// github.com/cloudwego/eino/adk/chatmodel.go

type ToolsConfig struct {
    compose.ToolsNodeConfig

    // Names of the tools that will make agent return directly when the tool is called.
    // When multiple tools are called and more than one tool is in the return directly list, only the first one will be returned.
    ReturnDirectly map[string]bool
    
    // EmitInternalEvents indicates whether internal events from agentTool should be emitted
    // to the parent generator via a tool option injection at run-time.
    EmitInternalEvents bool
}

type ChatModelAgentConfig struct {
    // Name of the agent. Better be unique across all agents.
    Name string
    // Description of the agent's capabilities.
    // Helps other agents determine whether to transfer tasks to this agent.
    Description string
    // Instruction used as the system prompt for this agent.
    // Optional. If empty, no system prompt will be used.
    // Supports f-string placeholders for session values in default GenModelInput, for example:
    // "You are a helpful assistant. The current time is {Time}. The current user is {User}."
    // These placeholders will be replaced with session values for "Time" and "User".
    Instruction string

    Model model.ToolCallingChatModel

    ToolsConfig ToolsConfig

    // GenModelInput transforms instructions and input messages into the model's input format.
    // Optional. Defaults to defaultGenModelInput which combines instruction and messages.
    GenModelInput GenModelInput

    // Exit defines the tool used to terminate the agent process.
    // Optional. If nil, no Exit Action will be generated.
    // You can use the provided 'ExitTool' implementation directly.
    Exit tool.BaseTool

    // OutputKey stores the agent's response in the session.
    // Optional. When set, stores output via AddSessionValue(ctx, outputKey, msg.Content).
    OutputKey string

    // MaxIterations defines the upper limit of ChatModel generation cycles.
    // The agent will terminate with an error if this limit is exceeded.
    // Optional. Defaults to 20.
    MaxIterations int
    
    // ModelRetryConfig configures retry behavior for the ChatModel.
    // When set, the agent will automatically retry failed ChatModel calls
    // based on the configured policy.
    // Optional. If nil, no retry will be performed.
    ModelRetryConfig *ModelRetryConfig
}

type ToolsConfig struct {
    compose.ToolsNodeConfig

    // Names of the tools that will make agent return directly when the tool is called.
    // When multiple tools are called and more than one tool is in the return directly list, only the first one will be returned.
    ReturnDirectly map[string]bool
    
    // EmitInternalEvents indicates whether internal events from agentTool should be emitted
    // to the parent generator via a tool option injection at run-time.
    EmitInternalEvents bool
}

type GenModelInput func(ctx context.Context, instruction string, input *AgentInput) ([]Message, error)

type ExitTool struct{}

func (et ExitTool) Info(_ context.Context) (*schema.ToolInfo, error) {
    return ToolInfoExit, nil
}

func (et ExitTool) InvokableRun(ctx context.Context, argumentsInJSON string, _ ...tool.Option) (string, error) {
    type exitParams struct {
       FinalResult string `json:"final_result"`
    }

    params := &exitParams{}
    err := sonic.UnmarshalString(argumentsInJSON, params)
    if err != nil {
       return "", err
    }

    err = SendToolGenAction(ctx, "exit", NewExitAction())
    if err != nil {
       return "", err
    }

    return params.FinalResult, nil
}

iterator := agent.Run(ctx, input)
for {
    event, ok := iterator.Next()
    if !ok {
        break
    }
    
    if event.Err != nil {
        handleFinalError(event.Err)
        break
    }
    
    // Process streaming output
    if event.Output != nil && event.Output.MessageOutput.IsStreaming {
        stream := event.Output.MessageOutput.MessageStream
        for {
            msg, err := stream.Recv()
            if err == io.EOF {
                break  // Stream completed successfully
            }
            if err != nil {
                // Check if this error will be retried (more streams coming)
                var willRetry *adk.WillRetryError
                if errors.As(err, &willRetry) {
                    log.Printf("Attempt %d failed, retrying...", willRetry.RetryAttempt)
                    break  // Wait for next event with new stream
                }
                // Original error - won't retry, agent will stop and the next AgentEvent probably will be an error
                log.Printf("Final error (no retry): %v", err)
                break
            }
            // Display chunk to user
            displayChunk(msg)
        }
    }
}

const (
    TransferToAgentInstruction = `Available other agents: %s

Decision rule:
- If you're best suited for the question according to your description: ANSWER
- If another agent is better according its description: CALL '%s' function with their agent name

