/*
** Arabtype Copyright 2012-2015(c) Wael El Oraiby. All Rights Reserved
**
** This library 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.

** Under Section 7 of GPL version 3, you are granted additional
** permissions described in the GCC Runtime Library Exception, version
** 3.1, as published by the Free Software Foundation.

** You should have received a copy of the GNU General Public License and
** a copy of the GCC Runtime Library Exception along with this program;
** see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
** <http://www.gnu.org/licenses/>.
**
** see README.md file for more information
*/

#include <stdbool.h>
#include <stdio.h>
#include "utf8.h"
#include "arabtype.h"

#define ARABIC_LETTER_START     0x621
#define ARABIC_LETTER_END       0x64A

#define TASHKIL_LETTER_START    0x64B
#define TASHKIL_LETTER_END      0x652

#define ISOLATED    0
#define ENDING      1
#define INITIAL     2
#define MEDIAL      3

#define UNICODE_LAM	0x644


//
// 0: isolated form
// 1: ending form
// 2: beginning form	(if 0, it's a cutting type)
// 3: middle form
//
typedef uint32_t	char_form_t[4];
typedef char_form_t	all_form_t[2];

static all_form_t arabic_forms_b[]	= {
	{ {0xFE80, 0xFE80,      0,      0}, {-1, -1, 0, 0} },		// hamza	(0)
	{ {0xFE81, 0xFE82,      0,      0}, {-1, -1, 0xFEF5, 0xFEF6} },	// 2alif madda	(1)
	{ {0xFE83, 0xFE84,      0,      0}, {-1, -1, 0xFEF7, 0xFEF8} },	// 2alif hamza	(2)
	{ {0xFE85, 0xFE86,      0,      0}, {-1, -1, 0, 0} },		// waw hamza	(3)
	{ {0xFE87, 0xFE88,      0,      0}, {-1, -1, 0xFEF9, 0xFEFA} },	// 2alif hamza maksoura	(4)
	{ {0xFE89, 0xFE8A, 0xFE8B, 0xFE8C}, {-1, -1, 0, 0} },		// 2alif maqsoura hamza	(5)
	{ {0xFE8D, 0xFE8E,      0,      0}, {-1, -1, 0xFEFB, 0xFEFC} },	// 2alif	(6)
	{ {0xFE8F, 0xFE90, 0xFE91, 0xFE92}, {-1, -1, 0, 0} },		// ba2		(7)
	{ {0xFE93, 0xFE94,      0,      0}, {-1, -1, 0, 0} },		// ta2 marbouta	(8)
	{ {0xFE95, 0xFE96, 0xFE97, 0xFE98}, {-1, -1, 0, 0} },		// ta2		(9)
	{ {0xFE99, 0xFE9A, 0xFE9B, 0xFE9C}, {-1, -1, 0, 0} },		// tha2		(10)
	{ {0xFE9D, 0xFE9E, 0xFE9F, 0xFEA0}, {-1, -1, 0, 0} },		// jim		(11)
	{ {0xFEA1, 0xFEA2, 0xFEA3, 0xFEA4}, {-1, -1, 0, 0} },		// 7a2		(12)
	{ {0xFEA5, 0xFEA6, 0xFEA7, 0xFEA8}, {-1, -1, 0, 0} },		// kha2		(13)
	{ {0xFEA9, 0xFEAA,      0,      0}, {-1, -1, 0, 0} },		// dal		(14)
	{ {0xFEAB, 0xFEAC,      0,      0}, {-1, -1, 0, 0} },		// dhal		(15)
	{ {0xFEAD, 0xFEAE,      0,      0}, {-1, -1, 0, 0} },		// ra2		(16)
	{ {0xFEAF, 0xFEB0,      0,      0}, {-1, -1, 0, 0} },		// zayn		(17)
	{ {0xFEB1, 0xFEB2, 0xFEB3, 0xFEB4}, {-1, -1, 0, 0} },		// syn		(18)
	{ {0xFEB5, 0xFEB6, 0xFEB7, 0xFEB8}, {-1, -1, 0, 0} },		// shin		(19)
	{ {0xFEB9, 0xFEBA, 0xFEBB, 0xFEBC}, {-1, -1, 0, 0} },		// sad		(20)
	{ {0xFEBD, 0xFEBE, 0xFEBF, 0xFEC0}, {-1, -1, 0, 0} },		// dad		(21)
	{ {0xFEC1, 0xFEC2, 0xFEC3, 0xFEC4}, {-1, -1, 0, 0} },		// tah		(22)
	{ {0xFEC5, 0xFEC6, 0xFEC7, 0xFEC8}, {-1, -1, 0, 0} },		// thah		(23)
	{ {0xFEC9, 0xFECA, 0xFECB, 0xFECC}, {-1, -1, 0, 0} },		// 3ayn		(24)
	{ {0xFECD, 0xFECE, 0xFECF, 0xFED0}, {-1, -1, 0, 0} },		// ghayn	(25)
	{ {     0,      0,      0,      0}, {-1, -1, 0, 0} },		//		(26)
	{ {     0,      0,      0,      0}, {-1, -1, 0, 0} },		//		(27)
	{ {     0,      0,      0,      0}, {-1, -1, 0, 0} },		//		(28)
	{ {     0,      0,      0,      0}, {-1, -1, 0, 0} },		//		(29)
	{ {     0,      0,      0,      0}, {-1, -1, 0, 0} },		//		(30)
	{ { 0x640,  0x640,  0x640,  0x640}, {-1, -1, 0, 0} },		// wasla	(31)
	{ {0xFED1, 0xFED2, 0xFED3, 0xFED4}, {-1, -1, 0, 0} },		// fa2		(32)
	{ {0xFED5, 0xFED6, 0xFED7, 0xFED8}, {-1, -1, 0, 0} },		// qaf		(33)
	{ {0xFED9, 0xFEDA, 0xFEDB, 0xFEDC}, {-1, -1, 0, 0} },		// kaf		(34)
	{ {0xFEDD, 0xFEDE, 0xFEDF, 0xFEE0}, {-1, -1, 0, 0} },		// lam		(35)
	{ {0xFEE1, 0xFEE2, 0xFEE3, 0xFEE4}, {-1, -1, 0, 0} },		// mim		(36)
	{ {0xFEE5, 0xFEE6, 0xFEE7, 0xFEE8}, {-1, -1, 0, 0} },		// noon		(37)
	{ {0xFEE9, 0xFEEA, 0xFEEB, 0xFEEC}, {-1, -1, 0, 0} },		// ha2		(38)
	{ {0xFEED, 0xFEEE,      0,      0}, {-1, -1, 0, 0} },		// waw		(39)
	{ {0xFEEF, 0xFEF0,      0,      0}, {-1, -1, 0, 0} },		// 2alif maksoura	(40)
	{ {0xFEF1, 0xFEF2, 0xFEF3, 0xFEF4}, {-1, -1, 0, 0} },		// ya2		(41)
};



