/**
 * Standalone Adversarial Stress-Test Harness for Milestone M1
 * (DRLG Wilderness Remediation: RNG Stream Isolation, Parameter Validation & Multi-Seed Sensitivity)
 *
 * Verifies:
 * 1. rng.fork('actN-topography') isolation:
 *    - Drawing numbers from child fork does not advance master rng.seed / rng.state.
 *    - Stream reproducibility, cross-label independence, interleaved execution equivalence.
 * 2. Strict parameter validation:
 *    - stampAct5SiegeStrips rejects missing/invalid Rng or WildernessStats with Error.
 *    - stampAct3KurastCauseway rejects missing/invalid Rng with Error.
 * 3. Seed sensitivity across 16 arbitrary random seeds (10+ required) across Acts 2..5 outdoor levels:
 *    - 100% collision-free layout digests for procedural outdoor levels.
 *    - Re-run determinism invariance.
 * 4. Act 1 Bit-Identical Regression Guard:
 *    - All Act 1 outdoor levels remain 100% bit-identical to canonical baseline.
 */

import { existsSync } from 'node:fs'
import { Rng } from '../src/game/rng.ts'
import { stampAct5SiegeStrips } from '../src/game/wilderness-siege.ts'
import { stampAct3KurastCauseway } from '../src/game/wilderness-acts.ts'
import {
  createCanvas,
  generateWilderness,
  type Canvas,
  type WildernessPiece,
  type WildernessSubstitution,
  type WildernessStats,
} from '../src/game/wilderness.ts'
import { MountedArchives } from '../src/mpq/mount.ts'
import { MpqArchive } from '../src/mpq/archive.ts'
import { fileSource } from '../src/mpq/file-source.ts'
import { loadActTables, parseTable, cell, tileMemberPath, type D2Table } from '../src/game/acts.ts'
import { decodeDs1, type Ds1, type Ds1Cell } from '../src/formats/ds1.ts'

/* ------------------------------------------------------------------------- *
 * Canonical Hasher (FNV-1a)
 * ------------------------------------------------------------------------- */

class Hasher {
  private hash = 2166136261

  push(value: number): this {
    const word = Math.trunc(value) | 0
    for (let byte = 0; byte < 4; byte += 1) {
      this.hash ^= (word >>> (byte * 8)) & 0xff
      this.hash = Math.imul(this.hash, 16777619) >>> 0
    }
    return this
  }

  get digest(): string {
    return (this.hash >>> 0).toString(16).padStart(8, '0')
  }
}

function canonicalHash(level: Ds1): string {
  const hasher = new Hasher()
  hasher.push(level.version).push(level.width).push(level.height).push(level.act)
  hasher.push(level.substitutionType).push(level.wallLayers).push(level.floorLayers)
  for (let y = 0; y < level.height; y += 1) {
    const row = level.cells[y]
    if (row === undefined) continue
    for (let x = 0; x < level.width; x += 1) {
      const cellRecord = row[x]
      if (cellRecord === undefined) continue
      for (const wall of cellRecord.walls) {
        hasher.push(wall.prop1).push(wall.sequence).push(wall.style).push(wall.type).push(wall.hidden ? 1 : 0)
      }
      for (const floor of cellRecord.floors) {
        hasher.push(floor.prop1).push(floor.sequence).push(floor.style).push(floor.hidden ? 1 : 0)
      }
      for (const shadow of cellRecord.shadows) hasher.push(shadow.prop1).push(shadow.sequence).push(shadow.style)
      for (const substitution of cellRecord.substitutions) hasher.push(substitution.value)
    }
  }
  for (const object of level.objects) hasher.push(object.type).push(object.id).push(object.x).push(object.y).push(object.flags)
  return hasher.digest
}

