/*
 * Merge widget module
 *
 * At first, the base file is appended into @dtmap (draw_text()).
 * On each operation(insert, remove), inserted lines are inserted into @dtmap,
 * and also they are appended to an array of AddDispL.
 *
 * Copyright INOUE Seiichiro <inoue@ainet.or.jp>, licensed under the GPL.
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gtk/gtksignal.h>
#include <gtk/gtkvpaned.h>
#include "diff.h"
#include "gui.h"
#include "dtextmap.h"
#include "merge-widget.h"
#include "misc.h"
#include "gtktext-support.h"
#include "linenum.h"
#include "style.h"


/* Managed by merge->adl_array
   Added DispLines to basefile. */
typedef struct {
	int whichfile;
	DispLines *displn;	/* Not own, just refer */
} AddDispL;

/* Ideally, any file can be the basefile.
   But now there is a code which depends on basefile==FIRST_FILE. */
static WhichFile basefile = FIRST_FILE;
static WhichFile otherfile = SECOND_FILE;
static WhichFile otherfile2 = THIRD_FILE;/* ugly? */

static const char marktext[] = "$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$\n";/* character doesn't matter */
static const int marktext_lenb = sizeof(marktext)-1;


/* Private function declarations */
static void gdiff_merge_class_init(GdiffMergeClass *klass);
static void gdiff_merge_init(GdiffMerge *merge);
static void gdiff_merge_destroy(GtkObject *object);

static void gdiff_merge_display(GdiffBasePane *basepane);
static void gdiff_merge_show_linenum(GdiffBasePane *basepane, gboolean to_show);
static void gdiff_merge_select_dlines(GdiffBasePane *basepane, WhichFile whichfile, int ln);

static void guts_merge_display(GdiffMerge *merge);
static void draw_text(GdiffMerge *merge);
static void show_hide_numbers(GdiffMerge *merge, gboolean b_show);

static gint text_click_cb(GtkWidget *text, GdkEventButton *event, gpointer data);

static void guts_output_file(GdiffMerge *merge, const char *filename);

static void adl_add(GdiffMerge *merge, int i_adl, WhichFile whichfile, const DiffLines *dlines);
static void adl_remove(GdiffMerge *merge, int i_adl, WhichFile whichfile, const DiffLines *dlines);

static DispAttr map_dtype_to_attr(DiffType dtype, WhichFile whichfile);

static AddDispL* add_displn(GdiffMerge *merge, WhichFile whichfile, const DiffLines *dlines, int pos);
static int remove_displn(DTextMap *dtmap, GtkWidget *text, DispLines *displn);

static int adl_add_mark(GdiffMerge *merge, int i_adl, int cur_pos);
static int adl_remove_mark(GdiffMerge *merge, int i_adl);


static GdiffOnePaneClass *parent_class = NULL;


GtkType
gdiff_merge_get_type(void)
{
	static GtkType merge_type = 0;

	if (!merge_type) {
		static const GtkTypeInfo merge_info = {
			"GdiffMerge",
			sizeof(GdiffMerge),
			sizeof(GdiffMergeClass),
			(GtkClassInitFunc)gdiff_merge_class_init,
			(GtkObjectInitFunc)gdiff_merge_init,
			/* reserved_1 */ NULL,
			/* reserved_2 */ NULL,
			(GtkClassInitFunc)NULL,
		};
		merge_type = gtk_type_unique(GDIFF_TYPE_ONEPANE, &merge_info);
	}
  
	return merge_type;
}

static void
gdiff_merge_class_init(GdiffMergeClass *klass)
{
	GtkObjectClass *object_class;
	GdiffBasePaneClass *basepane_class;
	
	object_class = (GtkObjectClass*)klass;
	basepane_class = (GdiffBasePaneClass*)klass;
	parent_class = gtk_type_class(GDIFF_TYPE_ONEPANE);

	object_class->destroy = gdiff_merge_destroy;
	
