import { Base64 } from 'js-base64';
import semaphore, { Semaphore } from 'semaphore';
import { initial, last, partial, result, trimStart, trim } from 'lodash';
import {
  getAllResponses,
  APIError,
  EditorialWorkflowError,
  localForage,
  basename,
  AssetProxy,
  Entry as LibEntry,
  PersistOptions,
  readFile,
  CMS_BRANCH_PREFIX,
  generateContentKey,
  DEFAULT_PR_BODY,
  MERGE_COMMIT_MESSAGE,
  PreviewState,
  FetchError,
  parseContentKey,
  branchFromContentKey,
  isCMSLabel,
  labelToStatus,
  statusToLabel,
  contentKeyFromBranch,
} from 'netlify-cms-lib-util';
import { Octokit } from '@octokit/rest';

type GitHubUser = Octokit.UsersGetAuthenticatedResponse;
type GitCreateTreeParamsTree = Octokit.GitCreateTreeParamsTree;
type GitHubCompareCommit = Octokit.ReposCompareCommitsResponseCommitsItem;
type GitHubAuthor = Octokit.GitCreateCommitResponseAuthor;
type GitHubCommitter = Octokit.GitCreateCommitResponseCommitter;
type GitHubPull = Octokit.PullsListResponseItem;

export const API_NAME = 'GitHub';

export const MOCK_PULL_REQUEST = -1;

export interface Config {
  apiRoot?: string;
  token?: string;
  branch?: string;
  useOpenAuthoring?: boolean;
  repo?: string;
  originRepo?: string;
  squashMerges: boolean;
  initialWorkflowStatus: string;
}

interface TreeFile {
  type: 'blob' | 'tree';
  sha: string;
  path: string;
  raw?: string;
}

export interface Entry extends LibEntry {
  sha?: string;
}

type Override<T, U> = Pick<T, Exclude<keyof T, keyof U>> & U;

type TreeEntry = Override<GitCreateTreeParamsTree, { sha: string | null }>;

type GitHubCompareCommits = GitHubCompareCommit[];

type GitHubCompareFile = Octokit.ReposCompareCommitsResponseFilesItem & {
  previous_filename?: string;
};

type GitHubCompareFiles = GitHubCompareFile[];

enum GitHubCommitStatusState {
  Error = 'error',
  Failure = 'failure',
  Pending = 'pending',
  Success = 'success',
}

export enum PullRequestState {
  Open = 'open',
  Closed = 'closed',
  All = 'all',
}

type GitHubCommitStatus = Octokit.ReposListStatusesForRefResponseItem & {
  state: GitHubCommitStatusState;
};

interface MetaDataObjects {
  entry: { path: string; sha: string };
  files: MediaFile[];
}

export interface Metadata {
  type: string;
  objects: MetaDataObjects;
  branch: string;
  status: string;
  pr?: {
    number: number;
    head: string | { sha: string };
  };
  collection: string;
  commitMessage: string;
  version?: string;
  user: string;
  title?: string;
  description?: string;
  timeStamp: string;
}

export interface BlobArgs {
  sha: string;
  repoURL: string;
  parseText: boolean;
}

type Param = string | number | undefined;

type Options = RequestInit & { params?: Record<string, Param | Record<string, Param> | string[]> };

type MediaFile = {
  sha: string;
  path: string;
};

const withCmsLabel = (pr: GitHubPull) => pr.labels.some(l => isCMSLabel(l.name));
const withoutCmsLabel = (pr: GitHubPull) => pr.labels.every(l => !isCMSLabel(l.name));

const getTreeFiles = (files: GitHubCompareFiles) => {
  const treeFiles = files.reduce((arr, file) => {
    if (file.status === 'removed') {
      // delete the file
      arr.push({ sha: null, path: file.filename });
    } else if (file.status === 'renamed') {
      // delete the previous file
      arr.push({ sha: null, path: file.previous_filename as string });
      // add the renamed file
      arr.push({ sha: file.sha, path: file.filename });
    } else {
      // add the  file
      arr.push({ sha: file.sha, path: file.filename });
    }
    return arr;
  }, [] as { sha: string | null; path: string }[]);

  return treeFiles;
};

export default class API {
  apiRoot: string;
  token: string;
  branch: string;
  useOpenAuthoring?: boolean;
  repo: string;
  originRepo: string;
  repoOwner: string;
  repoName: string;
  originRepoOwner: string;
  originRepoName: string;
  repoURL: string;
  originRepoURL: string;
  mergeMethod: string;
  initialWorkflowStatus: string;

