#include <stdint.h>
#include <stddef.h>

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

#include "wrmr.h"
#include "arena.h"
#include "dynarr.h"
#include "txt.h"
#include "utf8.h"
#include "str.h"

void txt_replace_piece(Txt *b, u32 pi, TxtBufIdx buf, u32 ofs, u32 n) {
	b->ptbl.v[pi] = (TxtPiece) { buf, ofs, n };
}

void txt_insert_piece(Txt *b, u32 pi, TxtBufIdx buf, u32 ofs, u32 n) {
	DA_FIT(&b->ptbl, b->ptbl.n + 1);
	if (pi < b->ptbl.n) {
		MOVE(&b->ptbl.v[pi+1], &b->ptbl.v[pi], b->ptbl.n - pi);
	}
	txt_replace_piece(b, pi, buf, ofs, n);
	b->ptbl.n++;
}

void txt_remove_piece(Txt *b, u32 pi) {
	if (pi + 1 < b->ptbl.n) {
		MOVE(&b->ptbl.v[pi], &b->ptbl.v[pi+1], b->ptbl.n - (pi + 1));
	}
	b->ptbl.n--;
}

/* ensures that the returned TxtLoc is at the end of its respective piece,
 * one past the final character.  note that this is an invalid position for
 * normal navigation, so it must be moved back into place with resolve_loc()
 * or txt_post_edit().
 */
TxtLoc txt_split_piece(TxtLoc l) {
	TxtPiece *p = &l.t->ptbl.v[l.p];
	if (l.i < p->n) {
		if (l.i == 0 && l.p > 0) {
			l.p--;
			l.i = l.t->ptbl.v[l.p].n;
		} else {
			txt_insert_piece(l.t, l.p + 1, p->buf, p->ofs + l.i, p->n - l.i);
			l.t->ptbl.v[l.p].n = l.i;
		}
	}
	ASSERT(l.p < l.t->ptbl.n);
	ASSERT(l.i == l.t->ptbl.v[l.p].n);
	return l;
}

TxtLoc txt_add_piece(TxtLoc l) {
	l = txt_split_piece(l);
	TxtPiece *p = &l.t->ptbl.v[l.p];
	if (p->buf != TXT_ADD || p->ofs + p->n != l.t->buf[TXT_ADD].n) {
		if (l.i > 0) {
			txt_insert_piece(l.t, l.p + 1, TXT_ADD, l.t->buf[TXT_ADD].n, 0);
			l.p++;
			l.i = 0;
		} else {
			txt_replace_piece(l.t, l.p, TXT_ADD, l.t->buf[TXT_ADD].n, 0);
		}
	}
	return l;
}

static void txt_buf_fit(Txt *b, TxtBufIdx bi, u32 sz) {
	TxtBuf *buf = &b->buf[bi];
	if (sz > buf->c) {
		buf->c = stdc_bit_ceil(sz);
		buf->s = realloc(buf->s, buf->c);
		if (!buf->s) FAIL_WITH_MSG("realloc failure");
	}
}

static void txt_buf_append(Txt *b, TxtBufIdx bi, const char *s, u32 n) {
	TxtBuf *buf = &b->buf[bi];
	txt_buf_fit(b, bi, buf->n + n);
	memcpy(&buf->s[buf->n], s, n);
	buf->n += n;
}

static isize txt_buf_dedup(Txt *b, TxtBufIdx bi, const char *s, u32 n) {
	TxtBuf *buf = &b->buf[bi];
	if (buf->n >= n && buf->s && !memcmp(buf->s + (buf->n - n), s, n)) {
		return buf->n - n;
	} else {
		return -1;
	}
}

static int txt_are_pieces_adjacent(Txt *t, u32 a, u32 b) {
	TxtPiece *pa = &t->ptbl.v[a];
	TxtPiece *pb = &t->ptbl.v[b];
	return pa->buf == pb->buf && pa->ofs + pa->n == pb->ofs;
}

