//! Adapts `debug.Debug` into core `Provider`s. The core mounts providers at
//! top level only, so one `DebugProvider` registers six of them, all sharing
//! the same `Debug` and the same snapshot pool:
//!
//!   /threads/<tid>/{name,stat,stack,regs}   (lists only live tids)
//!   /addr/<hex>                 "fn\nfile:line:col\nmodule\n"
//!   /mem/maps, /mem/<hex>       /proc/self/maps; raw bytes at address+offset (writable)
//!   /hex/<hex>                  hexdump of 256 bytes at the address
//!   /breakpoints/<tid>/{stack,regs,ctl}   ctl accepts "continue" (lists only paused tids)
//!   /panic/{message,stack,ctl}            ctl accepts "continue"
//!
//! /addr, /mem, /hex and /panic carry a README; /threads and /breakpoints
//! list nothing but tids so that a shell glob over them sees only threads.
//!
//! Handles encode `(kind, tid-or-address)` in 56 bits (the core keeps the
//! low 56 bits of a handle for the qid path): kind in bits 48..55, value in
//! bits 0..47. Handles carry no reference count, so `clunk` is a no-op.
//!
//! The core hands providers a buffer-based `read`, not a writer, so every
//! text file is generated at `open` into one of `snapshot_slots` fixed slots
//! (keyed by handle, reference counted across fids) and served from there; a
//! read at offset 0 regenerates, like the core's own dynamic files. `/mem/<hex>`
//! is read and written directly at address+offset and never snapshotted, and
//! `/mem/maps` is read straight from /proc/self/maps at the requested offset
//! (a big process has more mappings than a snapshot slot holds).
const std = @import("std");
const cloud9 = @import("cloud9");
const core = @import("../core.zig");
const debug = @import("debug.zig");
const Writer = std.Io.Writer;
const Provider = core.Provider;
const Handle = Provider.Handle;
const Error = Provider.Error;
const NodeStat = core.NodeStat;

pub const snapshot_slots = 8;
pub const snapshot_bytes = 32 * 1024;
/// Bytes shown by /hex/<hex>.
pub const hex_bytes = 256;

pub const Tree = enum(u8) { threads, addr, mem, hex, breakpoints, panic };
pub const tree_names = [_][]const u8{ "threads", "addr", "mem", "hex", "breakpoints", "panic" };

const Kind = enum(u8) {
    root = 0,
    readme,
    thread_dir,
    thread_name,
    thread_stat,
    thread_stack,
    thread_regs,
    addr_file,
    maps,
    mem_file,
    hex_file,
    bp_dir,
    bp_stack,
    bp_regs,
    bp_ctl,
    panic_message,
    panic_stack,
    panic_ctl,

    fn isDir(k: Kind) bool {
        return k == .root or k == .thread_dir or k == .bp_dir;
    }

    /// Text files generated into a snapshot slot at open.
    fn isText(k: Kind) bool {
        return switch (k) {
            .readme, .thread_name, .thread_stat, .thread_stack, .thread_regs, .addr_file, .hex_file, .bp_stack, .bp_regs, .panic_message, .panic_stack => true,
            else => false,
        };
    }

    fn isCtl(k: Kind) bool {
        return k == .bp_ctl or k == .panic_ctl;
    }

    fn mode(k: Kind) u32 {
        if (k.isDir()) return cloud9.dmdir | 0o555;
        if (k.isCtl()) return 0o222;
        if (k == .mem_file) return 0o666;
        return 0o444;
    }

    fn fixedName(k: Kind) ?[]const u8 {
        return switch (k) {
            .readme => "README",
            .thread_name => "name",
            .thread_stat => "stat",
            .thread_stack, .bp_stack, .panic_stack => "stack",
            .thread_regs, .bp_regs => "regs",
            .maps => "maps",
            .bp_ctl, .panic_ctl => "ctl",
            .panic_message => "message",
            else => null,
        };
    }
};

const value_bits = 48;
const value_mask: u64 = (1 << value_bits) - 1;

fn mk(kind: Kind, value: u64) Handle {
    return (@as(u64, @intFromEnum(kind)) << value_bits) | (value & value_mask);
}

fn kindOf(h: Handle) Kind {
    return @enumFromInt(@as(u8, @truncate(h >> value_bits)));
}

