#include "glib_slice.h"
#ifdef DEBUG_CACHE
#include <stdio.h>
#endif
#include <string.h>
#include "debug.h"
#include "cache.h"

struct cache_entry {
	int usage;
	int size;
	struct cache_entry_list *where;
	struct cache_entry *next;
	struct cache_entry *prev;
	int id[0];
};

struct cache_entry_list {
	struct cache_entry *first, *last;
	int size;
};

struct cache {
	struct cache_entry_list t1,b1,t2,b2,*insert;
	int size,id_size,entry_size;
	int t1_target;
	int misses;
	int hits;
	GHashTable *hash;
};

static void
cache_entry_dump(struct cache *cache, struct cache_entry *entry)
{
	int i,size;
	dbg(0,"Usage: %d size %d\n",entry->usage, entry->size);
	if (cache)
		size=cache->id_size;
	else
		size=5;
	for (i = 0 ; i < size ; i++) {
		dbg(0,"0x%x\n", entry->id[i]);
	}
}

static void
cache_list_dump(char *str, struct cache *cache, struct cache_entry_list *list)
{
	struct cache_entry *first=list->first;
	dbg(0,"dump %s %d\n",str, list->size);
	while (first) {
		cache_entry_dump(cache, first);
		first=first->next;
	}
}

static guint
cache_hash4(gconstpointer key)
{
	int *id=(int *)key;
	return id[0];
}

static guint
cache_hash20(gconstpointer key)
{
	int *id=(int *)key;
	return id[0]^id[1]^id[2]^id[3]^id[4];
}

static gboolean
cache_equal4(gconstpointer a, gconstpointer b)
{
	int *ida=(int *)a;
	int *idb=(int *)b;

	return ida[0] == idb[0];
}

static gboolean
cache_equal20(gconstpointer a, gconstpointer b)
{
	int *ida=(int *)a;
	int *idb=(int *)b;

	return(ida[0] == idb[0] &&
	       ida[1] == idb[1] &&
	       ida[2] == idb[2] &&
	       ida[3] == idb[3] &&
	       ida[4] == idb[4]);
}

struct cache *
cache_new(int id_size, int size)
{
	struct cache *cache=g_new0(struct cache, 1);
	
	cache->id_size=id_size/4;
	cache->entry_size=cache->id_size*sizeof(int)+sizeof(struct cache_entry);
	cache->size=size;
	switch (id_size) {
	case 4:
		cache->hash=g_hash_table_new(cache_hash4, cache_equal4);
		break;
	case 20:
		cache->hash=g_hash_table_new(cache_hash20, cache_equal20);
		break;
	default:
		dbg(0,"cache with id_size of %d not supported\n", id_size);
		g_free(cache);
		cache=NULL;
	}
	return cache;
}

static void
cache_insert_mru(struct cache *cache, struct cache_entry_list *list, struct cache_entry *entry)
{
	entry->prev=NULL;
	entry->next=list->first;
	entry->where=list;
	if (entry->next)
		entry->next->prev=entry;
	list->first=entry;
	if (! list->last)
		list->last=entry;
	list->size+=entry->size;
	if (cache) 
		g_hash_table_insert(cache->hash, (gpointer)entry->id, entry);
}

static void
cache_remove_from_list(struct cache_entry_list *list, struct cache_entry *entry)
{
	if (entry->prev) 
		entry->prev->next=entry->next;
	else
		list->first=entry->next;
	if (entry->next)
		entry->next->prev=entry->prev;
	else
		list->last=entry->prev;
	list->size-=entry->size;
}

static void
cache_remove(struct cache *cache, struct cache_entry *entry)
{
	dbg(1,"remove 0x%x 0x%x 0x%x 0x%x 0x%x\n", entry->id[0], entry->id[1], entry->id[2], entry->id[3], entry->id[4]);
	g_hash_table_remove(cache->hash, (gpointer)(entry->id));
	g_slice_free1(entry->size, entry);
}

static struct cache_entry *
cache_remove_lru_helper(struct cache_entry_list *list)
{
	struct cache_entry *last=list->last;
	if (! last)
		return NULL;
	list->last=last->prev;
	if (last->prev)
		last->prev->next=NULL;
	else
		list->first=NULL;
	list->size-=last->size;
	return last;
}

