// Copyright (c) Athena Dev Teams - Licensed under GNU GPL
// For more information, see LICENCE in the main folder

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "../common/cbasetypes.h"
#include "../common/nullpo.h"
#include "../common/showmsg.h"
#include "../common/malloc.h"
#include "map.h"
#include "battle.h"

#ifdef MEMWATCH
#include "memwatch.h"
#endif

//#define PATH_STANDALONETEST

#define MAX_HEAP 150

struct tmp_path { short x,y,dist,before,cost,flag;};
#define calc_index(x,y) (((x)+(y)*MAX_WALKPATH) & (MAX_WALKPATH*MAX_WALKPATH-1))

const char walk_choices [3][3] =
{
	{1,0,7},
	{2,-1,6},
	{3,4,5},
};

/*==========================================
 * 経路探索補助heap push
 *------------------------------------------*/
static void push_heap_path(int *heap,struct tmp_path *tp,int index)
{
	int i,h;

	heap[0]++;

	for(h=heap[0]-1,i=(h-1)/2;
		h>0 && tp[index].cost<tp[heap[i+1]].cost;
		i=(h-1)/2)
		heap[h+1]=heap[i+1],h=i;
	heap[h+1]=index;
}

/*==========================================
 * 経路探索補助heap update
 * costが減ったので根の方へ移動
 *------------------------------------------*/
static void update_heap_path(int *heap,struct tmp_path *tp,int index)
{
	int i,h;

	for(h=0;h<heap[0];h++)
		if(heap[h+1]==index)
			break;
	if(h==heap[0]){
		ShowError("update_heap_path bug\n");
		exit(1);
	}
	for(i=(h-1)/2;
		h>0 && tp[index].cost<tp[heap[i+1]].cost;
		i=(h-1)/2)
		heap[h+1]=heap[i+1],h=i;
	heap[h+1]=index;
}

/*==========================================
 * 経路探索補助heap pop
 *------------------------------------------*/
static int pop_heap_path(int *heap,struct tmp_path *tp)
{
	int i,h,k;
	int ret,last;

	if(heap[0]<=0)
		return -1;
	ret=heap[1];
	last=heap[heap[0]];
	heap[0]--;

	for(h=0,k=2;k<heap[0];k=k*2+2){
		if(tp[heap[k+1]].cost>tp[heap[k]].cost)
			k--;
		heap[h+1]=heap[k+1], h=k;
	}
	if(k==heap[0])
		heap[h+1]=heap[k], h=k-1;

	for(i=(h-1)/2;
		h>0 && tp[heap[i+1]].cost>tp[last].cost;
		i=(h-1)/2)
		heap[h+1]=heap[i+1],h=i;
	heap[h+1]=last;

	return ret;
}

/*==========================================
 * 現在の点のcost計算
 *------------------------------------------*/
static int calc_cost(struct tmp_path *p,int x1,int y1)
{
	int xd,yd;

	xd=x1-p->x;
	if(xd<0) xd=-xd;
	yd=y1-p->y;
	if(yd<0) yd=-yd;
	return (xd+yd)*10+p->dist;
}

/*==========================================
 * 必要ならpathを追加/修正する
 *------------------------------------------*/
static int add_path(int *heap,struct tmp_path *tp,int x,int y,int dist,int before,int cost)
{
	int i;

	i=calc_index(x,y);

	if(tp[i].x==x && tp[i].y==y){
		if(tp[i].dist>dist){
			tp[i].dist=dist;
			tp[i].before=before;
			tp[i].cost=cost;
			if(tp[i].flag)
				push_heap_path(heap,tp,i);
			else
				update_heap_path(heap,tp,i);
			tp[i].flag=0;
		}
		return 0;
	}

	if(tp[i].x || tp[i].y)
		return 1;

	tp[i].x=x;
	tp[i].y=y;
	tp[i].dist=dist;
	tp[i].before=before;
	tp[i].cost=cost;
	tp[i].flag=0;
	push_heap_path(heap,tp,i);

	return 0;
}


/*==========================================
 * (x,y)が移動不可能地帯かどうか
 * flag 0x10000 遠距離攻撃判定
 *------------------------------------------*/
static int can_place(struct map_data *m,int x,int y,int flag)
{
	if(map_getcellp(m,x,y,CELL_CHKPASS))
		return 1;
	if((flag&0x10000)&&map_getcellp(m,x,y,CELL_CHKGROUND))
		return 1;
#ifdef CELL_NOSTACK
	//Special flag for CELL_NOSTACK systems. Returns true when the given cell is stacked. [Skotlex]
	if((flag&0x30000)&&map_getcellp(m,x,y,CELL_CHKSTACK))
		return 1;
#endif
	return 0;
}

