#include "dat.h"
#include "fn.h"

static Im im;
static void *activeowner;
static int activecap;
static Caret caret;
static int candidatechosen;
static Drawcmd lastdraw;
static Emit transjp(Im*, Rune);
static void backjp(Im*);

typedef struct Search Search;
struct Search
{
	int	lang;
	Str	raw;
	Str	text;
};
static Search search;

Lang langs[] = {
	{LangEN,    nil,       nil,      nil,      nil,     nil, nil},
	{LangJP,    "hira",    "kanji",  transjp,  backjp,  nil, nil},
	{LangJPK,   "kata",    nil,      transjp,  backjp,  nil, nil},
	{LangKO,    nil,       nil,      transko,  backko,  nil, nil},
	{LangHANJA, nil,       "hanja",  nil,      nil,     nil, nil},
	{LangEMOJI, nil,       "emoji",  nil,      nil,     nil, nil},
	{LangVI,    "telex",   nil,      transvi,  backvi,  nil, nil},
};
int nlang = nelem(langs);

/* Trie match kind for key; on an exact match out holds the value. */
static int
mapmatch(Trie *t, Str *key, Str *out)
{
	char *v;
	int match, vlen;

	sclear(out);
	if(key->n == 0)
		return TrieMiss;
	match = trielookup(t, key, &v, &vlen);
	if(match == TrieExact && !sinit(out, v, vlen))
		return TrieMiss;
	return match;
}

int
mapget(Trie *t, Str *key, Str *out)
{
	return mapmatch(t, key, out) == TrieExact;
}

static void
clearkouho(void)
{
	im.nkouho = 0;
	im.sel = -1;
	candidatechosen = 0;
}

static void
selectfirst(void)
{
	im.sel = im.nkouho > 0 ? 0 : -1;
}

static int
pagefirst(void)
{
	if(im.sel < 0)
		return 0;
	return im.sel / Maxdisp * Maxdisp;
}

static int
movedelta(u32int ks)
{
	switch(ks){
	case Kup:	return -1;
	case Kdown:	return 1;
	case Kpgup:	return -Maxdisp;
	case Kpgdown:	return Maxdisp;
	}
	return 0;
}

static void
movekouho(int delta)
{
	if(im.sel < 0)
		im.sel = 0;
	else
		im.sel += delta;
	if(im.sel < 0)
		im.sel = 0;
	if(im.sel >= im.nkouho)
		im.sel = im.nkouho - 1;
	candidatechosen = 1;
}

static int
numberedkouho(u32int ks, u32int mod)
{
	int n;

	if(mod != 0 || ks < '1' || ks > '9')
		return -1;
	n = pagefirst() + ks - '1';
	if(n >= im.nkouho)
		return -1;
	return n;
}

static int
isjp(Im *p)
{
	return p->l->lang == LangJP || p->l->lang == LangJPK;
}

/*
 * Japanese keeps completed kana in pre and an ambiguous romaji syllable in
 * raw.  A mapped raw suffix is part of the reading even while it remains
 * pending (notably n, which may still grow into nya).  Returns whether
 * the reading is complete.
 */
static int
jpreading(Trie *map, Str *pre, Str *raw, Str *s)
{
	Str mapped;

	*s = *pre;
	if(raw->n == 0)
		return 1;
	if(mapget(map, raw, &mapped)){
		sappend(s, &mapped);
		return 1;
	}
	sappend(s, raw);
	return 0;
}

static int
haspre(Im *p)
{
	return p->pre.n != 0 || p->raw.n != 0;
}

/* The preedit as clients see it: Telex keys read back through the map. */
void
impre(Im *p, Str *s)
{
	if(isjp(p))
		jpreading(p->l->map, &p->pre, &p->raw, s);
	else if(!mapget(p->l->map, &p->pre, s))
		*s = p->pre;
}

static void
snapshot(Drawcmd *dc)
{
	Str pre;
	int i, first, n;

