// Copyright 2014 The Cayley Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package writer

import (
	"time"

	"github.com/google/cayley/graph"
	"github.com/google/cayley/quad"
)

func init() {
	graph.RegisterWriter("single", NewSingleReplication)
}

type Single struct {
	currentID  graph.PrimaryKey
	qs         graph.QuadStore
	ignoreOpts graph.IgnoreOpts
}

func NewSingleReplication(qs graph.QuadStore, opts graph.Options) (graph.QuadWriter, error) {
	var (
		ignoreMissing   bool
		ignoreDuplicate bool
		err             error
	)

	if *graph.IgnoreMissing {
		ignoreMissing = true
	} else {
		ignoreMissing, _, err = opts.BoolKey("ignore_missing")
		if err != nil {
			return nil, err
		}
	}

	if *graph.IgnoreDup {
		ignoreDuplicate = true
	} else {
		ignoreDuplicate, _, err = opts.BoolKey("ignore_duplicate")
		if err != nil {
			return nil, err
		}
	}

	return &Single{
		currentID: qs.Horizon(),
		qs:        qs,
		ignoreOpts: graph.IgnoreOpts{
			IgnoreDup:     ignoreDuplicate,
			IgnoreMissing: ignoreMissing,
		},
	}, nil
}

func (s *Single) AddQuad(q quad.Quad) error {
	deltas := make([]graph.Delta, 1)
	deltas[0] = graph.Delta{
		ID:        s.currentID.Next(),
		Quad:      q,
		Action:    graph.Add,
		Timestamp: time.Now(),
	}
	return s.qs.ApplyDeltas(deltas, s.ignoreOpts)
}

func (s *Single) AddQuadSet(set []quad.Quad) error {
	deltas := make([]graph.Delta, len(set))
	for i, q := range set {
		deltas[i] = graph.Delta{
			ID:        s.currentID.Next(),
			Quad:      q,
			Action:    graph.Add,
			Timestamp: time.Now(),
		}
	}

	return s.qs.ApplyDeltas(deltas, s.ignoreOpts)
}

func (s *Single) RemoveQuad(q quad.Quad) error {
	deltas := make([]graph.Delta, 1)
	deltas[0] = graph.Delta{
		ID:        s.currentID.Next(),
		Quad:      q,
		Action:    graph.Delete,
		Timestamp: time.Now(),
	}
	return s.qs.ApplyDeltas(deltas, s.ignoreOpts)
}

func (s *Single) Close() error {
	// Nothing to clean up locally.
	return nil
}

func (s *Single) ApplyTransaction(t *graph.Transaction) error {
	ts := time.Now()
	for i := 0; i < len(t.Deltas); i++ {
		t.Deltas[i].ID = s.currentID.Next()
		t.Deltas[i].Timestamp = ts
	}
	return s.qs.ApplyDeltas(t.Deltas, s.ignoreOpts)
}
