package tsm1

import (
	"sort"

	"github.com/influxdata/influxdb/v2/tsdb"
)

{{range .}}
// merge combines the next set of blocks into merged blocks.
func (k *tsmBatchKeyIterator) merge{{.Name}}() {
	// No blocks left, or pending merged values, we're done
	if len(k.blocks) == 0 && len(k.merged) == 0 && k.merged{{.Name}}Values.Len() == 0 {
		return
	}

	sort.Stable(k.blocks)

	dedup := k.merged{{.Name}}Values.Len() != 0
	if len(k.blocks) > 0 && !dedup {
		// If we have more than one block or any partially tombstoned blocks, we many need to dedup
		dedup = len(k.blocks[0].tombstones) > 0 || k.blocks[0].partiallyRead()

		// Quickly scan each block to see if any overlap with the prior block, if they overlap then
		// we need to dedup as there may be duplicate points now
		for i := 1; !dedup && i < len(k.blocks); i++ {
			dedup = k.blocks[i].partiallyRead() ||
				k.blocks[i].overlapsTimeRange(k.blocks[i-1].minTime, k.blocks[i-1].maxTime) ||
				len(k.blocks[i].tombstones) > 0
		}

	}

	k.merged = k.combine{{.Name}}(dedup)
}

// combine returns a new set of blocks using the current blocks in the buffers.  If dedup
// is true, all the blocks will be decoded, dedup and sorted in in order.  If dedup is false,
// only blocks that are smaller than the chunk size will be decoded and combined.
func (k *tsmBatchKeyIterator) combine{{.Name}}(dedup bool) blocks {
	if dedup {
		for k.merged{{.Name}}Values.Len() < k.size && len(k.blocks) > 0 {
			for len(k.blocks) > 0 && k.blocks[0].read() {
				k.blocks = k.blocks[1:]
			}

			if len(k.blocks) == 0 {
				break
			}
			first := k.blocks[0]
			minTime := first.minTime
			maxTime := first.maxTime

			// Adjust the min time to the start of any overlapping blocks.
			for i := 0; i < len(k.blocks); i++ {
				if k.blocks[i].overlapsTimeRange(minTime, maxTime) && !k.blocks[i].read() {
					if k.blocks[i].minTime < minTime {
						minTime = k.blocks[i].minTime
					}
					if k.blocks[i].maxTime > minTime && k.blocks[i].maxTime < maxTime {
						maxTime = k.blocks[i].maxTime
					}
				}
			}

			// We have some overlapping blocks so decode all, append in order and then dedup
			for i := 0; i < len(k.blocks); i++ {
				if !k.blocks[i].overlapsTimeRange(minTime, maxTime) || k.blocks[i].read() {
					continue
				}

				var v tsdb.{{.Name}}Array
				var err error
				if err = Decode{{.Name}}ArrayBlock(k.blocks[i].b, &v); err != nil {
					k.handleDecodeError(err, "{{.name}}")
					return nil
				}

				// Invariant: v.MaxTime() == k.blocks[i].maxTime
				if k.blocks[i].maxTime != v.MaxTime() {
					if maxTime == k.blocks[i].maxTime {
						maxTime = v.MaxTime()
					}
					k.blocks[i].maxTime = v.MaxTime()
				}

				// Remove values we already read
				v.Exclude(k.blocks[i].readMin, k.blocks[i].readMax)

				// Filter out only the values for overlapping block
				v.Include(minTime, maxTime)
				if v.Len() > 0 {
					// Record that we read a subset of the block
					k.blocks[i].markRead(v.MinTime(), v.MaxTime())
				}

				// Apply each tombstone to the block
				for _, ts := range k.blocks[i].tombstones {
					v.Exclude(ts.Min, ts.Max)
				}

				k.merged{{.Name}}Values.Merge(&v)
			}
		}

		// Since we combined multiple blocks, we could have more values than we should put into
		// a single block.  We need to chunk them up into groups and re-encode them.
		return k.chunk{{.Name}}(nil)
	} 
	var i int

	for ; i < len(k.blocks); i++ {

		// skip this block if it's values were already read
		if k.blocks[i].read() {
			continue
		}