	basepane_class->display = gdiff_merge_display;
	basepane_class->show_linenum = gdiff_merge_show_linenum;
	basepane_class->select_dlines = gdiff_merge_select_dlines;
}

static void
gdiff_merge_init(GdiffMerge *merge)
{
	GdiffOnePane *onepane;

	onepane = GDIFF_ONEPANE(merge);
	PANE_PREF(merge).view_type = NO_VIEW;
}

GtkWidget*
gdiff_merge_new(DiffDir *diffdir, DiffFiles *dfiles)
{
	GdiffMerge *merge;
	const FileInfo *fi1 = dfiles_get_fileinfo(dfiles, FIRST_FILE, TRUE);
	int dlines_len;
	int i;

	merge = gtk_type_new(GDIFF_TYPE_MERGE);

	_gdiff_basepane_set_backend(GDIFF_BASEPANE(merge), diffdir, dfiles);/*XXX*/
	
	/* Merge-pane specific internal data */
	dlines_len = g_list_length(dfiles->dlines_list);
	merge->adl_array = g_new(GSList*, dlines_len);
	for (i = 0; i < dlines_len; i++)
		merge->adl_array[i] = NULL;
	
	/* Merge-pane internal data derived from onepane */
	GDIFF_ONEPANE(merge)->dtmap = dtmap_new(fi1->nlines);
	if (dfiles->is_diff3)
		PANE_PREF(merge).view_type = MERGE3_VIEW;
	else
		PANE_PREF(merge).view_type = MERGE2_VIEW;

	gtk_signal_connect_after(GTK_OBJECT(GDIFF_ONEPANE(merge)->text),
							 "button_press_event",
							 GTK_SIGNAL_FUNC(text_click_cb), merge);

	/* workaround */
	gtk_widget_ensure_style(GDIFF_ONEPANE(merge)->text);

	/* Not implemented yet */
	PANE_PREF(merge).show_line_num = FALSE;
	
	guts_merge_display(merge);
	
	return GTK_WIDGET(merge);
}

static void
gdiff_merge_destroy(GtkObject *object)
{
	GdiffMerge *merge;
	int dlines_len;
	int i;

	g_return_if_fail(object != NULL);
	g_return_if_fail(GDIFF_IS_MERGE(object));

	merge = GDIFF_MERGE(object);
	/* free internal data */
	dlines_len = g_list_length(PANE_DFILES(GDIFF_BASEPANE(merge))->dlines_list);
	for (i = 0; i < dlines_len; i++) {
		GSList *list;
		for (list = merge->adl_array[i]; list; list = list->next) {
			g_free(list->data);
		}
		g_slist_free(merge->adl_array[i]);
	}
	g_free(merge->adl_array);

	if (GTK_OBJECT_CLASS(parent_class)->destroy)
		GTK_OBJECT_CLASS(parent_class)->destroy(object);
}


/** Interfaces **/
static void
gdiff_merge_display(GdiffBasePane *basepane)
{
	GdiffMerge *merge;

	g_return_if_fail(basepane != NULL);
	g_return_if_fail(GDIFF_IS_MERGE(basepane));

	merge = GDIFF_MERGE(basepane);

	guts_merge_display(merge);
}

/* Not implemented yet */
static void
gdiff_merge_show_linenum(GdiffBasePane *basepane, gboolean to_show)
{
	GdiffMerge *merge;

	g_return_if_fail(basepane != NULL);
	g_return_if_fail(GDIFF_IS_MERGE(basepane));

	merge = GDIFF_MERGE(basepane);

