#include "imtable.h"
#define IM_BUFFER_LEN 32
char im_buffer[IM_BUFFER_LEN];
char im_buffer_pos = 0;
//recursive search, returns -1 on failure
//searches from [start, end)
int im_search(char * input, int start, int end) {
	// 0 width search
	if (end <= start) {
		return -1;
	}
	//test for middle, works even for 1 width middle=start
	int middle = start + (end-start)/2;
	printf("testing:%s\n",im_table[middle][0]);
	int test = strncmp(im_table[middle][0], input, IM_TABLE_ENTRY_LEN);
	if (test == 0) {
		return middle;
	}
	//special case for width 1,2 region
	if ((end - start) == 1) {
		if (test == 0) {
			return start;
		} else {
			return -1;
		}
	}
	if (test == 0) {
		return 0;
	} else {
		if (test > 0) {
			return im_search(input,start,middle);
		} else {
			return im_search(input,middle,end);
		}
	}
	
}
//returns output len, since we want to be able to handle null bytes as well
int update_im_state(char input, char * output) {
	if ( ('a' <= input <= 'z')||('0' <= input <= '9')||(input == ' ') ) {
		if (im_buffer_pos < IM_BUFFER_LEN) {
			im_buffer[im_buffer_pos] = input;
			im_buffer_pos++;
		} else {
			//passthrough
			output[0] = input;
			output[1] = 0;
			return 1;
		}
	}
	int im_entry = im_search(im_buffer,0, IM_TABLE_LEN);
	if (im_entry != -1) {
		strncpy(output, im_table[im_entry][1], IM_TABLE_ENTRY_LEN);
		im_buffer[0] = 0;
		im_buffer_pos = 0;
		return strlen(im_table[im_entry][1]);
	}
	//these only do something if there's something in the buffer, otherwise
	//passthrough
	if (im_buffer_pos > 0) {
		switch (input) {
			//escape, cancels
			case 0x1B:
				im_buffer[0] = 0;
				im_buffer_pos = 0;
				return 0;
			break;
			//enter, enters the buffer
			case 0x0A:
				for (int i = 0; i <im_buffer_pos; i++) {
					output[i] = im_buffer[i];
				}
				output[im_buffer_pos] = 0;
				int tmp = im_buffer_pos;
				im_buffer_pos = 0;
				return tmp;
			break;
			//backspace
			case 0x08:
				if (im_buffer_pos > 0) {
					im_buffer_pos--;
					im_buffer[im_buffer_pos] = 0;
				}
				return 0;
			break;
		}
	}
	//default behavior of passthrough
	output[0] = input;
	output[1] = 0;
	return 1;
	
}