/*
  Copyright (C) 2019, 2020 Leo Tenenbaum.
  This file is part of toc. toc is distributed under version 3 of the GNU General Public License, without any warranty whatsoever.
  You should have received a copy of the GNU General Public License along with toc. If not, see <https://www.gnu.org/licenses/>.


  these copy functions MUST be used before typing!!!! (except for copy_val)

  ----- 
  IMPORTANT:   
  These functions are like memcpy, in that in and out must not overlap!
  -----  
*/

typedef struct {
	Allocator *allocr;
	Block *block;
} Copier;

static Expression *copy_expr_(Copier *c, Expression *in);
static void copy_expr(Copier *c, Expression *out, Expression *in);
static void copy_decl(Copier *c, Declaration *out, Declaration *in);
enum {
	  COPY_BLOCK_DONT_CREATE_IDENTS = 0x01
};
static void copy_block(Copier *c, Block *out, Block *in, U8 flags);
static void copy_type(Copier *c, Type *out, Type *in);
static Type *copy_type_(Copier *c, Type *in);

static Copier copier_create(Allocator *a, Block *b) {
	Copier c;
	c.allocr = a;
	c.block = b;
	return c;
}

static void copy_val(Allocator *a, Value *out, Value in, Type *t) {
	assert(t->flags & TYPE_IS_RESOLVED);
	switch (t->kind) {
	case TYPE_BUILTIN:
		if (t->builtin == BUILTIN_VARARGS) {
			size_t n = arr_len(in.varargs);
			out->varargs = NULL;
			arr_set_lena(&out->varargs, n, a);
			for (size_t i = 0; i < n; ++i) {
				Copier c = copier_create(a, NULL); /* since the type is resolved, it doesn't matter that the block is wrong */
				out->varargs[i].type = copy_type_(&c, in.varargs[i].type);
				out->varargs[i].val = in.varargs[i].val;
			}
			break;
		}
		/* fallthrough */
	case TYPE_FN:
	case TYPE_PTR:
	case TYPE_SLICE:
	case TYPE_VOID:
	case TYPE_UNKNOWN:
		*out = in;
		break;
	case TYPE_ARR: {
		size_t bytes = (size_t)t->arr.n * compiler_sizeof(t->arr.of);
		out->arr = allocr_malloc(a, bytes);
		memcpy(out->arr, in.arr, bytes);
	} break;
	case TYPE_TUPLE: {
		size_t bytes = arr_len(t->tuple) * sizeof(*out->tuple);
		out->tuple = allocr_malloc(a, bytes);
		memcpy(out->tuple, in.tuple, bytes);
	} break;
	case TYPE_STRUCT: {
		size_t bytes = compiler_sizeof(t);
		out->struc = allocr_malloc(a, bytes);
		memcpy(out->struc, in.struc, bytes);
	} break;
	case TYPE_EXPR:
		assert(0);
		break;
	}
}

static void copy_val_full(Copier *c, Value *out, Value in, Type *t) {
	if (type_is_builtin(t, BUILTIN_TYPE)) {
		Type *new_type = allocr_malloc(c->allocr, sizeof *new_type);
		copy_type(c, new_type, in.type);
		out->type = new_type;
	} else {
		copy_val(c->allocr, out, in, t);
	}
}

static void copy_struct(Copier *c, StructDef *out, StructDef *in) {
	*out = *in;
	size_t nfields = arr_len(in->fields);
	out->fields = NULL;

	out->scope = in->scope;
	idents_create(&out->scope.idents, c->allocr, &out->scope);
	
	Block *prev = c->block;
	copy_block(c, &out->scope, &in->scope, 0);
	c->block = &out->scope;

	arr_set_lena(&out->fields, nfields, c->allocr);
	for (size_t i = 0; i < nfields; ++i) {
		Field *fout = &out->fields[i];
		Field *fin = &in->fields[i];
		*fout = *fin;
		copy_type(c, &fout->type, &fin->type);
	}
	size_t nparams = arr_len(in->params);
	out->params = NULL;
	arr_set_lena(&out->params, nparams, c->allocr);
	for (size_t i = 0; i < nparams; ++i) {
		copy_decl(c, &out->params[i], &in->params[i]);
	}
	out->constants = NULL;
	size_t nconstants = arr_len(in->constants);
	arr_set_lena(&out->constants, nconstants, c->allocr);
	for (size_t i = 0; i < nconstants; ++i) {
		copy_decl(c, &out->constants[i], &in->constants[i]);
	}
	c->block = prev;
}

