import { Octokit } from '@octokit/rest'
import { createHash } from 'crypto'
import type { RemoteFile } from './types'

// ---------------------------------------------------------------------------
// Octokit helpers
// ---------------------------------------------------------------------------

export function getOctokit(): Octokit {
  const token = process.env.GITHUB_TOKEN
  if (!token) throw new Error('GITHUB_TOKEN non configure')
  return new Octokit({ auth: token })
}

export function parseRepoUrl(): { owner: string; repo: string } {
  const url = process.env.GIT_REPO_URL
  if (!url) throw new Error('GIT_REPO_URL non configure')

  const httpsMatch = url.match(/github\.com\/([^/]+)\/([^/.]+)/)
  const sshMatch = url.match(/github\.com:([^/]+)\/([^/.]+)/)
  const shortMatch = url.match(/^([^/]+)\/([^/]+)$/)

  const match = httpsMatch || sshMatch || shortMatch
  if (!match) throw new Error(`Format GIT_REPO_URL invalide: "${url}"`)

  return { owner: match[1], repo: match[2] }
}

/** Compute the SHA that Git would assign to a blob with this content */
export function computeGitBlobSha(content: Buffer): string {
  const header = `blob ${content.length}\0`
  const store = Buffer.concat([Buffer.from(header), content])
  return createHash('sha1').update(store).digest('hex')
}

// ---------------------------------------------------------------------------
// Read remote folder contents (with SHA per file)
// ---------------------------------------------------------------------------

export async function getRemoteFolder(
  folderPath: string,
): Promise<{ exists: boolean; files: RemoteFile[] }> {
  const octokit = getOctokit()
  const { owner, repo } = parseRepoUrl()
  const branch = process.env.GIT_BRANCH ?? 'main'

  try {
    const { data } = await octokit.repos.getContent({
      owner,
      repo,
      path: folderPath,
      ref: branch,
    })

    if (Array.isArray(data)) {
      return {
        exists: true,
        files: data.map((f) => ({ name: f.name, sha: f.sha })),
      }
    }

    return { exists: false, files: [] }
  } catch (err: unknown) {
    const status = (err as { status?: number })?.status
    if (status === 404) {
      return { exists: false, files: [] }
    }
    throw err
  }
}

// ---------------------------------------------------------------------------
// Push all files in a single commit (with optional deletions)
// ---------------------------------------------------------------------------

export async function pushAllToGitHub(
  files: { path: string; contentBase64: string }[],
  deletePaths: string[],
  commitMessage: string,
): Promise<{ commitUrl: string }> {
  const octokit = getOctokit()
  const { owner, repo } = parseRepoUrl()
  const branch = process.env.GIT_BRANCH ?? 'main'

  // 1. Get latest commit on branch
  const { data: ref } = await octokit.git.getRef({
    owner,
    repo,
    ref: `heads/${branch}`,
  })
  const latestCommitSha = ref.object.sha

  // 2. Get that commit's tree
  const { data: commit } = await octokit.git.getCommit({
    owner,
    repo,
    commit_sha: latestCommitSha,
  })

  // 3. Create all blobs in parallel
  const blobResults = await Promise.all(
    files.map((f) =>
      octokit.git.createBlob({
        owner,
        repo,
        content: f.contentBase64,
        encoding: 'base64',
      }),
    ),
  )

  // 4. Build tree entries: new/changed files + deletions
  const newFilePaths = new Set(files.map((f) => f.path))
  const deleteEntries = deletePaths
    .filter((p) => !newFilePaths.has(p))
    .map((p) => ({
      path: p,
      mode: '100644' as const,
      type: 'blob' as const,
      sha: null,
    }))

  const { data: newTree } = await octokit.git.createTree({
    owner,
    repo,
    base_tree: commit.tree.sha,
    tree: [
      ...files.map((f, i) => ({
        path: f.path,
        mode: '100644' as const,
        type: 'blob' as const,
        sha: blobResults[i].data.sha,
      })),
      ...deleteEntries,
    ],
  })

  // 5. Create a single commit
  const { data: newCommit } = await octokit.git.createCommit({
    owner,
    repo,
    message: commitMessage,
    tree: newTree.sha,
    parents: [latestCommitSha],
  })

  // 6. Update branch ref
  await octokit.git.updateRef({
    owner,
    repo,
    ref: `heads/${branch}`,
    sha: newCommit.sha,
  })

  return { commitUrl: newCommit.html_url }
}