vChewing-macOS/Packages/vChewing_LangModelAssembly/Sources/LangModelAssembly/LMConsolidator.swift

// (c) 2021 and onwards The vChewing Project (MIT-NTL License).
// ====================
// This code is released under the MIT license (SPDX-License-Identifier: MIT)
// ... with NTL restriction stating that:
// No trademark license is granted to use the trade names, trademarks, service
// marks, or product names of Contributor, except as required to fulfill notice
// requirements defined in MIT License.

import Foundation
import LineReader
import Shared

extension vChewingLM {
  public enum LMConsolidator {
    public static let kPragmaHeader = "# 𝙵𝙾𝚁𝙼𝙰𝚃 𝚘𝚛𝚐.𝚊𝚝𝚎𝚕𝚒𝚎𝚛𝙸𝚗𝚖𝚞.𝚟𝚌𝚑𝚎𝚠𝚒𝚗𝚐.𝚞𝚜𝚎𝚛𝙻𝚊𝚗𝚐𝚞𝚊𝚐𝚎𝙼𝚘𝚍𝚎𝚕𝙳𝚊𝚝𝚊.𝚏𝚘𝚛𝚖𝚊𝚝𝚝𝚎𝚍"

    /// 檢查給定檔案的標頭是否正常。
    /// - Parameter path: 給定檔案路徑。
    /// - Returns: 結果正常則為真，其餘為假。
    public static func checkPragma(path: String) -> Bool {
      if FileManager.default.fileExists(atPath: path) {
        let fileHandle = FileHandle(forReadingAtPath: path)!
        do {
          let lineReader = try LineReader(file: fileHandle)
          for strLine in lineReader {  // 不需要 i=0，因為第一遍迴圈就出結果。
            if strLine != kPragmaHeader {
              vCLog("Header Mismatch, Starting In-Place Consolidation.")
              return false
            } else {
              vCLog("Header Verification Succeeded: \(strLine).")
              return true
            }
          }
        } catch {
          vCLog("Header Verification Failed: File Access Error.")
          return false
        }
      }
      vCLog("Header Verification Failed: File Missing.")
      return false
    }

    /// 檢查檔案是否以空行結尾，如果缺失則補充之。
    /// - Parameter path: 給定檔案路徑。
    /// - Returns: 結果正常或修復順利則為真，其餘為假。
    @discardableResult public static func fixEOF(path: String) -> Bool {
      let urlPath = URL(fileURLWithPath: path)
      if FileManager.default.fileExists(atPath: path) {
        var strIncoming = ""
        do {
          strIncoming += try String(contentsOf: urlPath, encoding: .utf8)
          /// 注意：Swift 版 LMConsolidator 並未在此安排對 EOF 的去重複工序。
          /// 但這個函式執行完之後往往就會 consolidate() 整理格式，所以不會有差。
          if !strIncoming.hasSuffix("\n") {
            vCLog("EOF Fix Necessity Confirmed, Start Fixing.")
            if let writeFile = FileHandle(forUpdatingAtPath: path),
              let endl = "\n".data(using: .utf8)
            {
              writeFile.seekToEndOfFile()
              writeFile.write(endl)
              writeFile.closeFile()
            } else {
              return false
            }
          }
        } catch {
          vCLog("EOF Fix Failed w/ File: \(path)")
          vCLog("EOF Fix Failed w/ Error: \(error).")
          return false
        }
        vCLog("EOF Successfully Ensured (with possible autofixes performed).")
        return true
      }
      vCLog("EOF Fix Failed: File Missing at \(path).")
      return false
    }

    /// 統整給定的檔案的格式。
    /// - Parameters:
    ///   - path: 給定檔案路徑。
    ///   - shouldCheckPragma: 是否在檔案標頭完好無損的情況下略過對格式的整理。
    /// - Returns: 若整理順利或無須整理，則為真；反之為假。
    @discardableResult public static func consolidate(path: String, pragma shouldCheckPragma: Bool) -> Bool {
      let pragmaResult = checkPragma(path: path)
      if shouldCheckPragma {
        if pragmaResult {
          return true
        }
      }

      let urlPath = URL(fileURLWithPath: path)
      if FileManager.default.fileExists(atPath: path) {
        var strProcessed = ""
        do {
          strProcessed += try String(contentsOf: urlPath, encoding: .utf8)

          // Step 1: Consolidating formats per line.
          // -------
          // CJKWhiteSpace (\x{3000}) to ASCII Space
          // NonBreakWhiteSpace (\x{A0}) to ASCII Space
          // Tab to ASCII Space
          // 統整連續空格為一個 ASCII 空格
          strProcessed.regReplace(pattern: #"( +|　+| +|\t+)+"#, replaceWith: " ")
          // 去除行尾行首空格
          strProcessed.regReplace(pattern: #"(^ | $)"#, replaceWith: "")
          strProcessed.regReplace(pattern: #"(\n | \n)"#, replaceWith: "\n")
          // CR & FF to LF, 且去除重複行
          strProcessed.regReplace(pattern: #"(\f+|\r+|\n+)+"#, replaceWith: "\n")
          if strProcessed.prefix(1) == " " {  // 去除檔案開頭空格
            strProcessed.removeFirst()
          }
          if strProcessed.suffix(1) == " " {  // 去除檔案結尾空格
            strProcessed.removeLast()
          }

          // Step 2: Add Formatted Pragma, the Sorted Header:
          if !pragmaResult {
            strProcessed = kPragmaHeader + "\n" + strProcessed  // Add Sorted Header
          }

          // Step 3: Deduplication.
          let arrData = strProcessed.split(separator: "\n")
          // 下面兩行的 reversed 是首尾顛倒，免得破壞最新的 override 資訊。
          let arrDataDeduplicated = Array(NSOrderedSet(array: arrData.reversed()).array as! [String])
          strProcessed = arrDataDeduplicated.reversed().joined(separator: "\n") + "\n"

          // Step 4: Remove duplicated newlines at the end of the file.
          strProcessed.regReplace(pattern: #"\n+"#, replaceWith: "\n")

          // Step 5: Write consolidated file contents.
          try strProcessed.write(to: urlPath, atomically: false, encoding: .utf8)

        } catch {
          vCLog("Consolidation Failed w/ File: \(path)")
          vCLog("Consolidation Failed w/ Error: \(error).")
          return false
        }
        vCLog("Either Consolidation Successful Or No-Need-To-Consolidate.")
        return true
      }
      vCLog("Consolidation Failed: File Missing at \(path).")
      return false
    }
  }
}

// MARK: - String Extension

extension String {
  fileprivate mutating func regReplace(pattern: String, replaceWith: String = "") {
    // Ref: https://stackoverflow.com/a/40993403/4162914 && https://stackoverflow.com/a/71291137/4162914
    do {
      let regex = try NSRegularExpression(
        pattern: pattern, options: [.caseInsensitive, .anchorsMatchLines]
      )
      let range = NSRange(startIndex..., in: self)
      self = regex.stringByReplacingMatches(
        in: self, options: [], range: range, withTemplate: replaceWith
      )
    } catch { return }
  }
}