// src/main/services/ChainService.ts
// Phase 10.4: Multi-LLM Chain 서비스.
// LLMChain을 electron-store에 저장하고, 체인을 순차 실행한다.

import { getLogger } from './LoggerService'
import { configGet } from './ConfigService'
import { getCustomInstructionService } from './CustomInstructionService'
import { getLocalLLMService } from './LocalLLMService'
import { getMainWindow } from '../windows/WindowManager'
import { IPC_CHANNELS } from '@d3ro/core/ipc-channels'
import { D3ROError, ErrorCode } from '@d3ro/core/errors'
import type {
  LLMChain,
  ChainStep,
  CreateChainParams,
  UpdateChainParams,
  ChainProgress,
  ChainExecutionResult
} from '@d3ro/core/types'

const logger = getLogger('chain-service')

// ============================================================
// 저장소 (electron-store, CustomInstructionService 패턴)
// ============================================================

let chains: LLMChain[] = []
let initialized = false

function loadChains(): LLMChain[] {
  try {
    const stored = configGet('llmChains' as never) as LLMChain[] | undefined
    if (Array.isArray(stored) && stored.length > 0) {
      return stored
    }
  } catch {
    // 첫 실행 시 키가 없을 수 있음
  }
  return []
}

function saveChains(): void {
  try {
    // eslint-disable-next-line @typescript-eslint/no-require-imports
    const { configSet } = require('./ConfigService') as {
      configSet: (key: never, value: never) => void
    }
    configSet('llmChains' as never, chains as never)
  } catch (error) {
    logger.warn(
      `Failed to save chains: ${error instanceof Error ? error.message : String(error)}`
    )
  }
}

/** 메인 윈도우 렌더러에 IPC 이벤트 전송 */
function sendProgressToRenderer(progress: ChainProgress): void {
  const win = getMainWindow()
  if (win && !win.isDestroyed()) {
    win.webContents.send(IPC_CHANNELS.CHAIN.PROGRESS, progress)
  }
}

// ============================================================
// ChainService
// ============================================================

class ChainService {
  private _cancelRequested = false

  initialize(): void {
    if (initialized) return
    chains = loadChains()
    initialized = true
    logger.info(`ChainService initialized (${chains.length} chains)`)
  }

  getAll(): LLMChain[] {
    return [...chains]
  }

  getById(id: string): LLMChain | null {
    return chains.find((c) => c.id === id) ?? null
  }

  create(params: CreateChainParams): LLMChain {
    const now = Date.now()
    const chain: LLMChain = {
      id: crypto.randomUUID(),
      name: params.name,
      steps: params.steps,
      createdAt: now,
      updatedAt: now
    }

    chains.push(chain)
    saveChains()
    logger.info(`Chain created: "${chain.name}" (${chain.steps.length} steps)`)
    return chain
  }

  update(params: UpdateChainParams): LLMChain {
    const index = chains.findIndex((c) => c.id === params.id)
    if (index === -1) {
      throw new D3ROError(ErrorCode.ChainNotFound, `Chain not found: ${params.id}`)
    }

    const existing = chains[index]
    const updated: LLMChain = {
      ...existing,
      name: params.name ?? existing.name,
      steps: params.steps ?? existing.steps,
      updatedAt: Date.now()
    }

    chains[index] = updated
    saveChains()
    logger.info(`Chain updated: "${updated.name}"`)
    return updated
  }

  delete(id: string): void {
    const index = chains.findIndex((c) => c.id === id)
    if (index === -1) {
      throw new D3ROError(ErrorCode.ChainNotFound, `Chain not found: ${id}`)
    }

    const removed = chains.splice(index, 1)[0]
    saveChains()
    logger.info(`Chain deleted: "${removed.name}"`)
  }

  /**
   * 체인을 순차 실행한다.
   * 각 단계마다 CustomInstruction의 프롬프트로 LLM을 호출하고,
   * 이전 단계 결과를 다음 단계의 입력으로 전달한다.
   */
  async execute(chainId: string, inputText: string): Promise<ChainExecutionResult> {
    const chain = this.getById(chainId)
    if (!chain) {
      throw new D3ROError(ErrorCode.ChainNotFound, `Chain not found: ${chainId}`)
    }

    if (chain.steps.length === 0) {
      throw new D3ROError(ErrorCode.ChainExecutionFailed, 'Chain has no steps')
    }

    this._cancelRequested = false
    const startTime = Date.now()
    const stepResults: Array<{ instructionId: string; output: string; durationMs: number }> = []
    let previousOutput = inputText

    const llm = getLocalLLMService()
    const instructionService = getCustomInstructionService()

    logger.info(
      `Executing chain "${chain.name}" (${chain.steps.length} steps) with input length ${inputText.length}`
    )

    for (let i = 0; i < chain.steps.length; i++) {
      // 취소 확인
      if (this._cancelRequested) {
        logger.info(`Chain execution cancelled at step ${i + 1}/${chain.steps.length}`)
        throw new D3ROError(ErrorCode.ChainCancelled, 'Chain execution cancelled')
      }

      const step: ChainStep = chain.steps[i]
      const instruction = instructionService.getById(step.instructionId)

      if (!instruction) {
        throw new D3ROError(
          ErrorCode.ChainStepFailed,
          `Instruction not found for step ${i + 1}: ${step.instructionId}`
        )
      }

      // 입력 소스 결정
      const stepInput = step.inputSource === 'original' ? inputText : previousOutput

      // 진행 상황 전송
      const progress: ChainProgress = {
        chainId,
        currentStep: i + 1,
        totalSteps: chain.steps.length,
        stepName: instruction.name,
        intermediateText: previousOutput
      }
      sendProgressToRenderer(progress)

      // LLM 호출
      const stepStart = Date.now()
      try {
        const result = await llm.processText(stepInput, 'custom', undefined, instruction.prompt)
        const stepDuration = Date.now() - stepStart

        stepResults.push({
          instructionId: step.instructionId,
          output: result,
          durationMs: stepDuration
        })
        previousOutput = result

        logger.info(
          `Chain step ${i + 1}/${chain.steps.length} ("${instruction.name}") completed in ${stepDuration}ms`
        )
      } catch (error) {
        if (error instanceof D3ROError && error.code === ErrorCode.ChainCancelled) {
          throw error
        }
        const msg =
          error instanceof Error ? error.message : String(error)
        throw new D3ROError(
          ErrorCode.ChainStepFailed,
          `Step ${i + 1} ("${instruction.name}") failed: ${msg}`
        )
      }
    }

    const totalDuration = Date.now() - startTime
    logger.info(`Chain "${chain.name}" completed in ${totalDuration}ms`)

    return {
      chainId,
      finalText: previousOutput,
      steps: stepResults,
      totalDurationMs: totalDuration
    }
  }

  /**
   * 진행 중인 체인 실행을 취소한다.
   * 현재 단계가 완료된 후 다음 단계 시작 전에 중단된다.
   */
  cancelExecution(): void {
    this._cancelRequested = true
    // LLM 생성도 취소
    getLocalLLMService().cancelGeneration()
    logger.info('Chain execution cancel requested')
  }

  dispose(): void {
    this._cancelRequested = true
    logger.info('ChainService disposed')
  }
}

// ============================================================
// 싱글톤
// ============================================================

let instance: ChainService | null = null

export function getChainService(): ChainService {
  if (!instance) {
    instance = new ChainService()
  }
  return instance
}