const std = @import("std");
const manifest = @import("build.zig.zon");

pub fn build(b: *std.Build) void {
    const target = b.standardTargetOptions(.{});
    const optimize = b.standardOptimizeOption(.{});
    // What `parcel --version` says: the version a `release: X.Y.Z` commit
    // sets in build.zig.zon, unless the build names another.
    const options = b.addOptions();
    options.addOption([]const u8, "version", b.option([]const u8, "version", "The version parcel reports") orelse
        manifest.version);

    // siv-static links libsiv.a into the program, so it runs from zig-out
    // with no libsiv.so beside it; libsiv.so also links with LLD, which bs
    // does not. siv-webview stays off until a view needs HTML mail.
    const siv = b.dependency("siv", .{ .target = target, .optimize = optimize, .webview = false });
    const siv_mod = siv.module("siv-static");
    // Local time for the dates mail shows, from the system's zone files.
    const zeit = b.dependency("zeit", .{ .target = target, .optimize = optimize });
    const mod = b.createModule(.{
        .root_source_file = b.path("src/main.zig"),
        .target = target,
        .optimize = optimize,
        .imports = &.{
            .{ .name = "siv", .module = siv_mod },
            .{ .name = "zeit", .module = zeit.module("zeit") },
        },
    });

    mod.addOptions("build_options", options);
    // HTTP, on siv's event loop (src/Http.zig).
    mod.linkSystemLibrary("curl", .{});
    const exe = b.addExecutable(.{ .name = "parcel", .root_module = mod });
    b.installArtifact(exe);
    // The desktop entry and its icon, named for the app_id the window
    // gives itself, so launchers and compositors match them to it.
    b.installFile("data/dev.rockorager.parcel.desktop", "share/applications/dev.rockorager.parcel.desktop");
    b.installFile("data/dev.rockorager.parcel.svg", "share/icons/hicolor/scalable/apps/dev.rockorager.parcel.svg");
    // The licences of what the binary compiles in, which it must carry:
    // libsiv's, then zeit's, parcel's one Zig dependency of its own. curl
    // is linked from the system.
    const rule: [78]u8 = @splat('=');
    const zeit_title = b.addWriteFiles().add("zeit-title", "\n" ++ rule ++
        "\nzeit (MIT)\nhttps://github.com/rockorager/zeit\n" ++ rule ++ "\n\n");
    const notices = b.addSystemCommand(&.{"cat"});
    notices.addFileArg(siv.namedLazyPath("notices"));
    notices.addFileArg(zeit_title);
    notices.addFileArg(zeit.path("LICENSE"));
    b.getInstallStep().dependOn(
        &b.addInstallFileWithDir(notices.captureStdOut(.{}), .prefix, "share/doc/parcel/NOTICES").step,
    );

    const run = b.addRunArtifact(exe);
    run.addPassthruArgs();
    b.step("run", "Run parcel").dependOn(&run.step);

    // Mailbox-view prototypes (src/proto): `zig build proto -- NAME` runs
    // one, and `zig build proto-shots` renders them all headless to PNG.
    const proto_mod = b.createModule(.{
        .root_source_file = b.path("src/proto/main.zig"),
        .target = target,
        .optimize = optimize,
        .imports = &.{.{ .name = "siv", .module = siv_mod }},
    });
    const proto = b.addExecutable(.{ .name = "parcel-proto", .root_module = proto_mod });
    // Built with a development build of parcel, so it keeps compiling, but
    // not installed with it; a release build, which ships parcel alone,
    // leaves it out.
    if (optimize == .debug) b.getInstallStep().dependOn(&proto.step);
    const run_proto = b.addRunArtifact(proto);
    run_proto.addPassthruArgs();
    b.step("proto", "Run a mailbox-view prototype (no NAME lists them)").dependOn(&run_proto.step);

    const image = b.dependency("image", .{ .target = target, .optimize = optimize });
    const shots = b.addExecutable(.{
        .name = "parcel-proto-shots",
        .root_module = b.createModule(.{
            .root_source_file = b.path("src/proto/shots.zig"),
            .target = target,
            .optimize = optimize,
            .imports = &.{
                .{ .name = "siv", .module = siv_mod },
                .{ .name = "image", .module = image.module("image") },
            },
        }),
    });
    const run_shots = b.addRunArtifact(shots);
    run_shots.addDirectoryArg(b.path("zig-out/shots"));
    run_shots.addPassthruArgs();
    run_shots.has_side_effects = true;
    b.step("proto-shots", "Render the prototypes to zig-out/shots (NAME... picks some)").dependOn(&run_shots.step);

    // The tests run siv on its headless backend, so they need no display.
    const filters = b.option([]const []const u8, "test-filter", "Run only tests whose names contain it") orelse &.{};
    const test_step = b.step("test", "Run the tests");
    for ([_]*std.Build.Module{ mod, proto_mod }) |m| {
        const tests = b.addTest(.{ .root_module = m, .filters = filters });
        test_step.dependOn(&b.addRunArtifact(tests).step);
    }
}