/**
 * test/config.test.ts — T4: config module unit tests (TDD)
 *
 * Strategy:
 *   - Mock `node:os` networkInterfaces to inject fake NICs (M1)
 *   - Assert defaults, env overrides, validation errors, allowedOrigins shape
 *
 * vi.mock is hoisted to the top of the file by vitest — the factory runs before
 * any import, so config.ts will receive the mocked os module.
 */

import { describe, it, expect, vi, beforeEach } from 'vitest'
import type { NetworkInterfaceInfo } from 'node:os'

// ── mock node:os ─────────────────────────────────────────────────────────────
// vi.mock is hoisted by vitest, so this factory runs before config.ts is imported.

const mockNetworkInterfaces = vi.fn<[], ReturnType<typeof import('node:os').networkInterfaces>>()
mockNetworkInterfaces.mockReturnValue({})

const mockHomedir = vi.fn<[], string>()
mockHomedir.mockReturnValue('/home/testuser')

vi.mock('node:os', async (importOriginal) => {
  const actual = await importOriginal<typeof import('node:os')>()
  return {
    ...actual,
    default: {
      ...actual.default,
      homedir: () => mockHomedir(),
      networkInterfaces: () => mockNetworkInterfaces(),
    },
    homedir: () => mockHomedir(),
    networkInterfaces: () => mockNetworkInterfaces(),
  }
})

// ── mock tmux availability so resolveUseTmux's auto-detect is deterministic ──
const mockTmuxAvailable = vi.fn<[], boolean>()
mockTmuxAvailable.mockReturnValue(false)
vi.mock('../src/session/tmux.js', () => ({
  tmuxAvailable: () => mockTmuxAvailable(),
  tmuxName: (id: string) => `web_${id}`,
  hasSession: () => false,
  killSession: () => undefined,
}))

// Import config AFTER mock is set up (dynamic import ensures mock applies)
const { loadConfig } = await import('../src/config.js')

// Helper: build a fake IPv4 NIC entry
function makeNic(address: string, internal: boolean): NetworkInterfaceInfo {
  return {
    address,
    netmask: '255.255.255.0',
    family: 'IPv4',
    mac: '00:00:00:00:00:00',
    internal,
    cidr: `${address}/24`,
  }
}

// ── Default values ────────────────────────────────────────────────────────────
describe('loadConfig — defaults', () => {
  beforeEach(() => {
    mockNetworkInterfaces.mockReturnValue({})
    mockHomedir.mockReturnValue('/home/testuser')
  })

  it('uses PORT 3000', () => {
    const cfg = loadConfig({})
    expect(cfg.port).toBe(3000)
  })

  it('uses BIND_HOST 0.0.0.0', () => {
    const cfg = loadConfig({})
    expect(cfg.bindHost).toBe('0.0.0.0')
  })

  it('uses IDLE_TTL 24h in ms', () => {
    const cfg = loadConfig({})
    expect(cfg.idleTtlMs).toBe(24 * 60 * 60 * 1000)
  })

  it('uses SCROLLBACK_BYTES 2MB', () => {
    const cfg = loadConfig({})
    expect(cfg.scrollbackBytes).toBe(2 * 1024 * 1024)
  })

  it('uses MAX_PAYLOAD_BYTES 1MB', () => {
    const cfg = loadConfig({})
    expect(cfg.maxPayloadBytes).toBe(1 * 1024 * 1024)
  })

  it('uses WS_PATH /term', () => {
    const cfg = loadConfig({})
    expect(cfg.wsPath).toBe('/term')
  })

  it('uses homeDir from os.homedir()', () => {
    mockHomedir.mockReturnValue('/home/testuser')
    const cfg = loadConfig({})
    expect(cfg.homeDir).toBe('/home/testuser')
  })
})

// ── Env overrides ─────────────────────────────────────────────────────────────
describe('loadConfig — env overrides', () => {
  beforeEach(() => {
    mockNetworkInterfaces.mockReturnValue({})
    mockHomedir.mockReturnValue('/home/testuser')
  })

  it('reads PORT from env', () => {
    const cfg = loadConfig({ PORT: '8080' })
    expect(cfg.port).toBe(8080)
  })

  it('reads BIND_HOST from env', () => {
    const cfg = loadConfig({ BIND_HOST: '127.0.0.1' })
    expect(cfg.bindHost).toBe('127.0.0.1')
  })

  it('reads SHELL_PATH from env', () => {
    const cfg = loadConfig({ SHELL_PATH: '/bin/bash' })
    expect(cfg.shellPath).toBe('/bin/bash')
  })

  it('reads IDLE_TTL (seconds) and converts to ms', () => {
    const cfg = loadConfig({ IDLE_TTL: '3600' })
    expect(cfg.idleTtlMs).toBe(3600 * 1000)
  })

  it('reads SCROLLBACK_BYTES from env', () => {
    const cfg = loadConfig({ SCROLLBACK_BYTES: '1048576' })
    expect(cfg.scrollbackBytes).toBe(1048576)
  })

  it('reads MAX_PAYLOAD_BYTES from env', () => {
    const cfg = loadConfig({ MAX_PAYLOAD_BYTES: '524288' })
    expect(cfg.maxPayloadBytes).toBe(524288)
  })

  it('reads WS_PATH from env', () => {
    const cfg = loadConfig({ WS_PATH: '/ws' })
    expect(cfg.wsPath).toBe('/ws')
  })
})

