/* Copyright (C) 2011  Jan Källman
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.

 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * The GNU Lesser General Public License can be viewed at http://www.opensource.org/licenses/lgpl-license.php
 * If you unfamiliar with this license or have questions about it, here is an http://www.gnu.org/licenses/gpl-faq.html
 *
 * All code and executables are provided "as is" with no warranty either express or implied.
 * The author accepts no liability for any damage or loss of business that this product may cause.
 *
 * Code change notes:
 *
 * Author							Change						Date
 *******************************************************************************
 * Mats Alm   		                Added		                2013-12-03
 *******************************************************************************/

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace AppsheetEpplus;

/// <summary>
/// Base class for Excel function implementations.
/// </summary>
public abstract class ExcelFunction {
  public ExcelFunction()
      : this(new(), new(), new()) {}

  public ExcelFunction(
      ArgumentCollectionUtil argumentCollectionUtil,
      ArgumentParsers argumentParsers,
      CompileResultValidators compileResultValidators) {
    _argumentCollectionUtil = argumentCollectionUtil;
    _argumentParsers = argumentParsers;
    _compileResultValidators = compileResultValidators;
  }

  private readonly ArgumentCollectionUtil _argumentCollectionUtil;
  private readonly ArgumentParsers _argumentParsers;
  private readonly CompileResultValidators _compileResultValidators;

  /// <summary>
  ///
  /// </summary>
  /// <param name="arguments">Arguments to the function, each argument can contain primitive types, lists or <see cref="ExcelDataProvider.IRangeInfo">Excel ranges</see></param>
  /// <param name="context">The <see cref="ParsingContext"/> contains various data that can be useful in functions.</param>
  /// <returns>A <see cref="CompileResult"/> containing the calculated value</returns>
  public abstract CompileResult Execute(
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context);

  /// <summary>
  /// If overridden, this method is called before Execute is called.
  /// </summary>
  /// <param name="context"></param>
  public virtual void BeforeInvoke(ParsingContext context) {}

  public virtual bool IsLookupFuction => false;

  public virtual bool IsErrorHandlingFunction => false;

  /// <summary>
  /// Used for some Lookupfunctions to indicate that function arguments should
  /// not be compiled before the function is called.
  /// </summary>
  public bool SkipArgumentEvaluation { get; set; }

  protected object GetFirstValue(IEnumerable<FunctionArgument> val) {
    var arg = val.FirstOrDefault();
    if (arg.Value is ExcelDataProvider.IRangeInfo) {
      //var r=((ExcelDataProvider.IRangeInfo)arg);
      var r = arg.ValueAsRangeInfo;
      return r.GetValue(r.Address._fromRow, r.Address._fromCol);
    }
    return arg?.Value;
  }

  /// <summary>
  /// This functions validates that the supplied <paramref name="arguments"/> contains at least
  /// (the value of) <paramref name="minLength"/> elements. If one of the arguments is an
  /// <see cref="ExcelDataProvider.IRangeInfo">Excel range</see> the number of cells in
  /// that range will be counted as well.
  /// </summary>
  /// <param name="arguments"></param>
  /// <param name="minLength"></param>
  /// <param name="errorTypeToThrow">The <see cref="eErrorType"/> of the <see cref="ExcelErrorValueException"/> that will be thrown if <paramref name="minLength"/> is not met.</param>
  protected void ValidateArguments(
      IEnumerable<FunctionArgument> arguments,
      int minLength,
      eErrorType errorTypeToThrow) {
    Require.That(arguments).Named("arguments").IsNotNull();
    ThrowExcelErrorValueExceptionIf(
        () => {
          var nArgs = 0;
          if (arguments.Any()) {
            foreach (var arg in arguments) {
              nArgs++;
              if (nArgs >= minLength) {
                return false;
              }
              if (arg.IsExcelRange) {
                nArgs += arg.ValueAsRangeInfo.GetNCells();
                if (nArgs >= minLength) {
                  return false;
                }
              }
            }
          }
          return true;
        },
        errorTypeToThrow);
  }

  /// <summary>
  /// This functions validates that the supplied <paramref name="arguments"/> contains at least
  /// (the value of) <paramref name="minLength"/> elements. If one of the arguments is an
  /// <see cref="ExcelDataProvider.IRangeInfo">Excel range</see> the number of cells in
  /// that range will be counted as well.
  /// </summary>
  /// <param name="arguments"></param>
  /// <param name="minLength"></param>
  /// <exception cref="ArgumentException"></exception>
  protected void ValidateArguments(IEnumerable<FunctionArgument> arguments, int minLength) {
    Require.That(arguments).Named("arguments").IsNotNull();
    ThrowArgumentExceptionIf(
        () => {
          var nArgs = 0;
          if (arguments.Any()) {
            foreach (var arg in arguments) {
              nArgs++;
              if (nArgs >= minLength) {
                return false;
              }
              if (arg.IsExcelRange) {
                nArgs += arg.ValueAsRangeInfo.GetNCells();
                if (nArgs >= minLength) {
                  return false;
                }
              }
            }
          }
          return true;
        },
        "Expecting at least {0} arguments",
        minLength.ToString());
  }

