package emr

import (
	"context"
	"fmt"
	"strings"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/service/emr"
	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
	"github.com/hashicorp/terraform-provider-aws/internal/conns"
)

func DataSourceReleaseLabels() *schema.Resource {
	return &schema.Resource{
		ReadWithoutTimeout: dataSourceReleaseLabelsRead,

		Schema: map[string]*schema.Schema{
			"filters": {
				Type:     schema.TypeList,
				MaxItems: 1,
				Optional: true,
				Elem: &schema.Resource{
					Schema: map[string]*schema.Schema{
						"application": {
							Type:     schema.TypeString,
							Optional: true,
						},
						"prefix": {
							Type:     schema.TypeString,
							Optional: true,
						},
					},
				},
			},
			"release_labels": {
				Type:     schema.TypeList,
				Elem:     &schema.Schema{Type: schema.TypeString},
				Computed: true,
			},
		},
	}
}

func dataSourceReleaseLabelsRead(ctx context.Context, d *schema.ResourceData, meta interface{}) diag.Diagnostics {
	conn := meta.(*conns.AWSClient).EMRConn()

	input := &emr.ListReleaseLabelsInput{}

	if v, ok := d.GetOk("filters"); ok && len(v.([]interface{})) > 0 {
		input.Filters = expandReleaseLabelsFilters(v.([]interface{}))
	}

	output, err := findReleaseLabels(conn, input)

	if err != nil {
		return diag.FromErr(fmt.Errorf("error reading EMR Release Labels: %w", err))
	}

	releaseLabels := aws.StringValueSlice(output)

	if len(releaseLabels) == 0 {
		d.SetId(",")
	} else {
		d.SetId(strings.Join(releaseLabels, ","))
	}
	d.Set("release_labels", releaseLabels)

	return nil
}

func expandReleaseLabelsFilters(filters []interface{}) *emr.ReleaseLabelFilter {
	if len(filters) == 0 || filters[0] == nil {
		return nil
	}

	m := filters[0].(map[string]interface{})
	app := &emr.ReleaseLabelFilter{}

	if v, ok := m["application"].(string); ok && v != "" {
		app.Application = aws.String(v)
	}

	if v, ok := m["prefix"].(string); ok && v != "" {
		app.Prefix = aws.String(v)
	}

	return app
}

func findReleaseLabels(conn *emr.EMR, input *emr.ListReleaseLabelsInput) ([]*string, error) {
	var output []*string

	err := conn.ListReleaseLabelsPages(input, func(page *emr.ListReleaseLabelsOutput, lastPage bool) bool {
		if page == nil {
			return !lastPage
		}
		for _, v := range page.ReleaseLabels {
			if v != nil {
				output = append(output, v)
			}
		}

		return !lastPage
	})

	if err != nil {
		return nil, err
	}

	return output, nil
}
