// Based on https://github.com/rhashimoto/wa-sqlite/blob/master/src/FacadeVFS.js

/* eslint-disable unicorn/prefer-code-point */
/* eslint-disable @typescript-eslint/no-unused-vars */
/* eslint-disable prefer-arrow/prefer-arrow-functions */
// eslint-disable-next-line @typescript-eslint/ban-ts-comment
// @ts-nocheck
import * as VFS from '@livestore/wa-sqlite/src/VFS.js'

const AsyncFunction = Object.getPrototypeOf(async () => {}).constructor

export class FacadeVFS extends VFS.Base {
  /**
   * @param {string} name
   * @param {object} module
   */
  constructor(name, module) {
    super(name, module)
  }

  /**
   * Override to indicate which methods are asynchronous.
   * @param {string} methodName
   * @returns {boolean}
   */
  hasAsyncMethod(methodName) {
    // The input argument is a string like "xOpen", so convert to "jOpen".
    // Then check if the method exists and is async.
    const jMethodName = `j${methodName.slice(1)}`
    return this[jMethodName] instanceof AsyncFunction
  }

  /**
   * Return the filename for a file id for use by mixins.
   * @param {number} pFile
   * @returns {string}
   */
  getFilename(pFile) {
    throw new Error('unimplemented')
  }

  /**
   * @param {string?} filename
   * @param {number} pFile
   * @param {number} flags
   * @param {DataView} pOutFlags
   * @returns {number|Promise<number>}
   */
  jOpen(filename, pFile, flags, pOutFlags): number {
    return VFS.SQLITE_CANTOPEN
  }

  /**
   * @param {string} filename
   * @param {number} syncDir
   * @returns {number|Promise<number>}
   */
  jDelete(filename, syncDir): number {
    return VFS.SQLITE_OK
  }

  /**
   * @param {string} filename
   * @param {number} flags
   * @param {DataView} pResOut
   * @returns {number|Promise<number>}
   */
  jAccess(filename, flags, pResOut): number {
    return VFS.SQLITE_OK
  }

  /**
   * @param {string} filename
   * @param {Uint8Array} zOut
   * @returns {number|Promise<number>}
   */
  jFullPathname(filename, zOut): number {
    // Copy the filename to the output buffer.
    const { read, written } = new TextEncoder().encodeInto(filename, zOut)
    if (read < filename.length) return VFS.SQLITE_IOERR
    if (written >= zOut.length) return VFS.SQLITE_IOERR
    zOut[written] = 0
    return VFS.SQLITE_OK
  }

  /**
   * @param {Uint8Array} zBuf
   * @returns {number|Promise<number>}
   */
  jGetLastError(zBuf) {
    return VFS.SQLITE_OK
  }

  /**
   * @param {number} pFile
   * @returns {number|Promise<number>}
   */
  jClose(pFile): number {
    return VFS.SQLITE_OK
  }

  /**
   * @param {number} pFile
   * @param {Uint8Array} pData
   * @param {number} iOffset
   * @returns {number|Promise<number>}
   */
  jRead(pFile, pData, iOffset): number {
    pData.fill(0)
    return VFS.SQLITE_IOERR_SHORT_READ
  }

  /**
   * @param {number} pFile
   * @param {Uint8Array} pData
   * @param {number} iOffset
   * @returns {number|Promise<number>}
   */
  jWrite(pFile, pData, iOffset): number {
    return VFS.SQLITE_IOERR_WRITE
  }

  /**
   * @param {number} pFile
   * @param {number} size
   * @returns {number|Promise<number>}
   */
  jTruncate(pFile, size): number {
    return VFS.SQLITE_OK
  }

  /**
   * @param {number} pFile
   * @param {number} flags
   * @returns {number|Promise<number>}
   */
  jSync(pFile, flags): number {
    return VFS.SQLITE_OK
  }

  /**
   * @param {number} pFile
   * @param {DataView} pSize
   * @returns {number|Promise<number>}
   */
  jFileSize(pFile, pSize): number {
    return VFS.SQLITE_OK
  }

  /**
   * @param {number} pFile
   * @param {number} lockType
   * @returns {number|Promise<number>}
   */
  jLock(pFile, lockType): number {
    return VFS.SQLITE_OK
  }

  /**
   * @param {number} pFile
   * @param {number} lockType
   * @returns {number|Promise<number>}
   */
  jUnlock(pFile, lockType): number {
    return VFS.SQLITE_OK
  }

  /**
   * @param {number} pFile
   * @param {DataView} pResOut
   * @returns {number|Promise<number>}
   */
  jCheckReservedLock(pFile, pResOut): number {
    pResOut.setInt32(0, 0, true)
    return VFS.SQLITE_OK
  }

  /**
   * @param {number} pFile
   * @param {number} op
   * @param {DataView} pArg
   * @returns {number|Promise<number>}
   */
  jFileControl(pFile, op, pArg): number {
    return VFS.SQLITE_NOTFOUND
  }

  /**
   * @param {number} pFile
   * @returns {number|Promise<number>}
   */
  jSectorSize(pFile): number {
    return super.xSectorSize(pFile)
  }

