/*
 * call-seq:
 *     digest_obj.update(string) -> digest_obj
 *     digest_obj << string -> digest_obj
 *
 * Updates the digest using a given _string_ and returns self.
 *
 * The update() method and the left-shift operator are overridden by
 * each implementation subclass. (One should be an alias for the
 * other)
 */
static VALUE
rb_digest_instance_update(VALUE self, VALUE str)
{
    rb_raise(rb_eRuntimeError, "%s does not implement update()", RSTRING_PTR(rb_inspect(self)));
}

/*
 * call-seq:
 *     digest_obj == another_digest_obj -> boolean
 *     digest_obj == string -> boolean
 *
 * If a string is given, checks whether it is equal to the hex-encoded
 * hash value of the digest object.  If another digest instance is
 * given, checks whether they have the same hash value.  Otherwise
 * returns false.
 */
static VALUE
rb_digest_instance_equal(VALUE self, VALUE other)
{
    VALUE str1, str2;

    if (rb_obj_is_kind_of(other, rb_mDigest_Instance) == Qtrue) {
        str1 = rb_digest_instance_digest(0, 0, self);
        str2 = rb_digest_instance_digest(0, 0, other);
    } else {
        str1 = rb_digest_instance_to_s(self);
        str2 = other;
    }

    /* never blindly assume that subclass methods return strings */
    StringValue(str1);
    StringValue(str2);

    if (RSTRING_LEN(str1) == RSTRING_LEN(str2) &&
        rb_str_cmp(str1, str2) == 0) {
        return Qtrue;
    }
    return Qfalse;
}

/*
 * call-seq:
 *     digest_obj.block_length -> integer
 *
 * Returns the block length of the digest.
 *
 * This method is overridden by each implementation subclass.
 */
static VALUE
rb_digest_instance_block_length(VALUE self)
{
    rb_raise(rb_eRuntimeError, "%s does not implement block_length()", RSTRING_PTR(rb_inspect(self)));
}

/*
 * call-seq:
 *     digest_obj.digest -> string
 *     digest_obj.digest(string) -> string
 *
 * If none is given, returns the resulting hash value of the digest,
 * keeping the digest's state.
 *
 * If a _string_ is given, returns the hash value for the given
 * _string_, resetting the digest to the initial state before and
 * after the process.
 */
static VALUE
rb_digest_instance_digest(int argc, VALUE *argv, VALUE self)
{
    VALUE str, value;

    if (rb_scan_args(argc, argv, "01", &str) > 0) {
        rb_funcall(self, id_reset, 0);
        rb_funcall(self, id_update, 1, str);
        value = rb_funcall(self, id_finish, 0);
        rb_funcall(self, id_reset, 0);
    } else {
        VALUE clone = rb_obj_clone(self);

        value = rb_funcall(clone, id_finish, 0);
        rb_funcall(clone, id_reset, 0);
    }

    return value;
}

/*
 * call-seq:
 *     digest_obj.digest! -> string
 *
 * Returns the resulting hash value and resets the digest to the
 * initial state.
 */
static VALUE
rb_digest_instance_digest_bang(VALUE self)
{
    VALUE value = rb_funcall(self, id_finish, 0);
    rb_funcall(self, id_reset, 0);

    return value;
}

/*
 * call-seq:
 *     digest_obj.digest_length -> integer
 *
 * Returns the length of the hash value of the digest.
 *
 * This method should be overridden by each implementation subclass.
 * If not, digest_obj.digest().length() is returned.
 */
static VALUE
rb_digest_instance_digest_length(VALUE self)
{
    /* subclasses really should redefine this method */
    VALUE digest = rb_digest_instance_digest(0, 0, self);

    /* never blindly assume that #digest() returns a string */
    StringValue(digest);
    return INT2NUM(RSTRING_LEN(digest));
}

# File digest/lib/digest.rb, line 36
    def file(name)
      File.open(name, "rb") {|f|
        buf = ""
        while f.read(16384, buf)
          update buf
        end
      }
      self
    end

/*
 * call-seq:
 *     digest_obj.instance_eval { finish } -> digest_obj
 *
 * Finishes the digest and returns the resulting hash value.
 *
 * This method is overridden by each implementation subclass and often
 * made private, because some of those subclasses may leave internal
 * data uninitialized.  Do not call this method from outside.  Use
 * #digest!() instead, which ensures that internal data be reset for
 * security reasons.
 */
static VALUE
rb_digest_instance_finish(VALUE self)
{
    rb_raise(rb_eRuntimeError, "%s does not implement finish()", RSTRING_PTR(rb_inspect(self)));
}

