import {
  getFullReadUrl,
  connectToGaiaHub, uploadToGaiaHub, getBucketUrl, BLOCKSTACK_GAIA_HUB_LABEL, 
  GaiaHubConfig,
  deleteFromGaiaHub
} from './hub'
// export { type GaiaHubConfig } from './hub'

import {
  encryptECIES, decryptECIES, signECDSA, verifyECDSA
} from '../encryption/ec'
import { getPublicKeyFromPrivate, publicKeyToAddress } from '../keys'
import { lookupProfile } from '../profiles/profileLookup'
import {
  InvalidStateError,
  SignatureVerificationError
} from '../errors'
import { Logger } from '../logger'

import { UserSession } from '../auth/userSession'
import { getGlobalObject } from '../utils'
import { fetchPrivate } from '../fetchUtil'

/**
 * Specify a valid MIME type, encryption, and whether to sign the [[UserSession.putFile]].
 */
export interface PutFileOptions {
  /**
  * Encrypt the data with the app public key. 
  * If a string is specified, it is used as the public key. 
  * If the boolean `true` is specified then the current user's app public key is used. 
   * @default true
   */
  encrypt?: boolean | string;
  /**
   * Sign the data using ECDSA on SHA256 hashes with the user's app private key. 
   * If a string is specified, it is used as the private key. 
   * @default false
   */
  sign?: boolean | string;
  /**
   * Set a Content-Type header for unencrypted data. 
   */
  contentType?: string;
}

const SIGNATURE_FILE_SUFFIX = '.sig'

/**
 * Fetch the public read URL of a user file for the specified app.
 * @param {String} path - the path to the file to read
 * @param {String} username - The Blockstack ID of the user to look up
 * @param {String} appOrigin - The app origin
 * @param {String} [zoneFileLookupURL=null] - The URL
 * to use for zonefile lookup. If falsey, this will use the
 * blockstack.js's [[getNameInfo]] function instead.
 * @return {Promise<string>} that resolves to the public read URL of the file
 * or rejects with an error
 */
export async function getUserAppFileUrl(
  path: string, username: string, appOrigin: string,
  zoneFileLookupURL?: string
): Promise<string|null> {
  const profile = await lookupProfile(username, zoneFileLookupURL)
  let bucketUrl: string = null
  if (profile.hasOwnProperty('apps')) {
    if (profile.apps.hasOwnProperty(appOrigin)) {
      const url = profile.apps[appOrigin]
      const bucket = url.replace(/\/?(\?|#|$)/, '/$1')
      bucketUrl = `${bucket}${path}`
    }
  }
  return bucketUrl
}

/**
 * 
 * 
 * @deprecated 
 * #### v19 Use [[UserSession.encryptContent]].
 *
 * Encrypts the data provided with the app public key.
 * @param {String|Buffer} content - data to encrypt
 * @param {Object} [options=null] - options object
 * @param {String} options.publicKey - the hex string of the ECDSA public
 * key to use for encryption. If not provided, will use user's appPublicKey.
 * @return {String} Stringified ciphertext object
 */
export function encryptContent(
  content: string | Buffer,
  options?: {
    publicKey?: string
  },
  caller?: UserSession
) {
  const opts = Object.assign({}, options)
  if (!opts.publicKey) {
    const privateKey = (caller || new UserSession()).loadUserData().appPrivateKey
    opts.publicKey = getPublicKeyFromPrivate(privateKey)
  }
  const cipherObject = encryptECIES(opts.publicKey, content)
  return JSON.stringify(cipherObject)
}