  /**
   * @param {number} pFile
   * @returns {number|Promise<number>}
   */
  jDeviceCharacteristics(pFile): number {
    return 0
  }

  /**
   * @param {number} pVfs
   * @param {number} zName
   * @param {number} pFile
   * @param {number} flags
   * @param {number} pOutFlags
   * @returns {number|Promise<number>}
   */
  xOpen(pVfs, zName, pFile, flags, pOutFlags): number {
    const filename = this.#decodeFilename(zName, flags)
    const pOutFlagsView = this.#makeTypedDataView('Int32', pOutFlags)
    this['log']?.('jOpen', filename, pFile, '0x' + flags.toString(16))
    return this.jOpen(filename, pFile, flags, pOutFlagsView)
  }

  /**
   * @param {number} pVfs
   * @param {number} zName
   * @param {number} syncDir
   * @returns {number|Promise<number>}
   */
  xDelete(pVfs, zName, syncDir) {
    const filename = this._module.UTF8ToString(zName)
    this['log']?.('jDelete', filename, syncDir)
    return this.jDelete(filename, syncDir)
  }

  /**
   * @param {number} pVfs
   * @param {number} zName
   * @param {number} flags
   * @param {number} pResOut
   * @returns {number|Promise<number>}
   */
  xAccess(pVfs, zName, flags, pResOut) {
    const filename = this._module.UTF8ToString(zName)
    const pResOutView = this.#makeTypedDataView('Int32', pResOut)
    this['log']?.('jAccess', filename, flags)
    return this.jAccess(filename, flags, pResOutView)
  }

  /**
   * @param {number} pVfs
   * @param {number} zName
   * @param {number} nOut
   * @param {number} zOut
   * @returns {number|Promise<number>}
   */
  xFullPathname(pVfs, zName, nOut, zOut) {
    const filename = this._module.UTF8ToString(zName)
    const zOutArray = this._module.HEAPU8.subarray(zOut, zOut + nOut)
    this['log']?.('jFullPathname', filename, nOut)
    return this.jFullPathname(filename, zOutArray)
  }

  /**
   * @param {number} pVfs
   * @param {number} nBuf
   * @param {number} zBuf
   * @returns {number|Promise<number>}
   */
  xGetLastError(pVfs, nBuf, zBuf) {
    const zBufArray = this._module.HEAPU8.subarray(zBuf, zBuf + nBuf)
    this['log']?.('jGetLastError', nBuf)
    return this.jGetLastError(zBufArray)
  }

  /**
   * @param {number} pFile
   * @returns {number|Promise<number>}
   */
  xClose(pFile) {
    this['log']?.('jClose', pFile)
    return this.jClose(pFile)
  }

  /**
   * @param {number} pFile
   * @param {number} pData
   * @param {number} iAmt
   * @param {number} iOffsetLo
   * @param {number} iOffsetHi
   * @returns {number|Promise<number>}
   */
  xRead(pFile, pData, iAmt, iOffsetLo, iOffsetHi) {
    const pDataArray = this.#makeDataArray(pData, iAmt)
    const iOffset = delegalize(iOffsetLo, iOffsetHi)
    this['log']?.('jRead', pFile, iAmt, iOffset)
    return this.jRead(pFile, pDataArray, iOffset)
  }

  /**
   * @param {number} pFile
   * @param {number} pData
   * @param {number} iAmt
   * @param {number} iOffsetLo
   * @param {number} iOffsetHi
   * @returns {number|Promise<number>}
   */
  xWrite(pFile, pData, iAmt, iOffsetLo, iOffsetHi) {
    const pDataArray = this.#makeDataArray(pData, iAmt)
    const iOffset = delegalize(iOffsetLo, iOffsetHi)
    this['log']?.('jWrite', pFile, pDataArray, iOffset)
    return this.jWrite(pFile, pDataArray, iOffset)
  }

  /**
   * @param {number} pFile
   * @param {number} sizeLo
   * @param {number} sizeHi
   * @returns {number|Promise<number>}
   */
  xTruncate(pFile, sizeLo, sizeHi) {
    const size = delegalize(sizeLo, sizeHi)
    this['log']?.('jTruncate', pFile, size)
    return this.jTruncate(pFile, size)
  }

  /**
   * @param {number} pFile
   * @param {number} flags
   * @returns {number|Promise<number>}
   */
  xSync(pFile, flags) {
    this['log']?.('jSync', pFile, flags)
    return this.jSync(pFile, flags)
  }

  /**
   *
   * @param {number} pFile
   * @param {number} pSize
   * @returns {number|Promise<number>}
   */
  xFileSize(pFile, pSize) {
    const pSizeView = this.#makeTypedDataView('BigInt64', pSize)
    this['log']?.('jFileSize', pFile)
    return this.jFileSize(pFile, pSizeView)
  }

  /**
   * @param {number} pFile
   * @param {number} lockType
   * @returns {number|Promise<number>}
   */
  xLock(pFile, lockType) {
    this['log']?.('jLock', pFile, lockType)
    return this.jLock(pFile, lockType)
  }

