import { flatten } from 'lodash'
import { Tool } from '@langchain/core/tools'
import { BaseChatModel } from '@langchain/core/language_models/chat_models'
import { AIMessage, BaseMessage, HumanMessage } from '@langchain/core/messages'
import { ChainValues } from '@langchain/core/utils/types'
import { AgentStep } from '@langchain/core/agents'
import { renderTemplate, MessagesPlaceholder, HumanMessagePromptTemplate, PromptTemplate } from '@langchain/core/prompts'
import { RunnableSequence } from '@langchain/core/runnables'
import { ChatConversationalAgent } from 'langchain/agents'
import { getBaseClasses, transformBracesWithColon } from '../../../src/utils'
import { ConsoleCallbackHandler, CustomChainHandler, additionalCallbacks } from '../../../src/handler'
import {
    IVisionChatModal,
    FlowiseMemory,
    ICommonObject,
    INode,
    INodeData,
    INodeParams,
    IUsedTool,
    IServerSideEventStreamer
} from '../../../src/Interface'
import { AgentExecutor } from '../../../src/agents'
import { addImagesToMessages, llmSupportsVision } from '../../../src/multiModalUtils'
import { checkInputs, Moderation, streamResponse } from '../../moderation/Moderation'
import { formatResponse } from '../../outputparsers/OutputParserHelpers'

const DEFAULT_PREFIX = `Assistant is a large language model trained by OpenAI.

Assistant is designed to be able to assist with a wide range of tasks, from answering simple questions to providing in-depth explanations and discussions on a wide range of topics. As a language model, Assistant is able to generate human-like text based on the input it receives, allowing it to engage in natural-sounding conversations and provide responses that are coherent and relevant to the topic at hand.

Assistant is constantly learning and improving, and its capabilities are constantly evolving. It is able to process and understand large amounts of text, and can use this knowledge to provide accurate and informative responses to a wide range of questions. Additionally, Assistant is able to generate its own text based on the input it receives, allowing it to engage in discussions and provide explanations and descriptions on a wide range of topics.

Overall, Assistant is a powerful system that can help with a wide range of tasks and provide valuable insights and information on a wide range of topics. Whether you need help with a specific question or just want to have a conversation about a particular topic, Assistant is here to assist.`

const TEMPLATE_TOOL_RESPONSE = `TOOL RESPONSE:
---------------------
{observation}

USER'S INPUT
--------------------

Okay, so what is the response to my last comment? If using information obtained from the tools you must mention it explicitly without mentioning the tool names - I have forgotten all TOOL RESPONSES! Remember to respond with a markdown code snippet of a json blob with a single action, and NOTHING else.`

class ConversationalAgent_Agents implements INode {
    label: string
    name: string
    version: number
    description: string
    type: string
    icon: string
    category: string
    baseClasses: string[]
    inputs: INodeParams[]
    sessionId?: string

    constructor(fields?: { sessionId?: string }) {
        this.label = 'Conversational Agent'
        this.name = 'conversationalAgent'
        this.version = 3.0
        this.type = 'AgentExecutor'
        this.category = 'Agents'
        this.icon = 'agent.svg'
        this.description = 'Conversational agent for a chat model. It will utilize chat specific prompts'
        this.baseClasses = [this.type, ...getBaseClasses(AgentExecutor)]
        this.inputs = [
            {
                label: 'Allowed Tools',
                name: 'tools',
                type: 'Tool',
                list: true
            },
            {
                label: 'Chat Model',
                name: 'model',
                type: 'BaseChatModel'
            },
            {
                label: 'Memory',
                name: 'memory',
                type: 'BaseChatMemory'
            },
            {
                label: 'System Message',
                name: 'systemMessage',
                type: 'string',
                rows: 4,
                default: DEFAULT_PREFIX,
                optional: true,
                additionalParams: true
            },
            {
                label: 'Input Moderation',
                description: 'Detect text that could generate harmful output and prevent it from being sent to the language model',
                name: 'inputModeration',
                type: 'Moderation',
                optional: true,
                list: true
            },
            {
                label: 'Max Iterations',
                name: 'maxIterations',
                type: 'number',
                optional: true,
                additionalParams: true
            }
        ]
        this.sessionId = fields?.sessionId
    }

