use std::io::{Read,Seek};
use clap::{Args,Parser,Subcommand};
use anyhow::Result as AResult;
use futures::StreamExt;
use rbx_dom_weak::types::Ref;

type AssetID=u64;
type AssetIDFileMap=Vec<(AssetID,std::path::PathBuf)>;
const CONCURRENT_REQUESTS:usize=8;

/// Parse a single key-value pair
fn parse_key_val<T,U>(s:&str)->AResult<(T,U)>
where
	T:std::str::FromStr,
	T::Err:std::error::Error+Send+Sync+'static,
	U:std::str::FromStr,
	U::Err:std::error::Error+Send+Sync+'static,
{
	let pos=s
		.find('=')
		.ok_or_else(||anyhow::Error::msg(format!("invalid KEY=value: no `=` found in `{s}`")))?;
	Ok((s[..pos].parse()?,s[pos+1..].parse()?))
}

#[derive(Parser)]
#[command(author,version,about,long_about=None)]
#[command(propagate_version = true)]
struct Cli{
	#[arg(short,long)]
	group:Option<u64>,
	//idk how to do this better
	#[arg(long)]
	cookie_literal:Option<String>,
	#[arg(long)]
	cookie_env:Option<String>,
	#[arg(long)]
	cookie_file:Option<std::path::PathBuf>,

	#[arg(long,value_parser=parse_key_val::<AssetID,std::path::PathBuf>)]
	asset_id:Option<(AssetID,std::path::PathBuf)>,

	#[arg(short,long)]
	input:Option<std::path::PathBuf>,

	#[arg(short,long)]
	output:Option<std::path::PathBuf>,

	#[command(subcommand)]
	command:Commands,
}

#[derive(Subcommand)]
enum Commands{
	Download,
	Upload,
	Compile,
	Decompile,
}

#[derive(Args)]
struct PathBufList{
	paths:Vec<std::path::PathBuf>
}

#[tokio::main]
async fn main()->AResult<()>{
	let cli=Cli::parse();

	let cookie_enum={
		match (cli.cookie_literal,cli.cookie_env,cli.cookie_file){
			(Some(literal),None,None)=>Some(Cookie::Literal(literal)),
			(None,Some(env_var),None)=>Some(Cookie::Environment(env_var)),
			(None,None,Some(path))=>Some(Cookie::File(path)),
			(None,None,None)=>None,
			_=>return Err(anyhow::Error::msg("Cookie was specified multiple times.")),
		}
	};
	let cookie=match cookie_enum{
		Some(c)=>Some(format!(".ROBLOSECURITY={}",match c{
			Cookie::Literal(s)=>s,
			Cookie::Environment(var)=>std::env::var(var)?,
			Cookie::File(path)=>tokio::fs::read_to_string(path).await?,
		})),
		None=>None,
	};

	match cli.command{
		Commands::Download=>download_list(cookie.unwrap(),vec![cli.asset_id.unwrap()]).await,
		Commands::Upload=>upload_list(cookie.unwrap(),cli.group,vec![cli.asset_id.unwrap()]).await,
		Commands::Compile=>compile(cli.input.unwrap(),cli.output.unwrap()),
		Commands::Decompile=>decompile(cli.input.unwrap(),cli.output.unwrap()),
	}
}

enum Cookie{
	Literal(String),
	Environment(String),
	File(std::path::PathBuf),
}

enum ReaderType<'a,R:Read+Seek>{
	GZip(flate2::read::GzDecoder<&'a mut R>),
	Raw(&'a mut R),
}

fn maybe_gzip_decode<R:Read+Seek>(input:&mut R)->AResult<ReaderType<R>>{
	let mut first_2=[0u8;2];
	if let (Ok(()),Ok(()))=(std::io::Read::read_exact(input,&mut first_2),std::io::Seek::rewind(input)){
		match &first_2{
			b"\x1f\x8b"=>Ok(ReaderType::GZip(flate2::read::GzDecoder::new(input))),
			_=>Ok(ReaderType::Raw(input)),
		}
	}else{
		Err(anyhow::Error::msg("failed to peek"))
	}
}

