package checker

import (
	"context"
	"fmt"
	"slices"
	"strings"

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

// validateXMPPOptions is the shared options validator for both the provider
// and the aggregate rule.
func validateXMPPOptions(opts sdk.CheckerOptions) error {
	if v, ok := opts["mode"]; ok {
		if s, ok := v.(string); ok && s != "" && !slices.Contains(validModes, s) {
			return fmt.Errorf(`mode must be "c2s", "s2s", or "both"`)
		}
	}
	return nil
}

// ValidateOptions implements sdk.OptionsValidator on the provider.
func (p *xmppProvider) ValidateOptions(opts sdk.CheckerOptions) error {
	return validateXMPPOptions(opts)
}

// xmppRule is a minimal back-compat aggregate rule. Newer deployments should
// prefer the split per-concern rules exposed by Rules(); this one is kept so
// existing tests that compose a single-status output keep working.
type xmppRule struct{}

func (r *xmppRule) Name() string { return "xmpp_server" }
func (r *xmppRule) Description() string {
	return "Aggregate XMPP posture (prefer the per-concern rules)."
}

func (r *xmppRule) ValidateOptions(opts sdk.CheckerOptions) error {
	return validateXMPPOptions(opts)
}

func (r *xmppRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, opts sdk.CheckerOptions) []sdk.CheckState {
	data, errSt := loadXMPPData(ctx, obs)
	if errSt != nil {
		return []sdk.CheckState{*errSt}
	}
	wantC2S, wantS2S := wantsFromOpts(opts)
	issues := deriveIssues(data, wantC2S, wantS2S)

	// Fold related TLS observations into the aggregate so cert/chain
	// problems surface on the XMPP service page.
	related, _ := obs.GetRelated(ctx, TLSRelatedKey)
	issues = append(issues, tlsIssuesFromRelated(related)...)

	worst := sdk.StatusOK
	var critMsgs, warnMsgs []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)
		}
	}

	if (wantC2S && !data.Coverage.WorkingC2S) || (wantS2S && !data.Coverage.WorkingS2S) {
		if worst < sdk.StatusCrit {
			worst = sdk.StatusCrit
		}
		var missing []string
		if wantC2S && !data.Coverage.WorkingC2S {
			missing = append(missing, "c2s")
		}
		if wantS2S && !data.Coverage.WorkingS2S {
			missing = append(missing, "s2s")
		}
		critMsgs = append(critMsgs, "no working "+joinModes(missing)+" endpoint")
		if firstCritCode == "" {
			firstCritCode = CodeAllEndpointsDown
		}
	}

	meta := map[string]any{
		"working_c2s": data.Coverage.WorkingC2S,
		"working_s2s": data.Coverage.WorkingS2S,
		"has_ipv4":    data.Coverage.HasIPv4,
		"has_ipv6":    data.Coverage.HasIPv6,
		"endpoints":   len(data.Endpoints),
		"issue_count": len(issues),
	}

	switch worst {
	case sdk.StatusOK:
		return []sdk.CheckState{{
			Status:  sdk.StatusOK,
			Message: fmt.Sprintf("XMPP operational (c2s=%v, s2s=%v, %d endpoints)", data.Coverage.WorkingC2S, data.Coverage.WorkingS2S, len(data.Endpoints)),
			Code:    "xmpp.ok",
			Meta:    meta,
		}}
	case sdk.StatusWarn:
		return []sdk.CheckState{{
			Status:  sdk.StatusWarn,
			Message: "XMPP works with warnings: " + joinTop(warnMsgs, 2),
			Code:    firstWarnCode,
			Meta:    meta,
		}}
	default:
		return []sdk.CheckState{{
			Status:  sdk.StatusCrit,
			Message: "XMPP broken: " + joinTop(critMsgs, 2),
			Code:    firstCritCode,
			Meta:    meta,
		}}
	}
}

func joinModes(ms []string) string {
	switch len(ms) {
	case 0:
		return ""
	case 1:
		return ms[0]
	default:
		return ms[0] + "/" + ms[1]
	}
}

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)
}