const std = @import("std");

pub fn build(b: *std.Build) void {
    const target = b.standardTargetOptions(.{});
    const optimize = b.standardOptimizeOption(.{});

    // libghostty-vt provides the terminal emulator core: escape sequence
    // parsing, screen/scrollback state, and input encoding. Everything above
    // it (PTY, rendering, windowing) is ours.
    const ghostty = b.dependency("ghostty", .{
        .target = target,
        .optimize = optimize,
    });

    // GTK4/libadwaita bindings. This is the same generated binding set
    // Ghostty uses for its Linux apprt, so it matches the GObject
    // introspection data of the GTK we link against.
    const gobject = b.dependency("gobject", .{
        .target = target,
        .optimize = optimize,
    });

    const exe = b.addExecutable(.{
        .name = "playpen",
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/main.zig"),
            .target = target,
            .optimize = optimize,
            .link_libc = true,
        }),
    });

    exe.root_module.addImport("ghostty-vt", ghostty.module("ghostty-vt"));

    // The symbolic icons the app names are compiled into the binary, so that
    // showing a terminal or web-browser glyph doesn't depend on which icon
    // theme the host has installed. glib-compile-resources comes from the same
    // Nix shell as GTK itself; the compiled bundle is embedded by src/icons.zig
    // and registered at startup.
    const gresource = b.addSystemCommand(&.{"glib-compile-resources"});
    gresource.addArg("--sourcedir");
    gresource.addDirectoryArg(b.path("assets/icons"));
    gresource.addArg("--target");
    const icons_gresource = gresource.addOutputFileArg("icons.gresource");
    gresource.addFileArg(b.path("assets/icons/icons.gresource.xml"));
    exe.root_module.addAnonymousImport("icons.gresource", .{
        .root_source_file = icons_gresource,
    });

    // The review pane's UI. It is a React app (see `web/`), built by Vite here so
    // the bundle embedded in the binary can never be older than the source it
    // came from, and embedded rather than installed alongside so a review pane
    // is a web view pointed at this process and nothing else.
    //
    // The four filenames are pinned in `web/vite.config.ts` precisely so they
    // can be named at compile time; `src/review/assets.zig` is the other half of
    // that agreement.
    const web_build = b.addSystemCommand(&.{ "npm", "run", "--silent", "build", "--" });
    web_build.setCwd(b.path("web"));
    web_build.setName("vite build (review UI)");
    web_build.addArg("--outDir");
    const web_dist = web_build.addOutputDirectoryArg("dist");
    web_build.addArg("--emptyOutDir");

    // Vite is not told what its inputs are, so the Run step has to be. Without
    // this the bundle is cached against its argv alone and editing the UI would
    // rebuild nothing; with it, `zig build` after a `.tsx` edit does the right
    // thing and `zig build` after a `.zig` edit does not re-run npm.
    addWebInputs(b, web_build);

    exe.root_module.addAnonymousImport("review-index.html", .{
        .root_source_file = web_dist.path(b, "index.html"),
    });
    exe.root_module.addAnonymousImport("review-app.js", .{
        .root_source_file = web_dist.path(b, "assets/app.js"),
    });
    exe.root_module.addAnonymousImport("review-app.css", .{
        .root_source_file = web_dist.path(b, "assets/app.css"),
    });
    exe.root_module.addAnonymousImport("review-favicon.svg", .{
        .root_source_file = web_dist.path(b, "favicon.svg"),
    });

    const gobject_imports = .{
        .{ "adw", "adw1" },
        .{ "cairo", "cairo1" },
        .{ "gdk", "gdk4" },
        .{ "gio", "gio2" },
        .{ "glib", "glib2" },
        .{ "glibunix", "glibunix2" },
        .{ "gobject", "gobject2" },
        .{ "gtk", "gtk4" },
        .{ "pango", "pango1" },
        .{ "pangocairo", "pangocairo1" },
    };
    inline for (gobject_imports) |import| {
        const name, const module = import;
        exe.root_module.addImport(name, gobject.module(module));
    }

    exe.root_module.linkSystemLibrary("gtk4", .{});
    exe.root_module.linkSystemLibrary("libadwaita-1", .{});

