// plexum-fabric-channel-plugin is the Plexum channel plugin that
// connects Plexum agents to a Fabric guild as members.
//
// F-1 (current): identity load, channel config discovery, REST send,
// agentLogin handshake. Plugin advertises channels via manifest +
// reads channels/<name>.json for the Plexum-channel → Fabric-channel
// mapping. The `send` outbound tool posts via Fabric REST.
//
// F-2+ (deferred): socket.io inbound, wakeup gating, token refresh,
// presence sync, sub-discussion, MCP tool surface (~15 tools from
// the openclaw plugin's tools.ts), attachments, channel canvas.
package main

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"os"
	"path/filepath"
	"sync"
	"time"

	plugin "git.hangman-lab.top/hzhang/Plexum-sdk-go/plugin"

	"git.hangman-lab.top/hzhang/Plexum-fabric-channel-plugin/internal/config"
	"git.hangman-lab.top/hzhang/Plexum-fabric-channel-plugin/internal/fabric"
	"git.hangman-lab.top/hzhang/Plexum-fabric-channel-plugin/internal/identity"
	"git.hangman-lab.top/hzhang/Plexum-fabric-channel-plugin/internal/inbound"
	"git.hangman-lab.top/hzhang/Plexum-fabric-channel-plugin/internal/tokens"
)

// HostConfig is the plugin's own config at
// <profile>/plugins/plexum-fabric-channel/config.json:
//
//	{
//	  "center_api_base": "http://localhost:7001/api"
//	}
type HostConfig struct {
	CenterAPIBase string `json:"center_api_base"`
}

type fabricPlugin struct {
	host plugin.HostAPI

	cfgPath    string
	cfg        HostConfig
	identities *identity.Registry
	bindings   []config.FabricBinding
	byFabric   config.ByFabricChannel
	client     *fabric.Client
	tokens     *tokens.Cache

	// Goroutine handle for the inbound supervisor. Cancelled on
	// plugin shutdown (we don't have an explicit shutdown signal in
	// the SDK today; rely on subprocess kill).
	inboundCancel context.CancelFunc
	inboundDone   chan struct{}

	// Legacy field — kept only for back-compat with non-tokens code
	// paths during the F-1 → F-2 refactor; safe to remove once nothing
	// else references it. Not used anymore.
	sessMu   sync.Mutex
	sessions map[string]*fabric.Session
}

func (p *fabricPlugin) Manifest() plugin.Manifest {
	// Manifest channels are populated dynamically from channels/*.json
	// at startup: the operator adds a channels/<name>.json + restarts
	// the gateway, and the matching ChannelContract entry surfaces here.
	// Both halves needed because Plexum's host registry reads the
	// manifest's channel names too.
	channels := p.dynamicChannelContracts()
	return plugin.Manifest{
		Name:       config.PluginName,
		Version:    "0.1.0",
		Activation: plugin.ActivationLazy,
		Executable: "plexum-fabric-channel-plugin",
		Contracts: plugin.Contracts{
			Channels: channels,
			Tools: []plugin.ToolContract{
				{
					Name:        "send",
					Description: "Post a plain-text message to the bound Fabric channel as the agent user.",
					InputSchema: json.RawMessage(`{
						"type": "object",
						"properties": {
							"channel_name": {"type": "string"},
							"session_id":   {"type": "string"},
							"message":      {"type": "string"}
						},
						"required": ["channel_name", "message"]
					}`),
				},
			},
		},
	}
}

func (p *fabricPlugin) dynamicChannelContracts() []plugin.ChannelContract {
	// Read channels/*.json from <profile>/channels and surface every
	// `plugin: plexum-fabric-channel` entry as a ChannelContract.
	profileRoot := os.Getenv("PLEXUM_PROFILE_ROOT")
	if profileRoot == "" {
		home, _ := os.UserHomeDir()
		profileRoot = filepath.Join(home, ".plexum")
	}
	bindings, err := config.Load(filepath.Join(profileRoot, "channels"))
	if err != nil {
		// Logged later in Init; manifest call can't itself reach a logger.
		return nil
	}
	out := make([]plugin.ChannelContract, 0, len(bindings))
	for _, b := range bindings {
		out = append(out, plugin.ChannelContract{
			Name: b.PlexumChannelName, OutboundTool: "send",
		})
	}
	return out
}

func (p *fabricPlugin) Init(ctx context.Context, host plugin.HostAPI) error {
	p.host = host
	p.sessions = map[string]*fabric.Session{}

	profileRoot := os.Getenv("PLEXUM_PROFILE_ROOT")
	if profileRoot == "" {
		home, _ := os.UserHomeDir()
		profileRoot = filepath.Join(home, ".plexum")
	}