	memset(dc, 0, sizeof *dc);
	if(search.lang)
		pre = search.text;
	else
		impre(&im, &pre);
	if(!(activecap & Cclientpreedit))
		dc->pre = pre;
	first = pagefirst();
	n = im.nkouho - first;
	if(n > Maxdisp) n = Maxdisp;
	dc->nkouho = n;
	dc->sel = im.sel >= 0 ? im.sel - first : -1;
	dc->first = first;
	dc->total = im.nkouho;
	dc->caret = caret;
	for(i = 0; i < n; i++)
		dc->kouho[i] = im.kouho[first + i];
}

static int
careteq(Caret *a, Caret *b)
{
	return a->valid == b->valid && a->x == b->x && a->y == b->y &&
		a->h == b->h;
}

static int
shown(Drawcmd *dc)
{
	return dc->pre.n != 0 || dc->nkouho != 0;
}

static int
samedraw(Drawcmd *a, Drawcmd *b)
{
	int i;

	if(!shown(a) && !shown(b))
		return 1;
	if(a->nkouho != b->nkouho || a->sel != b->sel ||
	   a->first != b->first || a->total != b->total ||
	   scmp(&a->pre, &b->pre) != 0 || !careteq(&a->caret, &b->caret))
		return 0;
	for(i = 0; i < a->nkouho; i++)
		if(scmp(&a->kouho[i], &b->kouho[i]) != 0)
			return 0;
	return 1;
}

/* Sends the popup a new picture only when it would look different. */
static void
redraw(void)
{
	Drawcmd dc, junk;

	snapshot(&dc);
	if(samedraw(&dc, &lastdraw))
		return;
	lastdraw = dc;
	/* imthread is the sole producer; keep only the newest pending draw. */
	while(channbrecv(drawc, &junk) > 0)
		;
	channbsend(drawc, &dc);
}

static void
reset(void)
{
	sclear(&im.pre);
	sclear(&im.raw);
	search.lang = 0;
	sclear(&search.raw);
	sclear(&search.text);
	memset(&caret, 0, sizeof caret);
	clearkouho();
}

/* Kanji candidates for a complete reading. */
static void
dictqjp(void)
{
	Str reading;

	clearkouho();
	if(!jpreading(im.l->map, &im.pre, &im.raw, &reading) || reading.n == 0)
		return;
	im.nkouho = dictlookup(im.l, &reading, im.kouho, Maxkouho);
	selectfirst();
}

static int
setlang(int c)
{
	Lang *l;

	l = getlang(c);
	if(l == nil)
		return 0;
	im.l = l;
	return 1;
}

static void
commitim(Im *p, Str *com)
{
	Str val;

	if(isjp(p))
		jpreading(p->l->map, &p->pre, &p->raw, &val);
	else if(!mapget(p->l->map, &p->pre, &val))
		val = p->pre;
	sappend(com, &val);
	sclear(&p->pre);
	sclear(&p->raw);
}

static void
commit(Str *com)
{
	commitim(&im, com);
}

static void
backjp(Im *p)
{
	if(p->raw.n != 0)
		spopr(&p->raw);
	else
		spopr(&p->pre);
}

static int
issmalltsu(Str *s)
{
	return s->n == 1 && (s->r[0] == L'っ' || s->r[0] == L'ッ');
}

static void
keeptail(Str *s)
{
	int i;

	for(i = 1; i < s->n; i++)
		s->r[i-1] = s->r[i];
	if(s->n > 0)
		s->n--;
}

static Emit
transjp(Im *p, Rune c)
{
	Emit e;
	Str key, mapped;

	memset(&e, 0, sizeof e);
	e.eat = 1;
	e.next = p->pre;
	e.raw = p->raw;
	if(c == '\'' && e.raw.n == 1 && e.raw.r[0] == 'n'){
		if(mapget(p->l->map, &e.raw, &mapped))
			sappend(&e.next, &mapped);
		sclear(&e.raw);
		return e;
	}
	key = e.raw;
	sputr(&key, c);
	if(mapmatch(p->l->map, &key, &mapped) != TrieMiss){
		e.raw = key;
		if(issmalltsu(&mapped)){
			sappend(&e.next, &mapped);
			keeptail(&e.raw);
		}
		return e;
	}
	if(e.raw.n != 0 && mapget(p->l->map, &e.raw, &mapped)){
		sappend(&e.next, &mapped);
		sclear(&e.raw);
		sclear(&key);
		sputr(&key, c);
		if(mapmatch(p->l->map, &key, &mapped) != TrieMiss){
			e.raw = key;
			return e;
		}
	}
	/* The key starts no syllable: flush the reading and pass it on. */
	jpreading(p->l->map, &e.next, &e.raw, &e.s);
	sclear(&e.next);
	sclear(&e.raw);
	e.eat = 0;
	return e;
}

