Merge pull request #1338 from mitchellh/help-rebase

Add `--help` to the Ghostty CLI

9 files changed, 372 insertions, 2 deletions

diff --git a/src/cli/action.zig b/src/cli/action.zig
index f97a5d2cf..2e3afb1c0 100644
--- a/src/cli/action.zig
+++ b/src/cli/action.zig
@@ -1,7 +1,9 @@
 const std = @import("std");
 const Allocator = std.mem.Allocator;
+const help_strings = @import("help_strings");
 
 const list_fonts = @import("list_fonts.zig");
+const help = @import("help.zig");
 const version = @import("version.zig");
 const list_keybinds = @import("list_keybinds.zig");
 const list_themes = @import("list_themes.zig");
@@ -14,6 +16,9 @@ pub const Action = enum {
     /// Output the version and exit
     version,
 
+    /// Output help information for the CLI or configuration
+    help,
+
     /// List available fonts
     @"list-fonts",
 
@@ -35,6 +40,9 @@ pub const Action = enum {
         InvalidAction,
     };
 
+    /// This should be returned by actions that want to print the help text.
+    pub const help_error = error.ActionHelpRequested;
+
     /// Detect the action from CLI args.
     pub fn detectCLI(alloc: Allocator) !?Action {
         var iter = try std.process.argsWithAllocator(alloc);
@@ -44,31 +52,90 @@ pub const Action = enum {
 
     /// Detect the action from any iterator, used primarily for tests.
     pub fn detectIter(iter: anytype) Error!?Action {
+        var pending_help: bool = false;
         var pending: ?Action = null;
         while (iter.next()) |arg| {
             // Special case, --version always outputs the version no
             // matter what, no matter what other args exist.
             if (std.mem.eql(u8, arg, "--version")) return .version;
 
+            // --help matches "help" but if a subcommand is specified
+            // then we match the subcommand.
+            if (std.mem.eql(u8, arg, "--help") or std.mem.eql(u8, arg, "-h")) {
+                pending_help = true;
+                continue;
+            }
+
             // Commands must start with "+"
             if (arg.len == 0 or arg[0] != '+') continue;
             if (pending != null) return Error.MultipleActions;
             pending = std.meta.stringToEnum(Action, arg[1..]) orelse return Error.InvalidAction;
         }
 
+        // If we have an action, we always return that action, even if we've
+        // seen "--help" or "-h" because the action may have its own help text.
+        if (pending != null) return pending;
+
+        // If we've seen "--help" or "-h" then we return the help action.
+        if (pending_help) return .help;
+
         return pending;
     }
 
     /// Run the action. This returns the exit code to exit with.
     pub fn run(self: Action, alloc: Allocator) !u8 {
+        return self.runMain(alloc) catch |err| switch (err) {
+            // If help is requested, then we use some comptime trickery
+            // to find this action in the help strings and output that.
+            help_error => err: {
+                inline for (@typeInfo(Action).Enum.fields) |field| {
+                    // Future note: for now we just output the help text directly
+                    // to stdout. In the future we can style this much prettier
+                    // for all commands by just changing this one place.
+
+                    if (std.mem.eql(u8, field.name, @tagName(self))) {
+                        const stdout = std.io.getStdOut().writer();
+                        const text = @field(help_strings.Action, field.name) ++ "\n";
+                        stdout.writeAll(text) catch |write_err| {
+                            std.log.warn("failed to write help text: {}\n", .{write_err});
+                            break :err 1;
+                        };
+
+                        break :err 0;
+                    }
+                }
+
+                break :err err;
+            },
+            else => err,
+        };
+    }
+
+    fn runMain(self: Action, alloc: Allocator) !u8 {
         return switch (self) {
-            .version => try version.run(),
+            .version => try version.run(alloc),
+            .help => try help.run(alloc),
             .@"list-fonts" => try list_fonts.run(alloc),
             .@"list-keybinds" => try list_keybinds.run(alloc),
             .@"list-themes" => try list_themes.run(alloc),
             .@"list-colors" => try list_colors.run(alloc),
         };
     }
+
+    /// Returns the filename associated with an action. This is a relative
+    /// path from the root src/ directory.
+    pub fn file(comptime self: Action) []const u8 {
+        comptime {
+            const filename = filename: {
+                const tag = @tagName(self);
+                var filename: [tag.len]u8 = undefined;
+                _ = std.mem.replace(u8, tag, "-", "_", &filename);
+                break :filename &filename;
+            };
+
+            return "cli/" ++ filename ++ ".zig";
+        }
+    }
 };
 
 test "parse action none" {
diff --git a/src/cli/args.zig b/src/cli/args.zig
index c226493f9..773457cf8 100644
--- a/src/cli/args.zig
+++ b/src/cli/args.zig
@@ -77,6 +77,17 @@ pub fn parse(comptime T: type, alloc: Allocator, dst: *T, iter: anytype) !void {
             if (!try dst.parseManuallyHook(arena_alloc, arg, iter)) return;
         }
 
