#include <psych.h>

#if !defined(RARRAY_CONST_PTR)
#define RARRAY_CONST_PTR(s) (const VALUE *)RARRAY_PTR(s)
#endif
#if !defined(RARRAY_AREF)
#define RARRAY_AREF(a, i) RARRAY_CONST_PTR(a)[i]
#endif

VALUE cPsychEmitter;
static ID id_io;
static ID id_write;
static ID id_line_width;
static ID id_indentation;
static ID id_canonical;

static void emit(yaml_emitter_t * emitter, yaml_event_t * event)
{
    if(!yaml_emitter_emit(emitter, event))
        rb_raise(rb_eRuntimeError, "%s", emitter->problem);
}

static int writer(void *ctx, unsigned char *buffer, size_t size)
{
    VALUE self = (VALUE)ctx, io = rb_attr_get(self, id_io);
    VALUE str = rb_enc_str_new((const char *)buffer, (long)size, rb_utf8_encoding());
    VALUE wrote = rb_funcall(io, id_write, 1, str);
    return (int)NUM2INT(wrote);
}

static void dealloc(void * ptr)
{
    yaml_emitter_t * emitter;

    emitter = (yaml_emitter_t *)ptr;
    yaml_emitter_delete(emitter);
    xfree(emitter);
}

#if 0
static size_t memsize(const void *ptr)
{
    const yaml_emitter_t *emitter = ptr;
    /* TODO: calculate emitter's size */
    return 0;
}
#endif

static const rb_data_type_t psych_emitter_type = {
    "Psych/emitter",
    {0, dealloc, 0,},
    0, 0,
#ifdef RUBY_TYPED_FREE_IMMEDIATELY
    RUBY_TYPED_FREE_IMMEDIATELY,
#endif
};

static VALUE allocate(VALUE klass)
{
    yaml_emitter_t * emitter;
    VALUE obj = TypedData_Make_Struct(klass, yaml_emitter_t, &psych_emitter_type, emitter);

    yaml_emitter_initialize(emitter);
    yaml_emitter_set_unicode(emitter, 1);
    yaml_emitter_set_indent(emitter, 2);

    return obj;
}

/* call-seq: Psych::Emitter.new(io, options = Psych::Emitter::OPTIONS)
 *
 * Create a new Psych::Emitter that writes to +io+.
 */
static VALUE initialize(int argc, VALUE *argv, VALUE self)
{
    yaml_emitter_t * emitter;
    VALUE io, options;
    VALUE line_width;
    VALUE indent;
    VALUE canonical;

    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    if (rb_scan_args(argc, argv, "11", &io, &options) == 2) {
        line_width = rb_funcall(options, id_line_width, 0);
        indent     = rb_funcall(options, id_indentation, 0);
        canonical  = rb_funcall(options, id_canonical, 0);

        yaml_emitter_set_width(emitter, NUM2INT(line_width));
        yaml_emitter_set_indent(emitter, NUM2INT(indent));
        yaml_emitter_set_canonical(emitter, Qtrue == canonical ? 1 : 0);
    }

    rb_ivar_set(self, id_io, io);
    yaml_emitter_set_output(emitter, writer, (void *)self);

    return self;
}

/* call-seq: emitter.start_stream(encoding)
 *
 * Start a stream emission with +encoding+
 *
 * See Psych::Handler#start_stream
 */
static VALUE start_stream(VALUE self, VALUE encoding)
{
    yaml_emitter_t * emitter;
    yaml_event_t event;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);
    Check_Type(encoding, T_FIXNUM);

    yaml_stream_start_event_initialize(&event, (yaml_encoding_t)NUM2INT(encoding));

    emit(emitter, &event);

    return self;
}

/* call-seq: emitter.end_stream
 *
 * End a stream emission
 *
 * See Psych::Handler#end_stream
 */
static VALUE end_stream(VALUE self)
{
    yaml_emitter_t * emitter;
    yaml_event_t event;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    yaml_stream_end_event_initialize(&event);

    emit(emitter, &event);

    return self;
}

struct start_document_data {
    VALUE self;
    VALUE version;
    VALUE tags;
    VALUE imp;

    yaml_tag_directive_t * head;
};

