From 354dec925d6089133d1a0632ecdab4bd96d6c8ef Mon Sep 17 00:00:00 2001
From: Matthias Andreas Benkard <code@mail.matthias.benkard.de>
Date: Wed, 13 Aug 2025 19:18:50 +0200
Subject: Add support for external commands.

---
 src/main.zig | 121 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 115 insertions(+), 6 deletions(-)

diff --git a/src/main.zig b/src/main.zig
index 51ebf3c..ef537ea 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -967,14 +967,123 @@ fn executeCommandWithOutput(command: Command, allocator: Allocator, output_captu
         },
         
         .External => |external| {
-            const error_msg = try std.fmt.allocPrint(allocator, "'{s}' is not recognized as an internal or external command,\noperable program or batch file.\n", .{external.program});
-            defer allocator.free(error_msg);
+            // Try to execute external command
+            var child_args = ArrayList([]const u8).init(allocator);
+            defer child_args.deinit();
+            
+            try child_args.append(external.program);
+            for (external.args.items) |arg| {
+                try child_args.append(arg);
+            }
+            
+            var child = std.process.Child.init(child_args.items, allocator);
+            
+            // Set up pipes for capturing output
+            child.stdin_behavior = if (input_source != null) .Pipe else .Inherit;
+            child.stdout_behavior = if (output_capture != null) .Pipe else .Inherit;
+            child.stderr_behavior = if (output_capture != null) .Pipe else .Inherit;
+            
+            const spawn_result = child.spawn();
+            if (spawn_result) |_| {
+                // Spawn succeeded, continue with execution
+            } else |err| switch (err) {
+                error.FileNotFound => {
+                    const error_msg = try std.fmt.allocPrint(allocator, "'{s}' is not recognized as an internal or external command,\noperable program or batch file.\n", .{external.program});
+                    defer allocator.free(error_msg);
+                    
+                    if (output_capture) |capture| {
+                        try capture.write(error_msg);
+                    } else {
+                        print("{s}", .{error_msg});
+                    }
+                    return CommandStatus{ .Code = 1 };
+                },
+                error.AccessDenied => {
+                    const error_msg = "Access is denied.\n";
+                    if (output_capture) |capture| {
+                        try capture.write(error_msg);
+                    } else {
+                        print("{s}", .{error_msg});
+                    }
+                    return CommandStatus{ .Code = 1 };
+                },
+                else => {
+                    const error_msg = try std.fmt.allocPrint(allocator, "Cannot execute '{s}': {}\n", .{ external.program, err });
+                    defer allocator.free(error_msg);
+                    
+                    if (output_capture) |capture| {
+                        try capture.write(error_msg);
+                    } else {
+                        print("{s}", .{error_msg});
+                    }
+                    return CommandStatus{ .Code = 1 };
+                }
+            }
+            
+            // Handle input redirection
+            if (input_source) |source| {
+                if (child.stdin) |stdin| {
+                    const writer = stdin.writer();
+                    
+                    // Reset source position for reading
+                    var temp_source = source.*;
+                    temp_source.position = 0;
+                    
+                    while (try temp_source.readLine(allocator)) |line| {
+                        defer allocator.free(line);
+                        try writer.print("{s}\n", .{line});
+                    }
+                    child.stdin.?.close();
+                    child.stdin = null;
+                }
+            }
+            
+            // Handle output capture
             if (output_capture) |capture| {
-                try capture.write(error_msg);
-            } else {
-                print("{s}", .{error_msg});
+                // Read stdout
+                if (child.stdout) |stdout| {
+                    var buffer: [4096]u8 = undefined;
+                    while (true) {
+                        const bytes_read = stdout.read(&buffer) catch break;
+                        if (bytes_read == 0) break;
+                        try capture.write(buffer[0..bytes_read]);
+                    }
+                }
+                
+                // Read stderr 
+                if (child.stderr) |stderr| {
+                    var buffer: [4096]u8 = undefined;
+                    while (true) {
+                        const bytes_read = stderr.read(&buffer) catch break;
+                        if (bytes_read == 0) break;
+                        try capture.write(buffer[0..bytes_read]);
+                    }
+                }
+            }
+            
+            // Wait for process to complete
+            const term = child.wait() catch |err| {
+                const error_msg = switch (err) {
+                    error.FileNotFound => try std.fmt.allocPrint(allocator, "'{s}' is not recognized as an internal or external command,\noperable program or batch file.\n", .{external.program}),
+                    else => try std.fmt.allocPrint(allocator, "Error waiting for command: {}\n", .{err}),
+                };
+                defer allocator.free(error_msg);
+                
+                if (output_capture) |capture| {
+                    try capture.write(error_msg);
+                } else {
+                    print("{s}", .{error_msg});
+                }
+                return CommandStatus{ .Code = 1 };
+            };
+            
+            // Return exit code
+            switch (term) {
+                .Exited => |code| return CommandStatus{ .Code = @intCast(code) },
+                .Signal => |_| return CommandStatus{ .Code = 1 },
+                .Stopped => |_| return CommandStatus{ .Code = 1 },
+                .Unknown => |_| return CommandStatus{ .Code = 1 },
             }
-            return CommandStatus{ .Code = 1 };
         },
         
         .Redirect => |redirect| {
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