fn valueOf(h: Handle) u64 {
    return h & value_mask;
}

const readme_threads =
    \\One directory per thread of this process, named by tid:
    \\  name   the thread's comm
    \\  stat   state and a few fields of /proc/self/task/<tid>/stat
    \\  stack  "#n 0x<addr> in <fn> (<file>:<line>:<col>)" per frame
    \\  regs   general registers captured while the thread was stopped
    \\
;
const readme_addr =
    \\Walk any hex address: /addr/<hex> reads as "fn\nfile:line:col\nmodule\n".
    \\
;
const readme_mem =
    \\maps        /proc/self/maps
    \\<hex>       raw process memory at that address (+ file offset); writable
    \\
;
const readme_hex =
    \\Walk any hex address: /hex/<hex> is a hexdump of the 256 bytes there.
    \\
;
const readme_breakpoints =
    \\One directory per thread stopped in @breakpoint(), named by tid:
    \\  stack, regs   as under /threads
    \\  ctl           write "continue" to resume the thread
    \\
;
const readme_panic =
    \\message   the first panic's message (empty before any panic)
    \\stack     frames of the panicking thread
    \\ctl       write "continue" to let the default panic handler run
    \\
;

fn readmeFor(tree: Tree) []const u8 {
    return switch (tree) {
        .threads => readme_threads,
        .addr => readme_addr,
        .mem => readme_mem,
        .hex => readme_hex,
        .breakpoints => readme_breakpoints,
        .panic => readme_panic,
    };
}

const Slot = struct {
    handle: Handle = 0,
    refs: u32 = 0,
    len: u32 = 0,
    buf: [snapshot_bytes]u8 = undefined,
};

pub const DebugProvider = struct {
    d: *debug.Debug,
    slots: [snapshot_slots]Slot = @splat(.{}),
    /// Backs `NodeStat.name` until the next call.
    name_buf: [32]u8 = undefined,

    pub fn init(dp: *DebugProvider, d: *debug.Debug) void {
        dp.* = .{ .d = d };
    }

    /// The provider for one tree, to pass to `Shared.addProvider`.
    pub fn provider(dp: *DebugProvider, comptime tree: Tree) Provider {
        return .{ .name = tree_names[@intFromEnum(tree)], .ctx = dp, .vtable = vtableFor(tree) };
    }

    /// Mounts all six trees; `shared` is a `Server(cfg).Shared`.
    pub fn mountAll(dp: *DebugProvider, shared: anytype) error{Full}!void {
        inline for (comptime std.meta.tags(Tree)) |tree| try shared.addProvider(dp.provider(tree));
    }

    fn self(ctx: *anyopaque) *DebugProvider {
        return @ptrCast(@alignCast(ctx));
    }

    fn vtableFor(comptime tree: Tree) *const Provider.VTable {
        return &struct {
            const vt: Provider.VTable = .{
                .walk = walkFn,
                .stat = statFn,
                .list = listFn,
                .open = openFn,
                .read = readFn,
                .write = writeFn,
                .close = closeFn,
                .clunk = clunkFn,
            };
            fn walkFn(ctx: *anyopaque, parent: Handle, name: []const u8) Error!Handle {
                return self(ctx).walk(tree, parent, name);
            }
            fn statFn(ctx: *anyopaque, h: Handle, out: *NodeStat) Error!void {
                return self(ctx).stat(tree, h, out);
            }
            fn listFn(ctx: *anyopaque, dir: Handle, index: usize, out: *NodeStat) Error!bool {
                return self(ctx).list(tree, dir, index, out);
            }
            fn openFn(ctx: *anyopaque, h: Handle, mode: u8) Error!void {
                return self(ctx).open(tree, h, mode);
            }
            fn readFn(ctx: *anyopaque, h: Handle, offset: u64, buf: []u8) Error!usize {
                return self(ctx).read(tree, h, offset, buf);
            }
            fn writeFn(ctx: *anyopaque, h: Handle, offset: u64, data: []const u8) Error!usize {
                return self(ctx).write(tree, h, offset, data);
            }
            fn closeFn(ctx: *anyopaque, h: Handle) void {
                self(ctx).close(h);
            }
            fn clunkFn(_: *anyopaque, _: Handle) void {}
        }.vt;
    }