	/*
	if (to_show != PANE_PREF(merge).show_line_num) {
		show_hide_numbers(merge, to_show);
		PANE_PREF(merge).show_line_num = to_show;
	}
	*/
}

static void
gdiff_merge_select_dlines(GdiffBasePane *basepane, WhichFile whichfile, int ln)
{
	GdiffMerge *merge;
	DiffFiles *dfiles;
	const GList *dlines_node;

	g_return_if_fail(basepane != NULL);
	g_return_if_fail(GDIFF_IS_MERGE(basepane));

	merge = GDIFF_MERGE(basepane);
	dfiles = PANE_DFILES(merge);

	dlines_node = dfiles_find_includel(dfiles, whichfile, ln);
	if (dlines_node == NULL && ln == 1)
		dlines_node = dfiles_find_rel_curl(dfiles, whichfile, 0);/* exception */
	
	if (dlines_node) {
		/* todo coloring */

		GDIFF_BASEPANE(merge)->cur_dlines_node = dlines_node;
		gtk_signal_emit_by_name(GTK_OBJECT(merge), "move_diff", MOVED_CUR_NOSCROLL);
	}
}


void
gdiff_merge_insert_all(GdiffMerge *merge, WhichFile whichfile)
{
	DiffFiles *dfiles;
	GList *node;/* node of DiffLines list */
	GtkWidget *text;
	int i_adl;
	
	g_return_if_fail(merge != NULL);
	g_return_if_fail(GDIFF_IS_MERGE(merge));

	dfiles = PANE_DFILES(merge);
	text = GDIFF_ONEPANE(merge)->text;

	gtext_freeze(text);
	for (i_adl = 0, node = dfiles->dlines_list; node; node = node->next, i_adl++) {
		adl_add(merge, i_adl, whichfile, node->data);
	}
	gtext_thaw(text);
}

void
gdiff_merge_remove_all(GdiffMerge *merge, WhichFile whichfile)
{
	DiffFiles *dfiles;
	GList *node;/* node of DiffLines list */
	GtkWidget *text;
	int i_adl;
	
	g_return_if_fail(merge != NULL);
	g_return_if_fail(GDIFF_IS_MERGE(merge));

	dfiles = PANE_DFILES(merge);
	text = GDIFF_ONEPANE(merge)->text;

	gtext_freeze(text);
	for (i_adl = 0, node = dfiles->dlines_list; node; node = node->next, i_adl++) {
		adl_remove(merge, i_adl, whichfile, node->data);
	}
	gtext_thaw(text);
}


void
gdiff_merge_insert(GdiffMerge *merge, WhichFile whichfile)
{
	const GList *dlines_node;
	int i_adl;
	
	g_return_if_fail(merge != NULL);
	g_return_if_fail(GDIFF_IS_MERGE(merge));

	dlines_node = GDIFF_BASEPANE(merge)->cur_dlines_node;
	if (dlines_node == NULL)
		return;

	i_adl = g_list_position(PANE_DFILES(merge)->dlines_list, (GList*)dlines_node);
	adl_add(merge, i_adl, whichfile, dlines_node->data);
}

void
gdiff_merge_remove(GdiffMerge *merge, WhichFile whichfile)
{
	const GList *dlines_node;
	int i_adl;
	
	g_return_if_fail(merge != NULL);
	g_return_if_fail(GDIFF_IS_MERGE(merge));
	
	dlines_node = GDIFF_BASEPANE(merge)->cur_dlines_node;
	if (dlines_node == NULL)
		return;

	i_adl = g_list_position(PANE_DFILES(merge)->dlines_list, (GList*)dlines_node);
	adl_remove(merge, i_adl, whichfile, dlines_node->data);
}


void
gdiff_merge_output_file(GdiffMerge *merge, const char *filename)
{
	g_return_if_fail(merge != NULL);
	g_return_if_fail(GDIFF_IS_MERGE(merge));
	g_return_if_fail(filename != NULL && filename[0] != '\0');

	guts_output_file(merge, filename);
}



/** Internal functions **/
/**
 * guts_merge_display:
 * Show the diff result in merge.
 **/
static void
guts_merge_display(GdiffMerge *merge)
{
	draw_text(merge);

	if (PANE_PREF(merge).show_line_num == TRUE) {
		show_hide_numbers(merge, TRUE);
	}
}

/* difftype condition macros */
/* The basefile has the only portion */
#define IS_BASE_ONLY(dtype)	\
	((dtype & ONLY_ADD) && (dtype & F1ONLY))

