#include <stdint.h>
#include <stddef.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 mode = 0;
u32 count = 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 end_of_line(Txt *t, TxtLoc l) {
	return next_newline(t, start_of_line(t, l));
}

u32 get_col(Txt *t, TxtLoc l) {
	u32 n = 0;
	for (TxtLoc tmp = start_of_line(t, l); txt_before(tmp, l); txt_chr_next(t, &tmp)) n++;
	return n;
}

TxtLoc at_col(Txt *t, TxtLoc l, u32 col) {
	l = start_of_line(t, l);
	while (col--) {
		if (txt_chr_next(t, &l) == '\n') {
			l = txt_prev(t, l);
			break;
		}
	}
	return l;
}

TxtLoc prev_line(Txt *t, TxtLoc l) {
	TxtLoc start = start_of_line(t, l);
	return at_col(t, txt_prev(t, start), get_col(t, l));
}

TxtLoc next_line(Txt *t, TxtLoc l) {
	TxtLoc end = end_of_line(t, l);
	if (txt_at_end(t, end)) return end;
	return at_col(t, txt_next(t, end), get_col(t, l));
}

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) {
	u8 b = txt_byte(t, start_of_line(t, l));
	return b == '\n' || b == 0 /* last line of buffer */;
}

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 u = LINES / 2;
	TxtLoc a = l;
	for (u32 i = 0; i < u; i++) a = prev_newline(t, a);
	u32 n = 0;
	TxtLoc b = a;
	while (!txt_at_end(t, b) && n++ < LINES) b = next_newline(t, b);
	while (!txt_at_start(t, a) && n++ < LINES) a = prev_newline(t, a);
	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;
	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);
	if (!cur_found) vui_curs_pos(x, y);
	u32 c = txt_chr(&txt, l);
	vui_printf(-1, -4, "%u", count);
	vui_aprintf(-1, -3, mode ? FG_BCYAN : FG_CYAN, "%s", mode ? "INSERT" : "NORMAL");
	vui_printf(-1, -1, "%u - %u.%u - %02x (%c)", cur, 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 motion(u32 c) {
	u32 last_cur = cur;
loop:
	switch (c) {
	case KEY_LEFT:
	case 'h':
		cur = move_char_back(&txt, cur);
		break;
	case KEY_LEFT | KEY_CTRL_BIT:
	case 'b':
		cur = move_word_back(&txt, cur);
		break;
	case KEY_RIGHT:
	case 'l':
		cur = move_char_fwd(&txt, cur);
		break;
	case KEY_RIGHT | KEY_CTRL_BIT:
	case 'w':
		cur = move_word_fwd(&txt, cur);
		break;
	case KEY_UP:
	case 'k':
		cur = move_line_up(&txt, cur);
		break;
	case KEY_DOWN:
	case 'j':
		cur = move_line_down(&txt, cur);
		break;
	case KEY_UP | KEY_CTRL_BIT:
	case '{':
		cur = move_par_up(&txt, cur);
		break;
	case KEY_DOWN | KEY_CTRL_BIT:
	case '}':
		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:
	case '^':
	case '0':
		cur = txt_ofs(&txt, start_of_line(&txt, txt_at(&txt, cur)));
		break;
	case KEY_END:
	case '$':
		cur = txt_ofs(&txt, next_newline(&txt, txt_at(&txt, cur)));
		break;
	case KEY_HOME | KEY_CTRL_BIT:
	case 'g':
		cur = 0;
		break;
	case KEY_END | KEY_CTRL_BIT:
	case 'G':
		cur = txt.len;
		break;
	case 'f': {
		u32 n = vui_key();
		TxtLoc l = txt_next(&txt, txt_at(&txt, cur));
		for (TxtLoc t = l;;) {
			u32 c = txt_chr_next(&txt, &t);
			if (c == '\n') break;
			if (c == n) {
				cur = txt_ofs(&txt, l);
				break;
			}
			l = t;
		}
	} break;
	case 'F': {
		u32 n = vui_key();
		TxtLoc l = txt_prev(&txt, txt_at(&txt, cur));
		for (;;) {
			u32 c = txt_chr(&txt, l);
			if (c == '\n') break;
			if (c == n) {
				cur = txt_ofs(&txt, l);
				break;
			}
			l = txt_prev(&txt, l);
		}
	} break;
	default:
		return 0;
	}
	if (count > 1 && last_cur != cur) {
		count--;
		goto loop;
	}
	count = 0;
	return 1;
}