static inline TxtLoc resolve_loc(TxtLoc l) {
	while (l.p + 1 < l.t->ptbl.n && l.i == l.t->ptbl.v[l.p].n) {
		l.p++;
		l.i = 0;
	}
	ASSERT(txt_valid_loc(l));
	return l;
}

static TxtLoc txt_post_edit(TxtLoc l) {
	l = resolve_loc(l);
loop:
	if (l.p > 0 && txt_are_pieces_adjacent(l.t, l.p - 1, l.p)) {
		l.i = l.t->ptbl.v[l.p - 1].n;
		l.t->ptbl.v[l.p - 1].n += l.t->ptbl.v[l.p].n;
		txt_remove_piece(l.t, l.p);
		l.p--;
		ASSERT(txt_valid_loc(l));
		goto loop;
	}
	if (l.p + 1 < l.t->ptbl.n && txt_are_pieces_adjacent(l.t, l.p, l.p + 1)) {
		l.t->ptbl.v[l.p].n += l.t->ptbl.v[l.p + 1].n;
		txt_remove_piece(l.t, l.p + 1);
		ASSERT(txt_valid_loc(l));
		goto loop;
	}
	ASSERT(txt_valid_loc(l));
	l.t->ptbl.dirty = 1;
	return resolve_loc(l);
}

TxtLoc txt_insert(TxtLoc l, const char *s, u32 n) {
	if (l.t->readonly) return l;
	l = txt_add_piece(l);
	TxtPiece *p = &l.t->ptbl.v[l.p];
	isize ext = txt_buf_dedup(l.t, p->buf, s, n);
	if (p->n > 0 || ext == -1) {
		txt_buf_append(l.t, p->buf, s, n);
	} else {
		p->ofs = ext;
	}
	p->n += n;
	l.t->len += n;
	l.i = p->n;
	return txt_post_edit(l);
}

TxtLoc txt_delete(TxtLoc l, u32 n) {
	if (l.t->readonly) return l;
	l = txt_split_piece(l);
	while (n > 0) {
		TxtPiece *p = &l.t->ptbl.v[l.p];
		u32 sz = p->n > n ? n : p->n;
		p->n -= sz;
		l.i -= sz;
		n -= sz;
		if (!p->n && l.t->ptbl.n > 1) txt_remove_piece(l.t, l.p);
		if (l.p == 0) break;
		if (l.i == 0) {
			l.p--;
			l.i = l.t->ptbl.v[l.p].n;
		}
	}
	return txt_post_edit(l);
}

TxtLoc txt_insert_c(TxtLoc l, u32 ch) {
	char buf[6];
	u32 n = utf8_encode_len(&ch, 1);
	utf8_encode(buf, &ch, 1);
	return txt_insert(l, buf, n);
}

u32 txt_range_len(TxtLoc lo, TxtLoc hi) {
	u32 n = 0;
	while (lo.p < hi.p) {
		n += lo.t->ptbl.v[lo.p].n - lo.i;
		lo.p++;
		lo.i = 0;
	}
	n += hi.i - lo.i;
	return n;
}

TxtLoc txt_delete_range(TxtLoc lo, TxtLoc hi) {
	/* TODO: figure out nr. of chars, then delete all at once */
	if (txt_before(hi, lo)) {
		TxtLoc t = lo;
		lo = hi;
		hi = t;
	}
	return txt_delete(hi, txt_range_len(lo, hi));
}

