/* ref:
https://stackoverflow.com/questions/21737906/how-to-read-write-utf8-text-files-in-c
*/

#include <stdio.h>
#include <wchar.h>
#include "wtable.h"

/*
#define WSEARCH_DEBUG
*/

wint_t wchar2ata[][2] = {
	/* Unicode, ATASCII */
	{ 0x2190, 0x1e },
	{ 0x2191, 0x1c },
	{ 0x2192, 0x1f },
	{ 0x2193, 0x1d },
	{ 0x21b0, 0x7d },
	{ 0x241b, 0x1b },
	{ 0x2501, 0x12 },
	{ 0x2503, 0x02 },
	{ 0x250f, 0x11 },
	{ 0x2513, 0x05 },
	{ 0x2517, 0x1a },
	{ 0x251b, 0x03 },
	{ 0x2523, 0x01 },
	{ 0x252b, 0x04 },
	{ 0x2533, 0x17 },
	{ 0x253b, 0x18 },
	{ 0x254b, 0x13 },
	{ 0x2571, 0x06 },
	{ 0x2572, 0x07 },
	{ 0x2581, 0x0e },
	{ 0x2584, 0x15 },
	{ 0x258c, 0x19 },
	{ 0x258e, 0x16 },
	{ 0x2594, 0x0d },
	{ 0x2596, 0x0f },
	{ 0x2597, 0x09 },
	{ 0x2598, 0x0c },
	{ 0x259d, 0x0b },
	{ 0x25b6, 0x7f },
	{ 0x25c0, 0x7e },
	{ 0x25c6, 0x60 },
	{ 0x25cf, 0x14 },
	{ 0x25e2, 0x08 },
	{ 0x25e3, 0x0a },
	{ 0x2660, 0x7b },
	{ 0x2663, 0x10 },
	{ 0x2665, 0x00 },
};

wint_t wchar2ics[][2] = {
	/* Unicode, ATASCII */
	{ 0x00a1, 0x60 },
	{ 0x00a3, 0x08 },
	{ 0x00c4, 0x7b },
	{ 0x00c9, 0x03 },
	{ 0x00d1, 0x02 },
	{ 0x00d6, 0x0c },
	{ 0x00dc, 0x10 },
	{ 0x00e0, 0x19 },
	{ 0x00e1, 0x00 },
	{ 0x00e2, 0x11 },
	{ 0x00e4, 0x0b },
	{ 0x00e7, 0x04 },
	{ 0x00e8, 0x15 },
	{ 0x00e9, 0x14 },
	{ 0x00ea, 0x17 },
	{ 0x00ec, 0x07 },
	{ 0x00ee, 0x13 },
	{ 0x00ef, 0x09 },
	{ 0x00f1, 0x16 },
	{ 0x00f2, 0x06 },
	{ 0x00f3, 0x0e },
	{ 0x00f4, 0x05 },
	{ 0x00f6, 0x0f },
	{ 0x00f9, 0x01 },
	{ 0x00fa, 0x0d },
	{ 0x00fb, 0x12 },
	{ 0x00fc, 0x0a },
	{ 0x0226, 0x1a },
	{ 0x0227, 0x18 },
	{ 0x2190, 0x1e },
	{ 0x2191, 0x1c },
	{ 0x2192, 0x1f },
	{ 0x2193, 0x1d },
	{ 0x21b0, 0x7d },
	{ 0x241b, 0x1b },
	{ 0x25b6, 0x7f },
	{ 0x25c0, 0x7e },
};

static int tblsize = sizeof(wchar2ata) / sizeof(wchar2ata[0]);

static wint_t wsearch(wint_t table[][2], wint_t target, int start, int end) {
	wint_t *elem;
	int center;

#ifdef WSEARCH_DEBUG
	fprintf(stderr, "wsearch(0x%04x, %d, %d)\n", target, start, end);
#endif

	if(start == end) {
		if(table[start][0] == target)
			return table[start][1];
		else
			return -1;
	} else {
		center = (start + end) / 2;
		elem = table[center];

#ifdef WSEARCH_DEBUG
		fprintf(stderr, "elem = 0x%04x, 0x%02x\n", elem[0], elem[1]);
#endif

		if(elem[0] == target)
			return elem[1];
		else if(elem[0] > target)
			return wsearch(table, target, start, center);
		else
			return wsearch(table, target, center + 1, end);
	}
}

int wchar2atascii(wint_t wc, int ics) {
	return wsearch((ics ? wchar2ics : wchar2ata), wc, 0, tblsize - 1);
}

#ifdef WSEARCH_DEBUG
int main(int argc, char **argv) {
	printf("%02x\n", wchar2atascii(0x2190, 0));
	printf("%02x\n", wchar2atascii(0x2571, 0));
	printf("%02x\n", wchar2atascii(0x25c6, 0));
	printf("%02x\n", wchar2atascii(0x2665, 0));
	printf("%02x\n", wchar2atascii(0x2510, 0));
	return 0;
}
#endif