import os
import strutils
import pkg/chronos
import pkg/chronicles
import pkg/questionable
import pkg/confutils/defs
import pkg/stew/io2
import pkg/ethers

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

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

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

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

  trace "Initialized prover backend from cli config"
  success(utils.initializeCircomBackend(
    $config.circomR1cs,
    $config.circomWasm,
    $config.circomZkey))

proc r1csFilePath(config: CodexConf): string =
  config.circuitDir / "proof_main.r1cs"

proc wasmFilePath(config: CodexConf): string =
  config.circuitDir / "proof_main.wasm"

proc zkeyFilePath(config: CodexConf): string =
  config.circuitDir / "proof_main.zkey"

proc initializeFromCircuitDirFiles(
  config: CodexConf,
  utils: BackendUtils): ?!AnyBackend =
  if fileExists(config.r1csFilePath) and
    fileExists(config.wasmFilePath) and
    fileExists(config.zkeyFilePath):
    trace "Initialized prover backend from local files"
    return success(utils.initializeCircomBackend(
      config.r1csFilePath,
      config.wasmFilePath,
      config.zkeyFilePath))

  failure("Circuit files not found")

proc suggestDownloadTool(config: CodexConf) =
  without address =? config.marketplaceAddress:
    raise (ref Defect)(msg: "Proving backend initializing while marketplace address not set.")

  let
    tokens = [
      "cirdl",
      "\"" & $config.circuitDir & "\"",
      config.ethProvider,
      $address
    ]
    instructions = "'./" & tokens.join(" ") & "'"

  warn "Proving circuit files are not found. Please run the following to download them:", instructions

proc initializeBackend*(
  config: CodexConf,
  utils: BackendUtils = BackendUtils()): ?!AnyBackend =

  without backend =? initializeFromConfig(config, utils), cliErr:
    info "Could not initialize prover backend from CLI options...", msg = cliErr.msg
    without backend =? initializeFromCircuitDirFiles(config, utils), localErr:
      info "Could not initialize prover backend from circuit dir files...", msg = localErr.msg
      suggestDownloadTool(config)
      return failure("CircuitFilesNotFound")
    # Unexpected: value of backend does not survive leaving each scope. (definition does though...)
    return success(backend)
  return success(backend)