1 files changed, 90 insertions, 0 deletions
diff --git a/tools/update-patches.zig b/tools/update-patches.zig
new file mode 100644
index 0000000..618d2bf
--- /dev/null
+++ b/tools/update-patches.zig
@@ -0,0 +1,90 @@
+const std = @import("std");
+const print = std.debug.print;
+const string = []const u8;
+
+const cwd = std.fs.cwd();
+const Dir = std.fs.Dir;
+const Allocator = std.mem.Allocator;
+
+const EXERCISES_PATH = "exercises";
+const ANSWERS_PATH = "answers";
+const PATCHES_PATH = "patches/patches";
+
+// Heals all the exercises.
+fn heal(alloc: Allocator) !void {
+    try cwd.makePath(ANSWERS_PATH);
+
+    const org_path = try cwd.realpathAlloc(alloc, EXERCISES_PATH);
+    const patch_path = try cwd.realpathAlloc(alloc, PATCHES_PATH);
+    const healed_path = try cwd.realpathAlloc(alloc, ANSWERS_PATH);
+
+    var idir = try cwd.openIterableDir(EXERCISES_PATH, Dir.OpenDirOptions{});
+    defer idir.close();
+
+    var it = idir.iterate();
+    while (try it.next()) |entry| {
+
+        // create filenames
+        const healed_file = try concat(alloc, &.{ healed_path, "/", entry.name });
+        const patch_file = try concat(alloc, &.{ patch_path, "/", try patch_name(alloc, entry.name) });
+
+        // patch the file
+        const result = try std.ChildProcess.exec(.{
+            .allocator = alloc,
+            .argv = &.{ "patch", "-i", patch_file, "-o", healed_file, entry.name },
+            .cwd = org_path,
+        });
+
+        print("{s}", .{result.stderr});
+    }
+}
+
+// Creates new patch files for every exercise
+fn update(alloc: Allocator) !void {
+    const org_path = try cwd.realpathAlloc(alloc, EXERCISES_PATH);
+    const healed_path = try cwd.realpathAlloc(alloc, ANSWERS_PATH);
+    const patch_path = try cwd.realpathAlloc(alloc, PATCHES_PATH);
+
+    var idir = try cwd.openIterableDir(EXERCISES_PATH, Dir.OpenDirOptions{});
+    defer idir.close();
+
+    var it = idir.iterate();
+    while (try it.next()) |entry| {
+
+        // create diff
+        const org_file = try concat(alloc, &.{ org_path, "/", entry.name });
+        const healed_file = try concat(alloc, &.{ healed_path, "/", entry.name });
+        const result = try std.ChildProcess.exec(.{
+            .allocator = alloc,
+            .argv = &.{ "diff", org_file, healed_file },
+        });
+        std.debug.assert(result.term.Exited == 1);
+
+        // write diff to file
+        const patch_file = try concat(alloc, &.{ patch_path, "/", try patch_name(alloc, entry.name) });
+        var file = try std.fs.cwd().createFile(patch_file, .{ .read = false });
+        defer file.close();
+        try file.writer().print("{s}", .{result.stdout});
+    }
+}
+
+fn concat(alloc: Allocator, slices: []const string) !string {
+    const buf = try std.mem.concat(alloc, u8, slices);
+    return buf;
+}
+
+fn patch_name(alloc: Allocator, path: string) !string {
+    var filename = path;
+    const index = std.mem.lastIndexOfScalar(u8, path, '.') orelse return path;
+    if (index > 0) filename = path[0..index];
+    return try concat(alloc, &.{ filename, ".patch" });
+}
+
+pub fn main() !void {
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena.deinit();
+    const alloc = arena.allocator();
+
+    try heal(alloc);
+    try update(alloc);
+}