const std = @import("std");

// this file creates auto generated static resource installers for
// embedded shaders.
//
// when building with -Dstatic_build shaders are instead not loaded from the file system
// but instead embedded into the binary

pub fn main() !void {
    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
    defer arena.deinit();
    const allocator = arena.allocator();

    // Get output filename from build system
    const args = try std.process.argsAlloc(allocator);
    if (args.len < 3) @panic("Missing output filename");
    const out_path = args[1];

    // Generate a startup module function that invokes
    // startup module for each zig function
    // and generates an api
    var writer = std.ArrayList(u8){};

    // const content_path = args[2];
    // std.debug.print("content path: {s}\n", .{content_path});

    // check the content directory and search for all _spv files

    var dir = try std.fs.cwd().openDir("content/_shaders", .{ .iterate = true });
    defer dir.close();

    _ = try writer.appendSlice(allocator,
        \\ pub const core = @import("core").module;
        \\
        \\ pub fn installStaticResources() !void {
        \\ 
    );

    var shaderFileEmbeds = std.ArrayList([]const u8){};

    var walker = dir.iterate();
    while (try walker.next()) |shaderType| {
        // std.debug.print("Walk: {s}\n", .{shaderType.name});
        if (shaderType.kind == .directory) {
            var d2 = try dir.openDir(shaderType.name, .{ .iterate = true });
            defer d2.close();
            var w2 = d2.iterate();
            while (try w2.next()) |shaderName| {
                const shaderPath = try std.fmt.allocPrint(allocator, "_shaders/{s}/{s}", .{ shaderType.name, shaderName.name });
                // std.debug.print("mounted path: {s} => {s}\n", .{ shaderPath, shaderName.name });
                try writer.print(
                    allocator,
                    "{{ const embedded align(8) = @embedFile(\"{s}\").*;\n_ = try core.fs().installFileBytesMount(\"{s}\", @constCast(&embedded), true);}}\n",
                    .{ shaderName.name, shaderPath },
                );
                try shaderFileEmbeds.append(allocator, shaderName.name);
            }
        }
    }

    _ = try writer.appendSlice(allocator,
        \\ }
    );

    try writer.print(allocator, "const std = @import(\"std\");", .{});

    // Write to specified output file
    // Open or create the file for writing (overwrites if it exists)
    const file = try std.fs.cwd().createFile(out_path, .{});
    defer file.close();

    try writer.append(allocator, 0);

    var ast = try std.zig.Ast.parse(allocator, @as([:0]const u8, @ptrCast(writer.items[0 .. writer.items.len - 1])), .zig);

    // std.debug.print("output=\n{s}", .{content.items[0 .. content.items.len - 1]});
    defer ast.deinit(allocator);
    const out = try ast.renderAlloc(allocator);

    // Write the content to the file
    try file.writeAll(out);
}