TxtLoc txt_delete_c(TxtLoc l) {
	if (l.t->readonly) return l;
	while (!at_start(l) && (txt_byte(bprev(l)) & 0xc0) == 0x80)
		l = txt_delete(l, 1);
	l = txt_delete(l, 1);
	return l;
}

int txt_load(Txt *b, const char *path) {
	struct stat sb;
	memset(b, 0, sizeof(Txt));
	int fd = open(path, O_RDONLY);
	if (fd == -1) goto empty_file;
	if (fstat(fd, &sb)) {
		close(fd);
		return -1;
	}
	if (!sb.st_size) {
empty_file:
		txt_buf_fit(b, TXT_SRC, 8192);
		goto done;
	}
	void *m = mmap(0, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
	if (m == MAP_FAILED) {
		close(fd);
		return -1;
	}
	txt_buf_fit(b, TXT_SRC, sb.st_size);
	memcpy(b->buf[TXT_SRC].s, m, sb.st_size);
	munmap(m, sb.st_size);
	b->buf[TXT_SRC].n = sb.st_size;
	close(fd);
done:
	b->buf[TXT_ADD].n = 0;
	b->len = b->buf[TXT_SRC].n;
	txt_insert_piece(b, 0, TXT_SRC, 0, b->len);
	return 0;
}

void txt_load_empty(Txt *b) {
	memset(b, 0, sizeof(Txt));
	txt_buf_fit(b, TXT_SRC, 32);
	txt_buf_fit(b, TXT_ADD, 8192);
	txt_insert_piece(b, 0, TXT_ADD, 0, b->len);
}

static inline int txt_hist_unchanged(Txt *t) {
	if (t->hist.n < 1) return 0;
	TxtHistNode *pt = &t->hist.v[t->hist.i];
	if (t->ptbl.n != pt->n) return 0;
	if (memcmp(pt->v, t->ptbl.v, sizeof(TxtPiece) * pt->n)) return 0;
	return 1;
}

int txt_save(Txt *t, const char *path) {
	FILE *f = fopen(path, "wb");
	if (!f) return -1;
	for (u32 i = 0; i < t->ptbl.n; i++) {
		TxtPiece *p = &t->ptbl.v[i];
		TxtBuf *b = &t->buf[p->buf];
		fwrite(b->s + p->ofs, 1, p->n, f);
	}
	int e = ferror(f);
	fclose(f);
	t->ptbl.dirty = 0;
	for (u32 i = 0; i < t->hist.n; i++) t->hist.v[i].dirty = 1;
	if (txt_hist_unchanged(t)) t->hist.v[t->hist.i].dirty = 0;
	return e ? -1 : 0;
}

void txt_free(Txt *t) {
	for (u32 i = 0; i < COUNTOF(t->buf); i++)
		free(t->buf[i].s);
	for (u32 i = 0; i < TXT_HIST_MAX; i++)
		free(t->hist.v[i].v);
	free(t->ptbl.v);
}

void txt_hist_push(Txt *t, TxtLoc cur) {
	if (txt_hist_unchanged(t)) {
		t->hist.v[t->hist.i].cur = cur;
		return;
	}
	if (t->hist.i + 1 < t->hist.n) t->hist.n = t->hist.i + 1;
	if (t->hist.n) t->hist.i++;
	if (t->hist.i == TXT_HIST_MAX) {
		free(t->hist.v[0].v);
		MOVE(&t->hist.v[0], &t->hist.v[1], TXT_HIST_MAX - 1);
		memset(&t->hist.v[TXT_HIST_MAX - 1], 0, sizeof(*t->hist.v));
		t->hist.i--;
		t->hist.n--;
	}
	DA_FIT(&t->hist.v[t->hist.i], t->ptbl.n);
	memcpy(t->hist.v[t->hist.i].v, t->ptbl.v, sizeof(TxtPiece) * t->ptbl.n);
	t->hist.v[t->hist.i].n = t->ptbl.n;
	t->hist.v[t->hist.i].dirty = t->ptbl.dirty;
	t->hist.v[t->hist.i].cur = cur;
	t->hist.n++;
	ASSERT(t->hist.n == t->hist.i + 1);
}

int txt_hist_set(Txt *t, TxtLoc *cur) {
	t->ptbl.n = t->hist.v[t->hist.i].n;
	DA_FIT(&t->ptbl, t->ptbl.n);
	memcpy(t->ptbl.v, t->hist.v[t->hist.i].v, sizeof(TxtPiece) * t->ptbl.n);
	t->ptbl.dirty = t->hist.v[t->hist.i].dirty;
	*cur = t->hist.v[t->hist.i].cur;
	return 1;
}

