1 files changed, 41 insertions, 0 deletions
diff --git a/aoc25/tools/download_input.zig b/aoc25/tools/download_input.zig
new file mode 100644
index 0000000..3fae78c
--- /dev/null
+++ b/aoc25/tools/download_input.zig
@@ -0,0 +1,41 @@
+const std = @import("std");
+
+pub fn main() !void {
+    std.debug.print("Downloading input from adventofcode.com\n", .{});
+
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena.deinit();
+    const allocator = arena.allocator();
+
+    const args = try std.process.argsAlloc(allocator);
+
+    if (args.len != 3) return error.InvalidArguments;
+
+    const day = try std.fmt.parseInt(u32, args[1], 10);
+    const output_file_path = args[2];
+
+    var output_file = try std.fs.cwd().createFile(output_file_path, .{});
+    defer output_file.close();
+    var output_buffer: [4096]u8 = undefined;
+    var output_writer = output_file.writer(&output_buffer);
+    var output = &output_writer.interface;
+
+    const url = try std.fmt.allocPrint(allocator, "https://adventofcode.com/2025/day/{}/input", .{day});
+    defer allocator.free(url);
+    const session_cookie_header = try std.fmt.allocPrint(allocator, "session={s}", .{
+        std.posix.getenv("AOC_SESSION") orelse return error.MissingAocSession,
+    });
+    defer allocator.free(session_cookie_header);
+    var client = std.http.Client{ .allocator = allocator };
+    const result = try client.fetch(.{
+        .location = .{ .url = url },
+        .response_writer = output,
+        .extra_headers = &[_]std.http.Header{
+            .{ .name = "Cookie", .value = session_cookie_header },
+        },
+    });
+    if (result.status != .ok) return error.InvalidStatusCode;
+
+    try output.flush();
+    return std.process.cleanExit();
+}