package com.tyron.resolver;

import java.math.BigInteger;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Properties;

/**
 * Generic implementation of version comparison. Features:
 *
 * <ul>
 *   <li>mixing of '<code>-</code>' (hyphen) and '<code>.</code>' (dot) separators,
 *   <li>transition between characters and digits also constitutes a separator: <code>
 *       1.0alpha1 =&gt; [1, 0, alpha, 1]</code>
 *   <li>unlimited number of version components,
 *   <li>version components in the text can be digits or strings,
 *   <li>strings are checked for well-known qualifiers and the qualifier ordering is used for
 *       version ordering. Well-known qualifiers (case insensitive) are:
 *       <ul>
 *         <li><code>alpha</code> or <code>a</code>
 *         <li><code>beta</code> or <code>b</code>
 *         <li><code>milestone</code> or <code>m</code>
 *         <li><code>rc</code> or <code>cr</code>
 *         <li><code>snapshot</code>
 *         <li><code>(the empty string)</code> or <code>ga</code> or <code>final</code>
 *         <li><code>sp</code>
 *       </ul>
 *       Unknown qualifiers are considered after known qualifiers, with lexical order (always case
 *       insensitive),
 *   <li>a hyphen usually precedes a qualifier, and is always less important than something preceded
 *       with a dot.
 * </ul>
 *
 * @see <a href="https://cwiki.apache.org/confluence/display/MAVENOLD/Versioning">"Versioning" on
 *     Maven Wiki</a>
 * @author <a href="mailto:kenney@apache.org">Kenney Westerhof</a>
 * @author <a href="mailto:hboutemy@apache.org">Hervé Boutemy</a>
 */
public class ComparableVersion implements Comparable<ComparableVersion> {
  private static final int MAX_INTITEM_LENGTH = 9;

  private static final int MAX_LONGITEM_LENGTH = 18;

  private String value;

  private String canonical;

  private ListItem items;

  private interface Item {
    int INT_ITEM = 3;
    int LONG_ITEM = 4;
    int BIGINTEGER_ITEM = 0;
    int STRING_ITEM = 1;
    int LIST_ITEM = 2;

    int compareTo(Item item);

    int getType();

    boolean isNull();
  }

  /** Represents a numeric item in the version item list that can be represented with an int. */
  private static class IntItem implements Item {
    private final int value;

    public static final IntItem ZERO = new IntItem();

    private IntItem() {
      this.value = 0;
    }

    IntItem(String str) {
      this.value = Integer.parseInt(str);
    }

    @Override
    public int getType() {
      return INT_ITEM;
    }

    @Override
    public boolean isNull() {
      return value == 0;
    }

    @Override
    public int compareTo(Item item) {
      if (item == null) {
        return (value == 0) ? 0 : 1; // 1.0 == 1, 1.1 > 1
      }

      switch (item.getType()) {
        case INT_ITEM:
          int itemValue = ((IntItem) item).value;
          return Integer.compare(value, itemValue);
        case LONG_ITEM:
        case BIGINTEGER_ITEM:
          return -1;

        case STRING_ITEM:
          return 1; // 1.1 > 1-sp

        case LIST_ITEM:
          return 1; // 1.1 > 1-1

        default:
          throw new IllegalStateException("invalid item: " + item.getClass());
      }
    }

    @Override
    public boolean equals(Object o) {
      if (this == o) {
        return true;
      }
      if (o == null || getClass() != o.getClass()) {
        return false;
      }

      IntItem intItem = (IntItem) o;

      return value == intItem.value;
    }

    @Override
    public int hashCode() {
      return value;
    }

    @Override
    public String toString() {
      return Integer.toString(value);
    }
  }

  /** Represents a numeric item in the version item list that can be represented with a long. */
  private static class LongItem implements Item {
    private final long value;

    LongItem(String str) {
      this.value = Long.parseLong(str);
    }

    @Override
    public int getType() {
      return LONG_ITEM;
    }

    @Override
    public boolean isNull() {
      return value == 0;
    }

    @Override
    public int compareTo(Item item) {
      if (item == null) {
        return (value == 0) ? 0 : 1; // 1.0 == 1, 1.1 > 1
      }

      switch (item.getType()) {
        case INT_ITEM:
          return 1;
        case LONG_ITEM:
          long itemValue = ((LongItem) item).value;
          return Long.compare(value, itemValue);
        case BIGINTEGER_ITEM:
          return -1;

        case STRING_ITEM:
          return 1; // 1.1 > 1-sp

        case LIST_ITEM:
          return 1; // 1.1 > 1-1

        default:
          throw new IllegalStateException("invalid item: " + item.getClass());
      }
    }

