import { existsSync, mkdirSync, readFileSync, writeFileSync } from 'fs'
import { join } from 'path'
import { DEFAULT_SHORTCUTS } from '../../shared/default-shortcuts'
import { DEFAULT_AI_CONFIG, type GlobalSettings } from '../../shared/types'

const FILE = 'global_settings.json'

function defaultAiConfig() {
  return {
    ...DEFAULT_AI_CONFIG,
    baseUrl: process.env.BILIN_AI_BASE_URL ?? DEFAULT_AI_CONFIG.baseUrl,
    model: process.env.BILIN_AI_MODEL ?? DEFAULT_AI_CONFIG.model
  }
}

function defaults(): GlobalSettings {
  return {
    penName: '未命名作者',
    onboardingCompleted: false,
    theme: 'default',
    language: 'zh-CN',
    dailyWordGoal: 0,
    updateSchedule: 'none',
    stockBufferThreshold: 3,
    shortcuts: { ...DEFAULT_SHORTCUTS },
    snapshotIntervalMs: 300_000,
    snapshotMaxAuto: 20,
    snapshotMaxPersist: 3,
    searchHistory: [],
    aiConfig: defaultAiConfig(),
    namingIgnoreWords: [],
    knowledgeAutoSuggest: true,
    knowledgeSuggestTopN: 8
  }
}

export class GlobalSettingsService {
  constructor(private userDataDir: string) {
    if (!existsSync(userDataDir)) mkdirSync(userDataDir, { recursive: true })
  }

  private filePath(): string {
    return join(this.userDataDir, FILE)
  }

  get(): GlobalSettings {
    if (!existsSync(this.filePath())) return defaults()
    const raw = JSON.parse(readFileSync(this.filePath(), 'utf-8')) as Partial<GlobalSettings>
    return {
      ...defaults(),
      ...raw,
      updateSchedule: raw.updateSchedule ?? 'none',
      stockBufferThreshold: raw.stockBufferThreshold ?? 3,
      knowledgeAutoSuggest: raw.knowledgeAutoSuggest ?? true,
      knowledgeSuggestTopN: raw.knowledgeSuggestTopN ?? 8,
      shortcuts: { ...DEFAULT_SHORTCUTS, ...raw.shortcuts },
      aiConfig: { ...DEFAULT_AI_CONFIG, ...raw.aiConfig }
    }
  }

  update(partial: Partial<GlobalSettings>): GlobalSettings {
    const current = this.get()
    const next: GlobalSettings = {
      ...current,
      ...partial,
      shortcuts: partial.shortcuts
        ? { ...current.shortcuts, ...partial.shortcuts }
        : current.shortcuts,
      aiConfig: partial.aiConfig ? { ...current.aiConfig, ...partial.aiConfig } : current.aiConfig
    }
    writeFileSync(this.filePath(), JSON.stringify(next, null, 2), 'utf-8')
    return next
  }
}