static int
dotrans(Rune c, Str *com)
{
	Emit e;

	e = im.l->trans(&im, c);
	sappend(com, &e.s);
	im.pre = e.next;
	im.raw = e.raw;
	if(e.eat && isjp(&im))
		dictqjp();
	else
		clearkouho();
	return e.eat;
}

Lang*
getlang(int lang)
{
	int i;

	for(i = 0; i < nelem(langs); i++)
		if(langs[i].lang == lang)
			return &langs[i];
	return nil;
}

/*
 * The pending text is the key sequence itself while it is a prefix of some
 * map entry; the map value is what gets shown and committed.
 */
Emit
transmap(Im *p, Rune c)
{
	Emit e = {0};
	Str key, mapped;
	Trie *t;

	t = p->l->map;
	key = p->pre;
	sputr(&key, c);
	if(mapmatch(t, &key, &mapped) != TrieMiss){
		e.eat = 1;
		e.next = key;
		return e;
	}
	if(!mapget(t, &p->pre, &e.s))
		e.s = p->pre;
	sclear(&key);
	sputr(&key, c);
	if(mapmatch(t, &key, &mapped) == TrieMiss)
		return e;
	e.eat = 1;
	sputr(&e.next, c);
	return e;
}

static Rune
ctrlkey(Rune c)
{
	if(c >= 'A' && c <= 'Z')
		c += 'a' - 'A';
	if(c >= 'a' && c <= 'z')
		return c - 'a' + 1;
	return c;
}

static Rune
kokey(Rune c, u32int mod)
{
	if(c >= 'A' && c <= 'Z')
		c += 'a' - 'A';
	if((mod & Mshift) && c >= 'a' && c <= 'z')
		c -= 'a' - 'A';
	return c;
}

static int
ismodkey(u32int ks)
{
	return ks >= Kmodfirst && ks <= Kmodlast;
}

/* Modifier presses and unmapped keys never engage the engine. */
int
keymeaningful(u32int ks)
{
	return ks != 0 && !ismodkey(ks);
}

static void
foldascii(Str *s)
{
	int i;

	for(i = 0; i < s->n; i++)
		if(s->r[i] >= 'A' && s->r[i] <= 'Z')
			s->r[i] += 'a' - 'A';
}

/* What typing raw in language l would produce, composition included. */
void
transstr(Lang *l, Str *raw, Str *out)
{
	Im q;
	Emit e;
	int i;

	sclear(out);
	if(l->trans == nil){
		*out = *raw;
		return;
	}
	memset(&q, 0, sizeof q);
	q.l = l;
	for(i = 0; i < raw->n; i++){
		e = l->trans(&q, raw->r[i]);
		sappend(out, &e.s);
		q.pre = e.next;
		q.raw = e.raw;
		if(!e.eat)
			sputr(out, raw->r[i]);
	}
	commitim(&q, out);
}

static void
addkouho(Str *s)
{
	int i;

	for(i = 0; i < im.nkouho; i++)
		if(scmp(&im.kouho[i], s) == 0)
			return;
	if(im.nkouho < Maxkouho)
		im.kouho[im.nkouho++] = *s;
}

