//
// Copyright (c) 2001-2016, Andrew Aksyonoff
// Copyright (c) 2008-2016, Sphinx Technologies Inc
// All rights reserved
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License. You should have
// received a copy of the GPL license along with this program; if you
// did not, you can find it at http://www.gnu.org/
//

// for UNALIGNED_RAM_ACCESS
#include "config.h"

#if defined(_MSC_VER) && !defined(__cplusplus)
#define inline
#endif

// #define SNOWBALL2011

static unsigned char stem_en_doubles[] = "bdfgmnprt";

static unsigned char vowel_map[] =
	"\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\0\0\0\0\0\0\0\0\0\0\0" // 2
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" // 3
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" // 4
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" // 5
	//` a b c d e f g h i j k l m n o - NOLINT
	"\0\1\0\0\0\1\0\0\0\1\0\0\0\0\0\1" // 6
	//p q r s t u v w x y z - NOLINT
	"\0\0\0\0\0\1\0\0\0\1\0\0\0\0\0\0" // 7
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" // 8
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" // 9
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" // a
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" // b
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" // c
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" // d
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" // e
	"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"; // f

#undef is_vowel
#define is_vowel(idx) vowel_map[word[idx]]

static inline int stem_en_id ( unsigned char l )
{
	unsigned char * v = stem_en_doubles;
	while ( *v && *v!=l ) v++;
	return ( *v==l ) ? 1 : 0;
}

static inline int stem_en_ivwxy ( unsigned char l )
{
	return vowel_map[l] || l=='w' || l=='x' || l=='Y';
}

void stem_en_init ()
{
}

#define EXCBASE(b) ( iword==( ( (int)b[3]<<24 ) + ( (int)b[2]<<16 ) + ( (int)b[1]<<8 ) + (int)b[0] ) )
#define EXC4(a,b) ( len==4 && EXCBASE(b) )
#define EXC5(a,b) ( len==5 && EXCBASE(b) )
#define EXC6(a,b) ( len==6 && EXCBASE(b) && a[4]==b[4] )
#define EXC7(a,b) ( len==7 && EXCBASE(b) && a[4]==b[4] && a[5]==b[5] )
#define EXC8(a,b) ( len==8 && EXCBASE(b) && a[4]==b[4] && a[5]==b[5] && a[6]==b[6] )

void stem_en ( unsigned char * word, int len )
{
	int i, first_vowel, r1, r2, iword;
	unsigned char has_Y = 0;

	if ( len<=2 )
		return;

#if UNALIGNED_RAM_ACCESS
	iword = *(int*)word;
#else
	iword = ( (int)word[3]<<24 ) + ( (int)word[2]<<16 ) + ( (int)word[1]<<8 ) + (int)word[0];
#endif

	// check for 3-letter exceptions (currently just one, "sky") and shortcuts
	if ( len==3 )
	{
#define CHECK3(c1,c2,c3) if ( iword==( (c1<<0)+(c2<<8)+(c3<<16) ) ) return;
#ifdef SNOWBALL2011
#define CHECK3A CHECK3
#else
#define CHECK3A(c1,c2,c3) if ( iword==( (c1<<0)+(c2<<8)+(c3<<16) ) ) { word[2] = '\0'; return; }
#endif
		CHECK3 ( 't', 'h', 'e' );
		CHECK3 ( 'a', 'n', 'd' );
		CHECK3 ( 'y', 'o', 'u' );
		CHECK3A ( 'w', 'a', 's' );
		CHECK3A ( 'h', 'i', 's' );
		CHECK3 ( 'f', 'o', 'r' );
		CHECK3 ( 'h', 'e', 'r' );
		CHECK3 ( 's', 'h', 'e' );
		CHECK3 ( 'b', 'u', 't' );
		CHECK3 ( 'h', 'a', 'd' );
		CHECK3 ( 's', 'k', 'y' );
	}

	// check for 4..8-letter exceptions
	if ( len>=4 && len<=8 )
	{
		// check for 4-letter exceptions and shortcuts
		if ( len==4 )
		{
			// shortcuts
			if ( iword==0x74616874 ) return; // that
			if ( iword==0x68746977 ) return; // with
			if ( iword==0x64696173 ) return; // said
			if ( iword==0x6d6f7266 ) return; // from

			// exceptions
			if ( iword==0x7377656e ) return; // news
			if ( iword==0x65776f68 ) return; // howe
		}

