using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text.RegularExpressions;
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();

        // load any references to be able to include custom content types as well
        foreach (var line in content) {
            if (!line.StartsWith("/reference:"))
                continue;
            var reference = line.Substring(11);
            var refPath = Path.GetFullPath(Path.Combine(contentFile.DirectoryName, reference));
            try {
                Assembly.LoadFrom(refPath);
                Console.WriteLine($"Using reference {refPath}");
            } catch (Exception e) {
                Console.WriteLine($"Error loading reference {refPath}: {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)}");

        var changed = false;
        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 (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("?", "."));
    }

}