// SPDX-License-Identifier: EUPL-1.2

// Package core is a dependency injection and service lifecycle framework for Go.
// This file defines the Core struct, accessors, and IPC/error wrappers.

package core

import (
	"context"
	"os"
	"sync"
	"sync/atomic"
)

// --- Core Struct ---

// Core is the central application object that manages services, assets, and communication.
type Core struct {
	options *Options    // c.Options()        — Input configuration used to create this Core
	app     *App        // c.App()            — Application identity + optional GUI runtime
	data    *Data       // c.Data()           — Embedded/stored content from packages
	drive   *Drive      // c.Drive()          — Resource handle registry (transports)
	fs      *Fs         // c.Fs()             — Local filesystem I/O (sandboxable)
	config  *Config     // c.Config()         — Configuration, settings, feature flags
	error   *ErrorPanic // c.Error()          — Panic recovery and crash reporting
	log     *ErrorLog   // c.Log()            — Structured logging + error wrapping
	// cli accessed via ServiceFor[*Cli](c, "cli")
	commands *CommandRegistry // c.Command("path")  — Command tree
	services *ServiceRegistry // c.Service("name")  — Service registry
	lock     *Lock            // c.Lock("name")     — Named mutexes
	ipc      *Ipc             // c.IPC()            — Message bus for IPC
	info     *SysInfo         // c.Env("key")        — Read-only system/environment information
	i18n     *I18n            // c.I18n()           — Internationalisation and locale collection

	context       context.Context
	cancel        context.CancelFunc
	taskIDCounter atomic.Uint64
	waitGroup     sync.WaitGroup
	shutdown      atomic.Bool
}

// --- Accessors ---

func (c *Core) Options() *Options        { return c.options }
func (c *Core) App() *App                { return c.app }
func (c *Core) Data() *Data              { return c.data }
func (c *Core) Drive() *Drive            { return c.drive }
func (c *Core) Fs() *Fs                  { return c.fs }
func (c *Core) Config() *Config          { return c.config }
func (c *Core) Error() *ErrorPanic       { return c.error }
func (c *Core) Log() *ErrorLog           { return c.log }
func (c *Core) Cli() *Cli {
	cl, _ := ServiceFor[*Cli](c, "cli")
	return cl
}
func (c *Core) IPC() *Ipc                { return c.ipc }
func (c *Core) I18n() *I18n              { return c.i18n }
func (c *Core) Env(key string) string    { return Env(key) }
func (c *Core) Context() context.Context { return c.context }
func (c *Core) Core() *Core              { return c }

// --- Lifecycle ---

// RunE starts all services, runs the CLI, then shuts down.
// Returns an error instead of calling os.Exit — let main() handle the exit.
// ServiceShutdown is always called via defer, even on startup failure or panic.
//
//	if err := c.RunE(); err != nil {
//	    os.Exit(1)
//	}
func (c *Core) RunE() error {
	defer c.ServiceShutdown(context.Background())

	r := c.ServiceStartup(c.context, nil)
	if !r.OK {
		if err, ok := r.Value.(error); ok {
			return err
		}
		return E("core.Run", "startup failed", nil)
	}

	if cli := c.Cli(); cli != nil {
		r = cli.Run()
	}

	if !r.OK {
		if err, ok := r.Value.(error); ok {
			return err
		}
	}
	return nil
}

// Run starts all services, runs the CLI, then shuts down.
// Calls os.Exit(1) on failure. For error handling use RunE().
//
//	c := core.New(core.WithService(myService.Register))
//	c.Run()
func (c *Core) Run() {
	if err := c.RunE(); err != nil {
		Error(err.Error())
		os.Exit(1)
	}
}

// --- IPC (uppercase aliases) ---

func (c *Core) ACTION(msg Message) Result { return c.broadcast(msg) }
func (c *Core) QUERY(q Query) Result      { return c.Query(q) }
func (c *Core) QUERYALL(q Query) Result   { return c.QueryAll(q) }
func (c *Core) PERFORM(t Task) Result     { return c.Perform(t) }

// --- Error+Log ---

// LogError logs an error and returns the Result from ErrorLog.
func (c *Core) LogError(err error, op, msg string) Result {
	return c.log.Error(err, op, msg)
}

// LogWarn logs a warning and returns the Result from ErrorLog.
func (c *Core) LogWarn(err error, op, msg string) Result {
	return c.log.Warn(err, op, msg)
}

// Must logs and panics if err is not nil.
func (c *Core) Must(err error, op, msg string) {
	c.log.Must(err, op, msg)
}

// --- Registry Accessor ---

// RegistryOf returns a named registry for cross-cutting queries.
// Known registries: "services", "commands", "actions".
//
//	c.RegistryOf("services").Names()           // all service names
//	c.RegistryOf("actions").List("process.*")  // process capabilities
//	c.RegistryOf("commands").Len()             // command count
func (c *Core) RegistryOf(name string) *Registry[any] {
	// Bridge typed registries to untyped access for cross-cutting queries.
	// Each registry is wrapped in a read-only proxy.
	switch name {
	case "services":
		return registryProxy(c.services.Registry)
	case "commands":
		return registryProxy(c.commands.Registry)
	case "actions":
		return registryProxy(c.ipc.actions)
	default:
		return NewRegistry[any]() // empty registry for unknown names
	}
}

// registryProxy creates a read-only any-typed view of a typed registry.
// Copies current state — not a live view (avoids type parameter leaking).
func registryProxy[T any](src *Registry[T]) *Registry[any] {
	proxy := NewRegistry[any]()
	src.Each(func(name string, item T) {
		proxy.Set(name, item)
	})
	return proxy
}

// --- Global Instance ---