using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text.RegularExpressions;
using Microsoft.Build.Construction;
using Microsoft.Xna.Framework.Content.Pipeline;
using Newtonsoft.Json;

namespace Contentless;

public static class Program {
    public static void Main(string[] args) {
        if (args.Length < 1) {
            Console.WriteLine("Please specify the location of the content file you want to use");
            return;
        }

        var contentFile = new FileInfo(Path.GetFullPath(Path.Combine(Environment.CurrentDirectory, args[0])));
        if (!contentFile.Exists) {
            Console.WriteLine($"Unable to find content file {contentFile}");
            return;
        }

        Console.WriteLine($"Using content file {contentFile}");
        var content = Program.ReadContent(contentFile);

        // load config
        var config = new Config();
        var configFile = new FileInfo(Path.Combine(contentFile.DirectoryName!, "Contentless.json"));
        if (configFile.Exists) {
            using var stream = configFile.OpenText();
            try {
                config = JsonConvert.DeserializeObject<Config>(stream.ReadToEnd());
                Console.WriteLine($"Using config from {configFile}");
            } catch (Exception e) {
                Console.WriteLine($"Error loading config from {configFile}: {e}");
            }
        } else {
            Console.WriteLine("Using default config");
        }
        var excluded = config.ExcludedFiles.Select(Program.MakeFileRegex).ToArray();
        var overrides = Program.GetOverrides(config.Overrides).ToArray();

        var referencesVersions = config.References.ToDictionary(x => x, x => (string)null, StringComparer.OrdinalIgnoreCase);
        if (config.References.Length > 0) {
            if (args.Length > 1) {
                ExtractVersions(args[1], referencesVersions);
                _nuGetHelper = new NuGetHelper(Path.GetDirectoryName(args[1]));
            }
            else
                Console.Error.WriteLine("You supplied references but there is no project file, this isn't compatible. Please specify the full path of project file, if you want to sync references");
        }
        
        const string ReferenceHeader = "/reference:";
        var changed = false;
        var referencesSyncs = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
        // load any references to be able to include custom content types as well
        for (int i = 0; i < content.Count; i++) {
            var line = content[i];
            if (!line.StartsWith(ReferenceHeader))
                continue;
            var reference = line.Substring(ReferenceHeader.Length);
            var libraryName = Path.GetFileName(reference)[..^4];

            if (referencesVersions.TryGetValue(libraryName, out var version) && version is not null) {
                var fullLibraryPath = CalculateFullPathToLibrary(libraryName, version);
                if (reference != fullLibraryPath) {
                    Console.WriteLine($"Changing library reference from {reference} to {fullLibraryPath}");
                    reference = fullLibraryPath;
                    content[i] = ReferenceHeader + fullLibraryPath;
                    changed = true;
                }
                else
                    Console.WriteLine($"Skipping library reference {fullLibraryPath} (success sync)");

                referencesSyncs.Add(libraryName);
            }
            
            var refPath = Path.GetFullPath(Path.Combine(contentFile.DirectoryName, reference));
            SafeAssemblyLoad(refPath);
        }

        // check references not in .mgcb now
        var referencesLastIndex = 0;
        // find place where I can add new reference
        for (int i = 0; i < content.Count; i++)
        {
            var line = content[i];
            if (line.StartsWith(ReferenceHeader))
                referencesLastIndex = i + 1;
            else if (line.StartsWith("/importer:") || line.StartsWith("/processor:") || line.StartsWith("/build:") ||
                     line.Contains("-- Content --")) {
                if (referencesLastIndex == 0)
                    referencesLastIndex = i;
                break;
            }
        }
        foreach (var reference in referencesVersions)
            if (!referencesSyncs.Contains(reference.Key) && reference.Value is not null) {
                try {
                    var path = CalculateFullPathToLibrary(reference.Key, reference.Value);
                    content.Insert(referencesLastIndex++, ReferenceHeader + path);
                    changed = true;
                    SafeAssemblyLoad(path);
                    Console.WriteLine($"Adding reference for {path} in .mgcb");
                }
                catch (Exception e)
                {
                    Console.Error.WriteLine($"Error adding library {reference.Key} in .mgcb: {e}");
                }
            }
        

        // load content importers
        var (importers, processors) = Program.GetContentData();
        Console.WriteLine($"Found possible importer types {string.Join(", ", importers)}");
        Console.WriteLine($"Found possible processor types {string.Join(", ", processors)}");

        foreach (var file in contentFile.Directory.EnumerateFiles("*", SearchOption.AllDirectories)) {
            // is the file the content or config file?
            if (file.Name == contentFile.Name || file.Name == configFile.Name)
                continue;
            var relative = Program.GetRelativePath(contentFile.DirectoryName, file.FullName).Replace("\\", "/");

            // is the file in an excluded directory?
            if (excluded.Any(e => e.IsMatch(relative))) {
                if (config.LogSkipped)
                    Console.WriteLine($"Skipping excluded file {relative}");
                continue;
            }

            // is the file already in the content file?
            if (Program.HasEntry(content, relative)) {
                if (config.LogSkipped)
                    Console.WriteLine($"Skipping file {relative} as it is already part of the content file");
                continue;
            }

            ImporterInfo importer = null;
            string processor = null;
            Dictionary<string, string> processorParams = null;

            // override importers
            var over = Program.GetOverrideFor(relative, overrides);
            if (over != null) {
                processorParams = over.Override.ProcessorParams;

