package db

import (
	"database/sql"
	"time"
)

// PathTraceSessionRow is one persisted Path Tracer session blob.
type PathTraceSessionRow struct {
	ID        string
	CreatedAt time.Time
	Payload   []byte
}

// UpsertPathTraceSession stores or replaces a session JSON blob.
func (d *Database) UpsertPathTraceSession(id string, createdAt time.Time, payload []byte) error {
	_, err := d.Exec(
		`INSERT INTO pathtrace_sessions (id, created_at, payload)
		 VALUES (?, ?, ?)
		 ON CONFLICT(id) DO UPDATE SET created_at = excluded.created_at, payload = excluded.payload`,
		id, createdAt.UTC().Format(time.RFC3339Nano), payload,
	)
	return err
}

// ListPathTraceSessions returns all session rows ordered by age.
func (d *Database) ListPathTraceSessions() ([]PathTraceSessionRow, error) {
	rows, err := d.Query(`SELECT id, created_at, payload FROM pathtrace_sessions ORDER BY created_at ASC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []PathTraceSessionRow
	for rows.Next() {
		var row PathTraceSessionRow
		var created string
		if err := rows.Scan(&row.ID, &created, &row.Payload); err != nil {
			return nil, err
		}
		row.CreatedAt, _ = time.Parse(time.RFC3339Nano, created)
		if row.CreatedAt.IsZero() {
			row.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", created)
		}
		out = append(out, row)
	}
	return out, rows.Err()
}

// DeletePathTraceSession removes one session row.
func (d *Database) DeletePathTraceSession(id string) error {
	_, err := d.Exec(`DELETE FROM pathtrace_sessions WHERE id = ?`, id)
	return err
}

// DeleteExpiredPathTraceSessions removes rows older than cutoff.
func (d *Database) DeleteExpiredPathTraceSessions(cutoff time.Time) (int64, error) {
	res, err := d.Exec(`DELETE FROM pathtrace_sessions WHERE created_at < ?`, cutoff.UTC().Format(time.RFC3339Nano))
	if err != nil {
		return 0, err
	}
	return res.RowsAffected()
}

// PathTraceSessionCount returns how many session rows exist.
func (d *Database) PathTraceSessionCount() (int, error) {
	var n int
	err := d.QueryRow(`SELECT COUNT(*) FROM pathtrace_sessions`).Scan(&n)
	if err == sql.ErrNoRows {
		return 0, nil
	}
	return n, err
}