/* works on unresolved and resolved types (for inference) */
static void copy_type(Copier *c, Type *out, Type *in) {
	*out = *in;
	switch (in->kind) {
	case TYPE_BUILTIN:
	case TYPE_VOID:
	case TYPE_UNKNOWN:
		break;
	case TYPE_EXPR:
		out->expr = copy_expr_(c, in->expr);
		break;
	case TYPE_FN: {
		size_t ntypes = arr_len(in->fn.types);
		out->fn.types = NULL;
		arr_set_lena(&out->fn.types, ntypes, c->allocr);
		for (size_t i = 0; i < ntypes; ++i) {
			copy_type(c, &out->fn.types[i], &in->fn.types[i]);
		}
	} break;
	case TYPE_TUPLE: {
		size_t ntypes = arr_len(in->tuple);
		out->tuple = NULL;
		arr_set_lena(&out->tuple, ntypes, c->allocr);
		for (size_t i = 0; i < ntypes; ++i) {
			copy_type(c, &out->tuple[i], &in->tuple[i]);
		}
	} break;
	case TYPE_ARR:
		if (in->flags & TYPE_IS_RESOLVED) {
			out->arr.n = in->arr.n;
		} else {
			out->arr.n_expr = copy_expr_(c, in->arr.n_expr);
		}
		out->arr.of = copy_type_(c, in->arr.of);
		break;
	case TYPE_PTR:
		out->ptr = copy_type_(c, in->ptr);
		break;
	case TYPE_SLICE:
		out->slice = copy_type_(c, in->slice);
		break;
	case TYPE_STRUCT: {
		if (in->flags & TYPE_IS_RESOLVED) {
			/* we don't actually need to make a copy of the struct for inference */
		} else {
			/* 
			   it's okay to copy the struct definition here, because before resolving,
			   only one thing can point to a given StructDef
			*/
			out->struc = allocr_malloc(c->allocr, sizeof *out->struc);
			copy_struct(c, out->struc, in->struc);
		}
	} break;
	}
}

static Type *copy_type_(Copier *c, Type *in) {
	Type *out = allocr_malloc(c->allocr, sizeof *out);
	copy_type(c, out, in);
	return out;
}

static inline void *copier_malloc(Copier *c, size_t n) {
	return allocr_malloc(c->allocr, n);
}

enum {
	  COPY_FN_EXPR_DONT_COPY_HEADER = 0x01,
	  COPY_FN_EXPR_DONT_COPY_BODY = 0x02
};

static void copy_fn_expr(Copier *c, FnExpr *fout, FnExpr *fin, U8 flags) {
	*fout = *fin;
	bool copy_body = (flags & COPY_FN_EXPR_DONT_COPY_BODY) == 0;
	bool copy_header = (flags & COPY_FN_EXPR_DONT_COPY_HEADER) == 0;
	
	if (fin->flags & FN_EXPR_FOREIGN) {
		copy_expr(c, fout->foreign.name_expr = copier_malloc(c, sizeof *fin->foreign.name_expr), fin->foreign.name_expr);
		copy_expr(c, fout->foreign.lib_expr = copier_malloc(c, sizeof *fin->foreign.lib_expr), fin->foreign.lib_expr);
		copy_type(c, &fout->foreign.type, &fin->foreign.type);
		size_t nctypes = arr_len(fin->foreign.type.fn.types);
		fout->foreign.ctypes = copier_malloc(c, nctypes * sizeof(CType));
		memcpy(fout->foreign.ctypes, fin->foreign.ctypes, nctypes * sizeof(CType));
	} else {
		Block *prev = c->block;
		if (copy_body) {
			c->block = &fout->body;
			idents_create(&fout->body.idents, c->allocr, &fout->body);
		}
		if (copy_header) {
			size_t i;
			size_t nparam_decls = arr_len(fin->params);
			fout->params = NULL;
			arr_set_lena(&fout->params, nparam_decls, c->allocr);
			for (i = 0; i < nparam_decls; ++i)
				copy_decl(c, fout->params + i, fin->params + i);
			size_t nret_decls = arr_len(fin->ret_decls);
			if (fin->ret_decls) {
				fout->ret_decls = NULL;
				arr_set_lena(&fout->ret_decls, nret_decls, c->allocr);
				for (i = 0; i < nret_decls; ++i)
					copy_decl(c, fout->ret_decls + i, fin->ret_decls + i);
			}
			copy_type(c, &fout->ret_type, &fin->ret_type);
		}
		c->block = prev;
		if (copy_body) {
			copy_block(c, &fout->body, &fin->body, copy_body ? COPY_BLOCK_DONT_CREATE_IDENTS : 0);
		}
	}
}

