/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 *  Copyright (C) 2000 Helix Code Inc.
 *
 *  Authors: Michael Zucchi <notzed@helixcode.com>
 *
 *  This program is free software; you can redistribute it and/or 
 *  modify it under the terms of the GNU General Public License as 
 *  published by the Free Software Foundation; either version 2 of the
 *  License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 *  USA
 */

/* TODO: This could probably be made a camel object, but it isn't really required */

#include <config.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <glib.h>
#include <ctype.h>

#include "camel-folder-thread.h"
#include "e-util/e-memory.h"

#define d(x)

#define TIMEIT

#ifdef TIMEIT
#include <sys/time.h>
#include <unistd.h>
#endif

static void
container_add_child(CamelFolderThreadNode *node, CamelFolderThreadNode *child)
{
	d(printf("\nAdding child %p to parent %p \n", child, node));
	child->next = node->child;
	node->child = child;
	child->parent = node;
}

static void
container_parent_child(CamelFolderThreadNode *parent, CamelFolderThreadNode *child)
{
	CamelFolderThreadNode *c, *node;

	/* are we already the right parent? */
	if (child->parent == parent)
		return;

	/* are we unparented? */
	if (child->parent == NULL) {
		container_add_child(parent, child);
		return;
	}

	/* else remove child from its existing parent, and reparent */
	node = child->parent;
	c = (CamelFolderThreadNode *)&node->child;
	d(printf("scanning children:\n"));
	while (c->next) {
		d(printf(" %p\n", c));
	        if (c->next==child) {
			d(printf("found node %p\n", child));
			c->next = c->next->next;
			child->parent = NULL;
			container_add_child(parent, child);
			return;
		}
		c = c->next;
	}

	printf("DAMN, we shouldn't  be here!\n");
}

static void
prune_empty(CamelFolderThread *thread, CamelFolderThreadNode **cp)
{
	CamelFolderThreadNode *child, *next, *c, *lastc;

	/* yes, this is intentional */
	lastc = (CamelFolderThreadNode *)cp;
	while (lastc->next) {
		c = lastc->next;

		d(printf("checking message %p %p (%08x%08x)\n", c,
			 c->message, c->message?c->message->message_id.id.part.hi:0,
			 c->message->message_uid.id.part.lo:0));
		if (c->message == NULL) {
			if (c->child == NULL) {
				d(printf("removing empty node\n"));
				lastc->next = c->next;
				e_memchunk_free(thread->node_chunks, c);
				continue;
			}
			if (c->parent || c->child->next==0) {
				d(printf("promoting child\n"));
				lastc->next = c->next; /* remove us */
				child = c->child;
				while (child) {
					next = child->next;

					child->parent = c->parent;
					child->next = lastc->next;
					lastc->next = child;

					child = next;
				}
				continue;
			}
		}
		prune_empty(thread, &c->child);
		lastc = c;
	}
}

static void
hashloop(void *key, void *value, void *data)
{
	CamelFolderThreadNode *c = value;
	CamelFolderThreadNode *tail = data;

	if (c->parent == NULL) {
		c->next = tail->next;
		tail->next = c;
	}
}

static char *
get_root_subject(CamelFolderThreadNode *c, int *re)
{
	char *s, *p;
	CamelFolderThreadNode *scan;
	
	s = NULL;
	*re = FALSE;
	if (c->message)
		s = (char *)camel_message_info_subject(c->message);
	else {
		/* one of the children will always have a message */
		scan = c->child;
		while (scan) {
			if (scan->message) {
				s = (char *)camel_message_info_subject(scan->message);
				break;
			}
			scan = scan->next;
		}
	}
	if (s != NULL) {
		while (*s) {
			while (isspace(*s))
				s++;
			if (s[0] == 0)
				break;
			if ((s[0] == 'r' || s[0]=='R')
			    && (s[1] == 'e' || s[1]=='E')) {
				p = s+2;
				while (isdigit(*p) || (ispunct(*p) && (*p != ':')))
					p++;
				if (*p==':') {
					*re = TRUE;
					s = p+1;
				} else
					break;
			} else
				break;
		}
		if (*s)
			return s;
	}
	return NULL;
}

