import * as core from '@actions/core'
import {Octokit, RestEndpointMethodTypes} from '@octokit/rest'
import {Unpacked} from './utils'
import moment from 'moment'
import {Property, Sort} from './types'
import {Commits, DiffInfo, filterCommits} from './commits'
import {Options} from './prCollector'

export interface PullRequestInfo {
  number: number
  title: string
  htmlURL: string
  baseBranch: string
  branch?: string
  createdAt: moment.Moment
  mergedAt: moment.Moment | undefined
  mergeCommitSha: string
  author: string
  repoName: string
  labels: string[]
  milestone: string
  body: string
  assignees: string[]
  requestedReviewers: string[]
  approvedReviewers: string[]
  reviews?: CommentInfo[]
  status: 'open' | 'merged'
}

export interface CommentInfo {
  id: number
  htmlURL: string
  submittedAt: moment.Moment | undefined
  author: string
  body: string
  state: string | undefined
}

export const EMPTY_PULL_REQUEST_INFO: PullRequestInfo = {
  number: 0,
  title: '',
  htmlURL: '',
  baseBranch: '',
  mergedAt: undefined,
  createdAt: moment(),
  mergeCommitSha: '',
  author: '',
  repoName: '',
  labels: [],
  milestone: '',
  body: '',
  assignees: [],
  requestedReviewers: [],
  approvedReviewers: [],
  status: 'open'
}

export const EMPTY_COMMENT_INFO: CommentInfo = {
  id: 0,
  htmlURL: '',
  submittedAt: undefined,
  author: '',
  body: '',
  state: undefined
}

type PullData = RestEndpointMethodTypes['pulls']['get']['response']['data']

type PullsListData = RestEndpointMethodTypes['pulls']['list']['response']['data']

type PullReviewsData = RestEndpointMethodTypes['pulls']['listReviews']['response']['data']

export class PullRequests {
  constructor(private octokit: Octokit, private commits: Commits) {}

  async getSingle(owner: string, repo: string, prNumber: number): Promise<PullRequestInfo | null> {
    try {
      const {data} = await this.octokit.pulls.get({
        owner,
        repo,
        pull_number: prNumber
      })

      return mapPullRequest(data)
    } catch (e: any /* eslint-disable-line @typescript-eslint/no-explicit-any */) {
      core.warning(`⚠️ Cannot find PR ${owner}/${repo}#${prNumber} - ${e.message}`)
      return null
    }
  }

  async getBetweenDates(
    owner: string,
    repo: string,
    fromDate: moment.Moment,
    toDate: moment.Moment,
    maxPullRequests: number
  ): Promise<PullRequestInfo[]> {
    const mergedPRs: PullRequestInfo[] = []
    const options = this.octokit.pulls.list.endpoint.merge({
      owner,
      repo,
      state: 'closed',
      sort: 'merged',
      per_page: `${Math.min(100, maxPullRequests)}`,
      direction: 'desc'
    })

    for await (const response of this.octokit.paginate.iterator(options)) {
      const prs: PullsListData = response.data as PullsListData

      for (const pr of prs.filter(p => !!p.merged_at)) {
        mergedPRs.push(mapPullRequest(pr, 'merged'))
      }

      const firstPR = prs[0]
      if (
        firstPR === undefined ||
        (firstPR.merged_at && fromDate.isAfter(moment(firstPR.merged_at))) ||
        mergedPRs.length >= maxPullRequests
      ) {
        if (mergedPRs.length >= maxPullRequests) {
          core.warning(`⚠️ Reached 'maxPullRequests' count ${maxPullRequests}`)
        }

        // bail out early to not keep iterating on PRs super old
        return sortPrs(mergedPRs)
      }
    }

    return sortPrs(mergedPRs)
  }

  async getOpen(owner: string, repo: string, maxPullRequests: number): Promise<PullRequestInfo[]> {
    const openPrs: PullRequestInfo[] = []
    const options = this.octokit.pulls.list.endpoint.merge({
      owner,
      repo,
      state: 'open',
      sort: 'created',
      per_page: '100',
      direction: 'desc'
    })

    for await (const response of this.octokit.paginate.iterator(options)) {
      const prs: PullsListData = response.data as PullsListData

      for (const pr of prs) {
        openPrs.push(mapPullRequest(pr, 'open'))
      }

      const firstPR = prs[0]
      if (firstPR === undefined || openPrs.length >= maxPullRequests) {
        if (openPrs.length >= maxPullRequests) {
          core.warning(`⚠️ Reached 'maxPullRequests' count ${maxPullRequests}`)
        }

