/**
 * Bake map assets out of the archives into web-native packs.
 *
 * The page can already read the real archives, but doing so costs it 38 MB and
 * ~11k range requests per visit (measured), because it decodes DS1/DT1/PL2 and
 * builds an atlas in the browser every time. This script moves all of that
 * offline: it walks the same code the page walks — `resolveLevel`, `decodeDs1`,
 * `decodeDt1`, `buildIsoMapScene`, `decodeDc6` — and writes the *result* as
 * indexed PNG tile pages plus one JSON scene per map. The page then decodes
 * nothing but PNG.
 *
 * Design decisions worth knowing:
 *
 * - **Indexed PNG, one palette per act.** Diablo II art is palette-indexed and
 *   each act ships its own `pal.pl2`; PNG colour type 3 carries both, so the
 *   browser's own decoder does the palette expansion on the GPU upload path.
 * - **Pages of at most 2048², hot frames first.** Frames used near the spawn go
 *   into the first page(s), so the page can paint after loading one or two PNGs
 *   instead of the whole map.
 * - **The scene JSON is the authority, not a re-derivation.** Draw lists are
 *   already in painter's order and the collision grid is exactly the one the
 *   live path produces; `scripts/verify-packs.ts` re-derives both from the MPQs
 *   and fails if they differ by a byte.
 *
 * Usage: node scripts/pack-act-assets.ts [archive-directory] [output-directory]
 */
import { mkdir, writeFile } from 'node:fs/promises'
import { createHash } from 'node:crypto'
import { join } from 'node:path'
import { MpqArchive } from '../src/mpq/archive.ts'
import { fileSource } from '../src/mpq/file-source.ts'
import { MountedArchives } from '../src/mpq/mount.ts'
import { cell, loadActTables, parseTable, resolveLevel, resolveLevelLibraries, tileMemberPath } from '../src/game/acts.ts'
import type { ActTables, LevelInfo, D2Table } from '../src/game/acts.ts'
import { decodeDs1 } from '../src/formats/ds1.ts'
import type { Ds1 } from '../src/formats/ds1.ts'
import { decodeDt1 } from '../src/formats/dt1.ts'
import type { Dt1 } from '../src/formats/dt1.ts'
import { decodePl2 } from '../src/formats/pl2.ts'
import { levelSeed, buildIsoMapScene, cellAt, findIsoSpawn, ORTHO_SUB_TILE_HEIGHT, ORTHO_SUB_TILE_WIDTH } from '../src/game/d2map.ts'
import type { IsoMapScene } from '../src/game/d2map.ts'
import { loadObjectsTable, resolveDs1Object, MONSTER_ROOT } from '../src/game/objects.ts'
import { decodeDcc } from '../src/formats/dcc.ts'
import { decodeDc6 } from '../src/formats/dc6.ts'
import type { SpriteFrame } from '../src/formats/sprite.ts'
import { generateMaze, classifyMazePieceName } from '../src/game/maze.ts'
import type { MazePiece, MazePieceKind } from '../src/game/maze.ts'
import { generateWilderness } from '../src/game/wilderness.ts'
import type { WildernessPiece, WildernessSubstitution } from '../src/game/wilderness.ts'
import { encodeIndexedPng } from './png.ts'

/**
 * Archive stack, in load order (later overrides earlier).
 *
 * `d2char.mpq` is mounted *first* so it sits at the bottom: it holds the object
 * and character art (`data\global\objects\…`) but no map data, and this order
 * keeps the map lookups resolving through `d2data` → `d2exp` → `Patch_D2` as the
 * game does.
 */
const MOUNTS = ['d2char.mpq', 'd2data.mpq', 'd2exp.mpq', 'Patch_D2.mpq'] as const
/** Atlas page side limit (both dimensions). */
const PAGE_SIZE = 2048
/** Cells around the spawn whose frames go into the first page. */
const HOT_RADIUS_CELLS = 8
/** Where object art lives. */
const OBJECT_PREFIX = 'data\\global\\objects\\'
/** Where monster and town-NPC art lives. */
/**
 * Mode directories tried in order when picking an object's art.
 *
 * Note what the object art actually *is*: under `data\global\objects` the
 * archives hold **1748 DCC and 1461 COF files against just 13 DC6**. Diablo II
 * draws objects with the same composite pipeline as characters — a COF that
 * lists layers and frames plus the DCC files behind them — so this packer
 * records each object's placement and its exact art members, and leaves the
 * pixels to the `COF`/`DCC` decoder that the character art also needs. Baking a
 * wrong file as if it were a DC6 would have produced silent garbage instead.
 */
const OBJECT_MODES = ['tr', 'nu', 's1', 's2', 's3'] as const

/**
 * The maps to bake, derived from `Levels.txt` rather than listed by hand.
 *
 * `DrlgType` picks the generator, exactly as the game does (documented in the
 * knowledge base and mirrored by OpenDiablo2):
 *
 * - **2 = preset area**: `LvlPrest` rows name fixed DS1 files, so the map is
 *   baked byte-for-byte — what `verify-packs.ts` diffs against the live decoder.
 * - **1 = random maze** / **3 = wilderness**: no fixed layout exists. Those come
 *   from the generators (`src/game/maze.ts`, `src/game/wilderness.ts`) driven by
 *   `LvlMaze`, `LvlSub` and the `LvlPrest` room pieces, and their packs are
 *   marked `approximation` because the engine's own placement is hardcoded.
 */
type LevelKind = 'preset' | 'maze' | 'wilderness'

