// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF
// ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO
// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
// PARTICULAR PURPOSE.
//
// Copyright (c) Microsoft Corporation. All rights reserved.

/*
 * line.cpp
 *
 * data type representing a string of ascii text along with a line number.
 * a LINE can compare itself to another line, and maintain a link if the
 * lines are similar. A line can also generate a hashcode for the line.
 *
 * Comparisons between lines take note of the global option flag
 * ignore_blanks, defined elsewhere. If this is true, we ignore
 * differences in spaces and tabs when comparing lines, and when
 * generating hashcodes.
 *
 * Links and hashcodes are only generated once. to clear the link and
 * force re-generation of the hashcode (eg after changing ignore_blanks)
 * call line_reset.
 *
 * Lines can be allocated on a list. If a null list handle is passed, the
 * line will be allocated using HeapAlloc(). 
 *
 */

#include "precomp.h"

#include "sdkdiff.h"    /* defines hHeap and ignore_blanks */
#include "list.h"
#include "line.h"

#define IS_BLANK(c) \
    (((c) == ' ') || ((c) == '\t') || ((c) == '\r'))

/* flag values (or-ed) */
#define LF_DISCARD      1       /* if true, alloced using HeapAlloc */
#define LF_HASHVALID    2       /* if true, hashcode need not be recalced */


/*
 * create a new line. make a copy of the text.
 *
 * if the list is non-null, allocate on the list. if null, alloc using
 * HeapAlloc.
 */
LINE
line_new(LPSTR text, int linelength, LPWSTR pwzText, int cwchText, UINT linenr, LIST list)
{
    LINE line;
    int cch = 0;

    /* alloc a line. from the list if there is a list */
    if (list) {
        line = (LINE)List_NewLast(list, sizeof(struct fileline));
        if (line == NULL) {
            return(NULL);
        }
        line->flags = 0;
    } else  {
        line = (LINE) HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(struct fileline));
        if (line == NULL) {
            return(NULL);
        }
        line->flags = LF_DISCARD;
    }

    /* alloc space for the text. remember the null character */
    /* also add cr/nl pair if absent for composite file */
    cch = (text[linelength - 1] == '\n') ? 1 : 3;
    line->text = (char*)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, linelength + cch);
    if (line->text == NULL)
    {
        return NULL;
    }
    My_mbsncpy(line->text, text, linelength);
    if (cch == 3) {
        line->text[linelength++] = '\r';
        line->text[linelength++] = '\n';
    }
    line->text[linelength] = '\0';

    line->pwzText = 0;
    if (pwzText) 
    {
        /* alloc space for the unicode text. remember the null character */
        /* also add cr/nl pair if absent for composite file */
        cch = (pwzText[cwchText - 1] == '\n') ? 1 : 3;
        line->pwzText = (WCHAR*)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, (cwchText + cch) * sizeof(*pwzText));
        if (line->pwzText == NULL)
        {
            return NULL;
        }
        StringCchCopyNW(line->pwzText,cwchText+cch,pwzText, cwchText);
        if (cch == 3) {
            line->pwzText[cwchText++] = '\r';
            line->pwzText[cwchText++] = '\n';
        }
        line->pwzText[cwchText] = '\0';
    }

    line->link = NULL;
    line->linenr = linenr;

    return(line);
}

/*
 * delete a line. free up all associated memory and if the line
 * was not alloc-ed from a list, free up the line struct itself
 */
void
line_delete(LINE line)
{
    if (line == NULL) {
        return;
    }

    /* free up text space */
    HeapFree(GetProcessHeap(), NULL, line->text);

    /* free up line itself only if not on list */
    if (line->flags & LF_DISCARD) {
        HeapFree(GetProcessHeap(), NULL, (LPSTR) line);
    }
}