When transferring: OUTPUT ONLY THE FUNCTION CALL`
)

func genTransferToAgentInstruction(ctx context.Context, agents []Agent) string {
    var sb strings.Builder
    for _, agent := range agents {
       sb.WriteString(fmt.Sprintf("\n- Agent name: %s\n  Agent description: %s",
          agent.Name(ctx), agent.Description(ctx)))
    }

    return fmt.Sprintf(TransferToAgentInstruction, sb.String(), TransferToAgentToolName)
}

// github.com/cloudwego/eino/adk/agent_tool.go    

func NewAgentTool(_ context.Context, agent Agent, options ...AgentToolOption) tool.BaseTool

bookRecommender := NewBookRecommendAgent()
bookRecommendeTool := NewAgentTool(ctx, bookRecommender)

a, err := adk.NewChatModelAgent(ctx, &adk.ChatModelAgentConfig{
    // ...
    ToolsConfig: adk.ToolsConfig{
        ToolsNodeConfig: compose.ToolsNodeConfig{
            Tools: []tool.BaseTool{bookRecommendeTool},
        },
    },
})

import (
    "context"
    "log"

    "github.com/cloudwego/eino/components/tool"
    "github.com/cloudwego/eino/components/tool/utils"
)

type BookSearchInput struct {
    Genre     string `json:"genre" jsonschema:"description=Preferred book genre,enum=fiction,enum=sci-fi,enum=mystery,enum=biography,enum=business"`
    MaxPages  int    `json:"max_pages" jsonschema:"description=Maximum page length (0 for no limit)"`
    MinRating int    `json:"min_rating" jsonschema:"description=Minimum user rating (0-5 scale)"`
}

type BookSearchOutput struct {
    Books []string
}

func NewBookRecommender() tool.InvokableTool {
    bookSearchTool, err := utils.InferTool("search_book", "Search books based on user preferences", func(ctx context.Context, input *BookSearchInput) (output *BookSearchOutput, err error) {
       // search code
       // ...
       return &BookSearchOutput{Books: []string{"God's blessing on this wonderful world!"}}, nil
    })
    if err != nil {
       log.Fatalf("failed to create search book tool: %v", err)
    }
    return bookSearchTool
}

import (
    "context"
    "fmt"
    "log"
    "os"

    "github.com/cloudwego/eino-ext/components/model/openai"
    "github.com/cloudwego/eino/components/model"
)

func NewChatModel() model.ToolCallingChatModel {
    ctx := context.Background()
    apiKey := os.Getenv("OPENAI_API_KEY")
    openaiModel := os.Getenv("OPENAI_MODEL")

    cm, err := openai.NewChatModel(ctx, &openai.ChatModelConfig{
       APIKey: apiKey,
       Model:  openaiModel,
    })
    if err != nil {
       log.Fatal(fmt.Errorf("failed to create chatmodel: %w", err))
    }
    return cm
}

import (
    "context"
    "fmt"
    "log"

    "github.com/cloudwego/eino/adk"
    "github.com/cloudwego/eino/components/tool"
    "github.com/cloudwego/eino/compose"
)

func NewBookRecommendAgent() adk.Agent {
    ctx := context.Background()

    a, err := adk.NewChatModelAgent(ctx, &adk.ChatModelAgentConfig{
       Name:        "BookRecommender",
       Description: "An agent that can recommend books",
       Instruction: `You are an expert book recommender. Based on the user's request, use the "search_book" tool to find relevant books. Finally, present the results to the user.`,
       Model:       NewChatModel(),
       ToolsConfig: adk.ToolsConfig{
          ToolsNodeConfig: compose.ToolsNodeConfig{
             Tools: []tool.BaseTool{NewBookRecommender()},
          },
       },
    })
    if err != nil {
       log.Fatal(fmt.Errorf("failed to create chatmodel: %w", err))
    }

    return a
}

import (
    "context"
    "fmt"
    "log"
    "os"

    "github.com/cloudwego/eino/adk"

    "github.com/cloudwego/eino-examples/adk/intro/chatmodel/internal"
)

func main() {
    ctx := context.Background()
    a := internal.NewBookRecommendAgent()
    runner := adk.NewRunner(ctx, adk.RunnerConfig{
       Agent: a,
    })
    iter := runner.Query(ctx, "recommend a fiction book to me")
    for {
       event, ok := iter.Next()
       if !ok {
          break
       }
       if event.Err != nil {
          log.Fatal(event.Err)
       }
       msg, err := event.Output.MessageOutput.GetMessage()
       if err != nil {
          log.Fatal(err)
       }
       fmt.Printf("\nmessage:\n%v\n======", msg)
    }
}

message:
assistant: 
tool_calls:
{Index:<nil> ID:call_o2It087hoqj8L7atzr70EnfG Type:function Function:{Name:search_book Arguments:{"genre":"fiction","max_pages":0,"min_rating":0}} Extra:map[]}

finish_reason: tool_calls
usage: &{140 24 164}
======


message:
tool: {"Books":["God's blessing on this wonderful world!"]}
tool_call_id: call_o2It087hoqj8L7atzr70EnfG
tool_call_name: search_book
======


message:
assistant: I recommend the fiction book "God's blessing on this wonderful world!". It's a great choice for readers looking for an exciting story. Enjoy your reading!
finish_reason: stop
usage: &{185 31 216}
======

