package sqlite

import (
	"database/sql"
	"fmt"
)

// backfillTicketKeys assigns project codes and sequential ticket keys for rows
// that predate migration 005. Safe to run repeatedly (no-ops when already set).
func (db *DB) backfillTicketKeys() error {
	if err := db.backfillProjectCodes(); err != nil {
		return err
	}
	return db.backfillTicketNumbers()
}

func (db *DB) backfillProjectCodes() error {
	rows, err := db.SQL.Query(`SELECT id, name, code FROM projects`)
	if err != nil {
		return fmt.Errorf("backfill codes: list: %w", err)
	}
	defer rows.Close()

	type row struct {
		id, name, code string
	}
	var all []row
	used := map[string]bool{}
	for rows.Next() {
		var r row
		if err := rows.Scan(&r.id, &r.name, &r.code); err != nil {
			return err
		}
		all = append(all, r)
		if r.code != "" {
			used[r.code] = true
		}
	}
	if err := rows.Err(); err != nil {
		return err
	}

	for _, r := range all {
		if r.code != "" {
			continue
		}
		code := nextUniqueCode(r.name, used)
		used[code] = true
		if _, err := db.SQL.Exec(`UPDATE projects SET code = ? WHERE id = ?`, code, r.id); err != nil {
			return fmt.Errorf("backfill code %s: %w", r.id, err)
		}
	}
	return nil
}

func (db *DB) backfillTicketNumbers() error {
	type proj struct {
		id, code string
		seq      int
	}
	var projects []proj
	{
		projRows, err := db.SQL.Query(`SELECT id, code, ticket_seq FROM projects`)
		if err != nil {
			return fmt.Errorf("backfill tickets: projects: %w", err)
		}
		for projRows.Next() {
			var p proj
			if err := projRows.Scan(&p.id, &p.code, &p.seq); err != nil {
				projRows.Close()
				return err
			}
			projects = append(projects, p)
		}
		err = projRows.Err()
		projRows.Close()
		if err != nil {
			return err
		}
	}

	for _, p := range projects {
		type trow struct {
			id, key string
			number  sql.NullInt64
		}
		var tickets []trow
		{
			tRows, err := db.SQL.Query(`
				SELECT id, number, key FROM tickets
				WHERE project_id = ?
				ORDER BY created_at ASC, id ASC`, p.id)
			if err != nil {
				return err
			}
			for tRows.Next() {
				var tr trow
				if err := tRows.Scan(&tr.id, &tr.number, &tr.key); err != nil {
					tRows.Close()
					return err
				}
				tickets = append(tickets, tr)
			}
			err = tRows.Err()
			tRows.Close()
			if err != nil {
				return err
			}
		}
		seq := p.seq
		for _, tr := range tickets {
			if tr.number.Valid && tr.key != "" {
				if int(tr.number.Int64) > seq {
					seq = int(tr.number.Int64)
				}
				continue
			}
			seq++
			newKey := fmt.Sprintf("%s-%d", p.code, seq)
			if _, err := db.SQL.Exec(`UPDATE tickets SET number = ?, key = ? WHERE id = ?`, seq, newKey, tr.id); err != nil {
				return fmt.Errorf("backfill ticket %s: %w", tr.id, err)
			}
		}
		if seq != p.seq {
			if _, err := db.SQL.Exec(`UPDATE projects SET ticket_seq = ? WHERE id = ?`, seq, p.id); err != nil {
				return err
			}
		}
	}
	return nil
}