package cluster

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"
	"unicode"

	"scm.bstein.dev/bstein/ananke/internal/config"
)

// isLikelyHostname runs one orchestration or CLI step.
// Signature: isLikelyHostname(value string) bool.
// Why: keeps behavior explicit so startup/shutdown workflows remain maintainable as services evolve.
func isLikelyHostname(value string) bool {
	value = strings.TrimSpace(value)
	if value == "" {
		return false
	}
	if strings.Contains(value, " ") || strings.Contains(value, "/") {
		return false
	}
	return strings.Contains(value, ".")
}

// healIngressHostBackendReplicas runs one orchestration or CLI step.
// Signature: (o *Orchestrator) healIngressHostBackendReplicas(ctx context.Context, host string) ([]string, error).
// Why: keeps behavior explicit so startup/shutdown workflows remain maintainable as services evolve.
func (o *Orchestrator) healIngressHostBackendReplicas(ctx context.Context, host string) ([]string, error) {
	namespaces, err := o.discoverIngressNamespacesForHost(ctx, host)
	if err != nil {
		return nil, err
	}
	if len(namespaces) == 0 {
		return nil, nil
	}
	targetNamespaces := makeStringSet(namespaces)
	out, err := o.kubectl(ctx, 30*time.Second, "get", "deploy,statefulset", "-A", "-o", "json")
	if err != nil {
		return nil, fmt.Errorf("query workloads: %w", err)
	}
	var list workloadList
	if err := json.Unmarshal([]byte(out), &list); err != nil {
		return nil, fmt.Errorf("decode workloads: %w", err)
	}
	healed := []string{}
	for _, item := range list.Items {
		kind := strings.ToLower(strings.TrimSpace(item.Kind))
		ns := strings.TrimSpace(item.Metadata.Namespace)
		name := strings.TrimSpace(item.Metadata.Name)
		if kind == "" || ns == "" || name == "" {
			continue
		}
		if kind != "deployment" && kind != "statefulset" {
			continue
		}
		if _, ok := targetNamespaces[ns]; !ok {
			continue
		}
		desired := int32(1)
		if item.Spec.Replicas != nil {
			desired = *item.Spec.Replicas
		}
		if desired >= 1 {
			continue
		}
		workload := startupWorkload{Namespace: ns, Kind: kind, Name: name}
		if err := o.ensureWorkloadReplicas(ctx, workload, 1); err != nil {
			if isNotFoundErr(err) {
				continue
			}
			return healed, fmt.Errorf("scale %s/%s/%s to 1: %w", ns, kind, name, err)
		}
		healed = append(healed, ns+"/"+kind+"/"+name)
	}
	return healed, nil
}

// waitForServiceChecklist runs one orchestration or CLI step.
// Signature: (o *Orchestrator) waitForServiceChecklist(ctx context.Context) error.
// Why: keeps behavior explicit so startup/shutdown workflows remain maintainable as services evolve.
func (o *Orchestrator) waitForServiceChecklist(ctx context.Context) error {
	wait := time.Duration(o.cfg.Startup.ServiceChecklistWaitSeconds) * time.Second
	if wait <= 0 {
		wait = 7 * time.Minute
	}
	poll := time.Duration(o.cfg.Startup.ServiceChecklistPollSeconds) * time.Second
	if poll <= 0 {
		poll = 5 * time.Second
	}
	deadline := time.Now().Add(wait)
	lastFailure := "unknown"
	lastLogged := time.Time{}
	lastRecycleAttempt := time.Time{}
	lastReplicaHeal := time.Time{}
	lastIngressHeal := time.Time{}
	for {
		o.maybeAutoRecycleStuckPods(ctx, &lastRecycleAttempt)
		o.maybeAutoHealCriticalWorkloadReplicas(ctx, &lastReplicaHeal)
		prevFailure := lastFailure
		ready, detail := o.serviceChecklistReady(ctx)
		lastFailure = detail
		if ready {
			o.log.Printf("external service checklist passed (%s)", detail)
			return nil
		}
		o.maybeAutoHealIngressHostBackends(ctx, &lastIngressHeal, lastFailure)
		if lastFailure != prevFailure || time.Since(lastLogged) >= 30*time.Second {
			remaining := time.Until(deadline).Round(time.Second)
			if remaining < 0 {
				remaining = 0
			}
			o.log.Printf("waiting for external service checklist (%s remaining): %s", remaining, lastFailure)
			lastLogged = time.Now()
		}
		if time.Now().After(deadline) {
			return fmt.Errorf("startup blocked: external service checklist not satisfied within %s (%s)", wait, lastFailure)
		}
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-time.After(poll):
		}
	}
}