// ── Validation errors ─────────────────────────────────────────────────────────
describe('loadConfig — invalid values throw', () => {
  beforeEach(() => {
    mockNetworkInterfaces.mockReturnValue({})
  })

  it('throws for PORT below 1', () => {
    expect(() => loadConfig({ PORT: '0' })).toThrow()
  })

  it('throws for PORT above 65535', () => {
    expect(() => loadConfig({ PORT: '65536' })).toThrow()
  })

  it('throws for PORT that is not a number', () => {
    expect(() => loadConfig({ PORT: 'abc' })).toThrow()
  })

  it('throws for IDLE_TTL that is not a number', () => {
    expect(() => loadConfig({ IDLE_TTL: 'abc' })).toThrow()
  })

  it('throws for IDLE_TTL that is negative', () => {
    expect(() => loadConfig({ IDLE_TTL: '-1' })).toThrow()
  })

  it('throws for SCROLLBACK_BYTES that is not a number', () => {
    expect(() => loadConfig({ SCROLLBACK_BYTES: 'nope' })).toThrow()
  })

  it('throws for MAX_PAYLOAD_BYTES that is not a number', () => {
    expect(() => loadConfig({ MAX_PAYLOAD_BYTES: 'nope' })).toThrow()
  })
})

// ── allowedOrigins — M1 core tests ──────────────────────────────────────────
describe('loadConfig — allowedOrigins (M1)', () => {
  beforeEach(() => {
    mockNetworkInterfaces.mockReturnValue({})
    mockHomedir.mockReturnValue('/home/testuser')
  })

  it('always includes localhost variants', () => {
    const cfg = loadConfig({})
    const origins = cfg.allowedOrigins
    expect(origins).toContain('http://localhost:3000')
    expect(origins).toContain('http://127.0.0.1:3000')
  })

  it('never contains 0.0.0.0 (M1: bindHost must not bleed in)', () => {
    // even if BIND_HOST is 0.0.0.0 (default)
    const cfg = loadConfig({ BIND_HOST: '0.0.0.0' })
    const hasWildcard = cfg.allowedOrigins.some((o) => o.includes('0.0.0.0'))
    expect(hasWildcard).toBe(false)
  })

  it('includes injected LAN NIC IPv4', () => {
    mockNetworkInterfaces.mockReturnValue({
      en0: [makeNic('192.168.1.100', false)],
    })
    const cfg = loadConfig({})
    expect(cfg.allowedOrigins).toContain('http://192.168.1.100:3000')
  })

  it('includes https:// variant for injected NIC', () => {
    mockNetworkInterfaces.mockReturnValue({
      en0: [makeNic('10.0.0.5', false)],
    })
    const cfg = loadConfig({})
    expect(cfg.allowedOrigins).toContain('https://10.0.0.5:3000')
  })

  it('excludes internal (loopback) NICs from LAN list (127.x added separately)', () => {
    mockNetworkInterfaces.mockReturnValue({
      lo0: [makeNic('127.0.0.1', true)],
    })
    const cfg = loadConfig({})
    // 127.0.0.1 added via loopback constants; no duplicates beyond http+https
    const count127 = cfg.allowedOrigins.filter((o) =>
      o.includes('127.0.0.1'),
    ).length
    // http and https = 2
    expect(count127).toBeLessThanOrEqual(2)
  })

  it('skips IPv6 entries on NICs', () => {
    mockNetworkInterfaces.mockReturnValue({
      en0: [
        {
          address: 'fe80::1',
          netmask: 'ffff:ffff:ffff:ffff::',
          family: 'IPv6',
          mac: '00:00:00:00:00:00',
          internal: false,
          cidr: 'fe80::1/64',
          scopeid: 0,
        } as NetworkInterfaceInfo,
        makeNic('192.168.1.50', false),
      ],
    })
    const cfg = loadConfig({})
    const hasIPv6 = cfg.allowedOrigins.some((o) => o.includes('fe80'))
    expect(hasIPv6).toBe(false)
    expect(cfg.allowedOrigins).toContain('http://192.168.1.50:3000')
  })

  it('merges ALLOWED_ORIGINS env var into the list', () => {
    const extra = 'http://mymac.local:3000,https://mymac.local:3000'
    const cfg = loadConfig({ ALLOWED_ORIGINS: extra })
    expect(cfg.allowedOrigins).toContain('http://mymac.local:3000')
    expect(cfg.allowedOrigins).toContain('https://mymac.local:3000')
  })

  it('respects custom PORT when building origins', () => {
    mockNetworkInterfaces.mockReturnValue({
      en0: [makeNic('172.16.0.1', false)],
    })
    const cfg = loadConfig({ PORT: '4000' })
    expect(cfg.allowedOrigins).toContain('http://172.16.0.1:4000')
    expect(cfg.allowedOrigins).toContain('https://172.16.0.1:4000')
  })

  it('deduplicates origins when ALLOWED_ORIGINS overlaps with derived set', () => {
    const cfg = loadConfig({
      ALLOWED_ORIGINS: 'http://localhost:3000,http://localhost:3000',
    })
    const localhostCount = cfg.allowedOrigins.filter(
      (o) => o === 'http://localhost:3000',
    ).length
    expect(localhostCount).toBe(1)
  })
})