    async init(nodeData: INodeData, input: string, options: ICommonObject): Promise<any> {
        return prepareAgent(nodeData, options, { sessionId: this.sessionId, chatId: options.chatId, input })
    }

    async run(nodeData: INodeData, input: string, options: ICommonObject): Promise<string | object> {
        const memory = nodeData.inputs?.memory as FlowiseMemory
        const moderations = nodeData.inputs?.inputModeration as Moderation[]

        const shouldStreamResponse = options.shouldStreamResponse
        const sseStreamer: IServerSideEventStreamer = options.sseStreamer as IServerSideEventStreamer
        const chatId = options.chatId
        if (moderations && moderations.length > 0) {
            try {
                // Use the output of the moderation chain as input for the BabyAGI agent
                input = await checkInputs(moderations, input)
            } catch (e) {
                await new Promise((resolve) => setTimeout(resolve, 500))
                if (options.shouldStreamResponse) {
                    streamResponse(sseStreamer, chatId, e.message)
                }
                return formatResponse(e.message)
            }
        }
        const executor = await prepareAgent(nodeData, options, { sessionId: this.sessionId, chatId: options.chatId, input })

        const loggerHandler = new ConsoleCallbackHandler(options.logger, options?.orgId)
        const callbacks = await additionalCallbacks(nodeData, options)

        let res: ChainValues = {}
        let sourceDocuments: ICommonObject[] = []
        let usedTools: IUsedTool[] = []

        if (options.shouldStreamResponse) {
            const handler = new CustomChainHandler(shouldStreamResponse ? sseStreamer : undefined, chatId)
            res = await executor.invoke({ input }, { callbacks: [loggerHandler, handler, ...callbacks] })
            if (res.sourceDocuments) {
                if (options.sseStreamer) {
                    sseStreamer.streamSourceDocumentsEvent(options.chatId, flatten(res.sourceDocuments))
                }
                sourceDocuments = res.sourceDocuments
            }
            if (res.usedTools) {
                sseStreamer.streamUsedToolsEvent(options.chatId, res.usedTools)
                usedTools = res.usedTools
            }
            // If the tool is set to returnDirect, stream the output to the client
            if (res.usedTools && res.usedTools.length) {
                let inputTools = nodeData.inputs?.tools
                inputTools = flatten(inputTools)
                for (const tool of res.usedTools) {
                    const inputTool = inputTools.find((inputTool: Tool) => inputTool.name === tool.tool)
                    if (inputTool && inputTool.returnDirect && options.sseStreamer) {
                        sseStreamer.streamTokenEvent(options.chatId, tool.toolOutput)
                    }
                }
            }
            if (sseStreamer) {
                sseStreamer.streamEndEvent(options.chatId)
            }
        } else {
            res = await executor.invoke({ input }, { callbacks: [loggerHandler, ...callbacks] })
            if (res.sourceDocuments) {
                sourceDocuments = res.sourceDocuments
            }
            if (res.usedTools) {
                usedTools = res.usedTools
            }
        }

        await memory.addChatMessages(
            [
                {
                    text: input,
                    type: 'userMessage'
                },
                {
                    text: res?.output,
                    type: 'apiMessage'
                }
            ],
            this.sessionId
        )

        let finalRes = res?.output

        if (sourceDocuments.length || usedTools.length) {
            finalRes = { text: res?.output }
            if (sourceDocuments.length) {
                finalRes.sourceDocuments = flatten(sourceDocuments)
            }
            if (usedTools.length) {
                finalRes.usedTools = usedTools
            }
            return finalRes
        }