    // -- naming ------------------------------------------------------------

    fn parseTid(name: []const u8) ?u32 {
        if (name.len == 0 or name.len > 10) return null;
        for (name) |ch| if (!std.ascii.isDigit(ch)) return null;
        return std.fmt.parseInt(u32, name, 10) catch null;
    }

    fn parseHex(name: []const u8) ?u64 {
        const digits = if (std.mem.startsWith(u8, name, "0x")) name[2..] else name;
        if (digits.len == 0 or digits.len > 12) return null;
        for (digits) |ch| if (!std.ascii.isHex(ch)) return null;
        const v = std.fmt.parseInt(u64, digits, 16) catch return null;
        if (v > value_mask) return null;
        return v;
    }

    fn nodeName(dp: *DebugProvider, h: Handle) []const u8 {
        const k = kindOf(h);
        if (k.fixedName()) |n| return n;
        return switch (k) {
            .root => "",
            .thread_dir, .bp_dir => std.fmt.bufPrint(&dp.name_buf, "{d}", .{valueOf(h)}) catch unreachable,
            .addr_file, .mem_file, .hex_file => std.fmt.bufPrint(&dp.name_buf, "{x}", .{valueOf(h)}) catch unreachable,
            else => unreachable,
        };
    }

    // -- vtable ------------------------------------------------------------

    fn walk(dp: *DebugProvider, tree: Tree, parent: Handle, name: []const u8) Error!Handle {
        const k = kindOf(parent);
        if (std.mem.eql(u8, name, ".")) return parent;
        if (!k.isDir()) return error.NotDir;
        if (std.mem.eql(u8, name, "..")) return Provider.root;
        switch (k) {
            .root => {
                if (tree != .threads and tree != .breakpoints and std.mem.eql(u8, name, "README")) return mk(.readme, 0);
                switch (tree) {
                    .threads => {
                        const tid = parseTid(name) orelse return error.NotFound;
                        if (!dp.d.threadExists(tid)) return error.NotFound;
                        return mk(.thread_dir, tid);
                    },
                    .addr => return mk(.addr_file, parseHex(name) orelse return error.NotFound),
                    .mem => {
                        if (std.mem.eql(u8, name, "maps")) return mk(.maps, 0);
                        return mk(.mem_file, parseHex(name) orelse return error.NotFound);
                    },
                    .hex => return mk(.hex_file, parseHex(name) orelse return error.NotFound),
                    .breakpoints => {
                        const tid = parseTid(name) orelse return error.NotFound;
                        if (!dp.d.isPaused(tid)) return error.NotFound;
                        return mk(.bp_dir, tid);
                    },
                    .panic => {
                        if (std.mem.eql(u8, name, "message")) return mk(.panic_message, 0);
                        if (std.mem.eql(u8, name, "stack")) return mk(.panic_stack, 0);
                        if (std.mem.eql(u8, name, "ctl")) return mk(.panic_ctl, 0);
                        return error.NotFound;
                    },
                }
            },
            .thread_dir => {
                const tid = valueOf(parent);
                if (std.mem.eql(u8, name, "name")) return mk(.thread_name, tid);
                if (std.mem.eql(u8, name, "stat")) return mk(.thread_stat, tid);
                if (std.mem.eql(u8, name, "stack")) return mk(.thread_stack, tid);
                if (std.mem.eql(u8, name, "regs")) return mk(.thread_regs, tid);
                return error.NotFound;
            },
            .bp_dir => {
                const tid = valueOf(parent);
                if (std.mem.eql(u8, name, "stack")) return mk(.bp_stack, tid);
                if (std.mem.eql(u8, name, "regs")) return mk(.bp_regs, tid);
                if (std.mem.eql(u8, name, "ctl")) return mk(.bp_ctl, tid);
                return error.NotFound;
            },
            else => unreachable,
        }
    }

    fn fill(dp: *DebugProvider, tree: Tree, h: Handle, out: *NodeStat) void {
        const k = kindOf(h);
        out.* = .{
            .mode = k.mode(),
            .length = if (k == .readme) readmeFor(tree).len else 0,
            .name = dp.nodeName(h),
            .handle = h,
        };
    }

    fn stat(dp: *DebugProvider, tree: Tree, h: Handle, out: *NodeStat) Error!void {
        dp.fill(tree, h, out);
    }

