const { log, output, input, META } = require('proc-log')
const { explain } = require('./explain-eresolve.js')
const { formatWithOptions } = require('./format')

// This is the general approach to color:
// Eventually this will be exposed somewhere we can refer to these by name.
// Foreground colors only. Never set the background color.
/*
 * Black # (Don't use)
 * Red # Danger
 * Green # Success
 * Yellow # Warning
 * Blue # Accent
 * Magenta # Done
 * Cyan # Emphasis
 * White # (Don't use)
 */

// Translates log levels to chalk colors
const COLOR_PALETTE = ({ chalk: c }) => ({
  heading: c.bold,
  title: c.blueBright,
  timing: c.magentaBright,
  // loglevels
  error: c.red,
  warn: c.yellow,
  notice: c.cyanBright,
  http: c.green,
  info: c.cyan,
  verbose: c.blue,
  silly: c.blue.dim,
})

const LEVEL_OPTIONS = {
  silent: {
    index: 0,
  },
  error: {
    index: 1,
  },
  warn: {
    index: 2,
  },
  notice: {
    index: 3,
  },
  http: {
    index: 4,
  },
  info: {
    index: 5,
  },
  verbose: {
    index: 6,
  },
  silly: {
    index: 7,
  },
}

const LEVEL_METHODS = {
  ...LEVEL_OPTIONS,
  [log.KEYS.timing]: {
    show: ({ timing, index }) => !!timing && index !== 0,
  },
}

const setBlocking = (stream) => {
  // Copied from https://github.com/yargs/set-blocking
  // https://raw.githubusercontent.com/yargs/set-blocking/master/LICENSE.txt
  /* istanbul ignore next - we trust that this works */
  if (stream._handle && stream.isTTY && typeof stream._handle.setBlocking === 'function') {
    stream._handle.setBlocking(true)
  }
  return stream
}

// This is the key that is returned to the user for errors
const ERROR_KEY = 'error'
// This is the key producers use to indicate that there is a json error that should be merged into the finished output
const JSON_ERROR_KEY = 'jsonError'

const isPlainObject = (v) => v && typeof v === 'object' && !Array.isArray(v)

const getArrayOrObject = (items) => {
  if (items.length) {
    const foundNonObject = items.find(o => !isPlainObject(o))
    // Non-objects and arrays cant be merged, so just return the first item
    if (foundNonObject) {
      return foundNonObject
    }
    // We use objects with 0,1,2,etc keys to merge array
    if (items.every((o, i) => Object.hasOwn(o, i))) {
      return Object.assign([], ...items)
    }
  }
  // Otherwise its an object with all object items merged together
  return Object.assign({}, ...items.filter(o => isPlainObject(o)))
}

const getJsonBuffer = ({ [JSON_ERROR_KEY]: metaError }, buffer) => {
  const items = []
  // meta also contains the meta object passed to flush
  const errors = metaError ? [metaError] : []
  // index 1 is the meta, 2 is the logged argument
  for (const [, { [JSON_ERROR_KEY]: error }, obj] of buffer) {
    if (obj) {
      items.push(obj)
    }
    if (error) {
      errors.push(error)
    }
  }

  if (!items.length && !errors.length) {
    return null
  }

  const res = getArrayOrObject(items)

  // This skips any error checking since we can only set an error property on an object that can be stringified
  // XXX(BREAKING_CHANGE): remove this in favor of always returning an object with result and error keys
  if (isPlainObject(res) && errors.length) {
    // This is not ideal.
    // JSON output has always been keyed at the root with an `error` key, so we cant change that without it being a breaking change. At the same time some commands output arbitrary keys at the top level of the output, such as package names.
    // So the output could already have the same key. The choice here is to overwrite it with our error since that is (probably?) more important.
    // XXX(BREAKING_CHANGE): all json output should be keyed under well known keys, eg `result` and `error`
    if (res[ERROR_KEY]) {
      log.warn('', `overwriting existing ${ERROR_KEY} on json output`)
    }
    res[ERROR_KEY] = getArrayOrObject(errors)
  }