/**
 * 
 * @deprecated 
 * #### v19 Use [[UserSession.decryptContent]].
 * 
 * Decrypts data encrypted with `encryptContent` with the
 * transit private key.
 * @param {String|Buffer} content - encrypted content.
 * @param {Object} [options=null] - options object
 * @param {String} options.privateKey - the hex string of the ECDSA private
 * key to use for decryption. If not provided, will use user's appPrivateKey.
 * @return {String|Buffer} decrypted content.
 */
export function decryptContent(
  content: string,
  options?: {
    privateKey?: string
  },
  caller?: UserSession
) {
  const opts = Object.assign({}, options)
  if (!opts.privateKey) {
    opts.privateKey = (caller || new UserSession()).loadUserData().appPrivateKey
  }

  try {
    const cipherObject = JSON.parse(content)
    return decryptECIES(opts.privateKey, cipherObject)
  } catch (err) {
    if (err instanceof SyntaxError) {
      throw new Error('Failed to parse encrypted content JSON. The content may not '
                      + 'be encrypted. If using getFile, try passing { decrypt: false }.')
    } else {
      throw err
    }
  }
}

/* Get the gaia address used for servicing multiplayer reads for the given
 * (username, app) pair.
 * @private
 * @ignore
 */
async function getGaiaAddress(
  app: string, username?: string, zoneFileLookupURL?: string,
  caller?: UserSession
): Promise<string> {
  const opts = normalizeOptions({ app, username }, caller)
  let fileUrl: string
  if (username) {
    fileUrl = await getUserAppFileUrl('/', opts.username, opts.app, zoneFileLookupURL)
  } else {
    if (!caller) {
      caller = new UserSession()
    }
    const gaiaHubConfig = await caller.getOrSetLocalGaiaHubConnection()
    fileUrl = await getFullReadUrl('/', gaiaHubConfig)
  }
  const matches = fileUrl.match(/([13][a-km-zA-HJ-NP-Z0-9]{26,35})/)
  if (!matches) {
    throw new Error('Failed to parse gaia address')
  }
  return matches[matches.length - 1]
}
/**
 * @param {Object} [options=null] - options object
 * @param {String} options.username - the Blockstack ID to lookup for multi-player storage
 * @param {String} options.app - the app to lookup for multi-player storage -
 * defaults to current origin
 * 
 * @ignore
 */
function normalizeOptions<T>(
  options?: {
    app?: string, 
    username?: string
  } & T,
  caller?: UserSession
) {
  const opts = Object.assign({}, options)
  if (opts.username) {
    if (!opts.app) {
      const appConfig = (caller || new UserSession()).appConfig
      if (!appConfig) {
        throw new InvalidStateError('Missing AppConfig')
      }
      opts.app = appConfig.appDomain
    }
  }
  return opts
}

/**
 * @deprecated
 * #### v19 Use [[UserSession.getFileUrl]] instead.
 * 
 * @param {String} path - the path to the file to read
 * @returns {Promise<string>} that resolves to the URL or rejects with an error
 */
export async function getFileUrl(
  path: string, 
  options?: GetFileUrlOptions,
  caller?: UserSession
): Promise<string> {
  const opts = normalizeOptions(options, caller)

  let readUrl: string
  if (opts.username) {
    readUrl = await getUserAppFileUrl(path, opts.username, opts.app, opts.zoneFileLookupURL)
  } else {
    const gaiaHubConfig = await (caller || new UserSession()).getOrSetLocalGaiaHubConnection()
    readUrl = await getFullReadUrl(path, gaiaHubConfig)
  }

  if (!readUrl) {
    throw new Error('Missing readURL')
  } else {
    return readUrl
  }
}

/* Handle fetching the contents from a given path. Handles both
 *  multi-player reads and reads from own storage.
 * @private
 * @ignore
 */
function getFileContents(path: string, app: string, username: string | undefined, 
                         zoneFileLookupURL: string | undefined,
                         forceText: boolean,
                         caller?: UserSession): Promise<string | ArrayBuffer | null> {
  return Promise.resolve()
    .then(() => {
      const opts = { app, username, zoneFileLookupURL }
      return getFileUrl(path, opts, caller)
    })
    .then(readUrl => fetchPrivate(readUrl))
    .then<string | ArrayBuffer | null>((response) => {
      if (response.status !== 200) {
        if (response.status === 404) {
          Logger.debug(`getFile ${path} returned 404, returning null`)
          return null
        } else {
          throw new Error(`getFile ${path} failed with HTTP status ${response.status}`)
        }
      }
      const contentType = response.headers.get('Content-Type')
      if (forceText || contentType === null
          || contentType.startsWith('text')
          || contentType === 'application/json') {
        return response.text()
      } else {
        return response.arrayBuffer()
      }
    })
}