/* this can be pretty slow, but not used often */
/* clast cannot be null */
static void
remove_node(CamelFolderThreadNode **list, CamelFolderThreadNode *node, CamelFolderThreadNode **clast)
{
	CamelFolderThreadNode *c;

	/* this is intentional, even if it looks funny */
	/* if we have a parent, then we should remove it from the parent list,
	   otherwise we remove it from the root list */
	if (node->parent) {
		c = (CamelFolderThreadNode *)&node->parent->child;
	} else {
		c = (CamelFolderThreadNode *)list;
	}
	while (c->next) {
		if (c->next == node) {
			if (*clast == c->next)
				*clast = c;
			c->next = c->next->next;
			return;
		}
		c = c->next;
	}

	printf("ERROR: removing node %p failed\n", node);
}

static void
group_root_set(CamelFolderThread *thread, CamelFolderThreadNode **cp)
{
	GHashTable *subject_table = g_hash_table_new(g_str_hash, g_str_equal);
	CamelFolderThreadNode *c, *clast, *scan, *container;

	/* gather subject lines */ 
	d(printf("gathering subject lines\n"));
	clast = (CamelFolderThreadNode *)cp;
	c = clast->next;
	while (c) {
		c->root_subject = get_root_subject(c, &c->re);
		if (c->root_subject) {
			container = g_hash_table_lookup(subject_table, c->root_subject);
			if (container == NULL
			    || (container->message == NULL && c->message)
			    || (container->re == TRUE && !c->re)) {
				g_hash_table_insert(subject_table, c->root_subject, c);
			}
		}
		c = c->next;
	}

	/* merge common subjects? */
	clast = (CamelFolderThreadNode *)cp;
	while (clast->next) {
		c = clast->next;
		d(printf("checking %p %s\n", c, c->root_subject));
		if (c->root_subject
		    && (container = g_hash_table_lookup(subject_table, c->root_subject))
		    && (container != c)) {
			d(printf(" matching %p %s\n", container, container->root_subject));
			if (c->message == NULL && container->message == NULL) {
				d(printf("merge containers children\n"));
				/* steal the children from c onto container, and unlink c */
				scan = (CamelFolderThreadNode *)&container->child;
				while (scan->next)
					scan = scan->next;
				scan->next = c->child;
				clast->next = c->next;
				e_memchunk_free(thread->node_chunks, c);
				continue;
			} if (c->message == NULL && container->message != NULL) {
				d(printf("container is non-empty parent\n"));
				remove_node(cp, container, &clast);
				container_add_child(c, container);
			} else if (c->message != NULL && container->message == NULL) {
				d(printf("container is empty child\n"));
				clast->next = c->next;
				container_add_child(container, c);
				continue;
			} else if (c->re && !container->re) {
				d(printf("container is re\n"));
				clast->next = c->next;
				container_add_child(container, c);
				continue;
			} else if (!c->re && container->re) {
				d(printf("container is not re\n"));
				remove_node(cp, container, &clast);
				container_add_child(c, container);
			} else if (c->re && container->re) {
				d(printf("subjects are common %p and %p\n", c, container));

				/* build a phantom node */
				remove_node(cp, container, &clast);
				remove_node(cp, c, &clast);

				scan = e_memchunk_alloc0(thread->node_chunks);

				scan->root_subject = c->root_subject;
				scan->re = c->re && container->re;
				scan->next = c->next;
				clast->next = scan;
				container_add_child(scan, c);
				container_add_child(scan, container);
				clast = scan;
				g_hash_table_insert(subject_table, scan->root_subject, scan);
				continue;
			}
		}
		clast = c;
	}
	g_hash_table_destroy(subject_table);
}

struct _tree_info {
	GHashTable *visited;
};

static int
dump_tree_rec(struct _tree_info *info, CamelFolderThreadNode *c, int depth)
{
	char *p;
	int count=0;

	p = alloca(depth*2+1);
	memset(p, ' ', depth*2);
	p[depth*2] = 0;

	while (c) {
		if (g_hash_table_lookup(info->visited, c)) {
			printf("WARNING: NODE REVISITED: %p\n", c);
		} else {
			g_hash_table_insert(info->visited, c, c);
		}
		if (c->message) {
			printf("%s %p Subject: %s <%.8s>\n", p, c, camel_message_info_subject(c->message), c->message->message_id.id.hash);
			count += 1;
		} else {
			printf("%s %p <empty>\n", p, c);
		}
		if (c->child)
			count += dump_tree_rec(info, c->child, depth+1);
		c = c->next;
	}
	return count;
}