static inline bool is_arabic_letter(uint32_t cp)		{ return ( cp >= ARABIC_LETTER_START && cp <=  ARABIC_LETTER_END ); }
static inline bool is_tashkil_letter(uint32_t cp)		{ return ( cp >= TASHKIL_LETTER_START && cp <=  TASHKIL_LETTER_END ); }
static inline bool is_lam_alef(uint32_t cp, uint32_t next)	{ return cp == UNICODE_LAM &&
									 is_arabic_letter(next) &&
									 arabic_forms_b[next - ARABIC_LETTER_START][1][INITIAL] != 0; }
static inline bool is_alef_prev_lam(uint32_t prev, uint32_t cp)	{ return prev == UNICODE_LAM &&
									 is_arabic_letter(cp) &&
									 arabic_forms_b[cp - ARABIC_LETTER_START][1][INITIAL] != 0; }

static inline bool is_linking_type(uint32_t cp) { return is_arabic_letter(cp) && arabic_forms_b[cp - ARABIC_LETTER_START][0][MEDIAL] != 0; }


static uint32_t
get_presentation_form_b_of_char(uint32_t prev, uint32_t next, uint32_t cp) {

	if( !is_arabic_letter(cp) ) {
		return cp;	/* not an Arabic letter */
	}

	bool	is_la	= is_lam_alef(cp, next);
	bool	is_apl	= is_alef_prev_lam(prev, cp);

	bool	is_lapl	= is_la | is_apl;

#ifdef CLEAR_CODE
	if( is_lapl ) {
		uint32_t index	= (is_linking_type(cp) << 1) | is_linking_type(prev);
		return arabic_forms_b[next -  ARABIC_LETTER_START][is_lapl][index];

	} else {
		if( is_apl ) {
			return -1;	// skip previously processed lam alef
		} else {
			uint32_t index	= ((is_arabic_letter(next) & is_linking_type(cp)) << 1) | is_linking_type(prev);

			return arabic_forms_b[cp -  ARABIC_LETTER_START][is_lapl][index];
		}
	}
#else
	// optimized code
	uint32_t index	= (((is_lapl | is_arabic_letter(next)) & is_linking_type(cp)) << 1) | is_linking_type(prev);
	uint32_t ref	= next * is_la + cp * (!is_la) - ARABIC_LETTER_START;
	return arabic_forms_b[ref][is_lapl][index];
#endif
}

size_t
get_presentation_form_b(size_t in_len, unsigned char* in_str, size_t out_len, uint32_t* out_cp) {
	uint32_t codep	= 0;
	uint32_t state	= 0;
	uint32_t prev	= 0;
	size_t cp_count	= out_len / sizeof(uint32_t);
	size_t	o	= 0;

	for( size_t i = 0; i < in_len && o < cp_count; ++i ) {
		if( decode(&state, &codep, in_str[i]) == UTF8_ACCEPT ) {
			out_cp[o]	= codep;
			++o;
		}
	}

	if( state != UTF8_ACCEPT ) {
		// The string is not well-formed"
		return 0;
	}

	cp_count	= o;
	size_t		s	= 0;

	for( o = 0; o < cp_count; ++o) {
		uint32_t cp = out_cp[o];

		if (!is_tashkil_letter(cp)) {
			uint32_t next = o < cp_count - 1 ? out_cp[o + 1] : 0;

			if (is_tashkil_letter(next))
				next = (o + 1) < cp_count - 1 ? out_cp[o + 2] : 0;

			uint32_t tcp = get_presentation_form_b_of_char(prev, next, cp);
			if( tcp != (uint32_t)-1 ) {
				out_cp[s]	= tcp;
				++s;
			}
			prev	= cp;
		} else {
			out_cp[s]	= cp;
			++s;
		}
	}

	return o;
}