// github.com/cloudwego/eino/adk/interrupt.go

func NewInterruptAndRerunErr(extra any) error

import (
    "github.com/cloudwego/eino/components/tool"
)

type askForClarificationOptions struct {
    NewInput *string
}

func WithNewInput(input string) tool.Option {
    return tool.WrapImplSpecificOptFn(func(t *askForClarificationOptions) {
       t.NewInput = &input
    })
}

import (
    "context"
    "log"

    "github.com/cloudwego/eino/components/tool"
    "github.com/cloudwego/eino/components/tool/utils"
    "github.com/cloudwego/eino/compose"
)

type askForClarificationOptions struct {
    NewInput *string
}

func WithNewInput(input string) tool.Option {
    return tool.WrapImplSpecificOptFn(func(t *askForClarificationOptions) {
       t.NewInput = &input
    })
}

type AskForClarificationInput struct {
    Question string `json:"question" jsonschema:"description=The specific question you want to ask the user to get the missing information"`
}

func NewAskForClarificationTool() tool.InvokableTool {
    t, err := utils.InferOptionableTool(
       "ask_for_clarification",
       "Call this tool when the user's request is ambiguous or lacks the necessary information to proceed. Use it to ask a follow-up question to get the details you need, such as the book's genre, before you can use other tools effectively.",
       func(ctx context.Context, input *AskForClarificationInput, opts ...tool.Option) (output string, err error) {
          o := tool.GetImplSpecificOptions[askForClarificationOptions](nil, opts...)
          if o.NewInput == nil {
             return "", compose.NewInterruptAndRerunErr(input.Question)
          }
          return *o.NewInput, nil
       })
    if err != nil {
       log.Fatal(err)
    }
    return t
}

func NewBookRecommendAgent() adk.Agent {
    // xxx
    a, err := adk.NewChatModelAgent(ctx, &adk.ChatModelAgentConfig{
       // xxx
       ToolsConfig: adk.ToolsConfig{
          ToolsNodeConfig: compose.ToolsNodeConfig{
             Tools: []tool.BaseTool{NewBookRecommender(), NewAskForClarificationTool()},
          },
          // Whether to output AgentEvents when calling SubAgent via AgentTool() internally
          EmitInternalEvents: true,
       },
    })
    // xxx
}

func newInMemoryStore() compose.CheckPointStore {
    return &inMemoryStore{
       mem: map[string][]byte{},
    }
}

func main() {
    ctx := context.Background()
    a := subagents.NewBookRecommendAgent()
    runner := adk.NewRunner(ctx, adk.RunnerConfig{
       EnableStreaming: true, // you can disable streaming here
       Agent:           a,
       CheckPointStore: newInMemoryStore(),
    })
    iter := runner.Query(ctx, "recommend a book to me", adk.WithCheckPointID("1"))
    for {
       event, ok := iter.Next()
       if !ok {
          break
       }
       if event.Err != nil {
          log.Fatal(event.Err)
       }
       if event.Action != nil && event.Action.Interrupted != nil {
          fmt.Printf("\ninterrupt happened, info: %+v\n", event.Action.Interrupted.Data.(*adk.ChatModelAgentInterruptInfo).RerunNodesExtra["ToolNode"])
          continue
       }
       msg, err := event.Output.MessageOutput.GetMessage()
       if err != nil {
          log.Fatal(err)
       }
       fmt.Printf("\nmessage:\n%v\n======\n\n", msg)
    }

    scanner := bufio.NewScanner(os.Stdin)
    fmt.Print("\nyour input here: ")
    scanner.Scan()
    fmt.Println()
    nInput := scanner.Text()

    iter, err := runner.Resume(ctx, "1", adk.WithToolOptions([]tool.Option{subagents.WithNewInput(nInput)}))
    if err != nil {
       log.Fatal(err)
    }
    for {
       event, ok := iter.Next()
       if !ok {
          break
       }

       if event.Err != nil {
          log.Fatal(event.Err)
       }

       prints.Event(event)
    }
}