#include <green_crdt/v0/text_document.hpp>
#include <nlohmann/json.hpp>

extern "C" {
#include <zed_net.h>
}

#include <memory>
#include <string_view>
#include <variant>

#include <iostream>
#include <cassert>

// single letter agent, for testing only
//using Agent = char;
using Agent = uint16_t; // tmp local port
using Doc = GreenCRDT::V0::TextDocument<Agent>;
using ListType = Doc::ListType;

std::ostream& operator<<(std::ostream& out, const std::optional<ListType::ListID>& id) {
	if (id.has_value()) {
		out << id.value().id << "-" << id.value().seq;
	} else {
		out << "null";
	}
	return out;
}

std::ostream& operator<<(std::ostream& out, const ListType::OpAdd& op) {
	out
		<< "Add{ id:" << op.id.id
		<< "-" << op.id.seq
		<< ", v:" << op.value
		<< ", l:" << op.parent_left
		<< ", r:" << op.parent_right
		<< " }"
	;
	return out;
}

std::ostream& operator<<(std::ostream& out, const ListType::OpDel& op) {
	out
		<< "Del{ id:" << op.id.id
		<< "-" << op.id.seq
		<< " }"
	;
	return out;
}

std::ostream& operator<<(std::ostream& out, const Doc::Op& op) {
	if (std::holds_alternative<ListType::OpAdd>(op)) {
		out << std::get<ListType::OpAdd>(op);
	} else if (std::holds_alternative<ListType::OpDel>(op)) {
		out << std::get<ListType::OpDel>(op);
	}
	return out;
}

std::ostream& operator<<(std::ostream& out, const std::optional<char>& id) {
	if (id.has_value()) {
		out << id.value();
	} else {
		out << "null";
	}
	return out;
}

std::ostream& operator<<(std::ostream& out, const ListType::Entry& e) {
	out
		<< "{ id:" << e.id.id
		<< "-" << e.id.seq
		<< ", v:" << e.value
		<< ", l:" << e.parent_left
		<< ", r:" << e.parent_right
		<< " }"
	;
	return out;
}

static bool send_response(zed_net_socket_t* remote_socket, const int64_t id, const nlohmann::json& j) {
	auto j_msg = nlohmann::json::array();

	j_msg.push_back(id);
	j_msg.push_back(j);

	std::string str = j_msg.dump();
	str += '\n';

	auto ret = zed_net_tcp_socket_send(remote_socket, str.data(), str.size());
	return ret == 0;
}

static bool send_command(zed_net_socket_t* remote_socket, const std::string_view mode, const std::string_view command) {
	auto j = nlohmann::json::array();

	j.push_back(mode);
	j.push_back(command);

	std::string str = j.dump();
	str += '\n';

	auto ret = zed_net_tcp_socket_send(remote_socket, str.data(), str.size());
	return ret == 0;
}

static bool send_setup(zed_net_socket_t* remote_socket) {
	return send_command(remote_socket, "ex",

// vars
R"(
let b:green_crdt_timer_can_send = v:true
let b:green_crdt_timer_can_fetch = v:true
let b:green_crdt_dirty = v:true
)"

// send
R"(
function! GreenCRDTSendTimerCallback(timer) abort
	let b:green_crdt_timer_can_send = v:true
	call GreenCRDTCheckTimeAndSend()
endfunction
)"

// TODO: make send sync? (ch_evalexpr())
R"(
function! GreenCRDTCheckTimeAndSend() abort
	if b:green_crdt_timer_can_send && b:green_crdt_dirty
		let b:green_crdt_timer_can_send = v:false
		call ch_sendexpr(b:channel, [{'cmd': 'full_buffer', 'lines': getbufline(bufnr(), 1, '$')}])
		let b:green_crdt_dirty = v:false
		call timer_start(100, 'GreenCRDTSendTimerCallback')
	endif
endfunction
)"

// fetch
R"(
function! GreenCRDTFetchTimerCallback(timer) abort
	let b:green_crdt_timer_can_fetch = v:true
	call GreenCRDTCheckTimeAndFetch()
endfunction
)"

