const std = @import("std");

pub fn show_usage() void {
    std.debug.print("Usage: zig build generate <sample-rate> <sample-count> <filename>\n", .{});
}

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    const allocator = gpa.allocator();
    defer _ = gpa.deinit();

    var args = try std.process.argsWithAllocator(allocator);
    defer args.deinit();

    _ = args.next();

    const sample_rate_str = args.next() orelse {
        show_usage();
        std.process.exit(1);
    };

    const sample_count_str = args.next() orelse {
        show_usage();
        std.process.exit(1);
    };

    const filename = args.next() orelse {
        show_usage();
        std.process.exit(1);
    };

    const sample_rate = try std.fmt.parseFloat(f64, sample_rate_str);
    const sample_count = try std.fmt.parseInt(u32, sample_count_str, 10);

    const f = try std.fs.cwd().createFile(filename, .{ .exclusive = true });
    defer f.close();

    for (0..sample_count) |i| {
        const i_f64: f64 = @floatFromInt(i);
        const sample: f64 = std.math.sin( i_f64 / sample_rate * std.math.pi * 2 ) * 10;
        const sample_bytes = std.mem.toBytes(sample);
        try f.writeAll(&sample_bytes);
    }
}