import axios from 'axios'
import { constants as fsConstants } from 'fs'
import { access, writeFile } from 'fs/promises'
import { homedir } from 'os'
import { join } from 'path'
import { getDynamicConfig_BLOCKS_ON_INIT } from 'src/services/analytics/growthbook.js'
import {
  type AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS,
  logEvent,
} from 'src/services/analytics/index.js'
import { type ReleaseChannel, saveGlobalConfig } from './config.js'
import { logForDebugging } from './debug.js'
import { env } from './env.js'
import { getClaudeConfigHomeDir } from './envUtils.js'
import { ClaudeError, getErrnoCode, isENOENT } from './errors.js'
import { execFileNoThrowWithCwd } from './execFileNoThrow.js'
import { getFsImplementation } from './fsOperations.js'
import { gracefulShutdownSync } from './gracefulShutdown.js'
import { logError } from './log.js'
import { gte, lt } from './semver.js'
import { getInitialSettings } from './settings/settings.js'
import {
  filterClaudeAliases,
  getShellConfigPaths,
  readFileLines,
  writeFileLines,
} from './shellConfig.js'
import { jsonParse } from './slowOperations.js'

const GCS_BUCKET_URL =
  'https://storage.googleapis.com/claude-code-dist-86c565f3-f756-42ad-8dfa-d59b1c096819/claude-code-releases'

class AutoUpdaterError extends ClaudeError {}

export type InstallStatus =
  | 'success'
  | 'no_permissions'
  | 'install_failed'
  | 'in_progress'

export type AutoUpdaterResult = {
  version: string | null
  status: InstallStatus
  notifications?: string[]
}

export type MaxVersionConfig = {
  external?: string
  ant?: string
  external_message?: string
  ant_message?: string
}

/**
 * Checks if the current version meets the minimum required version from Statsig config
 * Terminates the process with an error message if the version is too old
 *
 * NOTE ON SHA-BASED VERSIONING:
 * We use SemVer-compliant versioning with build metadata format (X.X.X+SHA) for continuous deployment.
 * According to SemVer specs, build metadata (the +SHA part) is ignored when comparing versions.
 *
 * Versioning approach:
 * 1. For version requirements/compatibility (assertMinVersion), we use semver comparison that ignores build metadata
 * 2. For updates ('claude update'), we use exact string comparison to detect any change, including SHA
 *    - This ensures users always get the latest build, even when only the SHA changes
 *    - The UI clearly shows both versions including build metadata
 *
 * This approach keeps version comparison logic simple while maintaining traceability via the SHA.
 */
export async function assertMinVersion(): Promise<void> {
  return
}

/**
 * Returns the maximum allowed version for the current user type.
 * For ants, returns the `ant` field (dev version format).
 * For external users, returns the `external` field (clean semver).
 * This is used as a server-side kill switch to pause auto-updates during incidents.
 * Returns undefined if no cap is configured.
 */
export async function getMaxVersion(): Promise<string | undefined> {
  return undefined
}

/**
 * Returns the server-driven message explaining the known issue, if configured.
 * Shown in the warning banner when the current version exceeds the max allowed version.
 */
export async function getMaxVersionMessage(): Promise<string | undefined> {
  return undefined
}

async function getMaxVersionConfig(): Promise<MaxVersionConfig> {
  try {
    return await getDynamicConfig_BLOCKS_ON_INIT<MaxVersionConfig>(
      'tengu_max_version_config',
      {},
    )
  } catch (error) {
    logError(error as Error)
    return {}
  }
}

/**
 * Checks if a target version should be skipped due to user's minimumVersion setting.
 * This is used when switching to stable channel - the user can choose to stay on their
 * current version until stable catches up, preventing downgrades.
 */
export function shouldSkipVersion(targetVersion: string): boolean {
  const settings = getInitialSettings()
  const minimumVersion = settings?.minimumVersion
  if (!minimumVersion) {
    return false
  }
  // Skip if target version is less than minimum
  const shouldSkip = !gte(targetVersion, minimumVersion)
  if (shouldSkip) {
    logForDebugging(
      `Skipping update to ${targetVersion} - below minimumVersion ${minimumVersion}`,
    )
  }
  return shouldSkip
}

// Lock file for auto-updater to prevent concurrent updates
const LOCK_TIMEOUT_MS = 5 * 60 * 1000 // 5 minute timeout for locks

/**
 * Get the path to the lock file
 * This is a function to ensure it's evaluated at runtime after test setup
 */
export function getLockFilePath(): string {
  return join(getClaudeConfigHomeDir(), '.update.lock')
}