  return res
}

const withMeta = (handler) => (level, ...args) => {
  let meta = {}
  const last = args.at(-1)
  if (last && typeof last === 'object' && Object.hasOwn(last, META)) {
    meta = args.pop()
  }
  return handler(level, meta, ...args)
}

class Display {
  #logState = {
    buffering: true,
    buffer: [],
  }

  #outputState = {
    buffering: true,
    buffer: [],
  }

  // colors
  #noColorChalk
  #stdoutChalk
  #stdoutColor
  #stderrChalk
  #stderrColor
  #logColors

  // progress
  #progress

  // options
  #command
  #levelIndex
  #timing
  #json
  #heading
  #silent

  // display streams
  #stdout
  #stderr

  constructor ({ stdout, stderr }) {
    this.#stdout = setBlocking(stdout)
    this.#stderr = setBlocking(stderr)

    // Handlers are set immediately so they can buffer all events
    process.on('log', this.#logHandler)
    process.on('output', this.#outputHandler)
    process.on('input', this.#inputHandler)
    this.#progress = new Progress({ stream: stderr })
  }

  off () {
    process.off('log', this.#logHandler)
    this.#logState.buffer.length = 0
    process.off('output', this.#outputHandler)
    this.#outputState.buffer.length = 0
    process.off('input', this.#inputHandler)
    this.#progress.off()
  }

  get chalk () {
    return {
      noColor: this.#noColorChalk,
      stdout: this.#stdoutChalk,
      stderr: this.#stderrChalk,
    }
  }

  async load ({
    command,
    heading,
    json,
    loglevel,
    progress,
    stderrColor,
    stdoutColor,
    timing,
    unicode,
  }) {
    const [{ Chalk }, { createSupportsColor }] = await Promise.all([
      import('chalk'),
      import('supports-color'),
    ])
    // We get the chalk level based on a null stream, meaning chalk will only use what it knows about the environment to get color support since we already determined in our definitions that we want to show colors.
    const level = Math.max(createSupportsColor(null).level, 1)
    this.#noColorChalk = new Chalk({ level: 0 })
    this.#stdoutColor = stdoutColor
    this.#stdoutChalk = stdoutColor ? new Chalk({ level }) : this.#noColorChalk
    this.#stderrColor = stderrColor
    this.#stderrChalk = stderrColor ? new Chalk({ level }) : this.#noColorChalk
    this.#logColors = COLOR_PALETTE({ chalk: this.#stderrChalk })

    this.#command = command
    this.#levelIndex = LEVEL_OPTIONS[loglevel].index
    this.#timing = timing
    this.#json = json
    this.#heading = heading
    this.#silent = this.#levelIndex <= 0

    // Emit resume event on the logs which will flush output
    log.resume()
    output.flush()
    this.#progress.load({
      unicode,
      enabled: !!progress && !this.#silent,
    })
  }

  // STREAM WRITES

  // Write formatted and (non-)colorized output to streams
  #write (stream, options, ...args) {
    const colors = stream === this.#stdout ? this.#stdoutColor : this.#stderrColor
    const value = formatWithOptions({ colors, ...options }, ...args)
    this.#progress.write(() => stream.write(value))
  }

  // HANDLERS

  // Arrow function assigned to a private class field so it can be passed directly as a listener and still reference "this"
  #logHandler = withMeta((level, meta, ...args) => {
    switch (level) {
      case log.KEYS.resume:
        this.#logState.buffering = false
        this.#logState.buffer.forEach((item) => this.#tryWriteLog(...item))
        this.#logState.buffer.length = 0
        break

      case log.KEYS.pause:
        this.#logState.buffering = true
        break

      default:
        if (this.#logState.buffering) {
          this.#logState.buffer.push([level, meta, ...args])
        } else {
          this.#tryWriteLog(level, meta, ...args)
        }
        break
    }
  })