  _userPromise?: Promise<GitHubUser>;
  _metadataSemaphore?: Semaphore;

  commitAuthor?: {};

  constructor(config: Config) {
    this.apiRoot = config.apiRoot || 'https://api.github.com';
    this.token = config.token || '';
    this.branch = config.branch || 'master';
    this.useOpenAuthoring = config.useOpenAuthoring;
    this.repo = config.repo || '';
    this.originRepo = config.originRepo || this.repo;
    this.repoURL = `/repos/${this.repo}`;
    // when not in 'useOpenAuthoring' mode originRepoURL === repoURL
    this.originRepoURL = `/repos/${this.originRepo}`;

    const [repoParts, originRepoParts] = [this.repo.split('/'), this.originRepo.split('/')];
    this.repoOwner = repoParts[0];
    this.repoName = repoParts[1];

    this.originRepoOwner = originRepoParts[0];
    this.originRepoName = originRepoParts[1];

    this.mergeMethod = config.squashMerges ? 'squash' : 'merge';
    this.initialWorkflowStatus = config.initialWorkflowStatus;
  }

  static DEFAULT_COMMIT_MESSAGE = 'Automatically generated by Netlify CMS';

  user(): Promise<{ name: string; login: string }> {
    if (!this._userPromise) {
      this._userPromise = this.request('/user') as Promise<GitHubUser>;
    }
    return this._userPromise;
  }

  async hasWriteAccess() {
    try {
      const result: Octokit.ReposGetResponse = await this.request(this.repoURL);
      return result.permissions.push;
    } catch (error) {
      console.error('Problem fetching repo data from GitHub');
      throw error;
    }
  }

  reset() {
    // no op
  }

  requestHeaders(headers = {}) {
    const baseHeader: Record<string, string> = {
      'Content-Type': 'application/json; charset=utf-8',
      ...headers,
    };

    if (this.token) {
      baseHeader.Authorization = `token ${this.token}`;
      return Promise.resolve(baseHeader);
    }

    return Promise.resolve(baseHeader);
  }

  parseJsonResponse(response: Response) {
    return response.json().then(json => {
      if (!response.ok) {
        return Promise.reject(json);
      }

      return json;
    });
  }

  urlFor(path: string, options: Options) {
    const cacheBuster = new Date().getTime();
    const params = [`ts=${cacheBuster}`];
    if (options.params) {
      for (const key in options.params) {
        params.push(`${key}=${encodeURIComponent(options.params[key] as string)}`);
      }
    }
    if (params.length) {
      path += `?${params.join('&')}`;
    }
    return this.apiRoot + path;
  }

  parseResponse(response: Response) {
    const contentType = response.headers.get('Content-Type');
    if (contentType && contentType.match(/json/)) {
      return this.parseJsonResponse(response);
    }
    const textPromise = response.text().then(text => {
      if (!response.ok) {
        return Promise.reject(text);
      }
      return text;
    });
    return textPromise;
  }

  handleRequestError(error: FetchError, responseStatus: number) {
    throw new APIError(error.message, responseStatus, API_NAME);
  }

  async request(
    path: string,
    options: Options = {},
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    parser = (response: Response) => this.parseResponse(response),
  ) {
    const headers = await this.requestHeaders(options.headers || {});
    const url = this.urlFor(path, options);
    let responseStatus: number;
    return fetch(url, { ...options, headers })
      .then(response => {
        responseStatus = response.status;
        return parser(response);
      })
      .catch(error => this.handleRequestError(error, responseStatus));
  }

  nextUrlProcessor() {
    return (url: string) => url;
  }

  async requestAllPages<T>(url: string, options: Options = {}) {
    const headers = await this.requestHeaders(options.headers || {});
    const processedURL = this.urlFor(url, options);
    const allResponses = await getAllResponses(
      processedURL,
      { ...options, headers },
      'next',
      this.nextUrlProcessor(),
    );
    const pages: T[][] = await Promise.all(
      allResponses.map((res: Response) => this.parseResponse(res)),
    );
    return ([] as T[]).concat(...pages);
  }

  generateContentKey(collectionName: string, slug: string) {
    const contentKey = generateContentKey(collectionName, slug);
    if (!this.useOpenAuthoring) {
      return contentKey;
    }

    return `${this.repo}/${contentKey}`;
  }

  parseContentKey(contentKey: string) {
    if (!this.useOpenAuthoring) {
      return parseContentKey(contentKey);
    }

    return parseContentKey(contentKey.substring(this.repo.length + 1));
  }

  checkMetadataRef() {
    return this.request(`${this.repoURL}/git/refs/meta/_netlify_cms`, {
      cache: 'no-store',
    })
      .then(response => response.object)
      .catch(() => {
        // Meta ref doesn't exist
        const readme = {
          raw:
            '# Netlify CMS\n\nThis tree is used by the Netlify CMS to store metadata information for specific files and branches.',
        };

        return this.uploadBlob(readme)
          .then(item =>
            this.request(`${this.repoURL}/git/trees`, {
              method: 'POST',
              body: JSON.stringify({
                tree: [{ path: 'README.md', mode: '100644', type: 'blob', sha: item.sha }],
              }),
            }),
          )
          .then(tree => this.commit('First Commit', tree))
          .then(response => this.createRef('meta', '_netlify_cms', response.sha))
          .then(response => response.object);
      });
  }

  async storeMetadata(key: string, data: Metadata) {
    // semaphore ensures metadata updates are always ordered, even if
    // calls to storeMetadata are not. concurrent metadata updates
    // will result in the metadata branch being unable to update.
    if (!this._metadataSemaphore) {
      this._metadataSemaphore = semaphore(1);
    }
    return new Promise((resolve, reject) =>
      this._metadataSemaphore?.take(async () => {
        try {
          const branchData = await this.checkMetadataRef();
          const file = { path: `${key}.json`, raw: JSON.stringify(data) };

