using Microsoft.Build.Construction;
using Microsoft.Build.Exceptions;
using System;
using System.Collections.Generic;
using System.Linq;
using Semmle.Util;
using System.IO;
using Semmle.Util.Logging;

namespace Semmle.Autobuild
{
    /// <summary>
    /// A solution file, extension .sln.
    /// </summary>
    public interface ISolution : IProjectOrSolution
    {
        /// <summary>
        /// Solution configurations.
        /// </summary>
        IEnumerable<SolutionConfigurationInSolution> Configurations { get; }

        /// <summary>
        /// The default configuration name, e.g. "Release"
        /// </summary>
        string DefaultConfigurationName { get; }

        /// <summary>
        /// The default platform name, e.g. "x86"
        /// </summary>
        string DefaultPlatformName { get; }

        /// <summary>
        /// Gets the "best" tools version for this solution.
        /// If there are several versions, because the project files
        /// are inconsistent, then pick the highest/latest version.
        /// If no tools versions are present, return 0.0.0.0.
        /// </summary>
        Version ToolsVersion { get; }
    }

    /// <summary>
    /// A solution file on the filesystem, read using Microsoft.Build.
    /// </summary>
    class Solution : ProjectOrSolution, ISolution
    {
        readonly SolutionFile solution;

        readonly IEnumerable<Project> includedProjects;
        public override IEnumerable<IProjectOrSolution> IncludedProjects => includedProjects;

        public IEnumerable<SolutionConfigurationInSolution> Configurations =>
            solution == null ? Enumerable.Empty<SolutionConfigurationInSolution>() : solution.SolutionConfigurations;

        public string DefaultConfigurationName =>
            solution == null ? "" : solution.GetDefaultConfigurationName();

        public string DefaultPlatformName =>
            solution == null ? "" : solution.GetDefaultPlatformName();

        public Solution(Autobuilder builder, string path, bool allowProject) : base(builder, path)
        {
            try
            {
                solution = SolutionFile.Parse(FullPath);
            }
            catch (Exception e) when (e is InvalidProjectFileException || e is FileNotFoundException)
            {
                // We allow specifying projects as solutions in lgtm.yml, so model
                // that scenario as a solution with just that one project
                if (allowProject)
                {
                    includedProjects = new[] { new Project(builder, path) };
                    return;
                }

                builder.Log(Severity.Info, $"Unable to read solution file {path}.");
                includedProjects = new Project[0];
                return;
            }

            includedProjects =
                solution.ProjectsInOrder.
                Where(p => p.ProjectType == SolutionProjectType.KnownToBeMSBuildFormat).
                Select(p => builder.Actions.PathCombine(Path.GetDirectoryName(path), builder.Actions.PathCombine(p.RelativePath.Split('\\', StringSplitOptions.RemoveEmptyEntries)))).
                Select(p => new Project(builder, p)).
                ToArray();
        }

        IEnumerable<Version> ToolsVersions => includedProjects.Where(p => p.ValidToolsVersion).Select(p => p.ToolsVersion);

        public Version ToolsVersion => ToolsVersions.Any() ? ToolsVersions.Max() : new Version();
    }
}