/*==========================================
 * (x0,y0)から(x1,y1)へ1歩で移動可能か計算
 *------------------------------------------*/
static int can_move(struct map_data *m,int x0,int y0,int x1,int y1,int flag)
{
	if(x1<0 || y1<0 || x1>=m->xs || y1>=m->ys)
		return 0;
	if(flag&0x20000) //Flag to ignore everything, for use with Taekwon's Jump skill currently. [Skotlex] 
		return 1;
#ifndef CELL_NOSTACK
	//In no-stack mode, do not check current cell.
	if(!can_place(m,x0,y0,flag))
		return 0;
#endif
	if(!can_place(m,x1,y1,flag))
		return 0;
	if(x0==x1 || y0==y1)
		return 1;
	if(!can_place(m,x0,y1,flag) || !can_place(m,x1,y0,flag))
		return 0;
	return 1;
}

/*==========================================
 * (x0,y0)から(dx,dy)方向へcountセル分
 * 吹き飛ばしたあとの座標を所得
 *------------------------------------------*/
int path_blownpos(int m,int x0,int y0,int dx,int dy,int count)
{
	struct map_data *md;

	if(!map[m].gat)
		return -1;
	md=&map[m];

	if(count>25){ //Cap to prevent too much processing...?
		if(battle_config.error_log)
			ShowWarning("path_blownpos: count too many %d !\n",count);
		count=25;
	}
	if(dx>1 || dx<-1 || dy>1 || dy<-1){
		if(battle_config.error_log)
			ShowError("path_blownpos: illeagal dx=%d or dy=%d !\n",dx,dy);
		dx=(dx>=0)?1:((dx<0)?-1:0);
		dy=(dy>=0)?1:((dy<0)?-1:0);
	}
	
	while( (count--)>0 && (dx || dy) ){
		if( !can_move(md,x0,y0,x0+dx,y0+dy,0) ){
			int fx=(dx!=0 && can_move(md,x0,y0,x0+dx,y0,0));
			int fy=(dy!=0 && can_move(md,x0,y0,x0,y0+dy,0));
			if( fx && fy ){
				if(rand()&1) dx=0;
				else		 dy=0;
			}
			if( !fx )		dx=0;
			if( !fy )		dy=0;
		}
		x0+=dx;
		y0+=dy;
	}
	return (x0<<16)|y0;
}

/*==========================================
 *  遠距離攻撃が可能かどうかを返す
 *------------------------------------------*/
int path_search_long_real(struct shootpath_data *spd,int m,int x0,int y0,int x1,int y1,cell_t flag)
{
	int dx, dy;
	int wx = 0, wy = 0;
	int weight;
	struct map_data *md;

	if (!map[m].gat)
		return 0;
	md = &map[m];

	dx = (x1 - x0);
	if (dx < 0) {
		swap(x0, x1);
		swap(y0, y1);
		dx = -dx;
	}
	dy = (y1 - y0);

	if (spd) {
		spd->rx = spd->ry = 0;
		spd->len = 1;
		spd->x[0] = x0;
		spd->y[0] = y0;
	}

	if (map_getcellp(md,x1,y1,flag))
		return 0;

	if (dx > abs(dy)) {
		weight = dx;
		if (spd)
			spd->ry=1;
	} else {
		weight = abs(y1 - y0);
		if (spd)
			spd->rx=1;
	}

	while (x0 != x1 || y0 != y1) {
		if (map_getcellp(md,x0,y0,flag))
			return 0;
		wx += dx;
		wy += dy;
		if (wx >= weight) {
			wx -= weight;
			x0 ++;
		}
		if (wy >= weight) {
			wy -= weight;
			y0 ++;
		} else if (wy < 0) {
			wy += weight;
			y0 --;
		}
		if (spd && spd->len<MAX_WALKPATH) {
			spd->x[spd->len] = x0;
			spd->y[spd->len] = y0;
			spd->len++;
		}
	}

	return 1;
}

/*==========================================
 * path探索 (x0,y0)->(x1,y1)
 *------------------------------------------*/
int path_search_real(struct walkpath_data *wpd,int m,int x0,int y0,int x1,int y1,int flag,cell_t flag2)
{
	int heap[MAX_HEAP+1];
	struct tmp_path tp[MAX_WALKPATH*MAX_WALKPATH];
	register int i,x,y,dx,dy;
	int rp,xs,ys;
	struct map_data *md;