async fn upload_list(cookie:String,group:Option<u64>,asset_id_file_map:AssetIDFileMap)->AResult<()>{
	let client=reqwest::Client::new();
	futures::stream::iter(asset_id_file_map)
	.map(|(asset_id,file)|{
		let client=&client;
		let cookie=cookie.as_str();
		let group=&group;
		async move{
			let mut url=reqwest::Url::parse("https://data.roblox.com/Data/Upload.ashx?json=1&type=Model&genreTypeId=1")?;
			//url borrow scope
			{
				let mut query=url.query_pairs_mut();//borrow here
				query.append_pair("assetid",asset_id.to_string().as_str());
				match group{
					Some(group_id)=>{query.append_pair("groupId",group_id.to_string().as_str());},
					None=>(),
				}
			}
			
			let body=tokio::fs::read_to_string(file).await?;
			let mut resp=client.post(url.clone())
			.header("Cookie",cookie)
			.body(body.clone())
			.send().await?;

			//This is called a CSRF challenge apparently
			if resp.status()==reqwest::StatusCode::FORBIDDEN{
				if let Some(csrf_token)=resp.headers().get("X-CSRF-Token"){
					resp=client.post(url)
					.header("X-CSRF-Token",csrf_token)
					.header("Cookie",cookie)
					.body(body)
					.send().await?;
				}else{
					return Err(anyhow::Error::msg("Roblox returned 403 with no CSRF"));
				}
			}

			Ok((asset_id,resp.bytes().await?))
		}
	})
	.buffer_unordered(CONCURRENT_REQUESTS)
	.for_each(|b:AResult<_>|async{
			match b{
				Ok((asset_id,body))=>{
					println!("asset_id={} response.body={:?}",asset_id,body);
				},
				Err(e)=>eprintln!("ul error: {}",e),
			}
		}).await;
	Ok(())
}

fn read_readable(mut readable:impl Read)->AResult<Vec<u8>>{
	let mut contents=Vec::new();
	readable.read_to_end(&mut contents)?;
	Ok(contents)
}

async fn download_list(cookie:String,asset_id_file_map:AssetIDFileMap)->AResult<()>{
	let client=reqwest::Client::new();
	futures::stream::iter(asset_id_file_map)
	.map(|(asset_id,file)|{
		let client=&client;
		let cookie=cookie.as_str();
		async move{
			let resp=client.get(format!("https://assetdelivery.roblox.com/v1/asset/?ID={}",asset_id))
			.header("Cookie",cookie)
			.send().await?;
			Ok((file,resp.bytes().await?))
		}
	})
	.buffer_unordered(CONCURRENT_REQUESTS)
	.for_each(|b:AResult<_>|async{
			match b{
				Ok((dest,body))=>{
					let contents=match maybe_gzip_decode(&mut std::io::Cursor::new(body)){
						Ok(ReaderType::GZip(readable))=>read_readable(readable),
						Ok(ReaderType::Raw(readable))=>read_readable(readable),
						Err(e)=>Err(e),
					};
					match contents{
						Ok(data)=>match tokio::fs::write(dest,data).await{
							Err(e)=>eprintln!("fs error: {}",e),
							_=>(),
						},
						Err(e)=>eprintln!("gzip error: {}",e),
					};
				},
				Err(e)=>eprintln!("dl error: {}",e),
			}
		}).await;
	Ok(())
}

fn load_dom<R:Read+Seek>(input:&mut R)->AResult<rbx_dom_weak::WeakDom>{
	let mut first_8=[0u8;8];
	if let (Ok(()),Ok(()))=(std::io::Read::read_exact(input, &mut first_8),std::io::Seek::rewind(input)){
		match &first_8[0..4]{
			b"<rob"=>{
				match &first_8[4..8]{
					b"lox!"=>return rbx_binary::from_reader(input).map_err(anyhow::Error::msg),
					b"lox "=>return rbx_xml::from_reader(input,rbx_xml::DecodeOptions::default()).map_err(anyhow::Error::msg),
					other=>Err(anyhow::Error::msg(format!("Unknown Roblox file type {:?}",other))),
				}
			},
			_=>Err(anyhow::Error::msg("unsupported file type")),
		}
	}else{
		Err(anyhow::Error::msg("peek failed"))
	}
}