static struct cache_entry *
cache_remove_lru(struct cache *cache, struct cache_entry_list *list)
{
	struct cache_entry *last;
	int seen=0;
	while (list->last && list->last->usage && seen < list->size) {
		last=cache_remove_lru_helper(list);
		cache_insert_mru(NULL, list, last);
		seen+=last->size;
	}
	last=list->last;
	if (! last || last->usage || seen >= list->size) 
		return NULL;
	dbg(1,"removing %d\n", last->id[0]);
	cache_remove_lru_helper(list);
	if (cache) {
		cache_remove(cache, last);
		return NULL;
	}
	return last;
}

void *
cache_entry_new(struct cache *cache, void *id, int size)
{
	struct cache_entry *ret;
	size+=cache->entry_size;
	cache->misses+=size;
	ret=(struct cache_entry *)g_slice_alloc0(size);
	ret->size=size;
	ret->usage=1;
	memcpy(ret->id, id, cache->id_size*sizeof(int));
	return &ret->id[cache->id_size];
}

void
cache_entry_destroy(struct cache *cache, void *data)
{
	struct cache_entry *entry=(struct cache_entry *)((char *)data-cache->entry_size);
	dbg(1,"destroy 0x%x 0x%x 0x%x 0x%x 0x%x\n", entry->id[0], entry->id[1], entry->id[2], entry->id[3], entry->id[4]);
	entry->usage--;
}

static struct cache_entry *
cache_trim(struct cache *cache, struct cache_entry *entry)
{
	struct cache_entry *new_entry;
	dbg(1,"trim 0x%x 0x%x 0x%x 0x%x 0x%x\n", entry->id[0], entry->id[1], entry->id[2], entry->id[3], entry->id[4]);
	dbg(1,"Trim %x from %d -> %d\n", entry->id[0], entry->size, cache->size);
	if ( cache->entry_size < entry->size )
	{
	    g_hash_table_remove(cache->hash, (gpointer)(entry->id));

	    new_entry = g_slice_alloc0(cache->entry_size);
	    memcpy(new_entry, entry, cache->entry_size);
	    g_slice_free1( entry->size, entry);
	    new_entry->size = cache->entry_size;

	    g_hash_table_insert(cache->hash, (gpointer)new_entry->id, new_entry);
	}
	else
	{
	    new_entry = entry; 
	}
	
	return new_entry;
}

static struct cache_entry *
cache_move(struct cache *cache, struct cache_entry_list *old, struct cache_entry_list *new)
{
	struct cache_entry *entry;
	entry=cache_remove_lru(NULL, old);
	if (! entry)
		return NULL;
	entry=cache_trim(cache, entry);
	cache_insert_mru(NULL, new, entry);
	return entry;
}

static int
cache_replace(struct cache *cache)
{
	if (cache->t1.size >= MAX(1,cache->t1_target)) {
		dbg(1,"replace 12\n");
		if (!cache_move(cache, &cache->t1, &cache->b1))
			cache_move(cache, &cache->t2, &cache->b2);
	} else {
		dbg(1,"replace t2\n");
		if (!cache_move(cache, &cache->t2, &cache->b2))
			cache_move(cache, &cache->t1, &cache->b1);
	}
#if 0
	if (! entry) {
		cache_dump(cache);
		exit(0);
	}
#endif
	return 1;
}

void
cache_flush(struct cache *cache, void *id)
{
	struct cache_entry *entry=g_hash_table_lookup(cache->hash, id);
	if (entry) {
		cache_remove_from_list(entry->where, entry);
		cache_remove(cache, entry);
	}
}

void
cache_flush_data(struct cache *cache, void *data)
{
	struct cache_entry *entry=(struct cache_entry *)((char *)data-cache->entry_size);
	if (entry) {
		cache_remove_from_list(entry->where, entry);
		cache_remove(cache, entry);
	}
}


void *
cache_lookup(struct cache *cache, void *id) {
	struct cache_entry *entry;

