#!/usr/bin/env dub
/+ dub.sdl:
	name "openapigenerator.d"
	dependency "dyaml" version="~>0.8.0"
    dependency "handlebars" version="~>0.2.2"
    stringImportPaths "codegen"
+/

// The following copyright string also applies to this file.
string COPYRIGHT = q"EOL
/*
 * Sailfin: a Jellyfin client written using Qt
 * Copyright (C) 2021 Chris Josten and the Sailfin Contributors.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
EOL";
import std.algorithm;
import std.array;
import std.file : mkdirRecurse;
import std.exception;
import std.path : buildPath, dirSeparator;
import std.range;
import std.string;
import std.stdio;
import std.uni;

import dyaml;
import handlebars.tpl;

static this() {
	COPYRIGHT ~= q"EOS
/*
 * WARNING: THIS IS AN AUTOMATICALLY GENERATED FILE! PLEASE DO NOT EDIT THIS, AS YOUR EDITS WILL GET
 * OVERWRITTEN AT SOME POINT! 
 *
 * If there is a bug in this file, please fix the code generator used to generate this file found in
 * core/openapigenerator.d. 
 *
 * This file is generated based on Jellyfin's OpenAPI description, "openapi.json". Please update that
 * file with a newer file if needed instead of manually updating the files.
 */
EOS";
}

// CODE GENERATION SETTINGS

// File name of the CMake file this generated should generate.
string CMAKE_INCLUDE_FILE = "GeneratedSources.cmake";
string CMAKE_VAR_PREFIX = "openapi";


string INCLUDE_PREFIX = "JellyfinQt";
string SRC_PREFIX = "";

string MODEL_FOLDER = "DTO";
string SUPPORT_FOLDER = "support";

string[string] compatAliases;
string[string] memberAliases;

static this() {
	compatAliases["BaseItemDto"] = "Item";
	compatAliases["UserDto"] = "User";
	compatAliases["UserItemDataDto"] = "UserData";
	
	memberAliases["id"] = "jellyfinId";
}

CasePolicy OPENAPI_CASING = CasePolicy.PASCAL;
static immutable string[1] CPP_NAMESPACE = ["Jellyfin"];
static immutable string[2] CPP_NAMESPACE_DTO = ["Jellyfin", "DTO"];
static immutable string[2] CPP_NAMESPACE_SUPPORT = ["Jellyfin", "Support"];

CasePolicy CPP_FILENAME_CASING = CasePolicy.LOWER;
CasePolicy CPP_CLASS_CASING = CasePolicy.PASCAL;
CasePolicy CPP_CLASS_MEMBER_CASING = CasePolicy.CAMEL;
// Prefix for class members.
string CPP_CLASS_MEMBER_PREFIX = "m_";
CasePolicy CPP_CLASS_METHOD_CASING = CasePolicy.CAMEL;
bool GENERATE_PROPERTIES = true;

string outputDirectory = "generated";
// END CODE GENERATION SETTINGS.

// Implementation

enum CasePolicy {
	KEEP, // Do not modify
	PASCAL, // PascalCase
	CAMEL, // camelCase
	SNAKE, // snake_case
	SCREAMING_SNAKE, // SCREAMING_SNAKE_CASE
	LOWER, // lowercase
	UPPER // UPPERCASE
}

string USAGE = "USAGE: %s <openapi scheme>";

class CLIArgumentException : Exception {
	mixin basicExceptionCtors;
}

int main(string[] args) {
	try {
		realMain(args);
	} catch (CLIArgumentException e) {
		stderr.writeln(e.message);
		return -1;
	}
	return 0;
}

void realMain(string[] args) {
	enforce!CLIArgumentException(args.length >= 2, USAGE.format(args[0]));
	string schemeFile = args[1];
	
	if (args.length >= 3) outputDirectory = args[2];
	mkdirRecurse(buildPath(outputDirectory, "include", INCLUDE_PREFIX, MODEL_FOLDER));
	mkdirRecurse(buildPath(outputDirectory, "src", SRC_PREFIX, MODEL_FOLDER));
	