	nullpo_retr(0, wpd);

	if(!map[m].gat)
		return -1;
	md=&map[m];
#ifdef CELL_NOSTACK
	//Do not check starting cell as that would get you stuck.
	if(x0<0 || x0>=md->xs || y0<0 || y0>=md->ys)
#else
	if(x0<0 || x0>=md->xs || y0<0 || y0>=md->ys || map_getcellp(md,x0,y0,flag2))
#endif
		return -1;
	if(x1<0 || x1>=md->xs || y1<0 || y1>=md->ys || map_getcellp(md,x1,y1,flag2))
		return -1;

	// easy and better [Meruru]
	dx = ((dx = x1-x0)) ? ((dx<0) ? -1 : 1) : 0;
	dy = ((dy = y1-y0)) ? ((dy<0) ? -1 : 1) : 0;

	//Better faster stronger simple path algo. [Meruru]
	for(x=x0,y=y0,i=0;i < sizeof(wpd->path);)
	{
		wpd->path[i++] = walk_choices[-dy + 1][dx + 1];

		x += dx;
		y += dy;

		if(x == x1) dx = 0;
		if(y == y1) dy = 0;

		if((!dx && !dy) || map_getcellp(md,x,y,flag2))
			break;
	}

	/*
	You may be thinking what about diagonal
	moves? Can't they cause a error with this somehow?
	Answer is NO! The only time this can cause a error
	is if the target block lies on the diagonal and
	is non walkable. But rember we already checked that
	up above! So no problems here... I think [Meruru]
	*/

	if (x==x1 && y==y1)
	{ //easy path successful.
		wpd->path_len=i;
		wpd->path_pos=0;
		wpd->path_half=0;
		return 0;
	}
	
	if(flag&1)
		return -1;

	memset(tp,0,sizeof(tp));

	i=calc_index(x0,y0);
	tp[i].x=x0;
	tp[i].y=y0;
	tp[i].dist=0;
	tp[i].before=0;
	tp[i].cost=calc_cost(&tp[i],x1,y1);
	tp[i].flag=0;
	heap[0]=0;
	push_heap_path(heap,tp,calc_index(x0,y0));
	xs = md->xs-1; // あらかじめ１減算しておく
	ys = md->ys-1;
	while(1){
		int e=0,f=0,dist,cost,dc[4];

		if(heap[0]==0)
			return -1;
		rp   = pop_heap_path(heap,tp);
		x    = tp[rp].x;
		y    = tp[rp].y;
		dist = tp[rp].dist + 10;
		cost = tp[rp].cost;
		if(x==x1 && y==y1) break;

		// dc[0] : y++ の時のコスト増分
		// dc[1] : x-- の時のコスト増分
		// dc[2] : y-- の時のコスト増分
		// dc[3] : x++ の時のコスト増分

		if(y < ys && !map_getcellp(md,x  ,y+1,flag2)) {
			f |= 1; dc[0] = (y >= y1 ? 20 : 0);
			e+=add_path(heap,tp,x  ,y+1,dist,rp,cost+dc[0]); // (x,   y+1)
		}
		if(x > 0  && !map_getcellp(md,x-1,y  ,flag2)) {
			f |= 2; dc[1] = (x <= x1 ? 20 : 0);
			e+=add_path(heap,tp,x-1,y  ,dist,rp,cost+dc[1]); // (x-1, y  )
		}
		if(y > 0  && !map_getcellp(md,x  ,y-1,flag2)) {
			f |= 4; dc[2] = (y <= y1 ? 20 : 0);
			e+=add_path(heap,tp,x  ,y-1,dist,rp,cost+dc[2]); // (x  , y-1)
		}
		if(x < xs && !map_getcellp(md,x+1,y  ,flag2)) {
			f |= 8; dc[3] = (x >= x1 ? 20 : 0);
			e+=add_path(heap,tp,x+1,y  ,dist,rp,cost+dc[3]); // (x+1, y  )
		}
		if( (f & (2+1)) == (2+1) && !map_getcellp(md,x-1,y+1,flag2))
			e+=add_path(heap,tp,x-1,y+1,dist+4,rp,cost+dc[1]+dc[0]-6);		// (x-1, y+1)
		if( (f & (2+4)) == (2+4) && !map_getcellp(md,x-1,y-1,flag2))
			e+=add_path(heap,tp,x-1,y-1,dist+4,rp,cost+dc[1]+dc[2]-6);		// (x-1, y-1)
		if( (f & (8+4)) == (8+4) && !map_getcellp(md,x+1,y-1,flag2))
			e+=add_path(heap,tp,x+1,y-1,dist+4,rp,cost+dc[3]+dc[2]-6);		// (x+1, y-1)
		if( (f & (8+1)) == (8+1) && !map_getcellp(md,x+1,y+1,flag2))
			e+=add_path(heap,tp,x+1,y+1,dist+4,rp,cost+dc[3]+dc[0]-6);		// (x+1, y+1)
		tp[rp].flag=1;
		if(e || heap[0]>=MAX_HEAP-5)
			return -1;
	}
	if(x==x1 && y==y1) {
		int len,j;