// serviceChecklistReady runs one orchestration or CLI step.
// Signature: (o *Orchestrator) serviceChecklistReady(ctx context.Context) (bool, string).
// Why: keeps behavior explicit so startup/shutdown workflows remain maintainable as services evolve.
func (o *Orchestrator) serviceChecklistReady(ctx context.Context) (bool, string) {
	checks := o.cfg.Startup.ServiceChecklist
	if len(checks) == 0 {
		return true, "no checklist items configured"
	}
	for _, check := range checks {
		ok, detail := o.serviceCheckReady(ctx, check)
		if !ok {
			name := strings.TrimSpace(check.Name)
			if name == "" {
				name = strings.TrimSpace(check.URL)
			}
			return false, fmt.Sprintf("%s: %s", name, detail)
		}
	}
	return true, fmt.Sprintf("checks=%d", len(checks))
}

// serviceCheckReady runs one orchestration or CLI step.
// Signature: (o *Orchestrator) serviceCheckReady(ctx context.Context, check config.ServiceChecklistCheck) (bool, string).
// Why: keeps behavior explicit so startup/shutdown workflows remain maintainable as services evolve.
func (o *Orchestrator) serviceCheckReady(ctx context.Context, check config.ServiceChecklistCheck) (bool, string) {
	result, err := o.httpChecklistProbeResult(ctx, check)
	if err != nil {
		return false, err.Error()
	}

	accepted := check.AcceptedStatuses
	if len(accepted) == 0 {
		accepted = []int{200, 201, 202, 203, 204, 301, 302, 303, 307, 308, 401, 403}
	}
	statusOk := false
	for _, code := range accepted {
		if result.Status == code {
			statusOk = true
			break
		}
	}
	if !statusOk {
		return false, fmt.Sprintf("unexpected status code=%d", result.Status)
	}

	locationContains := strings.TrimSpace(check.LocationContains)
	if locationContains != "" && !checklistContains(result.Location, locationContains) {
		return false, fmt.Sprintf("location header missing expected marker %q", locationContains)
	}

	locationNotContains := strings.TrimSpace(check.LocationNotContains)
	if locationNotContains != "" && checklistContains(result.Location, locationNotContains) {
		return false, fmt.Sprintf("location header contained forbidden marker %q", locationNotContains)
	}

	finalURLContains := strings.TrimSpace(check.FinalURLContains)
	if finalURLContains != "" && !checklistContains(result.FinalURL, finalURLContains) {
		return false, fmt.Sprintf("final url missing expected marker %q", finalURLContains)
	}

	finalURLNotContains := strings.TrimSpace(check.FinalURLNotContains)
	if finalURLNotContains != "" && checklistContains(result.FinalURL, finalURLNotContains) {
		return false, fmt.Sprintf("final url contained forbidden marker %q", finalURLNotContains)
	}

	bodyContains := strings.TrimSpace(check.BodyContains)
	if bodyContains != "" && !checklistContains(result.Body, bodyContains) {
		return false, fmt.Sprintf("response missing expected marker %q", bodyContains)
	}

	bodyNotContains := strings.TrimSpace(check.BodyNotContains)
	if bodyNotContains != "" && checklistContains(result.Body, bodyNotContains) {
		return false, fmt.Sprintf("response contained forbidden marker %q", bodyNotContains)
	}

	return true, fmt.Sprintf("status=%d", result.Status)
}

type checklistHTTPProbeResult struct {
	Status   int
	Body     string
	Location string
	FinalURL string
}