	Node root = Loader.fromFile(schemeFile).load();
	Appender!(string[]) headerFiles, implementationFiles;
	foreach(string key, ref const Node scheme; root["components"]["schemas"]) {
		generateFileForSchema(key, scheme, root["components"]["schemas"]);
		
		string fileBase = key.applyCasePolicy(OPENAPI_CASING, CPP_FILENAME_CASING);
		headerFiles ~= [buildPath(outputDirectory, "include", INCLUDE_PREFIX, MODEL_FOLDER, fileBase ~ ".h")];
		implementationFiles ~= [buildPath(outputDirectory, "src", SRC_PREFIX, MODEL_FOLDER, fileBase ~ ".cpp")];
	}
	foreach(string original, string compatAlias; compatAliases) {
		writeCompatAliasFile(original, compatAlias);
	}
	writeCMakeFile(headerFiles[], implementationFiles[]);
}

void writeCMakeFile(string[] headerFiles, string[] implementationFiles) {
	File output = File(buildPath(outputDirectory, CMAKE_INCLUDE_FILE), "w+");
	output.writeln("cmake_minimum_required(VERSION 3.0)");
	// Peek laziness: wrapping a C++ comment inside a CMake block comment because I couldn't be
	// donkey'd to do otherwise.
	output.writeln("#[[");
	output.writeln(COPYRIGHT);
	output.writeln("]]");
	
	output.writef("set(%s_HEADERS", CMAKE_VAR_PREFIX);
	foreach (headerFile; headerFiles) {
		output.writeln();
		output.writef("\t%s", headerFile);
	}
	output.writeln(")");
	output.writeln();
	
	output.writef("set(%s_SOURCES", CMAKE_VAR_PREFIX);
	foreach (implementationFile; implementationFiles) {
		output.writeln();
		output.writef("\t%s", implementationFile);
	}
	output.writeln(")");
}

void writeCompatAliasFile(ref const string original, ref const string compatAlias) {
	string fileBase = compatAlias.applyCasePolicy(OPENAPI_CASING, CPP_FILENAME_CASING);
	File headerFile = File(buildPath(outputDirectory, "include", INCLUDE_PREFIX, MODEL_FOLDER, fileBase ~ ".h"), "w+");
	File implementationFile = File(buildPath(outputDirectory, "src", SRC_PREFIX, MODEL_FOLDER, fileBase ~ ".cpp"), "w+");
	
	writeHeaderPreamble(headerFile, CPP_NAMESPACE_DTO, compatAlias, [], [original]);
	headerFile.writefln("using %s = %s;", compatAlias, original);
	writeHeaderPostamble(headerFile, CPP_NAMESPACE_DTO, compatAlias);
}

void generateFileForSchema(ref string name, ref const Node scheme, Node allSchemas) {
	string fileBase = name.applyCasePolicy(OPENAPI_CASING, CPP_FILENAME_CASING);
	File headerFile = File(buildPath(outputDirectory, "include", INCLUDE_PREFIX, MODEL_FOLDER, fileBase ~ ".h"), "w+");
	File implementationFile = File(buildPath(outputDirectory, "src", SRC_PREFIX, MODEL_FOLDER, fileBase ~ ".cpp"), "w+");
	
	if ("enum" in scheme) {
		string[3] imports = ["QJsonValue", "QObject", "QString"];
		string[1] userImports = [buildPath(SUPPORT_FOLDER, "jsonconv.h")];
		writeHeaderPreamble(headerFile, CPP_NAMESPACE_DTO, name, imports, userImports);
		
		Appender!(string[]) values;
		foreach (string value; scheme["enum"]) {
			values ~= value;
		}
		writeEnumHeader(headerFile, name, values[]);
		writeHeaderPostamble(headerFile, CPP_NAMESPACE_DTO, name);
		
		writeImplementationPreamble(implementationFile, CPP_NAMESPACE_DTO, name);
		writeEnumImplementation(implementationFile, name);
		writeImplementationPostamble(implementationFile, CPP_NAMESPACE_DTO, name);
	}
	if (scheme["type"].as!string == "object" && "properties" in scheme) {
		// Determine all imports
		Appender!(string[]) systemImports, userImports;
		Appender!(string[]) forwardDeclarations;
		systemImports ~= ["optional", "QJsonObject", "QJsonValue"];
		userImports ~= [buildPath(SUPPORT_FOLDER, "jsonconv.h")];
		
