/**
 * Provider Service — preset-based provider configuration
 *
 * Storage: ~/.claude/cc-haha/providers.json (lightweight index)
 * Active provider env vars written to ~/.claude/settings.json
 */

import * as fs from 'fs/promises'
import * as path from 'path'
import * as os from 'os'
import { ApiError } from '../middleware/errorHandler.js'
import type {
  SavedProvider,
  ProvidersIndex,
  CreateProviderInput,
  UpdateProviderInput,
  TestProviderInput,
  ProviderTestResult,
} from '../types/provider.js'

const MANAGED_ENV_KEYS = [
  'ANTHROPIC_BASE_URL',
  'ANTHROPIC_AUTH_TOKEN',
  'ANTHROPIC_MODEL',
  'ANTHROPIC_DEFAULT_HAIKU_MODEL',
  'ANTHROPIC_DEFAULT_SONNET_MODEL',
  'ANTHROPIC_DEFAULT_OPUS_MODEL',
] as const

const DEFAULT_INDEX: ProvidersIndex = { activeId: null, providers: [] }

export class ProviderService {
  private getConfigDir(): string {
    return process.env.CLAUDE_CONFIG_DIR || path.join(os.homedir(), '.claude')
  }

  private getCcHahaDir(): string {
    return path.join(this.getConfigDir(), 'cc-haha')
  }

  private getIndexPath(): string {
    return path.join(this.getCcHahaDir(), 'providers.json')
  }

  private getSettingsPath(): string {
    return path.join(this.getConfigDir(), 'settings.json')
  }

  private async readIndex(): Promise<ProvidersIndex> {
    try {
      const raw = await fs.readFile(this.getIndexPath(), 'utf-8')
      return JSON.parse(raw) as ProvidersIndex
    } catch (err: unknown) {
      if ((err as NodeJS.ErrnoException).code === 'ENOENT') {
        return { ...DEFAULT_INDEX, providers: [] }
      }
      throw ApiError.internal(`Failed to read providers index: ${err}`)
    }
  }

  private async writeIndex(index: ProvidersIndex): Promise<void> {
    const filePath = this.getIndexPath()
    const dir = path.dirname(filePath)
    await fs.mkdir(dir, { recursive: true })

    const tmpFile = `${filePath}.tmp.${Date.now()}`
    try {
      await fs.writeFile(tmpFile, JSON.stringify(index, null, 2) + '\n', 'utf-8')
      await fs.rename(tmpFile, filePath)
    } catch (err) {
      await fs.unlink(tmpFile).catch(() => {})
      throw ApiError.internal(`Failed to write providers index: ${err}`)
    }
  }

  private async readSettings(): Promise<Record<string, unknown>> {
    try {
      const raw = await fs.readFile(this.getSettingsPath(), 'utf-8')
      return JSON.parse(raw) as Record<string, unknown>
    } catch (err: unknown) {
      if ((err as NodeJS.ErrnoException).code === 'ENOENT') return {}
      throw ApiError.internal(`Failed to read settings.json: ${err}`)
    }
  }

  private async writeSettings(settings: Record<string, unknown>): Promise<void> {
    const filePath = this.getSettingsPath()
    const dir = path.dirname(filePath)
    await fs.mkdir(dir, { recursive: true })

    const tmpFile = `${filePath}.tmp.${Date.now()}`
    try {
      await fs.writeFile(tmpFile, JSON.stringify(settings, null, 2) + '\n', 'utf-8')
      await fs.rename(tmpFile, filePath)
    } catch (err) {
      await fs.unlink(tmpFile).catch(() => {})
      throw ApiError.internal(`Failed to write settings.json: ${err}`)
    }
  }

  // --- CRUD ---

  async listProviders(): Promise<{ providers: SavedProvider[]; activeId: string | null }> {
    const index = await this.readIndex()
    return { providers: index.providers, activeId: index.activeId }
  }

  async getProvider(id: string): Promise<SavedProvider> {
    const index = await this.readIndex()
    const provider = index.providers.find((p) => p.id === id)
    if (!provider) throw ApiError.notFound(`Provider not found: ${id}`)
    return provider
  }

  async addProvider(input: CreateProviderInput): Promise<SavedProvider> {
    const index = await this.readIndex()

    const provider: SavedProvider = {
      id: crypto.randomUUID(),
      presetId: input.presetId,
      name: input.name,
      apiKey: input.apiKey,
      baseUrl: input.baseUrl,
      models: input.models,
      ...(input.notes !== undefined && { notes: input.notes }),
    }

    index.providers.push(provider)
    await this.writeIndex(index)
    return provider
  }

  async updateProvider(id: string, input: UpdateProviderInput): Promise<SavedProvider> {
    const index = await this.readIndex()
    const idx = index.providers.findIndex((p) => p.id === id)
    if (idx === -1) throw ApiError.notFound(`Provider not found: ${id}`)

