var url = require("url")

var log = require("npmlog")
  , npa = require("npm-package-arg")

module.exports = mapToRegistry

function mapToRegistry(name, config, cb) {
  log.silly("mapToRegistry", "name", name)
  var registry

  // the name itself takes precedence
  var data = npa(name)
  if (data.scope) {
    // the name is definitely scoped, so escape now
    name = name.replace("/", "%2f")

    log.silly("mapToRegistry", "scope (from package name)", data.scope)

    registry = config.get(data.scope + ":registry")
    if (!registry) {
      log.verbose("mapToRegistry", "no registry URL found in name for scope", data.scope)
    }
  }

  // ...then --scope=@scope or --scope=scope
  var scope = config.get("scope")
  if (!registry && scope) {
    // I'm an enabler, sorry
    if (scope.charAt(0) !== "@") scope = "@" + scope

    log.silly("mapToRegistry", "scope (from config)", scope)

    registry = config.get(scope + ":registry")
    if (!registry) {
      log.verbose("mapToRegistry", "no registry URL found in config for scope", scope)
    }
  }

  // ...and finally use the default registry
  if (!registry) {
    log.silly("mapToRegistry", "using default registry")
    registry = config.get("registry")
  }

  log.silly("mapToRegistry", "registry", registry)

  var auth = config.getCredentialsByURI(registry)

  // normalize registry URL so resolution doesn't drop a piece of registry URL
  var normalized = registry.slice(-1) !== "/" ? registry+"/" : registry
  var uri = url.resolve(normalized, name)
  log.silly("mapToRegistry", "uri", uri)

  cb(null, uri, auth, normalized)
}