                // copy special case
                if (over.Override.Copy) {
                    Program.CopyFile(content, relative);
                    changed = true;
                    continue;
                }

                if (!string.IsNullOrEmpty(over.Override.Importer)) {
                    importer = importers.Find(i => i.Type.Name == over.Override.Importer);
                    if (importer == null) {
                        Console.WriteLine($"Override importer {over.Override.Importer} not found for file {relative}");
                        continue;
                    }
                }

                if (!string.IsNullOrEmpty(over.Override.Processor)) {
                    processor = processors.Find(p => p == over.Override.Processor);
                    if (processor == null) {
                        Console.WriteLine($"Override processor {over.Override.Processor} not found for file {relative}");
                        continue;
                    }
                }
            }

            // normal importers
            importer ??= Program.GetImporterFor(relative, importers);
            if (importer != null && processor == null)
                processor = processors.Find(p => p == importer.Importer.DefaultProcessor);

            // no importer found :(
            if (importer == null || processor == null) {
                Console.WriteLine($"No importer or processor found for file {relative}");
                continue;
            }

            Program.AddFile(content, relative, importer.Type.Name, processor, processorParams);
            changed = true;
        }

        if (changed) {
            contentFile.Delete();
            using (var stream = contentFile.CreateText()) {
                foreach (var line in content)
                    stream.WriteLine(line);
            }
            Console.WriteLine("Wrote changes to content file");
        }
        Console.Write("Done");
    }

    private static void SafeAssemblyLoad(string refPath)
    {
        try {
            Assembly.LoadFrom(refPath);
            Console.WriteLine($"Using reference {refPath}");
        } catch (Exception e) {
            Console.WriteLine($"Error loading reference {refPath}: {e}");
        }
    }

    private static void ExtractVersions(string csprojPath, Dictionary<string, string> referencesVersions)
    {
        Console.WriteLine($"Using project file {csprojPath}");
        var projectRootElement = ProjectRootElement.Open(csprojPath);
        foreach (var property in projectRootElement.AllChildren.Where(x => x.ElementName == "PackageReference").Select(x => x as ProjectItemElement))
        {
            var libraryName = property.Include;
            if (property.Children.FirstOrDefault(x => x.ElementName == "Version") is not ProjectMetadataElement versionElement)
                continue;
            var version = versionElement.Value;
            if (referencesVersions.Keys.Contains(libraryName))
            {
                referencesVersions[libraryName] = version;
                Console.WriteLine($"Found library version for sync: {libraryName}, {version}");
            }
        }

        foreach (var library in referencesVersions)
            if (library.Value is null) 
                Console.Error.WriteLine($"Unable to find library {library.Key} in .csproj");
    }

    private static NuGetHelper _nuGetHelper;

    private static string CalculateFullPathToLibrary(string libraryName, string referencesVersion)
    {
        return Path.Combine(_nuGetHelper.PackageFolder, libraryName.ToLower(), referencesVersion, "tools", libraryName + ".dll");
    }

    private static (List<ImporterInfo>, List<string>) GetContentData() {
        var importers = new List<ImporterInfo>();
        var processors = new List<string>();
        foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies()) {
            try {
                foreach (var type in assembly.GetTypes()) {
                    var importer = (ContentImporterAttribute) type.GetCustomAttribute(typeof(ContentImporterAttribute), true);
                    if (importer != null)
                        importers.Add(new ImporterInfo(importer, type));
                    var processor = type.GetCustomAttribute(typeof(ContentProcessorAttribute), true);
                    if (processor != null)
                        processors.Add(type.Name);
                }
            } catch (Exception e) {
                Console.WriteLine($"Error gathering types in reference {assembly}: {e}");
            }
        }
        return (importers, processors);
    }

    private static IEnumerable<OverrideInfo> GetOverrides(Dictionary<string, Override> config) {
        foreach (var entry in config)
            yield return new OverrideInfo(Program.MakeFileRegex(entry.Key), entry.Value);
    }

    private static OverrideInfo GetOverrideFor(string file, IEnumerable<OverrideInfo> overrides) {
        foreach (var over in overrides) {
            if (over.Regex.IsMatch(file))
                return over;
        }
        return null;
    }

    private static ImporterInfo GetImporterFor(string file, IEnumerable<ImporterInfo> importers) {
        var extension = Path.GetExtension(file);
        foreach (var importer in importers) {
            if (importer.Importer.FileExtensions.Contains(extension))
                return importer;
        }
        return null;
    }

    private static bool HasEntry(IEnumerable<string> content, string relativeFile) {
        foreach (var line in content) {
            if (line.StartsWith($"#begin {relativeFile}"))
                return true;
        }
        return false;
    }

    private static List<string> ReadContent(FileInfo file) {
        var content = new List<string>();
        using var stream = file.OpenText();
        while (stream.ReadLine() is {} line)
            content.Add(line);
        return content;
    }

    private static void AddFile(ICollection<string> content, string relative, string importer, string processor, Dictionary<string, string> processorParams) {
        content.Add($"#begin {relative}");
        content.Add($"/importer:{importer}");
        content.Add($"/processor:{processor}");
        if (processorParams != null) {
            foreach (var kv in processorParams)
                content.Add($"/processorParam:{kv.Key}={kv.Value}");
        }
        content.Add($"/build:{relative}");
        content.Add("");
        Console.WriteLine($"Adding file {relative} with importer {importer} and processor {processor}");
    }

    private static void CopyFile(ICollection<string> content, string relative) {
        content.Add($"#begin {relative}");
        content.Add($"/copy:{relative}");
        content.Add("");
        Console.WriteLine($"Adding file {relative} with the Copy build action");
    }

    private static string GetRelativePath(string relativeTo, string path) {
        if (!relativeTo.EndsWith(Path.DirectorySeparatorChar.ToString()))
            relativeTo += Path.DirectorySeparatorChar;
        return path.Replace(relativeTo, "");
    }

    private static Regex MakeFileRegex(string s) {
        return new Regex(s.Replace(".", "[.]").Replace("*", ".*").Replace("?", "."));
    }

}