/* The other file has the only portion, which means the basefile doesn't */
#define IS_OTHER_ONLY(dtype)	\
	(((dtype & ONLY_ADD) && (dtype & (F2ONLY|F3ONLY)))	\
	 || (dtype & F23ADD))

/* This file doesn't have a corresponding portion.
   It implies no need to take care of insert or remove. */
#define IS_NOT_THIS_O(dtype, whichfile)	\
	(((whichfile == SECOND_FILE)	\
		&& (((dtype & ONLY_ADD) && (dtype & (F1ONLY|F3ONLY))) || (dtype & F31ADD)))	\
	|| ((whichfile == THIRD_FILE)	\
		&& (((dtype & ONLY_ADD) && (dtype & (F1ONLY|F2ONLY))) || (dtype & F12ADD))))

/**
 * draw_text:
 * Draw the base file mainly.
 * The other files are managed internally.
 **/
static void
draw_text(GdiffMerge *merge)
{
	DiffFiles *dfiles = PANE_DFILES(merge);
	const FileInfo *fi = dfiles_get_fileinfo(dfiles, basefile, TRUE);
	const FileInfo *fi_o = dfiles_get_fileinfo(dfiles, otherfile, TRUE);
	const FileInfo *fi_o2 = dfiles_get_fileinfo(dfiles, otherfile2, TRUE);
	MBuffer *mbuf = PANE_MBUF(merge, basefile);
	const char *buf_pt;
	int buf_ln;
	int buf_lenb;
	DTextMap *dtmap = GDIFF_ONEPANE(merge)->dtmap;
	GtkWidget *text = GDIFF_ONEPANE(merge)->text;
	GdkFont *font = text->style->font;
	GList *node;/* node of DiffLines list */
	FontProp fprop;
	int oldpos = 0;
	int pos;
	int i_adl = 0;

	if (fi->buf == NULL && fi_o->buf == NULL && fi_o2->buf == NULL) /* Maybe, the file has been deleted. */
		return;

 	fprop.font = font;
	mbuf_goto_top(mbuf);
	gtext_freeze(text);
	for (node = dfiles->dlines_list; node; node = node->next, i_adl++) {
		const DiffLines *dlines = node->data;
		/* Use local variables for readability */
		int begin = dlines->between[basefile].begin;
		int end = dlines->between[basefile].end;
		DispAttr attr;
		int num_chars;

		fprop.fg = fprop.bg = NULL;
		buf_ln = mbuf->cur_ln;
		buf_pt = mbuf->cur_pt;
		buf_lenb = mbuf_goto_line(mbuf, begin) - buf_pt;
		pos = gtext_insert_buf(text, &fprop, buf_pt, mbuf->cur_pt - buf_pt);
		dtmap_append_displn(dtmap, DA_COMMON, oldpos, pos - oldpos,
							buf_pt, buf_lenb, begin - buf_ln);
		oldpos = pos;

		buf_pt = mbuf->cur_pt;
		if (end == 0) {/* special */
			g_assert(IS_OTHER_ONLY(dlines->difftype));
			dtmap_append_displn(dtmap, DA_O_ONLY|DA_O_ONLY_TOP, 0, 0, 0, 0, 0);
			/* mark here (after) */
			oldpos = adl_add_mark(merge, i_adl, oldpos);
			continue;
		} else {
			buf_lenb = mbuf_goto_line(mbuf, end + 1) - buf_pt;
		}

		if (IS_OTHER_ONLY(dlines->difftype)) {
			DispLines *displn;

			pos = gtext_insert_buf(text, &fprop, buf_pt, buf_lenb);
			attr = map_dtype_to_attr(dlines->difftype, basefile);
			displn = dtmap_append_displn(dtmap, attr, oldpos, pos - oldpos,
										 buf_pt, buf_lenb, end+1 - begin);
			/* mark here (after) */
			oldpos = adl_add_mark(merge, i_adl, pos);
		} else {
			AddDispL *adl;
			DispLines *displn;