/* Handle fetching an unencrypted file, its associated signature
 *  and then validate it. Handles both multi-player reads and reads
 *  from own storage.
 * @private
 * @ignore
 */
function getFileSignedUnencrypted(path: string, opt: GetFileOptions, caller?: UserSession) {
  // future optimization note:
  //    in the case of _multi-player_ reads, this does a lot of excess
  //    profile lookups to figure out where to read files
  //    do browsers cache all these requests if Content-Cache is set?
  return Promise.all(
    [getFileContents(path, opt.app, opt.username, opt.zoneFileLookupURL, false, caller),
     getFileContents(`${path}${SIGNATURE_FILE_SUFFIX}`, opt.app, opt.username,
                     opt.zoneFileLookupURL, true, caller),
     getGaiaAddress(opt.app, opt.username, opt.zoneFileLookupURL, caller)]
  )
    .then(([fileContents, signatureContents, gaiaAddress]) => {
      if (!fileContents) {
        return fileContents
      }
      if (!gaiaAddress) {
        throw new SignatureVerificationError('Failed to get gaia address for verification of: '
                                             + `${path}`)
      }
      if (!signatureContents || typeof signatureContents !== 'string') {
        throw new SignatureVerificationError('Failed to obtain signature for file: '
                                             + `${path} -- looked in ${path}${SIGNATURE_FILE_SUFFIX}`)
      }
      let signature
      let publicKey
      try {
        const sigObject = JSON.parse(signatureContents)
        signature = sigObject.signature
        publicKey = sigObject.publicKey
      } catch (err) {
        if (err instanceof SyntaxError) {
          throw new Error('Failed to parse signature content JSON '
                          + `(path: ${path}${SIGNATURE_FILE_SUFFIX})`
                          + ' The content may be corrupted.')
        } else {
          throw err
        }
      }
      const signerAddress = publicKeyToAddress(publicKey)
      if (gaiaAddress !== signerAddress) {
        throw new SignatureVerificationError(`Signer pubkey address (${signerAddress}) doesn't`
                                             + ` match gaia address (${gaiaAddress})`)
      } else if (!verifyECDSA(fileContents, publicKey, signature)) {
        throw new SignatureVerificationError(
          'Contents do not match ECDSA signature: '
            + `path: ${path}, signature: ${path}${SIGNATURE_FILE_SUFFIX}`
        )
      } else {
        return fileContents
      }
    })
}


/* Handle signature verification and decryption for contents which are
 *  expected to be signed and encrypted. This works for single and
 *  multiplayer reads. In the case of multiplayer reads, it uses the
 *  gaia address for verification of the claimed public key.
 * @private
 * @ignore
 */
function handleSignedEncryptedContents(caller: UserSession, path: string, storedContents: string,
                                       app: string, username?: string, zoneFileLookupURL?: string) {
  const appPrivateKey = caller.loadUserData().appPrivateKey
  const appPublicKey = getPublicKeyFromPrivate(appPrivateKey)

  let addressPromise: Promise<string>
  if (username) {
    addressPromise = getGaiaAddress(app, username, zoneFileLookupURL, caller)
  } else {
    const address = publicKeyToAddress(appPublicKey)
    addressPromise = Promise.resolve(address)
  }

  return addressPromise.then((address) => {
    if (!address) {
      throw new SignatureVerificationError('Failed to get gaia address for verification of: '
                                           + `${path}`)
    }
    let sigObject
    try {
      sigObject = JSON.parse(storedContents)
    } catch (err) {
      if (err instanceof SyntaxError) {
        throw new Error('Failed to parse encrypted, signed content JSON. The content may not '
                        + 'be encrypted. If using getFile, try passing'
                        + ' { verify: false, decrypt: false }.')
      } else {
        throw err
      }
    }
    const signature = sigObject.signature
    const signerPublicKey = sigObject.publicKey
    const cipherText = sigObject.cipherText
    const signerAddress = publicKeyToAddress(signerPublicKey)