        // bail out early to not keep iterating on PRs super old
        return sortPrs(openPrs)
      }
    }

    return sortPrs(openPrs)
  }

  async getReviews(owner: string, repo: string, pr: PullRequestInfo): Promise<void> {
    const options = this.octokit.pulls.listReviews.endpoint.merge({
      owner,
      repo,
      pull_number: pr.number,
      sort: 'created',
      direction: 'desc'
    })
    const prReviews: CommentInfo[] = []
    for await (const response of this.octokit.paginate.iterator(options)) {
      const comments: PullReviewsData = response.data as PullReviewsData

      for (const comment of comments) {
        prReviews.push(mapComment(comment))
      }
    }
    pr.reviews = prReviews
  }

  async getMergedPullRequests(options: Options): Promise<[DiffInfo, PullRequestInfo[]]> {
    const {owner, repo, includeOpen, fetchReviewers, fetchReviews, configuration} = options

    const diffInfo = await this.commits.getCommitHistory(options)
    const commits = diffInfo.commitInfo
    if (commits.length === 0) {
      return [diffInfo, []]
    }

    const firstCommit = commits[0]
    const lastCommit = commits[commits.length - 1]
    let fromDate = firstCommit.date
    const toDate = lastCommit.date

    const maxDays = configuration.max_back_track_time_days
    const maxFromDate = toDate.clone().subtract(maxDays, 'days')
    if (maxFromDate.isAfter(fromDate)) {
      core.info(`⚠️ Adjusted 'fromDate' to go max ${maxDays} back`)
      fromDate = maxFromDate
    }

    core.info(`ℹ️ Fetching PRs between dates ${fromDate.toISOString()} to ${toDate.toISOString()} for ${owner}/${repo}`)

    const pullRequests = await this.getBetweenDates(owner, repo, fromDate, toDate, configuration.max_pull_requests)

    core.info(`ℹ️ Retrieved ${pullRequests.length} PRs for ${owner}/${repo} in date range from API`)

    const prCommits = filterCommits(commits, configuration.exclude_merge_branches)

    core.info(`ℹ️ Retrieved ${prCommits.length} release commits for ${owner}/${repo}`)

    // create array of commits for this release
    const releaseCommitHashes = prCommits.map(commmit => {
      return commmit.sha
    })

    // filter out pull requests not associated with this release
    const mergedPullRequests = pullRequests.filter(pr => {
      return releaseCommitHashes.includes(pr.mergeCommitSha)
    })

    core.info(`ℹ️ Retrieved ${mergedPullRequests.length} merged PRs for ${owner}/${repo}`)

    let allPullRequests = mergedPullRequests
    if (includeOpen) {
      // retrieve all open pull requests
      const openPullRequests = await this.getOpen(owner, repo, configuration.max_pull_requests)

      core.info(`ℹ️ Retrieved ${openPullRequests.length} open PRs for ${owner}/${repo}`)

      // all pull requests
      allPullRequests = allPullRequests.concat(openPullRequests)

      core.info(`ℹ️ Retrieved ${allPullRequests.length} total PRs for ${owner}/${repo}`)
    }

    // retrieve base branches we allow
    const baseBranches = configuration.base_branches
    const baseBranchPatterns = baseBranches.map(baseBranch => {
      return new RegExp(baseBranch.replace('\\\\', '\\'), 'gu')
    })

    // return only prs if the baseBranch is matching the configuration
    const finalPrs = allPullRequests.filter(pr => {
      if (baseBranches.length !== 0) {
        return baseBranchPatterns.some(pattern => {
          return pr.baseBranch.match(pattern) !== null
        })
      }
      return true
    })

    if (baseBranches.length !== 0) {
      core.info(`ℹ️ Retrieved ${finalPrs.length} PRs for ${owner}/${repo} filtered by the 'base_branches' configuration.`)
    }

