// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Globalization;
using System.Diagnostics;
using System.Diagnostics.Contracts;
using System.Text;

namespace System
{
    // A Version object contains four hierarchical numeric components: major, minor,
    // build and revision.  Build and revision may be unspecified, which is represented 
    // internally as a -1.  By definition, an unspecified component matches anything 
    // (both unspecified and specified), and an unspecified component is "less than" any
    // specified component.

    [Serializable]
    public sealed class Version : ICloneable, IComparable
        , IComparable<Version>, IEquatable<Version>
    {
        // AssemblyName depends on the order staying the same
        private readonly int _Major;
        private readonly int _Minor;
        private readonly int _Build = -1;
        private readonly int _Revision = -1;

        public Version(int major, int minor, int build, int revision)
        {
            if (major < 0)
                throw new ArgumentOutOfRangeException(nameof(major), SR.ArgumentOutOfRange_Version);

            if (minor < 0)
                throw new ArgumentOutOfRangeException(nameof(minor), SR.ArgumentOutOfRange_Version);

            if (build < 0)
                throw new ArgumentOutOfRangeException(nameof(build), SR.ArgumentOutOfRange_Version);

            if (revision < 0)
                throw new ArgumentOutOfRangeException(nameof(revision), SR.ArgumentOutOfRange_Version);
            Contract.EndContractBlock();

            _Major = major;
            _Minor = minor;
            _Build = build;
            _Revision = revision;
        }

        public Version(int major, int minor, int build)
        {
            if (major < 0)
                throw new ArgumentOutOfRangeException(nameof(major), SR.ArgumentOutOfRange_Version);

            if (minor < 0)
                throw new ArgumentOutOfRangeException(nameof(minor), SR.ArgumentOutOfRange_Version);

            if (build < 0)
                throw new ArgumentOutOfRangeException(nameof(build), SR.ArgumentOutOfRange_Version);

            Contract.EndContractBlock();

            _Major = major;
            _Minor = minor;
            _Build = build;
        }

        public Version(int major, int minor)
        {
            if (major < 0)
                throw new ArgumentOutOfRangeException(nameof(major), SR.ArgumentOutOfRange_Version);

            if (minor < 0)
                throw new ArgumentOutOfRangeException(nameof(minor), SR.ArgumentOutOfRange_Version);
            Contract.EndContractBlock();

            _Major = major;
            _Minor = minor;
        }

        public Version(String version)
        {
            Version v = Version.Parse(version);
            _Major = v.Major;
            _Minor = v.Minor;
            _Build = v.Build;
            _Revision = v.Revision;
        }

        public Version()
        {
            _Major = 0;
            _Minor = 0;
        }

        private Version(Version version)
        {
            Debug.Assert(version != null);

            _Major = version._Major;
            _Minor = version._Minor;
            _Build = version._Build;
            _Revision = version._Revision;
        }

        public object Clone()
        {
            return new Version(this);
        }

        // Properties for setting and getting version numbers
        public int Major
        {
            get { return _Major; }
        }

        public int Minor
        {
            get { return _Minor; }
        }

        public int Build
        {
            get { return _Build; }
        }

        public int Revision
        {
            get { return _Revision; }
        }

        public short MajorRevision
        {
            get { return (short)(_Revision >> 16); }
        }

        public short MinorRevision
        {
            get { return (short)(_Revision & 0xFFFF); }
        }

        public int CompareTo(Object version)
        {
            if (version == null)
            {
                return 1;
            }

            Version v = version as Version;
            if (v == null)
            {
                throw new ArgumentException(SR.Arg_MustBeVersion);
            }

            return CompareTo(v);
        }

        public int CompareTo(Version value)
        {
            return
                object.ReferenceEquals(value, this) ? 0 :
                object.ReferenceEquals(value, null) ? 1 :
                _Major != value._Major ? (_Major > value._Major ? 1 : -1) :
                _Minor != value._Minor ? (_Minor > value._Minor ? 1 : -1) :
                _Build != value._Build ? (_Build > value._Build ? 1 : -1) :
                _Revision != value._Revision ? (_Revision > value._Revision ? 1 : -1) :
                0;
        }

        public override bool Equals(Object obj)
        {
            return Equals(obj as Version);
        }

        public bool Equals(Version obj)
        {
            return object.ReferenceEquals(obj, this) ||
                (!object.ReferenceEquals(obj, null) &&
                _Major == obj._Major &&
                _Minor == obj._Minor &&
                _Build == obj._Build &&
                _Revision == obj._Revision);
        }

        public override int GetHashCode()
        {
            // Let's assume that most version numbers will be pretty small and just
            // OR some lower order bits together.

