package cmd

import (
	"context"
	"fmt"
	"os"
	"sync"
	"time"

	tea "github.com/charmbracelet/bubbletea"
	"github.com/opencode-ai/opencode/internal/app"
	"github.com/opencode-ai/opencode/internal/config"
	"github.com/opencode-ai/opencode/internal/db"
	"github.com/opencode-ai/opencode/internal/llm/agent"
	"github.com/opencode-ai/opencode/internal/logging"
	"github.com/opencode-ai/opencode/internal/pubsub"
	"github.com/opencode-ai/opencode/internal/tui"
	"github.com/opencode-ai/opencode/internal/version"
	zone "github.com/lrstanley/bubblezone"
	"github.com/spf13/cobra"
)

var rootCmd = &cobra.Command{
	Use:   "OpenCode",
	Short: "A terminal AI assistant for software development",
	Long: `OpenCode is a powerful terminal-based AI assistant that helps with software development tasks.
It provides an interactive chat interface with AI capabilities, code analysis, and LSP integration
to assist developers in writing, debugging, and understanding code directly from the terminal.`,
	RunE: func(cmd *cobra.Command, args []string) error {
		// If the help flag is set, show the help message
		if cmd.Flag("help").Changed {
			cmd.Help()
			return nil
		}
		if cmd.Flag("version").Changed {
			fmt.Println(version.Version)
			return nil
		}

		// Load the config
		debug, _ := cmd.Flags().GetBool("debug")
		cwd, _ := cmd.Flags().GetString("cwd")
		if cwd != "" {
			err := os.Chdir(cwd)
			if err != nil {
				return fmt.Errorf("failed to change directory: %v", err)
			}
		}
		if cwd == "" {
			c, err := os.Getwd()
			if err != nil {
				return fmt.Errorf("failed to get current working directory: %v", err)
			}
			cwd = c
		}
		_, err := config.Load(cwd, debug)
		if err != nil {
			return err
		}

		// Connect DB, this will also run migrations
		conn, err := db.Connect()
		if err != nil {
			return err
		}

		// Create main context for the application
		ctx, cancel := context.WithCancel(context.Background())
		defer cancel()

		app, err := app.New(ctx, conn)
		if err != nil {
			logging.Error("Failed to create app: %v", err)
			return err
		}

		// Set up the TUI
		zone.NewGlobal()
		program := tea.NewProgram(
			tui.New(app),
			tea.WithAltScreen(),
			tea.WithMouseCellMotion(),
		)

		// Initialize MCP tools in the background
		initMCPTools(ctx, app)

		// Setup the subscriptions, this will send services events to the TUI
		ch, cancelSubs := setupSubscriptions(app, ctx)

		// Create a context for the TUI message handler
		tuiCtx, tuiCancel := context.WithCancel(ctx)
		var tuiWg sync.WaitGroup
		tuiWg.Add(1)

		// Set up message handling for the TUI
		go func() {
			defer tuiWg.Done()
			defer logging.RecoverPanic("TUI-message-handler", func() {
				attemptTUIRecovery(program)
			})

			for {
				select {
				case <-tuiCtx.Done():
					logging.Info("TUI message handler shutting down")
					return
				case msg, ok := <-ch:
					if !ok {
						logging.Info("TUI message channel closed")
						return
					}
					program.Send(msg)
				}
			}
		}()

		// Cleanup function for when the program exits
		cleanup := func() {
			// Shutdown the app
			app.Shutdown()

			// Cancel subscriptions first
			cancelSubs()

			// Then cancel TUI message handler
			tuiCancel()

			// Wait for TUI message handler to finish
			tuiWg.Wait()

			logging.Info("All goroutines cleaned up")
		}

		// Run the TUI
		result, err := program.Run()
		cleanup()

		if err != nil {
			logging.Error("TUI error: %v", err)
			return fmt.Errorf("TUI error: %v", err)
		}

		logging.Info("TUI exited with result: %v", result)
		return nil
	},
}

// attemptTUIRecovery tries to recover the TUI after a panic
func attemptTUIRecovery(program *tea.Program) {
	logging.Info("Attempting to recover TUI after panic")

	// We could try to restart the TUI or gracefully exit
	// For now, we'll just quit the program to avoid further issues
	program.Quit()
}

func initMCPTools(ctx context.Context, app *app.App) {
	go func() {
		defer logging.RecoverPanic("MCP-goroutine", nil)

		// Create a context with timeout for the initial MCP tools fetch
		ctxWithTimeout, cancel := context.WithTimeout(ctx, 30*time.Second)
		defer cancel()

		// Set this up once with proper error handling
		agent.GetMcpTools(ctxWithTimeout, app.Permissions)
		logging.Info("MCP message handling goroutine exiting")
	}()
}

func setupSubscriber[T any](
	ctx context.Context,
	wg *sync.WaitGroup,
	name string,
	subscriber func(context.Context) <-chan pubsub.Event[T],
	outputCh chan<- tea.Msg,
) {
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer logging.RecoverPanic(fmt.Sprintf("subscription-%s", name), nil)

		subCh := subscriber(ctx)

		for {
			select {
			case event, ok := <-subCh:
				if !ok {
					logging.Info("subscription channel closed", "name", name)
					return
				}

				var msg tea.Msg = event

				select {
				case outputCh <- msg:
				case <-time.After(2 * time.Second):
					logging.Warn("message dropped due to slow consumer", "name", name)
				case <-ctx.Done():
					logging.Info("subscription cancelled", "name", name)
					return
				}
			case <-ctx.Done():
				logging.Info("subscription cancelled", "name", name)
				return
			}
		}
	}()
}

func setupSubscriptions(app *app.App, parentCtx context.Context) (chan tea.Msg, func()) {
	ch := make(chan tea.Msg, 100)

	wg := sync.WaitGroup{}
	ctx, cancel := context.WithCancel(parentCtx) // Inherit from parent context

	setupSubscriber(ctx, &wg, "logging", logging.Subscribe, ch)
	setupSubscriber(ctx, &wg, "sessions", app.Sessions.Subscribe, ch)
	setupSubscriber(ctx, &wg, "messages", app.Messages.Subscribe, ch)
	setupSubscriber(ctx, &wg, "permissions", app.Permissions.Subscribe, ch)

	cleanupFunc := func() {
		logging.Info("Cancelling all subscriptions")
		cancel() // Signal all goroutines to stop

		waitCh := make(chan struct{})
		go func() {
			defer logging.RecoverPanic("subscription-cleanup", nil)
			wg.Wait()
			close(waitCh)
		}()

		select {
		case <-waitCh:
			logging.Info("All subscription goroutines completed successfully")
			close(ch) // Only close after all writers are confirmed done
		case <-time.After(5 * time.Second):
			logging.Warn("Timed out waiting for some subscription goroutines to complete")
			close(ch)
		}
	}
	return ch, cleanupFunc
}

func Execute() {
	err := rootCmd.Execute()
	if err != nil {
		os.Exit(1)
	}
}

func init() {
	rootCmd.Flags().BoolP("help", "h", false, "Help")
	rootCmd.Flags().BoolP("version", "v", false, "Version")
	rootCmd.Flags().BoolP("debug", "d", false, "Debug")
	rootCmd.Flags().StringP("cwd", "c", "", "Current working directory")
}
