const std = @import("std");

// Although this function looks imperative, note that its job is to
// declaratively construct a build graph that will be executed by an external
// runner.
pub fn build(b: *std.Build) void {
    // Standard target options allows the person running `zig build` to choose
    // what target to build for. Here we do not override the defaults, which
    // means any target is allowed, and the default is native. Other options
    // for restricting supported target set are available.
    const target = b.standardTargetOptions(.{});

    // Standard optimization options allow the person running `zig build` to select
    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
    // set a preferred release mode, allowing the user to decide how to optimize.
    const optimize = b.standardOptimizeOption(.{});


    const exe = b.addExecutable(.{
        .name = "zig-gst",
        .root_source_file = b.path("src/main.zig"),
        .target = target,
        .optimize = optimize,
    });

    // These environment vars are set with the `nix develop` command
    const gst_dev_path = b.graph.env_map.get("GST_DEV_PATH");  
    const glib_dev_path = b.graph.env_map.get("GLIB_DEV_PATH");
    const glib_path = b.graph.env_map.get("GLIB_PATH");

    if (gst_dev_path == null) {
        std.debug.panic("GST_DEV_PATH environment variable was not set. Has the nix flake been updated? This should point at the gstreamer.XXX-dev folder", .{});
    }

    if (glib_dev_path == null) {
        std.debug.panic("GLIB_DEV_PATH environment variable was not set. Has the nix flake been updated? This should point at the glib.XXX-dev folder", .{});
    }

    if (glib_path == null) {
        std.debug.panic("GLIB_PATH environment variable was not set. Has the nix flake been updated? This should point at the glib.XXX folder", .{});
    }

    exe.linkSystemLibrary("c");
    exe.addIncludePath(.{ .cwd_relative = b.fmt("{s}/include/gstreamer-1.0", .{gst_dev_path.?}) });     // not sure why both are needed, but 
    exe.addIncludePath(.{ .cwd_relative = b.fmt("{s}/include/gstreamer-1.0/gst", .{gst_dev_path.?}) }); // it won't compile without them
    exe.addIncludePath(.{ .cwd_relative = b.fmt("{s}/include/glib-2.0", .{glib_dev_path.?}) });
    exe.addIncludePath(.{ .cwd_relative = b.fmt("{s}/lib/glib-2.0/include", .{glib_path.?}) });

    exe.addIncludePath(.{ .cwd_relative = "/usr/include/hailo" });
    // exe.addLibraryPath(.{ .cwd_relative = "/usr/lib"});
    exe.addLibraryPath(.{ .cwd_relative = "/home/nixolas/Documents/hailort/build/hailort/libhailort/src"});
    exe.linkSystemLibrary("hailort");


    exe.linkSystemLibrary("gstreamer-1.0");
    exe.linkSystemLibrary("glib-2.0");
    exe.linkSystemLibrary("gobject-2.0");

    // This declares intent for the executable to be installed into the
    // standard location when the user invokes the "install" step (the default
    // step when running `zig build`).
    b.installArtifact(exe);

    // This *creates* a Run step in the build graph, to be executed when another
    // step is evaluated that depends on it. The next line below will establish
    // such a dependency.
    const run_cmd = b.addRunArtifact(exe);

    // By making the run step depend on the install step, it will be run from the
    // installation directory rather than directly from within the cache directory.
    // This is not necessary, however, if the application depends on other installed
    // files, this ensures they will be present and in the expected location.
    run_cmd.step.dependOn(b.getInstallStep());

    // This allows the user to pass arguments to the application in the build
    // command itself, like this: `zig build run -- arg1 arg2 etc`
    if (b.args) |args| {
        run_cmd.addArgs(args);
    }

    // This creates a build step. It will be visible in the `zig build --help` menu,
    // and can be selected like this: `zig build run`
    // This will evaluate the `run` step rather than the default, which is "install".
    const run_step = b.step("run", "Run the app");
    run_step.dependOn(&run_cmd.step);
}