/*
    *    Copyright 2010-2023 the original author or authors.
    *
    *    Licensed under the Apache License, Version 2.0 (the "License");
    *    you may not use this file except in compliance with the License.
    *    You may obtain a copy of the License at
    *
    *       https://www.apache.org/licenses/LICENSE-2.0
    *
   *    Unless required by applicable law or agreed to in writing, software
   *    distributed under the License is distributed on an "AS IS" BASIS,
   *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *    See the License for the specific language governing permissions and
   *    limitations under the License.
   */
  package org.apache.ibatis.migration;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.Reader;
  import java.math.BigDecimal;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  import java.util.Properties;
  
  import org.apache.ibatis.migration.utils.Util;
  
  public class FileMigrationLoader implements MigrationLoader {
    protected final File scriptsDir;
  
    protected final String charset;
  
    protected final Properties variables;
  
    public FileMigrationLoader(File scriptsDir, String charset, Properties variables) {
      this.scriptsDir = scriptsDir;
      this.charset = charset;
      this.variables = variables;
    }
  
    @Override
    public List<Change> getMigrations() {
      List<Change> migrations = new ArrayList<>();
      if (scriptsDir.isDirectory()) {
        String[] filenames = scriptsDir.list();
        if (filenames == null) {
          throw new MigrationException(scriptsDir + " does not exist.");
        }
        Arrays.sort(filenames);
        for (String filename : filenames) {
          if (filename.endsWith(".sql") && !isSpecialFile(filename)) {
            Change change = parseChangeFromFilename(filename);
            migrations.add(change);
          }
        }
      }
      return migrations;
    }
  
    protected boolean isSpecialFile(String filename) {
      return "bootstrap.sql".equals(filename) || "onabort.sql".equals(filename);
    }
  
    protected Change parseChangeFromFilename(String filename) {
      try {
        Change change = new Change();
        int lastIndexOfDot = filename.lastIndexOf('.');
        String[] parts = filename.substring(0, lastIndexOfDot).split("_");
        change.setId(new BigDecimal(parts[0]));
        StringBuilder builder = new StringBuilder();
        for (int i = 1; i < parts.length; i++) {
          if (i > 1) {
            builder.append(" ");
          }
          builder.append(parts[i]);
        }
        change.setDescription(builder.toString());
        change.setFilename(filename);
        return change;
      } catch (Exception e) {
        throw new MigrationException("Error parsing change from file.  Cause: " + e, e);
      }
    }
  
    @Override
    public Reader getScriptReader(Change change, boolean undo) {
      try {
        return new MigrationReader(Util.file(scriptsDir, change.getFilename()), charset, undo, variables);
      } catch (IOException e) {
        throw new MigrationException("Error reading " + change.getFilename(), e);
      }
    }
  
    @Override
    public Reader getBootstrapReader() {
      String fileName = "bootstrap.sql";
      return getSoleScriptReader(fileName);
    }
 
   @Override
   public Reader getOnAbortReader() {
     String fileName = "onabort.sql";
     return getSoleScriptReader(fileName);
   }
 
   protected Reader getSoleScriptReader(String fileName) {
     try {
       File scriptFile = Util.file(scriptsDir, fileName);
       if (scriptFile.exists()) {
         return new MigrationReader(scriptFile, charset, false, variables);
       }
       return null;
     } catch (IOException e) {
       throw new MigrationException("Error reading " + fileName, e);
     }
   }
 }