		MetaTypeInfo[] usedTypes = collectTypeInfo(scheme["properties"], allSchemas);
		bool importedContainers = false;
		void collectImports(MetaTypeInfo type) {
			if (type.needsPointer && !systemImports[].canFind("QSharedPointer")) {
				systemImports ~= ["QSharedPointer"];
			}
			
			if (type.needsSystemImport && !systemImports[].canFind(type.typeName)) {
				if (type.isContainer) {
					if (!importedContainers) {
						systemImports ~= ["QList", "QStringList"];
						importedContainers = true;
					}
					if (type.containerType !is null) {
						collectImports(type.containerType);
					}
				} else {
					systemImports ~= [type.typeName];
				}
			} else {
				string userImport = buildPath(MODEL_FOLDER, type.typeName.applyCasePolicy(OPENAPI_CASING, CasePolicy.LOWER) ~ ".h");
				if (type.needsLocalImport && !userImports[].canFind(userImport) && type.typeName != name) {
					userImports ~= userImport;
				}
			}
		}
		foreach (type; usedTypes) {
			collectImports(type);
		}
		
		// Sort them for nicer reading
		string[] sortedSystemImports = sort(systemImports[]).array;
		string[] sortedUserImports = sort(userImports[]).array;
		string[] sortedForwardDeclarations = sort(forwardDeclarations[]).array;
		
		// Write implementation files
		writeHeaderPreamble(headerFile, CPP_NAMESPACE_DTO, name, sortedSystemImports, sortedUserImports);
		writeObjectHeader(headerFile, name, usedTypes, sortedForwardDeclarations);
		writeHeaderPostamble(headerFile, CPP_NAMESPACE_DTO, name);
		
		writeImplementationPreamble(implementationFile, CPP_NAMESPACE_DTO, name);
		writeObjectImplementation(implementationFile, name, usedTypes);
		writeImplementationPostamble(implementationFile, CPP_NAMESPACE_DTO, name);
	}
}

// Object
MetaTypeInfo[] collectTypeInfo(Node properties, Node allSchemas) {

	// We need to recurse (sometimes)
	MetaTypeInfo getType(string name, Node node) {
		MetaTypeInfo info = new MetaTypeInfo();
		info.originalName = name;
		info.name = name.applyCasePolicy(OPENAPI_CASING, CPP_CLASS_MEMBER_CASING);
		if ("description" in node) {
			info.description = node["description"].as!string;
		}
		
		// Special case for QML
		info.name = memberAliases.get(info.name.toLower(), info.name);
		
		if ("$ref" in node) {
			string type = node["$ref"].as!string()["#/components/schemas/".length..$];
			if (type in allSchemas&& "type" in allSchemas[type] 
					&& allSchemas[type]["type"].as!string == "object") {
				info.needsPointer = true;
				info.isTypeNullable = true;
				info.typeNullableCheck = ".isNull()";
				info.typeNullableSetter = ".clear()";
			}

			info.needsLocalImport = true;
			info.typeName = type; 
			return info;
		}
		if (!("type" in node)) {
			info.typeName = "QVariant";
			info.isTypeNullable = true;
			info.needsSystemImport = true;
			info.typeNullableCheck = ".isNull()";
			info.typeNullableSetter = ".clear()";
			return info;
		}
		switch(node["type"].as!string) {
		case "boolean":
			info.typeName = "bool";
			return info;
		case "string":
			if ("format" in node) {
				switch(node["format"].as!string) {
				case "date-time":
					info.typeName= "QDateTime";
					info.needsSystemImport = true;
					info.isTypeNullable = true;
					info.typeNullableCheck = ".isNull()";
					info.typeNullableSetter = "= QDateTime()";
					return info;
				case "uuid":
					info.typeName = "QUuid";
					info.needsSystemImport = true;
					info.isTypeNullable = true;
					info.typeNullableCheck = ".isNull()";
					info.typeNullableSetter = "= QGuid()";
					return info;
				default:
					break;
				}
			}
			info.isTypeNullable = true;
			info.typeName= "QString";
			info.needsSystemImport = true;
			info.typeNullableCheck = ".isNull()";
			info.typeNullableSetter = ".clear()";
			return info;
		case "integer":
			if ("format" in node) {
				info.typeName= "q" ~ node["format"].as!string;
				return info;
			}
			goto default;
		case "number":
			if ("format" in node) {
				switch(node["format"].as!string) {
				case "float":
				case "double":
					info.typeName = node["format"].as!string;
					return info;
				default:
					break;
				}
			}
			goto default;
		case "object":
			info.typeName = "QJsonObject"; // This'll do for now
			return info;
		case "array":
			MetaTypeInfo containedType = getType("arrayItem", node["items"]);
			info.needsLocalImport = containedType.needsLocalImport;
			info.needsSystemImport = true;
			info.isContainer = true;
			info.containerType = containedType;
			info.isTypeNullable = true;
			info.typeNullableCheck = ".size() == 0";
			info.typeNullableSetter = ".clear()";
			if (containedType.typeName == "QString") {
				info.typeName = "QStringList";
			} else {
				info.typeName = "QList<" ~ containedType.typeNameWithQualifiers ~ ">";
			}
			return info;
		default:
			info.typeName = "UNIMPLEMENTED";
			return info;
		}
	}
	