    @Override
    public boolean equals(Object o) {
      if (this == o) {
        return true;
      }
      if (o == null || getClass() != o.getClass()) {
        return false;
      }

      LongItem longItem = (LongItem) o;

      return value == longItem.value;
    }

    @Override
    public int hashCode() {
      return (int) (value ^ (value >>> 32));
    }

    @Override
    public String toString() {
      return Long.toString(value);
    }
  }

  /** Represents a numeric item in the version item list. */
  private static class BigIntegerItem implements Item {
    private final BigInteger value;

    BigIntegerItem(String str) {
      this.value = new BigInteger(str);
    }

    @Override
    public int getType() {
      return BIGINTEGER_ITEM;
    }

    @Override
    public boolean isNull() {
      return BigInteger.ZERO.equals(value);
    }

    @Override
    public int compareTo(Item item) {
      if (item == null) {
        return BigInteger.ZERO.equals(value) ? 0 : 1; // 1.0 == 1, 1.1 > 1
      }

      switch (item.getType()) {
        case INT_ITEM:
        case LONG_ITEM:
          return 1;

        case BIGINTEGER_ITEM:
          return value.compareTo(((BigIntegerItem) item).value);

        case STRING_ITEM:
          return 1; // 1.1 > 1-sp

        case LIST_ITEM:
          return 1; // 1.1 > 1-1

        default:
          throw new IllegalStateException("invalid item: " + item.getClass());
      }
    }

    @Override
    public boolean equals(Object o) {
      if (this == o) {
        return true;
      }
      if (o == null || getClass() != o.getClass()) {
        return false;
      }

      BigIntegerItem that = (BigIntegerItem) o;

      return value.equals(that.value);
    }

    @Override
    public int hashCode() {
      return value.hashCode();
    }

    public String toString() {
      return value.toString();
    }
  }

  /** Represents a string in the version item list, usually a qualifier. */
  private static class StringItem implements Item {
    private static final List<String> QUALIFIERS =
        Arrays.asList("alpha", "beta", "milestone", "rc", "snapshot", "", "sp");

    private static final Properties ALIASES = new Properties();

    static {
      ALIASES.put("ga", "");
      ALIASES.put("final", "");
      ALIASES.put("release", "");
      ALIASES.put("cr", "rc");
    }

    /**
     * A comparable value for the empty-string qualifier. This one is used to determine if a given
     * qualifier makes the version older than one without a qualifier, or more recent.
     */
    private static final String RELEASE_VERSION_INDEX = String.valueOf(QUALIFIERS.indexOf(""));

    private final String value;

    StringItem(String value, boolean followedByDigit) {
      if (followedByDigit && value.length() == 1) {
        // a1 = alpha-1, b1 = beta-1, m1 = milestone-1
        switch (value.charAt(0)) {
          case 'a':
            value = "alpha";
            break;
          case 'b':
            value = "beta";
            break;
          case 'm':
            value = "milestone";
            break;
          default:
        }
      }
      this.value = ALIASES.getProperty(value, value);
    }

    @Override
    public int getType() {
      return STRING_ITEM;
    }

    @Override
    public boolean isNull() {
      return (comparableQualifier(value).compareTo(RELEASE_VERSION_INDEX) == 0);
    }

    /**
     * Returns a comparable value for a qualifier.
     *
     * <p>This method takes into account the ordering of known qualifiers then unknown qualifiers
     * with lexical ordering.
     *
     * <p>just returning an Integer with the index here is faster, but requires a lot of
     * if/then/else to check for -1 or QUALIFIERS.size and then resort to lexical ordering. Most
     * comparisons are decided by the first character, so this is still fast. If more characters are
     * needed then it requires a lexical sort anyway.
     *
     * @param qualifier
     * @return an equivalent value that can be used with lexical comparison
     */
    public static String comparableQualifier(String qualifier) {
      int i = QUALIFIERS.indexOf(qualifier);

      return i == -1 ? (QUALIFIERS.size() + "-" + qualifier) : String.valueOf(i);
    }