#[derive(PartialEq)]
enum Class{
	Folder,
	ModuleScript,
	LocalScript,
	Script,
	Model,
}

struct TreeNode{
	name:String,
	referent:Ref,
	parent:Ref,
	class:Class,
	children:Vec<Ref>,
}
impl TreeNode{
	fn new(name:String,referent:Ref,parent:Ref,class:Class)->Self{
		Self{
			name,
			referent,
			parent,
			class,
			children:Vec::new(),
		}
	}
}

enum TrimStackInstruction{
	Referent(Ref),
	IncrementScript,
	DecrementScript,
}

enum WriteStackInstruction<'a>{
	Node(&'a TreeNode),
	PushFolder(String),
	PopFolder,
	Destroy(Ref),
}

#[derive(Default,serde::Deserialize,serde::Serialize)]
struct PropertiesOverride{
	//Name:Option<String>,
	ClassName:Option<String>,
}
impl PropertiesOverride{
	fn is_some(&self)->bool{
		self.ClassName.is_some()
	}
}

fn sanitize<'a>(s:&'a str)->std::borrow::Cow<'a,str>{
	lazy_regex::regex!(r"[^a-zA-Z0-9._-]").replace_all(s,"_")
}

fn write_item(dom:&rbx_dom_weak::WeakDom,mut file:std::path::PathBuf,node:&TreeNode)->AResult<()>{
	file.push(sanitize(node.name.as_str()).as_ref());
	match node.class{
		Class::Folder=>(),
		Class::ModuleScript|Class::LocalScript|Class::Script=>{
			assert!(file.set_extension("lua"),"could not set extension");
			assert!(dom.get_by_ref(node.referent).is_some_and(|item|{
				//TODO: delete disabled scripts
				if let Some(rbx_dom_weak::types::Variant::String(source))=item.properties.get("Source"){
					std::fs::write(file,source).is_ok()
				}else{false}
			}),"some ting wong");
		},
		Class::Model=>{
			assert!(file.set_extension("rbxmx"));
			let output=std::io::BufWriter::new(std::fs::File::create(file)?);
			rbx_xml::to_writer_default(output,dom,&[node.referent])?;
		},
	}
	Ok(())
}

fn decompile(input_file:std::path::PathBuf,output_folder:std::path::PathBuf)->AResult<()>{
	//rules:
	//Class Script|LocalScript|ModuleScript->$Name.lua
	//Class Model->$Name.rbxmx
	//overrides.json per-folder [Override{name,class}]
	//Everything else goes into template.rbxlx

	//read file
	let mut input=std::io::BufReader::new(std::fs::File::open(input_file)?);
	let mut dom=load_dom(&mut input)?;

	let mut tree_refs=std::collections::HashMap::new();
	tree_refs.insert(dom.root_ref(),TreeNode::new(
		"src".to_string(),
		dom.root_ref(),
		Ref::none(),
		Class::Folder
	));

	//run rules
	let mut stack=vec![dom.root()];
	while let Some(item)=stack.pop(){
		let class=match item.class.as_str(){
			"ModuleScript"=>Class::ModuleScript,
			"LocalScript"=>Class::LocalScript,
			"Script"=>Class::Script,
			"Model"=>Class::Model,
			_=>Class::Folder,
		};
		let skip=match class{
			Class::Model=>true,
			_=>false,
		};
		if let Some(parent_node)=tree_refs.get_mut(&item.parent()){
			let referent=item.referent();
			let node=TreeNode::new(item.name.clone(),referent,parent_node.referent,class);
			parent_node.children.push(referent);
			tree_refs.insert(referent,node);
		}
		if skip{
			continue;
		}
		for &referent in item.children(){
			if let Some(c)=dom.get_by_ref(referent){
				stack.push(c);
			}
		}
	}

