// Package lspool provides LS-mode integration for the antigravity gateway.
//
// When LS mode is enabled (via ANTIGRAVITY_LS_MODE=true), requests to
// streamGenerateContent are routed through a real Language Server instance
// instead of directly to cloudcode-pa. This provides:
//
//   - Authentic TLS fingerprint (Google's own Go binary)
//   - Real session management and Heartbeat
//   - Indistinguishable from a real IDE instance
//
// To enable: set environment variable ANTIGRAVITY_LS_MODE=true
// To configure: set ANTIGRAVITY_APP_ROOT to the AntiGravity.app path
package lspool

import (
	"log/slog"
	"os"
	"strings"
	"sync"

	"github.com/Wei-Shaw/sub2api/internal/config"
)

var (
	globalBackend  Backend
	globalPoolOnce sync.Once
	lsModeEnabled  bool
)

func init() {
	lsModeEnabled = os.Getenv("ANTIGRAVITY_LS_MODE") == "true"
}

// IsLSModeEnabled returns whether LS mode is active
func IsLSModeEnabled() bool {
	return lsModeEnabled
}

const (
	LSStrategyDirect   = "direct"
	LSStrategyJSParity = "js-parity"
)

// CurrentLSStrategy returns the active LS routing strategy.
// Unknown values are treated as "direct" for safety.
func CurrentLSStrategy() string {
	switch strings.ToLower(strings.TrimSpace(os.Getenv("ANTIGRAVITY_LS_STRATEGY"))) {
	case "", LSStrategyDirect:
		return LSStrategyDirect
	case LSStrategyJSParity:
		return LSStrategyJSParity
	default:
		return LSStrategyDirect
	}
}

// GlobalPool returns the singleton LS pool instance
// Creates it on first call if LS mode is enabled
func GlobalPool(cfg *config.Config) Backend {
	if !lsModeEnabled {
		return nil
	}
	globalPoolOnce.Do(func() {
		manager, err := NewWorkerManagerFromConfig(cfg)
		if err != nil {
			slog.Default().Error("failed to initialize LS worker manager", "err", err)
			return
		}
		globalBackend = manager
	})
	return globalBackend
}

// Shutdown closes the global pool
func Shutdown() {
	if globalBackend != nil {
		globalBackend.Close()
	}
}

// StatusInfo returns the current LS pool status for diagnostics
func StatusInfo() map[string]any {
	info := map[string]any{
		"ls_mode_enabled": lsModeEnabled,
		"build":           "enhanced",
		"user_agent":      "antigravity/1.107.0",
	}
	if lsModeEnabled && globalBackend != nil {
		stats := globalBackend.Stats()
		info["pool_total"] = stats["total"]
		info["pool_active"] = stats["active"]
	}
	return info
}