use std::iter::IntoIterator;
use std::sync::Arc;
use axum::Extension;
use axum::extract::Path;
use axum::http::{HeaderMap, Response, StatusCode};
use axum_extra::extract::Query;
use mediatype::{MediaTypeBuf, MediaTypeList};
use serde::Deserialize;
use acrate_database::diesel::GroupedBy;
use acrate_database::diesel_async::{AsyncConnection, AsyncPgConnection};
use acrate_database::meta::{MetaAlias, MetaLink, MetaLinkProperty, MetaLinkTitle, MetaProperty, MetaSubject};
use acrate_rd::jrd::ResourceDescriptorLinkJRD;
use acrate_rd::xrd::{ResourceDescriptorLinkXRD, ResourceDescriptorPropertyXRD, ResourceDescriptorTitleXRD};
use crate::config;

#[derive(Debug, Clone, Deserialize)]
pub struct WebfingerQuery {
	pub resource: Option<String>,
	
	#[serde(default)]
	pub rel: Vec<String>,
}

pub async fn webfinger_handler(
	Path(path): Path<String>,
	Query(WebfingerQuery {resource, rel}): Query<WebfingerQuery>,
	headers: HeaderMap,
	Extension(mj): Extension<Arc<minijinja::Environment<'static>>>,
) -> Result<Response<String>, StatusCode> {
	log::info!("Handling a WebFinger request!");
	
	let resource = resource.unwrap_or_else(|| "".to_string());
	log::debug!("Resource is: {resource:#?}");
	
	let path = format!("/{path}");
	log::debug!("Path is: {path:#?}");
	
	log::debug!("Rel is: {rel:#?}");
	
	let accept = headers.get("Accept");
	log::debug!("Accept is: {accept:#?}");
	let accept = accept
		.map(|h| h.to_str())
		.unwrap_or(Ok("*/*"))
		.map(|h| MediaTypeList::new(h))
		.map_err(|_| StatusCode::BAD_REQUEST)?;
	
	let mut response = Response::new("".to_string());
	
	let mut conn = AsyncPgConnection::establish(config::ACRATE_WEBFINGER_DATABASE_URL())
		.await
		.map_err(|_| StatusCode::BAD_GATEWAY)?;
	
	let subjects = MetaSubject::aquery_matching(&mut conn, &path, &resource)
		.await
		.map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

	let subject = subjects.first()
		.ok_or(StatusCode::NOT_FOUND)?;

	if subject.redirect.is_some() {
		{
			let headers = response.headers_mut();
			headers.insert(
				"Location",
				subject.redirect
					.as_ref()
					.expect("redirect not to have become suddenly None")
					.parse()
					.map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?
			);
		}
		{
			let status = response.status_mut();
			*status = StatusCode::FOUND;
		}

		return Ok(response);
	}

	let subject = subject.subject.clone();

	let aliases = MetaAlias::aquery_matching(&mut conn, &path, &resource)
		.await
		.map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
	
	let properties = MetaProperty::aquery_matching(&mut conn, &path, &resource)
		.await
		.map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
	
	let links = MetaLink::aquery_matching(&mut conn, &path, &resource)
		.await
		.map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
	
	let link_properties = MetaLinkProperty::aquery_by_link(&mut conn, &links)
		.await
		.map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?
		.grouped_by(&links);
	
	let link_titles = MetaLinkTitle::aquery_by_link(&mut conn, &links)
		.await
		.map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?
		.grouped_by(&links);
	
	let links_full: Vec<(MetaLink, Vec<MetaLinkProperty>, Vec<MetaLinkTitle>)> = links
		.into_iter()
		.zip(link_properties)
		.zip(link_titles)
		.map(|((link, properties), titles)| (link, properties, titles))
		.collect();
	
	{
		let headers = response.headers_mut();
		headers.insert(
			"Access-Control-Allow-Origin",
			"*".parse().unwrap()
		);
	}
	
	for media_type in accept.into_iter() {
		let media_type = match media_type {
			Err(e) => {
				log::debug!("Skipping error while parsing media type: {e:?}");
				continue;
			},
			Ok(media_type) => media_type
		};
		