        return finalRes
    }
}

const prepareAgent = async (
    nodeData: INodeData,
    options: ICommonObject,
    flowObj: { sessionId?: string; chatId?: string; input?: string }
) => {
    const model = nodeData.inputs?.model as BaseChatModel
    const maxIterations = nodeData.inputs?.maxIterations as string
    let tools = nodeData.inputs?.tools as Tool[]
    tools = flatten(tools)
    const memory = nodeData.inputs?.memory as FlowiseMemory
    let systemMessage = nodeData.inputs?.systemMessage as string
    const memoryKey = memory.memoryKey ? memory.memoryKey : 'chat_history'
    const inputKey = memory.inputKey ? memory.inputKey : 'input'
    const prependMessages = options?.prependMessages

    const outputParser = ChatConversationalAgent.getDefaultOutputParser({
        llm: model,
        toolNames: tools.map((tool) => tool.name)
    })

    systemMessage = transformBracesWithColon(systemMessage)

    const prompt = ChatConversationalAgent.createPrompt(tools, {
        systemMessage: systemMessage ? systemMessage : DEFAULT_PREFIX,
        outputParser
    })

    if (llmSupportsVision(model)) {
        const visionChatModel = model as IVisionChatModal
        const messageContent = await addImagesToMessages(nodeData, options, model.multiModalOption)

        if (messageContent?.length) {
            visionChatModel.setVisionModel()

            // Pop the `agent_scratchpad` MessagePlaceHolder
            let messagePlaceholder = prompt.promptMessages.pop() as MessagesPlaceholder
            if (prompt.promptMessages.at(-1) instanceof HumanMessagePromptTemplate) {
                const lastMessage = prompt.promptMessages.pop() as HumanMessagePromptTemplate
                const template = (lastMessage.prompt as PromptTemplate).template as string
                const msg = HumanMessagePromptTemplate.fromTemplate([
                    ...messageContent,
                    {
                        text: template
                    }
                ])
                msg.inputVariables = lastMessage.inputVariables
                prompt.promptMessages.push(msg)
            }

            // Add the `agent_scratchpad` MessagePlaceHolder back
            prompt.promptMessages.push(messagePlaceholder)
        } else {
            visionChatModel.revertToOriginalModel()
        }
    }

    /** Bind a stop token to the model */
    const modelWithStop = model.bind({
        stop: ['\nObservation']
    })

    const runnableAgent = RunnableSequence.from([
        {
            [inputKey]: (i: { input: string; steps: AgentStep[] }) => i.input,
            agent_scratchpad: async (i: { input: string; steps: AgentStep[] }) => await constructScratchPad(i.steps),
            [memoryKey]: async (_: { input: string; steps: AgentStep[] }) => {
                const messages = (await memory.getChatMessages(flowObj?.sessionId, true, prependMessages)) as BaseMessage[]
                return messages ?? []
            }
        },
        prompt,
        modelWithStop,
        outputParser
    ])

    const executor = AgentExecutor.fromAgentAndTools({
        agent: runnableAgent,
        tools,
        sessionId: flowObj?.sessionId,
        chatId: flowObj?.chatId,
        input: flowObj?.input,
        verbose: process.env.DEBUG === 'true',
        maxIterations: maxIterations ? parseFloat(maxIterations) : undefined
    })

    return executor
}

const constructScratchPad = async (steps: AgentStep[]): Promise<BaseMessage[]> => {
    const thoughts: BaseMessage[] = []
    for (const step of steps) {
        thoughts.push(new AIMessage(step.action.log))
        thoughts.push(
            new HumanMessage(
                renderTemplate(TEMPLATE_TOOL_RESPONSE, 'f-string', {
                    observation: step.observation
                })
            )
        )
    }
    return thoughts
}

module.exports = { nodeClass: ConversationalAgent_Agents }