          await this.uploadBlob(file);
          const changeTree = await this.updateTree(branchData.sha, [file as TreeFile]);
          const { sha } = await this.commit(`Updating “${key}” metadata`, changeTree);
          await this.patchRef('meta', '_netlify_cms', sha);
          localForage.setItem(`gh.meta.${key}`, {
            expires: Date.now() + 300000, // In 5 minutes
            data,
          });
          this._metadataSemaphore?.leave();
          resolve();
        } catch (err) {
          reject(err);
        }
      }),
    );
  }

  deleteMetadata(key: string) {
    if (!this._metadataSemaphore) {
      this._metadataSemaphore = semaphore(1);
    }
    return new Promise(resolve =>
      this._metadataSemaphore?.take(async () => {
        try {
          const branchData = await this.checkMetadataRef();
          const file = { path: `${key}.json`, sha: null };

          const changeTree = await this.updateTree(branchData.sha, [file]);
          const { sha } = await this.commit(`Deleting “${key}” metadata`, changeTree);
          await this.patchRef('meta', '_netlify_cms', sha);
          this._metadataSemaphore?.leave();
          resolve();
        } catch (err) {
          this._metadataSemaphore?.leave();
          resolve();
        }
      }),
    );
  }

  retrieveMetadataOld(key: string): Promise<Metadata> {
    const cache = localForage.getItem<{ data: Metadata; expires: number }>(`gh.meta.${key}`);
    return cache.then(cached => {
      if (cached && cached.expires > Date.now()) {
        return cached.data as Metadata;
      }
      console.log(
        '%c Checking for MetaData files',
        'line-height: 30px;text-align: center;font-weight: bold',
      );

      const metadataRequestOptions = {
        params: { ref: 'refs/meta/_netlify_cms' },
        headers: { Accept: 'application/vnd.github.v3.raw' },
        cache: 'no-store' as RequestCache,
      };

      const errorHandler = (err: Error) => {
        if (err.message === 'Not Found') {
          console.log(
            '%c %s does not have metadata',
            'line-height: 30px;text-align: center;font-weight: bold',
            key,
          );
        }
        throw err;
      };

      if (!this.useOpenAuthoring) {
        return this.request(`${this.repoURL}/contents/${key}.json`, metadataRequestOptions)
          .then((response: string) => JSON.parse(response))
          .catch(errorHandler);
      }

      const [user, repo] = key.split('/');
      return this.request(`/repos/${user}/${repo}/contents/${key}.json`, metadataRequestOptions)
        .then((response: string) => JSON.parse(response))
        .catch(errorHandler);
    });
  }

  async getPullRequests(
    head: string | undefined,
    state: PullRequestState,
    predicate: (pr: GitHubPull) => boolean,
  ) {
    const pullRequests: Octokit.PullsListResponse = await this.requestAllPages(
      `${this.originRepoURL}/pulls`,
      {
        params: {
          ...(head ? { head: await this.getHeadReference(head) } : {}),
          base: this.branch,
          state,
          // eslint-disable-next-line @typescript-eslint/camelcase
          per_page: 100,
        },
      },
    );

    return pullRequests.filter(predicate);
  }

  async getOpenAuthoringPullRequest(branch: string, pullRequests: GitHubPull[]) {
    // we can't use labels when using open authoring
    // since the contributor doesn't have access to set labels
    // a branch without a pr (or a closed pr) means a 'draft' entry
    // a branch with an opened pr means a 'pending_review' entry
    const data = await this.getBranch(branch);
    // since we get all (open and closed) pull requests by branch name, make sure to filter by head sha
    const pullRequest = pullRequests.filter(pr => pr.head.sha === data.commit.sha)[0];
    // if no pull request is found for the branch we return a mocked one
    if (!pullRequest) {
      try {
        return {
          head: { sha: data.commit.sha },
          number: MOCK_PULL_REQUEST,
          labels: [{ name: statusToLabel(this.initialWorkflowStatus) }],
          state: PullRequestState.Open,
        } as GitHubPull;
      } catch (e) {
        throw new EditorialWorkflowError('content is not under editorial workflow', true);
      }
    } else {
      pullRequest.labels = pullRequest.labels.filter(l => !isCMSLabel(l.name));
      const cmsLabel =
        pullRequest.state === PullRequestState.Closed
          ? { name: statusToLabel(this.initialWorkflowStatus) }
          : { name: statusToLabel('pending_review') };

      pullRequest.labels.push(cmsLabel as Octokit.PullsGetResponseLabelsItem);
      return pullRequest;
    }
  }

  async getBranchPullRequest(branch: string) {
    if (this.useOpenAuthoring) {
      const pullRequests = await this.getPullRequests(branch, PullRequestState.All, () => true);
      return this.getOpenAuthoringPullRequest(branch, pullRequests);
    } else {
      const pullRequests = await this.getPullRequests(branch, PullRequestState.Open, withCmsLabel);
      if (pullRequests.length <= 0) {
        throw new EditorialWorkflowError('content is not under editorial workflow', true);
      }
      return pullRequests[0];
    }
  }

