const Liquid = require('liquid')
const semver = require('semver')
const path = require('path')
const engine = new Liquid.Engine()
engine.registerFileSystem(
  new Liquid.LocalFileSystem(path.join(process.cwd(), 'includes'))
)

// GHE versions are not valid SemVer, but can be coerced...
// https://github.com/npm/node-semver#coercion

Liquid.Condition.operators.ver_gt = (cond, left, right) => {
  if (!matchesVersionString(left)) return false
  if (!matchesVersionString(right)) return false

  const [leftPlan, leftRelease] = splitVersion(left)
  const [rightPlan, rightRelease] = splitVersion(right)

  if (leftPlan !== rightPlan) return false

  return semver.gt(semver.coerce(leftRelease), semver.coerce(rightRelease))
}

Liquid.Condition.operators.ver_lt = (cond, left, right) => {
  if (!matchesVersionString(left)) return false
  if (!matchesVersionString(right)) return false

  const [leftPlan, leftRelease] = splitVersion(left)
  const [rightPlan, rightRelease] = splitVersion(right)

  if (leftPlan !== rightPlan) return false

  return semver.lt(semver.coerce(leftRelease), semver.coerce(rightRelease))
}

module.exports = engine

function matchesVersionString (input) {
  return input && input.match(/^(?:[a-z](?:[a-z-]*[a-z])?@)?\d+(?:\.\d+)*/)
}
// Support new version formats where version = plan@release
// e.g., enterprise-server@2.21, where enterprise-server is the plan and 2.21 is the release
// e.g., free-pro-team@latest, where free-pro-team is the plan and latest is the release
// in addition to legacy formats where the version passed is simply 2.21
function splitVersion (version) {
  // The default plan when working with versions is "enterprise-server".
  // Default to that value here to support backward compatibility from before
  // plans were explicitly included.
  let plan = 'enterprise-server'
  let release

  const lastIndex = version.lastIndexOf('@')
  if (lastIndex === -1) {
    release = version
  } else {
    plan = version.slice(0, lastIndex)
    release = version.slice(lastIndex + 1)
  }

  return [plan, release]
}