import { differenceInDays } from 'date-fns'
import type { FilteredRepository, Repository } from '../types/index.js'
import type { GitHubClient } from './github.js'

export async function filterInactiveRepositories(
  repositories: Repository[],
  githubClient: GitHubClient,
): Promise<FilteredRepository[]> {
  const now = new Date()
  const oneYearAgo = new Date(
    now.getFullYear() - 1,
    now.getMonth(),
    now.getDate(),
  )

  // First filter by stars and forks
  const candidateRepos = repositories.filter(
    (repo) => repo.stargazers_count === 0 && repo.forks_count === 0,
  )

  // Process all candidates in parallel
  const repoPromises = candidateRepos.map(async (repo) => {
    // Get last commit date
    const lastCommitDate = await githubClient.getLastCommitDate(
      repo.owner.login,
      repo.name,
    )

    // If no commits found, use pushed_at date
    const lastActivityDate =
      lastCommitDate || (repo.pushed_at ? new Date(repo.pushed_at) : null)

    if (!lastActivityDate || lastActivityDate < oneYearAgo) {
      const daysSinceLastCommit = lastActivityDate
        ? differenceInDays(now, lastActivityDate)
        : null

      return {
        ...repo,
        lastCommitDate: lastActivityDate,
        daysSinceLastCommit,
      } as FilteredRepository
    }

    return null
  })

  const results = await Promise.all(repoPromises)
  return results.filter((repo): repo is FilteredRepository => repo !== null)
}

export function sortByInactivity(
  repos: FilteredRepository[],
): FilteredRepository[] {
  return [...repos].sort((a, b) => {
    // Repos with no activity go first
    if (!a.lastCommitDate && b.lastCommitDate) return -1
    if (a.lastCommitDate && !b.lastCommitDate) return 1
    if (!a.lastCommitDate && !b.lastCommitDate) return 0

    // Sort by oldest activity first
    return a.lastCommitDate!.getTime() - b.lastCommitDate!.getTime()
  })
}