import { afterEach, describe, expect, it, vi } from 'vitest'
import { getPullRequestDraftContext } from './pull-request-context'

type GitExec = Parameters<typeof getPullRequestDraftContext>[0]

afterEach(() => {
  vi.restoreAllMocks()
})

function createContextInput(base = 'main') {
  return {
    base,
    currentTitle: 'Existing title',
    currentBody: 'Existing body',
    currentDraft: false
  }
}

describe('getPullRequestDraftContext error handling', () => {
  // Why: error and validation cases live outside the remote-resolution matrix
  // so each suite stays focused while preserving the same git command coverage.
  it('does not run rebase before collecting PR context', async () => {
    const execGit = vi.fn<GitExec>(async (args) => {
      if (args[0] === 'fetch') {
        return { stdout: '', stderr: '' }
      }
      if (args[0] === 'remote') {
        return { stdout: 'origin\n', stderr: '' }
      }
      if (args[0] === 'for-each-ref') {
        return { stdout: 'origin/main\n', stderr: '' }
      }
      if (args[0] === 'branch') {
        return { stdout: 'feature\n', stderr: '' }
      }
      if (args[0] === 'rebase') {
        throw new Error('Generate must not rebase the live worktree')
      }
      if (args[0] === 'merge-base') {
        return { stdout: 'abc123\n', stderr: '' }
      }
      if (args[0] === 'log') {
        return { stdout: '- feat: change\n', stderr: '' }
      }
      if (args[0] === 'diff') {
        return { stdout: 'M\tREADME.md\n', stderr: '' }
      }
      throw new Error(`Unexpected git args: ${args.join(' ')}`)
    })

    await expect(getPullRequestDraftContext(execGit, createContextInput())).resolves.toMatchObject({
      branch: 'feature'
    })
    expect(execGit).not.toHaveBeenCalledWith(expect.arrayContaining(['rebase']), expect.anything())
  })

  it('stops generation when the relevant base fetch fails', async () => {
    const execGit = vi.fn<GitExec>(async (args) => {
      if (args[0] === 'remote') {
        return { stdout: 'origin\nstale-fork\n', stderr: '' }
      }
      if (args[0] === 'for-each-ref') {
        return { stdout: 'origin/main\nstale-fork/main\n', stderr: '' }
      }
      if (args[0] === 'fetch') {
        if (args[2] !== 'origin') {
          throw new Error(`Fetched unrelated remote: ${args.join(' ')}`)
        }
        throw new Error(
          'Command failed: git fetch --no-tags origin +refs/heads/main:refs/remotes/origin/main\nfatal: unable to access origin'
        )
      }
      throw new Error(`Unexpected git args: ${args.join(' ')}`)
    })

    await expect(getPullRequestDraftContext(execGit, createContextInput())).rejects.toThrow(
      'Fetch before generating PR details failed: fatal: unable to access origin'
    )
  })

  it('handles newline-heavy remote state and fetch errors without line-array splitting', async () => {
    const splitSpy = vi.spyOn(String.prototype, 'split')
    const execGit = vi.fn<GitExec>(async (args) => {
      if (args[0] === 'remote') {
        return { stdout: `${'\r\n'.repeat(10_000)}origin\r\n`, stderr: '' }
      }
      if (args[0] === 'for-each-ref') {
        return { stdout: `${'\r\n'.repeat(10_000)}origin/main\r\n`, stderr: '' }
      }
      if (args[0] === 'fetch') {
        throw new Error(
          `Command failed: git fetch\r\n${'remote: progress\r\n'.repeat(10_000)}fatal: unable to access origin\r\n`
        )
      }
      throw new Error(`Unexpected git args: ${args.join(' ')}`)
    })

    await expect(getPullRequestDraftContext(execGit, createContextInput())).rejects.toThrow(
      'Fetch before generating PR details failed: fatal: unable to access origin'
    )

    const usedLineSplit = splitSpy.mock.calls.some(
      ([separator]) =>
        (typeof separator === 'string' && separator === '\n') ||
        (separator instanceof RegExp && separator.source === '\\r?\\n')
    )
    expect(usedLineSplit).toBe(false)
  })

  it('returns null without running git when the base is invalid', async () => {
    const execGit = vi.fn<GitExec>()

    await expect(getPullRequestDraftContext(execGit, createContextInput('--main'))).resolves.toBe(
      null
    )
    expect(execGit).not.toHaveBeenCalled()
  })
})