/* ------------------------------------------------------------------------- *
 * Test Assertions Harness
 * ------------------------------------------------------------------------- */

let totalAssertions = 0
let passedAssertions = 0
let failedAssertions = 0

function assert(condition: boolean, description: string, details?: string): void {
  totalAssertions += 1
  if (condition) {
    passedAssertions += 1
  } else {
    failedAssertions += 1
    console.error(`[FAIL] ${description}`)
    if (details) console.error(`       Details: ${details}`)
  }
}

function assertThrows(fn: () => void, expectedMessagePattern: RegExp, description: string): void {
  totalAssertions += 1
  try {
    fn()
    failedAssertions += 1
    console.error(`[FAIL] ${description} - Expected function to throw, but it returned normally`)
  } catch (err: unknown) {
    if (err instanceof Error && expectedMessagePattern.test(err.message)) {
      passedAssertions += 1
    } else {
      failedAssertions += 1
      console.error(`[FAIL] ${description} - Threw unexpected error: ${(err as Error)?.message}`)
    }
  }
}

/* ------------------------------------------------------------------------- *
 * Part 1: RNG Stream Isolation Stress Tests
 * ------------------------------------------------------------------------- */

console.log('=================================================================')
console.log('PART 1: RNG Stream Isolation Stress Tests (Mulberry32 fork)')
console.log('=================================================================')

const TEST_SEEDS_BASE = [0x12345678, 0xdeadbeef, 0x301cd095, 0x416d61c5, 0x7fffffff]

for (const initialSeed of TEST_SEEDS_BASE) {
  const master = new Rng(initialSeed)
  const control = new Rng(initialSeed)

  const initialMasterSeed = master.seed
  assert(initialMasterSeed === (initialSeed >>> 0), `Master initial seed matches input (0x${initialSeed.toString(16)})`)

  // Fork child streams
  const child2 = master.fork('act2-topography')
  const child3 = master.fork('act3-topography')
  const child4 = master.fork('act4-topography')
  const child5 = master.fork('act5-topography')

  assert(master.seed === initialMasterSeed, `Creating 4 forks does not change master.seed (0x${initialMasterSeed.toString(16)})`)

  // Draw 50,000 numbers from each child
  for (let i = 0; i < 50000; i += 1) {
    child2.next()
    child2.int(0, 10)
    child3.range(0.0, 1.0)
    child4.chance(0.5)
    child5.pick(['a', 'b', 'c'])
  }

  assert(master.seed === initialMasterSeed, `Drawing 250,000 values from children leaves master.seed strictly unchanged`)

  // Now draw 10,000 numbers from master and control; verify bit-for-bit identity
  let drawsIdentical = true
  for (let i = 0; i < 10000; i += 1) {
    const vMaster = master.next()
    const vControl = control.next()
    if (vMaster !== vControl) {
      drawsIdentical = false
      break
    }
  }
  assert(drawsIdentical, `10,000 draws from master match control 100% bit-for-bit after child execution (seed 0x${initialSeed.toString(16)})`)
}

// Interleaved draw stress test (1,000 random operations)
{
  const master = new Rng(0xcafebebe)
  const control = new Rng(0xcafebebe)
  const child = master.fork('act2-topography')

  let interleavedEqual = true
  for (let step = 0; step < 500; step += 1) {
    // Master draws 3
    for (let m = 0; m < 3; m += 1) {
      if (master.next() !== control.next()) {
        interleavedEqual = false
      }
    }
    // Child draws 17
    for (let c = 0; c < 17; c += 1) {
      child.next()
    }
    // Master draws 2
    for (let m = 0; m < 2; m += 1) {
      if (master.int(1, 100) !== control.int(1, 100)) {
        interleavedEqual = false
      }
    }
  }
  assert(interleavedEqual, 'Interleaved draws between master and child preserve master stream exact identity')
}

// Cross-label distinction test
{
  const root = new Rng(0x1337c0de)
  const f2 = root.fork('act2-topography')
  const f3 = root.fork('act3-topography')
  const f4 = root.fork('act4-topography')
  const f5 = root.fork('act5-topography')

  const seq2 = Array.from({ length: 10 }, () => f2.next())
  const seq3 = Array.from({ length: 10 }, () => f3.next())
  const seq4 = Array.from({ length: 10 }, () => f4.next())
  const seq5 = Array.from({ length: 10 }, () => f5.next())

  assert(seq2[0] !== seq3[0] && seq3[0] !== seq4[0] && seq4[0] !== seq5[0], 'Forks with different labels produce distinct initial draws')
  assert(f2.seed !== f3.seed && f3.seed !== f4.seed && f4.seed !== f5.seed, 'Forks with different labels produce distinct child initial seeds')