/**
 * Attempts to acquire a lock for auto-updater
 * @returns true if lock was acquired, false if another process holds the lock
 */
async function acquireLock(): Promise<boolean> {
  const fs = getFsImplementation()
  const lockPath = getLockFilePath()

  // Check for existing lock: 1 stat() on the happy path (fresh lock or ENOENT),
  // 2 on stale-lock recovery (re-verify staleness immediately before unlink).
  try {
    const stats = await fs.stat(lockPath)
    const age = Date.now() - stats.mtimeMs
    if (age < LOCK_TIMEOUT_MS) {
      return false
    }
    // Lock is stale, remove it before taking over. Re-verify staleness
    // immediately before unlinking to close a TOCTOU race: if two processes
    // both observe the stale lock, A unlinks + writes a fresh lock, then B
    // would unlink A's fresh lock and both believe they hold it. A fresh
    // lock has a recent mtime, so re-checking staleness makes B back off.
    try {
      const recheck = await fs.stat(lockPath)
      if (Date.now() - recheck.mtimeMs < LOCK_TIMEOUT_MS) {
        return false
      }
      await fs.unlink(lockPath)
    } catch (err) {
      if (!isENOENT(err)) {
        logError(err as Error)
        return false
      }
    }
  } catch (err) {
    if (!isENOENT(err)) {
      logError(err as Error)
      return false
    }
    // ENOENT: no lock file, proceed to create one
  }

  // Create lock file atomically with O_EXCL (flag: 'wx'). If another process
  // wins the race and creates it first, we get EEXIST and back off.
  // Lazy-mkdir the config dir on ENOENT.
  try {
    await writeFile(lockPath, `${process.pid}`, {
      encoding: 'utf8',
      flag: 'wx',
    })
    return true
  } catch (err) {
    const code = getErrnoCode(err)
    if (code === 'EEXIST') {
      return false
    }
    if (code === 'ENOENT') {
      try {
        // fs.mkdir from getFsImplementation() is always recursive:true and
        // swallows EEXIST internally, so a dir-creation race cannot reach the
        // catch below — only writeFile's EEXIST (true lock contention) can.
        await fs.mkdir(getClaudeConfigHomeDir())
        await writeFile(lockPath, `${process.pid}`, {
          encoding: 'utf8',
          flag: 'wx',
        })
        return true
      } catch (mkdirErr) {
        if (getErrnoCode(mkdirErr) === 'EEXIST') {
          return false
        }
        logError(mkdirErr as Error)
        return false
      }
    }
    logError(err as Error)
    return false
  }
}

/**
 * Releases the update lock if it's held by this process
 */
async function releaseLock(): Promise<void> {
  const fs = getFsImplementation()
  const lockPath = getLockFilePath()
  try {
    const lockData = await fs.readFile(lockPath, { encoding: 'utf8' })
    if (lockData === `${process.pid}`) {
      await fs.unlink(lockPath)
    }
  } catch (err) {
    if (isENOENT(err)) {
      return
    }
    logError(err as Error)
  }
}

async function getInstallationPrefix(): Promise<string | null> {
  // Run from home directory to avoid reading project-level .npmrc/.bunfig.toml
  const isBun = env.isRunningWithBun()
  let prefixResult = null
  if (isBun) {
    prefixResult = await execFileNoThrowWithCwd('bun', ['pm', 'bin', '-g'], {
      cwd: homedir(),
    })
  } else {
    prefixResult = await execFileNoThrowWithCwd(
      'npm',
      ['-g', 'config', 'get', 'prefix'],
      { cwd: homedir() },
    )
  }
  if (prefixResult.code !== 0) {
    logError(new Error(`Failed to check ${isBun ? 'bun' : 'npm'} permissions`))
    return null
  }
  return prefixResult.stdout.trim()
}

export async function checkGlobalInstallPermissions(): Promise<{
  hasPermissions: boolean
  npmPrefix: string | null
}> {
  try {
    const prefix = await getInstallationPrefix()
    if (!prefix) {
      return { hasPermissions: false, npmPrefix: null }
    }

    try {
      await access(prefix, fsConstants.W_OK)
      return { hasPermissions: true, npmPrefix: prefix }
    } catch {
      logError(
        new AutoUpdaterError(
          'Insufficient permissions for global npm install.',
        ),
      )
      return { hasPermissions: false, npmPrefix: prefix }
    }
  } catch (error) {
    logError(error as Error)
    return { hasPermissions: false, npmPrefix: null }
  }
}