static VALUE start_document_try(VALUE d)
{
    struct start_document_data * data = (struct start_document_data *)d;
    VALUE self = data->self;
    VALUE version = data->version;
    VALUE tags = data->tags;
    VALUE imp = data->imp;

    yaml_emitter_t * emitter;
    yaml_tag_directive_t * tail = NULL;
    yaml_event_t event;
    yaml_version_directive_t version_directive;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    Check_Type(version, T_ARRAY);

    if(RARRAY_LEN(version) > 0) {
        VALUE major = rb_ary_entry(version, (long)0);
        VALUE minor = rb_ary_entry(version, (long)1);

        version_directive.major = NUM2INT(major);
        version_directive.minor = NUM2INT(minor);
    }

    if(RTEST(tags)) {
        long i = 0;
        long len;
        rb_encoding * encoding = rb_utf8_encoding();

        Check_Type(tags, T_ARRAY);

        len = RARRAY_LEN(tags);
        data->head = xcalloc((size_t)len, sizeof(yaml_tag_directive_t));
        tail = data->head;

        for(i = 0; i < len && i < RARRAY_LEN(tags); i++) {
            VALUE tuple = RARRAY_AREF(tags, i);
            VALUE name;
            VALUE value;

            Check_Type(tuple, T_ARRAY);

            if(RARRAY_LEN(tuple) < 2) {
                rb_raise(rb_eRuntimeError, "tag tuple must be of length 2");
            }

            name  = RARRAY_AREF(tuple, 0);
            value = RARRAY_AREF(tuple, 1);
            StringValue(name);
            StringValue(value);
            name = rb_str_export_to_enc(name, encoding);
            value = rb_str_export_to_enc(value, encoding);

            tail->handle = (yaml_char_t *)StringValueCStr(name);
            tail->prefix = (yaml_char_t *)StringValueCStr(value);

            tail++;
        }
    }

    yaml_document_start_event_initialize(
            &event,
            (RARRAY_LEN(version) > 0) ? &version_directive : NULL,
            data->head,
            tail,
            imp ? 1 : 0
            );

    emit(emitter, &event);

    return self;
}

static VALUE start_document_ensure(VALUE d)
{
    struct start_document_data * data = (struct start_document_data *)d;

    xfree(data->head);

    return Qnil;
}

/* call-seq: emitter.start_document(version, tags, implicit)
 *
 * Start a document emission with YAML +version+, +tags+, and an +implicit+
 * start.
 *
 * See Psych::Handler#start_document
 */
static VALUE start_document(VALUE self, VALUE version, VALUE tags, VALUE imp)
{
    struct start_document_data data = {
        .self = self,
        .version = version,
        .tags = tags,
        .imp = imp,

        .head = NULL,
    };

    return rb_ensure(start_document_try, (VALUE)&data, start_document_ensure, (VALUE)&data);
}

/* call-seq: emitter.end_document(implicit)
 *
 * End a document emission with an +implicit+ ending.
 *
 * See Psych::Handler#end_document
 */
static VALUE end_document(VALUE self, VALUE imp)
{
    yaml_emitter_t * emitter;
    yaml_event_t event;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    yaml_document_end_event_initialize(&event, imp ? 1 : 0);

    emit(emitter, &event);

    return self;
}

/* call-seq: emitter.scalar(value, anchor, tag, plain, quoted, style)
 *
 * Emit a scalar with +value+, +anchor+, +tag+, and a +plain+ or +quoted+
 * string type with +style+.
 *
 * See Psych::Handler#scalar
 */
static VALUE scalar(
        VALUE self,
        VALUE value,
        VALUE anchor,
        VALUE tag,
        VALUE plain,
        VALUE quoted,
        VALUE style
        ) {
    yaml_emitter_t * emitter;
    yaml_event_t event;
    rb_encoding *encoding;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    Check_Type(value, T_STRING);

    encoding = rb_utf8_encoding();

    value = rb_str_export_to_enc(value, encoding);

    if(!NIL_P(anchor)) {
        Check_Type(anchor, T_STRING);
        anchor = rb_str_export_to_enc(anchor, encoding);
    }