+        // If the destination supports help then we check for it, call
+        // the help function and return.
+        if (@hasDecl(T, "help")) {
+            if (mem.eql(u8, arg, "--help") or
+                mem.eql(u8, arg, "-h"))
+            {
+                try dst.help();
+                return;
+            }
+        }
+
         if (mem.startsWith(u8, arg, "--")) {
             var key: []const u8 = arg[2..];
             const value: ?[]const u8 = value: {
diff --git a/src/cli/help.zig b/src/cli/help.zig
new file mode 100644
index 000000000..e75b1b617
--- /dev/null
+++ b/src/cli/help.zig
@@ -0,0 +1,71 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const args = @import("args.zig");
+const Action = @import("action.zig").Action;
+
+// Note that this options struct doesn't implement the `help` decl like
+// other actions. That is because the help command is special and wants to
+// handle its own logic around help detection.
+pub const Options = struct {
+    /// This must be registered so that it isn't an error to pass `--help`
+    help: bool = false,
+
+    pub fn deinit(self: Options) void {
+        _ = self;
+    }
+};
+
+/// The `help` command shows general help about Ghostty. You can also
+/// specify `--help` or `-h` along with any action such as `+list-themes`
+/// to see help for a specific action.
+pub fn run(alloc: Allocator) !u8 {
+    var opts: Options = .{};
+    defer opts.deinit();
+
+    {
+        var iter = try std.process.argsWithAllocator(alloc);
+        defer iter.deinit();
+        try args.parse(Options, alloc, &opts, &iter);
+    }
+
+    const stdout = std.io.getStdOut().writer();
+    try stdout.writeAll(
+        \\Usage: ghostty [+action] [options]
+        \\
+        \\Run the Ghostty terminal emulator or a specific helper action.
+        \\
+        \\If no `+action` is specified, run the Ghostty terminal emulator.
+        \\All configuration keys are available as command line options.
+        \\To specify a configuration key, use the `--<key>=<value>` syntax
+        \\where key and value are the same format you'd put into a configuration
+        \\file. For example, `--font-size=12` or `--font-family="Fira Code"`.
+        \\
+        \\To see a list of all available configuration options, please see
+        \\the `src/config/Config.zig` file. A future update will allow seeing
+        \\the list of configuration options from the command line.
+        \\
+        \\A special command line argument `-e <command>` can be used to run
+        \\the specific command inside the terminal emulator. For example,
+        \\`ghostty -e top` will run the `top` command inside the terminal.
+        \\
+        \\On macOS, launching the terminal emulator from the CLI is not
+        \\supported and only actions are supported.
+        \\
+        \\Available actions:
+        \\
+        \\
+    );
+
+    inline for (@typeInfo(Action).Enum.fields) |field| {
+        try stdout.print("  +{s}\n", .{field.name});
+    }
+
+    try stdout.writeAll(
+        \\
+        \\Specify `+<action> --help` to see the help for a specific action,
+        \\where `<action>` is one of actions listed below.
+        \\
+    );
+
+    return 0;
+}
diff --git a/src/cli/list_colors.zig b/src/cli/list_colors.zig
index 2b6dd1d0e..447f70552 100644
--- a/src/cli/list_colors.zig
+++ b/src/cli/list_colors.zig
@@ -1,4 +1,5 @@
 const std = @import("std");
+const Action = @import("action.zig").Action;
 const args = @import("args.zig");
 const x11_color = @import("../terminal/main.zig").x11_color;
 
@@ -6,6 +7,12 @@ pub const Options = struct {
     pub fn deinit(self: Options) void {
         _ = self;
     }
+
+    /// Enables "-h" and "--help" to work.
+    pub fn help(self: Options) !void {
+        _ = self;
+        return Action.help_error;
+    }
 };
 
 /// The "list-colors" command is used to list all the named RGB colors in
diff --git a/src/cli/list_fonts.zig b/src/cli/list_fonts.zig
index 0e48bf0f9..b49e43a30 100644
--- a/src/cli/list_fonts.zig
+++ b/src/cli/list_fonts.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
+const Action = @import("action.zig").Action;
 const args = @import("args.zig");
 const font = @import("../font/main.zig");
 