    fn list(dp: *DebugProvider, tree: Tree, dir: Handle, index: usize, out: *NodeStat) Error!bool {
        const k = kindOf(dir);
        if (!k.isDir()) return error.NotDir;
        const h: Handle = switch (k) {
            .root => switch (tree) {
                .threads => mk(.thread_dir, dp.d.threadAt(index) orelse return false),
                .addr, .hex => if (index == 0) mk(.readme, 0) else return false,
                .mem => switch (index) {
                    0 => mk(.readme, 0),
                    1 => mk(.maps, 0),
                    else => return false,
                },
                .breakpoints => mk(.bp_dir, dp.d.pausedAt(index) orelse return false),
                .panic => switch (index) {
                    0 => mk(.readme, 0),
                    1 => mk(.panic_message, 0),
                    2 => mk(.panic_stack, 0),
                    3 => mk(.panic_ctl, 0),
                    else => return false,
                },
            },
            .thread_dir => switch (index) {
                0 => mk(.thread_name, valueOf(dir)),
                1 => mk(.thread_stat, valueOf(dir)),
                2 => mk(.thread_stack, valueOf(dir)),
                3 => mk(.thread_regs, valueOf(dir)),
                else => return false,
            },
            .bp_dir => switch (index) {
                0 => mk(.bp_stack, valueOf(dir)),
                1 => mk(.bp_regs, valueOf(dir)),
                2 => mk(.bp_ctl, valueOf(dir)),
                else => return false,
            },
            else => unreachable,
        };
        dp.fill(tree, h, out);
        return true;
    }

    fn open(dp: *DebugProvider, tree: Tree, h: Handle, mode: u8) Error!void {
        const k = kindOf(h);
        const acc = mode & 3;
        const wants_write = acc == cloud9.owrite or acc == cloud9.ordwr;
        const wants_read = acc != cloud9.owrite;
        if (k.isDir()) {
            if (wants_write or mode & cloud9.otrunc != 0) return error.IsDir;
            return;
        }
        if (k.isCtl()) {
            if (wants_read) return error.Perm;
            return;
        }
        if (k == .mem_file) return;
        if (wants_write or mode & cloud9.otrunc != 0) return error.Perm;
        if (k == .maps) return;
        std.debug.assert(k.isText());
        const slot = dp.takeSlot(h) orelse return error.NoSpace;
        errdefer dp.releaseSlot(slot);
        try dp.generate(tree, h, slot);
    }

    fn close(dp: *DebugProvider, h: Handle) void {
        if (!kindOf(h).isText()) return;
        if (dp.findSlot(h)) |s| dp.releaseSlot(s);
    }

    fn read(dp: *DebugProvider, tree: Tree, h: Handle, offset: u64, buf: []u8) Error!usize {
        const k = kindOf(h);
        if (k.isDir()) return error.IsDir;
        if (k.isCtl()) return error.Perm;
        if (k == .mem_file) {
            const addr = valueOf(h) +% offset;
            return dp.d.readMem(addr, buf) catch |e| mapErr(e);
        }
        if (k == .maps) return dp.d.readMaps(offset, buf) catch |e| mapErr(e);
        const slot = dp.findSlot(h) orelse return error.Io;
        if (offset == 0) try dp.generate(tree, h, slot);
        if (offset >= slot.len) return 0;
        const off: usize = @intCast(offset);
        const n = @min(buf.len, slot.len - off);
        @memcpy(buf[0..n], slot.buf[off..][0..n]);
        return n;
    }

    fn write(dp: *DebugProvider, tree: Tree, h: Handle, offset: u64, data: []const u8) Error!usize {
        _ = tree;
        const k = kindOf(h);
        if (k.isDir()) return error.IsDir;
        switch (k) {
            .mem_file => {
                const addr = valueOf(h) +% offset;
                return dp.d.writeMem(addr, data) catch |e| mapErr(e);
            },
            .bp_ctl, .panic_ctl => {
                const cmd = std.mem.trim(u8, data, " \t\r\n\x00");
                if (!std.mem.eql(u8, cmd, "continue")) return error.Unsupported;
                if (k == .bp_ctl) {
                    dp.d.resumeThread(@intCast(valueOf(h))) catch |e| return mapErr(e);
                } else {
                    dp.d.panicContinue() catch |e| return mapErr(e);
                }
                return data.len;
            },
            else => return error.Perm,
        }
    }