    // fetch reviewers only if enabled (requires an additional API request per PR)
    if (fetchReviews || fetchReviewers) {
      core.info(`ℹ️ Fetching reviews (or reviewers) was enabled`)
      // update PR information with reviewers who approved
      for (const pr of finalPrs) {
        await this.getReviews(owner, repo, pr)

        const reviews = pr.reviews
        if (reviews && (reviews?.length || 0) > 0) {
          core.info(`ℹ️ Retrieved ${reviews.length || 0} review(s) for PR ${owner}/${repo}/#${pr.number}`)

          // backwards compatiblity
          pr.approvedReviewers = reviews.filter(r => r.state === 'APPROVED').map(r => r.author)
        } else {
          core.debug(`No reviewer(s) for PR ${owner}/${repo}/#${pr.number}`)
        }
      }
    } else {
      core.debug(`ℹ️ Fetching reviews (or reviewers) was disabled`)
    }

    return [diffInfo, finalPrs]
  }
}

function sortPrs(pullRequests: PullRequestInfo[]): PullRequestInfo[] {
  return sortPullRequests(pullRequests, {
    order: 'ASC',
    on_property: 'mergedAt'
  })
}

export function sortPullRequests(pullRequests: PullRequestInfo[], sort: Sort | string): PullRequestInfo[] {
  let sortConfig: Sort

  // legacy handling to support string sort config
  if (typeof sort === 'string') {
    let order: 'ASC' | 'DESC' = 'ASC'
    if (sort.toUpperCase() === 'DESC') order = 'DESC'
    sortConfig = {order, on_property: 'mergedAt'}
  } else {
    sortConfig = sort
  }

  if (sortConfig.order === 'ASC') {
    pullRequests.sort((a, b) => {
      return compare(a, b, sortConfig)
    })
  } else {
    pullRequests.sort((b, a) => {
      return compare(a, b, sortConfig)
    })
  }
  return pullRequests
}

export function compare(a: PullRequestInfo, b: PullRequestInfo, sort: Sort): number {
  if (sort.on_property === 'mergedAt') {
    const aa = a.mergedAt || a.createdAt
    const bb = b.mergedAt || b.createdAt
    if (aa.isBefore(bb)) {
      return -1
    } else if (bb.isBefore(aa)) {
      return 1
    }
    return 0
  } else {
    // only else for now `label`
    return a.title.localeCompare(b.title)
  }
}

/**
 * Helper function to retrieve a property from the PullRequestInfo
 */
export function retrieveProperty(pr: PullRequestInfo, property: Property, useCase: string): string {
  let value: string | number | Set<string> | string[] | undefined = pr[property]
  if (value === undefined) {
    core.warning(`⚠️ the provided property '${property}' for \`${useCase}\` is not valid. Fallback to 'body'`)
    value = pr['body']
  } else if (value instanceof Set) {
    value = Array.from(value).join(',') // join into single string
  } else if (Array.isArray(value)) {
    value = value.join(',') // join into single string
  } else {
    value = value.toString()
  }
  return value
}

// helper function to add a special open label to prs not merged.
function attachSpeciaLabels(status: 'open' | 'merged', labels: string[]): string[] {
  labels.push(`--rcba-${status}`)
  return labels
}

const mapPullRequest = (pr: PullData | Unpacked<PullsListData>, status: 'open' | 'merged' = 'open'): PullRequestInfo => ({
  number: pr.number,
  title: pr.title,
  htmlURL: pr.html_url,
  baseBranch: pr.base.ref,
  branch: pr.head.ref,
  createdAt: moment(pr.created_at),
  mergedAt: pr.merged_at ? moment(pr.merged_at) : undefined,
  mergeCommitSha: pr.merge_commit_sha || '',
  author: pr.user?.login || '',
  repoName: pr.base.repo.full_name,
  labels: attachSpeciaLabels(status, pr.labels?.map(lbl => lbl.name?.toLocaleLowerCase('en') || '') || []),
  milestone: pr.milestone?.title || '',
  body: pr.body || '',
  assignees: pr.assignees?.map(asignee => asignee?.login || '') || [],
  requestedReviewers: pr.requested_reviewers?.map(reviewer => reviewer?.login || '') || [],
  approvedReviewers: [],
  reviews: undefined,
  status
})

const mapComment = (comment: Unpacked<PullReviewsData>): CommentInfo => ({
  id: comment.id,
  htmlURL: comment.html_url,
  submittedAt: comment.submitted_at ? moment(comment.submitted_at) : undefined,
  author: comment.user?.login || '',
  body: comment.body,
  state: comment.state
})