// Copyright (C) 2023-2099 The crate authors.
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU Affero General Public License as published by the
// Free Software Foundation, either version 3 of the License, or (at your
// option) any later version.
//
// This program 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 Affero General Public License
// for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

use std::ffi::OsString;
use std::fmt::Display;
use std::fs::File;
use std::io::{self, BufWriter, Read, Write};
use std::path::{Path, PathBuf};

use minidom::Error as MinidomError;
use quote::{format_ident, quote, TokenStreamExt};
use scansion::{read_actions_component, read_spec, Spec};

fn generate_spec_tokens(spec: Spec) -> Result<impl TokenStreamExt + Display, MinidomError> {
	println!("FOO0");

	let docstr = {
		let mut tmp = String::new();
		if let Some(ref meta) = spec.metadata {
			tmp.push_str(meta.title.as_str());
			tmp.push('\n');

			if let Some(ref desc) = meta.description {
				tmp.push_str(desc.as_str());
				tmp.push('\n');
			}

			for tag in &meta.tags {
				tmp.push_str("tag: ");
				tmp.push_str(tag.as_str());
				tmp.push('\n');
			}
		} else {
			tmp.push_str("No metadata");
		}

		tmp
	};

	let context = spec.context.clone();
	let actions = read_actions_component(spec, &context).unwrap();

	let stanzas_in = actions
		.inbound
		.into_iter()
		.map(|elem| {
			// TODO: Prevent having to parse elements again.
			// We do need some kind of structure already though to be able to verify the presence
			// of attrs and all before the generation.
			let elem_str = String::from(&elem);
			quote! { ScanElement::new(#elem_str.parse::<Element>().unwrap()).apply_context(&context) }
		})
		.collect::<Vec<_>>();

	let stanzas_out = actions
		.outbound
		.into_iter()
		.map(|elem| {
			let elem_str = String::from(&elem);
			quote! {
				component.expect(
					#elem_str.parse::<ScanElement>().unwrap().apply_context(&context)
				);
			}
		})
		.collect::<Vec<_>>();

	let (keys, values) =
		context
			.clone()
			.into_iter()
			.fold((vec![], vec![]), |(mut keys, mut values), (k, v)| {
				keys.push(quote! { #k });
				values.push(quote! { #v });
				(keys, values)
			});

	Ok(quote! {
		#![doc = #docstr]
		use crate::component::TestComponent;
		use crate::handlers::handle_stanza;
		use crate::room::Room;

		use ::std::collections::HashMap;
		use ::xmpp_parsers::{Jid, BareJid, FullJid, Element};
		use ::scansion::{ScanElement, Entity, Client};

		#[tokio::test]
		async fn spec() {
			let context: ::scansion::Context = {
				let mut tmp = ::std::collections::HashMap::new();
				let (keys, values) = (vec![#(#keys),*], vec![#(#values),*]);
				for (k, v) in keys.iter().zip(values.iter()) {
					tmp.insert(String::from(*k), v.clone());
				}
				tmp
			};

			let stanzas_in = vec![#(#stanzas_in),*];
			let mut component = TestComponent::new_scan(stanzas_in);
			let mut rooms: HashMap<BareJid, Room> = HashMap::new();

			#(#stanzas_out)*

			println!("FOO: {component:?}");
			handle_stanza(&mut component, &mut rooms).await.unwrap();
		}
	})
}

fn generate_mod_tokens(modfiles: Vec<OsString>) -> impl TokenStreamExt + Display {
	let modfiles: Vec<_> = modfiles
		.into_iter()
		.map(|s| format_ident!("{}", s.into_string().unwrap().strip_suffix(".rs").unwrap()))
		.collect();
	quote! {
		/// Scansion tests module.
		/// These tests are generated by the build script, DO NOT EDIT.

		#(#[cfg(test)] mod #modfiles;)*
	}
}

fn read_input_dir(indir: PathBuf, outdir: PathBuf) -> io::Result<Vec<OsString>> {
	// Will be used to generate mod.rs
	let mut modfiles: Vec<OsString> = Vec::new();

	for entry in indir.read_dir()? {
		let mut p = entry?.path();
		match p.extension() {
			Some(ext) if ext == "scs" => (),
			_ => continue,
		}

		let mut infile = File::open(p.clone())?;
		let mut contents = String::new();
		infile.read_to_string(&mut contents)?;

		let spec = read_spec(&contents);
		match spec {
			Ok(_) => println!("Path: {p:?}: \x1b[32m OK\x1b[0m"),
			Err(err) => {
				println!("Path: {p:?}: \x1b[31mERR\x1b[0m\n{err:?}");
				continue;
			}
		}

		// Path is now only going to be used as .rs
		p.set_extension("rs");

		let filename = OsString::from(p.file_name().unwrap());
		let outpath = outdir.join(filename.clone());
		println!("Outpath: {outpath:?}");

		let tokens = generate_spec_tokens(spec.unwrap()).unwrap();
		let mut output = BufWriter::new(File::create(&outpath)?);
		write!(output, "{}", tokens)?;

		// Add to the set of files for which generation succeeded to then generate mod.rs
		modfiles.push(filename);
	}

	Ok(modfiles)
}

fn main() -> io::Result<()> {
	let indir = Path::new("./specs");
	let outdir = Path::new("./src/tests/scansion");

	if !indir.is_dir() || !outdir.is_dir() {
		return Err(io::Error::new(
			io::ErrorKind::Other,
			"Input and output paths must be directories.",
		));
	}

	let modfiles = read_input_dir(indir.to_path_buf(), outdir.to_path_buf())?;

	let mut modout = BufWriter::new(File::create(outdir.join("mod.rs"))?);
	let tokens = generate_mod_tokens(modfiles);
	write!(modout, "{}", tokens)?;

	Ok(())
}