const { resolve, relative, sep } = require('path')
const archy = require('archy')
const { breadth } = require('treeverse')
const npa = require('npm-package-arg')
const { output } = require('proc-log')
const ArboristWorkspaceCmd = require('../arborist-cmd.js')
const localeCompare = require('@isaacs/string-locale-compare')('en')

const relativePrefix = `.${sep}`

const _depth = Symbol('depth')
const _dedupe = Symbol('dedupe')
const _filteredBy = Symbol('filteredBy')
const _include = Symbol('include')
const _invalid = Symbol('invalid')
const _name = Symbol('name')
const _missing = Symbol('missing')
const _parent = Symbol('parent')
const _problems = Symbol('problems')
const _required = Symbol('required')
const _type = Symbol('type')

class LS extends ArboristWorkspaceCmd {
  static description = 'List installed packages'
  static name = 'ls'
  static usage = ['<package-spec>']
  static params = [
    'all',
    'json',
    'long',
    'parseable',
    'global',
    'depth',
    'omit',
    'include',
    'link',
    'package-lock-only',
    'unicode',
    ...super.params,
  ]

  // TODO
  /* istanbul ignore next */
  static async completion (opts, npm) {
    const completion = require('../utils/installed-deep.js')
    return completion(npm, opts)
  }

  async exec (args) {
    const all = this.npm.config.get('all')
    const chalk = this.npm.chalk
    const depth = this.npm.config.get('depth')
    const global = this.npm.global
    const json = this.npm.config.get('json')
    const link = this.npm.config.get('link')
    const long = this.npm.config.get('long')
    const omit = this.npm.flatOptions.omit
    const parseable = this.npm.config.get('parseable')
    const unicode = this.npm.config.get('unicode')
    const packageLockOnly = this.npm.config.get('package-lock-only')
    const workspacesEnabled = this.npm.flatOptions.workspacesEnabled

    const path = global ? resolve(this.npm.globalDir, '..') : this.npm.prefix

    const Arborist = require('@npmcli/arborist')

    const arb = new Arborist({
      global,
      ...this.npm.flatOptions,
      legacyPeerDeps: false,
      path,
    })
    const tree = await this.initTree({ arb, args, packageLockOnly })

    // filters by workspaces nodes when using -w <workspace-name>
    // We only have to filter the first layer of edges, so we don't
    // explore anything that isn't part of the selected workspace set.
    let wsNodes
    if (this.workspaceNames && this.workspaceNames.length) {
      wsNodes = arb.workspaceNodes(tree, this.workspaceNames)
    }
    const filterBySelectedWorkspaces = edge => {
      if (!workspacesEnabled
        && edge.from.isProjectRoot
        && edge.to.isWorkspace
      ) {
        return false
      }

      if (!wsNodes || !wsNodes.length) {
        return true
      }

      if (this.npm.flatOptions.includeWorkspaceRoot
          && edge.to && !edge.to.isWorkspace) {
        return true
      }

      if (edge.from.isProjectRoot) {
        return (edge.to
          && edge.to.isWorkspace
          && wsNodes.includes(edge.to.target))
      }

      return true
    }

    const seenItems = new Set()
    const seenNodes = new Map()
    const problems = new Set()

    // defines special handling of printed depth when filtering with args
    const filterDefaultDepth = depth === null ? Infinity : depth
    const depthToPrint = (all || args.length)
      ? filterDefaultDepth
      : (depth || 0)

    // add root node of tree to list of seenNodes
    seenNodes.set(tree.path, tree)

    // tree traversal happens here, using treeverse.breadth
    const result = await breadth({
      tree,
      // recursive method, `node` is going to be the current elem (starting from
      // the `tree` obj) that was just visited in the `visit` method below
      // `nodeResult` is going to be the returned `item` from `visit`
      getChildren (node, nodeResult) {
        const seenPaths = new Set()
        const workspace = node.isWorkspace
        const currentDepth = workspace ? 0 : node[_depth]
        const shouldSkipChildren =
          !(node instanceof Arborist.Node) || (currentDepth > depthToPrint)
        return (shouldSkipChildren)
          ? []
          : [...(node.target).edgesOut.values()]
            .filter(filterBySelectedWorkspaces)
            .filter(currentDepth === 0 ? filterByEdgesTypes({
              link,
              omit,
            }) : () => true)
            .map(mapEdgesToNodes({ seenPaths }))
            .concat(appendExtraneousChildren({ node, seenPaths }))
            .sort(sortAlphabetically)
            .map(augmentNodesWithMetadata({
              args,
              currentDepth,
              nodeResult,
              seenNodes,
            }))
      },
      // visit each `node` of the `tree`, returning an `item` - these are
      // the elements that will be used to build the final output
      visit (node) {
        node[_problems] = getProblems(node, { global })