		// if this block is already full, just add it as is
		count, err := BlockCount(k.blocks[i].b)
		if err != nil {
		    k.AppendError(err)
		    continue
		}

		if count < k.size {
			break
		}

		k.merged = append(k.merged, k.blocks[i])
	}

	if k.fast {
		for i < len(k.blocks) {
			// skip this block if it's values were already read
			if k.blocks[i].read() {
				i++
				continue
			}

			k.merged = append(k.merged, k.blocks[i])
			i++
		}
	}

	// if we only have 1 blocks left, just append it as is and avoid decoding/recoding
	if i == len(k.blocks)-1 {
		if !k.blocks[i].read() {
			k.merged = append(k.merged, k.blocks[i])
		}
		i++
	}

	// The remaining blocks can be combined and we know that they do not overlap and
	// so we can just append each, sort and re-encode.
	for i < len(k.blocks) && k.merged{{.Name}}Values.Len() < k.size {
		if k.blocks[i].read() {
			i++
			continue
		}

		var v tsdb.{{.Name}}Array
		if err := Decode{{.Name}}ArrayBlock(k.blocks[i].b, &v); err != nil {
			k.handleDecodeError(err, "{{.name}}")
			return nil
		}

		// Invariant: v.MaxTime() == k.blocks[i].maxTime
		if k.blocks[i].maxTime != v.MaxTime() {
			k.blocks[i].maxTime = v.MaxTime()
		}

		// Apply each tombstone to the block
		for _, ts := range k.blocks[i].tombstones {
			v.Exclude(ts.Min, ts.Max)
		}

		k.blocks[i].markRead(k.blocks[i].minTime, k.blocks[i].maxTime)

		k.merged{{.Name}}Values.Merge(&v)
		i++
	}

	k.blocks = k.blocks[i:]

	return k.chunk{{.Name}}(k.merged)
}

func (k *tsmBatchKeyIterator) chunk{{.Name}}(dst blocks) blocks {
	if k.merged{{.Name}}Values.Len() > k.size {
		var values tsdb.{{.Name}}Array
		values.Timestamps = k.merged{{.Name}}Values.Timestamps[:k.size]
		minTime, maxTime := values.Timestamps[0], values.Timestamps[len(values.Timestamps)-1]
		values.Values = k.merged{{.Name}}Values.Values[:k.size]

		cb, err := Encode{{.Name}}ArrayBlock(&values, nil) // TODO(edd): pool this buffer
		if err != nil {
			k.handleEncodeError(err, "{{.name}}")
			return nil
		}

		dst = append(dst, &block{
			minTime: minTime,
			maxTime: maxTime,
			key:     k.key,
			b:       cb,
		})
		k.merged{{.Name}}Values.Timestamps = k.merged{{.Name}}Values.Timestamps[k.size:]
		k.merged{{.Name}}Values.Values = k.merged{{.Name}}Values.Values[k.size:]
		return dst
	}

	// Re-encode the remaining values into the last block
	if k.merged{{.Name}}Values.Len() > 0 {
		minTime, maxTime := k.merged{{.Name}}Values.Timestamps[0], k.merged{{.Name}}Values.Timestamps[len(k.merged{{.Name}}Values.Timestamps)-1]
		cb, err := Encode{{.Name}}ArrayBlock(k.merged{{.Name}}Values, nil) // TODO(edd): pool this buffer
		if err != nil {
			k.handleEncodeError(err, "{{.name}}")
			return nil
		}

		dst = append(dst, &block{
			minTime: minTime,
			maxTime: maxTime,
			key:     k.key,
			b:       cb,
		})
		k.merged{{.Name}}Values.Timestamps = k.merged{{.Name}}Values.Timestamps[:0]
		k.merged{{.Name}}Values.Values = k.merged{{.Name}}Values.Values[:0]
	}
	return dst
}


{{ end }}
