package elastic

import (
	"context"
	"fmt"
	"log"

	"elasticstream/opencdc"
)

func (c *Client) Read(context.Context) (*opencdc.Data, error) {
	log.Println(">>>> elastic.Read()")
	defer log.Println("<<<< elastic.Read()")

	if c == nil || c.ch == nil {
		return nil, fmt.Errorf("error source not opened for reading")
	}

	data, ok := <-c.ch
	if !ok {
		return nil, fmt.Errorf("error reading data from channel")
	}

	index := data.Header.Index
	if !ok {
		return nil, fmt.Errorf("error index not found in data header")
	}

	offset, ok := c.offsets[index]
	if !ok {
		return nil, fmt.Errorf("error offset index not found")
	}

	c.offsets[index] = offset + 1

	return &data, nil
}