//  Copyright (c) 2014 Couchbase, Inc.
//  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 upside_down

import (
	"github.com/blevesearch/bleve/document"
)

type AnalysisResult struct {
	docID string
	rows  []UpsideDownCouchRow
}

type AnalysisWork struct {
	udc *UpsideDownCouch
	d   *document.Document
	rc  chan *AnalysisResult
}

type AnalysisQueue struct {
	queue chan *AnalysisWork
	done  chan struct{}
}

func (q *AnalysisQueue) Queue(work *AnalysisWork) {
	q.queue <- work
}

func (q *AnalysisQueue) Close() {
	close(q.done)
}

func NewAnalysisQueue(numWorkers int) *AnalysisQueue {
	rv := AnalysisQueue{
		queue: make(chan *AnalysisWork),
		done:  make(chan struct{}),
	}
	for i := 0; i < numWorkers; i++ {
		go AnalysisWorker(rv)
	}
	return &rv
}

func AnalysisWorker(q AnalysisQueue) {
	// read work off the queue
	for {
		select {
		case <-q.done:
			return
		case w := <-q.queue:

			rv := &AnalysisResult{
				docID: w.d.ID,
				rows:  make([]UpsideDownCouchRow, 0, 100),
			}

			// track our back index entries
			backIndexTermEntries := make([]*BackIndexTermEntry, 0)
			backIndexStoredEntries := make([]*BackIndexStoreEntry, 0)

			for _, field := range w.d.Fields {
				fieldIndex, newFieldRow := w.udc.fieldIndexCache.FieldIndex(field.Name())
				if newFieldRow != nil {
					rv.rows = append(rv.rows, newFieldRow)
				}

				if field.Options().IsIndexed() {

					fieldLength, tokenFreqs := field.Analyze()

					// see if any of the composite fields need this
					for _, compositeField := range w.d.CompositeFields {
						compositeField.Compose(field.Name(), fieldLength, tokenFreqs)
					}

					// encode this field
					indexRows, indexBackIndexTermEntries := w.udc.indexField(w.d.ID, field, fieldIndex, fieldLength, tokenFreqs)
					rv.rows = append(rv.rows, indexRows...)
					backIndexTermEntries = append(backIndexTermEntries, indexBackIndexTermEntries...)
				}

				if field.Options().IsStored() {
					storeRows, indexBackIndexStoreEntries := w.udc.storeField(w.d.ID, field, fieldIndex)
					rv.rows = append(rv.rows, storeRows...)
					backIndexStoredEntries = append(backIndexStoredEntries, indexBackIndexStoreEntries...)
				}

			}

			// now index the composite fields
			for _, compositeField := range w.d.CompositeFields {
				fieldIndex, newFieldRow := w.udc.fieldIndexCache.FieldIndex(compositeField.Name())
				if newFieldRow != nil {
					rv.rows = append(rv.rows, newFieldRow)
				}
				if compositeField.Options().IsIndexed() {
					fieldLength, tokenFreqs := compositeField.Analyze()
					// encode this field
					indexRows, indexBackIndexTermEntries := w.udc.indexField(w.d.ID, compositeField, fieldIndex, fieldLength, tokenFreqs)
					rv.rows = append(rv.rows, indexRows...)
					backIndexTermEntries = append(backIndexTermEntries, indexBackIndexTermEntries...)
				}
			}

			// build the back index row
			backIndexRow := NewBackIndexRow(w.d.ID, backIndexTermEntries, backIndexStoredEntries)
			rv.rows = append(rv.rows, backIndexRow)

			w.rc <- rv

		}

	}
}
