import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest'
import fs from 'node:fs/promises'
import os from 'node:os'
import path from 'node:path'
import { execFile } from 'node:child_process'
import { promisify } from 'node:util'
import type { Config, LiveSessionInfo } from '../src/types.js'
import type { HistorySession } from '../src/http/history.js'

// ── mock history.listSessions so the real ~/.claude/projects never pollutes ──────
// (vitest hoists vi.mock; the factory may only reference vars prefixed "mock".)
const mockListSessions = vi.fn(async (): Promise<HistorySession[]> => [])
vi.mock('../src/http/history.js', () => ({
  listSessions: (...a: unknown[]) => mockListSessions(...a),
}))

const { parseGitHead, buildProjects, _clearProjectCache } = await import('../src/http/projects.js')

const execFileP = promisify(execFile)

// ── helpers ─────────────────────────────────────────────────────────────────────

function makeCfg(overrides: Partial<Config>): Config {
  return {
    port: 3000,
    bindHost: '0.0.0.0',
    shellPath: '/bin/zsh',
    homeDir: '/home/tester',
    idleTtlMs: 1000,
    scrollbackBytes: 1024,
    maxPayloadBytes: 1024,
    wsPath: '/term',
    maxSessions: 50,
    maxMsgsPerSec: 2000,
    permTimeoutMs: 1000,
    reapIntervalMs: 1000,
    previewBytes: 1024,
    useTmux: false,
    allowedOrigins: [],
    projectRoots: [],
    projectScanDepth: 4,
    projectScanTtlMs: 0, // default OFF so each test re-scans deterministically
    projectDirtyCheck: false,
    ...overrides,
  }
}

function makeLive(over: { id: string; cwd: string | null } & Partial<LiveSessionInfo>): LiveSessionInfo {
  return {
    id: over.id,
    createdAt: over.createdAt ?? 1000,
    clientCount: over.clientCount ?? 1,
    status: over.status ?? 'unknown',
    exited: over.exited ?? false,
    cwd: over.cwd,
    cols: over.cols ?? 80,
    rows: over.rows ?? 24,
  }
}

async function makeRepo(dir: string, branch: string): Promise<void> {
  await fs.mkdir(path.join(dir, '.git'), { recursive: true })
  await fs.writeFile(path.join(dir, '.git', 'HEAD'), `ref: refs/heads/${branch}\n`)
}

async function gitAvailable(): Promise<boolean> {
  try {
    await execFileP('git', ['--version'])
    return true
  } catch {
    return false
  }
}

let tmp: string

beforeEach(async () => {
  _clearProjectCache()
  mockListSessions.mockReset()
  mockListSessions.mockResolvedValue([])
  tmp = await fs.mkdtemp(path.join(os.tmpdir(), 'projtest-'))
})

afterEach(async () => {
  _clearProjectCache()
  await fs.rm(tmp, { recursive: true, force: true })
})

// ── parseGitHead (pure) ──────────────────────────────────────────────────────────

describe('parseGitHead', () => {
  it('extracts a simple branch name', () => {
    expect(parseGitHead('ref: refs/heads/main\n')).toBe('main')
  })

  it('extracts a branch name with slashes', () => {
    expect(parseGitHead('ref: refs/heads/feature/x\n')).toBe('feature/x')
  })

  it('returns null for a detached HEAD (bare 40-hex sha)', () => {
    expect(parseGitHead('a'.repeat(40) + '\n')).toBeNull()
  })

  it('returns null for empty / junk / non-heads refs', () => {
    expect(parseGitHead('')).toBeNull()
    expect(parseGitHead('garbage\n')).toBeNull()
    expect(parseGitHead('ref: refs/tags/v1\n')).toBeNull()
  })
})

// ── buildProjects: discovery (real temp dir) ─────────────────────────────────────

describe('buildProjects — discovery', () => {
  it('finds git repos with correct names/branches, skips node_modules, respects depth', async () => {
    await makeRepo(path.join(tmp, 'repoA'), 'main') // depth 1
    await makeRepo(path.join(tmp, 'sub', 'repoB'), 'dev') // depth 2
    await makeRepo(path.join(tmp, 'sub', 'deep', 'repoC'), 'x') // depth 3 -> excluded
    await makeRepo(path.join(tmp, 'node_modules', 'pkg'), 'y') // node_modules -> skipped

    const cfg = makeCfg({ projectRoots: [tmp], projectScanDepth: 2, projectDirtyCheck: false })
    const out = await buildProjects(cfg, [])
    const byName = new Map(out.map((p) => [p.name, p]))

    expect([...byName.keys()].sort()).toEqual(['repoA', 'repoB'])
    expect(byName.get('repoA')).toMatchObject({
      isGit: true,
      branch: 'main',
      path: path.join(tmp, 'repoA'),
      sessions: [],
    })
    expect(byName.get('repoB')!.branch).toBe('dev')
    expect(byName.has('repoC')).toBe(false) // too deep
    expect(byName.has('pkg')).toBe(false) // node_modules
  })