  /// <summary>
  /// Returns the value of the argument att the position of the 0-based
  /// <paramref name="index"/> as an integer.
  /// </summary>
  /// <param name="arguments"></param>
  /// <param name="index"></param>
  /// <returns>Value of the argument as an integer.</returns>
  /// <exception cref="ExcelErrorValueException"></exception>
  protected int ArgToInt(IEnumerable<FunctionArgument> arguments, int index) {
    var val = arguments.ElementAt(index).ValueFirst;
    return (int)_argumentParsers.GetParser(DataType.Integer).Parse(val);
  }

  /// <summary>
  /// Returns the value of the argument att the position of the 0-based
  /// <paramref name="index"/> as a string.
  /// </summary>
  /// <param name="arguments"></param>
  /// <param name="index"></param>
  /// <returns>Value of the argument as a string.</returns>
  protected string ArgToString(IEnumerable<FunctionArgument> arguments, int index) {
    var obj = arguments.ElementAt(index).ValueFirst;
    return obj != null ? obj.ToString() : string.Empty;
  }

  /// <summary>
  /// Returns the value of the argument att the position of the 0-based
  /// </summary>
  /// <param name="obj"></param>
  /// <returns>Value of the argument as a double.</returns>
  /// <exception cref="ExcelErrorValueException"></exception>
  protected double ArgToDecimal(object obj) {
    return (double)_argumentParsers.GetParser(DataType.Decimal).Parse(obj);
  }

  /// <summary>
  /// Returns the value of the argument att the position of the 0-based
  /// <paramref name="index"/> as a <see cref="System.Double"/>.
  /// </summary>
  /// <param name="arguments"></param>
  /// <param name="index"></param>
  /// <returns>Value of the argument as an integer.</returns>
  /// <exception cref="ExcelErrorValueException"></exception>
  protected double ArgToDecimal(IEnumerable<FunctionArgument> arguments, int index) {
    return ArgToDecimal(arguments.ElementAt(index).Value);
  }

  protected double Divide(double left, double right) {
    if (System.Math.Abs(right - 0d) < double.Epsilon) {
      throw new ExcelErrorValueException(eErrorType.Div0);
    }
    return left / right;
  }

  protected bool IsNumericString(object value) {
    if (value == null || string.IsNullOrEmpty(value.ToString())) {
      return false;
    }
    return Regex.IsMatch(value.ToString(), @"^[\d]+(\,[\d])?");
  }

  /// <summary>
  /// If the argument is a boolean value its value will be returned.
  /// If the argument is an integer value, true will be returned if its
  /// value is not 0, otherwise false.
  /// </summary>
  /// <param name="arguments"></param>
  /// <param name="index"></param>
  /// <returns></returns>
  protected bool ArgToBool(IEnumerable<FunctionArgument> arguments, int index) {
    var obj = arguments.ElementAt(index).Value ?? string.Empty;
    return (bool)_argumentParsers.GetParser(DataType.Boolean).Parse(obj);
  }

  /// <summary>
  /// Throws an <see cref="ArgumentException"/> if <paramref name="condition"/> evaluates to true.
  /// </summary>
  /// <param name="condition"></param>
  /// <param name="message"></param>
  /// <exception cref="ArgumentException"></exception>
  protected void ThrowArgumentExceptionIf(Func<bool> condition, string message) {
    if (condition()) {
      throw new ArgumentException(message);
    }
  }

  /// <summary>
  /// Throws an <see cref="ArgumentException"/> if <paramref name="condition"/> evaluates to true.
  /// </summary>
  /// <param name="condition"></param>
  /// <param name="message"></param>
  /// <param name="formats">Formats to the message string.</param>
  protected void ThrowArgumentExceptionIf(
      Func<bool> condition,
      string message,
      params object[] formats) {
    message = string.Format(message, formats);
    ThrowArgumentExceptionIf(condition, message);
  }

  /// <summary>
  /// Throws an <see cref="ExcelErrorValueException"/> with the given <paramref name="errorType"/> set.
  /// </summary>
  /// <param name="errorType"></param>
  protected void ThrowExcelErrorValueException(eErrorType errorType) {
    throw new ExcelErrorValueException(
        "An excel function error occurred",
        ExcelErrorValue.Create(errorType));
  }

  /// <summary>
  /// Throws an <see cref="ArgumentException"/> if <paramref name="condition"/> evaluates to true.
  /// </summary>
  /// <param name="condition"></param>
  /// <param name="errorType"></param>
  /// <exception cref="ExcelErrorValueException"></exception>
  protected void ThrowExcelErrorValueExceptionIf(Func<bool> condition, eErrorType errorType) {
    if (condition()) {
      throw new ExcelErrorValueException(
          "An excel function error occurred",
          ExcelErrorValue.Create(errorType));
    }
  }

  protected bool IsNumeric(object val) {
    if (val == null) {
      return false;
    }
    return (val.GetType().IsPrimitive
            || val is double
            || val is decimal
            || val is System.DateTime
            || val is TimeSpan);
  }

  //protected virtual bool IsNumber(object obj)
  //{
  //    if (obj == null) return false;
  //    return (obj is int || obj is double || obj is short || obj is decimal || obj is long);
  //}