  async retrieveMetadata(contentKey: string) {
    const { collection, slug } = this.parseContentKey(contentKey);
    const branch = branchFromContentKey(contentKey);
    const pullRequest = await this.getBranchPullRequest(branch);
    const { files: diffs } = await this.getDifferences(
      this.branch,
      pullRequest.head.sha,
      this.repoURL,
    );
    // media files don't have a patch attribute, except svg files
    const { path, newFile } = diffs
      .filter(d => d.patch && !d.filename.endsWith('.svg'))
      .map(f => ({ path: f.filename, newFile: f.status === 'added' }))[0];

    const mediaFiles = diffs
      .filter(d => d.filename !== path)
      .map(({ filename: path, sha: id }) => ({
        path,
        id,
      }));
    const label = pullRequest.labels.find(l => isCMSLabel(l.name)) as { name: string };
    const status = labelToStatus(label.name);
    return { branch, collection, slug, path, status, newFile, mediaFiles, pullRequest };
  }

  async readFile(
    path: string,
    sha?: string | null,
    {
      branch = this.branch,
      repoURL = this.repoURL,
      parseText = true,
    }: {
      branch?: string;
      repoURL?: string;
      parseText?: boolean;
    } = {},
  ) {
    if (!sha) {
      sha = await this.getFileSha(path, { repoURL, branch });
    }
    const fetchContent = () => this.fetchBlobContent({ sha: sha as string, repoURL, parseText });
    const content = await readFile(sha, fetchContent, localForage, parseText);
    return content;
  }

  async fetchBlobContent({ sha, repoURL, parseText }: BlobArgs) {
    const result: Octokit.GitGetBlobResponse = await this.request(`${repoURL}/git/blobs/${sha}`);

    if (parseText) {
      // treat content as a utf-8 string
      const content = Base64.decode(result.content);
      return content;
    } else {
      // treat content as binary and convert to blob
      const content = Base64.atob(result.content);
      const byteArray = new Uint8Array(content.length);
      for (let i = 0; i < content.length; i++) {
        byteArray[i] = content.charCodeAt(i);
      }
      const blob = new Blob([byteArray]);
      return blob;
    }
  }

  async listFiles(
    path: string,
    { repoURL = this.repoURL, branch = this.branch, depth = 1 } = {},
  ): Promise<{ type: string; id: string; name: string; path: string; size: number }[]> {
    const folder = trim(path, '/');
    try {
      const result: Octokit.GitGetTreeResponse = await this.request(
        `${repoURL}/git/trees/${branch}:${folder}`,
        {
          // GitHub API supports recursive=1 for getting the entire recursive tree
          // or omitting it to get the non-recursive tree
          params: depth > 1 ? { recursive: 1 } : {},
        },
      );
      return (
        result.tree
          // filter only files and up to the required depth
          .filter(file => file.type === 'blob' && file.path.split('/').length <= depth)
          .map(file => ({
            type: file.type,
            id: file.sha,
            name: basename(file.path),
            path: `${folder}/${file.path}`,
            size: file.size!,
          }))
      );
    } catch (err) {
      if (err && err.status === 404) {
        console.log('This 404 was expected and handled appropriately.');
        return [];
      } else {
        throw err;
      }
    }
  }

  async readUnpublishedBranchFile(contentKey: string) {
    try {
      const {
        branch,
        collection,
        slug,
        path,
        status,
        newFile,
        mediaFiles,
      } = await this.retrieveMetadata(contentKey);

      const repoURL = this.useOpenAuthoring
        ? `/repos/${contentKey
            .split('/')
            .slice(0, 2)
            .join('/')}`
        : this.repoURL;

      const fileData = (await this.readFile(path, null, { branch, repoURL })) as string;

      return {
        slug,
        metaData: { branch, collection, objects: { entry: { path, mediaFiles } }, status },
        fileData,
        isModification: !newFile,
      };
    } catch (e) {
      throw new EditorialWorkflowError('content is not under editorial workflow', true);
    }
  }

  filterOpenAuthoringBranches = async (branch: string) => {
    const contentKey = contentKeyFromBranch(branch);
    const { pullRequest, collection, slug } = await this.retrieveMetadata(contentKey);
    const { state: currentState, merged_at: mergedAt } = pullRequest;
    if (
      pullRequest.number !== MOCK_PULL_REQUEST &&
      currentState === PullRequestState.Closed &&
      mergedAt
    ) {
      // pr was merged, delete entry
      await this.deleteUnpublishedEntry(collection, slug);
      return { branch, filter: false };
    } else {
      return { branch, filter: true };
    }
  };

  async migrateToVersion1(pullRequest: GitHubPull, metadata: Metadata) {
    // hard code key/branch generation logic to ignore future changes
    const oldContentKey = pullRequest.head.ref.substring(`cms/`.length);
    const newContentKey = `${metadata.collection}/${oldContentKey}`;
    const newBranchName = `cms/${newContentKey}`;

