/* Imports: External */
import * as fs from 'fs'
import * as path from 'path'
import fetch from 'node-fetch'
import { subtask, extendEnvironment } from 'hardhat/config'
import { getCompilersDir } from 'hardhat/internal/util/global-dir'
import { Artifacts } from 'hardhat/internal/artifacts'
import {
  TASK_COMPILE_SOLIDITY_RUN_SOLCJS,
  TASK_COMPILE_SOLIDITY_RUN_SOLC,
} from 'hardhat/builtin-tasks/task-names'

/* Imports: Internal */
import './type-extensions'

const OPTIMISM_SOLC_BIN_URL =
  'https://raw.githubusercontent.com/ethereum-optimism/solc-bin/gh-pages/bin'

// I figured this was a reasonably modern default, but not sure if this is too new. Maybe we can
// default to 0.6.X instead?
const DEFAULT_OVM_SOLC_VERSION = '0.7.6'

/**
 * Find or generate an OVM soljson.js compiler file and return the path of this file.
 * We pass the path to this file into hardhat.
 * @param version Solidity compiler version to get a path for in the format `X.Y.Z`.
 * @return Path to the downloaded soljson.js file.
 */
const getOvmSolcPath = async (version: string): Promise<string> => {
  // If __DANGEROUS_OVM_IGNORE_ERRORS__ env var is not undefined we append the -no-errors suffix to the solc version.
  if (process.env.__DANGEROUS_OVM_IGNORE_ERRORS__) {
    console.log('\n\n__DANGEROUS_OVM_IGNORE_ERRORS__ IS ENABLED!\n\n')
    version += '-no_errors'
  }

  // First, check to see if we've already downloaded this file. Hardhat gives us a folder to use as
  // a compiler cache, so we'll just be nice and use an `ovm` subfolder.
  const ovmCompilersCache = path.join(await getCompilersDir(), 'ovm')

  // Need to create the OVM compiler cache folder if it doesn't already exist.
  if (!fs.existsSync(ovmCompilersCache))
    [fs.mkdirSync(ovmCompilersCache, { recursive: true })]

  // Check to see if we already have this compiler version downloaded. We store the cached files at
  // `X.Y.Z.js`. If it already exists, just return that instead of downloading a new one.
  const cachedCompilerPath = path.join(ovmCompilersCache, `${version}.js`)
  if (fs.existsSync(cachedCompilerPath)) {
    return cachedCompilerPath
  }

  console.log(`Downloading OVM compiler version ${version}`)

  // We don't have a cache, so we'll download this file from GitHub. Currently stored at
  // ethereum-optimism/solc-bin.
  const compilerContentResponse = await fetch(
    OPTIMISM_SOLC_BIN_URL + `/soljson-v${version}.js`
  )

  // Throw if this request failed, e.g., 404 because of an invalid version.
  if (!compilerContentResponse.ok) {
    throw new Error(
      `Unable to download OVM compiler version ${version}. Are you sure that version exists?`
    )
  }

  // Otherwise, write the content to the cache. We probably want to do some sort of hash
  // verification against these files but it's OK for now. The real "TODO" here is to instead
  // figure out how to properly extend and/or hack Hardat's CompilerDownloader class.
  const compilerContent = await compilerContentResponse.text()
  fs.writeFileSync(cachedCompilerPath, compilerContent)

  return cachedCompilerPath
}

subtask(
  TASK_COMPILE_SOLIDITY_RUN_SOLC,
  async (args: { input: any; solcPath: string }, hre, runSuper) => {
    if (hre.network.ovm !== true) {
      return runSuper(args)
    }

    // Just some silly sanity checks, make sure we have a solc version to download. Our format is
    // `X.Y.Z` (for now).
    let ovmSolcVersion = DEFAULT_OVM_SOLC_VERSION
    if (hre.config?.ovm?.solcVersion) {
      ovmSolcVersion = hre.config.ovm.solcVersion
    }

    // Get a path to a soljson file.
    const ovmSolcPath = await getOvmSolcPath(ovmSolcVersion)

    // These objects get fed into the compiler. We're creating two of these because we need to
    // throw one into the OVM compiler and another into the EVM compiler. Users are able to prevent
    // certain files from being compiled by the OVM compiler by adding "// @unsupported: ovm"
    // somewhere near the top of their file.
    const ovmInput = {
      language: 'Solidity',
      sources: {},
      settings: args.input.settings,
    }

    // Separate the EVM and OVM inputs.
    for (const file of Object.keys(args.input.sources)) {
      // Ignore any contract that has this tag.
      if (!args.input.sources[file].content.includes('// @unsupported: ovm')) {
        ovmInput.sources[file] = args.input.sources[file]
      }
    }

    // Build both inputs separately.
    const ovmOutput = await hre.run(TASK_COMPILE_SOLIDITY_RUN_SOLCJS, {
      input: ovmInput,
      solcJsPath: ovmSolcPath,
    })

    // Just doing this to add some extra useful information to any errors in the OVM compiler output.
    ovmOutput.errors = (ovmOutput.errors || []).map((error: any) => {
      if (error.severity === 'error') {
        error.formattedMessage = `OVM Compiler Error (insert "// @unsupported: ovm" if you don't want this file to be compiled for the OVM):\n ${error.formattedMessage}`
      }

      return error
    })

    return ovmOutput
  }
)

extendEnvironment((hre) => {
  if (hre.network.config.ovm) {
    hre.network.ovm = hre.network.config.ovm

    let artifactsPath = hre.config.paths.artifacts
    if (!artifactsPath.endsWith('-ovm')) {
      artifactsPath = artifactsPath + '-ovm'
    }

    let cachePath = hre.config.paths.cache
    if (!cachePath.endsWith('-ovm')) {
      cachePath = cachePath + '-ovm'
    }

    // Forcibly update the artifacts object.
    hre.config.paths.artifacts = artifactsPath
    hre.config.paths.cache = cachePath
    ;(hre as any).artifacts = new Artifacts(artifactsPath)
  }
})