    // WebKitGTK backs the web panes. There are no generated bindings for it in
    // the zig-gobject set we use, so `src/webkit.zig` declares the handful of
    // C entry points we need by hand and this links them.
    exe.root_module.linkSystemLibrary("webkitgtk-6.0", .{});

    b.installArtifact(exe);

    const run_cmd = b.addRunArtifact(exe);
    run_cmd.step.dependOn(b.getInstallStep());
    if (b.args) |args| run_cmd.addArgs(args);
    b.step("run", "Run the app").dependOn(&run_cmd.step);

    // Tests are rooted at Layouts.zig rather than main.zig: the parts of this
    // app worth testing in isolation are the ones that are pure data — layout
    // parsing, parameter substitution, the `$(...)` expansion and the script
    // runner underneath it. Everything else is a widget tree, which wants a
    // display and a person looking at it.
    //
    // Rooting there also keeps the test binary off GTK entirely; Layouts.zig
    // and script.zig reach for GLib and nothing above it.
    const tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/Layouts.zig"),
            .target = target,
            .optimize = optimize,
            .link_libc = true,
        }),
    });
    tests.root_module.addImport("glib", gobject.module("glib2"));

    const test_step = b.step("test", "Run the tests");
    test_step.dependOn(&b.addRunArtifact(tests).step);

    // The session snapshot is its own root for the same reason, and is the same
    // kind of thing: a file the app writes and reads back, whose shape is worth
    // being sure about. It imports Layouts.zig for the node grammar the two
    // share, and needs libc for the one call GLib does not expose — see
    // `Snapshot.remove`.
    const snapshot_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/Snapshot.zig"),
            .target = target,
            .optimize = optimize,
            .link_libc = true,
        }),
    });
    snapshot_tests.root_module.addImport("glib", gobject.module("glib2"));
    test_step.dependOn(&b.addRunArtifact(snapshot_tests).step);

    // The directory field's rules are their own root, for the same reason as
    // the layouts file: which directory a half-typed path names, which entries
    // in it are offered and how far they agree is text and filesystem, and the
    // popover above it is the part that wants a display. It reaches GLib and
    // nothing else, so it tests without one.
    const paths_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/paths.zig"),
            .target = target,
            .optimize = optimize,
            .link_libc = true,
        }),
    });
    paths_tests.root_module.addImport("glib", gobject.module("glib2"));
    test_step.dependOn(&b.addRunArtifact(paths_tests).step);

    // The palette is the third root: a table of colors, the rules for
    // resolving one, and the CSS it is written out as. It reaches libghostty-vt
    // for the terminal's own default palette and nothing else, so it tests
    // without a display in the same way the two above do.
    const palette_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/palette.zig"),
            .target = target,
            .optimize = optimize,
        }),
    });
    palette_tests.root_module.addImport("ghostty-vt", ghostty.module("ghostty-vt"));
    test_step.dependOn(&b.addRunArtifact(palette_tests).step);

    // And a root for the settings file itself. `Settings.zig` reaches GLib for
    // where the file lives, but reading and writing its *contents* is pure
    // enough to test — which is what these cover, since the palette overrides
    // are a nested object whose shape one launch has to agree with the next on.
    const settings_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/Settings.zig"),
            .target = target,
            .optimize = optimize,
            .link_libc = true,
        }),
    });
    settings_tests.root_module.addImport("glib", gobject.module("glib2"));
    settings_tests.root_module.addImport("ghostty-vt", ghostty.module("ghostty-vt"));
    test_step.dependOn(&b.addRunArtifact(settings_tests).step);

    // Paste safety is its own root, and for a sharper reason than the rest:
    // when it says no it says so silently — the terminal simply does not
    // receive what you pasted — so the rule that decides has to be checkable
    // without a display. It reaches libghostty-vt for the encoder and nothing
    // else; the clipboard round trip around it is GTK's and stays in
    // `Terminal.zig`.
    const paste_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/paste.zig"),
            .target = target,
            .optimize = optimize,
        }),
    });
    paste_tests.root_module.addImport("ghostty-vt", ghostty.module("ghostty-vt"));
    test_step.dependOn(&b.addRunArtifact(paste_tests).step);

