#define _GNU_SOURCE 		/* asprintf */
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include "arch.h"
#include "func.h"
#include "node.h"
#include "ply.h"
#include "sym.h"
#include "type.h"


/* :map */

static struct type *global_map_ktype(struct node *n)
{
	struct node *map, *key;
	struct type *ktype;
	struct tfield *kfields, *f;
	int i, nargs = node_nargs(n);
	char *kname;

	map = n->expr.args;

	if (nargs == 2)
		return map->next->sym->type;

	ktype = calloc(1, sizeof(*ktype));
	assert(ktype);

	kfields = calloc(nargs, sizeof(*kfields));
	assert(kfields);

	for (key = map->next, f = kfields, i = 0; key; key = key->next, f++, i++) {
		asprintf(&f->name, "k%d", i);
		f->type = key->sym->type;
	}

	asprintf(&ktype->sou.name, ":%s_key", map->ident.name);
	ktype->ttype = T_STRUCT;
	ktype->sou.fields = kfields;

	type_add(ktype);
	return ktype;
}

static int global_map_type_infer(const struct func *func, struct node *n)
{
	struct node *map = n->expr.args;

	if (n->sym->type || !map->sym->type)
		return 0;

	assert(map->sym->type->ttype == T_MAP);

	/* given `m[key]` where m's type is known, infer that the
	 * expression's type is equal to m's value type. */
	n->sym->type = map->sym->type->map.vtype;
	return 0;
}

static int global_map_static_validate(const struct func *func, struct node *n)
{
	if (n->expr.args->ntype != N_IDENT) {
		_e("%#N: %N is not subscriptable.\n", n, n);
		return -EINVAL;
	}

	return 0;
}

/* :assign */

static int global_assign_type_infer_map(struct node *n)
{
	struct node *map, *key;
	struct type *ktype;

	map = n->expr.args;

	for (key = map->next; key; key = key->next) {
		if (type_sizeof(key->sym->type) < 0)
			return 0;
	}

	map->sym->type = type_map_of(global_map_ktype(n), n->sym->type);
	return 0;
}

static int global_assign_type_infer(const struct func *func, struct node *n)
{
	struct node *lval, *rval;

	lval = n->expr.args;
	rval = lval->next;

	if (!rval->sym->type)
		return 0;

	if (!lval->sym->type) {
		/* given `a = b` where b's type is known but not a's,
		 * infer that a's type must be equal to b's */
		lval->sym->type = rval->sym->type;

		if (node_is_map(lval))
			return global_assign_type_infer_map(lval);

		return 0;
	}

	if (type_compatible(lval->sym->type, rval->sym->type))
		return 0;

	_e("%#N: can't assign %N (type '%T'), to %N (type '%T').\n",
	   n, rval, rval->sym->type, lval, lval->sym->type);
	return -EINVAL;
}

static int global_assign_static_validate(const struct func *func, struct node *n)
{
	struct node *lval;
	int nargs = node_nargs(n);

	if (nargs != 2) {
		_e("%#N: expected 2 arguments, %d given.\n", n, nargs);
		return -EINVAL;
	}

	lval = n->expr.args;

	if (node_is_map(lval) || (lval->ntype == N_IDENT))
		return 0;

	_e("%#N: %N is not assignable.\n", n, lval);
	return -EINVAL;
}


/* pid */

struct type t_pid = {
	.ttype = T_TYPEDEF,

	.tdef = { .name = ":pid", .type = &t_u32 },
};

struct type t_pid_func = {
	.ttype = T_FUNC,

	.func = { .type = &t_pid },
};

/* time */

struct type t_time = {
	.ttype = T_TYPEDEF,	/* TODO: should be a T_FUNC with a static
				 * signature */

	.tdef = { .name = ":time", .type = &t_s64 },
};

struct type t_time_func = {
	.ttype = T_FUNC,

	.func = { .type = &t_time },
};

struct type t_block_func = {
	.ttype = T_FUNC,

	.func = { .type = &t_void, .vargs = 1 },
};

struct tfield f_assign[] = {
	{ .type = &t_void },
	{ .type = &t_void },

	{ .type = NULL }
};

struct type t_assign_func = {
	.ttype = T_FUNC,

	.func = { .type = &t_void, .args = f_assign },
};

static const struct func global_funcs[] = {
	{ .name = ":block", .type = &t_block_func, },

	{ .name = "+", },
	{ .name = "-", },
	
	{
		.name = ":assign",
		.type = &t_assign_func,
		.type_infer = global_assign_type_infer,
		.static_validate = global_assign_static_validate,
	},
	{
		.name = ":map",
		/* .type = t_map_func, */
		.type_infer = global_map_type_infer,
		.static_validate = global_map_static_validate,
	},

	{ .name = "pid",  .type = &t_pid_func, },
	{ .name = "time", .type = &t_time_func, },

	{ .name = "quantize", },
	
	{ .name = NULL }
};

static const struct func global_num_func = {
	.name = ":num",
	.type = &t_int,
};

struct type t_string_array = {
	.ttype = T_ARRAY,

	.array = { .type = &t_char, .len = 64 }, /* TODO: tunable */
};

struct type t_string = {
	.ttype = T_TYPEDEF,

	.tdef = { .name = ":string", .type = &t_string_array },
};

static const struct func global_string_func = {
	.name = ":string",
	.type = &t_string,
};

static const struct func global_ident_func = {
	.name = ":ident",
};

static const struct func *global_sym_alloc_expr(struct node *n)
{
	const struct func *func;
	int err;

	for (func = global_funcs; func->name; func++) {
		if (strcmp(func->name, n->expr.func))
			continue;

		return func;
	}

	return NULL;
}

int global_sym_alloc(struct prog *prog, struct node *n)
{
	const struct func *func;
	struct symtab *st = prog->locals;
	int err;

	switch (n->ntype) {
	case N_EXPR:
		func = global_sym_alloc_expr(n);
		break;
	case N_IDENT:
		st = prog->globals;
		func = &global_ident_func;
		break;
	case N_NUM:
		func = &global_num_func;
		break;
	case N_STRING:
		func = &global_string_func;
		break;
	}

	if (!func)
		return -ENOENT;

	err = func_static_validate(func, n);
	if (err)
		return err;

	n->sym = sym_alloc(st, n, func);
	n->sym->type = func_return_type(func);
	return 0;
}

int global_probe(struct prog *prog)
{
	return 0;
}

struct provider global = {
	.name = ":",

	.sym_alloc = global_sym_alloc,
	.probe = global_probe,
};

__attribute__((constructor))
static void global_init(void)
{
	provider_register(&global);
}