/**
 * Standalone Adversarial Stress-Test Script for Milestone M1
 * Diablo II Web DRLG Engine: Seed Sensitivity & Determinism Profiler
 *
 * Requirements:
 * 1. Stress-test seed sensitivity across 50 distinct random seeds for all legacy-generator outdoor levels (Acts 2..5).
 * 2. Assert determinism: re-running identical seeds yields 100% identical digests.
 * 3. Assert zero collision across different seeds for procedural outdoor levels.
 *
 * Act I's outdoor levels are generated by the DRLG port (src/game/drlg), not by generateWilderness;
 * tests/drlg-act1-oracle.test.ts and tests/drlg-act1-invariants.test.ts cover them.
 *
 * Archetype: EMPIRICAL CHALLENGER
 */

import { existsSync } from 'node:fs'
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 } from '../src/game/acts.ts'
import type { D2Table } from '../src/game/acts.ts'
import { decodeDs1, type Ds1 } from '../src/formats/ds1.ts'
import {
  generateWilderness,
  type WildernessPiece,
  type WildernessSubstitution,
} from '../src/game/wilderness.ts'

/* ------------------------------------------------------------------------- *
 * FNV-1a Canonical Map Hasher
 * ------------------------------------------------------------------------- */

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
}

/* ------------------------------------------------------------------------- *
 * Canonical Master Seeds
 * ------------------------------------------------------------------------- */

const MASTER_SEEDS = [0x301cd095, 0x416d61c5, 0xdeadbeef] as const

/* ------------------------------------------------------------------------- *
 * 50 Distinct Adversarial & Random Seeds
 * ------------------------------------------------------------------------- */

// Construct exactly 50 distinct seeds:
// - 3 canonical master seeds
// - 7 boundary & edge cases (0, 1, 0x7fffffff, 0xffffffff, 42, 1337, 0x5eed1000)
// - 40 pseudo-random high-entropy seeds generated deterministically
function generate50Seeds(): number[] {
  const seedSet = new Set<number>([
    ...MASTER_SEEDS,
    0,
    1,
    0x7fffffff,
    0xffffffff,
    42,
    1337,
    0x5eed1000,
  ])

  // Deterministic LCG to populate the remainder up to 50 distinct seeds
  let state = 0x12345678
  while (seedSet.size < 50) {
    state = Math.imul(state, 1664525) + 1013904223
    seedSet.add(state >>> 0)
  }

  return Array.from(seedSet)
}

/* ------------------------------------------------------------------------- *
 * MPQ Data Cache & Level Resolution
 * ------------------------------------------------------------------------- */

const WILDERNESS_PIECE_FAMILIES: Readonly<Record<string, readonly string[]>> = {
  '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'],
}

// Preset wilderness levels that have fixed layouts by definition
const PRESET_WILDERNESS_LEVELS = new Set<number>([82, 83, 108])

async function runStressTest(): Promise<void> {
  const startTime = Date.now()
  console.log('======================================================================')
  console.log('🔥 EMPIRICAL STRESS-TEST: Milestone M1 DRLG Wilderness Generation')
  console.log('======================================================================\n')

  const samplePath = 'samples/d2/d2data.mpq'
  if (!existsSync(samplePath)) {
    console.error(`❌ MPQ archive missing at ${samplePath}`)
    process.exit(1)
  }

  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 missing optional archive
    }
  }

  const tables = await loadActTables(archives)
  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 piecesCache = new Map<string, WildernessPiece[]>()
  async function getWildernessPieces(levelTypeName: string): Promise<WildernessPiece[]> {
    const cached = piecesCache.get(levelTypeName)
    if (cached !== undefined) return cached

    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 = /border|cliff/i.test(name)
      pieces.push({ name, levels, border: isBorder })
    }
    piecesCache.set(levelTypeName, pieces)
    return pieces
  }

  const subsCache = new Map<number, WildernessSubstitution[]>()
  async function getSubstitutions(type: number): Promise<WildernessSubstitution[]> {
    if (type < 0) return []
    const cached = subsCache.get(type)
    if (cached !== undefined) return cached

    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,
      })
    }
    subsCache.set(type, rows)
    return rows
  }

  // Identify all wilderness levels (DrlgType 3)
  interface WildernessLevelMeta {
    id: number
    name: string
    act: number
    levelTypeName: string
    sizeX: number
    sizeY: number
    subType: number
    subShrine: number
    subTheme: number
    isProcedural: boolean
  }

  const wildernessLevels: WildernessLevelMeta[] = []
  const drlgPortLevels: number[] = []
  for (const row of tables.levels.rows) {
    if (cell(tables.levels, row, 'DrlgType') !== '3') continue
    const id = Number(cell(tables.levels, row, 'Id'))
    const name = cell(tables.levels, row, 'Name')
    const act = Number(cell(tables.levels, row, 'Act')) + 1
    // Act I outdoor levels come from the DRLG port (src/game/drlg); generateWilderness throws for them.
    if (act === 1) {
      drlgPortLevels.push(id)
      continue
    }
    const typeId = cell(tables.levels, row, 'LevelType')
    const typeRow = tables.lvltypes.rows.find(r => cell(tables.lvltypes, r, 'Id') === typeId)
    const levelTypeName = typeRow ? cell(tables.lvltypes, typeRow, 'Name') : ''
    const sizeX = Number(cell(tables.levels, row, 'SizeX'))
    const sizeY = Number(cell(tables.levels, row, 'SizeY'))
    const subType = Number(cell(tables.levels, row, 'SubType'))
    const subShrine = Number(cell(tables.levels, row, 'SubShrine'))
    const subTheme = Number(cell(tables.levels, row, 'SubTheme'))
    const isProcedural = !PRESET_WILDERNESS_LEVELS.has(id)