    if (!signerPublicKey || !cipherText || !signature) {
      throw new SignatureVerificationError(
        'Failed to get signature verification data from file:'
          + ` ${path}`
      )
    } else if (signerAddress !== address) {
      throw new SignatureVerificationError(`Signer pubkey address (${signerAddress}) doesn't`
                                           + ` match gaia address (${address})`)
    } else if (!verifyECDSA(cipherText, signerPublicKey, signature)) {
      throw new SignatureVerificationError('Contents do not match ECDSA signature in file:'
                                           + ` ${path}`)
    } else {
      return caller.decryptContent(cipherText)
    }
  })
}

export interface GetFileUrlOptions {
  /**
   * The Blockstack ID to lookup for multi-player storage. 
   * If not specified, the currently signed in username is used.
   */
  username?: string;
  /**
   * The app to lookup for multi-player storage - defaults to current origin. 
   * @default `window.location.origin` 
   * Only if available in the executing environment, otherwise `undefined`.
   */
  app?: string;
  /**
   * The URL to use for zonefile lookup. If falsey, this will use 
   * the blockstack.js's [[getNameInfo]] function instead. 
   */
  zoneFileLookupURL?: string;
}

/**
 * Used to pass options to [[UserSession.getFile]]
 */
export interface GetFileOptions extends GetFileUrlOptions {
  /**
   * Try to decrypt the data with the app private key.
   * @default true
   */
  decrypt?: boolean;
  /**
   * Whether the content should be verified, only to be used 
   * when [[UserSession.putFile]] was set to `sign = true`.
   * @default false
   */
  verify?: boolean;
}

/**
 * Retrieves the specified file from the app's data store.
 * @param {String} path - the path to the file to read
 * @returns {Promise} that resolves to the raw data in the file
 * or rejects with an error
 */
export function getFile(
  path: string, 
  options?: GetFileOptions,
  caller?: UserSession
) {
  const defaults: GetFileOptions = {
    decrypt: true,
    verify: false,
    username: null,
    app: getGlobalObject('location', { returnEmptyObject: true }).origin,
    zoneFileLookupURL: null
  }
  const opt = Object.assign({}, defaults, options)

  if (!caller) {
    caller = new UserSession()
  }

  // in the case of signature verification, but no
  //  encryption expected, need to fetch _two_ files.
  if (opt.verify && !opt.decrypt) {
    return getFileSignedUnencrypted(path, opt, caller)
  }

  return getFileContents(path, opt.app, opt.username, opt.zoneFileLookupURL, !!opt.decrypt, caller)
    .then<string|ArrayBuffer|Buffer>((storedContents) => {
      if (storedContents === null) {
        return storedContents
      } else if (opt.decrypt && !opt.verify) {
        if (typeof storedContents !== 'string') {
          throw new Error('Expected to get back a string for the cipherText')
        }
        return caller.decryptContent(storedContents)
      } else if (opt.decrypt && opt.verify) {
        if (typeof storedContents !== 'string') {
          throw new Error('Expected to get back a string for the cipherText')
        }
        return handleSignedEncryptedContents(caller, path, storedContents,
                                             opt.app, opt.username, opt.zoneFileLookupURL)
      } else if (!opt.verify && !opt.decrypt) {
        return storedContents
      } else {
        throw new Error('Should be unreachable.')
      }
    })
}

/**
 * Stores the data provided in the app's data store to to the file specified.
 * @param {String} path - the path to store the data in
 * @param {String|Buffer} content - the data to store in the file
 * @return {Promise} that resolves if the operation succeed and rejects
 * if it failed
 */
export async function putFile(
  path: string,
  content: string | Buffer,
  options?: PutFileOptions,
  caller?: UserSession,
): Promise<string> {
  const defaults: PutFileOptions = {
    encrypt: true,
    sign: false,
    contentType: ''
  }

  const opt = Object.assign({}, defaults, options)

