/*
  Copyright 2011-2018 David Robillard <http://drobilla.net>

  Permission to use, copy, modify, and/or distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include "range.h"

#include "iter.h"
#include "model.h"
#include "world.h"

#include "zix/common.h"
#include "zix/digest.h"
#include "zix/hash.h"

#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

typedef enum { NAMED, ANON_S, ANON_O, LIST_S, LIST_O } NodeStyle;

static SerdStatus
write_range_statement(const SerdSink*      sink,
                      const SerdModel*     model,
                      ZixHash*             list_subjects,
                      unsigned             depth,
                      SerdStatementFlags   flags,
                      const SerdStatement* statement);

SerdRange*
serd_range_new(SerdIter* const begin, SerdIter* const end)
{
	SerdRange* range = (SerdRange*)malloc(sizeof(SerdRange));

	range->begin = begin;
	range->end   = end;

	return range;
}

SerdRange*
serd_range_copy(const SerdRange* range)
{
	SerdRange* copy = (SerdRange*)malloc(sizeof(SerdRange));

	memcpy(copy, range, sizeof(SerdRange));
	copy->begin = serd_iter_copy(range->begin);
	copy->end   = serd_iter_copy(range->end);

	return copy;
}

void
serd_range_free(SerdRange* range)
{
	serd_iter_free(range->begin);
	serd_iter_free(range->end);
	free(range);
}

const SerdStatement*
serd_range_front(const SerdRange* range)
{
	return serd_iter_get(range->begin);
}

bool
serd_range_equals(const SerdRange* lhs, const SerdRange* rhs)
{
	return (!lhs && !rhs) ||
	       (lhs && rhs && serd_iter_equals(lhs->begin, rhs->begin) &&
	        serd_iter_equals(lhs->end, rhs->end));
}

bool
serd_range_next(SerdRange* range)
{
	return serd_iter_next(range->begin);
}

bool
serd_range_empty(const SerdRange* range)
{
	return !range || serd_iter_equals(range->begin, range->end);
}

const SerdIter*
serd_range_cbegin(const SerdRange* range)
{
	return range->begin;
}

const SerdIter*
serd_range_cend(const SerdRange* range)
{
	return range->end;
}

SerdIter*
serd_range_begin(SerdRange* range)
{
	return range->begin;
}

SerdIter*
serd_range_end(SerdRange* range)
{
	return range->end;
}

static NodeStyle
get_node_style(const SerdModel* model, const SerdNode* node)
{
	if (serd_node_get_type(node) != SERD_BLANK) {
		return NAMED; // Non-blank node can't be anonymous
	}

	size_t     n_as_object = 0;
	SerdRange* range       = serd_model_range(model, NULL, NULL, node, NULL);
	for (; !serd_range_empty(range); serd_range_next(range), ++n_as_object) {
		if (n_as_object == 1) {
			return NAMED; // Blank node referred to several times
		}
	}

	if (serd_model_ask(model, node, model->world->rdf_first, NULL, NULL) &&
	    serd_model_ask(model, node, model->world->rdf_rest, NULL, NULL)) {
		return n_as_object == 0 ? LIST_S : LIST_O;
	}

	return n_as_object == 0 ? ANON_S : ANON_O;
}

static uint32_t
ptr_hash(const void* ptr)
{
	return zix_digest_add_ptr(zix_digest_start(), ptr);
}

static bool
ptr_equals(const void* a, const void* b)
{
	return *(const void* const*)a == *(const void* const*)b;
}

static SerdStatus
write_pretty_range(const SerdSink*          sink,
                   const unsigned           depth,
                   const SerdStatementFlags flags,
                   const SerdModel*         model,
                   SerdRange*               range)
{
	(void)flags;

	ZixHash* list_subjects = zix_hash_new(ptr_hash, ptr_equals, sizeof(void*));

	SerdStatus st = SERD_SUCCESS;
	for (; !st && !serd_range_empty(range); serd_range_next(range)) {
		st = write_range_statement(
		        sink, model, list_subjects, depth, 0, serd_range_front(range));
	}

	zix_hash_free(list_subjects);

	return st;
}

static SerdStatus
write_list(const SerdSink*    sink,
           const SerdModel*   model,
           ZixHash*           list_subjects,
           const unsigned     depth,
           SerdStatementFlags flags,
           const SerdNode*    object)
{
	SerdStatus       st    = SERD_SUCCESS;
	const SerdWorld* world = model->world;
	const SerdNode*  first = world->rdf_first;
	const SerdNode*  rest  = world->rdf_rest;
	const SerdNode*  nil   = world->rdf_nil;

