module docker

import net.unix
import io
import net.http
import strings
import json
import util

const (
	socket               = '/var/run/docker.sock'
	buf_len              = 10 * 1024
	http_separator       = [u8(`\r`), `\n`, `\r`, `\n`]
	http_chunk_separator = [u8(`\r`), `\n`]
	timestamp_attr       = 'timestamp'
	api_version          = 'v1.41'
)

[heap]
pub struct DockerConn {
mut:
	socket &unix.StreamConn
	reader &io.BufferedReader
	// Data for the request that's currently being constructed.
	method       http.Method
	url          string
	params       map[string]string
	content_type string
	// Before send: body of the request
	// After send: body of response
	body string
	// HTTP head of the response
	head http.Response
}

// new_conn creates a new connection to the Docker daemon.
pub fn new_conn() !&DockerConn {
	s := unix.connect_stream(docker.socket)!

	d := &DockerConn{
		socket: s
		reader: io.new_buffered_reader(reader: s)
	}

	return d
}

// close closes the underlying socket connection.
pub fn (mut d DockerConn) close() ! {
	d.socket.close()!
}

// read_response_head consumes the socket's contents until it encounters
// '\r\n\r\n', after which it parses the response as an HTTP response.
// Importantly, this function never consumes the reader past the HTTP
// separator, so the body can be read fully later on.
fn (mut d DockerConn) read_response_head() ! {
	mut res := []u8{}

	util.read_until_separator(mut d.reader, mut res, docker.http_separator)!

	d.head = http.parse_response(res.bytestr())!
}

// read_response_body consumes the rest of the HTTP response and stores it as
// the response body. This function should only be called after
// read_response_head. This function always reads the entire response into
// memory, even if it's chunked.
fn (mut d DockerConn) read_response_body() ! {
	if d.head.status() == .no_content {
		return
	}

	mut builder := strings.new_builder(docker.buf_len)

	if d.head.header.get(.transfer_encoding) or { '' } == 'chunked' {
		mut body_stream := d.get_chunked_response_reader()

		util.reader_to_writer(mut body_stream, mut builder)!
	} else {
		content_length := d.head.header.get(.content_length)!.int()

		if content_length == 0 {
			d.body = ''

			return
		}

		mut buf := []u8{len: docker.buf_len}
		mut c := 0

		for builder.len < content_length {
			c = d.reader.read(mut buf)!

			builder.write(buf[..c])!
		}
	}

	d.body = builder.str()
}

// read_response is a convenience function that always consumes the entire
// response and loads it into memory. It should only be used when we're certain
// that the result isn't too large, as even chunked responses will get fully
// loaded into memory.
fn (mut d DockerConn) read_response() ! {
	d.read_response_head()!
	d.check_error()!
	d.read_response_body()!
}

// read_json_response<T> is a convenience function that runs read_response
// before parsing its contents, which is assumed to be JSON, into a struct.
fn (mut d DockerConn) read_json_response[T]() !T {
	d.read_response()!

	data := json.decode(T, d.body)!

	//$for field in T.fields {
	//$if field.typ is time.Time {
	// data.$(field.name) = time.parse_rfc3339(data.$(field.name + '_str'))?
	//}
	//}

	return data
}

// get_chunked_response_reader returns a ChunkedResponseReader using the socket
// as reader. This function should only be called after check_error.
fn (mut d DockerConn) get_chunked_response_reader() &ChunkedResponseReader {
	r := new_chunked_response_reader(d.reader)

	return r
}

// get_stream_format_reader returns a StreamFormatReader using the socket as
// reader. This function should only be called after check_error.
fn (mut d DockerConn) get_stream_format_reader() &StreamFormatReader {
	r := new_chunked_response_reader(d.reader)
	r2 := new_stream_format_reader(r)

	return r2
}

struct DockerError {
pub:
	message string
}

// check_error should be called after read_response_head. If the status code of
// the response is an error, the body is consumed and the Docker HTTP error is
// returned as a V error. If the status isn't the error, this function is a
// no-op, and the body can be read.
fn (mut d DockerConn) check_error() ! {
	if d.head.status().is_error() {
		d.read_response_body()!
		d_err := json.decode(DockerError, d.body)!

		return error_with_code('${d.head.status()}: ${d_err.message}', d.head.status_code)
	}
}