//! Build fragment for 9ns: mount a 9P2000 tree into a fresh mount
//! namespace via FUSE and run a program in it (Linux only, no libc). It is
//! `@import`ed by the root build.zig and called with the root builder, so
//! every `b.path(...)` here is relative to the cloud9 root (hence the
//! `9ns/` prefix), every option is defined by the root (no
//! `standardTargetOptions` here) and every step it registers lands in the
//! root's step list under the `9ns` prefix.
//!
//! Steps: 9ns, 9ns-test, 9ns-itest, 9ns-adv.
const std = @import("std");

/// What the root passes in. The root owns target/optimize resolution and the
/// cloud9 module; the integration suites also need a 9P server to mount,
/// which is the 9proc demo built by the sibling fragment.
pub const Context = struct {
    target: std.Build.ResolvedTarget,
    optimize: std.builtin.OptimizeMode,
    cloud9: *std.Build.Module,
    /// The `9proc-demo` server; null when 9proc is disabled, in
    /// which case the end-to-end steps exist but fail with a notice.
    proc_demo: ?*std.Build.Step.Compile,
};

pub const Artifacts = struct {
    /// The 9ns executable (also installed by the plain `zig build`).
    exe: *std.Build.Step.Compile,
    /// `9ns-test`, `9ns-itest`, `9ns-adv`.
    test_step: *std.Build.Step,
    itest_step: *std.Build.Step,
    adv_step: *std.Build.Step,
};

pub fn add(b: *std.Build, ctx: Context) Artifacts {
    const target = ctx.target;
    const optimize = ctx.optimize;
    std.debug.assert(target.result.os.tag == .linux); // the root only enables 9ns on Linux

    const ns_mod = b.createModule(.{
        .root_source_file = b.path("9ns/src/main.zig"),
        .target = target,
        .optimize = optimize,
        .imports = &.{.{ .name = "cloud9", .module = ctx.cloud9 }},
    });
    const ns = b.addExecutable(.{ .name = "9ns", .root_module = ns_mod });
    const install = b.addInstallArtifact(ns, .{});
    b.getInstallStep().dependOn(&install.step);
    b.step("9ns", "Build and install only the 9ns binary").dependOn(&install.step);

    // Unit tests: protocol structs, session, bridge, namespace helpers (main.zig
    // reaches every module).
    const test_step = b.step("9ns-test", "Run 9ns's unit tests");
    test_step.dependOn(&b.addRunArtifact(b.addTest(.{ .root_module = ns_mod })).step);

    // End-to-end suites: real namespaces, real FUSE, a real 9P server.
    // integration.sh: the single-connection transports; mntgen.sh: the
    // posted-registry multi-server mode (registry servers + lazy dial).
    const itest = b.step("9ns-itest", "Run 9ns/test/integration.sh and 9ns/test/mntgen.sh (needs unprivileged user namespaces and /dev/fuse)");
    const adv = b.step("9ns-adv", "Run 9ns/test/adversarial.sh (hostile servers, namespaces, stress; several minutes)");
    const demo = ctx.proc_demo orelse {
        const fail = b.addFail("9ns-itest and 9ns-adv need the 9proc-demo server (build with -D9proc=true)");
        itest.dependOn(&fail.step);
        adv.dependOn(&fail.step);
        return .{ .exe = ns, .test_step = test_step, .itest_step = itest, .adv_step = adv };
    };
    inline for (.{ .{ itest, "integration" }, .{ itest, "mntgen" }, .{ adv, "adversarial" } }) |pair| {
        const run = b.addSystemCommand(&.{"bash"});
        run.addFileArg(b.path("9ns/test/" ++ pair[1] ++ ".sh"));
        run.addArtifactArg(ns);
        run.addArtifactArg(demo);
        pair[0].dependOn(&run.step);
    }
    return .{ .exe = ns, .test_step = test_step, .itest_step = itest, .adv_step = adv };
}