  /**
   * @param {number} pFile
   * @param {number} lockType
   * @returns {number|Promise<number>}
   */
  xUnlock(pFile, lockType) {
    this['log']?.('jUnlock', pFile, lockType)
    return this.jUnlock(pFile, lockType)
  }

  /**
   * @param {number} pFile
   * @param {number} pResOut
   * @returns {number|Promise<number>}
   */
  xCheckReservedLock(pFile, pResOut) {
    const pResOutView = this.#makeTypedDataView('Int32', pResOut)
    this['log']?.('jCheckReservedLock', pFile)
    return this.jCheckReservedLock(pFile, pResOutView)
  }

  /**
   * @param {number} pFile
   * @param {number} op
   * @param {number} pArg
   * @returns {number|Promise<number>}
   */
  xFileControl(pFile, op, pArg) {
    const pArgView = new DataView(this._module.HEAPU8.buffer, this._module.HEAPU8.byteOffset + pArg)
    this['log']?.('jFileControl', pFile, op, pArgView)
    return this.jFileControl(pFile, op, pArgView)
  }

  /**
   * @param {number} pFile
   * @returns {number|Promise<number>}
   */
  xSectorSize(pFile) {
    this['log']?.('jSectorSize', pFile)
    return this.jSectorSize(pFile)
  }

  /**
   * @param {number} pFile
   * @returns {number|Promise<number>}
   */
  xDeviceCharacteristics(pFile) {
    this['log']?.('jDeviceCharacteristics', pFile)
    return this.jDeviceCharacteristics(pFile)
  }

  /**
   * Wrapped DataView for pointer arguments.
   * Pointers to a single value are passed using DataView. A Proxy
   * wrapper prevents use of incorrect type or endianness.
   * @param {'Int32'|'BigInt64'} type
   * @param {number} byteOffset
   * @returns {DataView}
   */
  #makeTypedDataView(type, byteOffset) {
    const byteLength = type === 'Int32' ? 4 : 8
    const getter = `get${type}`
    const setter = `set${type}`
    const makeDataView = () =>
      new DataView(this._module.HEAPU8.buffer, this._module.HEAPU8.byteOffset + byteOffset, byteLength)
    let dataView = makeDataView()
    return new Proxy(dataView, {
      get(_, prop) {
        if (dataView.buffer.byteLength === 0) {
          // WebAssembly memory resize detached the buffer.
          dataView = makeDataView()
        }
        if (prop === getter) {
          return function (byteOffset, littleEndian) {
            if (!littleEndian) throw new Error('must be little endian')
            return dataView[prop](byteOffset, littleEndian)
          }
        }
        if (prop === setter) {
          return function (byteOffset, value, littleEndian) {
            if (!littleEndian) throw new Error('must be little endian')
            return dataView[prop](byteOffset, value, littleEndian)
          }
        }
        if (typeof prop === 'string' && /^(get)|(set)/.test(prop)) {
          throw new Error('invalid type')
        }
        const result = dataView[prop]
        return typeof result === 'function' ? result.bind(dataView) : result
      },
    })
  }

  /**
   * @param {number} byteOffset
   * @param {number} byteLength
   */
  #makeDataArray(byteOffset, byteLength) {
    let target = this._module.HEAPU8.subarray(byteOffset, byteOffset + byteLength)
    return new Proxy(target, {
      get: (_, prop, receiver) => {
        if (target.buffer.byteLength === 0) {
          // WebAssembly memory resize detached the buffer.
          target = this._module.HEAPU8.subarray(byteOffset, byteOffset + byteLength)
        }
        const result = target[prop]
        return typeof result === 'function' ? result.bind(target) : result
      },
    })
  }

  #decodeFilename(zName, flags) {
    if (flags & VFS.SQLITE_OPEN_URI) {
      // The first null-terminated string is the URI path. Subsequent
      // strings are query parameter keys and values.
      // https://www.sqlite.org/c3ref/open.html#urifilenamesinsqlite3open
      let pName = zName
      let state = 1
      const charCodes = []
      while (state) {
        const charCode = this._module.HEAPU8[pName++]
        if (charCode) {
          charCodes.push(charCode)
        } else {
          if (!this._module.HEAPU8[pName]) state = null
          switch (state) {
            case 1: {
              // path
              charCodes.push('?'.charCodeAt(0))
              state = 2
              break
            }
            case 2: {
              // key
              charCodes.push('='.charCodeAt(0))
              state = 3
              break
            }
            case 3: {
              // value
              charCodes.push('&'.charCodeAt(0))
              state = 2
              break
            }
          }
        }
      }
      return new TextDecoder().decode(new Uint8Array(charCodes))
    }
    return zName ? this._module.UTF8ToString(zName) : null
  }
}
// Emscripten "legalizes" 64-bit integer arguments by passing them as
// two 32-bit signed integers.
function delegalize(lo32, hi32) {
  return hi32 * 0x1_00_00_00_00 + lo32 + (lo32 < 0 ? 2 ** 32 : 0)
}