package store

import (
	"database/sql"
	"fmt"
	"time"

	"github.com/local-mcp/local-mcp-go/internal/models"
)

// AgentStore records and retrieves agent connectivity data.
type AgentStore struct {
	db *sql.DB
}

// NewAgentStore creates an AgentStore backed by db.
func NewAgentStore(db *sql.DB) *AgentStore {
	return &AgentStore{db: db}
}

// Record upserts agent activity for agentID with the given result type.
func (s *AgentStore) Record(agentID, resultType string) error {
	now := time.Now().UTC().Format(time.RFC3339Nano)
	_, err := s.db.Exec(`
		INSERT INTO agent_activity (agent_id, last_seen_at, last_fetch_at, last_result_type)
		VALUES (?, ?, ?, ?)
		ON CONFLICT(agent_id) DO UPDATE SET
		    last_seen_at     = excluded.last_seen_at,
		    last_fetch_at    = excluded.last_fetch_at,
		    last_result_type = excluded.last_result_type`,
		agentID, now, now, resultType)
	return err
}

// Latest returns the most recently active agent, or nil if no agent has ever
// called get_user_request.
func (s *AgentStore) Latest() (*models.AgentActivity, error) {
	row := s.db.QueryRow(`
		SELECT agent_id, last_seen_at, last_fetch_at, last_result_type
		FROM agent_activity
		ORDER BY last_seen_at DESC
		LIMIT 1`)

	var a models.AgentActivity
	var seenStr, fetchStr string
	err := row.Scan(&a.AgentID, &seenStr, &fetchStr, &a.LastResultType)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("latest agent: %w", err)
	}

	a.LastSeenAt, _ = time.Parse(time.RFC3339Nano, seenStr)
	a.LastFetchAt, _ = time.Parse(time.RFC3339Nano, fetchStr)
	return &a, nil
}