	dbg(1,"get %d\n", ((int *)id)[0]);
	entry=g_hash_table_lookup(cache->hash, id);
	if (entry == NULL) {
		cache->insert=&cache->t1;
#ifdef DEBUG_CACHE
		fprintf(stderr,"-");
#endif
		dbg(1,"not in cache\n");
		return NULL;
	}
	dbg(1,"found 0x%x 0x%x 0x%x 0x%x 0x%x\n", entry->id[0], entry->id[1], entry->id[2], entry->id[3], entry->id[4]);
	if (entry->where == &cache->t1 || entry->where == &cache->t2) {
		cache->hits+=entry->size;
#ifdef DEBUG_CACHE
		if (entry->where == &cache->t1)
			fprintf(stderr,"h");
		else
			fprintf(stderr,"H");
#endif
		dbg(1,"in cache %s\n", entry->where == &cache->t1 ? "T1" : "T2");
		cache_remove_from_list(entry->where, entry);
		cache_insert_mru(NULL, &cache->t2, entry);
		entry->usage++;
		return &entry->id[cache->id_size];
	} else {
		if (entry->where == &cache->b1) {
#ifdef DEBUG_CACHE
			fprintf(stderr,"m");
#endif
			dbg(1,"in phantom cache B1\n");
			cache->t1_target=MIN(cache->t1_target+MAX(cache->b2.size/cache->b1.size, 1),cache->size);
			cache_remove_from_list(&cache->b1, entry);
		} else if (entry->where == &cache->b2) {
#ifdef DEBUG_CACHE
			fprintf(stderr,"M");
#endif
			dbg(1,"in phantom cache B2\n");
			cache->t1_target=MAX(cache->t1_target-MAX(cache->b1.size/cache->b2.size, 1),0);
			cache_remove_from_list(&cache->b2, entry);
		} else {
			dbg(0,"**ERROR** invalid where\n");
		}
		cache_replace(cache);
		cache_remove(cache, entry);
		cache->insert=&cache->t2;
		return NULL;
	}
}

void
cache_insert(struct cache *cache, void *data)
{
	struct cache_entry *entry=(struct cache_entry *)((char *)data-cache->entry_size);
	dbg(1,"insert 0x%x 0x%x 0x%x 0x%x 0x%x\n", entry->id[0], entry->id[1], entry->id[2], entry->id[3], entry->id[4]);
	if (cache->insert == &cache->t1) {
		if (cache->t1.size + cache->b1.size >= cache->size) {
			if (cache->t1.size < cache->size) {
				cache_remove_lru(cache, &cache->b1);
				cache_replace(cache);
			} else {
				cache_remove_lru(cache, &cache->t1);
			}
		} else {
			if (cache->t1.size + cache->t2.size + cache->b1.size + cache->b2.size >= cache->size) {
				if (cache->t1.size + cache->t2.size + cache->b1.size + cache->b2.size >= 2*cache->size) 
					cache_remove_lru(cache, &cache->b2);
				cache_replace(cache);
			}
		}
	}
	cache_insert_mru(cache, cache->insert, entry);
}

void *
cache_insert_new(struct cache *cache, void *id, int size)
{
	void *data=cache_entry_new(cache, id, size);
	cache_insert(cache, data);
	return data;	
}

static void
cache_stats(struct cache *cache)
{
	dbg(0,"hits %d misses %d hitratio %d size %d entry_size %d id_size %d T1 target %d\n", cache->hits, cache->misses, cache->hits*100/(cache->hits+cache->misses), cache->size, cache->entry_size, cache->id_size, cache->t1_target);
	dbg(0,"T1:%d B1:%d T2:%d B2:%d\n", cache->t1.size, cache->b1.size, cache->t2.size, cache->b2.size);
	cache->hits=0;
	cache->misses=0;
}

void
cache_dump(struct cache *cache)
{
	struct cache_entry *first;
	first=cache->t1.first;
	cache_stats(cache);
	cache_list_dump("T1", cache, &cache->t1);
	cache_list_dump("B1", cache, &cache->b1);
	cache_list_dump("T2", cache, &cache->t2);
	cache_list_dump("B2", cache, &cache->b2);
	dbg(0,"dump end\n");
}