            int accumulator = 0;

            accumulator |= (_Major & 0x0000000F) << 28;
            accumulator |= (_Minor & 0x000000FF) << 20;
            accumulator |= (_Build & 0x000000FF) << 12;
            accumulator |= (_Revision & 0x00000FFF);

            return accumulator;
        }

        public override String ToString()
        {
            if (_Build == -1) return (ToString(2));
            if (_Revision == -1) return (ToString(3));
            return (ToString(4));
        }

        public String ToString(int fieldCount)
        {
            StringBuilder sb;
            switch (fieldCount)
            {
                case 0:
                    return (String.Empty);
                case 1:
                    return (_Major.ToString());
                case 2:
                    sb = StringBuilderCache.Acquire();
                    AppendPositiveNumber(_Major, sb);
                    sb.Append('.');
                    AppendPositiveNumber(_Minor, sb);
                    return StringBuilderCache.GetStringAndRelease(sb);
                default:
                    if (_Build == -1)
                        throw new ArgumentException(SR.Format(SR.ArgumentOutOfRange_Bounds_Lower_Upper, "0", "2"), nameof(fieldCount));

                    if (fieldCount == 3)
                    {
                        sb = StringBuilderCache.Acquire();
                        AppendPositiveNumber(_Major, sb);
                        sb.Append('.');
                        AppendPositiveNumber(_Minor, sb);
                        sb.Append('.');
                        AppendPositiveNumber(_Build, sb);
                        return StringBuilderCache.GetStringAndRelease(sb);
                    }

                    if (_Revision == -1)
                        throw new ArgumentException(SR.Format(SR.ArgumentOutOfRange_Bounds_Lower_Upper, "0", "3"), nameof(fieldCount));

                    if (fieldCount == 4)
                    {
                        sb = StringBuilderCache.Acquire();
                        AppendPositiveNumber(_Major, sb);
                        sb.Append('.');
                        AppendPositiveNumber(_Minor, sb);
                        sb.Append('.');
                        AppendPositiveNumber(_Build, sb);
                        sb.Append('.');
                        AppendPositiveNumber(_Revision, sb);
                        return StringBuilderCache.GetStringAndRelease(sb);
                    }

                    throw new ArgumentException(SR.Format(SR.ArgumentOutOfRange_Bounds_Lower_Upper, "0", "4"), nameof(fieldCount));
            }
        }

        //
        // AppendPositiveNumber is an optimization to append a number to a StringBuilder object without
        // doing any boxing and not even creating intermediate string.
        // Note: as we always have positive numbers then it is safe to convert the number to string 
        // regardless of the current culture as we'll not have any punctuation marks in the number
        //
        private const int ZERO_CHAR_VALUE = (int)'0';
        private static void AppendPositiveNumber(int num, StringBuilder sb)
        {
            Debug.Assert(num >= 0, "AppendPositiveNumber expect positive numbers");

            int index = sb.Length;
            int reminder;

            do
            {
                reminder = num % 10;
                num = num / 10;
                sb.Insert(index, (char)(ZERO_CHAR_VALUE + reminder));
            } while (num > 0);
        }

        public static Version Parse(string input)
        {
            if (input == null)
            {
                throw new ArgumentNullException(nameof(input));
            }
            Contract.EndContractBlock();

            VersionResult r = new VersionResult();
            r.Init(nameof(input), true);
            if (!TryParseVersion(input, ref r))
            {
                throw r.GetVersionParseException();
            }
            return r.m_parsedVersion;
        }

        public static bool TryParse(string input, out Version result)
        {
            VersionResult r = new VersionResult();
            r.Init(nameof(input), false);
            bool b = TryParseVersion(input, ref r);
            result = r.m_parsedVersion;
            return b;
        }

        private static bool TryParseVersion(string version, ref VersionResult result)
        {
            int major, minor, build, revision;

            if ((Object)version == null)
            {
                result.SetFailure(ParseFailureKind.ArgumentNullException);
                return false;
            }