	// Plugin-private config.
	p.cfgPath = filepath.Join(profileRoot, "plugins", config.PluginName, "config.json")
	raw, err := os.ReadFile(p.cfgPath)
	if err != nil && !errors.Is(err, os.ErrNotExist) {
		return fmt.Errorf("read %s: %w", p.cfgPath, err)
	}
	if len(raw) > 0 {
		if err := json.Unmarshal(raw, &p.cfg); err != nil {
			return fmt.Errorf("parse %s: %w", p.cfgPath, err)
		}
	}
	if p.cfg.CenterAPIBase == "" {
		p.cfg.CenterAPIBase = "http://localhost:7001/api"
	}
	p.client = fabric.New(p.cfg.CenterAPIBase)

	// Identity.
	idPath := filepath.Join(profileRoot, identity.FileName)
	p.identities, err = identity.Open(idPath)
	if err != nil {
		return fmt.Errorf("identity: %w", err)
	}

	// Channel bindings.
	p.bindings, err = config.Load(filepath.Join(profileRoot, "channels"))
	if err != nil {
		return fmt.Errorf("channel bindings: %w", err)
	}
	p.byFabric = config.Index(p.bindings)

	// Token cache: re-login per agent on TTL miss (8min default).
	p.tokens = tokens.New(0, func(loginCtx context.Context, agentID string) (*fabric.Session, error) {
		entry := p.identities.Lookup(agentID)
		if entry == nil || !entry.Enabled {
			return nil, fmt.Errorf("agent %s: no enabled identity", agentID)
		}
		return p.client.AgentLogin(loginCtx, entry.FabricAPIKey)
	})

	host.Log("info", "fabric channel plugin initialized", map[string]any{
		"center":            p.cfg.CenterAPIBase,
		"identity_path":     idPath,
		"channels_loaded":   len(p.bindings),
		"identities_loaded": len(p.identities.AgentIDs()),
	})

	// Warm sessions (early bad-key detection).
	if err := p.warmSessions(ctx); err != nil {
		host.Log("warn", "fabric warm-sessions had errors",
			map[string]any{"err": err.Error()})
	}

	// Phase F-2: start the inbound supervisor in a goroutine. Lives
	// until p.inboundCancel fires (currently never — SDK has no
	// shutdown hook; subprocess kill is the only stop signal).
	if len(p.bindings) > 0 {
		ctxBg, cancel := context.WithCancel(context.Background())
		p.inboundCancel = cancel
		p.inboundDone = make(chan struct{})
		notifier := func(channelName, message, sessionID string) {
			p.host.EmitNotification("notifications/plexum/channel/inbound", map[string]any{
				"channel_name": channelName,
				"message":      message,
				"session_id":   sessionID,
			})
		}
		// slog wrapping plugin.HostAPI.Log isn't worth the indirection
		// here; use a discard-style adapter that pipes WARN/INFO to
		// the host log.
		logger := slog.New(&hostLogHandler{host: host, level: slog.LevelInfo})
		sup := inbound.New(p.client, p.tokens, p.bindings, notifier, logger)
		go func() {
			defer close(p.inboundDone)
			if err := sup.Run(ctxBg); err != nil {
				host.Log("warn", "inbound supervisor exited", map[string]any{"err": err.Error()})
			}
		}()
		host.Log("info", "fabric inbound supervisor started",
			map[string]any{"agents": sup.AgentIDs, "bindings": len(p.bindings)})
	}

	return nil
}

// hostLogHandler is a tiny slog.Handler that forwards records to the
// plugin's HostAPI.Log. inbound + supervisor use slog for structured
// logging; this bridges to the host's log notification stream.
type hostLogHandler struct {
	host  plugin.HostAPI
	level slog.Level
}

func (h *hostLogHandler) Enabled(_ context.Context, l slog.Level) bool { return l >= h.level }
func (h *hostLogHandler) Handle(_ context.Context, r slog.Record) error {
	attrs := make(map[string]any, r.NumAttrs())
	r.Attrs(func(a slog.Attr) bool {
		attrs[a.Key] = a.Value.Any()
		return true
	})
	h.host.Log(levelString(r.Level), r.Message, attrs)
	return nil
}
func (h *hostLogHandler) WithAttrs(_ []slog.Attr) slog.Handler { return h }
func (h *hostLogHandler) WithGroup(_ string) slog.Handler      { return h }