// ── MAX_SESSIONS + new operational constants ──────────────────────────────────
describe('loadConfig — session/rate/timer constants', () => {
  beforeEach(() => {
    mockNetworkInterfaces.mockReturnValue({})
    mockHomedir.mockReturnValue('/home/testuser')
  })

  it('defaults maxSessions to 50', () => {
    expect(loadConfig({}).maxSessions).toBe(50)
  })

  it('reads MAX_SESSIONS from env', () => {
    expect(loadConfig({ MAX_SESSIONS: '20' }).maxSessions).toBe(20)
  })

  it('throws for a non-integer MAX_SESSIONS', () => {
    expect(() => loadConfig({ MAX_SESSIONS: 'lots' })).toThrow()
  })

  it('defaults maxMsgsPerSec to 2000 and reads MAX_MSGS_PER_SEC', () => {
    expect(loadConfig({}).maxMsgsPerSec).toBe(2000)
    expect(loadConfig({ MAX_MSGS_PER_SEC: '500' }).maxMsgsPerSec).toBe(500)
  })

  it('defaults permTimeoutMs / reapIntervalMs / previewBytes and reads overrides', () => {
    const def = loadConfig({})
    expect(def.permTimeoutMs).toBe(5 * 60_000)
    expect(def.reapIntervalMs).toBe(60_000)
    expect(def.previewBytes).toBe(24 * 1024)
    const over = loadConfig({ PERM_TIMEOUT_MS: '1000', REAP_INTERVAL_MS: '2000', PREVIEW_BYTES: '4096' })
    expect(over.permTimeoutMs).toBe(1000)
    expect(over.reapIntervalMs).toBe(2000)
    expect(over.previewBytes).toBe(4096)
  })
})

// ── resolveUseTmux branches (USE_TMUX env) ────────────────────────────────────
describe('loadConfig — resolveUseTmux', () => {
  beforeEach(() => {
    mockNetworkInterfaces.mockReturnValue({})
    mockHomedir.mockReturnValue('/home/testuser')
    mockTmuxAvailable.mockReturnValue(false)
  })

  it.each(['1', 'true', 'on', 'ON', ' True '])('forces tmux ON for %j', (v) => {
    expect(loadConfig({ USE_TMUX: v }).useTmux).toBe(true)
  })

  it.each(['0', 'false', 'off'])('forces tmux OFF for %j', (v) => {
    expect(loadConfig({ USE_TMUX: v }).useTmux).toBe(false)
  })

  it('auto-detects (unset) → true when tmux is available', () => {
    mockTmuxAvailable.mockReturnValue(true)
    expect(loadConfig({}).useTmux).toBe(true)
  })

  it('auto-detects (unset / "auto") → false when tmux is unavailable', () => {
    mockTmuxAvailable.mockReturnValue(false)
    expect(loadConfig({}).useTmux).toBe(false)
    expect(loadConfig({ USE_TMUX: 'auto' }).useTmux).toBe(false)
  })
})

// ── ALLOWED_ORIGINS scheme validation (M1) ────────────────────────────────────
describe('loadConfig — ALLOWED_ORIGINS scheme validation', () => {
  beforeEach(() => {
    mockNetworkInterfaces.mockReturnValue({})
    mockHomedir.mockReturnValue('/home/testuser')
  })

  it('rejects non-http(s) scheme entries (file:, javascript:, bare host)', () => {
    const cfg = loadConfig({
      ALLOWED_ORIGINS: 'file:///etc/passwd,javascript:alert(1),notaurl,http://ok.local:3000',
    })
    expect(cfg.allowedOrigins).toContain('http://ok.local:3000')
    expect(cfg.allowedOrigins.some((o) => o.startsWith('file:'))).toBe(false)
    expect(cfg.allowedOrigins.some((o) => o.startsWith('javascript:'))).toBe(false)
    expect(cfg.allowedOrigins).not.toContain('notaurl')
  })

  it('keeps valid https entries', () => {
    const cfg = loadConfig({ ALLOWED_ORIGINS: 'https://phone.local:3000' })
    expect(cfg.allowedOrigins).toContain('https://phone.local:3000')
  })
})

// ── Immutability ──────────────────────────────────────────────────────────────
describe('loadConfig — returned object is frozen', () => {
  beforeEach(() => {
    mockNetworkInterfaces.mockReturnValue({})
    mockHomedir.mockReturnValue('/home/testuser')
  })

  it('result is Object.frozen', () => {
    const cfg = loadConfig({})
    expect(Object.isFrozen(cfg)).toBe(true)
  })

  it('allowedOrigins array is frozen', () => {
    const cfg = loadConfig({})
    expect(Object.isFrozen(cfg.allowedOrigins)).toBe(true)
  })
})