int txt_hist_fwd(Txt *t, TxtLoc *cur) {
	if (t->hist.i + 1 >= t->hist.n) return 0;
	t->hist.i++;
	return txt_hist_set(t, cur);
}

int txt_hist_back(Txt *t, TxtLoc *cur) {
	if (t->hist.i == 0) return 0;
	t->hist.i--;
	return txt_hist_set(t, cur);
}

Str txt_collect_range(TxtLoc lo, TxtLoc hi, Arena *a) {
	DYNARR(char) buf = { 0 };
	while (lo.p < hi.p) {
		TxtPiece *p = &lo.t->ptbl.v[lo.p];
		DA_APUSH_MULT(&buf, a, lo.t->buf[p->buf].s + p->ofs + lo.i, p->n - lo.i);
		lo.p++;
		lo.i = 0;
	}
	ASSERT(lo.p == hi.p);
	if (hi.i > lo.i) {
		TxtPiece *p = &lo.t->ptbl.v[lo.p];
		DA_AGROW(&buf, a, hi.i - lo.i);
		memcpy((&buf)->v + (&buf)->n, lo.t->buf[p->buf].s + p->ofs + lo.i, DA_ELEM(&buf, hi.i - lo.i));
		(&buf)->n += (hi.i - lo.i);
		//DA_APUSH_MULT(&buf, a, lo.t->buf[p->buf].s + p->ofs + lo.i, hi.i - lo.i);
	}
	return (Str) { buf.v, buf.n };
}

u32 txt_read_chunk(TxtLoc *lo, TxtLoc hi, char *buf, u32 sz) {
	u32 n = 0;
	TxtLoc l = *lo;
	while (n < sz && l.p < hi.p) {
		TxtPiece *p = &l.t->ptbl.v[l.p];
		u32 copy_n = p->n - l.i;
		if (copy_n > sz - n) copy_n = sz - n;
		memcpy(buf + n, l.t->buf[p->buf].s + p->ofs + l.i, copy_n);
		n += copy_n;
		l.i += copy_n;
		if (l.i >= p->n) {
			l.p++;
			l.i = 0;
		}
	}
	if (n < sz && hi.i > l.i) {
		TxtPiece *p = &l.t->ptbl.v[l.p];
		u32 copy_n = hi.i - l.i;
		if (copy_n > sz - n) copy_n = sz - n;
		memcpy(buf + n, l.t->buf[p->buf].s + p->ofs + l.i, copy_n);
	}
	*lo = l;
	return n;
}

Str txt_next_chunk(TxtLoc *l) {
	TxtPiece *p = &l->t->ptbl.v[l->p];
	Str s = { l->t->buf[p->buf].s + p->ofs + l->i, p->n - l->i };
	if (l->p + 1 < l->t->ptbl.n) {
		l->p++;
		l->i = 0;
	} else {
		l->i = p->n;
	}
	return s;
}

Str txt_prev_chunk(TxtLoc *l) {
	while (!l->i && l->p > 0) {
		l->p--;
		l->i = l->t->ptbl.v[l->p].n;
	}
	TxtPiece *p = &l->t->ptbl.v[l->p];
	Str s = { l->t->buf[p->buf].s + p->ofs, l->i };
	l->i = 0;
	return s;
}

int txt_range_equal(TxtLoc lo, TxtLoc hi, Str cmp) {
	u32 i = 0;
	while (txt_before(lo, hi)) {
		Str s = txt_next_chunk(&lo);
		u32 n = cmp.n - i;
		if (s.n < n) n = s.n;
		if (s.n > 0 && memcmp(s.s, cmp.s + i, n))
			return 0;
		i += s.n;
	}
	return 1;
}