	//trim empty folders
	let mut script_count=0;
	let mut stack:Vec<TrimStackInstruction>=tree_refs.get(&dom.root_ref()).unwrap().children
	.iter().map(|&c|TrimStackInstruction::Referent(c)).collect();
	while let Some(instruction)=stack.pop(){
		match instruction{
			TrimStackInstruction::IncrementScript=>script_count+=1,
			TrimStackInstruction::DecrementScript=>script_count-=1,
			TrimStackInstruction::Referent(referent)=>{
				let mut delete=None;
				if let Some(node)=tree_refs.get_mut(&referent){
					if node.class==Class::Folder&&script_count!=0{
						node.class=Class::Model
					}
					if node.class==Class::Folder&&node.children.len()==0{
						delete=Some(node.parent);
					}else{
						//how the hell do I do this better without recursion
						let is_script=match node.class{
							Class::ModuleScript|Class::LocalScript|Class::Script=>true,
							_=>false,
						};
						//stack is popped from back
						if is_script{
							stack.push(TrimStackInstruction::DecrementScript);
						}
						for &child_referent in &node.children{
							stack.push(TrimStackInstruction::Referent(child_referent));
						}
						if is_script{
							stack.push(TrimStackInstruction::IncrementScript);
						}
					}
				}
				//trim referent
				if let Some(parent_ref)=delete{
					let parent_node=tree_refs.get_mut(&parent_ref)
					.expect("parent_ref does not exist in tree_refs");
					parent_node.children.remove(
						parent_node.children.iter()
						.position(|&r|r==referent)
						.expect("parent.children does not contain referent")
					);
					tree_refs.remove(&referent);
				}
			},
		}
	}

	//generate folders, models, and scripts
	//delete models and scripts from dom
	{
	let mut folder=output_folder.clone();
	let mut stack=vec![WriteStackInstruction::Node(tree_refs.get(&dom.root_ref()).unwrap())];
	while let Some(instruction)=stack.pop(){
		match instruction{
			WriteStackInstruction::PushFolder(component)=>folder.push(component),
			WriteStackInstruction::PopFolder=>assert!(folder.pop(),"weirdness"),
			WriteStackInstruction::Destroy(referent)=>dom.destroy(referent),
			WriteStackInstruction::Node(node)=>{
				//properties.json to override class or other simple properties
				let mut properties=PropertiesOverride::default();
				let has_children=node.children.len()!=0;
				match node.class{
					Class::Folder=>(),
					Class::ModuleScript=>{
						//.lua files are ModuleScript by default
						if has_children{
							properties.ClassName=Some("ModuleScript".to_string())
						}
					},
					Class::LocalScript=>properties.ClassName=Some("LocalScript".to_string()),
					Class::Script=>properties.ClassName=Some("Script".to_string()),
					Class::Model=>(),
				}
				if has_children||properties.is_some(){
					//push temp subfolder
					let mut subfolder=folder.clone();
					subfolder.push(sanitize(node.name.as_str()).as_ref());
					//make folder
					std::fs::create_dir(subfolder.clone())?;
					//write properties
					if properties.is_some(){
						let mut file=subfolder.clone();
						file.push("properties");
						assert!(file.set_extension("json"),"could not set extension");
						std::fs::write(file,serde_json::to_string(&properties)?)?
					}
					//write item in subfolder
					write_item(&dom,subfolder,node)?;
				}else{
					//write item
					write_item(&dom,folder.clone(),node)?;
				}
				//queue item to be deleted from dom after child objects are handled (stack is popped from the back)
				match node.class{
					Class::Folder=>(),
					_=>stack.push(WriteStackInstruction::Destroy(node.referent)),
				}
				if has_children{
					stack.push(WriteStackInstruction::PopFolder);
					for referent in &node.children{
						if let Some(c)=tree_refs.get(referent){
							stack.push(WriteStackInstruction::Node(c));
						}
					}
					stack.push(WriteStackInstruction::PushFolder(sanitize(node.name.as_str()).to_string()));
				}
			},
		}
	}
	}
	//write what remains in template.rbxlx
	{
		let mut file=output_folder.clone();
		file.push("template");
		assert!(file.set_extension("rbxlx"));
		let output=std::io::BufWriter::new(std::fs::File::create(file)?);
		rbx_xml::to_writer_default(output,&dom,&[dom.root_ref()])?;
	}

	Ok(())
}

fn compile(_folder:std::path::PathBuf,_file:std::path::PathBuf)->AResult<()>{
	Ok(())
}