export async function getLatestVersion(
  channel: ReleaseChannel,
): Promise<string | null> {
  void channel
  return MACRO.VERSION
}

export type NpmDistTags = {
  latest: string | null
  stable: string | null
}

/**
 * Get npm dist-tags (latest and stable versions) from the registry.
 * This is used by the doctor command to show users what versions are available.
 */
export async function getNpmDistTags(): Promise<NpmDistTags> {
  // Run from home directory to avoid reading project-level .npmrc
  const result = await execFileNoThrowWithCwd(
    'npm',
    ['view', MACRO.PACKAGE_URL, 'dist-tags', '--json', '--prefer-online'],
    { abortSignal: AbortSignal.timeout(5000), cwd: homedir() },
  )

  if (result.code !== 0) {
    logForDebugging(`npm view dist-tags failed with code ${result.code}`)
    return { latest: null, stable: null }
  }

  try {
    const parsed = jsonParse(result.stdout.trim()) as Record<string, unknown>
    return {
      latest: typeof parsed.latest === 'string' ? parsed.latest : null,
      stable: typeof parsed.stable === 'string' ? parsed.stable : null,
    }
  } catch (error) {
    logForDebugging(`Failed to parse dist-tags: ${error}`)
    return { latest: null, stable: null }
  }
}

/**
 * Get the latest version from GCS bucket for a given release channel.
 * This is used by installations that don't have npm (e.g. package manager installs).
 */
export async function getLatestVersionFromGcs(
  channel: ReleaseChannel,
): Promise<string | null> {
  void channel
  return MACRO.VERSION
}

/**
 * Get available versions from GCS bucket (for native installations).
 * Fetches both latest and stable channel pointers.
 */
export async function getGcsDistTags(): Promise<NpmDistTags> {
  const [latest, stable] = await Promise.all([
    getLatestVersionFromGcs('latest'),
    getLatestVersionFromGcs('stable'),
  ])

  return { latest, stable }
}

/**
 * Get version history from npm registry (ant-only feature)
 * Returns versions sorted newest-first, limited to the specified count
 *
 * Uses NATIVE_PACKAGE_URL when available because:
 * 1. Native installation is the primary installation method for ant users
 * 2. Not all JS package versions have corresponding native packages
 * 3. This prevents rollback from listing versions that don't have native binaries
 */
export async function getVersionHistory(limit: number): Promise<string[]> {
  if (process.env.USER_TYPE !== 'ant') {
    return []
  }

  // Use native package URL when available to ensure we only show versions
  // that have native binaries (not all JS package versions have native builds)
  const packageUrl = MACRO.NATIVE_PACKAGE_URL ?? MACRO.PACKAGE_URL

  // Run from home directory to avoid reading project-level .npmrc
  const result = await execFileNoThrowWithCwd(
    'npm',
    ['view', packageUrl, 'versions', '--json', '--prefer-online'],
    // Longer timeout for version list
    { abortSignal: AbortSignal.timeout(30000), cwd: homedir() },
  )

  if (result.code !== 0) {
    logForDebugging(`npm view versions failed with code ${result.code}`)
    if (result.stderr) {
      logForDebugging(`npm stderr: ${result.stderr.trim()}`)
    }
    return []
  }

  try {
    const versions = jsonParse(result.stdout.trim()) as string[]
    // Take last N versions, then reverse to get newest first
    return versions.slice(-limit).reverse()
  } catch (error) {
    logForDebugging(`Failed to parse version history: ${error}`)
    return []
  }
}

export async function installGlobalPackage(
  specificVersion?: string | null,
): Promise<InstallStatus> {
  void specificVersion
  return 'install_failed'
}

/**
 * Remove claude aliases from shell configuration files
 * This helps clean up old installation methods when switching to native or npm global
 */
async function removeClaudeAliasesFromShellConfigs(): Promise<void> {
  const configMap = getShellConfigPaths()

  // Process each shell config file
  for (const [, configFile] of Object.entries(configMap)) {
    try {
      const lines = await readFileLines(configFile)
      if (!lines) continue

      const { filtered, hadAlias } = filterClaudeAliases(lines)

      if (hadAlias) {
        await writeFileLines(configFile, filtered)
        logForDebugging(`Removed claude alias from ${configFile}`)
      }
    } catch (error) {
      // Don't fail the whole operation if one file can't be processed
      logForDebugging(`Failed to remove alias from ${configFile}: ${error}`, {
        level: 'error',
      })
    }
  }
}