package main

import (
	"context"
	"flag"
	"log"
	"os"
	"os/signal"
	"path/filepath"
	"slices"
	"syscall"
	"time"

	"github.com/kami/hexis/internal/api"
	"github.com/kami/hexis/internal/domain"
	"github.com/kami/hexis/internal/execution"
	"github.com/kami/hexis/internal/mcp"
	"github.com/kami/hexis/internal/nexusclient"
	"github.com/kami/hexis/internal/provider"
	"github.com/kami/hexis/internal/storage"
)

func main() {
	var httpAddr string
	var dataDir string
	var mcpMode bool
	var workspaceURL string
	var workspaceAllowlist string
	var nexusURL string

	flag.StringVar(&httpAddr, "http", "", "HTTP listen address (default localhost:9741)")
	flag.StringVar(&dataDir, "data", "", "Data directory for SQLite database")
	flag.BoolVar(&mcpMode, "mcp", false, "Run in MCP stdio mode")
	flag.StringVar(&workspaceURL, "workspace-url", "", "Workspace MCP HTTP API URL (e.g. http://localhost:9930)")
	flag.StringVar(&workspaceAllowlist, "workspace-allowlist", "", "Path to workspace tool allowlist YAML")
	flag.StringVar(&nexusURL, "nexus", "", "Nexus base URL for hexis.resolve_target (default http://localhost:9740)")
	flag.Parse()

	if dataDir == "" {
		dataDir = filepath.Join(os.Getenv("HOME"), ".local", "share", "hexis")
	}
	if httpAddr == "" {
		httpAddr = "localhost:9741"
	}
	if workspaceAllowlist == "" {
		workspaceAllowlist = filepath.Join(dataDir, "workspace-allowlist.yaml")
	}
	if workspaceURL == "" {
		workspaceURL = os.Getenv("WORKSPACE_MCP_URL")
	}
	if nexusURL == "" {
		nexusURL = os.Getenv("HEXIS_NEXUS_URL")
	}
	if nexusURL == "" {
		nexusURL = "http://localhost:9740"
	}

	dbPath := filepath.Join(dataDir, "hexis.db")

	store, err := storage.Open(dbPath)
	if err != nil {
		log.Fatalf("open storage: %v", err)
	}
	defer store.Close()

	reg := provider.NewRegistry()

	// Register workspace MCP provider if configured
	if workspaceURL != "" {
		allowlist, err := provider.LoadToolAllowlist(workspaceAllowlist)
		if err != nil {
			log.Fatalf("load workspace allowlist: %v", err)
		}
		wsProvider := provider.NewWorkspaceMCPProvider(workspaceURL, allowlist)
		reg.Register(wsProvider)

		tools, err := wsProvider.DiscoverTools()
		if err != nil {
			log.Printf("warning: workspace MCP discovery failed: %v", err)
		} else {
			log.Printf("discovered %d workspace tools, %d in allowlist", len(tools), len(allowlist.Tools))
		}

		// Register workspace capabilities, reconciling existing rows so that
		// allowlist edits (risk tier, target type, enabled) reach a database
		// that was populated by an earlier build.
		for _, cap := range wsProvider.BuildCapabilities() {
			existing, err := store.GetCapability(cap.ID)
			if err == nil && existing != nil {
				if !capabilityMatches(existing, &cap) {
					merged := cap
					merged.CreatedAt = existing.CreatedAt
					merged.UpdatedAt = time.Now().UTC()
					merged.Attributes = existing.Attributes
					// UpdateCapability is optimistically concurrent: it matches
					// on the current version and bumps it.
					merged.Version = existing.Version
					if err := store.UpdateCapability(&merged); err != nil {
						log.Printf("warning: reconcile capability %s: %v", cap.Name, err)
					} else {
						log.Printf("reconciled capability: %s -> %s (version %d)", merged.Name, merged.Operation, merged.Version)
					}
				}
				continue
			}
			if err := store.CreateCapability(&cap); err != nil {
				log.Printf("warning: register capability %s: %v", cap.Name, err)
			} else {
				log.Printf("registered capability: %s -> %s", cap.Name, cap.Operation)
			}
		}
	}

	// Nexus is the sole authority on entity identity: Hexis refuses any
	// target it cannot confirm exists there (ECOSYSTEM-SPEC.md §4.3, "Hexis
	// never accepts a free-text target. Ever."). If Nexus is down, executes
	// fail closed with 503 rather than accepting the target on trust.
	nexus := nexusclient.New(nexusURL)
	engine := execution.New(store, reg, execution.WithEntityLookup(nexus))

	if mcpMode {
		log.Printf("starting MCP stdio adapter")
		adapter := mcp.New(store, engine, nexus)
		if err := adapter.ServeStdio(); err != nil {
			log.Fatalf("MCP error: %v", err)
		}
		return
	}

	// Shared bearer token for /api/v1/. Required: the HTTP surface can start
	// and stop containers, and it is reverse-proxied on a public hostname.
	apiToken := os.Getenv("HEXIS_API_TOKEN")
	if apiToken == "" {
		log.Fatalf("HEXIS_API_TOKEN is not set: refusing to serve /api/v1/ unauthenticated")
	}

	srv := api.NewServer(store, engine, apiToken)

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	go func() {
		log.Printf("listening on http %s", httpAddr)
		if err := srv.ListenHTTP(httpAddr); err != nil {
			log.Printf("http error: %v", err)
		}
	}()

	sig := make(chan os.Signal, 1)
	signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
	<-sig

	log.Println("shutting down...")
	srv.Shutdown(ctx)
	log.Println("stopped")
}

// capabilityMatches reports whether the stored capability already carries every
// derived field, ignoring bookkeeping (timestamps, version, attributes).
func capabilityMatches(stored, derived *domain.Capability) bool {
	return stored.Name == derived.Name &&
		stored.Description == derived.Description &&
		slices.Equal(stored.TargetTypes, derived.TargetTypes) &&
		stored.TargetEntityID == derived.TargetEntityID &&
		stored.Provider == derived.Provider &&
		stored.Operation == derived.Operation &&
		stored.Risk == derived.Risk &&
		stored.ReadOnly == derived.ReadOnly &&
		stored.ExpectedSideEffects == derived.ExpectedSideEffects &&
		stored.RequiresConfirmation == derived.RequiresConfirmation &&
		stored.Enabled == derived.Enabled &&
		stored.TimeoutSeconds == derived.TimeoutSeconds
}