import Release from "./Release"
import { eq, SemVer } from "semver"

export default class Changelog {
  flag?: string
  title: string
  description: string
  head = "HEAD"
  footer?: string
  url?: string
  releases: Release[] = []
  tagNameBuilder?: (release: Release) => string
  format: "compact" | "markdownlint" = "compact"

  constructor(title: string, description = "") {
    this.title = title
    this.description = description
  }

  addRelease(release: Release) {
    this.releases.push(release)
    this.sortReleases()
    release.changelog = this

    return this
  }

  findRelease(version?: SemVer | string) {
    if (!version) {
      return this.releases.find((release) => !release.version)
    }
    return this.releases.find((release) => release.version && eq(release.version, version))
  }

  sortReleases() {
    this.releases.sort((a, b) => a.compare(b))
  }

  tagName(release: Release) {
    if (this.tagNameBuilder) {
      return this.tagNameBuilder(release)
    }

    return `v${release.version}`
  }

  toString() {
    const t: string[] = []

    if (this.flag) {
      t.push(`<!-- ${this.flag} -->`)
      t.push("")
    }

    t.push(`# ${this.title}`)

    if (this.format === "markdownlint") {
      t.push("")
    }

    const links: string[] = []
    const compareLinks: string[] = []

    const description =
      this.description.trim() ||
      `All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](http://keepachangelog.com/)
and this project adheres to [Semantic Versioning](http://semver.org/).`

    if (description) {
      t.push(description)
    }

    this.releases.forEach((release) => {
      t.push("")
      t.push(release.toString(this))

      release.getLinks(this).forEach((link) => {
        if (!links.includes(link)) {
          links.push(link)
        }
      })

      const compareLink = release.getCompareLink(this)

      if (compareLink) {
        compareLinks.push(compareLink)
      }
    })

    if (links.length) {
      t.push("")
      links.sort(compare)
      links.forEach((link) => t.push(link))
    }

    if (compareLinks.length) {
      t.push("")

      compareLinks.forEach((link) => t.push(link))
    }

    t.push("")

    if (this.footer) {
      t.push("---")
      t.push("")
      t.push(this.footer)
      t.push("")
    }

    return t.join("\n")
  }
}

function compare(a: string, b: string) {
  if (a === b) {
    return 0
  }
  const reg = /^\[#(\d+)\]:/
  const aNumber = a.match(reg)
  const bNumber = b.match(reg)

  if (aNumber && bNumber) {
    return parseInt(aNumber[1]) - parseInt(bNumber[1])
  }

  return a < b ? -1 : 1
}