/** One map to bake. */
interface LevelJob {
  readonly act: number
  readonly levelId: number
  readonly name: string
  readonly kind: LevelKind
  readonly slug: string
}

/** Filled in from `Levels.txt` once the tables are loaded. */
let LEVELS: readonly LevelJob[] = []

/**
 * Turn a level name into a stable, file-friendly slug.
 *
 * @param name - `Levels.txt` name, e.g. `Act 1 - Tristram`.
 * @returns the slug.
 */
function slugify(name: string): string {
  return name.toLowerCase().replace(/[^a-z0-9]+/g, '-').replace(/^-+|-+$/g, '')
}

/** One frame's placement inside a page. */
interface Placement {
  readonly page: number
  readonly x: number
  readonly y: number
  readonly width: number
  readonly height: number
}

/** One atlas page being packed. */
interface PackedPage {
  readonly pixels: Uint8Array
  frames: number
}

/** Frames, shelf-packed into pages of at most {@link PAGE_SIZE} squared. */
class PageBuilder {
  private readonly pages: PackedPage[] = []
  /** Palette the pages are encoded against. */
  private readonly palette: Uint8Array
  private cursorX = 0
  private shelfY = 0
  private shelfHeight = 0

  constructor(palette: Uint8Array) {
    this.palette = palette
  }

  /** Frames placed so far. */
  get placed(): number {
    return this.pages.reduce((sum, page) => sum + page.frames, 0)
  }

  /** The pages, with their used height. */
  get pageCount(): number {
    return this.pages.length
  }

  /**
   * Place one indexed frame, opening pages as needed.
   *
   * Shelves keep placement trivial and predictable; frames wider than a page are
   * clamped rather than rejected, because a tile bigger than 2048 px would be a
   * broken library, not a reason to lose the whole map.
   *
   * @param frame - width, height and palette indices.
   * @returns where the frame landed.
   */
  add(frame: { width: number; height: number; indices: Uint8Array }): Placement {
    const width = Math.max(1, Math.min(frame.width, PAGE_SIZE))
    const height = Math.max(1, Math.min(frame.height, PAGE_SIZE))
    if (this.cursorX + width > PAGE_SIZE) {
      this.shelfY += this.shelfHeight
      this.shelfHeight = 0
      this.cursorX = 0
    }
    if (this.pages.length === 0 || this.shelfY + height > PAGE_SIZE) {
      this.pages.push({ pixels: new Uint8Array(PAGE_SIZE * PAGE_SIZE), frames: 0 })
      this.shelfY = 0
      this.shelfHeight = 0
      this.cursorX = 0
    }
    const page = this.pages[this.pages.length - 1]!
    const placement: Placement = {
      page: this.pages.length - 1, x: this.cursorX, y: this.shelfY, width, height,
    }
    for (let row = 0; row < height; row += 1) {
      const from = row * frame.width
      const to = (this.shelfY + row) * PAGE_SIZE + this.cursorX
      page.pixels.set(frame.indices.subarray(from, from + width), to)
    }
    this.cursorX += width
    this.shelfHeight = Math.max(this.shelfHeight, height)
    page.frames += 1
    return placement
  }

  /**
   * Encode every page, trimming each to the rows it actually used.
   *
   * @param transparent - palette index to mark transparent.
   * @returns file-ready PNGs, in page order.
   */
  encode(transparent: number): { name: string; png: Uint8Array; width: number; height: number; frames: number }[] {
    return this.pages.map((page, index) => {
      const used = Math.max(1, this.usedHeight(page))
      const trimmed = new Uint8Array(PAGE_SIZE * used)
      for (let row = 0; row < used; row += 1) {
        trimmed.set(page.pixels.subarray(row * PAGE_SIZE, (row + 1) * PAGE_SIZE), row * PAGE_SIZE)
      }
      return {
        name: `tiles-${String(index)}.png`,
        png: encodeIndexedPng({
          width: PAGE_SIZE,
          height: used,
          pixels: trimmed,
          palette: this.palette,
          transparentIndex: transparent,
        }),
        width: PAGE_SIZE,
        height: used,
        frames: page.frames,
      }
    })
  }

  /**
   * Height of the last written row, for trimming.
   *
   * @param page - the page.
   * @returns the used height in rows.
   */
  private usedHeight(page: PackedPage): number {
    for (let row = PAGE_SIZE - 1; row >= 0; row -= 1) {
      const from = row * PAGE_SIZE
      for (let x = 0; x < PAGE_SIZE; x += 1) if (page.pixels[from + x] !== 0) return row + 1
    }
    return 1
  }
}

/**
 * FNV-1a over a frame's indexed pixels, so verification can compare content
 * without shipping the pixels twice.
 *
 * @param indices - palette indices.
 * @returns an 8-character hex digest.
 */
function frameHash(indices: Uint8Array): string {
  let hash = 0x811c9dc5
  for (const byte of indices) {
    hash ^= byte
    hash = Math.imul(hash, 0x01000193) >>> 0
  }
  return hash.toString(16).padStart(8, '0')
}