		// all those exceptions only have a few valid endings; early check
		switch ( word[len-1] )
		{
			case 'd':
				if ( EXC7 ( word, "proceed" ) )		return;
				if ( EXC6 ( word, "exceed" ) )		return;
				if ( EXC7 ( word, "succeed" ) )		return;
				break;

			case 'g':
				if ( EXC5 ( word, "dying" ) )		{ word[1] = 'i'; word[2] = 'e'; word[3] = '\0'; return; }
				if ( EXC5 ( word, "lying" ) )		{ word[1] = 'i'; word[2] = 'e'; word[3] = '\0'; return; }
				if ( EXC5 ( word, "tying" ) )		{ word[1] = 'i'; word[2] = 'e'; word[3] = '\0'; return; }
				if ( EXC6 ( word, "inning" ) )		return;
				if ( EXC6 ( word, "outing" ) )		return;
				if ( EXC7 ( word, "canning" ) )		return;
#ifdef SNOWBALL2011
				if ( EXC7 ( word, "herring" ) )		return;
				if ( EXC7 ( word, "earring" ) )		return;
#endif
				break;

			case 's':
				if ( EXC5 ( word, "skies" ) )		{ word[2] = 'y'; word[3] = '\0'; return; }
				if ( EXC7 ( word, "innings" ) )		{ word[6] = '\0'; return; }
				if ( EXC7 ( word, "outings" ) )		{ word[6] = '\0';return; }
				if ( EXC8 ( word, "cannings" ) )	{ word[7] = '\0';return; }
#ifdef SNOWBALL2011
				if ( EXC4 ( word, "skis" ) )		{ word[3] = '\0'; return; }
				if ( EXC5 ( word, "atlas" ) )		return;
				if ( EXC6 ( word, "cosmos" ) )		return;
				if ( EXC4 ( word, "bias" ) )		return;
				if ( EXC5 ( word, "andes" ) )		return;
				if ( EXC8 ( word, "herrings" ) )	{ word[7] = '\0'; return; }
				if ( EXC8 ( word, "earrings" ) )	{ word[7] = '\0'; return; }
				if ( EXC8 ( word, "proceeds" ) )	{ word[7] = '\0'; return; }
				if ( EXC7 ( word, "exceeds" ) )		{ word[6] = '\0'; return; }
				if ( EXC8 ( word, "succeeds" ) )	{ word[7] = '\0'; return; }
#endif
				break;

			case 'y':
				if ( EXC4 ( word, "idly" ) )		{ word[3] = '\0';return; }
				if ( EXC6 ( word, "gently" ) )		{ word[5] = '\0';return; }
				if ( EXC4 ( word, "ugly" ) )		{ word[3] = 'i'; word[4] = '\0'; return; }
				if ( EXC5 ( word, "early" ) )		{ word[4] = 'i'; word[5] = '\0'; return; }
				if ( EXC4 ( word, "only" ) )		{ word[3] = 'i'; word[4] = '\0'; return; }
				if ( EXC6 ( word, "singly" ) )		{ word[5] = '\0'; return; }
				break;
		}
	}

	// hide consonant-style y's
	if ( word[0]=='y' )
		word[0] = has_Y = 'Y';
	for ( i=1; i<len; i++ )
		if ( word[i]=='y' && is_vowel ( i-1 ) )
			word[i] = has_Y = 'Y';

	// mark regions
	// R1 begins after first "vowel, consonant" sequence in the word
	// R2 begins after second "vowel, consonant" sequence
	if ( len>=5 && EXCBASE("gene") && word[4]=='r' )
	{
		r1 = 5; // gener-
		first_vowel = 1;
	}
#ifdef SNOWBALL2011
	else if ( len>=6 && EXCBASE("comm") && word[4]=='u' && word[5]=='n' )
	{
		r1 = 6; // commun-
		first_vowel = 1;
	} else if ( len>=5 && EXCBASE("arse") && word[4]=='n' )
	{
		r1 = 5; // arsen-
		first_vowel = 0;
	}
#endif
	else
	{
		for ( i=0; i<len && !is_vowel(i); i++ );
		first_vowel = i;

		for ( i=first_vowel; i<len-2; i++ )
			if ( is_vowel(i) && !is_vowel(i+1) )
				break;
		r1 = i+2;
	}
	for ( i=r1; i<len-2; i++ )
		if ( is_vowel(i) && !is_vowel(i+1) )
			break;
	r2 = i+2;

#undef W
#define W(p,c) ( word[len-p]==c )

