/**
 * Generates src/game/drlg/drlg-ids.ts from D2MOO's DataTbls/LevelsIds.h (the LvlPrest, LvlSub and
 * LvlTypes enums), so the DRLG port uses exactly the ids D2MOO compiles against.
 *
 * D2MOO is read from D2MOO_SRC (default ~/tmp/D2MOO) and must be at the pinned commit.
 *
 * Usage: npx tsx scripts/gen-drlg-ids.ts
 */
import { execFileSync } from 'node:child_process'
import { readFileSync, writeFileSync } from 'node:fs'
import { homedir } from 'node:os'
import { join, resolve } from 'node:path'

const PINNED_COMMIT = '5596f5cb6c5251a0a07c6637d26458b06099d516'
const d2mooSrc = resolve(process.env.D2MOO_SRC ?? join(homedir(), 'tmp', 'D2MOO'))
const commit = execFileSync('git', ['-C', d2mooSrc, 'rev-parse', 'HEAD'], { encoding: 'utf8' }).trim()
if (commit !== PINNED_COMMIT) {
  throw new Error(`${d2mooSrc} is at ${commit}, expected ${PINNED_COMMIT}`)
}

const header = readFileSync(join(d2mooSrc, 'source/D2Common/include/DataTbls/LevelsIds.h'), 'latin1')

function parseEnum(name: string): [string, number][] {
  const match = new RegExp(`enum\\s+${name}\\s*\\{([\\s\\S]*?)\\};`).exec(header)
  if (!match) throw new Error(`enum ${name} not found`)
  const body = match[1]!
  if (/^\s*#/m.test(body)) throw new Error(`enum ${name} has preprocessor directives; handle them explicitly`)
  const entries: [string, number][] = []
  let value = -1
  for (const raw of body.replace(/\/\*[\s\S]*?\*\//g, '').split(',')) {
    const item = raw.replace(/\/\/.*$/gm, '').trim()
    if (!item) continue
    const eq = /^(\w+)\s*=\s*(.+)$/.exec(item)
    if (eq) {
      const literal = eq[2]!.trim()
      if (!/^(0x[0-9a-fA-F]+|\d+)$/.test(literal)) throw new Error(`${name}: unsupported initialiser ${item}`)
      value = Number(literal)
      entries.push([eq[1]!, value])
    } else {
      if (!/^\w+$/.test(item)) throw new Error(`${name}: unsupported entry ${item}`)
      value += 1
      entries.push([item, value])
    }
  }
  return entries
}

const sections: [string, string][] = [
  ['D2C_LvlPrestIds', 'LvlPrest.txt row ids (DataTbls/LevelsIds.h D2C_LvlPrestIds).'],
  ['D2C_LvlSubIds', 'LvlSub.txt types (DataTbls/LevelsIds.h D2C_LvlSubIds).'],
  ['D2C_LvlTypes', 'LvlTypes.txt ids (DataTbls/LevelsIds.h D2C_LvlTypes).'],
]

let out = `/**
 * GENERATED by scripts/gen-drlg-ids.ts from D2MOO source/D2Common/include/DataTbls/LevelsIds.h
 * (commit ${PINNED_COMMIT}, MIT License, Copyright (c) 2020-2025 The Phrozen Keep community).
 * Do not edit by hand.
 */
`
for (const [name, doc] of sections) {
  const entries = parseEnum(name)
  out += `\n// ${doc} ${entries.length} entries.\n`
  for (const [id, value] of entries) out += `export const ${id} = ${value}\n`
}

/** Values of `static const <type> <name>[..]... = { ... };` in a D2MOO source file, flattened. */
function extractArray(relPath: string, name: string, expectedLength: number): number[] {
  const source = readFileSync(join(d2mooSrc, relPath), 'latin1')
  const match = new RegExp(`static\\s+const\\s+\\w+\\s+${name}\\s*(?:\\[[^\\]]*\\])+\\s*=\\s*\\{([\\s\\S]*?)\\};`).exec(source)
  if (!match) throw new Error(`${relPath}: array ${name} not found`)
  const values = match[1]!
    .replace(/\/\/.*$/gm, '')
    .replace(/[{}]/g, ',')
    .split(',')
    .map(s => s.trim())
    .filter(s => s.length > 0)
    .map(s => {
      if (!/^(0x[0-9a-fA-F]+|\d+)$/.test(s)) throw new Error(`${relPath}: ${name}: unsupported literal ${s}`)
      return Number(s)
    })
  if (values.length !== expectedLength) {
    throw new Error(`${relPath}: ${name} has ${values.length} values, expected ${expectedLength}`)
  }
  return values
}

const arrays: [string, string, string, number, string][] = [
  ['source/D2Common/src/Drlg/DrlgPreset.cpp', 'dword_6FDE1180', 'gObjPresetToObjectId', 5 * 150,
    'DRLGPRESET_GetObjectIndexFromObjPreset (D2Common.0x6FD859E0): [nAct * 150 + nUnitId].'],
  ['source/D2Common/src/Drlg/DrlgPreset.cpp', 'nTileTypeMappingTable', 'gTileTypeMappingTable', 42,
    'DRLGPRESET_MapTileType (D2Common.0x6FD88850): DS1 version < 7 tile types.'],
  ['source/D2Common/src/Drlg/DrlgOutdoors.cpp', 'byte_6FDCF958', 'byte_6FDCF958', 256,
    'DRLG_OUTDOORS_GenerateDirtPath (D2Common.0x6FD7EFE0): dirt-path neighbourhood -> tile sequence.'],
]
for (const [relPath, name, exportName, length, doc] of arrays) {
  const values = extractArray(relPath, name, length)
  out += `\n// ${doc}\n// ${relPath}: ${name}\nexport const ${exportName}: readonly number[] = [\n`
  for (let i = 0; i < values.length; i += 25) out += `  ${values.slice(i, i + 25).join(', ')},\n`
  out += ']\n'
}

const target = resolve('src/game/drlg/drlg-ids.ts')
writeFileSync(target, out)
console.log(`wrote ${target}`)