package org.zwobble.hobgoblin.compiler;

import org.zwobble.hobgoblin.compiler.ast.untyped.UntypedNamespaceNode;
import org.zwobble.hobgoblin.compiler.builtins.NativeTypes;
import org.zwobble.hobgoblin.compiler.config.ProjectConfig;
import org.zwobble.hobgoblin.compiler.parser.Parser;
import org.zwobble.hobgoblin.compiler.typechecker.TypeChecker;
import org.zwobble.hobgoblin.compiler.typechecker.TypeCheckerGlobalContext;
import org.zwobble.hobgoblin.compiler.types.NamespaceName;
import org.zwobble.sourcetext.SourceText;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.ArrayList;
import java.util.List;

public class HobgoblinCompiler {
    public static final String FILE_NAME_EXTENSION = ".hob";

    private HobgoblinCompiler() {
    }

    public static void compile(Path projectRoot) throws IOException {
        var config = ProjectConfig.read(projectRoot);
        var generators = config.createGenerators();

        var sourceDirectory = projectRoot.resolve("src");

        var sourceFiles = collectSourceFiles(sourceDirectory);

        var untypedNamespaceNodes = new ArrayList<UntypedNamespaceNode>();
        for (var sourceFile : sourceFiles) {
            var namespaceName = sourceFileNamespaceName(sourceDirectory, sourceFile);
            var sourceContents = Files.readString(sourceFile, StandardCharsets.UTF_8);
            var sourceText = SourceText.fromString(sourceFile.toString(), sourceContents);
            var untypedNamespaceNode = Parser.parseNamespace(sourceText, namespaceName);
            untypedNamespaceNodes.add(untypedNamespaceNode);
        }

        var typeCheckerContext = TypeCheckerGlobalContext.initial();
        typeCheckerContext.addNativeType(NativeTypes.BOOL);
        typeCheckerContext.addNativeType(NativeTypes.FLOAT_64);
        typeCheckerContext.addNativeType(NativeTypes.INT_8);
        typeCheckerContext.addNativeType(NativeTypes.INT_32);
        typeCheckerContext.addNativeType(NativeTypes.INT_64);
        typeCheckerContext.addNativeType(NativeTypes.STRING);
        typeCheckerContext.addNativeTypeConstructor(NativeTypes.BOX);
        typeCheckerContext.addNativeTypeConstructor(NativeTypes.LIST);
        typeCheckerContext.addNativeTypeConstructor(NativeTypes.OPTION);
        typeCheckerContext.addNativeTypeConstructor(NativeTypes.SHARED);

        var typedNamespaceNodes = TypeChecker.typeCheckNamespaces(untypedNamespaceNodes, typeCheckerContext);

        var typesInfo = typeCheckerContext.toTypesInfo();

        for (var generator : generators) {
            generator.generate(typedNamespaceNodes, typesInfo);
        }
    }

    static NamespaceName sourceFileNamespaceName(Path sourceDirectory, Path sourceFilePath) {
        var relativePath = sourceDirectory.relativize(sourceFilePath);

        var parts = new ArrayList<String>();
        for (var i = 0; i < relativePath.getNameCount() - 1; i++) {
            parts.add(relativePath.getName(i).toString());
        }

        var fileName = relativePath.getName(relativePath.getNameCount() - 1).toString();
        var lastPart = fileName.substring(0, fileName.length() - FILE_NAME_EXTENSION.length());
        parts.add(lastPart);

        return new NamespaceName(parts);
    }

    private static List<Path> collectSourceFiles(
        Path sourceRoot
    ) throws IOException {
        var sourceFiles = new ArrayList<Path>();

        Files.walkFileTree(sourceRoot, new SimpleFileVisitor<Path>() {
            @Override
            public FileVisitResult visitFile(
                Path file,
                BasicFileAttributes attrs
            ) {
                if (file.toString().endsWith(FILE_NAME_EXTENSION)) {
                    sourceFiles.add(file);
                }
                return FileVisitResult.CONTINUE;
            }

            @Override
            public FileVisitResult postVisitDirectory(
                Path dir,
                IOException exc
            ) {
                return FileVisitResult.CONTINUE;
            }
        });
        sourceFiles.sort(null);
        return sourceFiles;
    }
}