  let { contentType } = opt
  if (!contentType) {
    contentType = (typeof (content) === 'string') ? 'text/plain; charset=utf-8' : 'application/octet-stream'
  }

  if (!caller) {
    caller = new UserSession()
  }

  // First, let's figure out if we need to get public/private keys,
  //  or if they were passed in

  let privateKey = ''
  let publicKey = ''
  if (opt.sign) {
    if (typeof (opt.sign) === 'string') {
      privateKey = opt.sign
    } else {
      privateKey = caller.loadUserData().appPrivateKey
    }
  }
  if (opt.encrypt) {
    if (typeof (opt.encrypt) === 'string') {
      publicKey = opt.encrypt
    } else {
      if (!privateKey) {
        privateKey = caller.loadUserData().appPrivateKey
      }
      publicKey = getPublicKeyFromPrivate(privateKey)
    }
  }

  // In the case of signing, but *not* encrypting,
  //   we perform two uploads. So the control-flow
  //   here will return there.
  if (!opt.encrypt && opt.sign) {
    const signatureObject = signECDSA(privateKey, content)
    const signatureContent = JSON.stringify(signatureObject)
    const gaiaHubConfig = await caller.getOrSetLocalGaiaHubConnection()

    try {
      const fileUrls = await Promise.all([
        uploadToGaiaHub(path, content, gaiaHubConfig, contentType),
        uploadToGaiaHub(`${path}${SIGNATURE_FILE_SUFFIX}`,
                        signatureContent, gaiaHubConfig, 'application/json')
      ])
      return fileUrls[0]
    } catch (error) {
      const freshHubConfig = await caller.setLocalGaiaHubConnection()
      const fileUrls = await Promise.all([
        uploadToGaiaHub(path, content, freshHubConfig, contentType),
        uploadToGaiaHub(`${path}${SIGNATURE_FILE_SUFFIX}`,
                        signatureContent, freshHubConfig, 'application/json')
      ])
      return fileUrls[0]
    }
  }

  // In all other cases, we only need one upload.
  if (opt.encrypt && !opt.sign) {
    content = encryptContent(content, { publicKey })
    contentType = 'application/json'
  } else if (opt.encrypt && opt.sign) {
    const cipherText = encryptContent(content, { publicKey })
    const signatureObject = signECDSA(privateKey, cipherText)
    const signedCipherObject = {
      signature: signatureObject.signature,
      publicKey: signatureObject.publicKey,
      cipherText
    }
    content = JSON.stringify(signedCipherObject)
    contentType = 'application/json'
  }
  const gaiaHubConfig = await caller.getOrSetLocalGaiaHubConnection()
  try {
    return await uploadToGaiaHub(path, content, gaiaHubConfig, contentType)
  } catch (error) {
    const freshHubConfig = await caller.setLocalGaiaHubConnection()
    const file = await uploadToGaiaHub(path, content, freshHubConfig, contentType)
    return file
  }
}

/**
 * Deletes the specified file from the app's data store. 
 * @param path - The path to the file to delete.
 * @param options - Optional options object.
 * @param options.wasSigned - Set to true if the file was originally signed
 * in order for the corresponding signature file to also be deleted.
 * @returns Resolves when the file has been removed or rejects with an error.
 */
export async function deleteFile(
  path: string, 
  options?: {
    wasSigned?: boolean;
  },
  caller?: UserSession
) {
  if (!caller) {
    caller = new UserSession()
  }
  const gaiaHubConfig = await caller.getOrSetLocalGaiaHubConnection()
  const opts = Object.assign({}, options)
  if (opts.wasSigned) {
    // If signed, delete both the content file and the .sig file
    try {
      await deleteFromGaiaHub(path, gaiaHubConfig)
      await deleteFromGaiaHub(`${path}${SIGNATURE_FILE_SUFFIX}`, gaiaHubConfig)
    } catch (error) {
      const freshHubConfig = await caller.setLocalGaiaHubConnection()
      await deleteFromGaiaHub(path, freshHubConfig)
      await deleteFromGaiaHub(`${path}${SIGNATURE_FILE_SUFFIX}`, gaiaHubConfig)
    }
  } else {
    try {
      await deleteFromGaiaHub(path, gaiaHubConfig)
    } catch (error) {
      const freshHubConfig = await caller.setLocalGaiaHubConnection()
      await deleteFromGaiaHub(path, freshHubConfig)
    }
  }
}