  // Reproducibility test: identical label + identical master state -> identical child draws
  const rootClone = new Rng(0x1337c0de)
  const f2Clone = rootClone.fork('act2-topography')
  const seq2Clone = Array.from({ length: 10 }, () => f2Clone.next())
  assert(JSON.stringify(seq2) === JSON.stringify(seq2Clone), 'Fork with identical label and identical master state produces identical sequences')
}

console.log(`[PASS] Part 1 completed: ${passedAssertions}/${totalAssertions} assertions held.`)

/* ------------------------------------------------------------------------- *
 * Part 2: Strict Parameter Validation Stress Tests
 * ------------------------------------------------------------------------- */

console.log('\n=================================================================')
console.log('PART 2: Strict Parameter Validation Stress Tests')
console.log('=================================================================')

const mockCanvas: Canvas = createCanvas(64, 64, 1, 1, 1)
const validRng = new Rng(42)
const validStats: WildernessStats = {
  substitutions: [],
  notes: [],
} as unknown as WildernessStats

// 2.1 stampAct5SiegeStrips invalid RNG tests
const invalidRngs = [
  null,
  undefined,
  42,
  0,
  -1,
  'new Rng(42)',
  {},
  { next: () => 0.5 },
  false,
  true,
  NaN,
  Symbol('rng'),
]

for (const badRng of invalidRngs) {
  assertThrows(
    () => stampAct5SiegeStrips(mockCanvas, [], badRng as unknown as Rng, validStats),
    /missing required Rng parameter/,
    `stampAct5SiegeStrips rejects invalid Rng: ${String(badRng)}`,
  )
}

// 2.2 stampAct5SiegeStrips invalid WildernessStats tests
const invalidStats = [null, undefined, false, 0, '']
for (const badStats of invalidStats) {
  assertThrows(
    () => stampAct5SiegeStrips(mockCanvas, [], validRng, badStats as unknown as WildernessStats),
    /missing required WildernessStats parameter/,
    `stampAct5SiegeStrips rejects invalid stats: ${String(badStats)}`,
  )
}

// 2.3 stampAct3KurastCauseway invalid RNG tests
for (const badRng of invalidRngs) {
  assertThrows(
    () => stampAct3KurastCauseway(mockCanvas, [], badRng as unknown as Rng, validStats),
    /missing required Rng instance/,
    `stampAct3KurastCauseway rejects invalid Rng: ${String(badRng)}`,
  )
}

console.log(`[PASS] Part 2 completed: ${passedAssertions}/${totalAssertions} assertions held.`)

/* ------------------------------------------------------------------------- *
 * Part 3: Seed Sensitivity Across 16 Arbitrary Random Seeds (Acts 2..5)
 * ------------------------------------------------------------------------- */

console.log('\n=================================================================')
console.log('PART 3: Multi-Seed Sensitivity across 16 Seeds in Acts 2..5')
console.log('=================================================================')

const MULTI_SEEDS = [
  0x12345678,
  0x9abcdef0,
  0xdeadbeef,
  0x301cd095,
  0x416d61c5,
  0x5a5a5a5a,
  0xa5a5a5a5,
  0x11223344,
  0x55667788,
  0x99aabbcc,
  0xddeeff00,
  0x01020304,
  0x05060708,
  0x090a0b0c,
  0x0d0e0f10,
  0x7fffffff,
] as const

assert(MULTI_SEEDS.length >= 10, `Testing across ${MULTI_SEEDS.length} arbitrary random seeds (>= 10 required)`)

async function runSeedSensitivityTests(): Promise<void> {
  if (!existsSync('samples/d2/d2data.mpq')) {
    console.warn('[WARN] samples/d2/d2data.mpq not found, running hermetic mock tests only.')
    return
  }