			/* mark here (before) */
			oldpos = adl_add_mark(merge, i_adl, oldpos);

			attr = map_dtype_to_attr(dlines->difftype, basefile);
			num_chars = get_num_chars(buf_pt, buf_lenb, !GTK_TEXT(text)->use_wchar);
			displn = dtmap_append_displn(dtmap, attr|DA_HIDE, oldpos, num_chars,
										 buf_pt, buf_lenb, end+1 - begin);
			dtmap->total_nl -= (end+1 - begin);/* Hidden lines */

			adl = g_new(AddDispL, 1);
			adl->whichfile = basefile;
			adl->displn = displn;
			merge->adl_array[i_adl] = g_slist_append(merge->adl_array[i_adl], adl);
		}
	}
	/* Draw the remained part */
	fprop.fg = fprop.bg = NULL;
	buf_ln = mbuf->cur_ln;
	buf_pt = mbuf->cur_pt;
	buf_lenb = mbuf_goto_line(mbuf, fi->nlines + 1) - buf_pt;
	pos = gtext_insert_buf(text, &fprop, buf_pt, buf_lenb);
	dtmap_append_displn(dtmap, DA_COMMON, oldpos, pos - oldpos,
						buf_pt, buf_lenb, fi->nlines+1 - buf_ln);
	gtext_thaw(text);
}


/**
 * show_hide_numbers:
 * Show(or hide) line numbers on the head of each lines.
 **/
static void
show_hide_numbers(GdiffMerge *merge, gboolean b_show)
{
	/*XXX TODO*/
}

/**
 * text_click_cb:
 * Signal handler for button_click on text widget.
 * This is connected after default handler,
 * so I can get the clicked position (point in text widget term).
 * Calculate line number from the point,
 * and map it to line number on the buffer.
 **/
static gint
text_click_cb(GtkWidget *text, GdkEventButton *event, gpointer data)
{
	GdiffMerge *merge = data;
	DiffFiles *dfiles = PANE_DFILES(merge);
	DTextMap *dtmap = GDIFF_ONEPANE(merge)->dtmap;

	if (event->button == 1) {
		const GList *dlines_node;
		int index, tln, bln;

		index = gtext_get_cursor_pos(text);
		tln = gtext_line_from_index(text, index);
		bln = dtmap_map_t2b(dtmap, tln);
#ifdef DEBUG
		g_print("tln=%d, bln=%d\n", tln, bln);
#endif
		dlines_node = dfiles_find_includel(dfiles, basefile, bln);
		if (dlines_node == NULL && bln == 1)
			dlines_node = dfiles_find_rel_curl(dfiles, basefile, 0);/* exception */

		if (dlines_node) {
			gtk_signal_emit_by_name(GTK_OBJECT(merge), "select_dlines",
									basefile, bln);
		}
	}

	return FALSE;
}

static void
guts_output_file(GdiffMerge *merge, const char *filename)
{
	DTextMap *dtmap = GDIFF_ONEPANE(merge)->dtmap;
	DispLines *displn;
	FILE *fp = NULL;

	fp = fopen(filename, "w");
	if (fp == NULL) {
		g_message("can't write to %s\n", filename);
		return;
	}

	for (displn = dtmap_first_displn(dtmap, DA_ANY); displn; displn = dtmap_next_displn(dtmap, DA_ANY)) {
		const char *buf_pt;
		
		if (displn->attr & DA_HIDE)
			continue;
		if (displn->attr & DA_MARK)
			continue;
		
		buf_pt = mbuf_goto_top(MBUFFER(displn));
		fwrite(buf_pt, mbuf_goto_bottom(MBUFFER(displn)) - buf_pt, 1, fp);
	}
	if (fp)
		fclose(fp);
}