  it('records a root that is itself a git repo and does not descend into it', async () => {
    await makeRepo(tmp, 'main')
    await makeRepo(path.join(tmp, 'nested'), 'dev') // inside a repo -> not descended

    const cfg = makeCfg({ projectRoots: [tmp], projectScanDepth: 4, projectDirtyCheck: false })
    const out = await buildProjects(cfg, [])

    expect(out.map((p) => p.path)).toEqual([tmp])
    expect(out[0]!.branch).toBe('main')
  })

  it('leaves branch undefined when .git/HEAD is missing/unreadable', async () => {
    await fs.mkdir(path.join(tmp, 'bare', '.git'), { recursive: true }) // .git dir, no HEAD
    const cfg = makeCfg({ projectRoots: [tmp], projectScanDepth: 2, projectDirtyCheck: false })
    const out = await buildProjects(cfg, [])
    const bare = out.find((p) => p.name === 'bare')!
    expect(bare.isGit).toBe(true)
    expect(bare.branch).toBeUndefined()
  })

  it('does not follow symlinks', async () => {
    const other = await fs.mkdtemp(path.join(os.tmpdir(), 'projtest-link-'))
    try {
      await makeRepo(path.join(other, 'repoS'), 'main')
      try {
        await fs.symlink(other, path.join(tmp, 'linked'), 'dir')
      } catch {
        return // symlinks not permitted in this environment
      }
      const cfg = makeCfg({ projectRoots: [tmp], projectScanDepth: 4, projectDirtyCheck: false })
      const out = await buildProjects(cfg, [])
      expect(out.some((p) => p.name === 'repoS')).toBe(false)
    } finally {
      await fs.rm(other, { recursive: true, force: true })
    }
  })

  it('returns [] for an unreadable / missing root (never throws)', async () => {
    const cfg = makeCfg({
      projectRoots: [path.join(tmp, 'does-not-exist')],
      projectScanDepth: 2,
      projectDirtyCheck: false,
    })
    await expect(buildProjects(cfg, [])).resolves.toEqual([])
  })
})

// ── buildProjects: live-session merge ────────────────────────────────────────────

describe('buildProjects — session merge', () => {
  it('merges sessions into the owning project by cwd === path or under path', async () => {
    await makeRepo(path.join(tmp, 'repoA'), 'main')
    const repoPath = path.join(tmp, 'repoA')
    const cfg = makeCfg({ projectRoots: [tmp], projectScanDepth: 2, projectDirtyCheck: false })

    const live: LiveSessionInfo[] = [
      makeLive({ id: 's-exact', cwd: repoPath, status: 'working', clientCount: 2, createdAt: 111 }),
      makeLive({ id: 's-under', cwd: path.join(repoPath, 'src', 'http'), status: 'idle' }),
      makeLive({ id: 's-other', cwd: path.join(tmp, 'elsewhere') }),
      makeLive({ id: 's-null', cwd: null }),
    ]

    const out = await buildProjects(cfg, live)
    const repoA = out.find((p) => p.name === 'repoA')!

    expect(repoA.sessions.map((s) => s.id).sort()).toEqual(['s-exact', 's-under'])
    expect(repoA.sessions.find((s) => s.id === 's-exact')).toEqual({
      id: 's-exact',
      title: 'repoA',
      status: 'working',
      clientCount: 2,
      createdAt: 111,
      exited: false,
    })
    expect(repoA.sessions.find((s) => s.id === 's-under')!.title).toBe('http')
  })

  it('re-merges live sessions FRESH on every call (discovery is cached)', async () => {
    await makeRepo(path.join(tmp, 'repoA'), 'main')
    const repoPath = path.join(tmp, 'repoA')
    const cfg = makeCfg({
      projectRoots: [tmp],
      projectScanDepth: 2,
      projectDirtyCheck: false,
      projectScanTtlMs: 60_000, // keep discovery cached across calls
    })

    const first = await buildProjects(cfg, [])
    expect(first.find((p) => p.name === 'repoA')!.sessions).toEqual([])

    const second = await buildProjects(cfg, [makeLive({ id: 's1', cwd: repoPath })])
    expect(second.find((p) => p.name === 'repoA')!.sessions.map((s) => s.id)).toEqual(['s1'])

    const third = await buildProjects(cfg, [])
    expect(third.find((p) => p.name === 'repoA')!.sessions).toEqual([])
  })
})