    // create new branch and pull request in new format
    await this.createBranch(newBranchName, pullRequest.head.sha as string);
    const pr = await this.createPR(pullRequest.title, newBranchName);

    // store new metadata
    const newMetadata = {
      ...metadata,
      pr: {
        number: pr.number,
        head: pr.head.sha,
      },
      branch: newBranchName,
      version: '1',
    };
    await this.storeMetadata(newContentKey, newMetadata);

    // remove old data
    await this.closePR(metadata.pr!.number);
    await this.deleteBranch(metadata.branch);
    await this.deleteMetadata(oldContentKey);

    return { metadata: newMetadata, pullRequest: pr };
  }

  async migrateToPullRequestLabels(pullRequest: GitHubPull, metadata: Metadata) {
    await this.setPullRequestStatus(pullRequest, metadata.status);

    const contentKey = pullRequest.head.ref.substring(`cms/`.length);
    await this.deleteMetadata(contentKey);
  }

  async migratePullRequest(pullRequest: GitHubPull) {
    let metadata = await this.retrieveMetadataOld(contentKeyFromBranch(pullRequest.head.ref)).catch(
      () => undefined,
    );

    if (!metadata) {
      return;
    }

    if (!metadata.version) {
      // migrate branch from cms/slug to cms/collection/slug
      ({ metadata, pullRequest } = await this.migrateToVersion1(pullRequest, metadata));
    }

    if (metadata.version === '1') {
      // migrate branch from using orphan ref to store metadata to pull requests label
      await this.migrateToPullRequestLabels(pullRequest, metadata);
    }
  }

  async getCmsBranches() {
    const cmsBranches = await this.requestAllPages<Octokit.GitListMatchingRefsResponseItem>(
      `${this.repoURL}/git/refs/heads/cms`,
    ).catch(() => [] as Octokit.GitListMatchingRefsResponseItem[]);
    return cmsBranches;
  }

  async listUnpublishedBranches() {
    console.log(
      '%c Checking for Unpublished entries',
      'line-height: 30px;text-align: center;font-weight: bold',
    );

    let branches: string[];
    if (this.useOpenAuthoring) {
      // open authoring branches can exist without a pr
      const cmsBranches: Octokit.GitListMatchingRefsResponse = await this.getCmsBranches();
      branches = cmsBranches.map(b => b.ref.substring('refs/heads/'.length));
      // filter irrelevant branches
      const branchesWithFilter = await Promise.all(
        branches.map(b => this.filterOpenAuthoringBranches(b)),
      );
      branches = branchesWithFilter.filter(b => b.filter).map(b => b.branch);
    } else {
      // backwards compatibility code, get relevant pull requests and migrate them
      const pullRequests = await this.getPullRequests(
        undefined,
        PullRequestState.Open,
        withoutCmsLabel,
      );
      for (const pr of pullRequests) {
        await this.migratePullRequest(pr);
      }
      const cmsPullRequests = await this.getPullRequests(
        undefined,
        PullRequestState.Open,
        withCmsLabel,
      );
      branches = cmsPullRequests.map(pr => pr.head.ref);
    }

    return branches;
  }

  /**
   * Retrieve statuses for a given SHA. Unrelated to the editorial workflow
   * concept of entry "status". Useful for things like deploy preview links.
   */
  async getStatuses(collectionName: string, slug: string) {
    const contentKey = this.generateContentKey(collectionName, slug);
    const branch = branchFromContentKey(contentKey);
    const pullRequest = await this.getBranchPullRequest(branch);
    const sha = pullRequest.head.sha;
    const resp: { statuses: GitHubCommitStatus[] } = await this.request(
      `${this.originRepoURL}/commits/${sha}/status`,
    );
    return resp.statuses.map(s => ({
      context: s.context,
      // eslint-disable-next-line @typescript-eslint/camelcase
      target_url: s.target_url,
      state:
        s.state === GitHubCommitStatusState.Success ? PreviewState.Success : PreviewState.Other,
    }));
  }

  async persistFiles(entry: Entry | null, mediaFiles: AssetProxy[], options: PersistOptions) {
    const files = entry ? mediaFiles.concat(entry) : mediaFiles;
    const uploadPromises = files.map(file => this.uploadBlob(file));
    await Promise.all(uploadPromises);

    if (!options.useWorkflow) {
      return this.getDefaultBranch()
        .then(branchData =>
          this.updateTree(branchData.commit.sha, files as { sha: string; path: string }[]),
        )
        .then(changeTree => this.commit(options.commitMessage, changeTree))
        .then(response => this.patchBranch(this.branch, response.sha));
    } else {
      const mediaFilesList = (mediaFiles as { sha: string; path: string }[]).map(
        ({ sha, path }) => ({
          path: trimStart(path, '/'),
          sha,
        }),
      );
      return this.editorialWorkflowGit(
        files as TreeFile[],
        entry as Entry,
        mediaFilesList,
        options,
      );
    }
  }

  async getFileSha(path: string, { repoURL = this.repoURL, branch = this.branch } = {}) {
    /**
     * We need to request the tree first to get the SHA. We use extended SHA-1
     * syntax (<rev>:<path>) to get a blob from a tree without having to recurse
     * through the tree.
     */