/**
 * adl_add:
 * Add the portion of @whichfile into text widget.
 * The inserted portion is managed by GSList *merge->adl_array[i_adl].
 **/
static void
adl_add(GdiffMerge *merge, int i_adl, WhichFile whichfile, const DiffLines *dlines)
{
	MBuffer *mbuf = PANE_MBUF(merge, whichfile);
	DTextMap *dtmap = GDIFF_ONEPANE(merge)->dtmap;
	GtkWidget *text = GDIFF_ONEPANE(merge)->text;
	GSList *list;
	AddDispL *adl;
	DispLines *displn;
	FontProp fprop;
	const char *buf_pt;
	int buf_lenb;
	int begin = dlines->between[whichfile].begin;
	int end = dlines->between[whichfile].end;
	int pos;

	if (whichfile == basefile && IS_OTHER_ONLY(dlines->difftype))
		return;
	if (whichfile != basefile && IS_BASE_ONLY(dlines->difftype))
		return;
	if (whichfile != basefile && IS_NOT_THIS_O(dlines->difftype, whichfile))
		return;
	
	fprop.font = text->style->font;
	fprop.fg = &PANE_PREF(merge).diff_fg[whichfile];
	fprop.bg = &PANE_PREF(merge).diff_bg[whichfile];
	
	gtext_freeze(text);
	pos = adl_remove_mark(merge, i_adl);

	if (IS_OTHER_ONLY(dlines->difftype)) {
		for (list = merge->adl_array[i_adl]; list; list = list->next) {
			adl = list->data;
			if (adl->whichfile == whichfile) {/* already exist */
				goto done;
			}
		}

		if (merge->adl_array[i_adl]) {/* append the list */
			GSList *last;

			last = g_slist_last(merge->adl_array[i_adl]);
			displn = ((AddDispL*)last->data)->displn;
			pos = displn->pos + displn->len;
		} else {/* no list in here, which means no inserted portions */
			/* pos is taken from the mark abobe */
			g_assert(pos != -1);
		}
		adl = add_displn(merge, whichfile, dlines, pos);
		merge->adl_array[i_adl] = g_slist_append(merge->adl_array[i_adl], adl);
	} else {
		if (whichfile == basefile) {
			/* look for a hidden one */
			for (list = merge->adl_array[i_adl]; list; list = list->next) {
				adl = list->data;
				displn = adl->displn;
				if (displn->attr & DA_HIDE) {
					g_assert(adl->whichfile == basefile);
					gtext_set_point(text, displn->pos);
					buf_pt = mbuf_goto_line(mbuf, begin);
					buf_lenb = mbuf_goto_line(mbuf, end + 1) - buf_pt;
					gtext_insert_buf(text, &fprop, buf_pt, buf_lenb);
					/* hack to show */
					dtmap_show_displn(dtmap, displn);
					break;
				}
			}
		} else {
			GSList *last = NULL;/* the node related to the last shown portion */
			int last_pos = 0;

			for (list = merge->adl_array[i_adl]; list; list = list->next) {
				adl = list->data;
				if (adl->whichfile == whichfile) {/* already exist */
					goto done;
				}
			}

			/* look for the last shown portion */
			for (list = merge->adl_array[i_adl]; list; list = list->next, last_pos++) {
				adl = list->data;
				displn = adl->displn;
				if (displn->attr & DA_HIDE) {
					continue;
				}
				last = list;
			}
			if (last) {
				displn = ((AddDispL*)last->data)->displn;
				pos = displn->pos + displn->len;
				adl = add_displn(merge, whichfile, dlines, pos);
				merge->adl_array[i_adl] = g_slist_append(merge->adl_array[i_adl], adl);
			} else {/* implies a hidden one exists */
				list = merge->adl_array[i_adl];
				g_assert(list);
				displn = ((AddDispL*)list->data)->displn;
				g_assert(displn->attr & DA_HIDE);
				
				pos = displn->pos;
				adl = add_displn(merge, whichfile, dlines, pos);
				merge->adl_array[i_adl] = g_slist_prepend(merge->adl_array[i_adl], adl);
			}
		}
	}
	