/**
 * Turn a DS1 member name into a file-friendly slug.
 *
 * @param member - full member path.
 * @returns the slug.
 */
function slugOf(member: string): string {
  const base = member.split('\\').pop() ?? member
  return base.replace(/\.ds1$/i, '').toLowerCase()
}

const [archiveDir = 'samples/d2', outDir = 'samples/d2-packs'] = process.argv.slice(2)

const archives = new MountedArchives()
for (const name of MOUNTS) {
  archives.add(name, await MpqArchive.open(await fileSource(join(archiveDir, name))))
}
const tables: ActTables = await loadActTables(archives)
const objectsTable = parseTable(await archives.read('data\\global\\excel\\objects.txt'))
/** Same table, through the typed loader the object resolution expects. */
const objectsTableTyped = await loadObjectsTable(archives)

/**
 * `MonPreset.txt` `Place` values grouped by act.
 *
 * The position within an act **is** the DS1 type-1 `id`, so this array must stay
 * dense: dropping a row would renumber every entry after it and silently hand
 * each NPC its neighbour's identity. Measured against the 1.13c drop there are
 * zero empty `Place` cells in all five acts, so the guard below never fires —
 * it exists to fail loudly rather than quietly misnumber if that ever changes.
 */
const presetPlaceByAct = new Map<string, string[]>()
for (const row of tables.monpreset.rows) {
  const act = cell(tables.monpreset, row, 'Act')
  const place = cell(tables.monpreset, row, 'Place')
  if (!place) {
    throw new Error(
      `MonPreset.txt act ${act} has an empty Place cell; the row index is the DS1 id, `
      + 'so skipping it would shift every later NPC onto the wrong monster',
    )
  }
  let list = presetPlaceByAct.get(act)
  if (list === undefined) {
    list = []
    presetPlaceByAct.set(act, list)
  }
  list.push(place)
}

/** `monstats.txt` rows indexed by `Id` (the column `MonPreset.Place` points at). */
const statsById = new Map<string, readonly string[]>()
for (const row of tables.monstats.rows) {
  const id = cell(tables.monstats, row, 'Id')
  if (id) statsById.set(id, row)
}

const monstersTable = {
  preset: tables.monpreset,
  stats: tables.monstats,
  presetPlaceByAct,
  statsById,
}

const allNames = await archives.listFiles()

{
  const jobs: LevelJob[] = []
  for (const row of tables.levels.rows) {
    const levelId = Number(cell(tables.levels, row, 'Id'))
    if (!Number.isFinite(levelId) || levelId === 0) continue
    const name = cell(tables.levels, row, 'Name')
    const drlg = Number(cell(tables.levels, row, 'DrlgType'))
    const act = Number(cell(tables.levels, row, 'Act')) + 1
    let kind: LevelKind | null = null
    if (drlg === 2) kind = 'preset'
    else if (drlg === 1) kind = 'maze'
    else if (drlg === 3) kind = 'wilderness'
    if (kind === null) continue
    jobs.push({ act, levelId, name, kind, slug: `${String(levelId)}-${slugify(name)}` })
  }
  LEVELS = jobs
}

/**
 * Decoded DT1 libraries, kept across levels.
 *
 * A hundred-plus levels share a few dozen level types, so decoding each library
 * once instead of once per level turns the bake from repeated work into one pass.
 */
/**
 * Decoded DT1 libraries, keyed by member name.
 *
 * Bounded on purpose: every level keeps its DT1 block bitmaps alive (each library
 * decodes to tens of MB of palette indices), and an unbounded cache held 4+ GB by
 * the time the bake reached act 5. Sixteen libraries is more than any single
 * level type uses, so a level never re-decodes mid-level, and the memory ceiling
 * stays flat across a whole 62-map bake.
 */
const libraryCache = new Map<string, Dt1>()
/** Most DT1 libraries to keep decoded at once. */
const LIBRARY_CACHE_LIMIT = 16

/**
 * Decode a DT1 library, cached by member name.
 *
 * @param member - archive member name.
 * @returns the decoded library.
 */
async function libraryOf(member: string): Promise<Dt1> {
  const cached = libraryCache.get(member)
  if (cached !== undefined) return cached
  const decoded = decodeDt1(await archives.read(member))
  libraryCache.set(member, decoded)
  if (libraryCache.size > LIBRARY_CACHE_LIMIT) {
    // `Map` iterates in insertion order, so the first key is the oldest entry.
    const oldest = libraryCache.keys().next().value
    if (oldest !== undefined && oldest !== member) libraryCache.delete(oldest)
  }
  return decoded
}

/** Objects.txt lookup by Id, built once. */
const objectById = new Map<number, { name: string; token: string; hp: number }>()
for (const row of objectsTable.rows) {
  const id = Number(cell(objectsTable, row, 'Id'))
  if (!Number.isFinite(id)) continue
  objectById.set(id, {
    name: cell(objectsTable, row, 'Name'),
    token: cell(objectsTable, row, 'Token').toUpperCase(),
    hp: Number(cell(objectsTable, row, 'HitPoints') || '0'),
  })
}