/* The typed keys and their transliteration are both emoji queries. */
static void
emojiquery(void)
{
	Str kouho[Maxkouho], raw, local;
	int i, n, rawhit, localhit;

	raw = search.raw;
	foldascii(&raw);
	transstr(im.l, &search.raw, &local);
	foldascii(&local);
	clearkouho();
	n = dictlookup(getlang(LangEMOJI), &raw, kouho, Maxkouho);
	rawhit = n != 0;
	for(i = 0; i < n; i++)
		addkouho(&kouho[i]);
	localhit = 0;
	if(scmp(&raw, &local) != 0){
		n = dictlookup(getlang(LangEMOJI), &local, kouho, Maxkouho);
		localhit = n != 0;
		for(i = 0; i < n; i++)
			addkouho(&kouho[i]);
	}
	search.text = rawhit || !localhit ? raw : local;
	selectfirst();
}

static void
hanjaquery(void)
{
	Str key;

	transstr(im.l, &search.raw, &key);
	search.text = key;
	clearkouho();
	im.nkouho = dictlookup(getlang(LangHANJA), &key, im.kouho, Maxkouho);
	selectfirst();
}

static void
searchquery(void)
{
	if(search.lang == LangEMOJI)
		emojiquery();
	else if(search.lang == LangHANJA)
		hanjaquery();
}

static int
searchlang(Rune c)
{
	return c == LangEMOJI || c == LangHANJA ? c : 0;
}

static void
endsearch(void)
{
	search.lang = 0;
	sclear(&search.raw);
	sclear(&search.text);
	clearkouho();
}

static void
commitsearch(Str *com)
{
	sappend(com, &search.text);
	endsearch();
}

/* A search commits whatever is pending and takes over the keys. */
static void
startsearch(int lang, Str *com)
{
	commit(com);
	commitsearch(com);
	search.lang = lang;
}

/*
 * Whatever is pending becomes committed text, a moved-to candidate
 * first: Enter does this, and so do a reset and a lost focus.
 */
static void
flush(Str *com)
{
	if(search.lang)
		commitsearch(com);
	else if(candidatechosen && im.sel >= 0 && im.sel < im.nkouho)
		sappend(com, &im.kouho[im.sel]);
	else
		commit(com);
	reset();
}

static void
picksearch(int n, Str *com)
{
	sappend(com, &im.kouho[n]);
	endsearch();
}

static int
searchkey(u32int ks, u32int mod, Str *com)
{
	int n;
	Rune c;

	n = movedelta(ks);
	if(n != 0){
		if(im.nkouho == 0)
			return 1;
		movekouho(n);
		return 1;
	}
	n = numberedkouho(ks, mod);
	if(n >= 0){
		picksearch(n, com);
		return 1;
	}
	if(ks == Ktab){
		if(im.nkouho == 0)
			return 1;
		if(mod & Mshift){
			if(im.sel <= 0)
				im.sel = im.nkouho - 1;
			else
				im.sel--;
		}else if(im.sel >= im.nkouho - 1)
			im.sel = 0;
		else
			im.sel++;
		return 1;
	}
	if(ks == Kret){
		if(im.nkouho > 0)
			picksearch(max(im.sel, 0), com);
		else
			commitsearch(com);
		return 1;
	}
	if(ks == Kback){
		if(search.raw.n == 0){
			endsearch();
			return 0;
		}
		spopr(&search.raw);
		searchquery();
		return 1;
	}
	if(ks == Kesc){
		endsearch();
		return 1;
	}
	if(ks >= Kspec || (ks < ' ' && !(mod & Mctrl)) ||
	   (mod & (Malt|Msuper))){
		commitsearch(com);
		return 0;
	}
	if(mod & Mctrl){
		c = ctrlkey(ks);
		n = searchlang(c);
		if(n != 0 && n != search.lang){
			startsearch(n, com);
			return 1;
		}
		commitsearch(com);
		return n != 0 || setlang(c);
	}
	if(search.raw.n >= Maxrunes){
		commitsearch(com);
		return 0;
	}
	sputr(&search.raw, ks);
	searchquery();
	return 1;
}

static int
transition(u32int ks, u32int mod, Str *com)
{
	int n;
	Rune c;