    @Override
    public int compareTo(Item item) {
      if (item == null) {
        // 1-rc < 1, 1-ga > 1
        return comparableQualifier(value).compareTo(RELEASE_VERSION_INDEX);
      }
      switch (item.getType()) {
        case INT_ITEM:
        case LONG_ITEM:
        case BIGINTEGER_ITEM:
          return -1; // 1.any < 1.1 ?

        case STRING_ITEM:
          return comparableQualifier(value)
              .compareTo(comparableQualifier(((StringItem) item).value));

        case LIST_ITEM:
          return -1; // 1.any < 1-1

        default:
          throw new IllegalStateException("invalid item: " + item.getClass());
      }
    }

    @Override
    public boolean equals(Object o) {
      if (this == o) {
        return true;
      }
      if (o == null || getClass() != o.getClass()) {
        return false;
      }

      StringItem that = (StringItem) o;

      return value.equals(that.value);
    }

    @Override
    public int hashCode() {
      return value.hashCode();
    }

    public String toString() {
      return value;
    }
  }

  /**
   * Represents a version list item. This class is used both for the global item list and for
   * sub-lists (which start with '-(number)' in the version specification).
   */
  private static class ListItem extends ArrayList<Item> implements Item {
    @Override
    public int getType() {
      return LIST_ITEM;
    }

    @Override
    public boolean isNull() {
      return (size() == 0);
    }

    void normalize() {
      for (int i = size() - 1; i >= 0; i--) {
        Item lastItem = get(i);

        if (lastItem.isNull()) {
          // remove null trailing items: 0, "", empty list
          remove(i);
        } else if (!(lastItem instanceof ListItem)) {
          break;
        }
      }
    }

    @Override
    public int compareTo(Item item) {
      if (item == null) {
        if (size() == 0) {
          return 0; // 1-0 = 1- (normalize) = 1
        }
        // Compare the entire list of items with null - not just the first one, MNG-6964
        for (Item i : this) {
          int result = i.compareTo(null);
          if (result != 0) {
            return result;
          }
        }
        return 0;
      }
      switch (item.getType()) {
        case INT_ITEM:
        case LONG_ITEM:
        case BIGINTEGER_ITEM:
          return -1; // 1-1 < 1.0.x

        case STRING_ITEM:
          return 1; // 1-1 > 1-sp

        case LIST_ITEM:
          Iterator<Item> left = iterator();
          Iterator<Item> right = ((ListItem) item).iterator();

          while (left.hasNext() || right.hasNext()) {
            Item l = left.hasNext() ? left.next() : null;
            Item r = right.hasNext() ? right.next() : null;

            // if this is shorter, then invert the compare and mul with -1
            int result = l == null ? (r == null ? 0 : -1 * r.compareTo(l)) : l.compareTo(r);

            if (result != 0) {
              return result;
            }
          }

          return 0;

        default:
          throw new IllegalStateException("invalid item: " + item.getClass());
      }
    }

    @Override
    public String toString() {
      StringBuilder buffer = new StringBuilder();
      for (Item item : this) {
        if (buffer.length() > 0) {
          buffer.append((item instanceof ListItem) ? '-' : '.');
        }
        buffer.append(item);
      }
      return buffer.toString();
    }

    /** Return the contents in the same format that is used when you call toString() on a List. */
    private String toListString() {
      StringBuilder buffer = new StringBuilder();
      buffer.append("[");
      for (Item item : this) {
        if (buffer.length() > 1) {
          buffer.append(", ");
        }
        if (item instanceof ListItem) {
          buffer.append(((ListItem) item).toListString());
        } else {
          buffer.append(item);
        }
      }
      buffer.append("]");
      return buffer.toString();
    }
  }

  public ComparableVersion(String version) {
    parseVersion(version);
  }

  @SuppressWarnings("checkstyle:innerassignment")
  public final void parseVersion(String version) {
    this.value = version;

    items = new ListItem();

    version = version.toLowerCase(Locale.ENGLISH);

    ListItem list = items;

