using System.Diagnostics;
using System.Reflection;
using CLI;
using Generation.QBE;
using Syntax;
using Syntax.Parsing;
using Syntax.Tokenization;
using Syntax.Typing;

const string BIN_DIR = "bin";
const string BIN_INT_DIR = "bin-int";

if (Directory.Exists(BIN_DIR))
{
    Directory.Delete(BIN_DIR, true);
}

if (Directory.Exists(BIN_INT_DIR))
{
    Directory.Delete(BIN_INT_DIR, true);
}

Directory.CreateDirectory(BIN_DIR);
Directory.CreateDirectory(BIN_INT_DIR);

var error = false;
var compilationUnits = new List<CompilationUnit>();
var sourceTexts = new Dictionary<CompilationUnit, SourceText>();

foreach (var file in args)
{
    if (!File.Exists(file))
    {
        Console.Error.WriteLine($"File '{file}' does not exist");
        return 1;
    }

    var content = File.ReadAllText(file);

    var sourceText = new SourceText(file, content);

    var tokenizeResult = Tokenizer.Tokenize(sourceText);
    tokenizeResult.PrintAllDiagnostics();
    error = error || tokenizeResult.HasErrors;

    var parseResult = Parser.ParseFile(tokenizeResult.Value);
    parseResult.PrintAllDiagnostics();
    error = error || parseResult.HasErrors;

    if (parseResult.Value != null)
    {
        compilationUnits.Add(parseResult.Value);
        sourceTexts[parseResult.Value] = sourceText;
    }
}

if (error)
{
    return 1;
}

var definitionTable = new DefinitionTable(compilationUnits);

foreach (var compilationUnit in compilationUnits)
{
    var typeCheckResult = TypeChecker.Check(compilationUnit, definitionTable);
    typeCheckResult.PrintAllDiagnostics();
    error = error || typeCheckResult.HasErrors;
}

if (error)
{
    return 1;
}

var objectFiles = new List<string>();

foreach (var compilationUnit in compilationUnits)
{
    var relativeFilePath = Path.GetRelativePath(Environment.CurrentDirectory, sourceTexts[compilationUnit].Path);
    var outputPath = Path.Combine(BIN_INT_DIR, "program", relativeFilePath);

    var outputDirectory = Path.GetDirectoryName(outputPath);
    Debug.Assert(!string.IsNullOrWhiteSpace(outputDirectory));
    Directory.CreateDirectory(outputDirectory);
    
    var ssa = QBEGenerator.Emit(compilationUnit, definitionTable);
    var ssaPath = Path.ChangeExtension(outputPath, "ssa"); 
    File.WriteAllText(ssaPath, ssa);
    
    var asm = await QBE.Invoke(ssa);
    if (asm == null)
    {
        return 1;
    }

    var asmPath = Path.ChangeExtension(outputPath, "s");
    await File.WriteAllTextAsync(asmPath, asm);

    var objPath = Path.ChangeExtension(outputPath, "o");
    var asmSuccess = await GCC.Assemble(asmPath, objPath);
    if (!asmSuccess)
    {
        return 1;
    }

    objectFiles.Add(objPath);
}

var assembly = Assembly.GetExecutingAssembly();
var runtimeResources = assembly
    .GetManifestResourceNames()
    .Where(name => name.EndsWith(".s", StringComparison.OrdinalIgnoreCase));

foreach (var resourceName in runtimeResources)
{
    await using var stream = assembly.GetManifestResourceStream(resourceName);
    if (stream == null)
    {
        Console.Error.WriteLine($"Could not load embedded resource {resourceName}");
        return 1;
    }

    using var reader = new StreamReader(stream);
    var asm = await reader.ReadToEndAsync();

    var outputDirectory = Path.Combine(BIN_INT_DIR, "runtime");
    Directory.CreateDirectory(outputDirectory);

    var fileName = resourceName.Split('.').Reverse().Skip(1).First();

    var asmPath = Path.Combine(outputDirectory, fileName + ".s");
    await File.WriteAllTextAsync(asmPath, asm);

    var objPath = Path.Combine(outputDirectory, fileName + ".o");
    var asmSuccess = await GCC.Assemble(asmPath, objPath);
    if (!asmSuccess)
    {
        return 1;
    }

    objectFiles.Add(objPath);
}

var linkSuccess = await GCC.Link(objectFiles, Path.Combine(BIN_DIR, "out"));
return linkSuccess ? 0 : 1;