#include "all.h"

static FILE *outfp;

static void pri(const char *fmt, ...);

static void
gentype(const struct type *ty) {
   assert(ty);
   switch (ty->t) {
   case TYvoid:
      pri("void");
      break;
   case TYbool:
      pri("bool");
      break;
   case TYint:
      pri("%sint%z_t", ty->int_signed ? "" : "u",
                  8 * ty->size);
      break;
   case TYfloat:
      pri("%s", ty->size == 4 ? "float" : "double");
      break;
   case TYptr:
      pri("%t *", ty->child);
      break;
   case TYarr:
      assert(ty->length >= 0);
   case TYslice:
      assert(ty->_cname);
      pri("%s", ty->_cname);
      return;
   case TYfn:
      assert(ty->_cname);
      pri("%s", ty->_cname);
      return;
   }
   if (ty->konst)
      pri(" const");
}

static void
pristring(const char *s, u64 n) {
   extern int isprint(int);
   pri("\"");
   for (int i = 0; i < n; ++i) {
      if (isprint(s[i]))
         pri("%c", s[i]);
      else
         fprintf(outfp, "\\%.3o", s[i]);
   }
   pri("\"");
}

static void genexpr(struct expr *expr);

void
pri(const char *fmt, ...) {
   va_list ap;
   unsigned ch;
   const char *S;
   int ws;

   va_start(ap, fmt);
   for (char c; (c = *fmt++);) {
      if (c != '%') {
         fputc(c, outfp);
         continue;
      }
      switch ((c = *fmt++)) {
      case '%':
         fputc(c, outfp);
         break;
      case 'c':
         ch = bswap32(va_arg(ap, int));
         while (ch) {
            if (ch & 0xFF)
               fputc(ch, outfp);
            ch >>= 8;
         }
         break;
      case 'd':
         fprintf(outfp, "%d", va_arg(ap, int));
         break;
      case 'U':
         fprintf(outfp, "%llu", (unsigned long long)va_arg(ap, u64));
         break;
      case 'z':
         fprintf(outfp, "%zu", va_arg(ap, size_t));
         break;
      case 'f':
         fprintf(outfp, "%.20f", va_arg(ap, double));
         break;
      case 's':
         fprintf(outfp, "%s", va_arg(ap, const char *));
         break;
      case 'w':
         ws = va_arg(ap, int);
         for (int i = 0; i < ws; ++i)
            fprintf(outfp, "   ");
         break;
      case 'S':
         S = va_arg(ap, const char *);
         pristring(S, va_arg(ap, u64));
         break;
      case 't':
         gentype(va_arg(ap, const struct type *));
         break;
      case 'e':
         genexpr(va_arg(ap, struct expr *));
         break;
      default:
         fprintf(outfp, "pri(): bad fmt '%%%c'\n", c);
         abort();
         break;
      }
   }
   va_end(ap);
}

static void genblock(struct blockstmt block);

static void
genexpr(struct expr *ex) {
   const struct type *ty = ex->ty;
   switch (ex->t) {
   case Eintlit:
      if (ty == ty_int)
         pri("%U", ex->i);
      else
         pri("((%t)%U)", ty, ex->i);
      break;
   case Eflolit:
      pri("%f%s", ex->f, ty->size == 4 ? "f" : "");
      break;
   case Estrlit:
      pri("%S", ex->strlit.d, ex->strlit.n);
      break;
   case Eboolit:
      pri("((_Bool)%U)", ex->i);
      break;
   case Enullit:
      pri("NULL");
      break;
   case Ename:
      if (ex->ref->t == Dfn &&  ex->ref->_cname && *ex->ref->_cname)
         pri("%s", *ex->ref->_cname);
      else
         pri("%s", ex->ref->name);
      break;
   case Eprefix:
      pri("%c(%e)", ex->unop.op, ex->unop.child);
      break;
   case Epostfix:
      pri("(%e)%c", ex->unop.op, ex->unop.child);
      break;
   case Ebinop:
      pri("(%e %c %e)", ex->binop.lhs, ex->binop.op, ex->binop.rhs);
      break;
   case Econd:
      pri("(%e) ? (%e) : (%e)", ex->cond.test, ex->cond.t, ex->cond.f);
      break;
  case Ecall:
      pri("%e(", ex->call.callee);
      for (int i = 0; i < ex->call.args.n; ++i) {
         pri("%e", &ex->call.args.d[i]);
         if (i < ex->call.args.n - 1)
            pri(", ");
      }
      pri(")");
      break;
   case Eindex:
      pri("%e[%e]", ex->index.lhs, ex->index.rhs);
      break;

   }
}

static void genfn(const char *cname, struct fn *fn);

static void
genstmt(struct stmt *stmt) {
   switch (stmt->t) {
   case Sblock:
      genblock(stmt->block);
      break;
   case Sexpr:
      genexpr(&stmt->expr);
      pri(";\n");
      break;
   case Sdecl:
      ; struct decl decl = stmt->decl;
      switch (decl.t) {
      case Dvar:
         pri("%t %s", decl.var.ty, decl.name);
         if (decl.var.ini)
            pri(" = %e", decl.var.ini);
         pri(";\n");
         break;
      case Dfn:
         if (decl.externp)
            genfn(decl.fn.name, &decl.fn);
         break;
      case Dtype: case Dmacro:
         break;
      }
      break;
   case Sifelse:
      pri("if (%e) ", &stmt->ifelse.test);
      genblock(stmt->ifelse.t);
      if (stmt->ifelse.f) {
         pri("else ");
         genstmt(stmt->ifelse.f);
      }
      break;
   case Swhile:
      pri("while (%e) ", &stmt->loop.test);
      genblock(stmt->loop.body);
      break;
   case Sfor:
      pri("for (");
      if (stmt->loop.ini)
         genstmt(stmt->loop.ini);
      pri("%e;", &stmt->loop.test);
      if (stmt->loop.next)
         pri(" %e", &stmt->loop.next);
      pri(")");
      genblock(stmt->loop.body);
   case Siswitch:
      break;
   case Sreturn:
      pri("return");
      if (stmt->retex)
         pri(" %e", stmt->retex);
      pri(";\n");
      break;
   }
}