        const item = json
          ? getJsonOutputItem(node, { global, long })
          : parseable
            ? null
            : getHumanOutputItem(node, { args, chalk, global, long })

        // loop through list of node problems to add them to global list
        if (node[_include]) {
          for (const problem of node[_problems]) {
            problems.add(problem)
          }
        }

        seenItems.add(item)

        // return a promise so we don't blow the stack
        return Promise.resolve(item)
      },
    })

    // handle the special case of a broken package.json in the root folder
    const [rootError] = tree.errors.filter(e =>
      e.code === 'EJSONPARSE' && e.path === resolve(path, 'package.json'))

    output.buffer(
      json ? jsonOutput({ path, problems, result, rootError, seenItems }) :
      parseable ? parseableOutput({ seenNodes, global, long }) :
      humanOutput({ chalk, result, seenItems, unicode })
    )

    // if filtering items, should exit with error code on no results
    if (result && !result[_include] && args.length) {
      process.exitCode = 1
    }

    if (rootError) {
      throw Object.assign(
        new Error('Failed to parse root package.json'),
        { code: 'EJSONPARSE' }
      )
    }

    const shouldThrow = problems.size &&
      ![...problems].every(problem => problem.startsWith('extraneous:'))

    if (shouldThrow) {
      throw Object.assign(
        new Error([...problems].join('\n')),
        { code: 'ELSPROBLEMS' }
      )
    }
  }

  async initTree ({ arb, args, packageLockOnly }) {
    const tree = await (
      packageLockOnly
        ? arb.loadVirtual()
        : arb.loadActual()
    )

    tree[_include] = args.length === 0
    tree[_depth] = 0

    return tree
  }
}

module.exports = LS

const isGitNode = (node) => {
  if (!node.resolved) {
    return
  }

  try {
    const { type } = npa(node.resolved)
    return type === 'git' || type === 'hosted'
  } catch (err) {
    return false
  }
}

const isOptional = (node) =>
  node[_type] === 'optional' || node[_type] === 'peerOptional'

const isExtraneous = (node, { global }) =>
  node.extraneous && !global

const getProblems = (node, { global }) => {
  const problems = new Set()

  if (node[_missing] && !isOptional(node)) {
    problems.add(`missing: ${node.pkgid}, required by ${node[_missing]}`)
  }

  if (node[_invalid]) {
    problems.add(`invalid: ${node.pkgid} ${node.path}`)
  }

  if (isExtraneous(node, { global })) {
    problems.add(`extraneous: ${node.pkgid} ${node.path}`)
  }

  return problems
}

// annotates _parent and _include metadata into the resulting
// item obj allowing for filtering out results during output
const augmentItemWithIncludeMetadata = (node, item) => {
  item[_parent] = node[_parent]
  item[_include] = node[_include]

  // append current item to its parent.nodes which is the
  // structure expected by archy in order to print tree
  if (node[_include]) {
    // includes all ancestors of included node
    let p = node[_parent]
    while (p) {
      p[_include] = true
      p = p[_parent]
    }
  }

  return item
}

const getHumanOutputItem = (node, { args, chalk, global, long }) => {
  const { pkgid, path } = node
  const workspacePkgId = chalk.blueBright(pkgid)
  let printable = node.isWorkspace ? workspacePkgId : pkgid

  // special formatting for top-level package name
  if (node.isRoot) {
    const hasNoPackageJson = !Object.keys(node.package).length
    if (hasNoPackageJson || global) {
      printable = path
    } else {
      printable += `${long ? '\n' : ' '}${path}`
    }
  }