    // The shortcut table is its own root for the same reason: chords are parsed
    // from text, written back out as text, and looked up by a key press, and
    // all three are pure data. It reaches libghostty-vt for the key enum and
    // nothing else, which is what keeps it — and the settings tests above, which
    // import it — off GTK.
    const shortcut_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/shortcuts.zig"),
            .target = target,
            .optimize = optimize,
        }),
    });
    shortcut_tests.root_module.addImport("ghostty-vt", ghostty.module("ghostty-vt"));
    test_step.dependOn(&b.addRunArtifact(shortcut_tests).step);

    // A second root for the same reason, one step further out: `emoji.zig` is a
    // table and a search over it, and it imports nothing at all. It cannot hang
    // off the root above because a test binary has exactly one root, and
    // Layouts.zig has no reason to reach for the emoji table.
    // The review server's two testable halves. `git.zig` is git's own output
    // formats and the rule for picking a base ref — text in, text out. `Store.zig`
    // is the review file, whose round trip is the one piece of this that has to
    // survive the process. Neither reaches GTK, so both run without a display;
    // the HTTP layer above them wants a socket and a browser, which is a
    // different kind of test than this project has.
    const git_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/review/git.zig"),
            .target = target,
            .optimize = optimize,
            .link_libc = true,
        }),
    });
    test_step.dependOn(&b.addRunArtifact(git_tests).step);

    const store_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/review/Store.zig"),
            .target = target,
            .optimize = optimize,
            .link_libc = true,
        }),
    });
    test_step.dependOn(&b.addRunArtifact(store_tests).step);

    // The mute rules are their own root. Whether a tab is silent at this instant,
    // and what its row menu says about that, is arithmetic on a deadline — and
    // it is the half of notifications that can be wrong without anyone noticing,
    // since the symptom is a popup that didn't arrive. It reaches gio to hand a
    // notification to the session, which is the part these tests leave alone.
    const notify_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/notify.zig"),
            .target = target,
            .optimize = optimize,
            .link_libc = true,
        }),
    });
    notify_tests.root_module.addImport("gio", gobject.module("gio2"));
    notify_tests.root_module.addImport("glib", gobject.module("glib2"));
    test_step.dependOn(&b.addRunArtifact(notify_tests).step);

    const emoji_tests = b.addTest(.{
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/emoji.zig"),
            .target = target,
            .optimize = optimize,
        }),
    });
    test_step.dependOn(&b.addRunArtifact(emoji_tests).step);
}

/// Declare every file the Vite build reads as an input of that build step.
///
/// Zig hashes a `Run` step's file *arguments*, but a directory passed as an
/// argument is hashed by path and not by contents — so the source tree has to be
/// enumerated here, at configure time, for the cache to be honest about when the
/// bundle is stale.
///
/// `node_modules` is deliberately not walked. It is tens of thousands of files
/// whose contents are already pinned by `package-lock.json`, which *is* listed.
fn addWebInputs(b: *std.Build, run: *std.Build.Step.Run) void {
    for ([_][]const u8{
        "web/index.html",
        "web/package.json",
        "web/package-lock.json",
        "web/tsconfig.json",
        "web/vite.config.ts",
    }) |file| {
        run.addFileInput(b.path(file));
    }

    const io = b.graph.io;
    for ([_][]const u8{ "web/src", "web/public" }) |root| {
        var dir = b.build_root.handle.openDir(io, root, .{ .iterate = true }) catch continue;
        defer dir.close(io);

        var walker = dir.walk(b.allocator) catch continue;
        defer walker.deinit();
        while (walker.next(io) catch null) |entry| {
            if (entry.kind != .file) continue;
            run.addFileInput(b.path(b.pathJoin(&.{ root, entry.path })));
        }
    }
}