codecrafters submit [skip ci]

3 files changed, 50 insertions, 3 deletions

diff --git a/src/builtins.zig b/src/builtins.zig
index 8ce4a6f..4f8dfb8 100644
--- a/src/builtins.zig
+++ b/src/builtins.zig
@@ -181,3 +181,41 @@ pub fn executeHistoryWrite(stdout: anytype, file_path: []const u8, history_list:
         try file.writeAll("\n");
     }
 }
+
+pub fn executeHistoryAppend(stdout: anytype, file_path: []const u8, history_list: []const []const u8, last_written_index: *usize) !void {
+    // Open file in append mode, or create if doesn't exist
+    const file = std.fs.cwd().openFile(file_path, .{ .mode = .write_only }) catch |err| {
+        if (err == error.FileNotFound) {
+            // Create the file if it doesn't exist
+            const new_file = std.fs.cwd().createFile(file_path, .{}) catch {
+                try stdout.print("history: cannot write to {s}: error\n", .{file_path});
+                return;
+            };
+            defer new_file.close();
+
+            // Write all commands to new file
+            for (history_list) |cmd| {
+                try new_file.writeAll(cmd);
+                try new_file.writeAll("\n");
+            }
+            last_written_index.* = history_list.len;
+            return;
+        } else {
+            try stdout.print("history: cannot open {s}: error\n", .{file_path});
+            return;
+        }
+    };
+    defer file.close();
+
+    // Seek to end to append
+    try file.seekFromEnd(0);
+
+    // Append only new commands (commands after last_written_index)
+    const start_idx = last_written_index.*;
+    for (history_list[start_idx..]) |cmd| {
+        try file.writeAll(cmd);
+        try file.writeAll("\n");
+    }
+
+    last_written_index.* = history_list.len;
+}
diff --git a/src/main.zig b/src/main.zig
index 69b40e0..d373826 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -361,6 +361,8 @@ pub fn main() !void {
         history.deinit(allocator);
     }
 
+    var last_written_index: usize = 0;
+
     const stdout = std.fs.File.stdout();
 
     while (true) {
@@ -406,7 +408,7 @@ pub fn main() !void {
 
                 if (segments.items.len == 1) {
                     const parsed = parser.parseCommand(cmd);
-                    const result = try shell.executeCommand(allocator, stdout_iface, parsed.name, parsed.args, parsed.output_redirect, parsed.error_redirect, parsed.append_output, parsed.append_error, &history);
+                    const result = try shell.executeCommand(allocator, stdout_iface, parsed.name, parsed.args, parsed.output_redirect, parsed.error_redirect, parsed.append_output, parsed.append_error, &history, &last_written_index);
                     if (result == .exit_shell) break;
                 } else {
                     const result = try shell.executePipeline(allocator, stdout_iface, segments.items);
@@ -415,7 +417,7 @@ pub fn main() !void {
             } else {
                 const parsed = parser.parseCommand(cmd);
 
-                const result = try shell.executeCommand(allocator, stdout_iface, parsed.name, parsed.args, parsed.output_redirect, parsed.error_redirect, parsed.append_output, parsed.append_error, &history);
+                const result = try shell.executeCommand(allocator, stdout_iface, parsed.name, parsed.args, parsed.output_redirect, parsed.error_redirect, parsed.append_output, parsed.append_error, &history, &last_written_index);
 
                 if (result == .exit_shell) break;
             }
diff --git a/src/shell.zig b/src/shell.zig
index 5a848af..d3f75ec 100644
--- a/src/shell.zig
+++ b/src/shell.zig
@@ -20,11 +20,12 @@ pub fn executeCommand(
     append_output: ?[]const u8,
     append_error: ?[]const u8,
     history: *std.ArrayList([]const u8),
+    last_written_index: *usize,
 ) !builtins.CommandResult {
     if (std.mem.eql(u8, cmd_name, "exit")) return builtins.executeExit();
 
     if (std.mem.eql(u8, cmd_name, "history")) {
-        // Check if args contain -r or -w flag for reading/writing file
+        // Check if args contain -r, -w, or -a flag for reading/writing/appending file
         if (args) |a| {
             const trimmed = std.mem.trim(u8, a, " ");
             if (std.mem.startsWith(u8, trimmed, "-r ")) {
@@ -39,6 +40,12 @@ pub fn executeCommand(
                     try builtins.executeHistoryWrite(stdout, file_path, history.items);
                 }
                 return .continue_loop;
+            } else if (std.mem.startsWith(u8, trimmed, "-a ")) {
+                const file_path = std.mem.trim(u8, trimmed[3..], " ");
+                if (file_path.len > 0) {
+                    try builtins.executeHistoryAppend(stdout, file_path, history.items, last_written_index);
+                }
+                return .continue_loop;
             }
         }