            String[] parsedComponents = version.Split('.');
            int parsedComponentsLength = parsedComponents.Length;
            if ((parsedComponentsLength < 2) || (parsedComponentsLength > 4))
            {
                result.SetFailure(ParseFailureKind.ArgumentException);
                return false;
            }

            if (!TryParseComponent(parsedComponents[0], nameof(version), ref result, out major))
            {
                return false;
            }

            if (!TryParseComponent(parsedComponents[1], nameof(version), ref result, out minor))
            {
                return false;
            }

            parsedComponentsLength -= 2;

            if (parsedComponentsLength > 0)
            {
                if (!TryParseComponent(parsedComponents[2], "build", ref result, out build))
                {
                    return false;
                }

                parsedComponentsLength--;

                if (parsedComponentsLength > 0)
                {
                    if (!TryParseComponent(parsedComponents[3], "revision", ref result, out revision))
                    {
                        return false;
                    }
                    else
                    {
                        result.m_parsedVersion = new Version(major, minor, build, revision);
                    }
                }
                else
                {
                    result.m_parsedVersion = new Version(major, minor, build);
                }
            }
            else
            {
                result.m_parsedVersion = new Version(major, minor);
            }

            return true;
        }

        private static bool TryParseComponent(string component, string componentName, ref VersionResult result, out int parsedComponent)
        {
            if (!Int32.TryParse(component, NumberStyles.Integer, CultureInfo.InvariantCulture, out parsedComponent))
            {
                result.SetFailure(ParseFailureKind.FormatException, component);
                return false;
            }

            if (parsedComponent < 0)
            {
                result.SetFailure(ParseFailureKind.ArgumentOutOfRangeException, componentName);
                return false;
            }

            return true;
        }

        public static bool operator ==(Version v1, Version v2)
        {
            if (Object.ReferenceEquals(v1, null))
            {
                return Object.ReferenceEquals(v2, null);
            }

            return v1.Equals(v2);
        }

        public static bool operator !=(Version v1, Version v2)
        {
            return !(v1 == v2);
        }

        public static bool operator <(Version v1, Version v2)
        {
            if ((Object)v1 == null)
                throw new ArgumentNullException(nameof(v1));
            Contract.EndContractBlock();
            return (v1.CompareTo(v2) < 0);
        }

        public static bool operator <=(Version v1, Version v2)
        {
            if ((Object)v1 == null)
                throw new ArgumentNullException(nameof(v1));
            Contract.EndContractBlock();
            return (v1.CompareTo(v2) <= 0);
        }

        public static bool operator >(Version v1, Version v2)
        {
            return (v2 < v1);
        }

        public static bool operator >=(Version v1, Version v2)
        {
            return (v2 <= v1);
        }

        internal enum ParseFailureKind
        {
            ArgumentNullException,
            ArgumentException,
            ArgumentOutOfRangeException,
            FormatException
        }

        internal struct VersionResult
        {
            internal Version m_parsedVersion;
            internal ParseFailureKind m_failure;
            internal string m_exceptionArgument;
            internal string m_argumentName;
            internal bool m_canThrow;

            internal void Init(string argumentName, bool canThrow)
            {
                m_canThrow = canThrow;
                m_argumentName = argumentName;
            }

            internal void SetFailure(ParseFailureKind failure)
            {
                SetFailure(failure, String.Empty);
            }

            internal void SetFailure(ParseFailureKind failure, string argument)
            {
                m_failure = failure;
                m_exceptionArgument = argument;
                if (m_canThrow)
                {
                    throw GetVersionParseException();
                }
            }

            internal Exception GetVersionParseException()
            {
                switch (m_failure)
                {
                    case ParseFailureKind.ArgumentNullException:
                        return new ArgumentNullException(m_argumentName);
                    case ParseFailureKind.ArgumentException:
                        return new ArgumentException(SR.Arg_VersionString);
                    case ParseFailureKind.ArgumentOutOfRangeException:
                        return new ArgumentOutOfRangeException(m_exceptionArgument, SR.ArgumentOutOfRange_Version);
                    case ParseFailureKind.FormatException:
                        // Regenerate the FormatException as would be thrown by Int32.Parse()
                        try
                        {
                            Int32.Parse(m_exceptionArgument, CultureInfo.InvariantCulture);
                        }
                        catch (FormatException e)
                        {
                            return e;
                        }
                        catch (OverflowException e)
                        {
                            return e;
                        }
                        Debug.Assert(false, "Int32.Parse() did not throw exception but TryParse failed: " + m_exceptionArgument);
                        return new FormatException(SR.Format_InvalidString);
                    default:
                        Debug.Assert(false, "Unmatched case in Version.GetVersionParseException() for value: " + m_failure);
                        return new ArgumentException(SR.Arg_VersionString);
                }
            }
        }
    }
}