int
camel_folder_threaded_messages_dump(CamelFolderThreadNode *c)
{
	int count;
	struct _tree_info info;

	info.visited = g_hash_table_new(g_direct_hash, g_direct_equal);
	count = dump_tree_rec(&info, c, 0);
	g_hash_table_destroy(info.visited);
	return count;
}

static int
sort_node(const void *a, const void *b)
{
	const CamelFolderThreadNode *a1 = ((CamelFolderThreadNode **)a)[0];
	const CamelFolderThreadNode *b1 = ((CamelFolderThreadNode **)b)[0];

	/* if we have no message, it must be a dummy node, which 
	   also means it must have a child, just use that as the
	   sort data (close enough?) */
	if (a1->message == NULL)
		a1 = a1->child;
	if (b1->message == NULL)
		b1 = b1->child;
	if (a1->order == b1->order)
		return 0;
	if (a1->order < b1->order)
		return -1;
	else
		return 1;
}

static void
sort_thread(CamelFolderThreadNode **cp)
{
	CamelFolderThreadNode *c, *head, **carray;
	int size=0;

	c = *cp;
	while (c) {
		/* sort the children while we're at it */
		if (c->child)
			sort_thread(&c->child);
		size++;
		c = c->next;
	}
	if (size<2)
		return;
	carray = alloca(size*sizeof(CamelFolderThreadNode *));
	c = *cp;
	size=0;
	while (c) {
		carray[size] = c;
		c = c->next;
		size++;
	}
	qsort(carray, size, sizeof(CamelFolderThreadNode *), sort_node);
	size--;
	head = carray[size];
	head->next = NULL;
	size--;
	do {
		c = carray[size];
		c->next = head;
		head = c;
		size--;
	} while (size>=0);
	*cp = head;
}

static guint id_hash(void *key)
{
	CamelSummaryMessageID *id = (CamelSummaryMessageID *)key;

	return id->id.part.lo;
}

static gint id_equal(void *a, void *b)
{
	return ((CamelSummaryMessageID *)a)->id.id == ((CamelSummaryMessageID *)b)->id.id;
}

/**
 * camel_folder_thread_messages_new:
 * @folder: 
 * @uids: The subset of uid's to thread.  If NULL. then thread all
 * uid's in @folder.
 * 
 * Thread a (subset) of the messages in a folder.  And sort the result
 * in summary order.
 * 
 * Return value: A CamelFolderThread contianing a tree of CamelFolderThreadNode's
 * which represent the threaded structure of the messages.
 **/
CamelFolderThread *
camel_folder_thread_messages_new(CamelFolder *folder, GPtrArray *uids)
{
	GHashTable *id_table, *no_id_table;
	int i;
	CamelFolderThreadNode *c, *child, *head;
	CamelFolderThread *thread;
	GHashTable *wanted = NULL;
	GPtrArray *summary;

#ifdef TIMEIT
	struct timeval start, end;
	unsigned long diff;

	gettimeofday(&start, NULL);
#endif

	thread = g_malloc(sizeof(*thread));
	thread->tree = NULL;
	thread->node_chunks = e_memchunk_new(32, sizeof(CamelFolderThreadNode));
	thread->folder = folder;
	camel_object_ref((CamelObject *)folder);

	/* wanted is the list of what we want, we put it in a hash for quick lookup */
	if (uids) {
		wanted = g_hash_table_new(g_str_hash, g_str_equal);
		for (i=0;i<uids->len;i++)
			g_hash_table_insert(wanted, uids->pdata[i], uids->pdata[i]);
	}

	thread->summary = summary = camel_folder_get_summary(folder);
	
	id_table = g_hash_table_new((GHashFunc)id_hash, (GCompareFunc)id_equal);
	no_id_table = g_hash_table_new(NULL, NULL);
	for (i=0;i<summary->len;i++) {
		CamelMessageInfo *mi = summary->pdata[i];
		const char *uid = camel_message_info_uid(mi);