    const pathArray = path.split('/');
    const filename = last(pathArray);
    const directory = initial(pathArray).join('/');
    const fileDataPath = encodeURIComponent(directory);
    const fileDataURL = `${repoURL}/git/trees/${branch}:${fileDataPath}`;

    const result: Octokit.GitGetTreeResponse = await this.request(fileDataURL, {
      cache: 'no-store',
    });
    const file = result.tree.find(file => file.path === filename);
    if (file) {
      return file.sha;
    } else {
      throw new APIError('Not Found', 404, API_NAME);
    }
  }

  deleteFile(path: string, message: string) {
    if (this.useOpenAuthoring) {
      return Promise.reject('Cannot delete published entries as an Open Authoring user!');
    }

    const branch = this.branch;

    return this.getFileSha(path, { branch }).then(sha => {
      const params: { sha: string; message: string; branch: string; author?: { date: string } } = {
        sha,
        message,
        branch,
      };
      const opts = { method: 'DELETE', params };
      if (this.commitAuthor) {
        opts.params.author = {
          ...this.commitAuthor,
          date: new Date().toISOString(),
        };
      }
      const fileURL = `${this.repoURL}/contents/${path}`;
      return this.request(fileURL, opts);
    });
  }

  async createBranchAndPullRequest(branchName: string, sha: string, commitMessage: string) {
    await this.createBranch(branchName, sha);
    return this.createPR(commitMessage, branchName);
  }

  async updatePullRequestLabels(number: number, labels: string[]) {
    await this.request(`${this.repoURL}/issues/${number}/labels`, {
      method: 'PUT',
      body: JSON.stringify({ labels }),
    });
  }

  async editorialWorkflowGit(
    files: TreeFile[],
    entry: Entry,
    mediaFilesList: MediaFile[],
    options: PersistOptions,
  ) {
    const contentKey = this.generateContentKey(options.collectionName as string, entry.slug);
    const branch = branchFromContentKey(contentKey);
    const unpublished = options.unpublished || false;
    if (!unpublished) {
      const branchData = await this.getDefaultBranch();
      const changeTree = await this.updateTree(branchData.commit.sha, files);
      const commitResponse = await this.commit(options.commitMessage, changeTree);

      if (this.useOpenAuthoring) {
        await this.createBranch(branch, commitResponse.sha);
      } else {
        const pr = await this.createBranchAndPullRequest(
          branch,
          commitResponse.sha,
          options.commitMessage,
        );
        await this.setPullRequestStatus(pr, options.status || this.initialWorkflowStatus);
      }
    } else {
      // Entry is already on editorial review workflow - commit to existing branch
      const { files: diffs } = await this.getDifferences(this.branch, branch, this.repoURL);

      // mark media files to remove
      const mediaFilesToRemove: { path: string; sha: string | null }[] = [];
      for (const diff of diffs) {
        if (!mediaFilesList.some(file => file.path === diff.filename)) {
          mediaFilesToRemove.push({ path: diff.filename, sha: null });
        }
      }

      // rebase the branch before applying new changes
      const rebasedHead = await this.rebaseBranch(branch);
      const treeFiles = mediaFilesToRemove.concat(files);
      const changeTree = await this.updateTree(rebasedHead.sha, treeFiles);
      const commit = await this.commit(options.commitMessage, changeTree);

      return this.patchBranch(branch, commit.sha, { force: true });
    }
  }

  async getDifferences(from: string, to: string, repoURL: string) {
    const result: Octokit.ReposCompareCommitsResponse = await this.request(
      `${repoURL}/compare/${from}...${to}`,
    );
    return result;
  }

  async rebaseSingleCommit(baseCommit: GitHubCompareCommit, commit: GitHubCompareCommit) {
    // first get the diff between the commits
    const result = await this.getDifferences(commit.parents[0].sha, commit.sha, this.repoURL);
    const files = getTreeFiles(result.files as GitHubCompareFiles);

    // create a tree with baseCommit as the base with the diff applied
    const tree = await this.updateTree(baseCommit.sha, files);
    const { message, author, committer } = commit.commit;

    // create a new commit from the updated tree
    return (this.createCommit(
      message,
      tree.sha,
      [baseCommit.sha],
      author,
      committer,
    ) as unknown) as GitHubCompareCommit;
  }

