import os
import pkg/chronos
import pkg/questionable
import pkg/confutils/defs
import pkg/stew/io2

import ../../conf
import ./backends

proc initializeCircomBackend(
  r1csFile: string,
  wasmFile: string,
  zKeyFile: string
): AnyBackend =
  CircomCompat.init(r1csFile, wasmFile, zKeyFile)

proc initializeFromConfig(
  config: CodexConf): ?!AnyBackend =
  if not fileAccessible($config.circomR1cs, {AccessFlags.Read}) and
    endsWith($config.circomR1cs, ".r1cs"):
    return failure("Circom R1CS file not accessible")

  if not fileAccessible($config.circomWasm, {AccessFlags.Read}) and
    endsWith($config.circomWasm, ".wasm"):
    return failure("Circom wasm file not accessible")

  if not fileAccessible($config.circomZkey, {AccessFlags.Read}) and
    endsWith($config.circomZkey, ".zkey"):
    return failure("Circom zkey file not accessible")

  success(initializeCircomBackend(
    $config.circomR1cs,
    $config.circomWasm,
    $config.circomZkey))

proc r1csFilePath(config: CodexConf): string =
  config.dataDir / "circuit.r1cs"

proc wasmFilePath(config: CodexConf): string =
  config.dataDir / "circuit.wasm"

proc zkeyFilePath(config: CodexConf): string =
  config.dataDir / "circuit.zkey"

proc initializeFromCeremonyFiles(config: CodexConf): ?!AnyBackend =
  if fileExists(config.r1csFilePath) and
    fileExists(config.wasmFilePath) and
    fileExists(config.zkeyFilePath):
    return success(initializeCircomBackend(
      config.r1csFilePath,
      config.wasmFilePath,
      config.zkeyFilePath))

  failure("Ceremony files not found")

proc initializeFromCeremonyUrl(
  config: CodexConf,
  proofCeremonyUrl: ?string): Future[?!AnyBackend] {.async.} =

  # download the ceremony url
  # unzip it

  without backend =? initializeFromCeremonyFiles(config), err:
    return failure(err)
  return success(backend)

proc initializeBackend*(
  config: CodexConf,
  proofCeremonyUrl: ?string): Future[?!AnyBackend] {.async.} =

  without backend =? initializeFromConfig(config), cliErr:
    info "Could not initialize prover backend from CLI options...", msg = cliErr.msg
    without backend =? initializeFromCeremonyFiles(config), localErr:
      info "Could not initialize prover backend from local files...", msg = localErr.msg
      without backend =? (await initializeFromCeremonyUrl(config, proofCeremonyUrl)), urlErr:
        warn "Could not initialize prover backend from ceremony url...", msg = urlErr.msg
        return failure(urlErr)
  return success(backend)