#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
#include <ctype.h>
#include <err.h>

#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>

#define ARENA_IMPL
#define UTF8_IMPL

#include "wrmr.h"
#include "arena.h"
#include "txt.h"
#include "vui.h"
#include "utf8.h"

Arena scratch = { 0 };
Txt txt = { 0 };
u32 cur = 0;

int is_space(u32 c) {
	return c <= 0x20 && c != 0;
}

u32 move_word_back(Txt *t, u32 cur) {
	TxtLoc l = txt_at(t, cur);
	while (!txt_at_start(t,l)) {
		TxtLoc n = txt_prev(t, l);
		if (!is_space(txt_chr(t, n))) break;
		l = n;
	}
	while (!txt_at_start(t,l)) {
		TxtLoc n = txt_prev(t, l);
		if (is_space(txt_chr(t, n))) break;
		l = n;
	}
	return txt_ofs(t, l);
}

u32 move_word_fwd(Txt *t, u32 cur) {
	TxtLoc l = txt_at(t, cur);
	while (!txt_at_end(t,l) && is_space(txt_chr(t, l))) l = txt_next(t, l);
	while (!txt_at_end(t,l) && !is_space(txt_chr(t, l))) l = txt_next(t, l);
	return txt_ofs(t, l);
}

u32 move_char_back(Txt *t, u32 cur) {
	while (cur > 0) {
		cur--;
		u8 c = txt_byte(t, txt_at(t, cur));
		if ((c & 0xc0) != 0x80) break;
	}
	return cur;
}

u32 move_char_fwd(Txt *t, u32 cur) {
	u8 b = txt_byte(t, txt_at(t, cur));
	u32 n = stdc_leading_ones(b);
	if (cur + n >= t->len) return t->len;
	return cur + n + !n;
}

u32 del_between(Txt *t, u32 a, u32 b) {
	if (b < a) { u32 t = a; a = b; b = t; }
	//if (b - a > 10) TRAP();
	return txt_delete(t, b, b - a);
}

/* main */

#define ODD_ATTR (FG_CYAN | BG_BLACK)
#define EVEN_ATTR (FG_WHITE | BG_BLACK)

void draw(void *ctx) {
	(void)ctx;
redraw:;
	vui_clear();
	static int max_y = 0;
	int x = 0, y = 0;
	u32 ofs = 0;
	for (u32 i = 0; i < txt.ptbl.n; i++) {
		Arena stk = scratch;
		TxtPiece *p = &txt.ptbl.v[i];
		const char *s = txt.buf[p->buf].s + p->ofs;

		u32 bufn = utf8_decode_len(s, p->n);
		u32 *buf = new_arr(&scratch, u32, bufn);
		utf8_decode(buf, s, bufn);

		VuiAttr a = i&1 ? ODD_ATTR : EVEN_ATTR;
		vui_aprintf(-1, i, a, "%u, %u (%s)", p->ofs, p->n, p->buf == TXT_ADD ? "add" : "src");

		for (u32 j = 0; j < bufn; j++) {
			u32 c = buf[j];
			if (ofs == cur) vui_curs_pos(x, y - (max_y - LINES + 1));
			if (c != '\r' && c != '\n') {
				vui_chra(x++, y - (max_y - LINES + 1), c, a);
			}
			if (c == '\n') {
				x = 0;
				y++;
			}
			ofs += UTF8_CP_LEN(c);
		}
		scratch = stk;
	}
	if (ofs == cur) vui_curs_pos(x, y - (max_y - LINES + 1));
	if (y > max_y) {
		max_y = y;
		goto redraw;
	}
	TxtLoc l = txt_at(&txt, cur);
	u32 c = txt_chr(&txt, l);
	vui_printf(-1, -1, "%u, %u - %02x (%c)", l.p, l.i, c, (c < 0x20 || c > 0x7e) ? ' ' : c);
	u32 used = scratch.beg - scratch.start, max = scratch.end - scratch.start;
	vui_printf(-1, -2, "scratch %.02f/%.02fk", used/1024.0, max/1024.0);
}

int main(void) {
	scratch = arena_init(1L << 20);
	vui_init();
	vui_curs_vis(1);
	vui_redraw_fn(draw);
	if (txt_load(&txt, "test.txt")) err(1, "couldn't open file");
	cur = txt.len;
	for (;;) {
		scratch.beg = scratch.start;
		draw(NULL);
		vui_blit();
		u32 c = vui_key();
		switch (c) {
		case KEY_ESC:
			goto brk;
		case KEY_BKSP:
			cur = txt_delete_c(&txt, cur);
			break;
		case KEY_LEFT:
			cur = move_char_back(&txt, cur);
			break;
		case KEY_LEFT | KEY_CTRL_BIT:
			cur = move_word_back(&txt, cur);
			break;
		case KEY_RIGHT:
			cur = move_char_fwd(&txt, cur);
			break;
		case KEY_RIGHT | KEY_CTRL_BIT:
			cur = move_word_fwd(&txt, cur);
			break;
		case 0x17 /* ^W */:
			cur = del_between(&txt, move_word_back(&txt, cur), cur);
			break;
		case 0x05 /* ^E */:
			cur = del_between(&txt, cur, move_word_fwd(&txt, cur));
			break;
		case 0x13 /* ^S */:
                        txt_save(&txt, "test.txt");
                        txt_load(&txt, "test.txt");
			break;
		case '\r':
			cur = txt_insert_c(&txt, cur, '\n');
			break;
		default:
			if (c >= ' ' && c <= KEY_UTF8_MAX) cur = txt_insert_c(&txt, cur, c);
			break;
		}
	}
brk:
	vui_fini();
	arena_free(&scratch);
	return 0;
}