/** Object members grouped by token and mode, built once. */
const objectMembers = new Map<string, Map<string, string[]>>()
const monsterMembers = new Map<string, Map<string, string[]>>()
for (const name of allNames) {
  const isObj = name.toLowerCase().startsWith(OBJECT_PREFIX.toLowerCase())
  const isMon = name.toLowerCase().startsWith(MONSTER_ROOT.toLowerCase())
  if (!isObj && !isMon) continue
  // Derive the length; a hand-counted magic number here was off by one (22 vs
  // the real 21), which sliced the first letter off every monster token and
  // silently broke all NPC art lookups.
  const prefixLen = isObj ? OBJECT_PREFIX.length : MONSTER_ROOT.length
  const rest = name.slice(prefixLen).split('\\')
  if (rest.length < 3) continue
  const token = (rest[0] ?? '').toUpperCase()
  const mode = (rest[1] ?? '').toLowerCase()
  const map = isObj ? objectMembers : monsterMembers
  if (!map.has(token)) map.set(token, new Map())
  const modes = map.get(token)!
  if (!modes.has(mode)) modes.set(mode, [])
  modes.get(mode)!.push(name)
}

const COMPONENT_PREFERENCE = ['tr', 'hd', 's1', 's2', 's3', 's4', 's5', 's6', 's7', 's8', 'lg', 'ra', 'la', 'rh', 'lh', 'sh'] as const

function compRank(path: string): number {
  const parts = path.toLowerCase().split('\\')
  const comp = parts[4] ?? ''
  const idx = COMPONENT_PREFERENCE.indexOf(comp as (typeof COMPONENT_PREFERENCE)[number])
  return idx >= 0 ? idx : 99
}

/**
 * Pick the member that stands in for an object's art.
 *
 * A token ships many variants (lit/unlit, per-mode, per-weapon-class); the pack
 * is static art, so one deterministic pick is recorded — mode order first, then
 * component preference (body layer 'tr' first), then file format (DCC before DC6)
 * — and COF definition files are filtered out since they are compositing metadata,
 * not sprites.
 *
 * @param token - object token from the lookup table.
 * @param modeToken - animation mode token the engine places the object in (`NU`/`OP`/…).
 * @returns the member name and how many candidates there were.
 */
function pickObjectMember(token: string, modeToken: string, baseIsMonsters = false): { member: string; candidates: number } | null {
  const map = baseIsMonsters ? monsterMembers : objectMembers
  const dirs = map.get(token.toUpperCase())
  if (dirs === undefined) return null
  const all = [...dirs.values()].flat().filter(name => {
    const lower = name.toLowerCase()
    return lower.endsWith('.dcc') || lower.endsWith('.dc6')
  })
  const candidates = all.length
  if (candidates === 0) return null
  const wanted = modeToken.trim().toLowerCase() === '' ? 'nu' : modeToken.trim().toLowerCase()
  const order = [wanted, ...OBJECT_MODES.map(mode => mode.toLowerCase()).filter(mode => mode !== wanted)]
  for (const mode of order) {
    const files = all
      .filter(name => {
        const base = (name.split('\\').pop() ?? '').toLowerCase()
        return base.includes(mode) || (mode !== 'nu' && base.includes(`lit${mode}`))
      })
      .sort((a, b) => {
        const aDcc = a.toLowerCase().endsWith('.dcc') ? 0 : 1
        const bDcc = b.toLowerCase().endsWith('.dcc') ? 0 : 1
        if (aDcc !== bDcc) return aDcc - bDcc
        const aRank = compRank(a)
        const bRank = compRank(b)
        if (aRank !== bRank) return aRank - bRank
        return a.localeCompare(b)
      })
    if (files.length > 0) return { member: files[0]!, candidates }
  }
  // No file carries the mode token: fall back to any member, deterministically.
  const fallback = [...all].sort((a, b) => {
    const aDcc = a.toLowerCase().endsWith('.dcc') ? 0 : 1
    const bDcc = b.toLowerCase().endsWith('.dcc') ? 0 : 1
    if (aDcc !== bDcc) return aDcc - bDcc
    const aRank = compRank(a)
    const bRank = compRank(b)
    if (aRank !== bRank) return aRank - bRank
    return a.localeCompare(b)
  })[0]
  return fallback === undefined ? null : { member: fallback, candidates }
}

/** Cache decoded member frames across levels so each unique member is decoded once. */
const decodedMemberCache = new Map<string, { frame: SpriteFrame; offsetX: number; offsetY: number }>()

const lvlmaze = parseTable(await archives.read('data\\global\\excel\\LvlMaze.txt'))
const lvlsub = parseTable(await archives.read('data\\global\\excel\\LvlSub.txt'))

/** The level type row for a level row. */
function levelType(levelRow: readonly string[]): { id: string; name: string } {
  const id = cell(tables.levels, levelRow, 'LevelType')
  const row = tables.lvltypes.rows.find(candidate => cell(tables.lvltypes, candidate, 'Id') === id)
  return { id, name: row === undefined ? '' : cell(tables.lvltypes, row, 'Name') }
}

