package controlplane

import (
	"context"
	"encoding/json"
	"io"
	"log/slog"
	"net/http"
	"strings"
	"time"

	"git.toki-labs.com/toki/gito/services/core/internal/config"
	"git.toki-labs.com/toki/gito/services/core/internal/protosocket"
	"git.toki-labs.com/toki/gito/services/core/internal/provider"
	"git.toki-labs.com/toki/gito/services/core/internal/provider/forgejo"
	"git.toki-labs.com/toki/gito/services/core/internal/storage"
)

func NewRouter(cfg config.Config, logger *slog.Logger) http.Handler {
	return newRouterWithStore(cfg, logger, nil)
}

// NewRouterWithStore constructs a router backed by the given durable store.
// Pass nil to fall back to in-memory runtime (same as NewRouter).
func NewRouterWithStore(cfg config.Config, logger *slog.Logger, store storage.Store) http.Handler {
	return newRouterWithStore(cfg, logger, store)
}

func newRouterWithStore(cfg config.Config, logger *slog.Logger, store storage.Store) http.Handler {
	mux := http.NewServeMux()
	protoServer := protosocket.NewServer(protosocket.Config{
		HeartbeatIntervalSec: cfg.ProtoSocketHeartbeatSec,
		HeartbeatWaitSec:     cfg.ProtoSocketHeartbeatWait,
	}, logger)
	runtime := NewRuntimeWithStore(protoServer, store)
	registerProtoSocketHandlers(protoServer.Dispatcher(), runtime, protoServer)

	mux.HandleFunc("/healthz", func(w http.ResponseWriter, _ *http.Request) {
		writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
	})
	mux.HandleFunc("/readyz", func(w http.ResponseWriter, _ *http.Request) {
		writeJSON(w, http.StatusOK, map[string]string{
			"status": "ready",
			"env":    cfg.AppEnv,
		})
	})
	mux.HandleFunc("/api/listeners/branches", handleBranchListeners(runtime))
	mux.HandleFunc("/api/webhook-subscriptions", handleWebhookSubscriptions(runtime))
	mux.HandleFunc("/api/events", handleEvents(runtime))
	mux.HandleFunc("/callbacks/providers/", handleProviderWebhook(runtime))
	mux.HandleFunc("/callbacks/forgejo/push", handleForgejoPush(cfg, runtime))
	mux.HandleFunc(cfg.ProtoSocketPath, func(w http.ResponseWriter, r *http.Request) {
		if isWebSocketUpgrade(r) {
			protoServer.ServeHTTP(w, r)
			return
		}
		if r.Method != http.MethodGet {
			w.Header().Set("Allow", http.MethodGet)
			writeJSON(w, http.StatusMethodNotAllowed, map[string]string{
				"error": "method not allowed",
			})
			return
		}
		logger.Info("proto-socket registry scaffold", "path", r.URL.Path)
		writeJSON(w, http.StatusOK, DefaultProtoSocketRegistry())
	})
	return mux
}

func registerProtoSocketHandlers(dispatcher *protosocket.Dispatcher, runtime *Runtime, subscriber protosocket.EventSubscriber) {
	dispatcher.Register("event.subscribe", func(_ context.Context, env protosocket.Envelope) protosocket.Envelope {
		connectionID := stringValue(env.Meta["connection_id"])
		if connectionID == "" {
			return protosocket.ErrorResponse(env, "event.missing_connection", "event.subscribe requires a proto-socket connection id", false)
		}
		subscription := eventSubscriptionFromPayload(env.Payload)
		registered := subscriber.Subscribe(connectionID, subscription)
		return protosocket.SuccessResponse(env, map[string]any{
			"status":       "subscribed",
			"subscription": registered.Payload(),
		})
	})
	dispatcher.Register("event.list", func(_ context.Context, env protosocket.Envelope) protosocket.Envelope {
		return protosocket.SuccessResponse(env, map[string]any{
			"events": eventRecordsPayload(runtime.ListEvents()),
		})
	})
}

func eventSubscriptionFromPayload(payload map[string]any) protosocket.EventSubscription {
	events := stringListValue(payload["events"])
	if len(events) == 0 {
		events = []string{"branch.updated"}
	}
	return protosocket.EventSubscription{
		Events: events,
		RepoID: stringValue(payload["repo_id"]),
		Branch: stringValue(payload["branch"]),
	}
}

