module godot.util.pregenerate;

import godot.util.classfinder;

import godot.util.tools.classes;

import std.process;
import std.stdio;
import std.string;
import std.conv : text;
import std.getopt;
import std.file;
import std.path : asRelativePath, buildPath, dirName, isRooted;
import std.range;
import std.algorithm.searching : find, endsWith, countUntil, canFind;
import std.algorithm.sorting : sort;
import std.array : replace;

enum MakeEntryPoint {
    no,
    yes,
    detect
}

enum classesFilename = "classes.csv";
enum entryPointFilename = "entrypoint.d";

enum entryPointRoot = "/// Godot-D entry point";
static immutable string entryPointSource = q{$ENTRYPOINTROOT
/// This file was automatically generated by godot-d:pregenerate.
import godot.api.register;

mixin GodotNativeLibrary!("$PREFIX");

}.replace("$ENTRYPOINTROOT", entryPointRoot);

/// Sanitize a space-separated list of absolute paths.
/// DUB's IMPORT_PATHS and STRING_IMPORT_PATHS seem to always be absolute paths.
string[] sanitized(const string paths) {
    if (paths.empty)
        return null;

    auto parts = paths.split(' ');
    if (!parts.front.isRooted)
        assert(0, "Paths passed to sanitized() are not absolute paths!");

    string[] ret;
    foreach (part; parts) {
        if (part.isRooted)
            ret ~= part;
        else
            ret[$ - 1] = ret[$ - 1] ~ " " ~ part;
    }
    return ret;
}

int main(string[] args) {
    MakeEntryPoint makeEntryPoint = MakeEntryPoint.detect;
    string prefix = environment.get("DUB_PACKAGE")
        .replace('-', '_')
        .replace(':', '_');
    auto opt = args.getopt(
        "makeEntryPoint", "Create GodotNativeLibrary entry point (if it doesn't already exist)", &makeEntryPoint,
        "prefix|p", "GDNativeLibrary symbolPrefix", &prefix
    );

    bool firstTimeSetup = false;
    void setupStart() {
        if (firstTimeSetup)
            return;
        writeln("**********************************");
        writeln("* Performing first-time setup... *");
        writeln("**********************************");
        firstTimeSetup = true;
    }

    ProjectInfo project;

    string packageDir = environment.get("DUB_PACKAGE_DIR");
    auto importPaths = environment.get("IMPORT_PATHS", null).sanitized;
    if (importPaths.empty) {
        if (exists("source"))
            importPaths ~= "source";
        else
            importPaths ~= "src";
    }

    /* ************************************************************************
	Parse all D files to find the classes and potentially the entry point.
	************************************************************************ */
    string[] sourceFiles = environment.get("SOURCE_FILES", null).sanitized;
    foreach (importPath; importPaths) {
        if (exists(importPath) && isDir(importPath)) {
            foreach (DirEntry de; dirEntries(importPath, SpanMode.depth)) {
                if (de.isFile && de.name.endsWith(".d")) {
                    if (!sourceFiles.canFind(de.name))
                        sourceFiles ~= de.name;
                }
            }
        }
    }
    foreach (sourceFile; sourceFiles) {
        /// TODO: `parse` needs to relativize the path differently. The cwd is irrelevant to Godot.
        ///       Maybe relative to DUB package or Godot project - how will it be used?
        string relativePath = sourceFile.asRelativePath(getcwd()).text;
        FileInfo file = parse(relativePath);
        writefln!"%s classes: %s"(file.moduleName, file.classes);
        project.files ~= file;
    }

    /* ************************************************************************
	Determine where to put the class list, creating a new string import folder
	if necessary.
	************************************************************************ */
    string viewsEnv = environment.get("STRING_IMPORT_PATHS");
    string classesFile;
    if (viewsEnv.empty) {
        setupStart(); // `views` will not be recognized until DUB is restarted
        string viewsDir = packageDir.buildPath("views");
        if (!exists(viewsDir)) {
            mkdirRecurse(viewsDir);
            classesFile = viewsDir.buildPath(classesFilename);
        }
    } else {
        auto splitted = viewsEnv.sanitized.sort();
        foreach (dir; splitted) {
            auto cf = dir.buildPath(classesFilename);
            if (exists(cf))
                classesFile = cf;
        }
        if (classesFile.empty) {
            string viewsDir;
            auto found = splitted.find!(d => d.endsWith("/views") || d.endsWith("/views/"));
            if (found.length)
                viewsDir = found.front;
            else
                viewsDir = splitted.front;
            classesFile = viewsDir.buildPath(classesFilename);
        }
    }

    /* ************************************************************************
	Determine where to put the entry point, if it doesn't already exist.
	Existing entry point does NOT need to be modified thanks to the class list.
	************************************************************************ */
    string entryPointFile;
    if (makeEntryPoint) {
        auto found = project.files.find!(f => f.hasEntryPoint);
        if (found.length) {
            writeln("Entry point found in ", found.front.name);
            // re-generate it if it is the auto-generated one, in case the prefix was changed.
            // TODO: detect based on content, not name
            if (found.front.name.endsWith("entrypoint.d"))
                entryPointFile = found.front.name;
        } else {
            entryPointFile = importPaths.front.buildPath(entryPointFilename);
            if (entryPointFile.exists)
                assert(0, entryPointFile ~ " exists but does not contain the GodotNativeLibrary mixin.");
        }
    }

    /* ************************************************************************
	Write necessary files
	************************************************************************ */
    if (makeEntryPoint && entryPointFile) {
        string entryPointText = entryPointSource
            .replace("$PREFIX", prefix);
        writeln("Writing entry point to ", entryPointFile);
        std.file.write(entryPointFile, entryPointText);
    }
    writeln("Writing class list to ", classesFile);
    std.file.write(classesFile, project.toCsv);
    string gdignore = classesFile.dirName.buildPath(".gdignore");
    if (!gdignore.exists)
        std.file.write(gdignore, "");

    if (firstTimeSetup) {
        writeln("*******************************************************");
        writeln("* DUB must be restarted to complete first-time setup. *");
        writeln("* This will only be necessary once.                   *");
        writeln("*******************************************************");
        return 2;
    }

    return 0;
}