package migrations

import (
	"log"

	"github.com/jmoiron/sqlx"
	"github.com/knadh/koanf/v2"
	"github.com/knadh/stuffbin"
)

// V5_0_0 performs the DB migrations.
func V5_0_0(db *sqlx.DB, fs stuffbin.FileSystem, ko *koanf.Koanf, lo *log.Logger) error {
	lo.Println("IMPORTANT: this upgrade might take a while if you have a large database. Please be patient ...")
	if _, err := db.Exec(`
		-- Create a new temp materialized view with the fixed query (removing COUNT(*) that returns 1 for NULLs) 
		CREATE MATERIALIZED VIEW IF NOT EXISTS mat_list_subscriber_stats_v5_0_0 AS
		SELECT NOW() AS updated_at, lists.id AS list_id, subscriber_lists.status, COUNT(subscriber_lists.status) AS subscriber_count FROM lists
		LEFT JOIN subscriber_lists ON (subscriber_lists.list_id = lists.id)
		GROUP BY lists.id, subscriber_lists.status
		UNION ALL
		SELECT NOW() AS updated_at, 0 AS list_id, NULL AS status, COUNT(id) AS subscriber_count FROM subscribers;
	
		-- Drop the old view and index.
		DROP INDEX IF EXISTS mat_list_subscriber_stats_idx;
		DROP MATERIALIZED VIEW IF EXISTS mat_list_subscriber_stats;
		
		-- Rename the temp view and create an index.
		ALTER MATERIALIZED VIEW mat_list_subscriber_stats_v5_0_0 RENAME TO mat_list_subscriber_stats;
		CREATE UNIQUE INDEX IF NOT EXISTS mat_list_subscriber_stats_idx ON mat_list_subscriber_stats (list_id, status);
	`); err != nil {
		return err
	}

	return nil
}