func stringListValue(value any) []string {
	items, ok := value.([]any)
	if !ok {
		if values, ok := value.([]string); ok {
			return values
		}
		return nil
	}
	result := make([]string, 0, len(items))
	for _, item := range items {
		if text := stringValue(item); text != "" {
			result = append(result, text)
		}
	}
	return result
}

func stringValue(value any) string {
	text, ok := value.(string)
	if !ok {
		return ""
	}
	return strings.TrimSpace(text)
}

func handleBranchListeners(runtime *Runtime) http.HandlerFunc {
	type request struct {
		RepoID   string `json:"repo_id"`
		Branch   string `json:"branch"`
		Provider string `json:"provider"`
	}
	return func(w http.ResponseWriter, r *http.Request) {
		switch r.Method {
		case http.MethodGet:
			writeJSON(w, http.StatusOK, map[string]any{"listeners": runtime.ListBranchWatches()})
		case http.MethodPost:
			var input request
			if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
				writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid listener payload"})
				return
			}
			watch, err := runtime.RegisterBranchWatch(input.RepoID, input.Branch, input.Provider)
			if err != nil {
				writeJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
				return
			}
			writeJSON(w, http.StatusCreated, map[string]any{"listener": watch})
		default:
			w.Header().Set("Allow", "GET, POST")
			writeJSON(w, http.StatusMethodNotAllowed, map[string]string{"error": "method not allowed"})
		}
	}
}

func handleWebhookSubscriptions(runtime *Runtime) http.HandlerFunc {
	type request struct {
		Name      string   `json:"name"`
		TargetURL string   `json:"target_url"`
		Events    []string `json:"events"`
		RepoID    string   `json:"repo_id"`
		Branch    string   `json:"branch"`
		SecretRef string   `json:"secret_ref"`
	}
	return func(w http.ResponseWriter, r *http.Request) {
		switch r.Method {
		case http.MethodGet:
			writeJSON(w, http.StatusOK, map[string]any{"subscriptions": webhookSubscriptionsPayload(runtime.ListWebhookSubscriptions())})
		case http.MethodPost:
			var input request
			if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
				writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid webhook subscription payload"})
				return
			}
			subscription, err := runtime.RegisterWebhookSubscription(
				input.Name,
				input.TargetURL,
				input.Events,
				input.RepoID,
				input.Branch,
				input.SecretRef,
			)
			if err != nil {
				writeJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
				return
			}
			writeJSON(w, http.StatusCreated, map[string]any{"subscription": webhookSubscriptionPayload(subscription)})
		default:
			w.Header().Set("Allow", "GET, POST")
			writeJSON(w, http.StatusMethodNotAllowed, map[string]string{"error": "method not allowed"})
		}
	}
}

func handleEvents(runtime *Runtime) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			w.Header().Set("Allow", http.MethodGet)
			writeJSON(w, http.StatusMethodNotAllowed, map[string]string{"error": "method not allowed"})
			return
		}
		writeJSON(w, http.StatusOK, map[string]any{"events": eventRecordsPayload(runtime.ListEvents())})
	}
}

func handleProviderWebhook(runtime *Runtime) http.HandlerFunc {
	const prefix = "/callbacks/providers/"
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			w.Header().Set("Allow", http.MethodPost)
			writeJSON(w, http.StatusMethodNotAllowed, map[string]string{"error": "method not allowed"})
			return
		}
		providerID := strings.Trim(strings.TrimPrefix(r.URL.Path, prefix), "/")
		if providerID == "" || strings.Contains(providerID, "/") {
			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "provider is required"})
			return
		}
		body, err := io.ReadAll(io.LimitReader(r.Body, 1<<20))
		if err != nil {
			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "failed to read payload"})
			return
		}
		record, err := runtime.HandleProviderWebhook(r.Context(), provider.WebhookRequest{
			Provider:   provider.ProviderID(providerID),
			EventType:  providerWebhookEventName(r),
			ExternalID: providerWebhookDeliveryID(r),
			Payload:    body,
			Headers:    map[string][]string(r.Header),
			Query:      r.URL.Query(),
			ReceivedAt: time.Now().UTC(),
		})
		if err != nil {
			writeJSON(w, http.StatusBadRequest, map[string]string{"error": err.Error()})
			return
		}
		writeJSON(w, http.StatusAccepted, map[string]any{
			"accepted": true,
			"event":    eventRecordPayload(record),
		})
	}
}