    if(!NIL_P(tag)) {
        Check_Type(tag, T_STRING);
        tag = rb_str_export_to_enc(tag, encoding);
    }

    const char *value_ptr = StringValuePtr(value);
    yaml_scalar_event_initialize(
            &event,
            (yaml_char_t *)(NIL_P(anchor) ? NULL : StringValueCStr(anchor)),
            (yaml_char_t *)(NIL_P(tag) ? NULL : StringValueCStr(tag)),
            (yaml_char_t*)value_ptr,
            (int)RSTRING_LEN(value),
            plain ? 1 : 0,
            quoted ? 1 : 0,
            (yaml_scalar_style_t)NUM2INT(style)
            );

    emit(emitter, &event);

    return self;
}

/* call-seq: emitter.start_sequence(anchor, tag, implicit, style)
 *
 * Start emitting a sequence with +anchor+, a +tag+, +implicit+ sequence
 * start and end, along with +style+.
 *
 * See Psych::Handler#start_sequence
 */
static VALUE start_sequence(
        VALUE self,
        VALUE anchor,
        VALUE tag,
        VALUE implicit,
        VALUE style
        ) {
    yaml_emitter_t * emitter;
    yaml_event_t event;

    rb_encoding * encoding = rb_utf8_encoding();

    if(!NIL_P(anchor)) {
        Check_Type(anchor, T_STRING);
        anchor = rb_str_export_to_enc(anchor, encoding);
    }

    if(!NIL_P(tag)) {
        Check_Type(tag, T_STRING);
        tag = rb_str_export_to_enc(tag, encoding);
    }

    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    yaml_sequence_start_event_initialize(
            &event,
            (yaml_char_t *)(NIL_P(anchor) ? NULL : StringValueCStr(anchor)),
            (yaml_char_t *)(NIL_P(tag) ? NULL : StringValueCStr(tag)),
            implicit ? 1 : 0,
            (yaml_sequence_style_t)NUM2INT(style)
            );

    emit(emitter, &event);

    return self;
}

/* call-seq: emitter.end_sequence
 *
 * End sequence emission.
 *
 * See Psych::Handler#end_sequence
 */
static VALUE end_sequence(VALUE self)
{
    yaml_emitter_t * emitter;
    yaml_event_t event;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    yaml_sequence_end_event_initialize(&event);

    emit(emitter, &event);

    return self;
}

/* call-seq: emitter.start_mapping(anchor, tag, implicit, style)
 *
 * Start emitting a YAML map with +anchor+, +tag+, an +implicit+ start
 * and end, and +style+.
 *
 * See Psych::Handler#start_mapping
 */
static VALUE start_mapping(
        VALUE self,
        VALUE anchor,
        VALUE tag,
        VALUE implicit,
        VALUE style
        ) {
    yaml_emitter_t * emitter;
    yaml_event_t event;
    rb_encoding *encoding;

    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    encoding = rb_utf8_encoding();

    if(!NIL_P(anchor)) {
        Check_Type(anchor, T_STRING);
        anchor = rb_str_export_to_enc(anchor, encoding);
    }

    if(!NIL_P(tag)) {
        Check_Type(tag, T_STRING);
        tag = rb_str_export_to_enc(tag, encoding);
    }

    yaml_mapping_start_event_initialize(
            &event,
            (yaml_char_t *)(NIL_P(anchor) ? NULL : StringValueCStr(anchor)),
            (yaml_char_t *)(NIL_P(tag) ? NULL : StringValueCStr(tag)),
            implicit ? 1 : 0,
            (yaml_mapping_style_t)NUM2INT(style)
            );

    emit(emitter, &event);

    return self;
}

/* call-seq: emitter.end_mapping
 *
 * Emit the end of a mapping.
 *
 * See Psych::Handler#end_mapping
 */
static VALUE end_mapping(VALUE self)
{
    yaml_emitter_t * emitter;
    yaml_event_t event;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    yaml_mapping_end_event_initialize(&event);

    emit(emitter, &event);

