import { mkdtemp, rm, writeFile } from 'node:fs/promises'
import { tmpdir } from 'node:os'
import { join } from 'node:path'
import { afterEach, describe, expect, it } from 'vitest'
import { simpleGit } from 'simple-git'
import { readFile } from 'node:fs/promises'
import { existsSync } from 'node:fs'
import { classify, discard, load, stage } from '../src/main/git-service'

describe('classify', () => {
  it('reads the index code as staged, working code as unstaged', () => {
    expect(classify('M', ' ')).toEqual([{ letter: 'M', staged: true }])
    expect(classify(' ', 'M')).toEqual([{ letter: 'M', staged: false }])
    expect(classify('A', ' ')).toEqual([{ letter: 'A', staged: true }])
    expect(classify('D', ' ')).toEqual([{ letter: 'D', staged: true }])
    expect(classify('R', ' ')).toEqual([{ letter: 'R', staged: true }])
  })
  it('treats untracked as a new (A) unstaged file', () => {
    expect(classify('?', '?')).toEqual([{ letter: 'A', staged: false }])
  })
  it('splits a staged-then-edited file into two rows', () => {
    expect(classify('M', 'M')).toEqual([
      { letter: 'M', staged: true },
      { letter: 'M', staged: false },
    ])
    expect(classify('A', 'M')).toEqual([
      { letter: 'A', staged: true },
      { letter: 'M', staged: false },
    ])
    expect(classify('M', 'D')).toEqual([
      { letter: 'M', staged: true },
      { letter: 'D', staged: false },
    ])
  })
  it('keeps a merge conflict as one row', () => {
    expect(classify('U', 'U')).toEqual([{ letter: 'M', staged: true }])
    expect(classify('A', 'A')).toEqual([{ letter: 'M', staged: true }])
    expect(classify('D', 'D')).toEqual([{ letter: 'M', staged: true }])
  })
})

describe('load (integration against a temp repo)', () => {
  let dir = ''
  afterEach(async () => { if (dir) await rm(dir, { recursive: true, force: true }) })

  async function repo(): Promise<string> {
    const d = await mkdtemp(join(tmpdir(), 'helder-git-'))
    const g = simpleGit(d)
    await g.init()
    await g.addConfig('user.email', 't@example.com')
    await g.addConfig('user.name', 'Test')
    await g.addConfig('commit.gpgsign', 'false')
    await writeFile(join(d, 'a.txt'), '1\n2\n3\n')
    await g.add('.')
    await g.commit('init')
    return d
  }

  it('returns null for a non-repo directory', async () => {
    dir = await mkdtemp(join(tmpdir(), 'helder-nogit-'))
    expect(await load(dir)).toBeNull()
  })

  it('reports a modified file with HEAD-vs-worktree text', async () => {
    dir = await repo()
    await writeFile(join(dir, 'a.txt'), '1\nX\n3\n')
    const res = await load(dir)
    expect(res).not.toBeNull()
    expect(res!.branch).toBeTruthy()
    const a = res!.changes.find((c) => c.path === 'a.txt')
    expect(a?.status).toBe('M')
    expect(a?.staged).toBe(false)
    expect(a?.original).toBe('1\n2\n3\n')
    expect(a?.updated).toBe('1\nX\n3\n')
  })

  it('reports an untracked file as new (A), original empty', async () => {
    dir = await repo()
    await writeFile(join(dir, 'new.txt'), 'fresh\n')
    const res = await load(dir)
    const n = res!.changes.find((c) => c.path === 'new.txt')
    expect(n?.status).toBe('A')
    expect(n?.staged).toBe(false)
    expect(n?.original).toBe('')
    expect(n?.updated).toBe('fresh\n')
  })

  it('reflects staging', async () => {
    dir = await repo()
    await writeFile(join(dir, 'a.txt'), '1\n2\n3\n4\n')
    await stage(dir, ['a.txt'])
    const res = await load(dir)
    expect(res!.changes.find((c) => c.path === 'a.txt')?.staged).toBe(true)
  })

  it('shows a staged-then-edited file in both groups, each with its own pair', async () => {
    dir = await repo()
    await writeFile(join(dir, 'a.txt'), '1\nSTAGED\n3\n')
    await stage(dir, ['a.txt'])
    await writeFile(join(dir, 'a.txt'), '1\nSTAGED\n3\n4\n')
    const res = await load(dir)
    const rows = res!.changes.filter((c) => c.path === 'a.txt')
    expect(rows).toHaveLength(2)

    // Staged row: HEAD -> index. It must NOT include the newer edit.
    const s = rows.find((c) => c.staged)!
    expect(s.original).toBe('1\n2\n3\n')
    expect(s.updated).toBe('1\nSTAGED\n3\n')

    // Unstaged row: index -> disk. Only the newer edit.
    const w = rows.find((c) => !c.staged)!
    expect(w.original).toBe('1\nSTAGED\n3\n')
    expect(w.updated).toBe('1\nSTAGED\n3\n4\n')
  })

  it('gives a staged-new file that was edited again both rows', async () => {
    dir = await repo()
    await writeFile(join(dir, 'fresh.txt'), 'one\n')
    await stage(dir, ['fresh.txt'])
    await writeFile(join(dir, 'fresh.txt'), 'one\ntwo\n')
    const res = await load(dir)
    const rows = res!.changes.filter((c) => c.path === 'fresh.txt')
    expect(rows.map((r) => [r.status, r.staged])).toEqual([['A', true], ['M', false]])
    expect(rows[0].original).toBe('')
    expect(rows[0].updated).toBe('one\n')
    expect(rows[1].original).toBe('one\n')
    expect(rows[1].updated).toBe('one\ntwo\n')
  })

  it('keeps one row when a file is only staged', async () => {
    dir = await repo()
    await writeFile(join(dir, 'a.txt'), '1\n2\n3\n4\n')
    await stage(dir, ['a.txt'])
    const rows = (await load(dir))!.changes.filter((c) => c.path === 'a.txt')
    expect(rows).toHaveLength(1)
    expect(rows[0].staged).toBe(true)
    expect(rows[0].original).toBe('1\n2\n3\n')
    expect(rows[0].updated).toBe('1\n2\n3\n4\n')
  })

  it('discard reverts a modified tracked file to HEAD', async () => {
    dir = await repo()
    await writeFile(join(dir, 'a.txt'), '1\nCHANGED\n3\n')
    await discard(dir, ['a.txt'])
    expect(await readFile(join(dir, 'a.txt'), 'utf8')).toBe('1\n2\n3\n')
    const res = await load(dir)
    expect(res!.changes.find((c) => c.path === 'a.txt')).toBeUndefined()
  })

  it('discard removes a new (untracked) file from disk', async () => {
    dir = await repo()
    await writeFile(join(dir, 'new.txt'), 'fresh\n')
    await discard(dir, ['new.txt'])
    expect(existsSync(join(dir, 'new.txt'))).toBe(false)
  })

  it('discard removes a staged-new file', async () => {
    dir = await repo()
    await writeFile(join(dir, 'staged-new.txt'), 'x\n')
    await stage(dir, ['staged-new.txt'])
    await discard(dir, ['staged-new.txt'])
    expect(existsSync(join(dir, 'staged-new.txt'))).toBe(false)
    const res = await load(dir)
    expect(res!.changes.find((c) => c.path === 'staged-new.txt')).toBeUndefined()
  })
})