// Package stats computes dashboard/API statistics from request logs and
// the live runtime snapshot.
package stats

import (
	"database/sql"
	"time"

	"github.com/owen/vibeproxy/internal/database"
	"github.com/owen/vibeproxy/internal/models"
	"github.com/owen/vibeproxy/internal/runtime"
)

type Dashboard struct {
	ActiveProxyHosts   int                    `json:"active_proxy_hosts"`
	ActiveTCPStreams   int                    `json:"active_tcp_streams"`
	ActiveUDPStreams   int                    `json:"active_udp_streams"`
	RequestsLastHour   int                    `json:"requests_last_hour"`
	RequestsPerSecond  float64                `json:"requests_per_second"`
	TotalRequestsToday int                    `json:"total_requests_today"`
	StatusBreakdown    []database.StatusCount `json:"status_breakdown"`
	BackendHealth      []BackendHealthEntry   `json:"backend_health"`
	CertsExpiringSoon  []models.Certificate   `json:"certs_expiring_soon"`
	TopHosts           []database.HostCount   `json:"top_hosts"`
	TopClients         []database.HostCount   `json:"top_clients"`
	RecentErrors       []models.RequestLog    `json:"recent_errors"`
}

type BackendHealthEntry struct {
	ProxyHost string `json:"proxy_host"`
	Backend   string `json:"backend"`
	Healthy   bool   `json:"healthy"`
}

func Compute(db *sql.DB, snap *runtime.Snapshot) (*Dashboard, error) {
	d := &Dashboard{}

	seen := map[int64]bool{}
	for _, rt := range snap.HostsByDomain {
		if seen[rt.Model.ID] {
			continue
		}
		seen[rt.Model.ID] = true
		if rt.Model.Type == models.ProxyHostTypeProxy {
			d.ActiveProxyHosts++
		}
		if rt.Pool != nil {
			for _, b := range rt.Pool.Backends {
				d.BackendHealth = append(d.BackendHealth, BackendHealthEntry{
					ProxyHost: rt.Model.Name,
					Backend:   b.Model.Host,
					Healthy:   b.Healthy(),
				})
			}
		}
	}

	streams, err := database.ListStreams(db)
	if err != nil {
		return nil, err
	}
	for _, s := range streams {
		if !s.Enabled {
			continue
		}
		if s.Protocol == models.StreamTCP {
			d.ActiveTCPStreams++
		} else {
			d.ActiveUDPStreams++
		}
	}

	requestsLastHour, err := database.CountRequestLogsSince(db, "-1 hours")
	if err != nil {
		return nil, err
	}
	d.RequestsLastHour = requestsLastHour
	d.RequestsPerSecond = float64(requestsLastHour) / 3600.0

	totalToday, err := database.CountRequestLogsSince(db, "-24 hours")
	if err != nil {
		return nil, err
	}
	d.TotalRequestsToday = totalToday

	statuses, err := database.StatusBreakdownSince(db, "-24 hours")
	if err != nil {
		return nil, err
	}
	d.StatusBreakdown = statuses

	topHosts, err := database.TopHostsSince(db, "-24 hours", 10)
	if err != nil {
		return nil, err
	}
	d.TopHosts = topHosts

	topClients, err := database.TopClientsSince(db, "-24 hours", 10)
	if err != nil {
		return nil, err
	}
	d.TopClients = topClients

	recentErrors, err := database.RecentErrorsSince(db, "-24 hours", 20)
	if err != nil {
		return nil, err
	}
	d.RecentErrors = recentErrors

	certs, err := database.ListCertificates(db)
	if err != nil {
		return nil, err
	}
	for _, c := range certs {
		if c.NotAfter == nil {
			continue
		}
		days := int(c.NotAfter.Sub(time.Now()).Hours() / 24)
		if days <= 30 {
			d.CertsExpiringSoon = append(d.CertsExpiringSoon, c)
		}
	}

	return d, nil
}