/*
 * call-seq:
 *     digest_obj.hexdigest -> string
 *     digest_obj.hexdigest(string) -> string
 *
 * If none is given, returns the resulting hash value of the digest in
 * a hex-encoded form, keeping the digest's state.
 *
 * If a _string_ is given, returns the hash value for the given
 * _string_ in a hex-encoded form, resetting the digest to the initial
 * state before and after the process.
 */
static VALUE
rb_digest_instance_hexdigest(int argc, VALUE *argv, VALUE self)
{
    VALUE str, value;

    if (rb_scan_args(argc, argv, "01", &str) > 0) {
        rb_funcall(self, id_reset, 0);
        rb_funcall(self, id_update, 1, str);
        value = rb_funcall(self, id_finish, 0);
        rb_funcall(self, id_reset, 0);
    } else {
        VALUE clone = rb_obj_clone(self);

        value = rb_funcall(clone, id_finish, 0);
        rb_funcall(clone, id_reset, 0);
    }

    return hexencode_str_new(value);
}

/*
 * call-seq:
 *     digest_obj.hexdigest! -> string
 *
 * Returns the resulting hash value and resets the digest to the
 * initial state.
 */
static VALUE
rb_digest_instance_hexdigest_bang(VALUE self)
{
    VALUE value = rb_funcall(self, id_finish, 0);
    rb_funcall(self, id_reset, 0);

    return hexencode_str_new(value);
}

/*
 * call-seq:
 *     digest_obj.inspect -> string
 *
 * Creates a printable version of the digest object.
 */
static VALUE
rb_digest_instance_inspect(VALUE self)
{
    VALUE str;
    size_t digest_len = 32;     /* about this size at least */
    char *cname;

    cname = rb_obj_classname(self);

    /* #<Digest::ClassName: xxxxx...xxxx> */
    str = rb_str_buf_new(2 + strlen(cname) + 2 + digest_len * 2 + 1);
    rb_str_buf_cat2(str, "#<");
    rb_str_buf_cat2(str, cname);
    rb_str_buf_cat2(str, ": ");
    rb_str_buf_append(str, rb_digest_instance_hexdigest(0, 0, self));
    rb_str_buf_cat2(str, ">");
    return str;
}

/*
 * call-seq:
 *     digest_obj.length -> integer
 *     digest_obj.size -> integer
 *
 * Returns digest_obj.digest_length().
 */
static VALUE
rb_digest_instance_length(VALUE self)
{
    return rb_funcall(self, id_digest_length, 0);
}

/*
 * call-seq:
 *     digest_obj.new -> another_digest_obj
 *
 * Returns a new, initialized copy of the digest object.  Equivalent
 * to digest_obj.clone().reset().
 */
static VALUE
rb_digest_instance_new(VALUE self)
{
    VALUE clone = rb_obj_clone(self);
    rb_funcall(clone, id_reset, 0);
    return clone;
}

/*
 * call-seq:
 *     digest_obj.reset -> digest_obj
 *
 * Resets the digest to the initial state and returns self.
 *
 * This method is overridden by each implementation subclass.
 */
static VALUE
rb_digest_instance_reset(VALUE self)
{
    rb_raise(rb_eRuntimeError, "%s does not implement reset()", RSTRING_PTR(rb_inspect(self)));
}

/*
 * call-seq:
 *     digest_obj.length -> integer
 *     digest_obj.size -> integer
 *
 * Returns digest_obj.digest_length().
 */
static VALUE
rb_digest_instance_length(VALUE self)
{
    return rb_funcall(self, id_digest_length, 0);
}

/*
 * call-seq:
 *     digest_obj.to_s -> string
 *
 * Returns digest_obj.hexdigest().
 */
static VALUE
rb_digest_instance_to_s(VALUE self)
{
    return rb_funcall(self, id_hexdigest, 0);
}

/*
 * call-seq:
 *     digest_obj.update(string) -> digest_obj
 *     digest_obj << string -> digest_obj
 *
 * Updates the digest using a given _string_ and returns self.
 *
 * The update() method and the left-shift operator are overridden by
 * each implementation subclass. (One should be an alias for the
 * other)
 */
static VALUE
rb_digest_instance_update(VALUE self, VALUE str)
{
    rb_raise(rb_eRuntimeError, "%s does not implement update()", RSTRING_PTR(rb_inspect(self)));
}