#define SUFF2(c2,c1) ( len>=2 && W(1,c1) && W(2,c2) )
#define SUFF3(c3,c2,c1) ( len>=3 && W(1,c1) && W(2,c2) && W(3,c3) )
#define SUFF4(c4,c3,c2,c1) ( len>=4 && W(1,c1) && W(2,c2) && W(3,c3) && W(4,c4) )
#define SUFF5(c5,c4,c3,c2,c1) ( len>=5 && W(1,c1) && W(2,c2) && W(3,c3) && W(4,c4) && W(5,c5) )
#define SUFF6(c6,c5,c4,c3,c2,c1) ( len>=6 && W(1,c1) && W(2,c2) && W(3,c3) && W(4,c4) && W(5,c5) && W(6,c6) )
#define SUFF7(c7,c6,c5,c4,c3,c2,c1) ( len>=7 && W(1,c1) && W(2,c2) && W(3,c3) && W(4,c4) && W(5,c5) && W(6,c6) && W(7,c7) )

#define SUFF3A(c3,c2) ( len>=3 && W(2,c2) && W(3,c3) )
#define SUFF4A(c4,c3,c2) ( len>=4 && W(2,c2) && W(3,c3) && W(4,c4) )
#define SUFF5A(c5,c4,c3,c2) ( len>=5 && W(2,c2) && W(3,c3) && W(4,c4) && W(5,c5) )
#define SUFF6A(c6,c5,c4,c3,c2) ( len>=6 && W(2,c2) && W(3,c3) && W(4,c4) && W(5,c5) && W(6,c6) )
#define SUFF7A(c7,c6,c5,c4,c3,c2) ( len>=6 && W(2,c2) && W(3,c3) && W(4,c4) && W(5,c5) && W(6,c6) && W(7,c7) )

	///////////
	// STEP 1A
	///////////

#ifdef SNOWBALL2011
#define IED_ACTION { if ( len-->4 ) len--; }
#else
#define IED_ACTION { if ( len--!=4 ) len--; }
#endif

	switch ( word[len-1] )
	{
		case 'd':
			if ( word[len-3]=='i' && word[len-2]=='e' )
				IED_ACTION
			break;
		case 's':
			if ( SUFF4 ( 's', 's', 'e', 's' ) ) // faster that suff4a for some reason!
				len -= 2;
			else if ( word[len-3]=='i' && word[len-2]=='e' )
				IED_ACTION
			else if ( word[len-2]!='u' && word[len-2]!='s' )
			{
#ifdef SNOWBALL2011
				if ( first_vowel<=len-3 )
#endif

				len--;
			}
			break;
	}

	///////////
	// STEP 1B
	///////////

	i = 0;
	switch ( word[len-1] )
	{
		case 'd':
			if ( SUFF3A ( 'e', 'e' ) )				{ if ( len-3>=r1 ) len--; break; }
			if ( word[len-2]=='e' )					i = 2;
			break;

		case 'y':
			if ( word[len-2]=='l' )
			{
				if ( SUFF5A ( 'e', 'e', 'd', 'l' ) )	{ if ( len-5>=r1 ) len -= 3; break; }
				if ( SUFF4A ( 'e', 'd', 'l' ) )			{ i = 4; break; }
				if ( SUFF5A ( 'i', 'n', 'g', 'l' ) )	{ i = 5; break; }
			}
			break;

		case 'g':
			if ( SUFF3A ( 'i', 'n' ) )				i = 3;
			break;
	}

	if ( i && first_vowel<len-i )
	{
		len -= i;
		if ( SUFF2 ( 'a', 't' ) || SUFF2 ( 'b', 'l' ) || SUFF2 ( 'i', 'z' ) )
			word[len++] = 'e';
		else if ( len>=2 && word[len-1]==word[len-2] && stem_en_id ( word[len-1] ) )
			len--;
		else if ( ( len==2 && is_vowel(0) && !is_vowel(1) )
			|| ( len==r1 && !is_vowel ( len-3 ) && is_vowel ( len-2 ) && !stem_en_ivwxy ( word[len-1] ) ) )
		{
			word[len++] = 'e';
		}
	}

	///////////
	// STEP 1C
	///////////

	if ( len>2
		&& ( word[len-1]=='y' || word[len-1]=='Y' )
		&& !is_vowel ( len-2 ) )
	{
		word[len-1] = 'i';
	}