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 (mode) {
		case 0:
			switch (c) {
			case 'q':
				goto brk;
			case 'z':
			case 'Z':
			case 0x13 /* ^S */:
				txt_save(&txt, path);
				//txt_load(&txt, "test.txt");
				if (c == 'Z') goto brk;
				break;
			case 'i':
				mode = 1;
				break;
			case 'a': {
				mode = 1;
				TxtLoc l = txt_at(&txt, cur);
				TxtLoc e = end_of_line(&txt, l);
				l = txt_before(l, e) ? txt_next(&txt, l) : e;
				cur = txt_ofs(&txt, l);
			} break;
			case 'I':
				mode = 1;
				cur = txt_ofs(&txt, start_of_line(&txt, txt_at(&txt, cur)));
				break;
			case 'A':
				mode = 1;
				cur = txt_ofs(&txt, end_of_line(&txt, txt_at(&txt, cur)));
				break;
			case 'o':
				mode = 1;
				cur = txt_ofs(&txt, end_of_line(&txt, txt_at(&txt, cur)));
				goto ins_newline;
			case 'O':
				mode = 1;
				cur = txt_ofs(&txt, txt_prev(&txt, start_of_line(&txt, txt_at(&txt, cur))));
				goto ins_newline;
			case 'd': {
				u32 before = cur;
				if (motion(vui_key())) {
					del_between(&txt, before, cur);
					if (before < cur) cur = before;
				}
			} break;
			case 'D': {
				u32 end = txt_ofs(&txt, end_of_line(&txt, txt_at(&txt, cur)));
				del_between(&txt, cur, end);
			} break;
			case 'C': {
				u32 end = txt_ofs(&txt, end_of_line(&txt, txt_at(&txt, cur)));
				del_between(&txt, cur, end);
				mode = 1;
			} break;
			case 'S': {
				TxtLoc l = start_of_line(&txt, txt_at(&txt, cur));
				u32 end = txt_ofs(&txt, end_of_line(&txt, l));
				del_between(&txt, txt_ofs(&txt, l), end);
				cur = txt_ofs(&txt, l);
				mode = 1;
			} break;
			case 'c': {
				u32 before = cur;
				if (motion(vui_key())) {
					del_between(&txt, before, cur);
					if (before < cur) cur = before;
				}
				mode = 1;
				break;
			}
			case 'x':
				txt_delete_c(&txt, txt_ofs(&txt, txt_next(&txt, txt_at(&txt, cur))));
				break;
			case 's':
				txt_delete_c(&txt, txt_ofs(&txt, txt_next(&txt, txt_at(&txt, cur))));
				mode = 1;
				break;
			case '1': case '2': case '3': case '4':
			case '5': case '6': case '7': case '8': case '9':
add_to_count:
				count = (count % 100000000) * 10 + c - '0';
				break;
			case '0':
				if (count) goto add_to_count;
				/* fallthrough */
			default:
				if (!motion(c)) {
					/* TODO: bell/flash? */
				}
				break;
			}
			break;
		case 1:
			switch (c) {
			case KEY_ESC:
				if (txt_after(txt_at(&txt, cur), start_of_line(&txt, txt_at(&txt, cur)))) cur--;
				mode = 0;
				break;
			case KEY_BKSP:
				cur = txt_delete_c(&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 '\r': {
ins_newline:;
				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;
			}
			break;
		}
		if (mode == 1) count = 0;
	}
brk:
	vui_fini();
	arena_free(&scratch);
	return 0;
}