      rn, a_cbhdr->entry,
	      (a_cbhdr->maxEntriesStored * sizeof(struct gator_textcb_entry)));
    free(a_cbhdr->entry);
    a_cbhdr->entry = (struct gator_textcb_entry *)0;
    free(a_cbhdr->blankLine);
    a_cbhdr->blankLine = (char *)0;

    /*
      * Release the write lock on it, then free the header itself.
      */
    ReleaseWriteLock(&(a_cbhdr->cbLock));
    if (gator_textcb_debug)
      fprintf(stderr, "[%s] Freeing cicular buffer header at 0x%x\n",
	      rn, a_cbhdr);
    free(a_cbhdr);
    return(0);

} /*gator_textcb_Delete*/