  // Arrow function assigned to a private class field so it can be passed directly as a listener and still reference "this"
  #outputHandler = withMeta((level, meta, ...args) => {
    this.#json = typeof meta.json === 'boolean' ? meta.json : this.#json
    switch (level) {
      case output.KEYS.flush: {
        this.#outputState.buffering = false
        if (this.#json) {
          const json = getJsonBuffer(meta, this.#outputState.buffer)
          if (json) {
            this.#writeOutput(output.KEYS.standard, meta, JSON.stringify(json, null, 2))
          }
        } else {
          this.#outputState.buffer.forEach((item) => this.#writeOutput(...item))
        }
        this.#outputState.buffer.length = 0
        break
      }

      case output.KEYS.buffer:
        this.#outputState.buffer.push([output.KEYS.standard, meta, ...args])
        break

      default:
        if (this.#outputState.buffering) {
          this.#outputState.buffer.push([level, meta, ...args])
        } else {
          // XXX: Check if the argument looks like a run-script banner.  This should be replaced with proc-log.META in @npmcli/run-script
          if (typeof args[0] === 'string' && args[0].startsWith('\n> ') && args[0].endsWith('\n')) {
            if (this.#silent || ['exec', 'explore'].includes(this.#command)) {
              // Silent mode and some specific commands always hide run script banners
              break
            } else if (this.#json) {
              // In json mode, change output to stderr since we don't want to break json parsing on stdout if the user is piping to jq or something.
              // XXX: in a future (breaking?) change it might make sense for run-script to always output these banners with proc-log.output.error if we think they align closer with "logging" instead of "output".
              level = output.KEYS.error
            }
          }
          this.#writeOutput(level, meta, ...args)
        }
        break
    }
  })

  #inputHandler = withMeta((level, meta, ...args) => {
    switch (level) {
      case input.KEYS.start:
        log.pause()
        this.#outputState.buffering = true
        this.#progress.off()
        break

      case input.KEYS.end:
        log.resume()
        output.flush()
        this.#progress.resume()
        break

      case input.KEYS.read: {
        // The convention when calling input.read is to pass in a single fn that returns the promise to await. resolve and reject are provided by proc-log.
        const [res, rej, p] = args
        return input.start(() => p()
          .then(res)
          .catch(rej)
          // Any call to procLog.input.read will render a prompt to the user, so we always add a single newline of output to stdout to move the cursor to the next line.
          .finally(() => output.standard('')))
      }
    }
  })

  // OUTPUT

  #writeOutput (level, meta, ...args) {
    switch (level) {
      case output.KEYS.standard:
        this.#write(this.#stdout, meta, ...args)
        break

      case output.KEYS.error:
        this.#write(this.#stderr, meta, ...args)
        break
    }
  }

  // LOGS

  #tryWriteLog (level, meta, ...args) {
    try {
      // Also (and this is a really inexcusable kludge), we patch the log.warn() method so that when we see a peerDep override explanation from Arborist, we can replace the object with a highly abbreviated explanation of what's being overridden.
      // TODO: this could probably be moved to arborist now that display is refactored
      const [heading, message, expl] = args
      if (level === log.KEYS.warn && heading === 'ERESOLVE' && expl && typeof expl === 'object') {
        this.#writeLog(level, meta, heading, message)
        this.#writeLog(level, meta, '', explain(expl, this.#stderrChalk, 2))
        return
      }
      this.#writeLog(level, meta, ...args)
    } catch (ex) {
      try {
        // if it crashed once, it might again!
        this.#writeLog(log.KEYS.verbose, meta, '', `attempt to log crashed`, ...args, ex)
      } catch (ex2) {
        // This happens if the object has an inspect method that crashes so just console.error with the errors but don't do anything else that might error again.
        // eslint-disable-next-line no-console
        console.error(`attempt to log crashed`, ex, ex2)
      }
    }
  }