/*
 * clear the link and force recalc of the hash code.
 */
void
line_reset(LINE line)
{
    if (line == NULL) {
        return;
    }

    line->link = NULL;

    line->flags &= ~LF_HASHVALID;
}


/* return a pointer to the line text */
LPSTR
line_gettext(LINE line)
{
    if (line == NULL) {
        return(NULL);
    }

    return(line->text);
}

/* return a pointer to the line text */
LPWSTR
line_gettextW(LINE line)
{
    if (line == NULL) {
        return(NULL);
    }

    return(line->pwzText);
}

/* get the effective text length, ignoring blanks */
int line_gettextlen(LINE line)
{
    int sum = 0;
    LPSTR string = line->text;

    while (*string != '\0') {

        if (ignore_blanks) {
            while (IS_BLANK(*string)) {
                string++;
            }
        }
        if (IsDBCSLeadByte((BYTE)*string)) {
            ++sum;
            ++string;
        }
        ++sum;
        ++string;
    }
    return(sum);
}


/*
 * line_gettabbedlength
 *
 * return length of line in characters, expanding tabs. useful
 * for display-space calculations.
 */
int
line_gettabbedlength(LINE line, int tabstops)
{
    int length;
    LPSTR chp;

    if (line == NULL) {
        return(0);
    }

    for (length = 0, chp = line->text; *chp != '\0'; chp++) {
        if (*chp == '\t') {
            length = (length + tabstops) / tabstops * tabstops;
        } else {
            if (IsDBCSLeadByte(*chp)) {
                chp++;
                length++;
            }
            length++;
        }
    }
    return(length);
}


/* return the hashcode for this line */
DWORD
line_gethashcode(LINE line)
{
    if (line == NULL) {
        return(0);
    }

    if (! (line->flags & LF_HASHVALID)) {
        /* hashcode needs to be recalced */
        line->hash = hash_string(line->text, ignore_blanks);
        line->flags |= LF_HASHVALID;
    }
    return(line->hash);
}

/* return the handle for the line that is linked to this line (the
 * result of a successful line_link() operation). This line is
 * identical in text to the linked line (allowing for ignore_blanks).
 */
LINE
line_getlink(LINE line)
{
    if (line == NULL) {
        return(NULL);
    }

    return(line->link);
}

/* return the line number associated with this line */
UINT
line_getlinenr(LINE line)
{
    if (line == NULL) {
        return(0);
    }

    return(line->linenr);
}

/* compare two lines. return TRUE if they are the same. uses
 * ignore_blanks to determine whether to ignore any
 * spaces/tabs in the comparison.
 */
BOOL
line_compare(LINE line1, LINE line2)
{
    LPSTR p1, p2;

    if ((line1 == NULL) || (line2 == NULL)) {
        /* null line handles do not compare */
        return(FALSE);
    }

    /* check that the hashcodes match */
    if (line_gethashcode(line1) != line_gethashcode(line2)) {
        return(FALSE);
    }

    /* hashcodes match - are the lines really the same ? */
    /* note that this is coupled to gutils\utils.c in definition of blank */
    p1 = line_gettext(line1);
    p2 = line_gettext(line2);
    do {
        if (ignore_blanks) {
            while (IS_BLANK(*p1)) {
                p1 = CharNext(p1);
            }
            while (IS_BLANK(*p2)) {
                p2 = CharNext(p2);
            }
        }
        if (IsDBCSLeadByte(*p1) && *(p1+1) != '\0'
            &&  IsDBCSLeadByte(*p2) && *(p2+1) != '\0') {
            if (*p1 != *p2 || *(p1+1) != *(p2+1)) {
                return(FALSE);
            }
            p1 += 2;
            p2 += 2;
        } else {
            if (*p1 != *p2) {
                return(FALSE);
            }
            p1++;
            p2++;
        }
    } while ( (*p1 != '\0') && (*p2 != '\0'));

    return(TRUE);
}

/*
 * attempt to link two lines. return TRUE if succesful.
 *
 * this will fail if either line is NULL, or already linked, or if
 * they differ.
 */
BOOL
line_link(LINE line1, LINE line2)
{
    if ( (line1 == NULL) || (line2 == NULL)) {
        return(FALSE);
    }

    if ( (line1->link != NULL) || (line2->link != NULL)) {
        return(FALSE);
    }

    if (line_compare(line1, line2)) {
        line1->link = line2;
        line2->link = line1;
        return(TRUE);
    } else {
        return(FALSE);
    }
}


/* return TRUE iff line is blank.  NULL => return FALSE */
BOOL line_isblank(LINE line)
{
    return line!=NULL && utils_isblank(line->text);
}