    // -- snapshots ---------------------------------------------------------

    fn findSlot(dp: *DebugProvider, h: Handle) ?*Slot {
        for (&dp.slots) |*s| if (s.refs > 0 and s.handle == h) return s;
        return null;
    }

    fn takeSlot(dp: *DebugProvider, h: Handle) ?*Slot {
        if (dp.findSlot(h)) |s| {
            s.refs += 1;
            return s;
        }
        for (&dp.slots) |*s| if (s.refs == 0) {
            s.* = .{ .handle = h, .refs = 1 };
            return s;
        };
        return null;
    }

    fn releaseSlot(_: *DebugProvider, s: *Slot) void {
        s.refs -= 1;
    }

    /// (Re)generates the text of `h` into `slot`. A text that does not fit is
    /// truncated, not an error.
    fn generate(dp: *DebugProvider, tree: Tree, h: Handle, slot: *Slot) Error!void {
        var w: Writer = .fixed(&slot.buf);
        slot.len = 0;
        dp.render(tree, h, &w) catch |e| switch (e) {
            error.WriteFailed => {},
            else => return mapErr(e),
        };
        slot.len = @intCast(w.buffered().len);
    }

    fn render(dp: *DebugProvider, tree: Tree, h: Handle, w: *Writer) debug.Error!void {
        const d = dp.d;
        const v = valueOf(h);
        switch (kindOf(h)) {
            .readme => w.writeAll(readmeFor(tree)) catch return error.WriteFailed,
            .thread_name => try d.threadName(@intCast(v), w),
            .thread_stat => try d.threadStat(@intCast(v), w),
            .thread_stack => try d.threadStack(@intCast(v), w),
            .thread_regs => try d.threadRegs(@intCast(v), w),
            .addr_file => try d.resolveAddr(@intCast(v), w),
            .hex_file => try d.hexdump(@intCast(v), hex_bytes, w),
            .bp_stack => try d.pausedStack(@intCast(v), w),
            .bp_regs => try d.pausedRegs(@intCast(v), w),
            .panic_message => try d.panicMessage(w),
            .panic_stack => try d.panicStack(w),
            else => unreachable,
        }
    }

    fn mapErr(e: debug.Error) Error {
        return switch (e) {
            error.NoThread, error.NotPaused, error.NoPanic => error.NotFound,
            error.Unsupported => error.Unsupported,
            error.WriteFailed => error.NoSpace,
            error.Timeout, error.Busy, error.Unmapped, error.Unexpected, error.AlreadyInitialized, error.InvalidOptions => error.Io,
        };
    }
};

// ---------------------------------------------------------------------------
// Tests (through the core's in-memory harness)
// ---------------------------------------------------------------------------

const testing = std.testing;

const TestCfg: core.Config = .{ .name = "dbgtest", .msize = 8192, .max_fids = 16, .max_providers = 6, .snapshot_slots = 2, .snapshot_bytes = 512 };
const TS = core.Server(TestCfg);

test "debug provider: threads, addr, mem, hex, breakpoints, panic through the core" {
    var text_buf: [16 * 1024]u8 = undefined;
    var d: debug.Debug = undefined;
    try d.init(.{ .io = testing.io, .text_buf = &text_buf });
    defer d.deinit();
    var dp: DebugProvider = undefined;
    dp.init(&d);

    var dummy: u8 = 0;
    var shared: TS.Shared = .init(&dummy);
    try dp.mountAll(&shared);
    var storage: TS.Storage = undefined;
    var h: TS.Harness = undefined;
    try h.init(&shared, &storage);
    defer h.deinit();

    // /threads lists tids only, among them this thread.
    const names = try h.listPath(&.{"threads"});
    defer TS.Harness.freeNames(names);
    try testing.expect(names.len >= 1);
    try testing.expect(!TS.Harness.hasName(names, "README"));
    const no_readme = try h.ok(.{ .walk = .{ .fid = 0, .newfid = 7, .names = &.{ "threads", "README" } } });
    try testing.expectEqual(@as(u16, 1), no_readme.walk.nwqid);
    var tid_buf: [16]u8 = undefined;
    const tid = try std.fmt.bufPrint(&tid_buf, "{d}", .{std.os.linux.gettid()});
    try testing.expect(TS.Harness.hasName(names, tid));

    // Own stack names this test function's file.
    const stack = try h.readPath(&.{ "threads", tid, "stack" });
    defer testing.allocator.free(stack);
    try testing.expect(std.mem.indexOf(u8, stack, "#0 0x") != null);

