package sql

import (
	"context"
)

type SummarizeGVKsRow struct {
	APIVersionCount int    `json:"c0"`
	APIVersion      string `json:"api_version"`
	KindCount       int    `json:"c1"`
	Kind            string `json:"kind"`
}

// SummarizeGVKs gives a high level rollup-style summary of watched resources across all clusters, counting
// by apiVersion and kind.
// For example:
// c0	api_version										c1	kind
// 614	"iam.cnrm.cloud.google.com/v1beta1"				532	"IAMPolicyMember"
// 614	"iam.cnrm.cloud.google.com/v1beta1"				41	"IAMPartialPolicy"
// 614	"iam.cnrm.cloud.google.com/v1beta1"				21	"IAMServiceAccount"
// 614	"iam.cnrm.cloud.google.com/v1beta1"				15	"IAMServiceAccountKey"
// 614	"iam.cnrm.cloud.google.com/v1beta1"				5	"IAMCustomRole"
// 230	"serviceusage.cnrm.cloud.google.com/v1beta1"	230	"Service"
// 127	"compute.cnrm.cloud.google.com/v1beta1"			97	"ComputeFirewall"
// shows the total count of all resources in group version, followed by a break down of which kinds contribute
// to that count.
func (db *DBHandle) SummarizeGVKs(ctx context.Context) ([]SummarizeGVKsRow, error) {
	query := `
SELECT max(c0) AS c0,
    max(api_version) AS api_version,
    max(c1) AS c1,
    kind
FROM (
        SELECT COUNT(*) over (PARTITION by api_version) AS c0,
            api_version,
            COUNT(*) over (PARTITION by kind) AS c1,
            kind
        FROM watched_resources
        ORDER BY c0 DESC,
            c1 DESC
    ) AS agg
GROUP BY kind
ORDER BY c0 DESC,
    c1 DESC
`

	rows, err := db.QueryContext(ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var results []SummarizeGVKsRow
	for rows.Next() {
		var result SummarizeGVKsRow
		if err := rows.Scan(&result.APIVersionCount, &result.APIVersion, &result.KindCount, &result.Kind); err != nil {
			return results, err
		}
		results = append(results, result)
	}

	if err := rows.Err(); err != nil {
		return results, err
	}

	return results, nil
}

type CountByGVKRows struct {
	Count      int    `json:"c"`
	APIVersion string `json:"api_version"`
	Kind       string `json:"kind"`
}

// CountByGVK gives a simple count summary of watched resources across all clusters, counting
// by apiVersion and kind. This is a more efficient, unsorted query suitable for gathering metrics data.
func (db *DBHandle) CountByGVK(ctx context.Context) ([]CountByGVKRows, error) {
	query := `
SELECT COUNT(*) as c, api_version, kind
FROM watched_resources
GROUP BY api_version, kind
`

	rows, err := db.QueryContext(ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var results []CountByGVKRows
	for rows.Next() {
		var result CountByGVKRows
		if err := rows.Scan(&result.Count, &result.APIVersion, &result.Kind); err != nil {
			return results, err
		}
		results = append(results, result)
	}

	if err := rows.Err(); err != nil {
		return results, err
	}

	return results, nil
}