/*----------------------------------------------------------------------------*/
/* Copyright (c) 2018-2019 FIRST. All Rights Reserved.                        */
/* Open Source Software - may be modified and shared by FRC teams. The code   */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project.                                                               */
/*----------------------------------------------------------------------------*/

package frc4388.utility;

import java.awt.Color;

import java.io.BufferedReader;
import java.io.IOException;
import java.lang.invoke.MethodHandleProxies;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.nio.file.Files;
import java.nio.file.Path;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.IntFunction;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class CSV<R> {
  private static final Pattern SANITIZER = Pattern.compile("[^$\\w,]");

  private final Supplier<R> generator;
  private final IntFunction<R[]> arrayGenerator;
  private final Map<String, BiConsumer<R, String>> setters;

  /**
   * A binary string operator to be applied to the entire header of the CSV.
   */
  protected String headerSanitizer(final String header) {
    return SANITIZER.matcher(header).replaceAll("");
  }

  /**
   * A binary string operator to be applied to each name in the header of the CSV.
   */
  protected String nameProcessor(final String name) {
    return Character.toLowerCase(name.charAt(0)) + name.substring(1);
  }

  /**
   * Creates a new {@code CSV} instance and prepares for populating the fields of objects created by
   * the given generator. Private fields and fields of primitive types are not supported.
   * @param generator a parameterless supplier which produces a new object with any number of fields
   *                  corresponding to header names from a CSV file. The first character of the names
   *                  from the header in the CSV file will be made lowercase and invalid characters
   *                  will be removed to match Java naming conventions.
   * @see #read(Path)
   */
  @SuppressWarnings("unchecked")
  public CSV(final Supplier<R> generator) {
    final Class<?> clazz = generator.get().getClass();
    final Map<Class<?>, Function<String, ?>> fieldParsers = new HashMap<>();
    this.arrayGenerator = size -> (R[]) Array.newInstance(clazz, size);
    this.generator = generator;
    this.setters = new HashMap<>();
    for (final Field field : clazz.getFields()) {
      final Function<String, ?> parser = Modifier.isStatic(field.getModifiers()) ? null : fieldParsers.computeIfAbsent(field.getType(), CSV::getTypeParser);
      if (parser != null)
        this.setters.put(field.getName(), (final R obj, final String rawValue) -> {
          try {
            field.set(obj, rawValue.isEmpty() ? null : parser.apply(rawValue));
          } catch (final IllegalAccessException e) {
            throw new RuntimeException(e);
          }
        });
    }
  }

  /**
   * Reads and parses the contents of the given CSV file, and returns an array filled with populated
   * objects created with the previously given generator. Cells are parsed using their corresponding
   * field's {@code valueOf(String)} function.
   * @param path the path to a CSV file
   * @return the parsed data from the CSV file
   * @throws IOException if an I/O error occurs opening the file
   */
  @SuppressWarnings("unchecked")
  public R[] read(final Path path) throws IOException {
    try (final BufferedReader reader = Files.newBufferedReader(path)) {
      final BiConsumer<R, String>[] fieldSetters = Stream.of(headerSanitizer(reader.readLine()).split(",")).map(this::nameProcessor).map(setters::get).toArray(BiConsumer[]::new);
      final Stream<String> lines = reader.lines();
      return lines.filter(Predicate.not(String::isBlank)).map(line -> deserializeRecordString(line, fieldSetters, generator.get())).toArray(this.arrayGenerator);
    }
  }

  @SuppressWarnings("unchecked")
  private static Function<String, ?> getTypeParser(final Class<?> type) {
    try {
      return type.isAssignableFrom(String.class) ? Function.identity() : MethodHandleProxies.asInterfaceInstance(Function.class, MethodHandles.publicLookup().findStatic(type, "valueOf", MethodType.methodType(type, String.class)));
    } catch (final NoSuchMethodException | IllegalAccessException e) {
      return null;
    }
  }

  private static <R> R deserializeRecordString(final String recordString, final BiConsumer<R, String>[] fieldParseSetters, final R object) {
    final int recordStringLength = recordString.length();
    int fieldBeginIndex = 0, tryFieldEndFromIndex = 0, i = 0;
    while (tryFieldEndFromIndex < recordStringLength && i < fieldParseSetters.length) {
      final int tryFieldEndIndex = recordString.indexOf(',', tryFieldEndFromIndex);
      String field = recordString.substring(fieldBeginIndex, tryFieldEndIndex == -1 ? recordStringLength : tryFieldEndIndex).strip();
      if (!field.isEmpty() && (tryFieldEndFromIndex != fieldBeginIndex || field.charAt(0) == '"')) {
        final int fieldLength = field.length();
        if (countTrailing(field, '"') % 2 == 0) {
          tryFieldEndFromIndex = tryFieldEndIndex + 1;
          continue;
        } else
          field = field.substring(1, fieldLength - 1).replace("\"\"", "\"");
      }
      final BiConsumer<R, String> setter = fieldParseSetters[i];
      if (setter != null)
        setter.accept(object, field);
      tryFieldEndFromIndex = fieldBeginIndex = tryFieldEndIndex + 1;
      i++;
    }
    return object;
  }

  private static int countTrailing(final String str, final char c) {
    final int l = str.length();
    int count = 0;
    while (str.charAt(l - count - 1) == c && count < l)
      count++;
    return count;
  }