    // /addr/<hex> of a function here resolves to this file.
    var addr_buf: [32]u8 = undefined;
    const addr_name = try std.fmt.bufPrint(&addr_buf, "{x}", .{@intFromPtr(&DebugProvider.parseTid)});
    const resolved = try h.readPath(&.{ "addr", addr_name });
    defer testing.allocator.free(resolved);
    try testing.expect(std.mem.indexOf(u8, resolved, "provider.zig") != null);
    const partial = try h.ok(.{ .walk = .{ .fid = 0, .newfid = 5, .names = &.{ "addr", "zzz" } } });
    try testing.expectEqual(@as(u16, 1), partial.walk.nwqid);
    try h.walkTo(5, &.{"addr"});
    try h.expectFail(.{ .walk = .{ .fid = 5, .newfid = 6, .names = &.{"zzz"} } }, "file does not exist");
    _ = try h.ok(.{ .clunk = .{ .fid = 5 } });

    // /mem/<hex> reads and writes live memory; unmapped is an error.
    var cell: [8]u8 = "abcdefgh".*;
    var mem_buf: [32]u8 = undefined;
    const mem_name = try std.fmt.bufPrint(&mem_buf, "{x}", .{@intFromPtr(&cell)});
    try h.walkTo(1, &.{ "mem", mem_name });
    _ = try h.ok(.{ .open = .{ .fid = 1, .mode = cloud9.ordwr } });
    const r = try h.ok(.{ .read = .{ .fid = 1, .offset = 2, .count = 4 } });
    try testing.expectEqualStrings("cdef", r.read);
    _ = try h.ok(.{ .write = .{ .fid = 1, .offset = 0, .data = "XY" } });
    try testing.expectEqualStrings("XYcdefgh", &cell);
    _ = try h.ok(.{ .clunk = .{ .fid = 1 } });
    try h.walkTo(2, &.{ "mem", "8" });
    _ = try h.ok(.{ .open = .{ .fid = 2, .mode = cloud9.oread } });
    try h.expectFail(.{ .read = .{ .fid = 2, .offset = 0, .count = 4 } }, "i/o error");
    _ = try h.ok(.{ .clunk = .{ .fid = 2 } });
    const maps = try h.readPath(&.{ "mem", "maps" });
    defer testing.allocator.free(maps);
    try testing.expect(std.mem.indexOf(u8, maps, "r-xp") != null or std.mem.indexOf(u8, maps, "r--p") != null);

    // /hex/<hex> is a hexdump.
    const hex = try h.readPath(&.{ "hex", mem_name });
    defer testing.allocator.free(hex);
    try testing.expect(std.mem.indexOf(u8, hex, "XYcdefgh") != null);

    // Nothing paused, no panic.
    const bps = try h.listPath(&.{"breakpoints"});
    defer TS.Harness.freeNames(bps);
    try testing.expectEqual(@as(usize, 0), bps.len);
    const msg = try h.readPath(&.{ "panic", "message" });
    defer testing.allocator.free(msg);
    try testing.expectEqualStrings("", msg);
    try h.walkTo(3, &.{ "panic", "ctl" });
    _ = try h.ok(.{ .open = .{ .fid = 3, .mode = cloud9.owrite } });
    try h.expectFail(.{ .write = .{ .fid = 3, .offset = 0, .data = "continue" } }, "file does not exist");
    try h.expectFail(.{ .write = .{ .fid = 3, .offset = 0, .data = "bogus" } }, "not supported");
    _ = try h.ok(.{ .clunk = .{ .fid = 3 } });

    // Snapshot slots are released on clunk: open more files than slots, sequentially.
    for (0..4) |_| {
        const t = try h.readPath(&.{ "threads", tid, "name" });
        testing.allocator.free(t);
    }
    for (&dp.slots) |s| try testing.expectEqual(@as(u32, 0), s.refs);
}

test "handle encoding round-trips" {
    const h = mk(.mem_file, 0x7fff_dead_beef);
    try testing.expectEqual(Kind.mem_file, kindOf(h));
    try testing.expectEqual(@as(u64, 0x7fff_dead_beef), valueOf(h));
    try testing.expect(h < (1 << 56));
    try testing.expectEqual(@as(?u64, null), DebugProvider.parseHex("1_0"));
    try testing.expectEqual(@as(?u64, 0x10), DebugProvider.parseHex("0x10"));
    try testing.expectEqual(@as(?u32, null), DebugProvider.parseTid("+5"));
}