// Copyright 2019-2021 Parity Technologies (UK) Ltd.
//
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//! Contains common builders for hyper responses.

use crate::types::v2::{
	error::{ErrorCode, RpcError},
	params::{Id, TwoPointZero},
};

const JSON: &str = "application/json; charset=utf-8";
const TEXT: &str = "text/plain";

/// Create a response for json internal error.
pub fn internal_error() -> hyper::Response<hyper::Body> {
	let error = serde_json::to_string(&RpcError {
		jsonrpc: TwoPointZero,
		error: ErrorCode::InternalError.into(),
		id: Id::Null,
	})
	.expect("built from known-good data; qed");

	from_template(hyper::StatusCode::INTERNAL_SERVER_ERROR, error, JSON)
}

/// Create a text/plain response for not allowed hosts.
pub fn host_not_allowed() -> hyper::Response<hyper::Body> {
	from_template(hyper::StatusCode::FORBIDDEN, "Provided Host header is not whitelisted.\n".to_owned(), TEXT)
}

/// Create a text/plain response for disallowed method used.
pub fn method_not_allowed() -> hyper::Response<hyper::Body> {
	from_template(
		hyper::StatusCode::METHOD_NOT_ALLOWED,
		"Used HTTP Method is not allowed. POST or OPTIONS is required\n".to_owned(),
		TEXT,
	)
}

/// Create a text/plain response for invalid CORS "Origin" headers.
pub fn invalid_allow_origin() -> hyper::Response<hyper::Body> {
	from_template(
        hyper::StatusCode::FORBIDDEN,
        "Origin of the request is not whitelisted. CORS headers would not be sent and any side-effects were cancelled as well.\n".to_owned(),
		TEXT,
    )
}

/// Create a text/plain response for invalid CORS "Allow-*" headers.
pub fn invalid_allow_headers() -> hyper::Response<hyper::Body> {
	from_template(
        hyper::StatusCode::FORBIDDEN,
        "Requested headers are not allowed for CORS. CORS headers would not be sent and any side-effects were cancelled as well.\n".to_owned(),
		TEXT,
    )
}

/// Create a json response for oversized requests (413)
pub fn too_large() -> hyper::Response<hyper::Body> {
	let error = serde_json::to_string(&RpcError {
		jsonrpc: TwoPointZero,
		error: ErrorCode::OversizedRequest.into(),
		id: Id::Null,
	})
	.expect("built from known-good data; qed");

	from_template(hyper::StatusCode::PAYLOAD_TOO_LARGE, error, JSON)
}

/// Create a json response for empty or malformed requests (400)
pub fn malformed() -> hyper::Response<hyper::Body> {
	let error =
		serde_json::to_string(&RpcError { jsonrpc: TwoPointZero, error: ErrorCode::ParseError.into(), id: Id::Null })
			.expect("built from known-good data; qed");

	from_template(hyper::StatusCode::BAD_REQUEST, error, JSON)
}

/// Create a response body.
fn from_template<S: Into<hyper::Body>>(
	status: hyper::StatusCode,
	body: S,
	content_type: &'static str,
) -> hyper::Response<hyper::Body> {
	hyper::Response::builder()
		.status(status)
		.header("content-type", hyper::header::HeaderValue::from_static(content_type))
		.body(body.into())
		// Parsing `StatusCode` and `HeaderValue` is infalliable but
		// parsing body content is not.
		.expect("Unable to parse response body for type conversion")
}

/// Create a valid JSON response.
pub fn ok_response(body: String) -> hyper::Response<hyper::Body> {
	from_template(hyper::StatusCode::OK, body, JSON)
}