package kafka

import (
	"bufio"
)

type offsetFetchRequestV1Topic struct {
	// Topic name
	Topic string

	// Partitions to fetch offsets
	Partitions []int32
}

func (t offsetFetchRequestV1Topic) size() int32 {
	return sizeofString(t.Topic) +
		sizeofInt32Array(t.Partitions)
}

func (t offsetFetchRequestV1Topic) writeTo(w *bufio.Writer) {
	writeString(w, t.Topic)
	writeInt32Array(w, t.Partitions)
}

type offsetFetchRequestV1 struct {
	// GroupID holds the unique group identifier
	GroupID string

	// Topics to fetch offsets.
	Topics []offsetFetchRequestV1Topic
}

func (t offsetFetchRequestV1) size() int32 {
	return sizeofString(t.GroupID) +
		sizeofArray(len(t.Topics), func(i int) int32 { return t.Topics[i].size() })
}

func (t offsetFetchRequestV1) writeTo(w *bufio.Writer) {
	writeString(w, t.GroupID)
	writeArray(w, len(t.Topics), func(i int) { t.Topics[i].writeTo(w) })
}

type offsetFetchResponseV1PartitionResponse struct {
	// Partition ID
	Partition int32

	// Offset of last committed message
	Offset int64

	// Metadata client wants to keep
	Metadata string

	// ErrorCode holds response error code
	ErrorCode int16
}

func (t offsetFetchResponseV1PartitionResponse) size() int32 {
	return sizeofInt32(t.Partition) +
		sizeofInt64(t.Offset) +
		sizeofString(t.Metadata) +
		sizeofInt16(t.ErrorCode)
}

func (t offsetFetchResponseV1PartitionResponse) writeTo(w *bufio.Writer) {
	writeInt32(w, t.Partition)
	writeInt64(w, t.Offset)
	writeString(w, t.Metadata)
	writeInt16(w, t.ErrorCode)
}

func (t *offsetFetchResponseV1PartitionResponse) readFrom(r *bufio.Reader, size int) (remain int, err error) {
	if remain, err = readInt32(r, size, &t.Partition); err != nil {
		return
	}
	if remain, err = readInt64(r, remain, &t.Offset); err != nil {
		return
	}
	if remain, err = readString(r, remain, &t.Metadata); err != nil {
		return
	}
	if remain, err = readInt16(r, remain, &t.ErrorCode); err != nil {
		return
	}
	return
}

type offsetFetchResponseV1Response struct {
	// Topic name
	Topic string

	// PartitionResponses holds offsets by partition
	PartitionResponses []offsetFetchResponseV1PartitionResponse
}

func (t offsetFetchResponseV1Response) size() int32 {
	return sizeofString(t.Topic) +
		sizeofArray(len(t.PartitionResponses), func(i int) int32 { return t.PartitionResponses[i].size() })
}

func (t offsetFetchResponseV1Response) writeTo(w *bufio.Writer) {
	writeString(w, t.Topic)
	writeArray(w, len(t.PartitionResponses), func(i int) { t.PartitionResponses[i].writeTo(w) })
}

func (t *offsetFetchResponseV1Response) readFrom(r *bufio.Reader, size int) (remain int, err error) {
	if remain, err = readString(r, size, &t.Topic); err != nil {
		return
	}

	fn := func(r *bufio.Reader, size int) (fnRemain int, fnErr error) {
		item := offsetFetchResponseV1PartitionResponse{}
		if fnRemain, fnErr = (&item).readFrom(r, size); err != nil {
			return
		}
		t.PartitionResponses = append(t.PartitionResponses, item)
		return
	}
	if remain, err = readArrayWith(r, remain, fn); err != nil {
		return
	}

	return
}

type offsetFetchResponseV1 struct {
	// Responses holds topic partition offsets
	Responses []offsetFetchResponseV1Response
}

func (t offsetFetchResponseV1) size() int32 {
	return sizeofArray(len(t.Responses), func(i int) int32 { return t.Responses[i].size() })
}

func (t offsetFetchResponseV1) writeTo(w *bufio.Writer) {
	writeArray(w, len(t.Responses), func(i int) { t.Responses[i].writeTo(w) })
}

func (t *offsetFetchResponseV1) readFrom(r *bufio.Reader, size int) (remain int, err error) {
	fn := func(r *bufio.Reader, withSize int) (fnRemain int, fnErr error) {
		item := offsetFetchResponseV1Response{}
		if fnRemain, fnErr = (&item).readFrom(r, withSize); fnErr != nil {
			return
		}
		t.Responses = append(t.Responses, item)
		return
	}
	if remain, err = readArrayWith(r, size, fn); err != nil {
		return
	}

	return
}

func findOffset(topic string, partition int32, response offsetFetchResponseV1) (int64, bool) {
	for _, r := range response.Responses {
		if r.Topic != topic {
			continue
		}

		for _, pr := range r.PartitionResponses {
			if pr.Partition == partition {
				return pr.Offset, true
			}
		}
	}

	return 0, false
}