package app

import (
	"bufio"
	"context"
	"fmt"
	"os"
	"strings"

	"agentu/internal/agent"
	"agentu/internal/session"
	"agentu/internal/skills"
)

func repl(ctx context.Context, assistant *agent.Agent, modelManager *session.Manager) error {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]byte, 0, 64*1024), 1024*1024)

	fmt.Println("agentu")
	fmt.Println("Type /exit to quit, /clear to reset context, /compact to compress context, /btw <question> for a side question.")
	for {
		fmt.Print("> ")
		if !scanner.Scan() {
			if err := scanner.Err(); err != nil {
				return err
			}
			fmt.Println()
			printExitSession(modelManager)
			return nil
		}

		input := strings.TrimSpace(scanner.Text())
		fields := strings.Fields(input)
		switch input {
		case "":
			continue
		case "/exit", "/quit":
			printExitSession(modelManager)
			return nil
		case "/clear":
			assistant.Clear()
			fmt.Println("context cleared")
			continue
		case "/compact":
			if err := assistant.Compact(ctx); err != nil {
				fmt.Fprintln(os.Stderr, "compact error:", err)
			} else {
				fmt.Println("context compacted")
				if modelManager != nil {
					_ = modelManager.Save()
				}
			}
			continue
		}
		if len(fields) > 0 && fields[0] == "/btw" {
			question := strings.TrimSpace(strings.TrimPrefix(input, "/btw"))
			if question == "" {
				fmt.Fprintln(os.Stderr, "usage: /btw <question>")
				continue
			}
			fmt.Print("[btw] ")
			if err := assistant.BTW(ctx, question, os.Stdout); err != nil {
				fmt.Fprintln(os.Stderr, "\nbtw error:", err)
			} else {
				fmt.Println()
			}
			continue
		}
		if input == "/skills" || input == "/skills list" {
			items, err := skills.LoadGlobal()
			if err != nil {
				fmt.Fprintln(os.Stderr, "skills error:", err)
			} else {
				fmt.Println(skills.FormatList(items))
			}
			continue
		}
		if len(fields) >= 3 && fields[0] == "/skills" && fields[1] == "install" {
			result, err := skills.InstallGlobal(ctx, strings.Join(fields[2:], " "))
			if err != nil {
				fmt.Fprintln(os.Stderr, "skills error:", err)
			} else {
				assistant.AddSystemInstructions(skills.FormatForSystemPrompt([]skills.Skill{result.Skill}))
				fmt.Printf("installed skill %q; active in this conversation\n", result.Skill.Name)
			}
			continue
		}

		if err := assistant.RunTurn(ctx, input, os.Stdout, os.Stderr); err != nil {
			fmt.Fprintln(os.Stderr, "\nerror:", err)
		}
		_ = modelManager.Save()
		fmt.Println()
	}
}