	//////////
	// STEP 2
	//////////

	if ( len-2>=r1 )
		switch ( word[len-1] )
	{
		case 'i':
			if ( len>=3 && ( W ( 2, 'c' ) || W ( 2, 'l' ) || W ( 2, 't' ) ) )
			{
				if ( SUFF4A ( 'e', 'n', 'c' ) )				{ if ( len-4>=r1 ) word[len-1] = 'e'; break; }
				if ( SUFF4A ( 'a', 'n', 'c' ) )				{ if ( len-4>=r1 ) word[len-1] = 'e'; break; }
				if ( SUFF4A ( 'a', 'b', 'l' ) )				{ if ( len-4>=r1 ) word[len-1] = 'e'; break; }
				if ( SUFF3A ( 'b', 'l' ) )					{ if ( len-3>=r1 ) word[len-1] = 'e'; break; }

				if ( SUFF5A ( 'e', 'n', 't', 'l' ) )		{ if ( len-5>=r1 ) len -= 2; break; }
				if ( SUFF5A ( 'a', 'l', 'i', 't' ) )		{ if ( len-5>=r1 ) len -= 3; break; }
				if ( SUFF5A ( 'o', 'u', 's', 'l' ) )		{ if ( len-5>=r1 ) len -= 2; break; }

				if ( SUFF5A ( 'i', 'v', 'i', 't' ) )		{ if ( len-5>=r1 ) { word[len-3] = 'e'; len -= 2; } break; }
				if ( SUFF6A ( 'b', 'i', 'l', 'i', 't' ) )	{ if ( len-6>=r1 ) { word[len-5] = 'l'; word[len-4] = 'e'; len -= 3; } break; }
				if ( SUFF5A ( 'f', 'u', 'l', 'l' ) )		{ if ( len-5>=r1 ) len -= 2; break; }
				if ( SUFF6A ( 'l', 'e', 's', 's', 'l' ) )	{ if ( len-6>=r1 ) len -= 2; break; }
			}

#ifdef SNOWBALL2011
			if ( len-3>=r1 && SUFF3A ( 'o', 'g' ) && word[len-4]=='l' ) { len -= 1; break; }
#else
			if ( len-3>=r1 && SUFF3A ( 'o', 'g' ) ) { len -= 1; break; }
#endif

			if ( len-2>=r1 && word[len-2]=='l' )
				len -= 2;
			else
				break;

			if ( len-2>=r1 && SUFF2 ( 'a', 'l' ) )
			{
				len -= 2;
				if ( len-5>=r1 && SUFF5 ( 'a', 't', 'i', 'o', 'n' ) )
				{
					len -= 3;
					word[len++] = 'e';
					break;
				}
				if ( SUFF4 ( 't', 'i', 'o', 'n' ) )
					break;
				len += 2;
			} else
			{
				switch ( word[len-1] )
				{
					case 'b':
					case 'c':
					case 'd':
					case 'e':
					case 'g':
					case 'h':
					case 'k':
					case 'm':
					case 'n':
					case 'r':
					case 't':
						break;
					default:
						len += 2;
						break;
				}
			}
			break;

		case 'l':
			if ( SUFF7A ( 'a', 't', 'i', 'o', 'n', 'a' ) )	{ if ( len-7>=r1 ) { word[len-5] = 'e'; len -= 4; } break; }
			if ( SUFF6A ( 't', 'i', 'o', 'n', 'a' ) )		{ if ( len-6>=r1 ) len -= 2; break; }
			break;

		case 'm':
			if ( SUFF5A ( 'a', 'l', 'i', 's' ) )			{ if ( len-5>=r1 ) len -= 3; break; }
			break;

		case 'n':
			if ( SUFF7A ( 'i', 'z', 'a', 't', 'i', 'o' ) )	{ if ( len-7>=r1 ) { word[len-5] = 'e'; len -= 4; } break; }
			if ( SUFF5A ( 'a', 't', 'i', 'o' ) )			{ if ( len-5>=r1 ) { word[len-3] = 'e'; len -= 2; } break; }
			break;

		case 'r':
			if ( SUFF4A ( 'i', 'z', 'e' ) )	{ if ( len-4>=r1 ) len -= 1; break; }
			if ( SUFF4A ( 'a', 't', 'o' ) )	{ if ( len-4>=r1 ) { word[len-2] = 'e'; len -= 1; } break; }
			break;

		case 's':
			if ( len-7>=r1 && (
				SUFF7A ( 'f', 'u', 'l', 'n', 'e', 's' ) ||
				SUFF7A ( 'o', 'u', 's', 'n', 'e', 's' ) ||
				SUFF7A ( 'i', 'v', 'e', 'n', 'e', 's' ) ) )
			{
				len -= 4;
			}
			break;
	}