func handleForgejoPush(cfg config.Config, runtime *Runtime) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			w.Header().Set("Allow", http.MethodPost)
			writeJSON(w, http.StatusMethodNotAllowed, map[string]string{"error": "method not allowed"})
			return
		}
		body, err := io.ReadAll(io.LimitReader(r.Body, 1<<20))
		if err != nil {
			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "failed to read payload"})
			return
		}
		if strings.TrimSpace(cfg.ForgejoWebhookSecret) != "" &&
			!forgejo.VerifySignature(cfg.ForgejoWebhookSecret, body, r.Header.Get("X-Forgejo-Signature")) {
			writeJSON(w, http.StatusUnauthorized, map[string]string{"error": "invalid forgejo signature"})
			return
		}
		if eventName := webhookEventName(r); eventName != "" && eventName != "push" {
			writeJSON(w, http.StatusAccepted, map[string]any{"accepted": true, "matched": false, "reason": "unsupported event"})
			return
		}
		payload, err := forgejo.ParsePushPayload(body)
		if err != nil {
			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid forgejo push payload"})
			return
		}
		revision, err := forgejo.NormalizePush(payload, r.URL.Query().Get("repo_id"), time.Now().UTC())
		if err != nil {
			writeJSON(w, http.StatusAccepted, map[string]any{"accepted": true, "matched": false, "reason": "non-branch ref"})
			return
		}
		record, matched, err := runtime.HandleRevision(r.Context(), "forgejo", r.Header.Get("X-Forgejo-Delivery"), revision)
		if err != nil {
			writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "failed to publish event"})
			return
		}
		resp := map[string]any{
			"accepted": true,
			"matched":  matched,
		}
		if matched {
			resp["event"] = eventRecordPayload(record)
		}
		if record.Duplicate {
			resp["duplicate"] = true
		}
		writeJSON(w, http.StatusAccepted, resp)
	}
}

func webhookEventName(r *http.Request) string {
	for _, header := range []string{"X-Forgejo-Event", "X-Gitea-Event", "X-Gogs-Event", "X-GitHub-Event"} {
		if value := strings.TrimSpace(r.Header.Get(header)); value != "" {
			return strings.ToLower(value)
		}
	}
	return ""
}

func providerWebhookEventName(r *http.Request) string {
	for _, header := range []string{"X-Gito-Provider-Event", "X-GitHub-Event", "X-Forgejo-Event", "X-Gitea-Event", "X-Gogs-Event", "X-GitLab-Event"} {
		if value := strings.TrimSpace(r.Header.Get(header)); value != "" {
			return strings.ToLower(value)
		}
	}
	return ""
}

func providerWebhookDeliveryID(r *http.Request) string {
	for _, header := range []string{"X-Gito-Delivery", "X-GitHub-Delivery", "X-Forgejo-Delivery", "X-Gitea-Delivery", "X-Gogs-Delivery", "X-GitLab-Event-UUID"} {
		if value := strings.TrimSpace(r.Header.Get(header)); value != "" {
			return value
		}
	}
	return ""
}

func isWebSocketUpgrade(r *http.Request) bool {
	return strings.EqualFold(r.Header.Get("Upgrade"), "websocket") &&
		strings.Contains(strings.ToLower(r.Header.Get("Connection")), "upgrade")
}

type ProtoSocketRegistry struct {
	Transport string               `json:"transport"`
	Status    string               `json:"status"`
	Channels  []ProtoSocketChannel `json:"channels"`
}

type ProtoSocketChannel struct {
	Name    string              `json:"name"`
	Purpose string              `json:"purpose"`
	Status  string              `json:"status"`
	Actions []ProtoSocketAction `json:"actions"`
}

type ProtoSocketAction struct {
	Name   string `json:"name"`
	Status string `json:"status"`
}