static inline void copier_ident_translate(Copier *c, Identifier *i) {
	assert(c->block);
	assert(c->block->idents.scope == c->block);
	*i = ident_translate_forced(*i, &c->block->idents);
}

static void copy_expr(Copier *c, Expression *out, Expression *in) {
	Allocator *a = c->allocr;
	*out = *in;
	assert(!(in->flags & EXPR_FOUND_TYPE));
	switch (in->kind) {
	case EXPR_LITERAL_FLOAT:
	case EXPR_LITERAL_INT:
	case EXPR_LITERAL_STR:
	case EXPR_LITERAL_CHAR:
	case EXPR_LITERAL_BOOL:
		break;
	case EXPR_IDENT:
		copier_ident_translate(c, &out->ident);
		break;
	case EXPR_UNARY_OP:
		out->unary.of = copy_expr_(c, in->unary.of);
		break;
	case EXPR_BINARY_OP:
		out->binary.lhs = copy_expr_(c, in->binary.lhs);
		out->binary.rhs = copy_expr_(c, in->binary.rhs);
		break;
	case EXPR_IF: {
		IfExpr *iin = in->if_;
		IfExpr *iout = out->if_ = allocr_malloc(a, sizeof *iout);
		*iout = *iin;
		if (iin->cond)
			iout->cond = copy_expr_(c, iin->cond);
		if (iin->next_elif)
			iout->next_elif = copy_expr_(c, iin->next_elif);
		copy_block(c, &iout->body, &iin->body, 0);
	} break;
	case EXPR_WHILE: {
		WhileExpr *win = in->while_;
		WhileExpr *wout = out->while_ = allocr_malloc(a, sizeof *wout);
		*wout = *win;
		if (win->cond)
			wout->cond = copy_expr_(c, win->cond);
		copy_block(c, &wout->body, &win->body, 0);
	} break;
	case EXPR_FOR: {
		ForExpr *fin = in->for_;
		ForExpr *fout = allocr_malloc(a, sizeof *fout);
		out->for_ = fout;
		*fout = *fin;
		
		Block *prev = c->block;
		idents_create(&fout->body.idents, c->allocr, &fout->body);
		c->block = &fout->body;

		if (fout->index) {
			copier_ident_translate(c, &fout->index);
			fout->index->decl_kind = IDECL_EXPR;
			fout->index->decl_expr = out;
		}
		if (fout->value) {
			copier_ident_translate(c, &fout->value);
			fout->value->decl_kind = IDECL_EXPR;
			fout->value->decl_expr = out;
		}
		if (fin->flags & FOR_ANNOTATED_TYPE)
			copy_type(c, &fout->type, &fin->type);
		if (fin->flags & FOR_IS_RANGE) {
			fout->range.from = copy_expr_(c, fin->range.from);
			if (fin->range.to)
				fout->range.to = copy_expr_(c, fin->range.to);
			if (fin->range.step)
				fout->range.step = copy_expr_(c, fin->range.step);
		} else {
			fout->of = copy_expr_(c, fin->of);
		}
		c->block = prev;
		copy_block(c, &fout->body, &fin->body, COPY_BLOCK_DONT_CREATE_IDENTS);
	} break;
	case EXPR_FN:
		copy_fn_expr(c, out->fn = allocr_malloc(a, sizeof *out->fn), in->fn, 0);
		break;
	case EXPR_CAST: {
		CastExpr *cin = &in->cast;
		CastExpr *cout = &out->cast;
		copy_type(c, &cout->type, &cin->type);
		cout->expr = copy_expr_(c, cin->expr);
	} break;
	case EXPR_CALL: {
		CallExpr *cin = &in->call;
		CallExpr *cout = &out->call;
		copy_expr(c, cout->fn = allocr_malloc(a, sizeof *cout->fn), cin->fn);
		size_t nargs = arr_len(cin->args);
		cout->arg_exprs = NULL;
		arr_set_lena(&cout->args, nargs, a);
		for (size_t i = 0; i < nargs; ++i) {
			Argument *arg_in = &cin->args[i];
			Argument *arg_out = &cout->args[i];
			*arg_out = *arg_in;
			copy_expr(c, &arg_out->val, &arg_in->val);
		}
	} break;
	case EXPR_BLOCK:
		copy_block(c, out->block = allocr_malloc(a, sizeof *out->block), in->block, 0);
		break;
	case EXPR_TUPLE: {
		size_t nexprs = arr_len(in->tuple);
		out->tuple = NULL;
		arr_set_lena(&out->tuple, nexprs, a);
		for (size_t i = 0; i < nexprs; ++i)
			copy_expr(c, out->tuple + i, in->tuple + i);
	} break;
	case EXPR_C:
		out->c.code = copy_expr_(c, in->c.code);
		break;
	case EXPR_BUILTIN:
		out->builtin.which.expr = copy_expr_(c, in->builtin.which.expr); 
		break;
	case EXPR_SLICE: {
		SliceExpr *sin = &in->slice;
		SliceExpr *sout = &out->slice;
		copy_expr(c, sout->of = allocr_malloc(a, sizeof *sout->of), sin->of);
		if (sin->from)
			sout->from = copy_expr_(c, sin->from);
		if (sin->to)
			sout->to = copy_expr_(c, sin->to);
	} break;
	case EXPR_TYPE:
		copy_type(c, out->typeval = copier_malloc(c, sizeof *out->typeval), in->typeval);
		break;
	case EXPR_VAL:
		copy_val(a, &out->val, in->val, &in->type);
		break;
	case EXPR_NMS:
		out->nms = allocr_malloc(a, sizeof *out->nms);
		*out->nms = *in->nms;
		copy_block(c, &out->nms->body, &in->nms->body, 0);
		break;
	}
}