		{
			let headers = response.headers_mut();
			headers.insert(
				"Content-Type",
				media_type.to_string()
					.parse()
					.map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?
			);
		}

		match media_type.essence().to_string().to_ascii_lowercase().as_str() {
			"*/*" | "application/json" | "application/jrd+json" => {
				let aliases = aliases
					.into_iter()
					.map(|alias| alias.alias)
					.collect();
				
				let properties = properties
					.into_iter()
					.map(|prop| (prop.rel, prop.value))
					.collect();
				
				let links = links_full
					.into_iter()
					.map(|(link, properties, titles)| ResourceDescriptorLinkJRD {
						rel: link.rel,
						r#type: link.type_.map(|m| m.0),
						href: link.href,
						template: link.template,
						properties: properties
							.into_iter()
							.map(|property| (property.rel, property.value))
							.collect(),
						titles: titles
							.into_iter()
							.map(|title| (title.language, title.value))
							.collect(),
					})
					.collect::<Vec<ResourceDescriptorLinkJRD>>();
				
				let rd = acrate_rd::jrd::ResourceDescriptorJRD {
					subject,
					aliases,
					properties,
					links,
				};
				
				let json = serde_json::to_string_pretty(&rd)
					.map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
				
				{
					let body = response.body_mut();
					body.push_str(&json);
				}
				
				return Ok(response);
			},
			"application/xml" | "application/xrd+xml" => {
				let aliases = aliases
					.into_iter()
					.map(|alias| alias.alias)
					.collect();
				
				let properties: Vec<ResourceDescriptorPropertyXRD> = properties
					.into_iter()
					.map(|prop| ResourceDescriptorPropertyXRD {
						rel: prop.rel,
						value: prop.value,
					})
					.collect();
				
				let links = links_full
					.into_iter()
					.map(|(link, properties, titles)| ResourceDescriptorLinkXRD {
						rel: link.rel,
						r#type: link.type_.map(|m| m.0),
						href: link.href,
						template: link.template,
						properties: properties
							.into_iter()
							.map(|property| ResourceDescriptorPropertyXRD {
								rel: property.rel,
								value: property.value,
							})
							.collect(),
						titles: titles
							.into_iter()
							.map(|title| ResourceDescriptorTitleXRD {
								language: title.language,
								value: title.value,
							})
							.collect(),
					})
					.collect::<Vec<ResourceDescriptorLinkXRD>>();
				
				let rd = acrate_rd::xrd::ResourceDescriptorXRD {
					subject,
					aliases,
					properties,
					links,
				};
				
				let xml = quick_xml::se::to_string(&rd)
					.map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
				
				{
					let body = response.body_mut();
					body.push_str(r#"<?xml version="1.0" encoding="UTF-8"?>"#);
					body.push_str(&xml);
				}
				
				return Ok(response);
			},
			"text/html" => {
				let aliases: Vec<String> = aliases.into_iter()
					.map(|alias| alias.alias)
					.collect();

				let properties: Vec<(String, Option<String>)> = properties.into_iter()
					.map(|prop| {
						(prop.rel, prop.value)
					})
					.collect();

				let links: Vec<(String, Option<MediaTypeBuf>, Option<String>, Option<String>, Vec<(String, Option<String>)>, Vec<(String, String)>)> = links_full
					.into_iter()
					.map(|(link, properties, titles)| {
						(
							link.rel,
							link.type_.map(|m| m.0),
							link.href,
							link.template,
							properties.into_iter()
								.map(|prop| (prop.rel, prop.value))
								.collect::<Vec<(String, Option<String>)>>(),
							titles.into_iter()
								.map(|title| (title.language, title.value))
								.collect::<Vec<(String, String)>>()
						)
					})
					.collect();

				let html = mj.get_template("rd.html.j2")
					.expect("rd.html.j2 to exist")
					.render(
						minijinja::context!(
							path => path,
							subject => subject,
							aliases => aliases,
							properties => properties,
							links => links,
						)
					)
					.map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

				{
					let body = response.body_mut();
					body.push_str(&html);
				}
				
				return Ok(response);
			},
			_ => {
				continue;
			},
		}
	}
	
	Err(StatusCode::NOT_ACCEPTABLE)
}