    return self;
}

/* call-seq: emitter.alias(anchor)
 *
 * Emit an alias with +anchor+.
 *
 * See Psych::Handler#alias
 */
static VALUE alias(VALUE self, VALUE anchor)
{
    yaml_emitter_t * emitter;
    yaml_event_t event;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    if(!NIL_P(anchor)) {
        Check_Type(anchor, T_STRING);
        anchor = rb_str_export_to_enc(anchor, rb_utf8_encoding());
    }

    yaml_alias_event_initialize(
            &event,
            (yaml_char_t *)(NIL_P(anchor) ? NULL : StringValueCStr(anchor))
            );

    emit(emitter, &event);

    return self;
}

/* call-seq: emitter.canonical = true
 *
 * Set the output style to canonical, or not.
 */
static VALUE set_canonical(VALUE self, VALUE style)
{
    yaml_emitter_t * emitter;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    yaml_emitter_set_canonical(emitter, Qtrue == style ? 1 : 0);

    return style;
}

/* call-seq: emitter.canonical
 *
 * Get the output style, canonical or not.
 */
static VALUE canonical(VALUE self)
{
    yaml_emitter_t * emitter;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    return (emitter->canonical == 0) ? Qfalse : Qtrue;
}

/* call-seq: emitter.indentation = level
 *
 * Set the indentation level to +level+.  The level must be less than 10 and
 * greater than 1.
 */
static VALUE set_indentation(VALUE self, VALUE level)
{
    yaml_emitter_t * emitter;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    yaml_emitter_set_indent(emitter, NUM2INT(level));

    return level;
}

/* call-seq: emitter.indentation
 *
 * Get the indentation level.
 */
static VALUE indentation(VALUE self)
{
    yaml_emitter_t * emitter;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    return INT2NUM(emitter->best_indent);
}

/* call-seq: emitter.line_width
 *
 * Get the preferred line width.
 */
static VALUE line_width(VALUE self)
{
    yaml_emitter_t * emitter;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    return INT2NUM(emitter->best_width);
}

/* call-seq: emitter.line_width = width
 *
 * Set the preferred line with to +width+.
 */
static VALUE set_line_width(VALUE self, VALUE width)
{
    yaml_emitter_t * emitter;
    TypedData_Get_Struct(self, yaml_emitter_t, &psych_emitter_type, emitter);

    yaml_emitter_set_width(emitter, NUM2INT(width));

    return width;
}

void Init_psych_emitter(void)
{
#undef rb_intern
    VALUE psych     = rb_define_module("Psych");
    VALUE handler   = rb_define_class_under(psych, "Handler", rb_cObject);
    cPsychEmitter   = rb_define_class_under(psych, "Emitter", handler);

    rb_define_alloc_func(cPsychEmitter, allocate);

    rb_define_method(cPsychEmitter, "initialize", initialize, -1);
    rb_define_method(cPsychEmitter, "start_stream", start_stream, 1);
    rb_define_method(cPsychEmitter, "end_stream", end_stream, 0);
    rb_define_method(cPsychEmitter, "start_document", start_document, 3);
    rb_define_method(cPsychEmitter, "end_document", end_document, 1);
    rb_define_method(cPsychEmitter, "scalar", scalar, 6);
    rb_define_method(cPsychEmitter, "start_sequence", start_sequence, 4);
    rb_define_method(cPsychEmitter, "end_sequence", end_sequence, 0);
    rb_define_method(cPsychEmitter, "start_mapping", start_mapping, 4);
    rb_define_method(cPsychEmitter, "end_mapping", end_mapping, 0);
    rb_define_method(cPsychEmitter, "alias", alias, 1);
    rb_define_method(cPsychEmitter, "canonical", canonical, 0);
    rb_define_method(cPsychEmitter, "canonical=", set_canonical, 1);
    rb_define_method(cPsychEmitter, "indentation", indentation, 0);
    rb_define_method(cPsychEmitter, "indentation=", set_indentation, 1);
    rb_define_method(cPsychEmitter, "line_width", line_width, 0);
    rb_define_method(cPsychEmitter, "line_width=", set_line_width, 1);

    id_io          = rb_intern("io");
    id_write       = rb_intern("write");
    id_line_width  = rb_intern("line_width");
    id_indentation = rb_intern("indentation");
    id_canonical   = rb_intern("canonical");
}