 done:
	gtext_thaw(text);
}


/**
 * adl_remove:
 * Remove the inserted portion of @whichfile from text widget.
 * The inserted portion is managed by GSList *merge->adl_array[i_adl].
 **/
static void
adl_remove(GdiffMerge *merge, int i_adl, WhichFile whichfile, const DiffLines *dlines)
{
	DTextMap *dtmap = GDIFF_ONEPANE(merge)->dtmap;
	GtkWidget *text = GDIFF_ONEPANE(merge)->text;
	GSList *list;
	AddDispL *adl;
	DispLines *displn;
	int pos = -1;
	int num_shown;

	if (whichfile == basefile && IS_OTHER_ONLY(dlines->difftype))
		return;
	if (whichfile != basefile && IS_BASE_ONLY(dlines->difftype))
		return;
	if (whichfile != basefile && IS_NOT_THIS_O(dlines->difftype, whichfile))
		return;

	gtext_freeze(text);

	/* look for the current one */
	for (list = merge->adl_array[i_adl]; list; list = list->next) {
		adl = list->data;
		if (adl->whichfile == whichfile) {/* already there */
			displn = adl->displn;
			if (displn->attr & DA_HIDE) {
				goto done;
			} else {
				if (whichfile == basefile) {
					pos = displn->pos;
					gtext_set_point(text, pos);
					gtext_forward_delete(text, displn->len);
					/* hack to hide */
					dtmap_hide_displn(dtmap, displn);
				} else {
					pos = remove_displn(dtmap, text, displn);
					g_free(adl);
					merge->adl_array[i_adl] = g_slist_remove(merge->adl_array[i_adl], adl);
				}
				break;
			}
		}
	}

	/* If no portion is added, add a mark */
	num_shown = 0;
	if (IS_OTHER_ONLY(dlines->difftype)) {
		if (merge->adl_array[i_adl] == NULL) {
			if (dlines->between[basefile].end == 0)
				dtmap_append_displn(dtmap, DA_O_ONLY|DA_O_ONLY_TOP, 0, 0, 0, 0, 0);
			adl_add_mark(merge, i_adl, pos);
		} else {
			pos = -1;/* for a strict check */
			for (list = merge->adl_array[i_adl]; list; list = list->next) {
				adl = list->data;
				displn = adl->displn;
				if (displn->attr & DA_O_ONLY) {
					pos = displn->pos + displn->len;
					continue;
				}
				num_shown++;
			}
			if (num_shown == 0) {
				g_assert(pos != -1);
				adl_add_mark(merge, i_adl, pos);
			}
		}
	} else {
		if (merge->adl_array[i_adl] == NULL) {
			adl_add_mark(merge, i_adl, pos);
		} else {
			for (list = merge->adl_array[i_adl]; list; list = list->next) {
				adl = list->data;
				displn = adl->displn;
				if (displn->attr & DA_HIDE) {
					pos = displn->pos;
					continue;
				}
				num_shown++;
			}
			if (num_shown == 0) {
				adl_add_mark(merge, i_adl, pos);				
			}
		}
	}

 done:
	gtext_thaw(text);
}

static DispAttr
map_dtype_to_attr(DiffType dtype, WhichFile whichfile)
{
	if (dtype == CHANGE)
		return whichfile == basefile ? DA_CHANGE : DA_CHANGE_O;
	else if (dtype & F1ONLY)
		return DA_ONLY;
	else if (dtype & F2ONLY)
		return whichfile == basefile ? DA_O_ONLY : DA_ONLY_O;
	else if (dtype & F3ONLY)
		return whichfile == basefile ? DA_O2_ONLY : DA_ONLY_O2;/* XXX: Need? */
	else if (dtype == F12ADD || dtype == F31ADD)
		return whichfile == basefile ? DA_CHANGE : DA_CHANGE_O;
	else if (dtype == F23ADD)
		return whichfile == basefile ? DA_O_ONLY : DA_ONLY_O;