// httpChecklistProbeResult runs one orchestration or CLI step.
// Signature: (o *Orchestrator) httpChecklistProbeResult(ctx context.Context, check config.ServiceChecklistCheck) (checklistHTTPProbeResult, error).
// Why: checklist checks need response headers (for redirect verification) in
// addition to status/body so startup can validate real user-facing behavior.
func (o *Orchestrator) httpChecklistProbeResult(ctx context.Context, check config.ServiceChecklistCheck) (checklistHTTPProbeResult, error) {
	result := checklistHTTPProbeResult{}
	status, body, location, finalURL, err := o.httpChecklistProbeWithLocation(ctx, check)
	if err != nil {
		return result, err
	}
	result.Status = status
	result.Body = body
	result.Location = location
	result.FinalURL = finalURL
	return result, nil
}

// httpChecklistProbe runs one orchestration or CLI step.
// Signature: (o *Orchestrator) httpChecklistProbe(ctx context.Context, check config.ServiceChecklistCheck) (int, string, error).
// Why: keeps behavior explicit so startup/shutdown workflows remain maintainable as services evolve.
func (o *Orchestrator) httpChecklistProbe(ctx context.Context, check config.ServiceChecklistCheck) (int, string, error) {
	status, body, _, _, err := o.httpChecklistProbeWithLocation(ctx, check)
	return status, body, err
}

// httpChecklistProbeWithLocation runs one orchestration or CLI step.
// Signature: (o *Orchestrator) httpChecklistProbeWithLocation(ctx context.Context, check config.ServiceChecklistCheck) (int, string, string, string, error).
// Why: redirects and auth gates require location-header assertions to prevent
// startup false-positives on partially healthy protected services.
func (o *Orchestrator) httpChecklistProbeWithLocation(ctx context.Context, check config.ServiceChecklistCheck) (int, string, string, string, error) {
	timeout := time.Duration(check.TimeoutSeconds) * time.Second
	if timeout <= 0 {
		timeout = 12 * time.Second
	}

	followRedirects := check.FollowRedirects || check.RequireRobotAuth
	var client *http.Client
	if check.RequireRobotAuth {
		authClient, authErr := o.checklistAuthHTTPClient(ctx, timeout, check.InsecureSkipTLS)
		if authErr != nil {
			return 0, "", "", "", fmt.Errorf("initialize robotuser checklist session: %w", authErr)
		}
		client = authClient
	} else {
		transport := &http.Transport{}
		if check.InsecureSkipTLS {
			transport.TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
		}
		client = &http.Client{
			Timeout:   timeout,
			Transport: transport,
		}
	}
	if !followRedirects {
		client.CheckRedirect = func(_ *http.Request, _ []*http.Request) error {
			return http.ErrUseLastResponse
		}
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, strings.TrimSpace(check.URL), nil)
	if err != nil {
		return 0, "", "", "", fmt.Errorf("build request: %w", err)
	}
	req.Header.Set("User-Agent", "ananke/startup-checklist")

	resp, err := client.Do(req)
	if err != nil {
		return 0, "", "", "", fmt.Errorf("request failed: %w", err)
	}
	defer resp.Body.Close()

	body, readErr := io.ReadAll(io.LimitReader(resp.Body, 64*1024))
	if readErr != nil {
		return resp.StatusCode, "", "", "", fmt.Errorf("read response body: %w", readErr)
	}

	finalURL := strings.TrimSpace(req.URL.String())
	if resp.Request != nil && resp.Request.URL != nil {
		finalURL = strings.TrimSpace(resp.Request.URL.String())
	}
	return resp.StatusCode, string(body), strings.TrimSpace(resp.Header.Get("Location")), finalURL, nil
}

// checklistContains runs one orchestration or CLI step.
// Signature: checklistContains(body, marker string) bool.
// Why: keeps behavior explicit so startup/shutdown workflows remain maintainable as services evolve.
func checklistContains(body, marker string) bool {
	bodyLower := strings.ToLower(body)
	markerLower := strings.ToLower(marker)
	if strings.Contains(bodyLower, markerLower) {
		return true
	}
	bodyCompact := compactLowerNoSpace(bodyLower)
	markerCompact := compactLowerNoSpace(markerLower)
	if markerCompact == "" {
		return true
	}
	return strings.Contains(bodyCompact, markerCompact)
}