static Expression *copy_expr_(Copier *c, Expression *in) {
	Expression *out = allocr_malloc(c->allocr, sizeof *out);
	copy_expr(c, out, in);
	return out;
}

static void copy_decl(Copier *c, Declaration *out, Declaration *in) {
	*out = *in;
	assert(!(in->flags & DECL_FOUND_TYPE));
	
	if (in->flags & DECL_HAS_EXPR)
		copy_expr(c, &out->expr, &in->expr);
	if (in->flags & DECL_FOUND_VAL) {
		copy_val(c->allocr, &out->val, in->val, &in->type);
	}
	if (in->flags & DECL_ANNOTATES_TYPE)
		copy_type(c, &out->type, &in->type);
	out->idents = NULL;
	size_t nidents = arr_len(in->idents);
	arr_set_lena(&out->idents, nidents, c->allocr);
	for (size_t i = 0; i < nidents; ++i) {
		out->idents[i] = in->idents[i];
		assert(c->block);
		copier_ident_translate(c, &out->idents[i]);
		
		out->idents[i]->decl_kind = IDECL_DECL;
		out->idents[i]->decl = out;
	}
	
}

static void copy_stmt(Copier *c, Statement *out, Statement *in) {
	*out = *in;
	switch (in->kind) {
	case STMT_RET:
		if (in->ret.flags & RET_HAS_EXPR)
			copy_expr(c, &out->ret.expr, &in->ret.expr);
		break;
	case STMT_INCLUDE:
		if (in->flags & STMT_TYPED) {
			size_t nstmts = arr_len(in->inc.stmts);
			arr_set_lena(&out->inc.stmts, nstmts, c->allocr);
			for (size_t i = 0; i < nstmts; ++i) {
				copy_stmt(c, &out->inc.stmts[i], &in->inc.stmts[i]);
			}
		} else {
			copy_expr(c, &out->inc.filename, &in->inc.filename);
		}
		break;
	case STMT_EXPR:
		copy_expr(c, &out->expr, &in->expr);
		break;
	case STMT_DECL:
		copy_decl(c, out->decl = allocr_malloc(c->allocr, sizeof *out->decl), in->decl);
		break;
	case STMT_MESSAGE:
		copy_expr(c, &out->message.text, &in->message.text);
		break;
	case STMT_DEFER:
		copy_stmt(c, out->defer = allocr_malloc(c->allocr, sizeof *out->defer), in->defer);
		break;
	case STMT_BREAK:
	case STMT_CONT:
		break;
	}
}

/* COPY_BLOCK_DONT_CREATE_IDENTS is for copy_fn_expr */
static void copy_block(Copier *c, Block *out, Block *in, U8 flags) {
	assert(!(in->flags & BLOCK_FINDING_TYPES));
	Identifiers out_idents = out->idents;
	*out = *in;
	out->parent = c->block;
	if (flags & COPY_BLOCK_DONT_CREATE_IDENTS)
		out->idents = out_idents; /* reset Identifiers */
	size_t nstmts = arr_len(in->stmts);
	out->stmts = NULL;
	Block *prev = c->block;
	c->block = out;
	if (in->ret_expr)
		out->ret_expr = copy_expr_(c, in->ret_expr);
	if (!(flags & COPY_BLOCK_DONT_CREATE_IDENTS))
		idents_create(&out->idents, c->allocr, out);
	arr_set_lena(&out->stmts, nstmts, c->allocr);
	for (size_t i = 0; i < nstmts; ++i) {
		copy_stmt(c, &out->stmts[i], &in->stmts[i]);
	}
	c->block = prev;
}