package checker

import (
	"context"
	"fmt"
	"strings"

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

func Rule() sdk.CheckRule {
	return &sipRule{}
}

type sipRule struct{}

func (r *sipRule) Name() string {
	return "sip_server"
}

func (r *sipRule) Description() string {
	return "Checks DNS resolution, reachability and OPTIONS response of a SIP/VoIP server"
}

func (r *sipRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, opts sdk.CheckerOptions) sdk.CheckState {
	var data SIPData
	if err := obs.Get(ctx, ObservationKeySIP, &data); err != nil {
		return sdk.CheckState{
			Status:  sdk.StatusError,
			Message: fmt.Sprintf("failed to load SIP observation: %v", err),
			Code:    "sip.observation_error",
		}
	}

	issues := append([]Issue(nil), data.Issues...)

	// Fold in related TLS observations so cert issues surface on the
	// SIP page without requiring a separate glance at the TLS report.
	related, _ := obs.GetRelated(ctx, TLSRelatedKey)
	issues = append(issues, tlsIssuesFromRelated(related)...)

	worst := sdk.StatusOK
	critMsgs, warnMsgs := []string{}, []string{}
	var firstCritCode, firstWarnCode string

	for _, is := range issues {
		switch is.Severity {
		case SeverityCrit:
			if worst < sdk.StatusCrit {
				worst = sdk.StatusCrit
			}
			if firstCritCode == "" {
				firstCritCode = is.Code
			}
			critMsgs = append(critMsgs, is.Message)
		case SeverityWarn:
			if worst < sdk.StatusWarn {
				worst = sdk.StatusWarn
			}
			if firstWarnCode == "" {
				firstWarnCode = is.Code
			}
			warnMsgs = append(warnMsgs, is.Message)
		}
	}

	transports := []string{}
	if data.Coverage.WorkingUDP {
		transports = append(transports, "udp")
	}
	if data.Coverage.WorkingTCP {
		transports = append(transports, "tcp")
	}
	if data.Coverage.WorkingTLS {
		transports = append(transports, "tls")
	}

	meta := map[string]any{
		"working_udp": data.Coverage.WorkingUDP,
		"working_tcp": data.Coverage.WorkingTCP,
		"working_tls": data.Coverage.WorkingTLS,
		"has_ipv4":    data.Coverage.HasIPv4,
		"has_ipv6":    data.Coverage.HasIPv6,
		"endpoints":   len(data.Endpoints),
		"issue_count": len(data.Issues),
	}

	switch worst {
	case sdk.StatusOK:
		return sdk.CheckState{
			Status:  sdk.StatusOK,
			Message: fmt.Sprintf("SIP operational (%s, %d endpoints)", strings.Join(transports, "+"), len(data.Endpoints)),
			Code:    "sip.ok",
			Meta:    meta,
		}
	case sdk.StatusWarn:
		return sdk.CheckState{
			Status:  sdk.StatusWarn,
			Message: "SIP works with warnings: " + joinTop(warnMsgs, 2),
			Code:    firstWarnCode,
			Meta:    meta,
		}
	default:
		return sdk.CheckState{
			Status:  sdk.StatusCrit,
			Message: "SIP broken: " + joinTop(critMsgs, 2),
			Code:    firstCritCode,
			Meta:    meta,
		}
	}
}

func joinTop(msgs []string, n int) string {
	if len(msgs) == 0 {
		return ""
	}
	if len(msgs) <= n {
		return strings.Join(msgs, "; ")
	}
	return strings.Join(msgs[:n], "; ") + fmt.Sprintf(" (+%d more)", len(msgs)-n)
}