R"(
function! GreenCRDTCheckTimeAndFetch()
	if reg_executing() isnot# '' | return | endif

	if b:green_crdt_timer_can_fetch
		let b:green_crdt_timer_can_fetch = v:false

		" dont update when inserting or visual (or atleast not in visual)
		if mode() is# 'n'
			let l:response = ch_evalexpr(b:channel, [{'cmd': 'fetch_changes'}])
			for [line_number, line] in l:response
				call setline(line_number, line)
			endfor

		endif

		let b:green_crdt_fetch_timer = timer_start(503, 'GreenCRDTFetchTimerCallback')
	endif
endfunction
)"

// change event
R"(
function! GreenCRDTChangeEvent()
	let b:green_crdt_dirty = v:true
	call GreenCRDTCheckTimeAndSend()
	call GreenCRDTCheckTimeAndFetch()
endfunction
)"

// TODO: pull changes

// cleanup, to be called by user
// delfunction fails for stop... but well
R"(
function! GreenCRDTStop()
	augroup green_crdt
		au!
	augroup END

	call timer_stop(b:green_crdt_fetch_timer)

	call ch_close(b:channel)

	delfunction GreenCRDTCheckTimeAndSend
	delfunction GreenCRDTCheckTimeAndFetch
	delfunction GreenCRDTSendTimerCallback
	delfunction GreenCRDTFetchTimerCallback
	delfunction GreenCRDTChangeEvent
	"delfunction GreenCRDTStop
	let b:green_crdt_timer_can_send = v:true
endfunction
)"

// this is a hack, bc for some EX mode IPC buggyness reason, it only works as single commands OR inside a function
R"(
function! GreenCRDTSetupEvents() abort
	augroup green_crdt
		au!
		au TextChanged <buffer> call GreenCRDTChangeEvent()
		au TextChangedI <buffer> call GreenCRDTChangeEvent()
	augroup END
endfunction
call GreenCRDTSetupEvents()
delfunction GreenCRDTSetupEvents
)"

R"(
let b:green_crdt_fetch_timer = timer_start(900, 'GreenCRDTFetchTimerCallback')

echo 'setup done'
)");
}

int main(void) {
	std::cout << "starting vim ipc server\n";

	if (zed_net_init() != 0) {
		std::cerr << "zed_net_init failed: " << zed_net_get_error() << "\n";
		return -1;
	}

	std::cout << "initialized zed_net\n";

	const uint16_t port {1337};
	zed_net_socket_t listen_socket;
	if (zed_net_tcp_socket_open(
		&listen_socket,
		port, // port
		0, // non blocking
		1 // listen
	) != 0) {
		std::cerr << "zed_net_tcp_socket_open failed: " << zed_net_get_error() << "\n";
		zed_net_shutdown();
		return -1;
	}

	std::cout << "listening on " << port << "\n";

	std::cout << "paste these commands into your vim for the current buffer:\n";
	std::cout << "  :let b:channel = ch_open('localhost:" << port << "')\n";

	std::cout << "paste this command to disconnect:\n  :call GreenCRDTStop()\n";

	zed_net_socket_t remote_socket;
	zed_net_address_t remote_address;
	if (zed_net_tcp_accept(&listen_socket, &remote_socket, &remote_address) != 0) {
		std::cerr << "zed_net_tcp_accept failed: " << zed_net_get_error() << "\n";
		zed_net_socket_close(&listen_socket);
		zed_net_shutdown();
		return -1;
	}

	std::cout << "got connection from " << zed_net_host_to_str(remote_address.host) << ":" << remote_address.port << "\n";

	std::cout << "sending setup\n";
	send_setup(&remote_socket);
	// send doauto text changed for inital buffer

	Doc doc;
	doc.local_agent = remote_address.port; // tmp: use local port as id

	while (true) {
		// 100MiB
		auto buffer = std::make_unique<std::array<uint8_t, 1024*1024*100>>();

		int64_t bytes_received {0};
		bytes_received = zed_net_tcp_socket_receive(&remote_socket, buffer->data(), buffer->size());
		if (bytes_received < 0) {
			std::cerr << "zed_net_tcp_socket_receive failed: " << zed_net_get_error() << "\n";
			zed_net_socket_close(&remote_socket);
			zed_net_socket_close(&listen_socket);
			zed_net_shutdown();
			return -1;
		} else if (bytes_received == 0) {
			std::cout << "got 0 bytes?\n";
			break; // connection closed
		}

		std::cout << "got " << bytes_received << " bytes\n";