// ── buildProjects: history merge + sorting ───────────────────────────────────────

describe('buildProjects — history merge & sorting', () => {
  it('adds history-only cwds as projects and sets lastActiveMs on discovered repos', async () => {
    await makeRepo(path.join(tmp, 'repoA'), 'main')
    const repoPath = path.join(tmp, 'repoA')
    const histDir = await fs.mkdtemp(path.join(os.tmpdir(), 'projtest-hist-'))
    try {
      mockListSessions.mockResolvedValue([
        { id: 'h1', cwd: repoPath, project: 'repoA', mtimeMs: 5000, preview: '' },
        { id: 'h2', cwd: repoPath, project: 'repoA', mtimeMs: 9000, preview: '' },
        { id: 'h3', cwd: histDir, project: path.basename(histDir), mtimeMs: 3000, preview: '' },
        { id: 'h4', cwd: '', project: 'unknown', mtimeMs: 1, preview: '' },
      ])

      const cfg = makeCfg({ projectRoots: [tmp], projectScanDepth: 2, projectDirtyCheck: false })
      const out = await buildProjects(cfg, [])

      const repoA = out.find((p) => p.name === 'repoA')!
      expect(repoA.lastActiveMs).toBe(9000) // newest of h1/h2

      const hist = out.find((p) => p.path === histDir)!
      expect(hist).toBeDefined()
      expect(hist.isGit).toBe(false)
      expect(hist.lastActiveMs).toBe(3000)

      expect(out.some((p) => p.path === '')).toBe(false) // empty cwd ignored
      expect(out[0]!.name).toBe('repoA') // 9000 > 3000
    } finally {
      await fs.rm(histDir, { recursive: true, force: true })
    }
  })

  it('sorts by lastActiveMs desc, undefined last, name asc tiebreak', async () => {
    await makeRepo(path.join(tmp, 'zzz'), 'main') // no history -> undefined
    await makeRepo(path.join(tmp, 'aaa'), 'main') // no history -> undefined
    await makeRepo(path.join(tmp, 'mmm'), 'main') // has history -> first
    mockListSessions.mockResolvedValue([
      { id: 'h', cwd: path.join(tmp, 'mmm'), project: 'mmm', mtimeMs: 1000, preview: '' },
    ])

    const cfg = makeCfg({ projectRoots: [tmp], projectScanDepth: 2, projectDirtyCheck: false })
    const out = await buildProjects(cfg, [])

    expect(out.map((p) => p.name)).toEqual(['mmm', 'aaa', 'zzz'])
  })
})

// ── buildProjects: in-flight promise deduplication (Finding 4) ─────────────────────

describe('buildProjects — concurrent cache-miss deduplication', () => {
  it('two concurrent cold-cache calls return consistent results (no corrupt state)', async () => {
    await makeRepo(path.join(tmp, 'repoA'), 'main')
    await makeRepo(path.join(tmp, 'repoB'), 'dev')
    const cfg = makeCfg({ projectRoots: [tmp], projectScanDepth: 2, projectDirtyCheck: false })

    // Both calls start concurrently while cache is cold.
    const [a, b] = await Promise.all([buildProjects(cfg, []), buildProjects(cfg, [])])

    const aNames = a.map((p) => p.name).sort()
    const bNames = b.map((p) => p.name).sort()
    expect(aNames).toEqual(['repoA', 'repoB'])
    expect(bNames).toEqual(aNames)
  })

  it('second concurrent call gets the same result as the first (in-flight reuse)', async () => {
    await makeRepo(path.join(tmp, 'repoA'), 'main')
    const cfg = makeCfg({
      projectRoots: [tmp],
      projectScanDepth: 2,
      projectDirtyCheck: false,
      projectScanTtlMs: 60_000,
    })

    // Start first call, immediately start second — second should share the in-flight promise.
    const first = buildProjects(cfg, [])
    const second = buildProjects(cfg, []) // cache still cold at this synchronous point
    const [r1, r2] = await Promise.all([first, second])
    expect(r1.map((p) => p.name)).toContain('repoA')
    expect(r2.map((p) => p.name)).toEqual(r1.map((p) => p.name))
  })
})

// ── buildProjects: dirty check (real git, when available) ─────────────────────────

describe('buildProjects — dirty check', () => {
  it('computes dirty via git status only when projectDirtyCheck is true', async () => {
    if (!(await gitAvailable())) return // git not installed -> skip
    const repo = path.join(tmp, 'gitrepo')
    await fs.mkdir(repo, { recursive: true })
    await execFileP('git', ['init', '-q'], { cwd: repo })
    await execFileP('git', ['config', 'user.email', 't@t.local'], { cwd: repo })
    await execFileP('git', ['config', 'user.name', 'tester'], { cwd: repo })

    const cfg = makeCfg({ projectRoots: [tmp], projectScanDepth: 2, projectDirtyCheck: true })

    // clean repo -> dirty false
    let out = await buildProjects(cfg, [])
    const clean = out.find((p) => p.name === 'gitrepo')!
    expect(clean.dirty).toBe(false)
    expect(clean.branch).toBeTruthy()

    // untracked file -> dirty true
    await fs.writeFile(path.join(repo, 'a.txt'), 'hi')
    _clearProjectCache()
    out = await buildProjects(cfg, [])
    expect(out.find((p) => p.name === 'gitrepo')!.dirty).toBe(true)
  })

  it('never spawns git (dirty undefined) when projectDirtyCheck is false', async () => {
    await makeRepo(path.join(tmp, 'repoA'), 'main')
    const cfg = makeCfg({ projectRoots: [tmp], projectScanDepth: 2, projectDirtyCheck: false })
    const out = await buildProjects(cfg, [])
    expect(out.find((p) => p.name === 'repoA')!.dirty).toBeUndefined()
  })
})