/** The `LvlMaze` row for a level, by id then by name. */
function mazeRow(levelId: number, levelName: string): readonly string[] | undefined {
  return lvlmaze.rows.find(row => Number(cell(lvlmaze, row, 'Level')) === levelId)
    ?? lvlmaze.rows.find(row => cell(lvlmaze, row, 'Name') === levelName)
}

const ds1Cache = new Map<string, Ds1>()

async function loadDs1(member: string): Promise<Ds1> {
  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(tileMemberPath(value)))
  }
  return levels
}

function themeValues(table: D2Table, row: readonly string[], prefix: string): number[] {
  const values: number[] = []
  for (let index = 0; index < 5; index += 1) values.push(Number(cell(table, row, `${prefix}${String(index)}`)) || 0)
  return values
}

const WILDERNESS_PIECE_FAMILIES: Readonly<Record<string, readonly string[]>> = {
  'Act 1 - Wilderness': [
    'Act 1 - Wild',
    'Act 1 - Corral Fill',
    'Act 1 - Bivouac',
    'Act 1 - Pond',
    'Act 1 - Swamp Fill',
    'Act 1 - Stone Fill',
  ],
  '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'],
}

const mazePiecesCache = new Map<string, Promise<MazePiece[]>>()
function getMazePieces(levelTypeName: string, levelTypeId: string): Promise<MazePiece[]> {
  void levelTypeId
  const cached = mazePiecesCache.get(levelTypeName)
  if (cached !== undefined) return cached
  const promise = (async () => {
    const pieces: MazePiece[] = []
    for (const row of tables.lvlprest.rows) {
      if (cell(tables.lvlprest, row, 'LevelId') !== '0' && cell(tables.lvlprest, row, 'LevelId') !== '') continue
      const name = cell(tables.lvlprest, row, 'Name')
      const classified = classifyMazePieceName(name, levelTypeName)
      if (classified === null) continue
      const levels = await rowDs1s(tables.lvlprest, row)
      if (levels.length === 0) continue
      pieces.push({ name, kind: classified.kind satisfies MazePieceKind, sides: classified.sides, levels })
    }
    return pieces
  })()
  mazePiecesCache.set(levelTypeName, promise)
  return promise
}

const wildernessPiecesCache = new Map<string, Promise<WildernessPiece[]>>()
function getWildernessPieces(levelTypeName: string): Promise<WildernessPiece[]> {
  const cached = wildernessPiecesCache.get(levelTypeName)
  if (cached !== undefined) return cached
  const promise = (async () => {
    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
      pieces.push({ name, levels, border: /border|cliff/i.test(name) })
    }
    return pieces
  })()
  wildernessPiecesCache.set(levelTypeName, promise)
  return promise
}

const substitutionsCache = new Map<number, Promise<WildernessSubstitution[]>>()
function getSubstitutions(type: number): Promise<WildernessSubstitution[]> {
  if (type < 0) return Promise.resolve([])
  const cached = substitutionsCache.get(type)
  if (cached !== undefined) return cached
  const promise = (async () => {
    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(tileMemberPath(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: themeValues(lvlsub, row, 'Prob'),
        trials: themeValues(lvlsub, row, 'Trials'),
        max: themeValues(lvlsub, row, 'Max'),
        levels,
      })
    }
    return rows
  })()
  substitutionsCache.set(type, promise)
  return promise
}

const paletteCache = new Map<string, Uint8Array>()
async function getPalette(paletteName: string): Promise<Uint8Array> {
  const cached = paletteCache.get(paletteName)
  if (cached !== undefined) return cached
  const pl2 = decodePl2(await archives.read(paletteName))
  paletteCache.set(paletteName, pl2.rgb)
  return pl2.rgb
}

const index: Record<string, unknown> = {
  version: 1,
  generated: new Date().toISOString(),
  archiveDir,
  pageSize: PAGE_SIZE,
  palettes: {} as Record<string, number[]>,
  levels: [] as unknown[],
}

for (let act = 1; act <= 5; act += 1) {
  const pal = await getPalette(`data\\global\\palette\\act${String(act)}\\pal.pl2`)
  ;(index.palettes as Record<string, number[]>)[`act${String(act)}`] = [...pal]
}

let totalPngBytes = 0
let totalLevels = 0
let skippedArtlessSpawns = 0
let skippedMissingArtSpawns = 0

async function bakeDs1Variant(
  entry: LevelJob,
  levelName: string,
  palette: Uint8Array,
  paletteName: string,
  dt1Names: readonly string[],
  libraries: Dt1[],
  level: Ds1,
  ds1Name: string,
  label: string,
  seed: number,
): Promise<void> {
  const scene: IsoMapScene = buildIsoMapScene(level, libraries, seed)
  const spawn = findIsoSpawn(scene)
  const dir = join(outDir, `act${String(entry.act)}`, label)

