package actor

import (
	"context"
	"fmt"
	"io"
	"strings"

	"github.com/orca/orca/pkg/bus"
	"github.com/orca/orca/pkg/llm"
)

type SubAgent struct {
	*BaseAgent
	llmBackend   llm.LLM
	systemPrompt string
	role         string
	streamWriter io.Writer
}

type SubAgentOption func(*SubAgent)

func WithSubAgentSystemPrompt(prompt string) SubAgentOption {
	return func(a *SubAgent) {
		a.systemPrompt = prompt
	}
}

func WithSubAgentRole(role string) SubAgentOption {
	return func(a *SubAgent) {
		a.role = role
	}
}

func WithSubAgentStreamWriter(w io.Writer) SubAgentOption {
	return func(a *SubAgent) {
		a.streamWriter = w
	}
}

func NewSubAgent(id string, llmBackend llm.LLM, opts ...SubAgentOption) *SubAgent {
	sa := &SubAgent{
		BaseAgent:    NewBaseAgent(id, "subagent"),
		llmBackend:   llmBackend,
		systemPrompt: "你是一个专业的AI助手。",
		role:         "assistant",
	}

	for _, opt := range opts {
		opt(sa)
	}

	sa.SetHandler(sa.handleMessage)

	if err := sa.Start(); err != nil {
		panic(fmt.Sprintf("subagent: failed to start %s: %v", id, err))
	}

	return sa
}

func (sa *SubAgent) Role() string {
	return sa.role
}

func (sa *SubAgent) SystemPrompt() string {
	return sa.systemPrompt
}

func (sa *SubAgent) SetStreamWriter(w io.Writer) {
	sa.streamWriter = w
}

func (sa *SubAgent) handleMessage(ctx context.Context, msg bus.Message) (bus.Message, error) {
	switch msg.Type {
	case bus.MsgTypeTaskRequest:
		return sa.handleTask(ctx, msg)
	case bus.MsgTypeSystem:
		return sa.handleSystem(ctx, msg)
	default:
		return bus.Message{}, fmt.Errorf("subagent %s: unsupported message type %s", sa.ID(), msg.Type)
	}
}

func (sa *SubAgent) handleTask(ctx context.Context, msg bus.Message) (bus.Message, error) {
	messages := []llm.Message{
		{
			Role:    "system",
			Content: sa.systemPrompt,
		},
		{
			Role:    "user",
			Content: fmt.Sprintf("%v", msg.Content),
		},
	}

	content, err := sa.streamChat(ctx, messages)
	if err != nil {
		return bus.Message{}, fmt.Errorf("subagent %s: LLM call failed: %w", sa.ID(), err)
	}

	return bus.Message{
		ID:      msg.ID + "-response",
		Type:    bus.MsgTypeTaskResponse,
		From:    sa.ID(),
		To:      msg.From,
		Content: content,
		Metadata: map[string]string{
			"processed_by": sa.ID(),
			"agent_role":   sa.role,
		},
	}, nil
}

func (sa *SubAgent) streamChat(ctx context.Context, messages []llm.Message) (string, error) {
	var content strings.Builder

	if sa.streamWriter != nil {
		fmt.Fprintf(sa.streamWriter, "\n[%s] ", sa.ID())
	}

	err := sa.llmBackend.Stream(ctx, messages, func(chunk string) error {
		content.WriteString(chunk)
		if sa.streamWriter != nil {
			fmt.Fprint(sa.streamWriter, chunk)
		}
		return nil
	})

	if err != nil {
		return "", err
	}

	if sa.streamWriter != nil {
		fmt.Fprintln(sa.streamWriter)
	}

	return content.String(), nil
}

func (sa *SubAgent) handleSystem(ctx context.Context, msg bus.Message) (bus.Message, error) {
	return bus.Message{
		ID:      msg.ID + "-ack",
		Type:    bus.MsgTypeSystem,
		From:    sa.ID(),
		To:      msg.From,
		Content: fmt.Sprintf("subagent %s acknowledged", sa.ID()),
	}, nil
}