		// expect json array(s separated by newlines)
		// TODO: new lines
		auto view = std::string_view{reinterpret_cast<const char*>(buffer->data()), static_cast<size_t>(bytes_received)};
		std::cout << "  raw: " << view;

		auto j = nlohmann::json::parse(view, nullptr, false);
		if (j.is_discarded()) {
			std::cerr << "invalid json\n";
			//break;
			continue; // whatever
		}

		//std::cout << "  j: " << j.dump() << "\n";

		if (!j.is_array()) {
			std::cerr << "json not array!\n";
			break;
		}

		int64_t command_seq = j.at(0);
		auto j_command_data = j.at(1);

		if (!j_command_data.is_array()) {
			std::cerr << "j_command_data not array!\n";
			break;
		}

		for (const auto& j_command : j_command_data) {
			if (!j_command.is_object()) {
				std::cerr << "j_command not obj!\n";
				break;
			}

			if (!j_command.count("cmd")) {
				std::cerr << "j_command does not have a 'cmd' field!\n";
				break;
			}

			if (!j_command.at("cmd").is_string()) {
				std::cerr << "command not a string!\n";
				break;
			}

			std::string command = j_command.at("cmd");

			if (command.empty()) {
				std::cerr << "command string empty!\n";
				break;
			} else if (command == "setup") { // setup callbacks etc, basically the plugin
				std::cout << "sending setup\n";
				send_setup(&remote_socket);
			} else if (command == "fetch_changes") { // setup callbacks etc, basically the plugin
				// apply changes (some) and gen vim inserts
				std::cout << "got fetch changes\n";

				auto j_res_line_list = nlohmann::json::array();

				if (true) { // external changes
					const auto crdt_text = doc.getText();
					std::string_view text_view {crdt_text};
					for (int64_t i = 1; ; i++) {
						const auto nl_pos = text_view.find_first_of("\n");
						if (nl_pos == std::string_view::npos) {
							// no more lines
							j_res_line_list.push_back(nlohmann::json::array({i, text_view}));
							break;
						} else {
							const auto line = text_view.substr(0, nl_pos);
							j_res_line_list.push_back(nlohmann::json::array({i, line}));

							assert(text_view.size() >= nl_pos+1);
							text_view = text_view.substr(nl_pos+1);
						}
					}
				}

				send_response(&remote_socket, command_seq, j_res_line_list);
			} else if (command == "full_buffer") { // vim is sending the full buffer
				// array of lines

				if (!j_command.count("lines")) {
					std::cerr << "lines list empty!\n";
					continue;
				}

				const auto& j_lines = j_command.at("lines");
				if (!j_lines.is_array()) {
					std::cerr << "lines list not an array!\n";
					continue;
				}

				std::string new_text;
				for (size_t i = 0; i < j_lines.size(); i++) {
					if (!j_lines.at(i).empty()) {
						new_text += static_cast<std::string>(j_lines.at(i));
					}

					if (i+1 < j_lines.size()) {
						new_text += "\n";
					}
				}

				//std::cout << "new_text:\n" << new_text << "\n";
				//std::cout << "old_text:\n" << doc.getText() << "\n";
				std::cout << "doc state: ";
					for (const auto& e : doc.state.list) {
						std::cout << e << " ";
					}
					std::cout << "\n";

				const auto ops = doc.merge(new_text);
				if (!ops.empty()) {
					std::cout << "ops.size: " << ops.size() << "\n";
					std::cout << "ops: ";
					for (const auto& op : ops) {
						std::cout << op << " ";
					}
					std::cout << "\n";
				}
				assert(doc.getText() == new_text);
			} else {
				std::cout << "unknown command '" << command << "'\n";
			}
		}
	}

	std::cout << "shutting down\n";

	zed_net_socket_close(&remote_socket);
	zed_net_socket_close(&listen_socket);
	zed_net_shutdown();
	return 0;
}