  // Frames used near the spawn load first; everything else follows.
  const hot = new Set<number>()
  if (spawn !== null) {
    const spawnCell = cellAt(scene, spawn.x, spawn.y)
    for (const draw of scene.floors) {
      const distance = Math.abs(draw.cellX - spawnCell.x) + Math.abs(draw.cellY - spawnCell.y)
      if (distance <= HOT_RADIUS_CELLS) hot.add(draw.frameIndex)
    }
    for (const draw of scene.walls) {
      const distance = Math.abs(draw.cellX - spawnCell.x) + Math.abs(draw.cellY - spawnCell.y)
      if (distance <= HOT_RADIUS_CELLS) hot.add(draw.frameIndex)
    }
  }

  const firstDrawAt = new Map<number, { x: number; y: number }>()
  for (const draw of [...scene.floors, ...scene.walls]) {
    if (!firstDrawAt.has(draw.frameIndex)) firstDrawAt.set(draw.frameIndex, { x: draw.x, y: draw.y })
  }
  const bandOf = (frameIndex: number): number => {
    const at = firstDrawAt.get(frameIndex)
    if (at === undefined) return Number.MAX_SAFE_INTEGER
    return Math.floor(at.y / 512) * 4096 + Math.floor(at.x / 768)
  }
  const order = scene.frames.map((_, at) => at).sort((a, b) => {
    const ha = hot.has(a) ? 0 : 1
    const hb = hot.has(b) ? 0 : 1
    if (ha !== hb) return ha - hb
    const ba = bandOf(a)
    const bb = bandOf(b)
    if (ba !== bb) return ba - bb
    const fa = scene.frames[a]!
    const fb = scene.frames[b]!
    return fb.width * fb.height - fa.width * fa.height
  })
  const pages = new PageBuilder(palette)
  const placementOf = new Map<number, Placement>()
  for (const frameIndex of order) {
    const frame = scene.frames[frameIndex]!
    placementOf.set(frameIndex, pages.add(frame))
  }
  const pageFiles = pages.encode(0)
  await mkdir(dir, { recursive: true })
  const sha = createHash('sha256')
  for (const page of pageFiles) {
    await writeFile(join(dir, page.name), page.png)
    sha.update(page.png)
    totalPngBytes += page.png.byteLength
  }

  const objectPages = new PageBuilder(palette)
  const objects: unknown[] = []
  const npcs: unknown[] = []
  const missingObjects: string[] = []
  let objectsWithArt = 0
  const placementByMember = new Map<string, { placement: Placement; offsetX: number; offsetY: number }>()

  for (const object of level.objects) {
    let resolved
    try {
      resolved = resolveDs1Object(objectsTableTyped, entry.act, object.type, object.id, monstersTable)
    } catch (err) {
      missingObjects.push((err as Error).message)
      continue
    }
    if (resolved.kind === 'monster') continue
    if (resolved.kind === 'npc' && object.type === 1 && resolved.artless) {
      skippedArtlessSpawns += 1
      continue
    }
    const row = resolved.row
    const pick = resolved.token === '' ? null : pickObjectMember(resolved.token, resolved.mode, resolved.kind === 'npc')
    if (pick === null && resolved.kind === 'npc' && object.type === 1) {
      skippedMissingArtSpawns += 1
      continue
    }
    const orthoX = (object.x - object.y) * ORTHO_SUB_TILE_WIDTH + scene.originX
    const orthoY = (object.x + object.y) * ORTHO_SUB_TILE_HEIGHT + scene.originY

    let objectFrame: {
      page: number
      x: number
      y: number
      width: number
      height: number
      offsetX: number
      offsetY: number
    } | null = null

    if (pick !== null) {
      let placed = placementByMember.get(pick.member)
      if (placed === undefined) {
        let art = decodedMemberCache.get(pick.member)
        if (art === undefined) {
          try {
            const bytes = await archives.read(pick.member)
            if (pick.member.toLowerCase().endsWith('.dc6')) {
              const sheet = decodeDc6(bytes)
              const group = sheet.groups[0]
              const f = group?.frames[0]
              if (f) {
                art = {
                  frame: f,
                  offsetX: -16 + f.offsetX,
                  offsetY: 16 + (f.offsetY - f.height + 1),
                }
              }
            } else {
              const dcc = decodeDcc(bytes)
              const dir = dcc.directions[0]
              const f = dir?.frames[0]
              if (f && dir) {
                art = {
                  frame: f.frame,
                  offsetX: -16 + dir.box.left,
                  offsetY: 16 + dir.box.top,
                }
              }
            }
            if (art) decodedMemberCache.set(pick.member, art)
          } catch (err) {
            console.warn(`failed to decode object member ${pick.member}: ${(err as Error).message}`)
          }
        }
        if (art) {
          const placement = objectPages.add(art.frame)
          placed = { placement, offsetX: art.offsetX, offsetY: art.offsetY }
          placementByMember.set(pick.member, placed)
        }
      }
      if (placed) {
        objectFrame = {
          page: placed.placement.page,
          x: placed.placement.x,
          y: placed.placement.y,
          width: placed.placement.width,
          height: placed.placement.height,
          offsetX: placed.offsetX,
          offsetY: placed.offsetY,
        }
      }
    }

    const list = resolved.kind === 'npc' ? npcs : objects
    list.push({
      id: object.id,
      type: object.type,
      name: resolved.name ?? row?.name ?? resolved.token,
      token: resolved.token,
      mode: resolved.mode === '' ? 'NU' : resolved.mode,
      // `objectsTxtId` is the Objects.txt row the table points at; -1 means the
      // engine picks the art straight from the table's token, with no row.
      objectsTxtId: resolved.entry?.objectsTxtId ?? -1,
      hp: row === null ? 0 : (objectById.get(row.id)?.hp ?? 0),
      member: pick === null ? null : pick.member,
      alternatives: pick === null ? 0 : pick.candidates,
      // Screen point of the object's sub-tile; the sprite anchor is applied
      // when a frame exists.
      x: Math.round(orthoX),
      y: Math.round(orthoY),
      depth: (object.x + object.y) / 5,
      frame: objectFrame,
    })
    if (pick !== null) objectsWithArt += 1
    else missingObjects.push(`${resolved.token === '' ? `id ${String(object.id)}` : resolved.token} (act ${String(entry.act)}) has no art members`)
  }