	SerdIter* f = serd_model_find(model, object, first, NULL, NULL);
	while (!st && f && !serd_node_equals(object, nil)) {
		const SerdStatement* fs = serd_iter_get(f);

		st = write_range_statement(
		        sink, model, list_subjects, depth + 1, flags, fs);

		serd_iter_free(f);
		f     = NULL;
		flags = 0;
		if (st) {
			break;
		}

		SerdIter* const r = serd_model_find(model, object, rest, NULL, NULL);
		const SerdNode* next =
		        r ? serd_statement_get_object(serd_iter_get(r)) : NULL;

		f = next ? serd_model_find(model, next, first, NULL, NULL) : NULL;
		if (r && f) {
			// This and next node are good, write rdf:next statement
			st     = serd_sink_write_statement(sink, 0, serd_iter_get(r));
			object = next;
		} else {
			// Terminate malformed list
			st = serd_sink_write(
			        sink, 0, object, rest, nil, serd_statement_get_graph(fs));
			f = NULL;
		}

		serd_iter_free(r);
	}

	serd_iter_free(f);
	return st;
}

static SerdStatus
write_range_statement(const SerdSink*      sink,
                      const SerdModel*     model,
                      ZixHash*             list_subjects,
                      const unsigned       depth,
                      SerdStatementFlags   flags,
                      const SerdStatement* statement)
{
	const SerdNode* subject       = serd_statement_get_subject(statement);
	const NodeStyle subject_style = get_node_style(model, subject);

	if (depth == 0 && (subject_style == ANON_O || subject_style == LIST_O)) {
		return SERD_SUCCESS; // Skip subject that will be inlined somewhere
	} else if (subject_style == LIST_S && depth == 0 &&
	           (serd_node_equals(serd_statement_get_predicate(statement),
	                             model->world->rdf_first) ||
	            (serd_node_equals(serd_statement_get_predicate(statement),
	                              model->world->rdf_rest)))) {
		return SERD_SUCCESS;
	} else if (subject_style == ANON_S) {
		flags |= SERD_EMPTY_S; // Write anonymous subjects in "[] p o" style
	}

	const SerdNode* object       = serd_statement_get_object(statement);
	const NodeStyle object_style = get_node_style(model, object);
	SerdStatus      st           = SERD_SUCCESS;
	if (subject_style == LIST_S && depth == 0) {
		if (zix_hash_insert(list_subjects, &subject, NULL) !=
		    ZIX_STATUS_EXISTS) {
			st = write_list(sink,
			                model,
			                list_subjects,
			                depth + 1,
			                SERD_LIST_S,
			                subject);
		}
	}

	if (object_style == ANON_O) {
		flags |= SERD_ANON_O;

		SerdRange* range = serd_model_range(model, object, NULL, NULL, NULL);
		st = st ? st : serd_sink_write_statement(sink, flags, statement);
		st = st ? st : write_pretty_range(sink, depth + 1, 0, model, range);
		st = st ? st : serd_sink_write_end(sink, object);
		serd_range_free(range);

		return st;
	} else if (object_style == LIST_O) {
		flags |= SERD_LIST_O;
		st = st ? st : serd_sink_write_statement(sink, flags, statement);
		st = st ? st
		        : write_list(sink, model, list_subjects, depth + 1, 0, object);
		return st;
	}

	return serd_sink_write_statement(sink, flags, statement);
}

SerdStatus
serd_range_serialise(const SerdRange*             range,
                     const SerdSink*              sink,
                     const SerdSerialisationFlags flags)
{
	SerdStatus st = SERD_SUCCESS;
	if (serd_range_empty(range)) {
		return st;
	}

	SerdRange* const copy = serd_range_copy(range);
	if (flags & SERD_NO_INLINE_OBJECTS) {
		for (; !st && !serd_range_empty(copy); serd_range_next(copy)) {
			st = serd_sink_write_statement(sink, 0, serd_range_front(copy));
		}
	} else {
		st = write_pretty_range(sink, 0, 0, range->begin->model, copy);
	}

	serd_range_free(copy);
	return st;
}