package checker

import (
	"context"

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

// c2sReachableRule verifies that at least one client-to-server endpoint
// is reachable (TCP + TLS) and that no discovered c2s endpoint is down.
type c2sReachableRule struct{}

func (r *c2sReachableRule) Name() string { return "xmpp.c2s_reachable" }
func (r *c2sReachableRule) Description() string {
	return "Verifies that at least one client-to-server endpoint accepts TCP and completes TLS."
}

func (r *c2sReachableRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, opts sdk.CheckerOptions) []sdk.CheckState {
	return evaluateReachable(ctx, obs, opts, ModeClient)
}

// s2sReachableRule is the s2s counterpart.
type s2sReachableRule struct{}

func (r *s2sReachableRule) Name() string { return "xmpp.s2s_reachable" }
func (r *s2sReachableRule) Description() string {
	return "Verifies that at least one server-to-server endpoint accepts TCP and completes TLS."
}

func (r *s2sReachableRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, opts sdk.CheckerOptions) []sdk.CheckState {
	return evaluateReachable(ctx, obs, opts, ModeServer)
}

func evaluateReachable(ctx context.Context, obs sdk.ObservationGetter, opts sdk.CheckerOptions, mode XMPPMode) []sdk.CheckState {
	data, errSt := loadXMPPData(ctx, obs)
	if errSt != nil {
		return []sdk.CheckState{*errSt}
	}
	wantC2S, wantS2S := wantsFromOpts(opts)
	if mode == ModeClient && !wantC2S {
		return []sdk.CheckState{notTestedState("xmpp.c2s_reachable.skipped", "c2s not in scope for the selected mode.")}
	}
	if mode == ModeServer && !wantS2S {
		return []sdk.CheckState{notTestedState("xmpp.s2s_reachable.skipped", "s2s not in scope for the selected mode.")}
	}

	// Per-endpoint TCP unreachable states for this mode.
	var states []sdk.CheckState
	anyForMode := false
	for _, ep := range data.Endpoints {
		if ep.Mode != mode {
			continue
		}
		anyForMode = true
		if !ep.TCPConnected && ep.Error != "" {
			states = append(states, sdk.CheckState{
				Status:  sdk.StatusWarn,
				Message: "Cannot reach " + ep.Address + ": " + ep.Error + ".",
				Code:    CodeTCPUnreachable,
				Subject: ep.Address,
				Meta:    map[string]any{"fix": "Verify firewall rules and that the XMPP server is listening on this address."},
			})
		}
	}

	if !anyForMode {
		return []sdk.CheckState{{
			Status:  sdk.StatusCrit,
			Message: "No " + string(mode) + " endpoint discovered to probe.",
			Code:    CodeNoSRV,
		}}
	}

	working := data.Coverage.WorkingC2S
	if mode == ModeServer {
		working = data.Coverage.WorkingS2S
	}
	if !working {
		states = append(states, sdk.CheckState{
			Status:  sdk.StatusCrit,
			Message: "No working " + string(mode) + " endpoint (TCP + TLS).",
			Code:    CodeAllEndpointsDown,
		})
	}

	if len(states) == 0 {
		code := "xmpp.c2s_reachable.ok"
		if mode == ModeServer {
			code = "xmpp.s2s_reachable.ok"
		}
		return []sdk.CheckState{passState(code, "At least one "+string(mode)+" endpoint is reachable and completes TLS.")}
	}
	return states
}