package checker

import (
	"context"
	"net"
	"strings"

	sdk "git.happydns.org/checker-sdk-go/checker"
)

// turnTLSTransportRule evaluates whether a TLS-capable transport is
// available and reports its version/cipher metadata. Kept separate from
// the generic dial rule because TURN-TLS deployments often need dedicated
// attention (port 5349, certificate covering the TURN hostname, …).
type turnTLSTransportRule struct{}

func (r *turnTLSTransportRule) Name() string { return "stun_turn.tls_transport" }
func (r *turnTLSTransportRule) Description() string {
	return "Verifies that at least one TLS/DTLS transport (stuns/turns) succeeds when present in the endpoint set."
}

func (r *turnTLSTransportRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, _ sdk.CheckerOptions) []sdk.CheckState {
	data, errSt := loadData(ctx, obs)
	if errSt != nil {
		return []sdk.CheckState{*errSt}
	}
	var (
		secureCount, secureOK int
		states                []sdk.CheckState
	)
	for _, ep := range data.Endpoints {
		if !ep.Endpoint.Secure {
			continue
		}
		secureCount++
		if ep.Dial.OK {
			secureOK++
			continue
		}
		states = append(states, sdk.CheckState{
			Status:  sdk.StatusCrit,
			Code:    "stun_turn.tls_transport.handshake_failed",
			Subject: epSubject(ep.Endpoint),
			Message: ep.Dial.Error,
			Meta: map[string]any{
				"fix": "TLS/DTLS handshake failed. Reissue a certificate covering the TURN hostname and reload the server (coturn: `cert=`/`pkey=`).",
			},
		})
	}
	if secureCount == 0 {
		return []sdk.CheckState{skippedState("stun_turn.tls_transport.skipped", "No secure (stuns/turns) endpoint discovered.")}
	}
	if secureOK == 0 {
		// All secure endpoints failed, already emitted per-endpoint
		// crit states; return them as-is.
		return states
	}
	if len(states) == 0 {
		return []sdk.CheckState{passState("stun_turn.tls_transport.ok", "TLS/DTLS handshake succeeded on every secure endpoint.")}
	}
	return states
}

// ipv6CoverageRule verifies at least one endpoint resolves to an IPv6
// address. It never marks an endpoint failed: missing AAAA records are a
// coverage concern, not an error.
type ipv6CoverageRule struct{}

func (r *ipv6CoverageRule) Name() string { return "stun_turn.ipv6_coverage" }
func (r *ipv6CoverageRule) Description() string {
	return "Verifies at least one STUN/TURN hostname resolves to an IPv6 address."
}

func (r *ipv6CoverageRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, _ sdk.CheckerOptions) []sdk.CheckState {
	data, errSt := loadData(ctx, obs)
	if errSt != nil {
		return []sdk.CheckState{*errSt}
	}
	if len(data.Endpoints) == 0 {
		return []sdk.CheckState{skippedState("stun_turn.ipv6_coverage.skipped", "No endpoint discovered.")}
	}
	var anyResolved, anyV6 bool
	for _, ep := range data.Endpoints {
		for _, ipStr := range ep.ResolvedIPs {
			anyResolved = true
			ip := net.ParseIP(ipStr)
			if ip != nil && ip.To4() == nil && strings.Contains(ipStr, ":") {
				anyV6 = true
				break
			}
		}
		if anyV6 {
			break
		}
	}
	if !anyResolved {
		return []sdk.CheckState{skippedState("stun_turn.ipv6_coverage.skipped", "Hostname resolution data unavailable.")}
	}
	if !anyV6 {
		return []sdk.CheckState{{
			Status:  sdk.StatusWarn,
			Code:    "stun_turn.ipv6_coverage.missing",
			Message: "No STUN/TURN endpoint resolves to an IPv6 address; IPv6-only clients will have no reachable server.",
			Meta:    map[string]any{"fix": "Publish AAAA records for your STUN/TURN hostnames and ensure the server listens on IPv6."},
		}}
	}
	return []sdk.CheckState{passState("stun_turn.ipv6_coverage.ok", "At least one endpoint resolves to an IPv6 address.")}
}