/**
 * Get the app storage bucket URL
 * @param {String} gaiaHubUrl - the gaia hub URL
 * @param {String} appPrivateKey - the app private key used to generate the app address
 * @returns {Promise} That resolves to the URL of the app index file
 * or rejects if it fails
 */
export function getAppBucketUrl(gaiaHubUrl: string, appPrivateKey: string) {
  return getBucketUrl(gaiaHubUrl, appPrivateKey)
}

/**
 * Loop over the list of files in a Gaia hub, and run a callback on each entry.
 * Not meant to be called by external clients.
 * @param {GaiaHubConfig} hubConfig - the Gaia hub config
 * @param {String | null} page - the page ID
 * @param {number} callCount - the loop count
 * @param {number} fileCount - the number of files listed so far
 * @param {function} callback - the callback to invoke on each file.  If it returns a falsey
 *  value, then the loop stops.  If it returns a truthy value, the loop continues.
 * @returns {Promise} that resolves to the number of files listed.
 * @private
 * @ignore
 */
async function listFilesLoop(
  caller: UserSession,
  hubConfig: GaiaHubConfig | null,
  page: string | null,
  callCount: number,
  fileCount: number,
  callback: (name: string) => boolean
): Promise<number> {
  if (callCount > 65536) {
    // this is ridiculously huge, and probably indicates
    // a faulty Gaia hub anyway (e.g. on that serves endless data)
    throw new Error('Too many entries to list')
  }

  hubConfig = hubConfig || await caller.getOrSetLocalGaiaHubConnection()
  let response: Response
  try {
    const pageRequest = JSON.stringify({ page })
    const fetchOptions = {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'Content-Length': `${pageRequest.length}`,
        Authorization: `bearer ${hubConfig.token}`
      },
      body: pageRequest
    }
    response = await fetchPrivate(`${hubConfig.server}/list-files/${hubConfig.address}`, fetchOptions)
    if (!response.ok) {
      throw new Error(`listFiles failed with HTTP status ${response.status}`)
    }
  } catch (error) {
    // If error occurs on the first call, perform a gaia re-connection and retry.
    // Same logic as other gaia requests (putFile, getFile, etc).
    if (callCount === 0) {
      const freshHubConfig = await caller.setLocalGaiaHubConnection()
      return listFilesLoop(caller, freshHubConfig, page, callCount + 1, 0, callback)
    }
    throw error
  }

  const responseText = await response.text()
  const responseJSON = JSON.parse(responseText)
  const entries = responseJSON.entries
  const nextPage = responseJSON.page
  if (entries === null || entries === undefined) {
    // indicates a misbehaving Gaia hub or a misbehaving driver
    // (i.e. the data is malformed)
    throw new Error('Bad listFiles response: no entries')
  }
  for (let i = 0; i < entries.length; i++) {
    const rc = callback(entries[i])
    if (!rc) {
      // callback indicates that we're done
      return fileCount + i
    }
  }
  if (nextPage && entries.length > 0) {
    // keep going -- have more entries
    return listFilesLoop(
      caller, hubConfig, nextPage, callCount + 1, fileCount + entries.length, callback
    )
  } else {
    // no more entries -- end of data
    return fileCount + entries.length
  }
}

/**
 * List the set of files in this application's Gaia storage bucket.
 * @param {function} callback - a callback to invoke on each named file that
 * returns `true` to continue the listing operation or `false` to end it
 * @return {Promise} that resolves to the number of files listed
 */
export function listFiles(
  callback: (name: string) => boolean,
  caller?: UserSession
): Promise<number> {
  caller = caller || new UserSession()
  return listFilesLoop(caller, null, null, 0, 0, callback)
}

export { connectToGaiaHub, uploadToGaiaHub, BLOCKSTACK_GAIA_HUB_LABEL }