#ifndef TXT_H
#define TXT_H

#include "dynarr.h"
#include "arena.h"
#include "str.h"

#define TXT_HIST_MAX 32

typedef enum : u8 {
	TXT_SRC,
	TXT_ADD
} TxtBufIdx;

typedef struct TxtPiece {
	TxtBufIdx buf;
	u32 ofs, n;
} TxtPiece;

typedef struct {
	char *s;
	u32 n, c;
} TxtBuf;

typedef struct {
	DYNARR(TxtPiece);
	int dirty;
} TxtPieceTbl;

typedef struct {
	struct Txt *t;
	u32 p, i;
} TxtLoc;

typedef struct {
	TxtPieceTbl v[TXT_HIST_MAX];
	TxtLoc cur[TXT_HIST_MAX];
	u32 i, n;
} TxtHist;

typedef struct Txt {
	TxtPieceTbl ptbl;
	TxtHist hist;
	TxtBuf buf[2];
	u32 len;
	int readonly;
} Txt;

/* text buffer manipulation */

TxtLoc txt_split_piece(TxtLoc l);
void txt_remove_piece(Txt *b, u32 pi);
void txt_insert_piece(Txt *b, u32 pi, TxtBufIdx buf, u32 ofs, u32 n);

void txt_load_empty(Txt *b);
int txt_load(Txt *b, const char *path);
int txt_save(Txt *b, const char *path);
void txt_free(Txt *b);

void txt_hist_push(Txt *t, TxtLoc cur);
int txt_hist_fwd(Txt *t, TxtLoc *cur);
int txt_hist_back(Txt *t, TxtLoc *cur);

Str txt_collect_range(TxtLoc lo, TxtLoc hi, Arena *a);
u32 txt_read_chunk(TxtLoc *lo, TxtLoc hi, char *buf, u32 sz);
Str txt_next_chunk(TxtLoc *l);
int txt_range_equal(TxtLoc lo, TxtLoc hi, Str s);

/* insertion & deletion */

TxtLoc txt_insert(TxtLoc l, const char *s, u32 n);
TxtLoc txt_delete(TxtLoc l, u32 n);
TxtLoc txt_delete_range(TxtLoc lo, TxtLoc hi);
TxtLoc txt_insert_c(TxtLoc l, u32 ch);
TxtLoc txt_delete_c(TxtLoc l);
u32 txt_range_len(TxtLoc lo, TxtLoc hi);

/* navigation */

int txt_valid_loc(TxtLoc l);
TxtLoc txt_at(Txt *b, u32 ofs);
u32 txt_ofs(TxtLoc l);
int txt_before(TxtLoc a, TxtLoc b);
int txt_after(TxtLoc a, TxtLoc b);
TxtLoc txt_start(Txt *t);
TxtLoc txt_end(Txt *t);

TxtLoc next_newline(TxtLoc l);
TxtLoc prev_newline(TxtLoc l);
TxtLoc start_of_line(TxtLoc l);
TxtLoc end_of_line(TxtLoc l);
TxtLoc prev_line(TxtLoc l);
TxtLoc next_line(TxtLoc l);
TxtLoc prev_line_start(TxtLoc l);
TxtLoc next_line_start(TxtLoc l);
TxtLoc at_col(TxtLoc l, u32 col);
u32 get_col(TxtLoc l);

/* reading */

u32 txt_chr(TxtLoc l);
u8 txt_byte(TxtLoc l);
u32 txt_chr_next(TxtLoc *l);

/* inline funcs */

static inline int at_start(TxtLoc l) {
	return l.p == 0 && l.i == 0;
}

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

static inline TxtLoc bnext(TxtLoc l) {
	TxtPiece *p = &l.t->ptbl.v[l.p];
	if (l.p + 1 < l.t->ptbl.n) {
		if (l.i + 1 < p->n) l.i++;
		else l.p++, l.i = 0;
	} else {
		l.i++;
		if (l.i > p->n) l.i = p->n;
	}
	return l;
}

static inline TxtLoc bprev(TxtLoc l) {
	if (l.i > 0) {
		return (TxtLoc) { l.t, l.p, l.i - 1 };
	} else if (l.p > 0 && l.t->ptbl.v[l.p - 1].n > 0) {
		return (TxtLoc) { l.t, l.p - 1, l.t->ptbl.v[l.p - 1].n - 1 };
	} else {
		return (TxtLoc) { l.t, 0, 0 };
	}
}

static inline TxtLoc cnext(TxtLoc l) {
	l = bnext(l);
	while ((txt_byte(l) & 0xc0) == 0x80) l = bnext(l);
	return l;
}

static inline TxtLoc cprev(TxtLoc l) {
	l = bprev(l);
	while ((txt_byte(l) & 0xc0) == 0x80) l = bprev(l);
	return l;
}

#endif