	Appender!(MetaTypeInfo[]) result;
	
	foreach(const ref string name, const ref Node node; properties) {
		result ~= getType(name, node);
	}
	return result[];
}

void writeObjectHeader(File output, string name, MetaTypeInfo[] properties, string[] userImports) {
	class Controller {
		string className;
		MetaTypeInfo[] properties;
		string[] userImports;
		string supportNamespace = namespaceString!CPP_NAMESPACE_SUPPORT;
	}
	Controller controller = new Controller();
	controller.className = name.applyCasePolicy(OPENAPI_CASING, CPP_CLASS_CASING);
	controller.properties = properties;
	controller.userImports = userImports;
	
	output.writeln(render!(import("object_header.hbs"), Controller)(controller));
	
	
}

void writeObjectImplementation(File output, string name, MetaTypeInfo[] properties) {
	class Controller {
		string className;
		MetaTypeInfo[] properties;
		string supportNamespace = namespaceString!CPP_NAMESPACE_SUPPORT;
	}
	Controller controller = new Controller();
	controller.className = name.applyCasePolicy(OPENAPI_CASING, CPP_CLASS_CASING);
	controller.properties = properties;
	output.writeln(render!(import("object_implementation.hbs"), Controller)(controller));
}

// Enum
void writeEnumHeader(File output, string name, string[] values, string doc = "") {
	class Controller {
		string className;
		string[] values;
		string supportNamespace = namespaceString!CPP_NAMESPACE_SUPPORT;
	}
	Controller controller = new Controller();
	controller.className = name.applyCasePolicy(OPENAPI_CASING, CPP_CLASS_CASING);
	controller.values = values;
	output.writeln(render!(import("enum_header.hbs"), Controller)(controller));
}

void writeEnumImplementation(File output, string name) {
	string className = name.applyCasePolicy(OPENAPI_CASING, CPP_CLASS_CASING);
	output.writefln("%sClass::%sClass() {}", name, name);
}

// Common
void writeHeaderPreamble(File output, immutable string[] fileNamespace, string className, string[] imports = [], string[] userImports = []) {
	output.writeln(COPYRIGHT);
	string guard = guardName(fileNamespace, className);
	output.writefln("#ifndef %s", guard);
	output.writefln("#define %s", guard);
	output.writeln();
	
	foreach(file; imports) {
		output.writefln("#include <%s>", file);
	}
	
	if (imports.length > 0) output.writeln();
	
	foreach(file; userImports) {
		output.writefln("#include \"%s\"", buildPath(INCLUDE_PREFIX, file));
	}
	if (userImports.length > 0) output.writeln();
	
	foreach (namespace; fileNamespace) {
		output.writefln("namespace %s {", namespace);
	}
	output.writeln();
}

void writeHeaderPostamble(File output, immutable string[] fileNamespace, string className) {
	output.writeln();
	foreach(namespace; fileNamespace) {
		output.writefln("} // NS %s", namespace);
	}
	output.writeln();
	output.writefln("#endif // %s", guardName(fileNamespace, className));
}

void writeImplementationPreamble(File output, immutable string[] fileNamespace, string className, string[] imports = []) {
	output.writeln(COPYRIGHT);
	output.writefln("#include <%s>", buildPath(INCLUDE_PREFIX, MODEL_FOLDER, className.applyCasePolicy(OPENAPI_CASING, CasePolicy.LOWER) ~ ".h"));
	output.writeln();
	
	foreach(file; imports) {
		output.writefln("#include <%s>", buildPath(INCLUDE_PREFIX, file));
	}
	if (imports.length > 0) output.writeln();
	
	foreach (namespace; fileNamespace) {
		output.writefln("namespace %s {", namespace);
	}
	output.writeln();
}

void writeImplementationPostamble(File output, immutable string[] fileNamespace, string className) {
	output.writeln();
	foreach(namespace; fileNamespace) {
		output.writefln("} // NS %s", namespace);
	}
}


