//#include "imtable.h"
#include "boshiamy.h"
#define IM_BUFFER_LEN 32
#define ENTER_KEY 0x0D
#define BACKSPACE_KEY 0x7F
//#define BACKSPACE_KEY '+'
//setting it to the actual escape character interferes with arrow keys and
//whatnot
//#define ESCAPE_KEY 0x1B
#define ESCAPE_KEY '`'
//Vertical Tab Ctrl+K
#define TOGGLE_KEY 0x0B
char im_buffer[IM_BUFFER_LEN+1];
char im_buffer_pos = 0;
int im_on = 1;
//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 (input == TOGGLE_KEY) {
		im_on = !im_on;
		//clears the im buffer if its toggling off
		if (!im_on) {
			im_buffer[0] = 0;
			im_buffer_pos = 0;
		}
	}
	//just exit if the im is off
	if (!im_on) {
		output[0] = input;
		output[1] = 0;
		return 1;
	}
	if ( ('a' <= input && input <= 'z')||('0' <= input && input  <= '9') ||(input == ' ') || (input == ',') || (input == '.')) {
		if ( (im_buffer_pos < IM_BUFFER_LEN) && (im_buffer_pos < IM_TABLE_ENTRY_LEN) ){
			im_buffer[im_buffer_pos] = input;
			im_buffer_pos++;
			im_buffer[im_buffer_pos] = 0;
		} else {
			//passthrough
			output[0] = input;
			output[1] = 0;
			return 1;
		}
		//if there's a match return it
		int im_entry = im_search(im_buffer, 0, IM_TABLE_LEN);
		if (im_entry != -1) {
			//clear the buffer
			im_buffer[0] = 0;
			im_buffer_pos = 0;
			strncpy(output, im_table[im_entry][1], IM_TABLE_ENTRY_LEN);
			return strlen(im_table[im_entry][1]);
		}
	} else {
		//these only do something if there's something in the buffer, otherwise
		//passthrough
		if (im_buffer_pos > 0) {
			switch (input) {
				//escape, cancels
				case ESCAPE_KEY:
					im_buffer[0] = 0;
					im_buffer_pos = 0;
					return 0;
				break;
				//enter, enters the buffer
				case ENTER_KEY:
					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 BACKSPACE_KEY:
					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;
	}
	
}