/* navigation */

int txt_valid_loc(TxtLoc l) {
	return l.p < l.t->ptbl.n
	    && (l.i < l.t->ptbl.v[l.p].n
		|| (l.p + 1 == l.t->ptbl.n
			&& l.i <= l.t->ptbl.v[l.p].n));
}

TxtLoc txt_at(Txt *b, u32 ofs) {
	for (u32 i = 0; i < b->ptbl.n; i++) {
		if (ofs < b->ptbl.v[i].n) {
			return (TxtLoc) { b, i, ofs };
		}
		ofs -= b->ptbl.v[i].n;
	}
	return (TxtLoc) { b, b->ptbl.n - 1, b->ptbl.v[b->ptbl.n - 1].n };
}

u32 txt_ofs(TxtLoc l) {
	u32 r = 0;
	for (u32 i = 0; i < l.p; i++) {
		r += l.t->ptbl.v[i].n;
	}
	return r + l.i;
}

int txt_before(TxtLoc a, TxtLoc b) {
	ASSERT(txt_valid_loc(a));
	ASSERT(txt_valid_loc(b));
	return a.p < b.p || (a.p == b.p && a.i < b.i);
}

int txt_after(TxtLoc a, TxtLoc b) {
	ASSERT(txt_valid_loc(a));
	ASSERT(txt_valid_loc(b));
	return a.p > b.p || (a.p == b.p && a.i > b.i);
}

TxtLoc txt_start(Txt *t) {
	return (TxtLoc) { t, 0, 0 };
}

TxtLoc txt_end(Txt *t) {
	return (TxtLoc) { t, t->ptbl.n-1, t->ptbl.v[t->ptbl.n-1].n };
}

/* TODO: make these use memchr() or equivalent */

TxtLoc next_newline(TxtLoc l) {
	do l = cnext(l);
	while (!at_end(l) && txt_byte(l) != '\n');
	return l;
}

TxtLoc prev_newline(TxtLoc l) {
	do l = cprev(l);
	while (!at_start(l) && txt_byte(l) != '\n');
	return l;
}

TxtLoc start_of_line(TxtLoc l) {
	if (at_start(l)) return l;
	l = prev_newline(l);
	if (txt_byte(l) == '\n') l = cnext(l);
	return l;
}

TxtLoc end_of_line(TxtLoc l) {
	TxtLoc start = start_of_line(l);
	return txt_byte(start) == '\n' ? start : next_newline(start);
}

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

TxtLoc at_col(TxtLoc l, u32 col) {
	l = start_of_line(l);
	while (col-- && txt_byte(l) != '\n') l = cnext(l);
	return l;
}

TxtLoc next_line_start(TxtLoc l) {
	if (txt_byte(l) == '\n') return cnext(l);
	return cnext(next_newline(l));
}

TxtLoc prev_line_start(TxtLoc l) {
	return start_of_line(prev_newline(l));
}

TxtLoc prev_line(TxtLoc l) {
	return at_col(prev_line_start(l), get_col(l));
}

TxtLoc next_line(TxtLoc l) {
	return at_col(next_line_start(l), get_col(l));
}

/* reading chars */

u32 txt_chr(TxtLoc l) {
	TxtPiece *p = &l.t->ptbl.v[l.p];
	TxtBuf *b = &l.t->buf[p->buf];
	return utf8_decode_at(b->s, p->ofs + l.i, p->ofs + p->n);
}

u8 txt_byte(TxtLoc l) {
	TxtPiece *p = &l.t->ptbl.v[l.p];
	TxtBuf *b = &l.t->buf[p->buf];
	if (l.i >= p->n) return 0;
	return b->s[p->ofs + l.i];
}

u32 txt_chr_next(TxtLoc *l) {
	if (at_end(*l)) return 0;
	u32 c = txt_chr(*l);
	u32 n = UTF8_CP_LEN(c);
	for (u32 i = 0; i < n; i++) *l = bnext(*l);
	return c;
}