  const archives = new MountedArchives()
  for (const name of ['d2data.mpq', 'd2exp.mpq', 'Patch_D2.mpq']) {
    try {
      archives.add(name, await MpqArchive.open(await fileSource(`samples/d2/${name}`)))
    } catch {
      // ignore
    }
  }

  const actTables = await loadActTables(archives)
  const tables = {
    levels: actTables.levels,
    lvltypes: actTables.lvltypes,
    lvlprest: actTables.lvlprest,
  }
  const lvlsub = parseTable(await archives.read('data\\global\\excel\\LvlSub.txt'))

  const ds1Cache = new Map<string, Ds1>()
  async function loadDs1(relative: string): Promise<Ds1> {
    const member = tileMemberPath(relative)
    const cached = ds1Cache.get(member)
    if (cached !== undefined) return cached
    const decoded = decodeDs1(await archives.read(member))
    ds1Cache.set(member, decoded)
    return decoded
  }

  async function rowDs1s(table: D2Table, row: readonly string[]): Promise<Ds1[]> {
    const levels: Ds1[] = []
    for (let slot = 1; slot <= 6; slot += 1) {
      const value = cell(table, row, `File${String(slot)}`)
      if (value === '' || value === '0') continue
      levels.push(await loadDs1(value))
    }
    return levels
  }

  const WILDERNESS_PIECE_FAMILIES: Readonly<Record<string, readonly string[]>> = {
    'Act 1 - Wilderness': [
      'Act 1 - Wild', 'Act 1 - Town 1 Transition', 'Act 1 - Cave Entrance',
      'Act 1 - DOE Entrance', 'Act 1 - Corral Fill', 'Act 1 - Fence Fill',
      'Act 1 - River', 'Act 1 - Bridge', 'Act 1 - Bivouac', 'Act 1 - Pond',
      'Act 1 - Swamp Fill', 'Act 1 - Stone Fill', 'Act 1 - Cottages',
      'Act 1 - Fallen Camp', 'Act 1 - Camp', 'Act 1 - Cairn Stones',
      'Act 1 - Inifus', 'Act 1 - Tower', 'Act 1 - Ruin', 'Act 1 - Tree Fill',
      'Act 1 - Graveyard',
    ],
    'Act 2 - Desert': ['Act 2 - Desert'],
    'Act 3 - Jungle': ['Act 3 - Jungle'],
    'Act 3 - Kurast': ['Act 3 - Burst', 'Act 3 - Burbs', 'Act 3 - Clearing', 'Act 3 - Slums', 'Act 3 - Metro', 'Act 3 - Travincal', 'Act 3 - Bridge'],
    'Act 4 - Mesa': ['Act 4 - Mesa', 'Act 4 - Fortress', 'Act 4 - Pits', 'Act 4 - Bridge'],
    'Act 4 - Lava': ['Act 4 - Lava', 'Act 4 - Diablo'],
    'Act 5 - Siege': ['Act 5 - Siege'],
    'Act 5 - Barricade': ['Act 5 - Barricade'],
  }

  async function buildWildernessPieces(levelTypeName: string): Promise<WildernessPiece[]> {
    const families = WILDERNESS_PIECE_FAMILIES[levelTypeName] ?? []
    const pieces: WildernessPiece[] = []
    for (const row of tables.lvlprest.rows) {
      const name = cell(tables.lvlprest, row, 'Name')
      if (!families.some(family => name.startsWith(family))) continue
      if (levelTypeName === 'Act 5 - Barricade' && name.includes('Snow')) continue
      const levels = await rowDs1s(tables.lvlprest, row)
      if (levels.length === 0) continue
      const isBorder = levelTypeName === 'Act 1 - Wilderness' ? /\bBorder\b/i.test(name) : /border|cliff/i.test(name)
      pieces.push({ name, levels, border: isBorder })
    }
    return pieces
  }