  /// <summary>
  /// Helper method for comparison of two doubles.
  /// </summary>
  /// <param name="d1"></param>
  /// <param name="d2"></param>
  /// <returns></returns>
  protected bool AreEqual(double d1, double d2) {
    return System.Math.Abs(d1 - d2) < double.Epsilon;
  }

  /// <summary>
  /// Will return the arguments as an enumerable of doubles.
  /// </summary>
  /// <param name="arguments"></param>
  /// <param name="context"></param>
  /// <returns></returns>
  protected virtual IEnumerable<double> ArgsToDoubleEnumerable(
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context) {
    return ArgsToDoubleEnumerable(false, arguments, context);
  }

  /// <summary>
  /// Will return the arguments as an enumerable of doubles.
  /// </summary>
  /// <param name="ignoreHiddenCells">If a cell is hidden and this value is true the value of that cell will be ignored</param>
  /// <param name="ignoreErrors">If a cell contains an error, that error will be ignored if this method is set to true</param>
  /// <param name="arguments"></param>
  /// <param name="context"></param>
  /// <returns></returns>
  protected virtual IEnumerable<double> ArgsToDoubleEnumerable(
      bool ignoreHiddenCells,
      bool ignoreErrors,
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context) {
    return _argumentCollectionUtil.ArgsToDoubleEnumerable(
        ignoreHiddenCells,
        ignoreErrors,
        arguments,
        context);
  }

  /// <summary>
  /// Will return the arguments as an enumerable of doubles.
  /// </summary>
  /// <param name="ignoreHiddenCells">If a cell is hidden and this value is true the value of that cell will be ignored</param>
  /// <param name="arguments"></param>
  /// <param name="context"></param>
  /// <returns></returns>
  protected virtual IEnumerable<double> ArgsToDoubleEnumerable(
      bool ignoreHiddenCells,
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context) {
    return ArgsToDoubleEnumerable(ignoreHiddenCells, true, arguments, context);
  }

  /// <summary>
  /// Will return the arguments as an enumerable of objects.
  /// </summary>
  /// <param name="ignoreHiddenCells">If a cell is hidden and this value is true the value of that cell will be ignored</param>
  /// <param name="arguments"></param>
  /// <param name="context"></param>
  /// <returns></returns>
  protected virtual IEnumerable<object> ArgsToObjectEnumerable(
      bool ignoreHiddenCells,
      IEnumerable<FunctionArgument> arguments,
      ParsingContext context) {
    return _argumentCollectionUtil.ArgsToObjectEnumerable(ignoreHiddenCells, arguments, context);
  }

  /// <summary>
  /// Use this method to create a result to return from Excel functions.
  /// </summary>
  /// <param name="result"></param>
  /// <param name="dataType"></param>
  /// <returns></returns>
  protected CompileResult CreateResult(object result, DataType dataType) {
    var validator = _compileResultValidators.GetValidator(dataType);
    validator.Validate(result);
    return new(result, dataType);
  }

  /// <summary>
  /// Use this method to apply a function on a collection of arguments. The <paramref name="result"/>
  /// should be modifyed in the supplied <paramref name="action"/> and will contain the result
  /// after this operation has been performed.
  /// </summary>
  /// <param name="collection"></param>
  /// <param name="result"></param>
  /// <param name="action"></param>
  /// <returns></returns>
  protected virtual double CalculateCollection(
      IEnumerable<FunctionArgument> collection,
      double result,
      Func<FunctionArgument, double, double> action) {
    return _argumentCollectionUtil.CalculateCollection(collection, result, action);
  }

  /// <summary>
  /// if the supplied <paramref name="arg">argument</paramref> contains an Excel error
  /// an <see cref="ExcelErrorValueException"/> with that errorcode will be thrown
  /// </summary>
  /// <param name="arg"></param>
  /// <exception cref="ExcelErrorValueException"></exception>
  protected void CheckForAndHandleExcelError(FunctionArgument arg) {
    if (arg.ValueIsExcelError) {
      throw (new ExcelErrorValueException(arg.ValueAsExcelErrorValue));
    }
  }

  /// <summary>
  /// If the supplied <paramref name="cell"/> contains an Excel error
  /// an <see cref="ExcelErrorValueException"/> with that errorcode will be thrown
  /// </summary>
  /// <param name="cell"></param>
  protected void CheckForAndHandleExcelError(ExcelDataProvider.ICellInfo cell) {
    if (cell.IsExcelError) {
      throw (new ExcelErrorValueException(ExcelErrorValue.Parse(cell.Value.ToString())));
    }
  }

  protected CompileResult GetResultByObject(object result) {
    if (IsNumeric(result)) {
      return CreateResult(result, DataType.Decimal);
    }
    if (result is string) {
      return CreateResult(result, DataType.String);
    }
    if (ExcelErrorValue.Values.IsErrorValue(result)) {
      return CreateResult(result, DataType.ExcelAddress);
    }
    if (result == null) {
      return CompileResult.Empty;
    }
    return CreateResult(result, DataType.Enumerable);
  }
}