    const existing = index.providers[idx]
    const updated: SavedProvider = {
      ...existing,
      ...(input.name !== undefined && { name: input.name }),
      ...(input.apiKey !== undefined && { apiKey: input.apiKey }),
      ...(input.baseUrl !== undefined && { baseUrl: input.baseUrl }),
      ...(input.models !== undefined && { models: input.models }),
      ...(input.notes !== undefined && { notes: input.notes }),
    }

    index.providers[idx] = updated
    await this.writeIndex(index)

    if (index.activeId === id) {
      await this.syncToSettings(updated)
    }

    return updated
  }

  async deleteProvider(id: string): Promise<void> {
    const index = await this.readIndex()
    const idx = index.providers.findIndex((p) => p.id === id)
    if (idx === -1) throw ApiError.notFound(`Provider not found: ${id}`)

    if (index.activeId === id) {
      throw ApiError.conflict('Cannot delete the active provider. Switch to another provider first.')
    }

    index.providers.splice(idx, 1)
    await this.writeIndex(index)
  }

  // --- Activation ---

  async activateProvider(id: string): Promise<void> {
    const index = await this.readIndex()
    const provider = index.providers.find((p) => p.id === id)
    if (!provider) throw ApiError.notFound(`Provider not found: ${id}`)

    index.activeId = id
    await this.writeIndex(index)

    if (provider.presetId === 'official') {
      await this.clearProviderFromSettings()
    } else {
      await this.syncToSettings(provider)
    }
  }

  async activateOfficial(): Promise<void> {
    const index = await this.readIndex()
    index.activeId = null
    await this.writeIndex(index)
    await this.clearProviderFromSettings()
  }

  // --- Settings sync ---

  private async syncToSettings(provider: SavedProvider): Promise<void> {
    const settings = await this.readSettings()
    const existingEnv = (settings.env as Record<string, string>) || {}

    settings.env = {
      ...existingEnv,
      ANTHROPIC_BASE_URL: provider.baseUrl,
      ANTHROPIC_AUTH_TOKEN: provider.apiKey,
      ANTHROPIC_MODEL: provider.models.main,
      ANTHROPIC_DEFAULT_HAIKU_MODEL: provider.models.haiku,
      ANTHROPIC_DEFAULT_SONNET_MODEL: provider.models.sonnet,
      ANTHROPIC_DEFAULT_OPUS_MODEL: provider.models.opus,
    }

    await this.writeSettings(settings)
  }

  private async clearProviderFromSettings(): Promise<void> {
    const settings = await this.readSettings()
    const env = (settings.env as Record<string, string>) || {}

    for (const key of MANAGED_ENV_KEYS) {
      delete env[key]
    }

    settings.env = env
    if (Object.keys(env).length === 0) {
      delete settings.env
    }

    await this.writeSettings(settings)
  }

  // --- Test ---

  async testProvider(id: string): Promise<ProviderTestResult> {
    const provider = await this.getProvider(id)
    if (!provider.baseUrl || !provider.apiKey) {
      return { success: false, latencyMs: 0, error: 'Missing baseUrl or apiKey' }
    }
    return this.testProviderConfig({
      baseUrl: provider.baseUrl,
      apiKey: provider.apiKey,
      modelId: provider.models.main,
    })
  }

  async testProviderConfig(input: TestProviderInput): Promise<ProviderTestResult> {
    const url = `${input.baseUrl.replace(/\/+$/, '')}/v1/messages`
    const start = Date.now()

    try {
      const response = await fetch(url, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          'x-api-key': input.apiKey,
          'anthropic-version': '2023-06-01',
        },
        body: JSON.stringify({
          model: input.modelId,
          max_tokens: 1,
          messages: [{ role: 'user', content: 'Hi' }],
        }),
        signal: AbortSignal.timeout(15000),
      })

      const latencyMs = Date.now() - start

      if (response.ok) {
        return { success: true, latencyMs, modelUsed: input.modelId, httpStatus: response.status }
      }

      let errorMessage = `HTTP ${response.status}`
      try {
        const body = (await response.json()) as Record<string, unknown>
        if (body.error && typeof body.error === 'object') {
          errorMessage = ((body.error as Record<string, unknown>).message as string) || errorMessage
        } else if (typeof body.message === 'string') {
          errorMessage = body.message
        }
      } catch {
        errorMessage = `HTTP ${response.status} ${response.statusText}`
      }

      return { success: false, latencyMs, error: errorMessage, modelUsed: input.modelId, httpStatus: response.status }
    } catch (err: unknown) {
      const latencyMs = Date.now() - start
      if (err instanceof DOMException && err.name === 'TimeoutError') {
        return { success: false, latencyMs, error: 'Request timed out after 15 seconds', modelUsed: input.modelId }
      }
      return { success: false, latencyMs, error: err instanceof Error ? err.message : String(err), modelUsed: input.modelId }
    }
  }
}