	g_assert_not_reached();
	return 0;
}


/* Add the diff portion to text widget.
 * Allocate AddDislL and return it.
 * The returned AddDislL will be inserted to GSList *merge->adl_array[i_adl]. */
static AddDispL*
add_displn(GdiffMerge *merge, WhichFile whichfile, const DiffLines *dlines, int pos)
{
	MBuffer *mbuf = PANE_MBUF(merge, whichfile);
	DTextMap *dtmap = GDIFF_ONEPANE(merge)->dtmap;
	GtkWidget *text = GDIFF_ONEPANE(merge)->text;
	DispLines *displn;
	FontProp fprop;
	int begin = dlines->between[whichfile].begin;
	int end = dlines->between[whichfile].end;
	AddDispL* adl;
	const char *buf_pt;
	int buf_lenb;
	int newpos;
	DispAttr attr;
	
	fprop.font = text->style->font;
	fprop.fg = &PANE_PREF(merge).diff_fg[whichfile];
	fprop.bg = &PANE_PREF(merge).diff_bg[whichfile];

	adl = g_new(AddDispL, 1);
	adl->whichfile = whichfile;
	
	buf_pt = mbuf_goto_line(mbuf, begin);
	buf_lenb = mbuf_goto_line(mbuf, end + 1) - buf_pt;
	gtext_set_point(text, pos);
	newpos = gtext_insert_buf(text, &fprop, buf_pt, buf_lenb);
	attr = map_dtype_to_attr(dlines->difftype, whichfile);
	displn = dtmap_insert_displn(dtmap, attr, pos, newpos - pos,
								 buf_pt, buf_lenb, end+1 - begin);
	adl->displn = displn;

	return adl;
}

/* Remove the lines related to @displn from text widget.
   Also remove its data from the internal data, dtmap. */
static int
remove_displn(DTextMap *dtmap, GtkWidget *text, DispLines *displn)
{
	int pos;
	
	pos = displn->pos;
	gtext_set_point(text, pos);
	gtext_forward_delete(text, displn->len);
	dtmap_remove_displn(dtmap, displn);

	return pos;
}


/* Add a mark to text widget.
 * The added mark is also inserted to GSList *merge->adl_array[i_adl]. */
static int
adl_add_mark(GdiffMerge *merge, int i_adl, int cur_pos)
{
	DTextMap *dtmap = GDIFF_ONEPANE(merge)->dtmap;
	GSList *list;
	AddDispL *adl;
	GtkWidget *text = GDIFF_ONEPANE(merge)->text;
	FontProp fprop;
	int pos;

	for (list = merge->adl_array[i_adl]; list; list = list->next) {
		adl = list->data;
		if (adl->whichfile == -1) {/* mark is found */
			return -1;
		}
	}
	
 	fprop.font = text->style->font;
	fprop.fg = fprop.bg = &GTK_WIDGET(text)->style->bg[GTK_STATE_INSENSITIVE];
	
	adl = g_new(AddDispL, 1);
	adl->whichfile = -1;
	
	gtext_set_point(text, cur_pos);
	pos = gtext_insert_buf(text, &fprop, marktext, marktext_lenb);
	adl->displn = dtmap_insert_displn(dtmap, DA_MARK, cur_pos, pos - cur_pos,
									  marktext, marktext_lenb, 1);
	merge->adl_array[i_adl] = g_slist_append(merge->adl_array[i_adl], adl);

	return pos;
}

/* Remove the mark from text widget
 * The inserted mark is managed by GSList of AddDispL. */
static int
adl_remove_mark(GdiffMerge *merge, int i_adl)
{
	DTextMap *dtmap = GDIFF_ONEPANE(merge)->dtmap;
	GtkWidget *text = GDIFF_ONEPANE(merge)->text;
	GSList *list;
	AddDispL *adl;
	int pos;
	
	for (list = merge->adl_array[i_adl]; list; list = list->next) {
		adl = list->data;
		if (adl->whichfile == -1) {/* found the mark */
			pos = remove_displn(dtmap, text, adl->displn);
			g_free(adl);
			merge->adl_array[i_adl] = g_slist_remove(merge->adl_array[i_adl], adl);
			return pos;
		}
	}
	return -1;
}