// compactLowerNoSpace runs one orchestration or CLI step.
// Signature: compactLowerNoSpace(s string) string.
// Why: keeps behavior explicit so startup/shutdown workflows remain maintainable as services evolve.
func compactLowerNoSpace(s string) string {
	var b strings.Builder
	b.Grow(len(s))
	for _, r := range s {
		if unicode.IsSpace(r) {
			continue
		}
		b.WriteRune(r)
	}
	return b.String()
}

// waitForStabilityWindow runs one orchestration or CLI step.
// Signature: (o *Orchestrator) waitForStabilityWindow(ctx context.Context) error.
// Why: keeps behavior explicit so startup/shutdown workflows remain maintainable as services evolve.
func (o *Orchestrator) waitForStabilityWindow(ctx context.Context) error {
	window := time.Duration(o.cfg.Startup.ServiceChecklistStabilitySec) * time.Second
	if window <= 0 {
		return nil
	}
	poll := time.Duration(o.cfg.Startup.ServiceChecklistPollSeconds) * time.Second
	if poll <= 0 {
		poll = 5 * time.Second
	}
	deadline := time.Now().Add(window)
	lastStatus := time.Time{}
	lastRecycleAttempt := time.Time{}
	lastReplicaHeal := time.Time{}

	for {
		o.maybeAutoRecycleStuckPods(ctx, &lastRecycleAttempt)
		o.maybeAutoHealCriticalWorkloadReplicas(ctx, &lastReplicaHeal)
		if err := o.startupStabilityHealthy(ctx); err != nil {
			return fmt.Errorf("startup stability window failed: %w", err)
		}
		if time.Now().After(deadline) {
			o.log.Printf("startup stability window passed (%s)", window)
			return nil
		}
		if time.Since(lastStatus) >= 30*time.Second {
			remaining := time.Until(deadline).Round(time.Second)
			if remaining < 0 {
				remaining = 0
			}
			o.log.Printf("startup stability soak in progress (%s remaining)", remaining)
			lastStatus = time.Now()
		}
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-time.After(poll):
		}
	}
}

// startupStabilityHealthy runs one orchestration or CLI step.
// Signature: (o *Orchestrator) startupStabilityHealthy(ctx context.Context) error.
// Why: keeps behavior explicit so startup/shutdown workflows remain maintainable as services evolve.
func (o *Orchestrator) startupStabilityHealthy(ctx context.Context) error {
	if o.cfg.Startup.RequireFluxHealth {
		ready, detail, err := o.fluxHealthReady(ctx)
		if err != nil {
			return fmt.Errorf("flux check error: %w", err)
		}
		if !ready {
			return fmt.Errorf("flux not ready: %s", detail)
		}
	}
	if o.cfg.Startup.RequireWorkloadConvergence {
		ready, detail, err := o.workloadConvergenceReady(ctx)
		if err != nil {
			return fmt.Errorf("workload check error: %w", err)
		}
		if !ready {
			return fmt.Errorf("workloads not converged: %s", detail)
		}
	}
	if o.cfg.Startup.RequireServiceChecklist {
		ready, detail := o.serviceChecklistReady(ctx)
		if !ready {
			return fmt.Errorf("external services not healthy: %s", detail)
		}
	}
	if o.cfg.Startup.RequireIngressChecklist {
		ready, detail := o.ingressChecklistReady(ctx)
		if !ready {
			return fmt.Errorf("ingress reachability not healthy: %s", detail)
		}
	}
	failures, err := o.startupFailurePods(ctx)
	if err != nil {
		return fmt.Errorf("pod failure check error: %w", err)
	}
	if len(failures) > 0 {
		return fmt.Errorf("pods in crash/image-pull failures: %s", joinLimited(failures, 8))
	}
	return nil
}