		for(len=0,i=rp;len<100 && i!=calc_index(x0,y0);i=tp[i].before,len++);
		if(len==100 || len>=sizeof(wpd->path))
			return -1;
		wpd->path_len=len;
		wpd->path_pos=0;
		wpd->path_half=0;
		for(i=rp,j=len-1;j>=0;i=tp[i].before,j--) {
			int dx  = tp[i].x - tp[tp[i].before].x;
			int dy  = tp[i].y - tp[tp[i].before].y;
			int dir;
			if( dx == 0 ) {
				dir = (dy > 0 ? 0 : 4);
			} else if( dx > 0 ) {
				dir = (dy == 0 ? 6 : (dy < 0 ? 5 : 7) );
			} else {
				dir = (dy == 0 ? 2 : (dy > 0 ? 1 : 3) );
			}
			wpd->path[j] = dir;
		}
#if 0
		// test
		{
			int dirx[8]={0,-1,-1,-1,0,1,1,1};
			int diry[8]={1,1,0,-1,-1,-1,0,1};
			x = x0; y = y0;
			for(i = 0; i < wpd->path_len; i++) {
				x += dirx[ wpd->path[i] ];
				y += diry[ wpd->path[i] ];
				if( map_getcellp(md,x,y,flag2) ) {
					printf("path_search_real: cannot move(%d, %d)\n", x, y);
					return -1;
				}
			}
			if( x != x1 || y != y1 ) {
				printf("path_search_real: dest position is wrong. ok:(%d, %d) ng:(%d,%d)\n", x1, y1, x, y);
				return -1;
			}
		}
#endif
		return 0;
	}
	return -1;
}

/*==========================================
 * path探索 (x0,y0)->(x1,y1)
 *------------------------------------------*/

#ifdef PATH_STANDALONETEST
char gat[64][64]={
	{0,0,0,0,0,0,0,0,0,0},
	{0,0,0,0,0,0,0,0,0,0},
	{0,0,0,0,0,0,0,0,0,0},
	{0,0,0,0,0,0,0,0,0,0},
	{0,0,0,0,1,0,0,0,0,0},
};
struct map_data map[1];

/*==========================================
 * 経路探索ルーチン単体テスト用main関数
 *------------------------------------------*/
void main(int argc,char *argv[])
{
	struct walkpath_data wpd;

	map[0].gat=gat;
	map[0].xs=64;
	map[0].ys=64;

	path_search(&wpd,0,3,4,5,4);
	path_search(&wpd,0,5,4,3,4);
	path_search(&wpd,0,6,4,3,4);
	path_search(&wpd,0,7,4,3,4);
	path_search(&wpd,0,4,3,4,5);
	path_search(&wpd,0,4,2,4,5);
	path_search(&wpd,0,4,1,4,5);
	path_search(&wpd,0,4,5,4,3);
	path_search(&wpd,0,4,6,4,3);
	path_search(&wpd,0,4,7,4,3);
	path_search(&wpd,0,7,4,3,4);
	path_search(&wpd,0,8,4,3,4);
	path_search(&wpd,0,9,4,3,4);
	path_search(&wpd,0,10,4,3,4);
	path_search(&wpd,0,11,4,3,4);
	path_search(&wpd,0,12,4,3,4);
	path_search(&wpd,0,13,4,3,4);
	path_search(&wpd,0,14,4,3,4);
	path_search(&wpd,0,15,4,3,4);
	path_search(&wpd,0,16,4,3,4);
	path_search(&wpd,0,17,4,3,4);
	path_search(&wpd,0,18,4,3,4);
}
#endif