    Deque<Item> stack = new ArrayDeque<>();
    stack.push(list);

    boolean isDigit = false;

    int startIndex = 0;

    for (int i = 0; i < version.length(); i++) {
      char c = version.charAt(i);

      if (c == '.') {
        if (i == startIndex) {
          list.add(IntItem.ZERO);
        } else {
          list.add(parseItem(isDigit, version.substring(startIndex, i)));
        }
        startIndex = i + 1;
      } else if (c == '-') {
        if (i == startIndex) {
          list.add(IntItem.ZERO);
        } else {
          list.add(parseItem(isDigit, version.substring(startIndex, i)));
        }
        startIndex = i + 1;

        list.add(list = new ListItem());
        stack.push(list);
      } else if (Character.isDigit(c)) {
        if (!isDigit && i > startIndex) {
          list.add(new StringItem(version.substring(startIndex, i), true));
          startIndex = i;

          list.add(list = new ListItem());
          stack.push(list);
        }

        isDigit = true;
      } else {
        if (isDigit && i > startIndex) {
          list.add(parseItem(true, version.substring(startIndex, i)));
          startIndex = i;

          list.add(list = new ListItem());
          stack.push(list);
        }

        isDigit = false;
      }
    }

    if (version.length() > startIndex) {
      list.add(parseItem(isDigit, version.substring(startIndex)));
    }

    while (!stack.isEmpty()) {
      list = (ListItem) stack.pop();
      list.normalize();
    }
  }

  private static Item parseItem(boolean isDigit, String buf) {
    if (isDigit) {
      buf = stripLeadingZeroes(buf);
      if (buf.length() <= MAX_INTITEM_LENGTH) {
        // lower than 2^31
        return new IntItem(buf);
      } else if (buf.length() <= MAX_LONGITEM_LENGTH) {
        // lower than 2^63
        return new LongItem(buf);
      }
      return new BigIntegerItem(buf);
    }
    return new StringItem(buf, false);
  }

  private static String stripLeadingZeroes(String buf) {
    if (buf == null || buf.isEmpty()) {
      return "0";
    }
    for (int i = 0; i < buf.length(); ++i) {
      char c = buf.charAt(i);
      if (c != '0') {
        return buf.substring(i);
      }
    }
    return buf;
  }

  @Override
  public int compareTo(ComparableVersion o) {
    return items.compareTo(o.items);
  }

  @Override
  public String toString() {
    return value;
  }

  public String getCanonical() {
    if (canonical == null) {
      canonical = items.toString();
    }
    return canonical;
  }

  @Override
  public boolean equals(Object o) {
    return (o instanceof ComparableVersion) && items.equals(((ComparableVersion) o).items);
  }

  @Override
  public int hashCode() {
    return items.hashCode();
  }

  // CHECKSTYLE_OFF: LineLength
  /**
   * Main to test version parsing and comparison.
   *
   * <p>To check how "1.2.7" compares to "1.2-SNAPSHOT", for example, you can issue
   *
   * <pre>
   * java -jar ${maven.repo.local}/org/apache/maven/maven-artifact/${maven.version}/maven-artifact-${maven.version}.jar "1.2.7" "1.2-SNAPSHOT"
   * </pre>
   *
   * command to command line. Result of given command will be something like this:
   *
   * <pre>
   * Display parameters as parsed by Maven (in canonical form) and comparison result:
   * 1. 1.2.7 == 1.2.7
   *    1.2.7 &gt; 1.2-SNAPSHOT
   * 2. 1.2-SNAPSHOT == 1.2-snapshot
   * </pre>
   *
   * @param args the version strings to parse and compare. You can pass arbitrary number of version
   *     strings and always two adjacent will be compared
   */
  // CHECKSTYLE_ON: LineLength
  public static void main(String... args) {
    System.out.println(
        "Display parameters as parsed by Maven (in canonical form and as a list of tokens) and"
            + " comparison result:");
    if (args.length == 0) {
      return;
    }

    ComparableVersion prev = null;
    int i = 1;
    for (String version : args) {
      ComparableVersion c = new ComparableVersion(version);

      if (prev != null) {
        int compare = prev.compareTo(c);
        System.out.println(
            "   "
                + prev.toString()
                + ' '
                + ((compare == 0) ? "==" : ((compare < 0) ? "<" : ">"))
                + ' '
                + version);
      }

      System.out.println(
          (i++)
              + ". "
              + version
              + " -> "
              + c.getCanonical()
              + "; tokens: "
              + c.items.toListString());

      prev = c;
    }
  }
}