  /**
   * Rebase an array of commits one-by-one, starting from a given base SHA
   */
  async rebaseCommits(baseCommit: GitHubCompareCommit, commits: GitHubCompareCommits) {
    /**
     * If the parent of the first commit already matches the target base,
     * return commits as is.
     */
    if (commits.length === 0 || commits[0].parents[0].sha === baseCommit.sha) {
      const head = last(commits) as GitHubCompareCommit;
      return head;
    } else {
      /**
       * Re-create each commit over the new base, applying each to the previous,
       * changing only the parent SHA and tree for each, but retaining all other
       * info, such as the author/committer data.
       */
      const newHeadPromise = commits.reduce((lastCommitPromise, commit) => {
        return lastCommitPromise.then(newParent => {
          const parent = newParent;
          const commitToRebase = commit;
          return this.rebaseSingleCommit(parent, commitToRebase);
        });
      }, Promise.resolve(baseCommit));
      return newHeadPromise;
    }
  }

  async rebaseBranch(branch: string) {
    try {
      // Get the diff between the default branch the published branch
      const { base_commit: baseCommit, commits } = await this.getDifferences(
        this.branch,
        await this.getHeadReference(branch),
        this.originRepoURL,
      );
      // Rebase the branch based on the diff
      const rebasedHead = await this.rebaseCommits(baseCommit, commits);
      return rebasedHead;
    } catch (error) {
      console.error(error);
      throw error;
    }
  }

  async setPullRequestStatus(pullRequest: GitHubPull, newStatus: string) {
    const labels = [
      ...pullRequest.labels.filter(label => !isCMSLabel(label.name)).map(l => l.name),
      statusToLabel(newStatus),
    ];
    await this.updatePullRequestLabels(pullRequest.number, labels);
  }

  async updateUnpublishedEntryStatus(collectionName: string, slug: string, newStatus: string) {
    const contentKey = this.generateContentKey(collectionName, slug);
    const branch = branchFromContentKey(contentKey);
    const pullRequest = await this.getBranchPullRequest(branch);

    if (!this.useOpenAuthoring) {
      await this.setPullRequestStatus(pullRequest, newStatus);
    } else {
      if (status === 'pending_publish') {
        throw new Error('Open Authoring entries may not be set to the status "pending_publish".');
      }

      if (pullRequest.number !== MOCK_PULL_REQUEST) {
        const { state } = pullRequest;
        if (state === PullRequestState.Open && newStatus === 'draft') {
          await this.closePR(pullRequest.number);
        }
        if (state === PullRequestState.Closed && newStatus === 'pending_review') {
          await this.openPR(pullRequest.number);
        }
      } else if (newStatus === 'pending_review') {
        const branch = branchFromContentKey(contentKey);
        // get the first commit message as the pr title
        const diff = await this.getDifferences(this.branch, branch, this.repoURL);
        const title = diff.commits[0]?.commit?.message || API.DEFAULT_COMMIT_MESSAGE;
        await this.createPR(title, branch);
      }
    }
  }

  async deleteUnpublishedEntry(collectionName: string, slug: string) {
    const contentKey = this.generateContentKey(collectionName, slug);
    const branch = branchFromContentKey(contentKey);

    const pullRequest = await this.getBranchPullRequest(branch);
    if (pullRequest.number !== MOCK_PULL_REQUEST) {
      await this.closePR(pullRequest.number);
    }
    await this.deleteBranch(branch);
  }

  async publishUnpublishedEntry(collectionName: string, slug: string) {
    const contentKey = this.generateContentKey(collectionName, slug);
    const branch = branchFromContentKey(contentKey);

    const pullRequest = await this.getBranchPullRequest(branch);
    await this.mergePR(pullRequest);
    await this.deleteBranch(branch);
  }

  async createRef(type: string, name: string, sha: string) {
    const result: Octokit.GitCreateRefResponse = await this.request(`${this.repoURL}/git/refs`, {
      method: 'POST',
      body: JSON.stringify({ ref: `refs/${type}/${name}`, sha }),
    });
    return result;
  }

  async patchRef(type: string, name: string, sha: string, opts: { force?: boolean } = {}) {
    const force = opts.force || false;
    const result: Octokit.GitUpdateRefResponse = await this.request(
      `${this.repoURL}/git/refs/${type}/${encodeURIComponent(name)}`,
      {
        method: 'PATCH',
        body: JSON.stringify({ sha, force }),
      },
    );
    return result;
  }

  deleteRef(type: string, name: string) {
    return this.request(`${this.repoURL}/git/refs/${type}/${encodeURIComponent(name)}`, {
      method: 'DELETE',
    });
  }

  async getBranch(branch: string) {
    const result: Octokit.ReposGetBranchResponse = await this.request(
      `${this.repoURL}/branches/${encodeURIComponent(branch)}`,
    );
    return result;
  }

  async getDefaultBranch() {
    const result: Octokit.ReposGetBranchResponse = await this.request(
      `${this.originRepoURL}/branches/${encodeURIComponent(this.branch)}`,
    );
    return result;
  }

  createBranch(branchName: string, sha: string) {
    return this.createRef('heads', branchName, sha);
  }

  assertCmsBranch(branchName: string) {
    return branchName.startsWith(`${CMS_BRANCH_PREFIX}/`);
  }

  patchBranch(branchName: string, sha: string, opts: { force?: boolean } = {}) {
    const force = opts.force || false;
    if (force && !this.assertCmsBranch(branchName)) {
      throw Error(`Only CMS branches can be force updated, cannot force update ${branchName}`);
    }
    return this.patchRef('heads', branchName, sha, { force });
  }

