package me.djmm.java.code_analysis;

import java.net.URI;

import java.util.Objects;

import java.util.regex.Pattern;

/**

* Immutable representation of a source file's content, identified by URI.

*

* <p>URIs should follow a path convention matching the Java package structure. For in-memory

* sources, use the {@code mem} scheme (e.g., {@code mem:///com/example/Foo.java}).

*

* @param uri Unique identifier for this source file.

* @param content The full source text.

* @param version Monotonically increasing version number for change tracking. Use 0 for unversioned

* sources.

*/

public record SourceText(URI uri, String content, long version) {

private static final Pattern PACKAGE_PATTERN =

Pattern.compile("^\\s*package\\s+([\\w.]+)\\s*;", Pattern.MULTILINE);

public SourceText {

Objects.requireNonNull(uri, "uri");

Objects.requireNonNull(content, "content");

if (version < 0) {

throw new IllegalArgumentException("version must be non-negative");

}

}

/**

* Create a source text with a {@code mem:///} URI and version 0.

*

* @param path Path portion of the URI, e.g. {@code "com/example/Foo.java"}.

* @param content The Java source code.

*/

public static SourceText of(String path, String content) {

Objects.requireNonNull(path, "path");

// Strip leading slash if present to avoid double slashes

var normalised = path.startsWith("/") ? path.substring(1) : path;

return new SourceText(URI.create("mem:///" + normalised), content, 0);

}

/**

* Extracts the package name declared in this source. Returns the empty string for the default

* (unnamed) package.

*/

public String packageName() {

return extractPackageName(content);

}

/**

* Derives the simple class name from the URI's file name. For example, {@code

* mem:///com/example/Foo.java} yields {@code "Foo"}.

*/

public String simpleClassName() {

var path = uri.getPath();

if (path == null) {

return "";

}

var lastSlash = path.lastIndexOf('/');

var fileName = lastSlash >= 0 ? path.substring(lastSlash + 1) : path;

var dot = fileName.lastIndexOf('.');

return dot >= 0 ? fileName.substring(0, dot) : fileName;

}

/**

* Derives the binary name (fully-qualified class name) from the package declaration and URI file

* name. For example, a source with {@code package com.example;} at URI {@code

* mem:///com/example/Foo.java} yields {@code "com.example.Foo"}.

*/

public String binaryName() {

var pkg = packageName();

var simpleName = simpleClassName();

return pkg.isEmpty() ? simpleName : pkg + "." + simpleName;

}

/**

* Extract the package name from Java source content. Returns the empty string for the default

* (unnamed) package.

*/

public static String extractPackageName(String source) {

var matcher = PACKAGE_PATTERN.matcher(source);

return matcher.find() ? matcher.group(1) : "";

}

}