From 379cdbd946dfb035e61f96653db618cba4906864 Mon Sep 17 00:00:00 2001
From: Lucas Faria Mendes <lucas.oliveira1676@etec.sp.gov.br>
Date: Fri, 5 Dec 2025 05:36:01 -0300
Subject: codecrafters submit [skip ci]

---
 src/builtins.zig | 34 ++++++++++++++++++++++++++++++++++
 src/main.zig     |  4 ++--
 src/shell.zig    | 16 ++++++++++++++--
 3 files changed, 50 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/builtins.zig b/src/builtins.zig
index 18e1840..a0d844b 100644
--- a/src/builtins.zig
+++ b/src/builtins.zig
@@ -122,6 +122,15 @@ pub fn executeHistory(stdout: anytype, history_list: []const []const u8, args: ?
     if (args) |a| {
         const trimmed = std.mem.trim(u8, a, " ");
         if (trimmed.len > 0) {
+            // Check if it's a -r flag for reading from file
+            if (std.mem.startsWith(u8, trimmed, "-r ")) {
+                const file_path = std.mem.trim(u8, trimmed[3..], " ");
+                if (file_path.len == 0) {
+                    try stdout.print("history: -r requires a file path\n", .{});
+                }
+                return;
+            }
+
             limit = std.fmt.parseInt(usize, trimmed, 10) catch {
                 try stdout.print("history: invalid argument\n", .{});
                 return;
@@ -134,3 +143,28 @@ pub fn executeHistory(stdout: anytype, history_list: []const []const u8, args: ?
         try stdout.print("    {d}  {s}\n", .{ idx, cmd });
     }
 }
+
+pub fn executeHistoryRead(allocator: std.mem.Allocator, stdout: anytype, file_path: []const u8, history_list: *std.ArrayList([]const u8)) !void {
+    const file = std.fs.cwd().openFile(file_path, .{}) catch {
+        try stdout.print("history: cannot open {s}: error\n", .{file_path});
+        return;
+    };
+    defer file.close();
+
+    const file_size = try file.getEndPos();
+    const buffer = try allocator.alloc(u8, file_size);
+    defer allocator.free(buffer);
+
+    const bytes_read = try file.readAll(buffer);
+    if (bytes_read == 0) return;
+
+    // Parse lines from file
+    var line_iter = std.mem.splitScalar(u8, buffer[0..bytes_read], '\n');
+    while (line_iter.next()) |line| {
+        const trimmed = std.mem.trim(u8, line, " \r");
+        if (trimmed.len > 0) {
+            const line_copy = try allocator.dupe(u8, trimmed);
+            try history_list.append(allocator, line_copy);
+        }
+    }
+}
diff --git a/src/main.zig b/src/main.zig
index 967f13a..69b40e0 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -406,7 +406,7 @@ 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.items);
+                    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);
                     if (result == .exit_shell) break;
                 } else {
                     const result = try shell.executePipeline(allocator, stdout_iface, segments.items);
@@ -415,7 +415,7 @@ 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.items);
+                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);
 
                 if (result == .exit_shell) break;
             }
diff --git a/src/shell.zig b/src/shell.zig
index bd50ff1..fd72288 100644
--- a/src/shell.zig
+++ b/src/shell.zig
@@ -19,12 +19,24 @@ pub fn executeCommand(
     error_redirect: ?[]const u8,
     append_output: ?[]const u8,
     append_error: ?[]const u8,
-    history_list: []const []const u8,
+    history: *std.ArrayList([]const u8),
 ) !builtins.CommandResult {
     if (std.mem.eql(u8, cmd_name, "exit")) return builtins.executeExit();
 
     if (std.mem.eql(u8, cmd_name, "history")) {
-        try builtins.executeHistory(stdout, history_list, args);
+        // Check if args contain -r flag for reading from file
+        if (args) |a| {
+            const trimmed = std.mem.trim(u8, a, " ");
+            if (std.mem.startsWith(u8, trimmed, "-r ")) {
+                const file_path = std.mem.trim(u8, trimmed[3..], " ");
+                if (file_path.len > 0) {
+                    try builtins.executeHistoryRead(allocator, stdout, file_path, history);
+                }
+                return .continue_loop;
+            }
+        }
+
+        try builtins.executeHistory(stdout, history.items, args);
         return .continue_loop;
     }
 
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