  deleteBranch(branchName: string) {
    return this.deleteRef('heads', branchName).catch((err: Error) => {
      // If the branch doesn't exist, then it has already been deleted -
      // deletion should be idempotent, so we can consider this a
      // success.
      if (err.message === 'Reference does not exist') {
        return Promise.resolve();
      }
      console.error(err);
      return Promise.reject(err);
    });
  }

  async getHeadReference(head: string) {
    return `${this.repoOwner}:${head}`;
  }

  async createPR(title: string, head: string) {
    const result: Octokit.PullsCreateResponse = await this.request(`${this.originRepoURL}/pulls`, {
      method: 'POST',
      body: JSON.stringify({
        title,
        body: DEFAULT_PR_BODY,
        head: await this.getHeadReference(head),
        base: this.branch,
      }),
    });

    return result;
  }

  async openPR(number: number) {
    console.log('%c Re-opening PR', 'line-height: 30px;text-align: center;font-weight: bold');
    const result: Octokit.PullsUpdateBranchResponse = await this.request(
      `${this.originRepoURL}/pulls/${number}`,
      {
        method: 'PATCH',
        body: JSON.stringify({
          state: PullRequestState.Open,
        }),
      },
    );
    return result;
  }

  async closePR(number: number) {
    console.log('%c Deleting PR', 'line-height: 30px;text-align: center;font-weight: bold');
    const result: Octokit.PullsUpdateBranchResponse = await this.request(
      `${this.originRepoURL}/pulls/${number}`,
      {
        method: 'PATCH',
        body: JSON.stringify({
          state: PullRequestState.Closed,
        }),
      },
    );
    return result;
  }

  async mergePR(pullrequest: GitHubPull) {
    console.log('%c Merging PR', 'line-height: 30px;text-align: center;font-weight: bold');
    try {
      const result: Octokit.PullsMergeResponse = await this.request(
        `${this.originRepoURL}/pulls/${pullrequest.number}/merge`,
        {
          method: 'PUT',
          body: JSON.stringify({
            // eslint-disable-next-line @typescript-eslint/camelcase
            commit_message: MERGE_COMMIT_MESSAGE,
            sha: pullrequest.head.sha,
            // eslint-disable-next-line @typescript-eslint/camelcase
            merge_method: this.mergeMethod,
          }),
        },
      );
      return result;
    } catch (error) {
      if (error instanceof APIError && error.status === 405) {
        return this.forceMergePR(pullrequest);
      } else {
        throw error;
      }
    }
  }

  async forceMergePR(pullRequest: GitHubPull) {
    const result = await this.getDifferences(
      pullRequest.base.sha,
      pullRequest.head.sha,
      this.repoURL,
    );
    const files = getTreeFiles(result.files as GitHubCompareFiles);

    let commitMessage = 'Automatically generated. Merged on Netlify CMS\n\nForce merge of:';
    files.forEach(file => {
      commitMessage += `\n* "${file.path}"`;
    });
    console.log(
      '%c Automatic merge not possible - Forcing merge.',
      'line-height: 30px;text-align: center;font-weight: bold',
    );
    return this.getDefaultBranch()
      .then(branchData => this.updateTree(branchData.commit.sha, files))
      .then(changeTree => this.commit(commitMessage, changeTree))
      .then(response => this.patchBranch(this.branch, response.sha));
  }

  toBase64(str: string) {
    return Promise.resolve(Base64.encode(str));
  }

  uploadBlob(item: { raw?: string; sha?: string; toBase64?: () => Promise<string> }) {
    const content = result(item, 'toBase64', partial(this.toBase64, item.raw as string));

    return content.then(contentBase64 =>
      this.request(`${this.repoURL}/git/blobs`, {
        method: 'POST',
        body: JSON.stringify({
          content: contentBase64,
          encoding: 'base64',
        }),
      }).then(response => {
        item.sha = response.sha;
        return item;
      }),
    );
  }

  async updateTree(baseSha: string, files: { path: string; sha: string | null }[]) {
    const tree: TreeEntry[] = files.map(file => ({
      path: trimStart(file.path, '/'),
      mode: '100644',
      type: 'blob',
      sha: file.sha,
    }));

    const newTree = await this.createTree(baseSha, tree);
    return { ...newTree, parentSha: baseSha };
  }

  async createTree(baseSha: string, tree: TreeEntry[]) {
    const result: Octokit.GitCreateTreeResponse = await this.request(`${this.repoURL}/git/trees`, {
      method: 'POST',
      // eslint-disable-next-line @typescript-eslint/camelcase
      body: JSON.stringify({ base_tree: baseSha, tree }),
    });
    return result;
  }

  commit(message: string, changeTree: { parentSha?: string; sha: string }) {
    const parents = changeTree.parentSha ? [changeTree.parentSha] : [];
    return this.createCommit(message, changeTree.sha, parents);
  }

  async createCommit(
    message: string,
    treeSha: string,
    parents: string[],
    author?: GitHubAuthor,
    committer?: GitHubCommitter,
  ) {
    const result: Octokit.GitCreateCommitResponse = await this.request(
      `${this.repoURL}/git/commits`,
      {
        method: 'POST',
        body: JSON.stringify({ message, tree: treeSha, parents, author, committer }),
      },
    );
    return result;
  }
}