static void
genblock(struct blockstmt block) {
   pri("{\n");
   for (int i = 0; i < block.stmts.n; ++i)
      genstmt(&block.stmts.d[i]);
   pri("}\n");
}

static void
liftnestedex(struct expr *expr) {
   // TODO implement when statement expressions exist
   //switch (expr->t) {
   //}
}

#define blocktostmt(Block) \
   &(struct stmt) {Sblock, .block = Block} 

static void // lift nested fns and static vars
liftnested(struct stmt *stmt) {
   static int id;
   if (!stmt)
      return;
   switch (stmt->t) {
   case Sblock:
      for (int i = 0; i < stmt->block.stmts.n; ++i)
         liftnested(&stmt->block.stmts.d[i]);
      break;
   case Sexpr:
      liftnestedex(&stmt->expr);
      break;
   case Sdecl:
      switch (stmt->decl.t) {
      case Dfn:
         if (stmt->decl.fn.body) {
            *stmt->decl._cname = xasprintf("__f%s_%d", stmt->decl.fn.name, id++);
            genfn(*stmt->decl._cname, &stmt->decl.fn);
         }
         break;
      case Dvar:
         liftnestedex(stmt->decl.var.ini);
         break;
      default:
         break;
      }
      break;
   case Sifelse:
      liftnested(stmt->ifelse.f);
      liftnested(blocktostmt(stmt->ifelse.t));
      break;
   case Swhile:
      liftnested(blocktostmt(stmt->loop.body));
      break;
   case Sfor:
      liftnested(stmt->loop.ini);
      liftnestedex(&stmt->loop.test);
      liftnestedex(stmt->loop.next);
      liftnested(blocktostmt(stmt->loop.body));
      break;
   case Siswitch:
      liftnestedex(&stmt->iswitch.test);
      for (int i = 0; i < stmt->iswitch.cs.n; ++i) {
         // not visiting constant exprs
         liftnested(blocktostmt(stmt->iswitch.cs.d[i].t));
      }
      if (stmt->iswitch.f)
         liftnested(blocktostmt(*stmt->iswitch.f));
      break;
   case Sreturn:
      liftnestedex(stmt->retex);
      break;
   }
}

static void
genfn(const char *cname, struct fn *fn) {
   liftnested(fn->body);
   if (fn->body)
      pri("\n");
   pri("%t %s(", fn->retty, cname);
   for (int i = 0; i < fn->params.n; ++i) {
      pri("%t %s", fn->params.d[i].ty, fn->params.d[i].name);
      if (i < fn->params.n - 1 || fn->variadic)
         pri(", ");
   }
   if (fn->variadic)
      pri("...");
   pri(")");
   if (!fn->body) {
      pri(";\n");
   } else {
      genblock(fn->body->block);
   }

}

static void
gendecl(struct decl *decl, bool toplevel) {
   switch (decl->t) {
   case Dfn:
      if (!decl->externp)
         pri("static ");
      if (decl->fn.body)
         assert(toplevel);
      if (!*decl->_cname)
         *decl->_cname = (char *)decl->fn.name;
      genfn(*decl->_cname, &decl->fn);
      break;
   case Dvar:
      assert(!toplevel);
      break;
   case Dtype:
   case Dmacro:
      break;
   }
}

static void
defctype(const struct type *ty, void *_) {
   static int id;
   char **cname = (char **)&ty->_cname;

   if (!ty->_cname)
   switch (ty->t) {
   case TYvoid: case TYbool:
   case TYint: case TYfloat:
   case TYptr:
      return;
    case TYarr:
      assert(ty->length >= 0);
      defctype(ty->child, NULL);
      *cname = xasprintf("__ty%d", id++);
      pri("typedef %t %s[%U];\n", ty->child, *cname, ty->length);
      break;
   case TYslice:
      defctype(ty->child, NULL);
      *cname = xasprintf("__ty%d", id++);
      pri("typedef struct { %t *ptr; size_t len; } %s;\n",
          ty->child, *cname);
      break;
   case TYfn:
      *cname = xasprintf("__ty%d", id++);
      defctype(ty->fn.retty, NULL);
      for (int i = 0; i < ty->fn.params.n; ++i)
         defctype(ty->fn.params.d[i], NULL);
      pri("typedef %t %s(", ty->fn.retty, *cname);
      for (int i = 0; i < ty->fn.params.n; ++i) {
         pri("%t", ty->fn.params.d[i]);
         if (i < ty->fn.params.n - 1 || ty->fn.variadic)
            pri(", ");
      }
      if (ty->fn.variadic)
         pri("...");
      pri(");\n");


      break;
   }

}

static void
prelude() {
   pri("#include <stdint.h>\n"
       "#include <stddef.h>\n");
}

void
cgen(FILE *fp, const struct transunit *tu) {
   outfp = fp;

   prelude();
   visittypes(defctype, NULL);
   
   for (int i = 0; i < tu->decls.n; ++i) {
      gendecl(&tu->decls.d[i], 1);
   }
}