  async function buildSubstitutions(type: number): Promise<WildernessSubstitution[]> {
    if (type < 0) return []
    const rows: WildernessSubstitution[] = []
    for (const row of lvlsub.rows) {
      if (Number(cell(lvlsub, row, 'Type')) !== type) continue
      const file = cell(lvlsub, row, 'File')
      if (file === '' || file === '0') continue
      const levels = [await loadDs1(file)]
      rows.push({
        name: cell(lvlsub, row, 'Name'),
        type,
        gridSize: Number(cell(lvlsub, row, 'GridSize')) || 1,
        bordType: Number(cell(lvlsub, row, 'BordType')),
        dt1Mask: Number(cell(lvlsub, row, 'Dt1Mask')) || 0,
        prob: [0, 1, 2, 3, 4].map(i => Number(cell(lvlsub, row, `Prob${String(i)}`)) || 0),
        trials: [0, 1, 2, 3, 4].map(i => Number(cell(lvlsub, row, `Trials${String(i)}`)) || 0),
        max: [0, 1, 2, 3, 4].map(i => Number(cell(lvlsub, row, `Max${String(i)}`)) || 0),
        levels,
      })
    }
    return rows
  }

  async function generateLevel(levelId: number, seed: number): Promise<Ds1> {
    const levelRow = tables.levels.rows.find(row => Number(cell(tables.levels, row, 'Id')) === levelId)!
    const typeId = cell(tables.levels, levelRow, 'LevelType')
    const typeRow = tables.lvltypes.rows.find(row => cell(tables.lvltypes, row, 'Id') === typeId)
    const levelTypeName = typeRow ? cell(tables.lvltypes, typeRow, 'Name') : ''
    const name = cell(tables.levels, levelRow, 'Name')
    const sizeX = Number(cell(tables.levels, levelRow, 'SizeX'))
    const sizeY = Number(cell(tables.levels, levelRow, 'SizeY'))
    const subType = Number(cell(tables.levels, levelRow, 'SubType'))
    const subShrine = Number(cell(tables.levels, levelRow, 'SubShrine'))
    const subTheme = Number(cell(tables.levels, levelRow, 'SubTheme'))

    const pieces = await buildWildernessPieces(levelTypeName)
    const subs = await buildSubstitutions(subType)
    const shrineSubs = await buildSubstitutions(subShrine)

    const result = generateWilderness({
      levelId,
      levelName: name,
      levelTypeName,
      sizeX,
      sizeY,
      subType,
      subTheme: Math.max(0, subTheme),
      seed,
      pieces,
      substitutions: subs,
      shrineSubstitutions: shrineSubs,
    })
    return result.level
  }

  // Test across Acts 2..5 procedural levels
  const targetLevels = [
    { act: 2, id: 41, name: 'Rocky Waste' },
    { act: 2, id: 42, name: 'Dry Hills' },
    { act: 2, id: 43, name: 'Far Oasis' },
    { act: 2, id: 44, name: 'Lost City' },
    { act: 2, id: 45, name: 'Valley of Snakes' },
    { act: 2, id: 46, name: 'Canyon of the Magi' },
    { act: 3, id: 76, name: 'Spider Forest' },
    { act: 3, id: 77, name: 'Great Marsh' },
    { act: 3, id: 78, name: 'Flayer Jungle' },
    { act: 3, id: 79, name: 'Lower Kurast' },
    { act: 3, id: 80, name: 'Kurast Bazaar' },
    { act: 3, id: 81, name: 'Upper Kurast' },
    { act: 4, id: 104, name: 'Outer Steppes' },
    { act: 4, id: 105, name: 'Plains of Despair' },
    { act: 4, id: 106, name: 'City of the Damned' },
    { act: 5, id: 110, name: 'Bloody Foothills' },
    { act: 5, id: 111, name: 'Frigid Highlands' },
    { act: 5, id: 112, name: 'Arreat Plateau' },
    { act: 5, id: 117, name: 'Frozen Tundra' },
    { act: 5, id: 134, name: 'Nihlathak Temple Garden' },
  ]

  for (const lvl of targetLevels) {
    const digests: string[] = []
    for (const seed of MULTI_SEEDS) {
      const ds1 = await generateLevel(lvl.id, seed)
      const digest = canonicalHash(ds1)
      digests.push(digest)
    }

    const uniqueCount = new Set(digests).size
    const passedUniq = uniqueCount === MULTI_SEEDS.length
    assert(
      passedUniq,
      `Level ${lvl.id} (${lvl.name}, Act ${lvl.act}): ${uniqueCount}/${MULTI_SEEDS.length} unique digests (100% collision-free)`,
      `Expected ${MULTI_SEEDS.length} unique digests, got ${uniqueCount}. Digests: ${digests.join(', ')}`,
    )