  // TODO there is a LOT of overlap with lib/utils/explain-dep.js here

  const highlightDepName = args.length && node[_filteredBy]
  const missingColor = isOptional(node)
    ? chalk.yellow
    : chalk.red
  const missingMsg = `UNMET ${isOptional(node) ? 'OPTIONAL ' : ''}DEPENDENCY`
  const targetLocation = node.root
    ? relative(node.root.realpath, node.realpath)
    : node.targetLocation
  const invalid = node[_invalid]
    ? `invalid: ${node[_invalid]}`
    : ''
  const label =
    (
      node[_missing]
        ? missingColor(missingMsg) + ' '
        : ''
    ) +
    `${highlightDepName ? chalk.yellow(printable) : printable}` +
    (
      node[_dedupe]
        ? ' ' + chalk.dim('deduped')
        : ''
    ) +
    (
      invalid
        ? ' ' + chalk.red(invalid)
        : ''
    ) +
    (
      isExtraneous(node, { global })
        ? ' ' + chalk.red('extraneous')
        : ''
    ) +
    (
      node.overridden
        ? ' ' + chalk.dim('overridden')
        : ''
    ) +
    (isGitNode(node) ? ` (${node.resolved})` : '') +
    (node.isLink ? ` -> ${relativePrefix}${targetLocation}` : '') +
    (long ? `\n${node.package.description || ''}` : '')

  return augmentItemWithIncludeMetadata(node, { label, nodes: [] })
}

const getJsonOutputItem = (node, { global, long }) => {
  const item = {}

  if (node.version) {
    item.version = node.version
  }

  if (node.resolved) {
    item.resolved = node.resolved
  }

  // if the node is the project root, do not add the overridden flag. the project root can't be
  // overridden anyway, and if we add the flag it causes undesirable behavior when `npm ls --json`
  // is ran in an empty directory since we end up printing an object with only an overridden prop
  if (!node.isProjectRoot) {
    item.overridden = node.overridden
  }

  item[_name] = node.name

  // special formatting for top-level package name
  const hasPackageJson =
    node && node.package && Object.keys(node.package).length
  if (node.isRoot && hasPackageJson) {
    item.name = node.package.name || node.name
  }

  if (long && !node[_missing]) {
    item.name = item[_name]
    const { dependencies, ...packageInfo } = node.package
    Object.assign(item, packageInfo)
    item.extraneous = false
    item.path = node.path
    item._dependencies = {
      ...node.package.dependencies,
      ...node.package.optionalDependencies,
    }
    item.devDependencies = node.package.devDependencies || {}
    item.peerDependencies = node.package.peerDependencies || {}
  }

  // augment json output items with extra metadata
  if (isExtraneous(node, { global })) {
    item.extraneous = true
  }

  if (node[_invalid]) {
    item.invalid = node[_invalid]
  }

  if (node[_missing] && !isOptional(node)) {
    item.required = node[_required]
    item.missing = true
  }
  if (node[_include] && node[_problems] && node[_problems].size) {
    item.problems = [...node[_problems]]
  }

  return augmentItemWithIncludeMetadata(node, item)
}

const filterByEdgesTypes = ({ link, omit }) => (edge) => {
  for (const omitType of omit) {
    if (edge[omitType]) {
      return false
    }
  }
  return link ? edge.to && edge.to.isLink : true
}

const appendExtraneousChildren = ({ node, seenPaths }) =>
  // extraneous children are not represented
  // in edges out, so here we add them to the list:
  [...node.children.values()]
    .filter(i => !seenPaths.has(i.path) && i.extraneous)

const mapEdgesToNodes = ({ seenPaths }) => (edge) => {
  let node = edge.to

  // if the edge is linking to a missing node, we go ahead
  // and create a new obj that will represent the missing node
  if (edge.missing || (edge.optional && !node)) {
    const { name, spec } = edge
    const pkgid = `${name}@${spec}`
    node = { name, pkgid, [_missing]: edge.from.pkgid }
  }

