#! /usr/bin/env node

const acorn = require('acorn')
const acornWalk = require('acorn-walk')
const fs = require('fs')
const _ = require('lodash')
const glob = require('glob')
const escodegen = require('escodegen')
const print = console.log

const Methods = new Set([
  'get',
  'head',
  'post',
  'put',
  'delete',
  'connect',
  'options',
  'trace',
  'patch',
])

const isMethod = str => {
  return Methods.has(str)
}

// Check if the expression is a call on a router, return data about it, or null
const routerCall = callExpression => {
  const callee = callExpression.callee
  const property = callee.property
  const args = callExpression.arguments
  if (!callee.object || !callee.object.name) {
    return false
  }
  const routerName = callee.object.name
  if (
    // Match known names for the Express routers: app, webRouter, whateverRouter, etc...
    isMethod(property.name) &&
    (routerName === 'app' || routerName.match('^.*[rR]outer$'))
  ) {
    return {
      routerName: routerName,
      method: property.name,
      args: args,
    }
  } else {
    return null
  }
}

const formatMethodCall = expression => {
  return escodegen.generate(expression, { format: { compact: true } })
}

const parseAndPrintRoutesSync = path => {
  const content = fs.readFileSync(path)
  // Walk the AST (Abstract Syntax Tree)
  acornWalk.simple(acorn.parse(content), {
    // We only care about call expression ( like `a.b()` )
    CallExpression(node) {
      const call = routerCall(node)
      if (call) {
        const firstArg = _.first(call.args)
        try {
          print(
            `  ${formatRouterName(call.routerName)}\t .${call.method} \t: ${
              firstArg.value
            } => ${call.args.slice(1).map(formatMethodCall).join(' => ')}`
          )
        } catch (e) {
          print('>> Error')
          print(e)
          print(JSON.stringify(call))
          process.exit(1)
        }
      }
    },
  })
}

const routerNameMapping = {
  privateApiRouter: 'privateApi',
  publicApiRouter: 'publicApi',
}
const formatRouterName = name => {
  return routerNameMapping[name] || name
}

const main = () => {
  // Take an optional filter to apply to file names
  const filter = process.argv[2] || null

  if (filter && (filter === '--help' || filter === 'help')) {
    print('')
    print('  Usage: bin/routes [filter]')
    print('  Examples:')
    print('    bin/routes')
    print('    bin/routes GitBridge')
    print('')
    process.exit(0)
  }

  // Find all routers
  glob('*[rR]outer.js', { matchBase: true }, (err, files) => {
    if (err) {
      console.error(err)
      process.exit(1)
    }
    for (const file of files) {
      if (file.match('^node_modules.*$') || file.match('.*/public/.*')) {
        continue
      }
      // Restrict to the filter (if filter is present)
      if (filter && !file.match(`.*${filter}.*`)) {
        continue
      }
      print(`[${file}]`)
      try {
        parseAndPrintRoutesSync(file)
      } catch (_e) {
        print('>> Error parsing file')
        continue
      }
    }
    process.exit(0)
  })
}

if (require.main === module) {
  main()
}