	if(ismodkey(ks))
		return 0;
	if(im.l->lang == LangKO)
		ks = kokey(ks, mod);
	if(search.lang)
		return searchkey(ks, mod, com);
	n = movedelta(ks);
	if(n != 0 && im.nkouho != 0){
		movekouho(n);
		return 1;
	}
	n = numberedkouho(ks, mod);
	if(n >= 0){
		sappend(com, &im.kouho[n]);
		reset();
		return 1;
	}
	if(ks == Ktab || ks == Kret){
		if(!haspre(&im))
			return 0;
		flush(com);
		/* Japanese confirms with the key; Korean and Telex let it on. */
		return isjp(&im);
	}
	if(ks == Kback){
		if(!haspre(&im))
			return 0;
		im.l->back(&im);
		if(!haspre(&im)){
			reset();
			return 1;
		}
		if(isjp(&im))
			dictqjp();
		else
			clearkouho();
		return 1;
	}
	if(ks == Kesc){
		if(!haspre(&im))
			return 0;
		reset();
		return 1;
	}
	if(ks >= Kspec || (mod & (Malt|Msuper))){
		commit(com);
		reset();
		return 0;
	}
	if(mod & Mctrl){
		c = ctrlkey(ks);
		n = searchlang(c);
		if(n != 0){
			startsearch(n, com);
			return 1;
		}
		commit(com);
		reset();
		return setlang(c);
	}
	if(ks == '0' && im.nkouho > 0){
		commit(com);
		reset();
		return 1;
	}
	if(ks > 0x7f || ks == ' '){
		if(!haspre(&im))
			return 0;
		commit(com);
		reset();
		if(com->n >= Maxrunes)
			return 0;
		sputr(com, ks);
		return 1;
	}
	if(im.l->trans == nil)
		return 0;
	if(im.pre.n >= Maxrunes ||
	   (isjp(&im) && im.pre.n + im.raw.n >= Maxrunes)){
		/* A full reading commits; a pending romaji syllable stays. */
		if(isjp(&im))
			sappend(com, &im.pre);
		else
			commit(com);
		sclear(&im.pre);
		clearkouho();
	}
	return dotrans(ks, com);
}

static void
init(void)
{
	memset(&im, 0, sizeof(im));
	im.l = getlang(LangEN);
	im.sel = -1;
	memset(&search, 0, sizeof search);
	memset(&caret, 0, sizeof caret);
	activeowner = nil;
	activecap = 0;
	candidatechosen = 0;
	memset(&lastdraw, 0, sizeof lastdraw);
}

/*
 * The engine belongs to whichever context last typed a real key; only
 * the owner's requests change state.  A reset or release hands the
 * owner its pending text back as commit.  Every request ends in
 * redraw(), which sends the popup a picture only if something visible
 * changed.
 */
static void
imhandlekey(Keyreq *kr)
{
	Keyres res;

	sclear(&res.commit);
	sclear(&res.preedit);
	res.eaten = 1;
	switch(kr->op){
	case Keyrelease:
		if(kr->owner == activeowner){
			flush(&res.commit);
			activeowner = nil;
			activecap = 0;
		}
		break;
	case Keyreset:
		if(kr->owner == activeowner)
			flush(&res.commit);
		break;
	case Keycaret:
		if(kr->owner == activeowner)
			caret = kr->caret;
		break;
	case Keycap:
		res.eaten = activeowner != nil && kr->owner == activeowner;
		if(res.eaten)
			activecap = kr->cap & Cclientpreedit;
		break;
	case Keypress:
		res.eaten = 0;
		if(activeowner != nil && kr->owner == activeowner)
			activecap = kr->cap & Cclientpreedit;
		if(keymeaningful(kr->ks)){
			if(kr->owner != activeowner){
				reset();
				activeowner = kr->owner;
				activecap = kr->cap & Cclientpreedit;
				caret = kr->caret;
			}else if(kr->caret.valid)
				caret = kr->caret;
			res.eaten = transition(kr->ks, kr->mod, &res.commit);
		}
		break;
	}
	redraw();
	if(kr->owner == activeowner){
		if(search.lang)
			res.preedit = search.text;
		else
			impre(&im, &res.preedit);
	}
	chansend(kr->reply, &res);
}

void
imthread(void*)
{
	Keyreq kr;

	threadsetname("im");
	init();
	for(;;){
		chanrecv(keyc, &kr);
		imhandlekey(&kr);
	}
}