  // keeps track of a set of seen paths to avoid the edge case in which a tree
  // item would appear twice given that it's a children of an extraneous item,
  // so it's marked extraneous but it will ALSO show up in edgesOuts of
  // its parent so it ends up as two diff nodes if we don't track it
  if (node.path) {
    seenPaths.add(node.path)
  }

  node[_required] = edge.spec || '*'
  node[_type] = edge.type

  if (edge.invalid) {
    const spec = JSON.stringify(node[_required])
    const from = edge.from.location || 'the root project'
    node[_invalid] = (node[_invalid] ? node[_invalid] + ', ' : '') +
      (`${spec} from ${from}`)
  }

  return node
}

const filterByPositionalArgs = (args, { node }) =>
  args.length > 0 ? args.some(
    (spec) => (node.satisfies && node.satisfies(spec))
  ) : true

const augmentNodesWithMetadata = ({
  args,
  currentDepth,
  nodeResult,
  seenNodes,
}) => (node) => {
  // if the original edge was a deduped dep, treeverse will fail to
  // revisit that node in tree traversal logic, so we make it so that
  // we have a diff obj for deduped nodes:
  if (seenNodes.has(node.path)) {
    const { realpath, root } = node
    const targetLocation = root ? relative(root.realpath, realpath)
      : node.targetLocation
    node = {
      name: node.name,
      version: node.version,
      pkgid: node.pkgid,
      package: node.package,
      path: node.path,
      isLink: node.isLink,
      realpath: node.realpath,
      targetLocation,
      [_type]: node[_type],
      [_invalid]: node[_invalid],
      [_missing]: node[_missing],
      // if it's missing, it's not deduped, it's just missing
      [_dedupe]: !node[_missing],
    }
  } else {
    // keeps track of already seen nodes in order to check for dedupes
    seenNodes.set(node.path, node)
  }

  // _parent is going to be a ref to a treeverse-visited node (returned from
  // getHumanOutputItem, getJsonOutputItem, etc) so that we have an easy
  // shortcut to place new nodes in their right place during tree traversal
  node[_parent] = nodeResult
  // _include is the property that allow us to filter based on position args
  // e.g: `npm ls foo`, `npm ls simple-output@2`
  // _filteredBy is used to apply extra color info to the item that
  // was used in args in order to filter
  node[_filteredBy] = node[_include] =
    filterByPositionalArgs(args, { node: seenNodes.get(node.path) })
  // _depth keeps track of how many levels deep tree traversal currently is
  // so that we can `npm ls --depth=1`
  node[_depth] = currentDepth + 1

  return node
}

const sortAlphabetically = ({ pkgid: a }, { pkgid: b }) => localeCompare(a, b)

const humanOutput = ({ chalk, result, seenItems, unicode }) => {
  // we need to traverse the entire tree in order to determine which items
  // should be included (since a nested transitive included dep will make it
  // so that all its ancestors should be displayed)
  // here is where we put items in their expected place for archy output
  for (const item of seenItems) {
    if (item[_include] && item[_parent]) {
      item[_parent].nodes.push(item)
    }
  }

  if (!result.nodes.length) {
    result.nodes = ['(empty)']
  }

  const archyOutput = archy(result, '', { unicode })
  return chalk.reset(archyOutput)
}

const jsonOutput = ({ path, problems, result, rootError, seenItems }) => {
  if (problems.size) {
    result.problems = [...problems]
  }

  if (rootError) {
    result.problems = [
      ...(result.problems || []),
      ...[`error in ${path}: Failed to parse root package.json`],
    ]
    result.invalid = true
  }

  // we need to traverse the entire tree in order to determine which items
  // should be included (since a nested transitive included dep will make it
  // so that all its ancestors should be displayed)
  // here is where we put items in their expected place for json output
  for (const item of seenItems) {
    // append current item to its parent item.dependencies obj in order
    // to provide a json object structure that represents the installed tree
    if (item[_include] && item[_parent]) {
      if (!item[_parent].dependencies) {
        item[_parent].dependencies = {}
      }

      item[_parent].dependencies[item[_name]] = item
    }
  }

  return JSON.stringify(result, null, 2)
}

const parseableOutput = ({ global, long, seenNodes }) => {
  let out = ''
  for (const node of seenNodes.values()) {
    if (node.path && node[_include]) {
      out += node.path
      if (long) {
        out += `:${node.pkgid}`
        out += node.path !== node.realpath ? `:${node.realpath}` : ''
        out += isExtraneous(node, { global }) ? ':EXTRANEOUS' : ''
        out += node[_invalid] ? ':INVALID' : ''
        out += node.overridden ? ':OVERRIDDEN' : ''
      }
      out += '\n'
    }
  }
  return out.trim()
}