func DefaultProtoSocketRegistry() ProtoSocketRegistry {
	return ProtoSocketRegistry{
		Transport: "proto-socket",
		Status:    "registry-placeholder",
		Channels: []ProtoSocketChannel{
			{
				Name:    "repo",
				Purpose: "register, inspect, and list managed repositories",
				Status:  "placeholder",
				Actions: []ProtoSocketAction{
					{Name: "register", Status: "placeholder"},
					{Name: "get", Status: "placeholder"},
					{Name: "list", Status: "placeholder"},
				},
			},
			{
				Name:    "workspace",
				Purpose: "lease, release, and inspect workspace slots",
				Status:  "placeholder",
				Actions: []ProtoSocketAction{
					{Name: "lease", Status: "placeholder"},
					{Name: "release", Status: "placeholder"},
					{Name: "get", Status: "placeholder"},
				},
			},
			{
				Name:    "operation",
				Purpose: "create, cancel, inspect, and stream operations",
				Status:  "placeholder",
				Actions: []ProtoSocketAction{
					{Name: "create", Status: "placeholder"},
					{Name: "cancel", Status: "placeholder"},
					{Name: "get", Status: "placeholder"},
					{Name: "stream", Status: "placeholder"},
				},
			},
			{
				Name:    "git",
				Purpose: "request platformless Git operations",
				Status:  "placeholder",
				Actions: []ProtoSocketAction{
					{Name: "clone", Status: "placeholder"},
					{Name: "fetch", Status: "placeholder"},
					{Name: "status", Status: "placeholder"},
					{Name: "diff", Status: "placeholder"},
					{Name: "commit", Status: "placeholder"},
					{Name: "push", Status: "placeholder"},
				},
			},
			{
				Name:    "change_request",
				Purpose: "manage provider-neutral change requests",
				Status:  "placeholder",
				Actions: []ProtoSocketAction{
					{Name: "open", Status: "placeholder"},
					{Name: "update", Status: "placeholder"},
					{Name: "list", Status: "placeholder"},
				},
			},
			{
				Name:    "agent_shell",
				Purpose: "shell heartbeat, command dispatch, and log streaming",
				Status:  "placeholder",
				Actions: []ProtoSocketAction{
					{Name: "heartbeat", Status: "placeholder"},
					{Name: "dispatch", Status: "placeholder"},
					{Name: "stream_logs", Status: "placeholder"},
				},
			},
			{
				Name:    "event",
				Purpose: "subscribe to normalized events",
				Status:  "mvp",
				Actions: []ProtoSocketAction{
					{Name: "subscribe", Status: "mvp"},
					{Name: "list", Status: "mvp"},
					{Name: "ack", Status: "placeholder"},
				},
			},
		},
	}
}

func writeJSON(w http.ResponseWriter, status int, value any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(value)
}

func eventRecordsPayload(records []EventRecord) []any {
	payload := make([]any, 0, len(records))
	for _, record := range records {
		payload = append(payload, eventRecordPayload(record))
	}
	return payload
}

func webhookSubscriptionsPayload(subscriptions []WebhookSubscription) []any {
	payload := make([]any, 0, len(subscriptions))
	for _, subscription := range subscriptions {
		payload = append(payload, webhookSubscriptionPayload(subscription))
	}
	return payload
}

func webhookSubscriptionPayload(subscription WebhookSubscription) map[string]any {
	return map[string]any{
		"id":         subscription.ID,
		"name":       subscription.Name,
		"events":     subscription.Events,
		"repo_id":    subscription.RepoID,
		"branch":     subscription.Branch,
		"created_at": subscription.CreatedAt.UTC().Format(time.RFC3339Nano),
	}
}

func eventRecordPayload(record EventRecord) map[string]any {
	payload := map[string]any{
		"id":          record.ID,
		"type":        record.Type,
		"provider":    record.Provider,
		"delivery_id": record.DeliveryID,
		"created_at":  record.CreatedAt.UTC().Format(time.RFC3339Nano),
	}
	if record.Type == "branch.updated" {
		changedFiles := make([]any, 0, len(record.Revision.ChangedFiles))
		for _, file := range record.Revision.ChangedFiles {
			changedFiles = append(changedFiles, map[string]any{
				"path":        file.Path,
				"change_type": file.ChangeType,
			})
		}
		payload["revision"] = map[string]any{
			"repo_id":       record.Revision.RepoID,
			"branch":        record.Revision.Branch,
			"before":        record.Revision.Before,
			"after":         record.Revision.After,
			"changed_files": changedFiles,
			"observed_at":   record.Revision.ObservedAt.UTC().Format(time.RFC3339Nano),
		}
	}
	if record.Type == "provider.webhook.received" && record.Webhook != nil {
		payload["webhook"] = map[string]any{
			"event_type":   record.Webhook.EventType,
			"external_id":  record.Webhook.ExternalID,
			"payload_size": record.Webhook.PayloadSize,
			"received_at":  record.Webhook.ReceivedAt.UTC().Format(time.RFC3339Nano),
		}
	}
	return payload
}