#include <stdarg.h>
#include <stdbit.h>
#include <assert.h>

#include "ir.h"
#include "typ.h"
#include "strio.h"

/* node lists */

void nodelist_fit(NodeList *l, u32 sz, Arena *a) {
	if (l->cap) {
		if (sz > l->cap) {
			u32 cap = stdc_bit_ceil(sz);
			l->data = resize(a, l->data, l->cap, cap);
			l->cap = cap;
		}
	} else if (sz > 1) {
		u32 cap = stdc_bit_ceil(sz);
		Node **data = new_arr(a, Node *, cap);
		data[0] = l->sbo;
		l->data = data;
		l->cap = cap;
	}
}

void nodelist_push(NodeList *l, Node *n, Arena *a) {
	nodelist_fit(l, l->len + 1, a);
	Node **p = nodelist_nth(l, l->len++);
	*p = n;
}

void nodelist_remove(NodeList *l, Node *n) {
	Node **data = nodelist_data(l);
	for (unsigned i = 0; i < l->len; i++) {
		if (data[i] == n) {
			l->len--;
			if (i < l->len) {
				memmove(&data[i], &data[i+1], (l->len - i) * sizeof(Node *));
			}
			break;
		}
	}
}

void nodelist_remove_unordered(NodeList *l, Node *p) {
	Node **data = nodelist_data(l);
	unsigned i = l->len;
	while (i) {
		i--;
		if (data[i] == p) {
			l->len--;
			if (i < l->len) {
				data[i] = data[l->len];
			}
			break;
		}
	}
}

/* nodes */

const char *node_type_name(NodeType t) {
	static const char *names[] = {
#define X(n, s) s,
		NODE_TYPE_LIST
#undef X
	};
	return names[t];
}

void node_die(Node *n, Graph *p) {
	assert(n->op != N_DEAD);
	n->op = N_DEAD;
	n->prev_free = p->pool->free_list;
	p->pool->free_list = n;
}

void node_del_out(Node *n, Node *p) {
	nodelist_remove_unordered(&n->out, p);
}

void node_del_in(Node *n, Node *p) {
	nodelist_remove(&n->in, p);
}

static inline int node_should_die(Node *n) {
	return n->in.len == 0 && n->out.len == 0;
}

void node_kill(Node *n, Graph *p) {
	if (p->ctrl == n) {
		/* probably this is fine */
		p->ctrl = CTRL(n);
	}
	for (u32 i = 0; i < n->in.len; i++) {
		Node *o = IN(n, i);
		if (o) {
			node_del_out(o, n);
			if (node_should_die(o)) node_die(o, p);
		}
	}
	for (u32 i = 0; i < n->out.len; i++) {
		Node *o = OUT(n, i);
		node_del_in(o, n);
		if (node_should_die(o)) node_die(o, p);
	}
	node_die(n, p);
}

void node_add_out(Graph *p, Node *a, Node *b) {
	nodelist_push(&a->out, b, p->pool->arena);
}

void node_add_in(Graph *p, Node *a, Node *b) {
	nodelist_push(&a->in, b, p->pool->arena);
}

void node_set_in(Graph *p, Node *n, int idx, Node *to) {
	Node *in = IN(n, idx);
	node_add_out(p, to, n);
	node_del_out(in, n);
	IN(n, idx) = to;
	if (in->out.len < 1) node_kill(in, p);
}

void node_add(Graph *p, Node *src, Node *dest) {
	assert(dest->op != N_DEAD);
	node_add_in(p, dest, src);
	if (!src) return;
	assert(src->op != N_DEAD);
	node_add_out(p, src, dest);
	if (dest->src_pos.n == 0) dest->src_pos = src->src_pos;
	else if (src->src_pos.n != 0) {
		int lo = dest->src_pos.ofs < src->src_pos.ofs ? dest->src_pos.ofs : src->src_pos.ofs;
		int hi = dest->src_pos.ofs + dest->src_pos.n > src->src_pos.ofs + src->src_pos.n ? dest->src_pos.ofs + dest->src_pos.n : src->src_pos.ofs + src->src_pos.n;
		dest->src_pos = (LexSpan) { lo, hi - lo };
	}
}

void node_remove(Graph *p, Node *src, Node *dest) {
	assert(dest->op != N_DEAD);
	node_del_in(dest, src);
	if (node_should_die(dest)) node_die(dest, p);
	if (src) {
		assert(src->op != N_DEAD);
		node_del_out(src, dest);
		if (src->out.len < 1) node_kill(src, p);
	}
}

static int global_node_count = 0;

Node *node_new_empty(Graph *p, NodeType t) {
	Node *n;
	if (p->pool->free_list) {
		n = p->pool->free_list;
		assert(n->op == N_DEAD);
		p->pool->free_list = n->prev_free;
		n->in.len = 0;
		n->out.len = 0;
		n->walked = 0;
		n->src_pos = (LexSpan) { 0 };
		n->val = (Value) { 0 };
	} else {
		n = new(p->pool->arena, Node);
	}
	n->op = t;
	n->id = global_node_count++;
	return n;
}

Node *node_newv(Graph *p, NodeType t, Node *ctrl, ...) {
	Node *node = node_new_empty(p, t);
	va_list ap;
	/* do inputs all at once to decrease chance of arena_realloc() fragmenting */

	va_start(ap, ctrl);
	node_add_in(p, node, ctrl);
	for (;;) {
		Node *n = va_arg(ap, Node *);
		if (!n) break;
		node_add_in(p, node, n);
	}
	va_end(ap);

	va_start(ap, ctrl);
	if (ctrl) node_add_out(p, ctrl, node);
	for (;;) {
		Node *n = va_arg(ap, Node *);
		if (!n) break;
		node_add_out(p, n, node);
	}
	va_end(ap);

	return node;
}

Node *node_dedup_lit(Graph *p, Value v) {
	/* TODO: this is probably real inefficient for large procedure graphs,
	 * but does it matter? how many nodes are direct children of the start node?
	 * how many literals even usually occur in a procedure? */
	for (u32 i = 0; i < p->start->out.len; i++) {
		Node *t = OUT(p->start, i);
		if (t->op == N_LIT && type_eql(&t->type, &v.type) && t->val.i == v.i) {
			return t;
		}
	}
	return NULL;
}