  public static final class ReflectionTable {
    public static <T> String create(final T[] objects, boolean colored) {
      final Field[] fields = Stream.of(objects).flatMap(object -> Stream.of(object.getClass().getFields())).distinct().toArray(Field[]::new);
      final List<List<ReflectionTable>> rows = new ArrayList<>();
      rows.add(Stream.of(fields).map(ReflectionTable::new).collect(Collectors.toList()));
      rows.addAll(Stream.of(objects).map(obj -> Stream.of(fields).map(field -> new ReflectionTable(obj, field)).collect(Collectors.toList())).collect(Collectors.toList()));
      final int[] columnWidths = rows.stream().map(row -> row.stream().map(cell -> cell.string).mapToInt(String::length).toArray()).reduce(new int[fields.length], (result, row) -> IntStream.range(0, row.length).map(i -> Math.max(result[i], row[i])).toArray());
      if (colored)
        IntStream.range(0, fields.length).forEach(i -> {
          final var columnSummaryStatistics = rows.stream().skip(1).mapToDouble(row -> row.get(i).getValue().doubleValue()).summaryStatistics();
          rows.stream().skip(1).forEach(row -> row.get(i).colorByValue(columnSummaryStatistics.getMin(), columnSummaryStatistics.getMax()));
        });
      MessageFormat formatFormat = new MessageFormat(colored ? "{2} %{0}{1}s {3}" : " %{0}{1}s ");
      return rows.stream().map(row -> IntStream.range(0, row.size()).mapToObj(i -> String.format(formatFormat.format(new Object[] { row.get(i).padRight ? "-" : "", columnWidths[i], row.get(i).escape, RESET_STYLE }), row.get(i).string)).collect(Collectors.joining("|"))).collect(Collectors.joining(LF));
    }

    private static final Color GRADIENT_MIN = new Color(0x00, 0x33, 0x00);
    private static final Color GRADIENT_MAX = new Color(0x00, 0xFF, 0x00);
    private static final String CONTROL = "\033";
    private static final String CSI = "[";
    private static final String LF = "\n";
    private static final String RESET = "0";
    private static final String BOLD = "1";
    private static final String ITALIC = "3";
    private static final String UNDERLINE = "4";
    private static final String BACKGROUND_RED = "41";
    private static final String FOREGROUND = "38";
    private static final String BACKGROUND = "48";
    private static final String TRUECOLOR = "2";
    private static final String SEPARATOR = ";";
    private static final String SGR = "m";
    private static final String HEADER_STYLE = CONTROL + CSI + BOLD + SEPARATOR + UNDERLINE + SGR;
    private static final String NULL_STYLE = CONTROL + CSI + ITALIC + SGR;
    private static final String ERROR_STYLE = CONTROL + CSI + ITALIC + SGR + CONTROL + CSI + BACKGROUND_RED + SGR;
    private static final String RESET_STYLE = CONTROL + CSI + RESET + SGR;
    private Object value;
    private String string;
    private boolean padRight;
    private String escape;

    private ReflectionTable(final Object obj, final Field field) {
      try {
        value = field.get(obj);
        string = Objects.toString(value);
        padRight = !Number.class.isAssignableFrom(field.getType());
        escape = Objects.isNull(value) ? NULL_STYLE : "";
      } catch (final IllegalAccessException | IllegalArgumentException e) {
        value = null;
        string = e.getClass().getSimpleName();
        padRight = false;
        escape = ERROR_STYLE;
      }
    }

    private ReflectionTable(final Field field) {
      value = null;
      string = field.getName();
      padRight = true;
      escape = HEADER_STYLE;
    }

    private Number getValue() {
      return padRight ? Objects.hashCode(string) : Objects.requireNonNullElse((Number) value, 0);
    }

    private void colorByValue(final Number min, final Number max) {
      if (Objects.nonNull(value)) {
        final double range = max.doubleValue() - min.doubleValue();
        final double normal = range == 0 ? 0 : (getValue().doubleValue() - min.doubleValue()) / range;
        final Color color = new Color(range(normal, GRADIENT_MIN.getRed(), GRADIENT_MAX.getRed()), range(normal, GRADIENT_MIN.getGreen(), GRADIENT_MAX.getGreen()), range(normal, GRADIENT_MIN.getBlue(), GRADIENT_MAX.getBlue()));
        escape += (contrastRatio(color, Color.BLACK) > contrastRatio(Color.WHITE, color) ? colorTo24BitSGR(Color.BLACK, false) : colorTo24BitSGR(Color.WHITE, false)) + colorTo24BitSGR(color, true);
      }
    }

    private static String colorTo24BitSGR(final Color color, final boolean background) {
      return CONTROL + CSI + (background ? BACKGROUND : FOREGROUND) + SEPARATOR + TRUECOLOR + SEPARATOR + color.getRed() + SEPARATOR + color.getGreen() + SEPARATOR + color.getBlue() + SGR;
    }

    private static int range(final double normal, final int min, final int max) {
      return (int) (normal * (max - min) + min);
    }

    /* https://www.w3.org/TR/WCAG20/#contrast-ratiodef */
    private static float contrastRatio(final Color lighter, final Color darker) {
      return (relativeLuminance(lighter) + 0.05f) / (relativeLuminance(darker) + 0.05f);
    }

    /* https://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef */
    private static float relativeLuminance(final Color color) {
      final float[] components = color.getRGBComponents(null);
      final float r = components[0] <= 0.03928f ? components[0] / 12.92f : (float) Math.pow((components[0] + 0.055f) / 1.055f, 2.4f);
      final float g = components[1] <= 0.03928f ? components[1] / 12.92f : (float) Math.pow((components[1] + 0.055f) / 1.055f, 2.4f);
      final float b = components[2] <= 0.03928f ? components[2] / 12.92f : (float) Math.pow((components[2] + 0.055f) / 1.055f, 2.4f);
      return 0.2126f * r + 0.7152f * g + 0.0722f * b;
    }
  }
}