// Helper functions
string applyCasePolicy(string source, CasePolicy input, CasePolicy output) {
	if (input == output)  return source;
	switch(output) {
	case CasePolicy.KEEP:
		return source;
	case CasePolicy.PASCAL:
		if (input == CasePolicy.CAMEL) {
			char[] result = source.dup;
			result[0] = cast(char) toUpper(result[0]);
			return cast(string) result;
		} else {
			throw new Exception("Not implemented");
		}
	case CasePolicy.CAMEL:
		if (input == CasePolicy.PASCAL) {
			char[] result = source.dup;
			result[0] = cast(char) toLower(result[0]);
			return cast(string) result;
		} else {
			throw new Exception("Not implemented");
		}
	case CasePolicy.LOWER:
		if (input == CasePolicy.CAMEL || input == CasePolicy.PASCAL) {
			return source.toLower();
		}
		throw new Exception("Not implemented");
	case CasePolicy.UPPER:
		if (input == CasePolicy.CAMEL || input == CasePolicy.PASCAL) {
			return source.toUpper();
		}
		throw new Exception("Not implemented");
	case CasePolicy.SCREAMING_SNAKE:
		if (input == CasePolicy.CAMEL || input == CasePolicy.PASCAL) {
			char[] mutableSource = source.dup;
			Appender!(char[]) result;
			foreach(window; source.slide!(Yes.withPartial)(2)) {
				dchar c = window.front;
				window.popFront();
				dchar n = window.front;
				if (isLower(c) && !isLower(n)) {
					result ~= toUpper(c);
					result ~= '_';
				} else if (!isLower(c) && !isLower(n)) {
					result ~= toUpper(c);
				} else {
					result ~= toUpper(c);
				} 
			}
			result ~= toUpper(source[$ - 1]);
			return cast(string) result[];
		}
		throw new Exception("Not implemented");
	default:
		throw new Exception("Not implemented");
	}
}

class MetaTypeInfo {
public:
	string originalName = "";
	string name = "";
	string typeName = "";
	/// Description of this property.
	string description = "";
	/// If this property is nullable according to the OpenAPI spec.
	bool isNullable = false;
	bool needsPointer = false;
	/// If the type needs a system import (Such as Qt types)
	bool needsSystemImport = false;
	/// If the type needs a local import (such as types elsewhere in this project).
	bool needsLocalImport = false;
	/// If the type is a container type
	bool isContainer = false;
	/// If this type has a non-ambigious null state.
	bool isTypeNullable = false;
	/// If `isContainer` is true, the type of the container.
	MetaTypeInfo containerType = null;
	
	string writeName() {
		return name.applyCasePolicy(CPP_CLASS_MEMBER_CASING, CasePolicy.PASCAL);
	}
	
	string memberName() {
		return CPP_CLASS_MEMBER_PREFIX ~ name;
	}
	
	string typeNameWithQualifiers() {
		if (needsPointer) {
			return "QSharedPointer<" ~ typeName~ ">";
		} else {
			return typeName;
		}
	}
	
	bool needsOptional() {
		return isNullable && !isTypeNullable;
	}
	
	string typeNullableCheck;
	string nullableCheck() {
		if (typeNullableCheck.length > 0) {
			return memberName ~ "." ~ typeNullableCheck;
		}
		if (needsOptional) {
			return "!" ~ memberName ~ ".has_value()";
		}
		return "Q_ASSERT(false)";
	}
	
	string typeNullableSetter = "";
	string nullableSetter() {
		if (needsOptional) {
			return memberName ~ "= std::nullopt";
		}
		if (typeNullableSetter.startsWith("=")) {
			return memberName ~ typeNullableSetter;
		} else {
			return typeNullableSetter;
		}
	}
	
	string defaultInitializer() {
		if (needsPointer) return "nullptr";
		if (needsOptional) return "std::nullopt";
		return "";
	}
}

string guardName(immutable string[] namespace, string className) {
	return namespace.map!toUpper().join("_") ~ "_"
		~ className.applyCasePolicy(OPENAPI_CASING, CasePolicy.UPPER)
		~ "_H";
}

string namespaceString(string[] name)() {
	string result;
	static foreach(idx, part; name) {
		static if (idx != 0) {
			result ~= "::";
		}
		result ~= part;
	}
	return result;
}