  const objectFiles = objectPages.encode(0)
  const shaObjects = createHash('sha256')
  for (const page of objectFiles) {
    const name = page.name.replace('tiles-', 'objects-')
    await writeFile(join(dir, name), page.png)
    shaObjects.update(page.png)
    totalPngBytes += page.png.byteLength
  }

  // Collision grid as runs, so the JSON stays small without a second format.
  const runs: number[][] = []
  let current = scene.blocked[0] ?? 0
  let count = 0
  for (const value of scene.blocked) {
    if (value === current) { count += 1; continue }
    runs.push([current, count])
    current = value
    count = 1
  }
  runs.push([current, count])

  const sceneJson = {
    version: 1,
    fidelity: entry.kind === 'preset' ? 'exact' : 'approximation',
    act: entry.act,
    levelId: entry.levelId,
    levelName,
    ds1: ds1Name,
    cellsX: scene.cellsX,
    cellsY: scene.cellsY,
    originX: scene.originX,
    originY: scene.originY,
    widthPx: scene.widthPx,
    heightPx: scene.heightPx,
    pageSize: PAGE_SIZE,
    pages: pageFiles.map(page => ({ file: page.name, width: page.width, height: page.height })),
    objectPages: objectFiles.map(page => ({ file: page.name.replace('tiles-', 'objects-'), width: page.width, height: page.height })),
    frames: scene.frames.map(frame => [frame.width, frame.height]),
    frameHash: scene.frames.map(frame => frameHash(frame.indices)),
    framePlacement: scene.frames.map((_, at) => {
      const place = placementOf.get(at)!
      return [place.page, place.x, place.y, place.width, place.height]
    }),
    floors: scene.floors.map(draw => [draw.frameIndex, draw.x, draw.y, draw.cellX, draw.cellY]),
    walls: scene.walls.map(draw => [draw.frameIndex, draw.x, draw.y, draw.cellX, draw.cellY]),
    roofs: scene.roofs.map(draw => [draw.frameIndex, draw.x, draw.y, draw.cellX, draw.cellY]),
    objects,
    npcs,
    collision: { width: scene.gridWidth, height: scene.gridHeight, runs },
    spawn: spawn === null ? null : [Math.round(spawn.x), Math.round(spawn.y)],
    stats: {
      floors: scene.floors.length,
      walls: scene.walls.length,
      roofs: scene.roofs.length,
      frames: scene.frames.length,
      missingTiles: scene.missingTiles,
      missingRefs: scene.missingRefs,
      walkable: 1 - [...scene.blocked].reduce((sum, value) => sum + value, 0) / scene.blocked.length,
      objects: objects.length,
      npcs: npcs.length,
      objectsWithArt,
      objectsUnresolved: missingObjects,
      objectsArtPending: (objects as any[]).filter(o => o.member !== null && o.frame === null).length,
      dt1Libraries: dt1Names.length,
    },
  }
  const sceneBytes = new TextEncoder().encode(JSON.stringify(sceneJson))
  await writeFile(join(dir, 'scene.json'), sceneBytes)
  const manifest = {
    level: levelName,
    act: entry.act,
    levelId: entry.levelId,
    ds1: ds1Name,
    dt1: dt1Names,
    palette: paletteName,
    sceneBytes: sceneBytes.byteLength,
    sceneSha256: createHash('sha256').update(sceneBytes).digest('hex'),
    tilePagesSha256: sha.digest('hex'),
    objectPagesSha256: shaObjects.digest('hex'),
    pngBytes: pageFiles.reduce((sum, page) => sum + page.png.byteLength, 0)
      + objectFiles.reduce((sum, page) => sum + page.png.byteLength, 0),
    sourceArchive: MOUNTS,
  }
  await writeFile(join(dir, 'manifest.json'), JSON.stringify(manifest, null, 1))
  ;(index.levels as unknown[]).push({
    act: entry.act,
    levelId: entry.levelId,
    kind: entry.kind,
    slug: entry.slug,
    label,
    levelName,
    ds1: ds1Name,
    path: `act${String(entry.act)}/${label}`,
    cells: `${String(scene.cellsX)}x${String(scene.cellsY)}`,
    frames: scene.frames.length,
    objects: objects.length,
    npcs: npcs.length,
    pages: pageFiles.length,
    objectPages: objectFiles.length,
    missingTiles: scene.missingTiles,
    bytes: manifest.pngBytes + sceneBytes.byteLength,
  })
  totalLevels += 1
  const bakedFramesCount = (objects as any[]).filter(o => o.frame !== null).length
  const pendingCount = (objects as any[]).filter(o => o.member !== null && o.frame === null).length
  console.log(
    `[${String(totalLevels).padStart(3)}] act${String(entry.act)}/${label.padEnd(35)} `
    + `${String(scene.cellsX)}x${String(scene.cellsY)} `
    + `${String(scene.frames.length).padStart(3)} 图块 → ${String(pageFiles.length)} 页 PNG `
    + `(${(manifest.pngBytes / 1024).toFixed(0)} KB) + scene.json ${(sceneBytes.byteLength / 1024).toFixed(0)} KB `
    + `· 对象 ${String(objects.length)}/${String(level.objects.length)}（已接帧：${String(bakedFramesCount)}，待解：${String(pendingCount)}）`
    + ` · 缺失瓦片 ${String(scene.missingTiles)}`,
  )
}