    wildernessLevels.push({
      id,
      name,
      act,
      levelTypeName,
      sizeX,
      sizeY,
      subType,
      subShrine,
      subTheme,
      isProcedural,
    })
  }

  console.log(`Discovered ${wildernessLevels.length} legacy-generator outdoor wilderness levels across Acts 2..5:`)
  console.log(`- Procedural outdoor levels: ${wildernessLevels.filter(l => l.isProcedural).length}`)
  console.log(`- Preset outdoor levels:     ${wildernessLevels.filter(l => !l.isProcedural).length}`)
  console.log(`(Act I outdoor levels ${drlgPortLevels.join(', ')} are the DRLG port's; see tests/drlg-act1-*.test.ts)\n`)

  const seeds50 = generate50Seeds()
  console.log(`Generated 50 distinct test seeds (includes 3 master seeds, 7 edge/boundary seeds, 40 random seeds).`)
  console.log(`Seed sample: [${seeds50.slice(0, 6).map(s => '0x' + s.toString(16)).join(', ')} ... (${seeds50.length} total)]\n`)

  let totalAssertions = 0
  let passedAssertions = 0
  let failedAssertions = 0
  const failureList: string[] = []

  function check(condition: boolean, description: string): void {
    totalAssertions += 1
    if (condition) {
      passedAssertions += 1
    } else {
      failedAssertions += 1
      failureList.push(description)
      console.error(`❌ FAILED: ${description}`)
    }
  }

  // ---------------------------------------------------------------------------
  // TEST 1 & 2: Seed Sensitivity & Determinism across 50 seeds for every legacy-generator level
  // ---------------------------------------------------------------------------
  console.log('--- [Test 1 & 2] 50-Seed Sensitivity & Deterministic Re-run Invariance ---')
  console.log(`Testing all ${wildernessLevels.length} wilderness levels across 50 distinct seeds...\n`)

  for (const level of wildernessLevels) {
    const pieces = await getWildernessPieces(level.levelTypeName)
    const subs = await getSubstitutions(level.subType)
    const shrineSubs = await getSubstitutions(level.subShrine)

    const seedToDigest = new Map<number, string>()
    const digests: string[] = []

    for (const seed of seeds50) {
      const req = {
        levelId: level.id,
        levelName: level.name,
        levelTypeName: level.levelTypeName,
        sizeX: level.sizeX,
        sizeY: level.sizeY,
        subType: level.subType,
        subTheme: Math.max(0, level.subTheme),
        seed,
        pieces,
        substitutions: subs,
        shrineSubstitutions: shrineSubs,
      }

      // Run 1
      const run1 = generateWilderness(req)
      const digest1 = canonicalHash(run1.level)

      // Run 2 (Determinism Verification)
      const run2 = generateWilderness(req)
      const digest2 = canonicalHash(run2.level)

      check(
        digest1 === digest2,
        `Level ${level.id} (${level.name}) seed 0x${seed.toString(16)} non-deterministic: ${digest1} !== ${digest2}`
      )

      seedToDigest.set(seed, digest1)
      digests.push(digest1)
    }

    const uniqueDigests = new Set(digests)

    if (level.isProcedural) {
      // Assertion 3: Zero collision across different seeds for procedural outdoor levels
      const collisionCount = digests.length - uniqueDigests.size
      check(
        collisionCount === 0,
        `Level ${level.id} (${level.name}) had ${collisionCount} hash collisions across 50 distinct seeds (${uniqueDigests.size}/50 unique)`
      )

      console.log(
        `  Act ${level.act} Level ${String(level.id).padStart(3)} | ${level.name.padEnd(25)} | ` +
        `50/50 unique (${uniqueDigests.size} distinct hashes) | 100% Deterministic (50/50 pairs matched)`
      )
    } else {
      // Preset level: determinism holds, hashes are consistent
      console.log(
        `  Act ${level.act} Level ${String(level.id).padStart(3)} | ${level.name.padEnd(25)} | ` +
        `[PRESET] ${uniqueDigests.size} variant(s) | 100% Deterministic (50/50 pairs matched)`
      )
    }
  }

  const elapsedSec = ((Date.now() - startTime) / 1000).toFixed(2)
  console.log('\n======================================================================')
  console.log(`📊 STRESS TEST SUMMARY (Completed in ${elapsedSec}s)`)
  console.log('======================================================================')
  console.log(`Total Assertions Executed: ${totalAssertions}`)
  console.log(`Passed Assertions:         ${passedAssertions}`)
  console.log(`Failed Assertions:         ${failedAssertions}`)

  if (failedAssertions > 0) {
    console.error('\n❌ FAILURES DETECTED:')
    for (const f of failureList) {
      console.error(`  - ${f}`)
    }
    process.exit(1)
  }

  const proceduralCount = wildernessLevels.filter(l => l.isProcedural).length
  console.log('\n✅ ALL 3 EMPIRICAL INVARIANTS SATISFIED WITHOUT EXCEPTION:')
  console.log(`1. Seed sensitivity: ${seeds50.length} distinct random seeds tested across all ${wildernessLevels.length} legacy-generator outdoor levels.`)
  console.log(`2. Determinism: ${wildernessLevels.length * seeds50.length} duplicate generation pairs produced 100% identical FNV-1a digests.`)
  console.log(`3. Zero collision: ${proceduralCount}/${proceduralCount} procedural levels produced ${seeds50.length}/${seeds50.length} unique digests (0 collisions).`)
  console.log('======================================================================\n')
}

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