    // Verify determinism on seed 0
    const rerun = await generateLevel(lvl.id, MULTI_SEEDS[0])
    const rerunDigest = canonicalHash(rerun)
    const passedDeterminism = rerunDigest === digests[0]
    assert(
      passedDeterminism,
      `Level ${lvl.id} (${lvl.name}): Determinism hold (re-run digest ${rerunDigest} === ${digests[0]})`,
    )

    console.log(`  ✓ Level ${String(lvl.id).padStart(3, ' ')} (${lvl.name.padEnd(24, ' ')} Act ${lvl.act}): ${uniqueCount}/${MULTI_SEEDS.length} collision-free digests | determinism OK`)
  }

  /* ------------------------------------------------------------------------- *
   * Part 4: Act 1 Bit-Identical Regression Guard
   * ------------------------------------------------------------------------- */

  console.log('\n=================================================================')
  console.log('PART 4: Act 1 Bit-Identical Regression Guard')
  console.log('=================================================================')

  const ACT1_BASELINE_HASHES: Readonly<Record<number, readonly [string, string, string]>> = {
    2: ['7b00cdd4', 'ecf76547', 'cc83418d'], // Blood Moor
    3: ['0724e8be', '3df74523', '3312522f'], // Cold Plains
    4: ['a7d44b10', '23f8b483', '57598911'], // Stony Field
    5: ['d867cfdc', '1fc6c41c', '2093e6c7'], // Dark Wood
    6: ['79b5d613', '731695ab', 'eddff41d'], // Black Marsh
    7: ['3838630e', 'b19aac67', 'dff3927c'], // Tamoe Highland
    17: ['ef7f1b99', '7deeb4c7', 'dbfe44d3'], // Burial Grounds
    39: ['63daa9b7', '32ea40dc', '406a3493'], // Secret Cow Level
  }
  const CANONICAL_TEST_SEEDS = [0x301cd095, 0x416d61c5, 0xdeadbeef] as const

  const act1Levels = [2, 3, 4, 5, 6, 7, 17, 39]
  for (const levelId of act1Levels) {
    const expected = ACT1_BASELINE_HASHES[levelId]!
    const actual: string[] = []

    for (const seed of CANONICAL_TEST_SEEDS) {
      const level = await generateLevel(levelId, seed)
      actual.push(canonicalHash(level))
    }

    const matches = JSON.stringify(actual) === JSON.stringify(expected)
    assert(
      matches,
      `Act 1 Level ${levelId} matches baseline table 100% bit-for-bit: [${actual.join(', ')}] === [${expected.join(', ')}]`,
    )
    console.log(`  ✓ Act 1 Level ${String(levelId).padStart(2, ' ')} bit-identical match: [${actual.join(', ')}]`)
  }
}

async function main(): Promise<void> {
  const startTime = Date.now()
  await runSeedSensitivityTests()
  const durationSec = ((Date.now() - startTime) / 1000).toFixed(2)

  console.log('\n=================================================================')
  console.log('SUMMARY OF EMPIRICAL ADVERSARIAL STRESS TEST')
  console.log('=================================================================')
  console.log(`Total Assertions: ${totalAssertions}`)
  console.log(`Passed:           ${passedAssertions}`)
  console.log(`Failed:           ${failedAssertions}`)
  console.log(`Execution Time:   ${durationSec}s`)

  if (failedAssertions > 0) {
    console.error('\n>>> VERDICT: CHALLENGE_FAILED <<<')
    process.exit(1)
  } else {
    console.log('\n>>> VERDICT: APPROVE <<<')
    process.exit(0)
  }
}

main().catch(err => {
  console.error('Fatal error during stress test execution:', err)
  process.exit(1)
})