func levelString(l slog.Level) string {
	switch {
	case l >= slog.LevelError:
		return "error"
	case l >= slog.LevelWarn:
		return "warn"
	case l >= slog.LevelInfo:
		return "info"
	default:
		return "debug"
	}
}

func (p *fabricPlugin) warmSessions(ctx context.Context) error {
	// Which agents appear as a binding's AgentID?
	agentsNeeded := map[string]bool{}
	for _, b := range p.bindings {
		agentsNeeded[b.AgentID] = true
	}
	enabled := p.identities.EnabledEntries()

	var firstErr error
	for agentID := range agentsNeeded {
		if _, ok := enabled[agentID]; !ok {
			err := fmt.Errorf("agent %s has channels but no identity (run plexum-fabric-register --agent-id %s --api-key ...)",
				agentID, agentID)
			p.host.Log("warn", err.Error(), nil)
			if firstErr == nil {
				firstErr = err
			}
			continue
		}
		sess, err := p.tokens.Get(ctx, agentID)
		if err != nil {
			p.host.Log("warn", "fabric agent warm failed",
				map[string]any{"agent": agentID, "err": err.Error()})
			if firstErr == nil {
				firstErr = err
			}
			continue
		}
		p.host.Log("info", "fabric session warm", map[string]any{
			"agent": agentID, "fabric_user": sess.User.Email,
			"guilds": len(sess.Guilds),
		})
	}
	return firstErr
}

// CallTool handles the "send" outbound tool.
func (p *fabricPlugin) CallTool(ctx context.Context, name string, input json.RawMessage) (plugin.ToolResult, error) {
	if name != "send" {
		return plugin.ToolResult{}, fmt.Errorf("unknown tool: %s", name)
	}
	var args struct {
		ChannelName string `json:"channel_name"`
		SessionID   string `json:"session_id"`
		Message     string `json:"message"`
	}
	if err := json.Unmarshal(input, &args); err != nil {
		return plugin.ToolResult{}, fmt.Errorf("parse args: %w", err)
	}
	if args.ChannelName == "" {
		return errResult("channel_name required"), nil
	}
	p.host.Log("info", "fabric send", map[string]any{
		"channel_name": args.ChannelName, "len": len(args.Message),
	})

	// Find the binding for this plexum channel name.
	var binding *config.FabricBinding
	for i := range p.bindings {
		if p.bindings[i].PlexumChannelName == args.ChannelName {
			binding = &p.bindings[i]
			break
		}
	}
	if binding == nil {
		return errResult("unknown plexum channel: " + args.ChannelName), nil
	}

	// Resolve the bound agent's session (may need refresh — F-2 will
	// add a proper TTL + background refresh; for F-1 we re-login lazily
	// if the cache is empty).
	sess, err := p.sessionFor(ctx, binding.AgentID)
	if err != nil {
		return errResult("session for agent " + binding.AgentID + ": " + err.Error()), nil
	}

	// Pick the guild endpoint + token for the target guild_node_id.
	var (
		endpoint string
		token    string
	)
	for _, g := range sess.Guilds {
		if g.NodeID == binding.FabricGuildNodeID {
			endpoint = g.Endpoint
			break
		}
	}
	for _, t := range sess.GuildAccessTokens {
		if t.GuildNodeID == binding.FabricGuildNodeID {
			token = t.Token
			break
		}
	}
	if endpoint == "" || token == "" {
		return errResult(fmt.Sprintf("agent %s has no access to guild %s",
			binding.AgentID, binding.FabricGuildNodeID)), nil
	}

	if err := p.client.PostMessage(ctx, endpoint, token,
		binding.FabricChannelID, args.Message, sess.User.ID); err != nil {
		return errResult("post: " + err.Error()), nil
	}
	return plugin.NewTextResult("sent"), nil
}

func (p *fabricPlugin) sessionFor(ctx context.Context, agentID string) (*fabric.Session, error) {
	loginCtx, cancel := context.WithTimeout(ctx, 15*time.Second)
	defer cancel()
	return p.tokens.Get(loginCtx, agentID)
}

func errResult(msg string) plugin.ToolResult {
	return plugin.ToolResult{
		Content: []plugin.ContentBlock{{Type: "text", Text: msg}},
		IsError: true,
	}
}

func main() {
	if err := plugin.Serve(&fabricPlugin{}); err != nil {
		fmt.Fprintf(os.Stderr, "plexum-fabric-channel-plugin: %v\n", err)
		os.Exit(1)
	}
}