#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);
}

TxtLoc next_newline(Txt *t, TxtLoc l) {
	do l = txt_next(t, l);
	while (!txt_at_end(t, l) && txt_byte(t, l) != '\n');
	return l;
}

TxtLoc prev_newline(Txt *t, TxtLoc l) {
	do l = txt_prev(t, l);
	while (!txt_at_start(t, l) && txt_byte(t, l) != '\n');
	return l;
}

TxtLoc start_of_line(Txt *t, TxtLoc l) {
	l = prev_newline(t, l);
	if (!txt_at_start(t,l) && txt_byte(t, l) == '\n') l = txt_next(t, l);
	return l;
}

TxtLoc prev_line(Txt *t, TxtLoc l) {
	TxtLoc start = start_of_line(t, l);
	u32 n = 0;
	for (TxtLoc tmp = start; txt_before(tmp, l); txt_chr_next(t, &tmp)) n++;
	TxtLoc start_up = start_of_line(t, txt_prev(t, start));
	while (n--) {
		if (txt_chr_next(t, &start_up) == '\n') {
			start_up = txt_prev(t, start_up);
			break;
		}
	}
	return start_up;
}

TxtLoc next_line(Txt *t, TxtLoc l) {
	TxtLoc start = start_of_line(t, l);
	u32 n = 0;
	for (TxtLoc tmp = start; txt_before(tmp, l); txt_chr_next(t, &tmp)) n++;
	TxtLoc start_dn = txt_byte(t, l) == '\n' ? txt_next(t, l) : txt_next(t, next_newline(t, l));
	while (n--) {
		if (txt_chr_next(t, &start_dn) == '\n') {
			start_dn = txt_prev(t, start_dn);
			break;
		}
	}
	return start_dn;
}

u32 move_line_up(Txt *t, u32 cur) {
	return txt_ofs(t, prev_line(t, txt_at(t, cur)));
}

u32 move_line_down(Txt *t, u32 cur) {
	return txt_ofs(t, next_line(t, txt_at(t, cur)));
}

int empty_line(Txt *t, TxtLoc l) {
	return txt_byte(t, start_of_line(t, l)) == '\n';
}

TxtLoc next_par(Txt *t, TxtLoc l) {
	while (!txt_at_end(t, l) && empty_line(t, l)) l = next_line(t, l);
	while (!txt_at_end(t, l) && !empty_line(t, l)) l = next_line(t, l);
	return l;
}

TxtLoc prev_par(Txt *t, TxtLoc l) {
	while (!txt_at_start(t, l) && empty_line(t, l)) l = prev_line(t, l);
	while (!txt_at_start(t, l) && !empty_line(t, l)) l = prev_line(t, l);
	return l;
}

u32 move_par_up(Txt *t, u32 cur) {
	return txt_ofs(t, prev_par(t, txt_at(t, cur)));
}

u32 move_par_down(Txt *t, u32 cur) {
	return txt_ofs(t, next_par(t, txt_at(t, cur)));
}

/* main */

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

void find_view_window(Txt *t, u32 curs, TxtLoc *start, TxtLoc *end) {
	TxtLoc l = txt_at(t, curs);
	u32 n = LINES;
	u32 u = LINES / 2;
	TxtLoc a = l;
	for (u32 i = 0; i < u; i++) a = prev_newline(t, a);
	TxtLoc b = a;
	while (!txt_at_end(t, b) && n--) b = next_newline(t, b);
	if (!txt_at_start(t,a) && txt_byte(t,a) == '\n') a = txt_next(t, a);
	*start = a;
	*end = b;
}

void draw(void *ctx) {
	(void)ctx;
	vui_clear();
	int x = 0, y = 0;
	TxtLoc start, end;
	find_view_window(&txt, cur, &start, &end);

	vui_aprintf(-1, 0, ODD_ATTR, "%u piece(s)", txt.ptbl.n);
	for (u32 i = 0; i < txt.ptbl.n; i++) {
		TxtPiece *p = &txt.ptbl.v[i];
		VuiAttr a = i&1 ? ODD_ATTR : EVEN_ATTR;
		vui_aprintf(-1, i+1, a, "%u, %u (%s)", p->ofs, p->n, p->buf == TXT_ADD ? "add" : "src");
	}

	TxtLoc l = txt_at(&txt, cur);
	int cur_found = 0;
	vui_printf(-1, -3, "(%u.%u)-(%u.%u)", start.p, start.i, end.p, end.i);
	while (txt_before(start, end)) {
		if (l.p == start.p && l.i == start.i) {
			cur_found = 1;
			vui_curs_pos(x, y);
		}
		u32 c = txt_chr_next(&txt, &start);
		if (c == '\n') {
			x = 0;
			y++;
		} else if (c == '\t') {
			x++;
			x += (-x & 7);
		} else if (c) {
			vui_chr(x++, y, c);
		}
	}
	ASSERT(start.i <= txt.ptbl.v[start.p].n);
	vui_printf(-1, -4, "end(%u.%u)", start.p, start.i);
	if (!cur_found) vui_curs_pos(x, y);
	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(int argc, const char **argv) {
	scratch = arena_init(1L << 20);
	vui_init();
	vui_curs_vis(1);
	vui_redraw_fn(draw);
	const char *path = "test.txt";
	if (argc > 1) path = argv[1];
	if (txt_load(&txt, path)) 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 KEY_UP:
			cur = move_line_up(&txt, cur);
			break;
		case KEY_DOWN:
			cur = move_line_down(&txt, cur);
			break;
		case KEY_UP | KEY_CTRL_BIT:
			cur = move_par_up(&txt, cur);
			break;
		case KEY_DOWN | KEY_CTRL_BIT:
			cur = move_par_down(&txt, cur);
			break;
		case KEY_PGUP:
			for (u32 i = 0; i < LINES; i += 3) cur = move_line_up(&txt, cur);
			break;
		case KEY_PGDN:
			for (u32 i = 0; i < LINES; i += 3) cur = move_line_down(&txt, cur);
			break;
		case KEY_HOME:
			cur = txt_ofs(&txt, start_of_line(&txt, txt_at(&txt, cur)));
			break;
		case KEY_END:
			cur = txt_ofs(&txt, next_newline(&txt, txt_at(&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, path);
                        //txt_load(&txt, "test.txt");
			break;
		case '\r': {
			u32 tabs = 0;
			TxtLoc start = start_of_line(&txt, txt_at(&txt, cur));
			for (TxtLoc l = start; txt_byte(&txt, l) == '\t'; l = txt_next(&txt, l))
				tabs++;
			while (txt_byte(&txt, txt_at(&txt, cur - 1)) == '\t') {
				cur = txt_delete(&txt, cur, 1);
			}
			cur = txt_insert_c(&txt, cur, '\n');
			while (tabs--) cur = txt_insert_c(&txt, cur, '\t');
		} break;
		default:
			if ((c == '\t' || c >= ' ') && c <= KEY_UTF8_MAX) cur = txt_insert_c(&txt, cur, c);
			break;
		}
	}
brk:
	vui_fini();
	arena_free(&scratch);
	return 0;
}