fediglam/src/http/server.zig

const std = @import("std");
const util = @import("util");
const http = @import("./lib.zig");

const response = @import("./server/response.zig");
const request = @import("./request.zig");
const os = std.os;

pub const Response = struct {
    alloc: std.mem.Allocator,
    stream: Stream,
    should_close: bool = false,

    pub const ResponseStream = response.ResponseStream(Stream.Writer);
    pub fn open(self: *Response, status: http.Status, headers: *const http.Fields) !ResponseStream {
        if (headers.get("Connection")) |hdr| {
            if (std.ascii.indexOfIgnoreCase(hdr, "close")) |_| self.should_close = true;
        }

        return response.open(self.alloc, self.stream.writer(), headers, status);
    }

    pub fn upgrade(self: *Response, status: http.Status, headers: *const http.Fields) !Stream {
        try response.writeRequestHeader(self.stream.writer(), headers, status);
        return self.stream;
    }
};
pub const StreamKind = enum {
    tcp,
};

pub const Stream = struct {
    kind: StreamKind,

    socket: os.socket_t,

    pub fn close(self: Stream) void {
        os.closeSocket(self.socket);
    }

    pub const ReadError = os.RecvFromError;
    pub const WriteError = os.SendError;

    pub const Reader = std.io.Reader(Stream, ReadError, read);
    pub const Writer = std.io.Writer(Stream, WriteError, write);

    pub fn read(self: Stream, buffer: []u8) ReadError!usize {
        if (std.io.is_async) @compileError("TODO: async not supported");
        if (self.kind != .tcp) @panic("TODO");

        return os.recv(self.socket, buffer, 0);
    }

    pub fn write(self: Stream, buffer: []const u8) WriteError!usize {
        if (std.io.is_async) @compileError("TODO: Async not supported yet");
        if (self.kind != .tcp) @panic("TODO");

        return os.send(self.socket, buffer, os.MSG.NOSIGNAL);
    }

    pub fn reader(self: Stream) Reader {
        return .{ .context = self };
    }

    pub fn writer(self: Stream) Writer {
        return .{ .context = self };
    }
};

pub const Server = struct {
    tcp_server: std.net.StreamServer,

    pub fn init() Server {
        return Server{
            .tcp_server = std.net.StreamServer.init(.{ .reuse_address = true }),
        };
    }

    pub fn deinit(self: *Server) void {
        self.tcp_server.deinit();
    }

    pub fn listen(self: *Server, address: std.net.Address) !void {
        try self.tcp_server.listen(address);
    }

    pub const Connection = struct {
        stream: Stream,
        address: std.net.Address,
    };

    pub fn handleLoop(
        self: *Server,
        allocator: std.mem.Allocator,
        ctx: anytype,
        handler: anytype,
    ) void {
        while (true) {
            const conn = self.tcp_server.accept() catch |err| {
                if (err == error.SocketNotListening) return;

                std.log.err("Error occurred accepting connection: {}", .{err});
                continue;
            };

            serveConn(
                allocator,
                Connection{
                    .stream = Stream{ .kind = .tcp, .socket = conn.stream.handle },
                    .address = conn.address,
                },
                ctx,
                handler,
            );
        }
    }

    fn serveConn(
        allocator: std.mem.Allocator,
        conn: Connection,
        ctx: anytype,
        handler: anytype,
    ) void {
        while (true) {
            var req = request.parse(allocator, conn.stream.reader()) catch |err| {
                return handleError(conn.stream.writer(), err) catch {};
            };

            var res = Response{
                .alloc = allocator,
                .stream = conn.stream,
            };

            handler(ctx, &req, &res);

            if (req.headers.get("Connection")) |hdr| {
                if (std.ascii.indexOfIgnoreCase(hdr, "close")) |_| return;
            } else if (req.headers.get("Keep-Alive")) |_| {
                // TODO: Support this
                return;
            } else if (req.protocol == .http_1_0) return;
            if (res.should_close) return;
        }
    }
};

/// Writes an error response message and requests closure of the connection
fn handleError(writer: anytype, err: anyerror) !void {
    const status: http.Status = switch (err) {
        error.EndOfStream => return, // Do nothing, the client closed the connection
        error.BadRequest => .bad_request,
        error.UnsupportedMediaType => .unsupported_media_type,
        error.HttpVersionNotSupported => .http_version_not_supported,

        else => .internal_server_error,
    };

    try writer.print("HTTP/1.1 {} {?s}\r\nConnection: close\r\n\r\n", .{ @enumToInt(status), status.phrase() });
}