Node *node_new_lit(Graph *p, Value v) {
	Node *t = node_dedup_lit(p, v);
	if (t) return t;
	Node *n = node_new(p, N_LIT, NULL, p->start);
	n->val = v;
	return n;
}

Node *node_new_lit_i64(Graph *p, int64_t i) {
	return node_new_lit(p, (Value) { { .lvl = T_CONST, .t = T_INT }, { .i = i } });
}

Node *node_new_lit_bool(Graph *p, int b) {
	return node_new_lit(p, (Value) { { .lvl = T_CONST, .t = T_BOOL }, { .i = b } });
}

/* types */

int type_eql(Type *a, Type *b) {
	if (a->t != b->t) return 0;
	if (a->lvl != b->lvl) return 0;
	if (a->next != b->next) return 0;
	return a->next ? type_eql(a->next, b->next) : 1;
}

int type_base_eql(Type *a, Type *b) {
	if (a->t != b->t) return 0;
	if (a->next != b->next) return 0;
	return a->next ? type_base_eql(a->next, b->next) : 1;
}

int value_eql(Value *a, Value *b) {
	if (!type_eql(&a->type, &b->type)) return 0;
	return a->i == b->i;
}

Str type_desc(Type *t, Arena *arena) {
	(void)arena;
	switch (t->lvl) {
	case T_CTRL: return S("ctrl");
	case T_XCTRL: return S("~ctrl");
	default: break;
	}
	switch (t->t) {
	case T_TUPLE: return S("tuple");
	case T_BOOL: return S("bool");
	case T_INT: return S("i64");
	case T_PTR: return str_fmt(arena, "^%S", type_desc(t->next, arena));
	default: return S("N/A");
	}
}

void type_err(Node *n, Lexer *l) {
	Str s = S("");
	for (u32 i = 0; i < n->in.len; i++) {
		if (i > 0) str_cat(&s, S(", "), &l->arena);
		str_cat(&s, type_desc(&IN(n, i)->type, &l->arena), &l->arena);
	}
	lex_error_at(l, n->src_pos, LE_ERROR, str_fmt(&l->arena, "type error %s (%S)", node_type_name(n->op), s));
}

void type_expected(Type *want, Node *n, Lexer *l) {
	if (type_base_eql(want, &n->type)) return;
	lex_error_at(l, n->src_pos, LE_ERROR, str_fmt(&l->arena, "type error: expected %S, but got %S",
				type_desc(want, &l->arena), type_desc(&n->type, &l->arena)));
}

static int type_ok(Node *n) {
	switch (n->op) {
	case N_PHI:
		n->type = (Type) { .lvl = T_TOP, .t = IN(n, 1)->type.t };
		for (u32 i = 2; i < n->in.len; i++) {
			if (!type_base_eql(&IN(n, i)->type, &n->type)) {
				return 0;
			}
		}
		return 1;
	case N_OP_NEG:
		n->type = (Type) { .lvl = T_TOP, .t = T_INT };
		return CAR(n)->type.t == T_INT;
	case N_OP_NOT:
		n->type = (Type) { .lvl = T_TOP, .t = CAR(n)->type.t };
		return CAR(n)->type.t == T_INT || CAR(n)->type.t == T_BOOL;
	case N_OP_AND: case N_OP_OR: case N_OP_XOR:
		n->type = (Type) { .lvl = T_TOP, .t = CAR(n)->type.t };
		return (CAR(n)->type.t == T_INT && CDR(n)->type.t == T_INT)
			|| (CAR(n)->type.t == T_BOOL && CDR(n)->type.t == T_BOOL);
	case N_OP_ADD: case N_OP_SUB: case N_OP_MUL: case N_OP_DIV:
	case N_OP_SHL: case N_OP_SHR:
		n->type = (Type) { .lvl = T_TOP, .t = T_INT };
		return CAR(n)->type.t == T_INT && CDR(n)->type.t == T_INT;
	case N_CMP_LES: case N_CMP_GTR:
	case N_CMP_LTE: case N_CMP_GTE:
		n->type = (Type) { .lvl = T_TOP, .t = T_BOOL };
		return CAR(n)->type.t == T_INT && CDR(n)->type.t == T_INT;
	case N_CMP_EQL:
	case N_CMP_NEQ:
		n->type = (Type) { .lvl = T_TOP, .t = T_BOOL };
		return type_base_eql(&CAR(n)->type, &CDR(n)->type);
			/* (CAR(n)->type.t == T_INT && CDR(n)->type.t == T_INT)
			|| (CAR(n)->type.t == T_BOOL && CDR(n)->type.t == T_BOOL); */
	default:
		return 1;
	}
}

void type_check(Node *n, Lexer *l) {
	if (!type_ok(n)) type_err(n, l);
}

int node_uninit(Node *n) {
	return n->op == N_UNINIT;
}

int node_maybe_uninit(Node *n) {
	if (node_uninit(n)) return 1;
	for (u32 i = 0; i < n->in.len; i++) {
		if (IN(n,i) && node_maybe_uninit(IN(n,i))) {
			return 1;
		}
	}
	return 0;
}