	//////////
	// STEP 3
	//////////

	if ( len-3>=r1 )
		switch ( word[len-1] )
	{
		case 'e':
			if ( SUFF5A ( 'a', 'l', 'i', 'z' ) )	{ if ( len-5>=r1 ) len -= 3; break; }
			if ( SUFF5A ( 'i', 'c', 'a', 't' ) )	{ if ( len-5>=r1 ) len -= 3; break; }
#ifdef SNOWBALL2011
			if ( SUFF5A ( 'a', 't', 'i', 'v' ) )	{ if ( len-5>=r2 ) len -= 5; break; }
#else
			if ( SUFF5A ( 'a', 't', 'i', 'v' ) )	{ if ( len-5>=r1 ) len -= 5; break; }
#endif
			break;

		case 'i':
			if ( SUFF5A ( 'i', 'c', 'i', 't' ) )	{ if ( len-5>=r1 ) len -= 3; break; }
			break;

		case 'l':
			if ( SUFF4A ( 'i', 'c', 'a' ) )			{ if ( len-4>=r1 ) len -= 2; break; }
			if ( SUFF3A ( 'f', 'u' ) )				{ len -= 3; break; }
			break;

		case 's':
			if ( SUFF4A ( 'n', 'e', 's' ) )			{ if ( len-4>=r1 ) len -= 4; break; }
			break;
	}

	//////////
	// STEP 4
	//////////

	if ( len-2>=r2 )
		switch ( word[len-1] )
	{
		case 'c':
			if ( word[len-2]=='i' ) len -= 2; // -ic
			break;

		case 'e':
			if ( len-3>=r2 )
			{
				if ( SUFF4A ( 'a', 'n', 'c' ) )		{ if ( len-4>=r2 ) len -= 4; break; }
				if ( SUFF4A ( 'e', 'n', 'c' ) )		{ if ( len-4>=r2 ) len -= 4; break; }
				if ( SUFF4A ( 'a', 'b', 'l' ) )		{ if ( len-4>=r2 ) len -= 4; break; }
				if ( SUFF4A ( 'i', 'b', 'l' ) )		{ if ( len-4>=r2 ) len -= 4; break; }
				if ( SUFF3A ( 'a', 't' ) )			{ len -= 3; break; }
				if ( SUFF3A ( 'i', 'v' ) )			{ len -= 3; break; }
				if ( SUFF3A ( 'i', 'z' ) )			{ len -= 3; break; }
			}
			break;

		case 'i':
			if ( SUFF3A ( 'i', 't' ) )				{ if ( len-3>=r2 ) len -= 3; break; }
			break;

		case 'l':
			if ( word[len-2]=='a' ) len -= 2; // -al
			break;

		case 'm':
			if ( SUFF3A ( 'i', 's' ) )				{ if ( len-3>=r2 ) len -= 3; break; }
			break;

		case 'n':
			if ( len-3>=r2 && SUFF3 ( 'i', 'o', 'n' ) && ( word[len-4]=='t' || word[len-4]=='s' ) )
				len -= 3;
			break;

		case 'r':
			if ( word[len-2]=='e' ) len -= 2; // -er
			break;

		case 's':
			if ( SUFF3A ( 'o', 'u' ) )				{ if ( len-3>=r2 ) len -= 3; break; }
			break;

		case 't':
			if ( word[len-2]=='n' )
			{
				if ( SUFF5A ( 'e', 'm', 'e', 'n' ) )	{ if ( len-5>=r2 ) len -= 5; break; }
				if ( SUFF4A ( 'm', 'e', 'n' ) )			{ if ( len-4>=r2 ) len -= 4; break; }
				if ( SUFF3A ( 'a', 'n' ) )				{ if ( len-3>=r2 ) len -= 3; break; }
				if ( SUFF3A ( 'e', 'n' ) )				{ if ( len-3>=r2 ) len -= 3; break; }
			}
			break;
	}

	//////////
	// STEP 5
	//////////

#ifdef SNOWBALL2011
	if ( len>r2 && word[len-1]=='l' && word[len-2]=='l' )
		len--;
	else
#endif
	while ( word[len-1]=='e' )
	{
		if ( len>r2 )
		{
			len--;
			break;
		}
		if ( len<=r1 )
			break;
		if ( len>3 && !is_vowel ( len-4 ) && is_vowel ( len-3 ) && !stem_en_ivwxy ( word[len-2] ) )
			break;
		if ( len==3 && is_vowel(0) && !is_vowel(1) )
			break;
		len--;
		break;
	}
#ifndef SNOWBALL2011
	if ( len>r2 && word[len-1]=='l' && word[len-2]=='l' )
		len--;
#endif

	////////////
	// FINALIZE
	////////////

	word[len] = 0;
	if ( has_Y )
		for ( i=0; i<len; i++ )
			if ( word[i]=='Y' )
				word[i] = 'y';
}

