//! Local interoperability client. The parent connects stdio to a reference server.
const std = @import("std");
const c9 = @import("cloud9");
const libc = std.c;
const Session = struct {
    client: c9.Client,
    requests: usize = 0,
    bytes_read: usize = 0,
    bytes_written: usize = 0,
    read_calls: usize = 0,
    write_calls: usize = 0,

    fn ask(s: *Session, request: c9.Client.Request) !c9.Client.Result {
        const tag = try s.client.submit(request);
        s.requests += 1;
        while (s.client.output().len != 0) {
            const output = s.client.output();
            s.write_calls += 1;
            // Fragment requests across their header and body fields.
            const n = libc.write(1, output.ptr, @min(output.len, 3));
            if (n <= 0) return error.Write;
            s.bytes_written += @intCast(n);
            s.client.wrote(@intCast(n));
        }
        while (true) {
            if (s.client.take()) |done| {
                if (done.tag != tag) return error.Tag;
                if (done.result == .fail) {
                    std.debug.print("remote error: {s}\n", .{done.result.fail});
                    return error.Remote;
                }
                return done.result;
            }
            if (s.client.dead) return error.Protocol;
            var buffer: [7]u8 = undefined;
            s.read_calls += 1;
            const n = libc.read(0, &buffer, buffer.len);
            if (n <= 0) return error.Read;
            s.bytes_read += @intCast(n);
            if (s.client.push(buffer[0..@intCast(n)]) != n) return error.InputFull;
        }
    }
};

pub fn main(init: std.process.Init) !void {
    const args = try init.minimal.args.toSlice(init.arena.allocator());
    if (args.len != 3) return error.Arguments;
    const seed = try std.fmt.parseInt(u64, args[1], 10);
    const rounds = try std.fmt.parseInt(usize, args[2], 10);
    if (rounds == 0 or rounds > 10000) return error.Arguments;
    var random: std.Random.DefaultPrng = .init(seed);
    var input: [8192]u8 = undefined;
    var output: [8192]u8 = undefined;
    var session: Session = .{ .client = .init(.{ .in = &input, .out = &output }) };
    const version = (try session.ask(.{ .version = .{} })).version;
    if (version.msize > input.len or !std.mem.eql(u8, version.version, "9P2000")) return error.Version;
    _ = try session.ask(.{ .attach = .{ .fid = 0, .uname = "user" } });
    var expected: [4096]u8 = @splat(0);
    var length: usize = 0;
    for (0..rounds) |_| {
        const walk = (try session.ask(.{ .walk = .{ .fid = 0, .newfid = 1, .names = &.{"file"} } })).walk;
        if (walk.nwqid != 1 or walk.wqid[0].type & c9.qtdir != 0) return error.Walk;
        _ = try session.ask(.{ .open = .{ .fid = 1, .mode = c9.ordwr } });
        const offset = random.random().uintLessThan(usize, 2048);
        const count = random.random().uintLessThan(usize, 1024) + 1;
        var data: [1024]u8 = undefined;
        random.random().bytes(data[0..count]);
        const written = (try session.ask(.{ .write = .{ .fid = 1, .offset = offset, .data = data[0..count] } })).write;
        if (written != count) return error.WriteCount;
        @memcpy(expected[offset..][0..count], data[0..count]);
        length = @max(length, offset + count);
        const result = (try session.ask(.{ .read = .{ .fid = 1, .offset = 0, .count = expected.len } })).read;
        if (!std.mem.eql(u8, result, expected[0..length])) return error.Contents;
        const stat = (try session.ask(.{ .stat = .{ .fid = 1 } })).stat;
        if (stat.length != length or !std.mem.eql(u8, stat.name, "file")) return error.Stat;
        const eof = (try session.ask(.{ .read = .{ .fid = 1, .offset = length, .count = 1 } })).read;
        if (eof.len != 0) return error.Eof;
        _ = try session.ask(.{ .clunk = .{ .fid = 1 } });
    }
    _ = try session.ask(.{ .clunk = .{ .fid = 0 } });
    std.debug.print("{{\"requests\":{d},\"bytes_read\":{d},\"bytes_written\":{d},\"read_calls\":{d},\"write_calls\":{d},\"seed\":{d},\"rounds\":{d}}}\n", .{ session.requests, session.bytes_read, session.bytes_written, session.read_calls, session.write_calls, seed, rounds });
}