		if (wanted && g_hash_table_lookup(wanted, uid) == 0)
			continue;

		if (mi->message_id.id.id) {
			c = g_hash_table_lookup(id_table, &mi->message_id);
			/* check for duplicate messages */
			if (c) {
				/* if duplicate, just make out it is a no-id message,  but try and insert it
				   into the right spot in the tree */
				d(printf("doing: (duplicate message id)\n"));
				c = e_memchunk_alloc0(thread->node_chunks);
				g_hash_table_insert(no_id_table, (void *)mi, c);
			} else {
				d(printf("doing : %.8s\n", mi->message_id.id.hash));
				c = e_memchunk_alloc0(thread->node_chunks);
				g_hash_table_insert(id_table, (void *)&mi->message_id, c);
			}
		} else {
			d(printf("doing : (no message id)\n"));
			c = e_memchunk_alloc0(thread->node_chunks);
			g_hash_table_insert(no_id_table, (void *)mi, c);
		}

		c->message = mi;
		c->order = i;
		child = c;
		if (mi->references) {
			int j;

			d(printf("references:\n"));
			for (j=0;j<mi->references->size;j++) {
				/* should never be empty, but just incase */
				if (mi->references->references[j].id.id == 0)
					continue;

				c = g_hash_table_lookup(id_table, &mi->references->references[j]);
				if (c == NULL) {
					d(printf("not found\n"));
					c = e_memchunk_alloc0(thread->node_chunks);
					g_hash_table_insert(id_table, &mi->references->references[j], c);
				}
				if (c!=child)
					container_parent_child(c, child);
				child = c;
			}
		}
	}

	d(printf("\n\n"));
	/* build a list of root messages (no parent) */
	head = NULL;
	g_hash_table_foreach(id_table, hashloop, &head);
	g_hash_table_foreach(no_id_table, hashloop, &head);

	g_hash_table_destroy(id_table);
	g_hash_table_destroy(no_id_table);

	/* remove empty parent nodes */
	prune_empty(thread, &head);

	/* find any siblings which missed out */
	group_root_set(thread, &head);

#if 0
	printf("finished\n");
	i = camel_folder_thread_messages_dump(head);
	printf("%d count, %d items in tree\n", uids->len, i);
#endif

	sort_thread(&head);

	/* remove any phantom nodes, this could possibly be put in group_root_set()? */
	c = &head;
	while (c->next) {
		CamelFolderThreadNode *scan, *newtop;

		child = c->next;
		if (child->message == NULL) {
			newtop = child->child;
			/* unlink pseudo node */
			c->next = newtop;

			/* link its siblings onto the end of its children */
			scan = &newtop->child;
			while (scan->next)
				scan = scan->next;
			scan->next = newtop->next;
			/* and link the now 'real' node into the list */
			newtop->next = child->next;
			c = newtop->next;
			e_memchunk_free(thread->node_chunks, child);
		} else {
			c = child;
		}
	}


	thread->tree = head;

#ifdef TIMEIT
	gettimeofday(&end, NULL);
	diff = end.tv_sec * 1000 + end.tv_usec/1000;
	diff -= start.tv_sec * 1000 + start.tv_usec/1000;
	printf("Message threading %d messages took %ld.%03ld seconds\n",
	       uids->len, diff / 1000, diff % 1000);
#endif

	return thread;
}

/**
 * camel_folder_thread_messages_destroy:
 * @thread: 
 * 
 * Free all memory associated with the thread descriptor @thread.
 **/
void
camel_folder_thread_messages_destroy(CamelFolderThread *thread)
{
	camel_folder_free_summary(thread->folder, thread->summary);
	camel_object_unref((CamelObject *)thread->folder);
	e_memchunk_destroy(thread->node_chunks);
	g_free(thread);
}

#if 0
/* intended for incremental update.  Not implemented yet as, well, its probbaly
   not worth it (memory overhead vs speed, may as well just rethread the whole
   lot?)

   But it might be implemented at a later date.
*/
void
camel_folder_thread_messages_add(CamelFolderThread *thread, CamelFolder *folder, GPtrArray *uids)
{
	
}

void
thread_messages_remove(CamelFolderThread *thread, CamelFolder *folder, GPtrArray *uids)
{
	
}
#endif