  #writeLog (level, meta, ...args) {
    const levelOpts = LEVEL_METHODS[level]
    const show = levelOpts.show ?? (({ index }) => levelOpts.index <= index)
    const force = meta.force && !this.#silent

    if (force || show({ index: this.#levelIndex, timing: this.#timing })) {
      // this mutates the array so we can pass args directly to format later
      const title = args.shift()
      const prefix = [
        this.#logColors.heading(this.#heading),
        this.#logColors[level](level),
        title ? this.#logColors.title(title) : null,
      ]
      const writeOpts = { prefix }
      // notice logs typically come from `npm-notice` headers in responses.  Some of them have 2fa login links so we skip redaction.
      if (level === 'notice') {
        writeOpts.redact = false
      }
      this.#write(this.#stderr, writeOpts, ...args)
    }
  }
}

class Progress {
  // Taken from https://github.com/sindresorhus/cli-spinners
  // MIT License
  // Copyright (c) Sindre Sorhus <sindresorhus@gmail.com> (https://sindresorhus.com)
  static dots = { duration: 80, frames: ['⠋', '⠙', '⠹', '⠸', '⠼', '⠴', '⠦', '⠧', '⠇', '⠏'] }
  static lines = { duration: 130, frames: ['-', '\\', '|', '/'] }

  #enabled = false
  #frameIndex = 0
  #interval
  #lastUpdate = 0
  #spinner
  #stream
  // Initial timeout to wait to start rendering
  #timeout
  #rendered = false

  // We are rendering if enabled option is set and we are not waiting for the render timeout
  get #rendering () {
    return this.#enabled && !this.#timeout
  }

  // We are spinning if enabled option is set and the render interval has been set
  get #spinning () {
    return this.#enabled && this.#interval
  }

  constructor ({ stream }) {
    this.#stream = stream
  }

  load ({ enabled, unicode }) {
    this.#enabled = enabled
    this.#spinner = unicode ? Progress.dots : Progress.lines
    // Wait 200 ms so we don't render the spinner for short durations
    this.#timeout = setTimeout(() => {
      this.#timeout = null
      this.#render()
    }, 200)
    // Make sure this timeout does not keep the process open
    this.#timeout.unref()
  }

  off () {
    if (!this.#enabled) {
      return
    }
    clearTimeout(this.#timeout)
    this.#timeout = null
    clearInterval(this.#interval)
    this.#interval = null
    this.#frameIndex = 0
    this.#lastUpdate = 0
    this.#clearSpinner()
  }

  resume () {
    this.#render(true)
  }

  // If we are currently rendering the spinner we clear it before writing our line and then re-render the spinner after.
  // If not then all we need to do is write the line.
  write (write) {
    if (this.#spinning) {
      this.#clearSpinner()
    }
    write()
    if (this.#spinning) {
      this.#render()
    }
  }

  #render (resuming) {
    if (!this.#rendering) {
      return
    }
    // We always attempt to render immediately but we only request to move to the next frame if it has been longer than our spinner frame duration since our last update
    this.#renderFrame(Date.now() - this.#lastUpdate >= this.#spinner.duration, resuming)
    if (!this.#interval) {
      this.#interval = setInterval(() => this.#renderFrame(true), this.#spinner.duration)
      // Make sure this timeout does not keep the process open
      this.#interval.unref()
    }
    this.#interval.refresh()
  }

  #renderFrame (next, resuming) {
    if (next) {
      this.#lastUpdate = Date.now()
      this.#frameIndex++
      if (this.#frameIndex >= this.#spinner.frames.length) {
        this.#frameIndex = 0
      }
    }
    if (!resuming) {
      this.#clearSpinner()
    }
    this.#stream.write(this.#spinner.frames[this.#frameIndex])
    this.#rendered = true
  }

  #clearSpinner () {
    if (!this.#rendered) {
      return
    }
    // Move to the start of the line and clear the rest of the line
    this.#stream.cursorTo(0)
    this.#stream.clearLine(1)
    this.#rendered = false
  }
}

module.exports = Display