const filterLevel = process.env.FILTER_LEVEL

for (const entry of LEVELS) {
  if (filterLevel !== undefined && String(entry.levelId) !== filterLevel) continue

  const levelRow = tables.levels.rows.find(candidate => Number(cell(tables.levels, candidate, 'Id')) === entry.levelId)!
  const paletteIndex = Number(cell(tables.levels, levelRow, 'Pal'))
  const paletteName = `data\\global\\palette\\act${String(paletteIndex + 1)}\\pal.pl2`
  const palette = await getPalette(paletteName)

  if (entry.kind === 'preset') {
    const info: LevelInfo = resolveLevel(tables, entry.levelId, entry.act)
    const libraries: Dt1[] = []
    for (const name of info.dt1Names) libraries.push(await libraryOf(name))

    for (const ds1Name of info.ds1Names) {
      const level = await loadDs1(ds1Name)
      const label = `${entry.slug}-${slugOf(ds1Name)}`
      await bakeDs1Variant(entry, info.levelName, palette, info.paletteName, info.dt1Names, libraries, level, ds1Name, label, levelSeed(ds1Name))
    }
  } else if (entry.kind === 'maze') {
    const type = levelType(levelRow)
    const row = mazeRow(entry.levelId, entry.name)
    if (row === undefined) {
      console.warn(`skipping maze ${entry.name}: no LvlMaze.txt row`)
      continue
    }
    const sectionX = Number(cell(lvlmaze, row, 'SizeX'))
    const sectionY = Number(cell(lvlmaze, row, 'SizeY'))
    const minRooms = Number(cell(lvlmaze, row, 'Rooms'))
    const merge = Number(cell(lvlmaze, row, 'Merge'))
    const pieces = await getMazePieces(type.name, type.id)
    if (pieces.length === 0) {
      console.warn(`skipping maze ${entry.name}: no maze pieces`)
      continue
    }
    const libInfo = resolveLevelLibraries(tables, entry.levelId)
    const libraries: Dt1[] = []
    for (const name of libInfo.dt1Names) libraries.push(await libraryOf(name))

    for (let v = 1; v <= 3; v += 1) {
      const seed = 0x5eed_0000 + entry.levelId * 10 + v
      const label = `${entry.slug}-var${v}`
      try {
        const result = generateMaze({
          levelId: entry.levelId,
          levelName: entry.name,
          levelTypeName: type.name,
          sectionSize: sectionX,
          sectionHeight: sectionY,
          minRooms,
          merge,
          seed,
          pieces,
        })
        await bakeDs1Variant(entry, entry.name, palette, paletteName, libInfo.dt1Names, libraries, result.level, `generated:${label}`, label, seed)
      } catch (err) {
        console.error(`failed to bake maze ${label}: ${(err as Error).message}`)
      }
    }
  } else if (entry.kind === 'wilderness') {
    const type = levelType(levelRow)
    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 getWildernessPieces(type.name)
    if (pieces.length === 0) {
      console.warn(`skipping wilderness ${entry.name}: no wilderness pieces`)
      continue
    }
    const rows = await getSubstitutions(subType)
    const shrineRows = await getSubstitutions(subShrine)
    const libInfo = resolveLevelLibraries(tables, entry.levelId)
    const libraries: Dt1[] = []
    for (const name of libInfo.dt1Names) libraries.push(await libraryOf(name))

    for (let v = 1; v <= 3; v += 1) {
      const seed = 0x5eed_1000 + entry.levelId * 10 + v
      const label = `${entry.slug}-var${v}`
      try {
        const result = generateWilderness({
          levelId: entry.levelId,
          levelName: entry.name,
          levelTypeName: type.name,
          sizeX,
          sizeY,
          subType,
          subTheme: Math.max(0, subTheme),
          seed,
          pieces,
          substitutions: rows,
          shrineSubstitutions: shrineRows,
        })
        await bakeDs1Variant(entry, entry.name, palette, paletteName, libInfo.dt1Names, libraries, result.level, `generated:${label}`, label, seed)
      } catch (err) {
        console.error(`failed to bake wilderness ${label}: ${(err as Error).message}`)
      }
    }
  }
}

await mkdir(outDir, { recursive: true })
await writeFile(join(outDir, 'index.json'), JSON.stringify(index, null, 1))
console.log(`\n打包完成：${String(totalLevels)} 张地图，PNG 合计 ${(totalPngBytes / 1048576).toFixed(1)} MB，输出 ${outDir}`)
console.log(`Skipped artless spawns: ${skippedArtlessSpawns}, Skipped no-art NPCs: ${skippedMissingArtSpawns}`)