import { $ } from "bun"

const fallback = "No notable changes"
const pattern = /^v?(\d+\.\d+\.\d+(?:-[0-9A-Za-z.-]+)?)$/

type Release = {
  tagName: string
  isDraft: boolean
  isPrerelease: boolean
}

export function buildNotes(input: { version: string; prerelease: boolean; releases: Release[]; changelog: string }) {
  const target = version(input.version)
  if (!target) throw new Error(`Invalid release version: ${input.version}`)

  const sections = parse(input.changelog)
  const current = sections.find((section) => section.version === target)
  if (!current) return fallback
  if (input.prerelease) return current.body || fallback

  const stable = input.releases
    .flatMap((release) => {
      const value = version(release.tagName)
      if (!value || release.isDraft || release.isPrerelease || compare(value, target) >= 0) return []
      return [value]
    })
    .sort((a, b) => compare(b, a))[0]
  const versions = new Set([
    target,
    ...input.releases.flatMap((release) => {
      const value = version(release.tagName)
      if (!value || release.isDraft || !release.isPrerelease || compare(value, target) >= 0) return []
      if (stable && compare(value, stable) <= 0) return []
      return [value]
    }),
  ])
  const notes = sections
    .filter((section) => versions.has(section.version) && section.body)
    .map((section) => `## ${section.version}\n\n${section.body}`)
  return notes.join("\n\n") || fallback
}

export async function publishNotes(input: { version: string; prerelease: boolean; repo?: string; temp?: string }) {
  const repo = input.repo ? ["--repo", input.repo] : []
  const releases: Release[] = await $`gh release list --limit 1000 --json tagName,isDraft,isPrerelease ${repo}`.json()
  const changelog = await Bun.file(new URL("../../packages/kilo-vscode/CHANGELOG.md", import.meta.url)).text()
  const body = buildNotes({ ...input, releases, changelog })
  const notes = `${input.temp ?? "/tmp"}/release-notes.txt`
  const target = input.version.startsWith("v") ? input.version : `v${input.version}`
  const flags = input.prerelease ? ["--draft=false", "--prerelease"] : ["--draft=false"]
  await Bun.write(notes, body)
  flags.push("--title", `${target} (${input.prerelease ? "pre-release" : "release"})`, "--notes-file", notes)
  await $`gh release edit ${target} ${flags} ${repo}`
}

function parse(input: string) {
  const matches = Array.from(input.matchAll(/^##\s+(.+)$/gm))
  return matches.flatMap((match, index) => {
    const value = version(match[1] ?? "")
    if (!value) return []
    const start = (match.index ?? 0) + match[0].length
    const end = matches[index + 1]?.index ?? input.length
    return [{ version: value, body: input.slice(start, end).trim() }]
  })
}

function version(input: string) {
  return input.trim().match(pattern)?.[1]
}

function compare(a: string, b: string) {
  return Bun.semver.order(a, b)
}