@@ -26,6 +27,12 @@ pub const Config = struct {
         if (self._arena) |arena| arena.deinit();
         self.* = undefined;
     }
+
+    /// Enables "-h" and "--help" to work.
+    pub fn help(self: Config) !void {
+        _ = self;
+        return Action.help_error;
+    }
 };
 
 /// The list-fonts command is used to list all the available fonts for Ghostty.
diff --git a/src/cli/list_keybinds.zig b/src/cli/list_keybinds.zig
index 8d9585be9..15df1815e 100644
--- a/src/cli/list_keybinds.zig
+++ b/src/cli/list_keybinds.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 const inputpkg = @import("../input.zig");
 const args = @import("args.zig");
+const Action = @import("action.zig").Action;
 const Arena = std.heap.ArenaAllocator;
 const Allocator = std.mem.Allocator;
 const Config = @import("../config/Config.zig");
@@ -13,6 +14,12 @@ pub const Options = struct {
     pub fn deinit(self: Options) void {
         _ = self;
     }
+
+    /// Enables "-h" and "--help" to work.
+    pub fn help(self: Options) !void {
+        _ = self;
+        return Action.help_error;
+    }
 };
 
 /// The "list-keybinds" command is used to list all the available keybinds
diff --git a/src/cli/list_themes.zig b/src/cli/list_themes.zig
index be3a41c14..98c3859c6 100644
--- a/src/cli/list_themes.zig
+++ b/src/cli/list_themes.zig
@@ -1,6 +1,7 @@
 const std = @import("std");
 const inputpkg = @import("../input.zig");
 const args = @import("args.zig");
+const Action = @import("action.zig").Action;
 const Arena = std.heap.ArenaAllocator;
 const Allocator = std.mem.Allocator;
 const Config = @import("../config/Config.zig");
@@ -10,6 +11,12 @@ pub const Options = struct {
     pub fn deinit(self: Options) void {
         _ = self;
     }
+
+    /// Enables "-h" and "--help" to work.
+    pub fn help(self: Options) !void {
+        _ = self;
+        return Action.help_error;
+    }
 };
 
 /// The "list-themes" command is used to list all the available themes
diff --git a/src/cli/version.zig b/src/cli/version.zig
index b3395f4cd..fb12faa2e 100644
--- a/src/cli/version.zig
+++ b/src/cli/version.zig
@@ -1,10 +1,36 @@
 const std = @import("std");
+const Allocator = std.mem.Allocator;
 const builtin = @import("builtin");
 const build_config = @import("../build_config.zig");
 const xev = @import("xev");
 const renderer = @import("../renderer.zig");
+const args = @import("args.zig");
+const Action = @import("action.zig").Action;
+
+pub const Options = struct {
+    pub fn deinit(self: Options) void {
+        _ = self;
+    }
+
+    /// Enables "-h" and "--help" to work.
+    pub fn help(self: Options) !void {
+        _ = self;
+        return Action.help_error;
+    }
+};
+
+/// The `version` command is used to display information
+/// about Ghostty.
+pub fn run(alloc: Allocator) !u8 {
+    var opts: Options = .{};
+    defer opts.deinit();
+
+    {
+        var iter = try std.process.argsWithAllocator(alloc);
+        defer iter.deinit();
+        try args.parse(Options, alloc, &opts, &iter);
+    }
 
-pub fn run() !u8 {
     const stdout = std.io.getStdOut().writer();
     try stdout.print("Ghostty {s}\n\n", .{build_config.version_string});
     try stdout.print("Build Config\n", .{});
diff --git a/src/helpgen.zig b/src/helpgen.zig
new file mode 100644
index 000000000..4447346f4
--- /dev/null
+++ b/src/helpgen.zig
@@ -0,0 +1,167 @@
+//! This program is used to generate the help strings from the configuration
+//! file and CLI actions for Ghostty. These can then be used to generate
+//! help, docs, website, etc.
+
+const std = @import("std");
+const ziglyph = @import("ziglyph");
+const Config = @import("config/Config.zig");
+const Action = @import("cli/action.zig").Action;
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    const alloc = gpa.allocator();
+
+    const stdout = std.io.getStdOut().writer();
+    try stdout.writeAll(
+        \\// THIS FILE IS AUTO GENERATED
+        \\
+        \\
+    );
+
+    try genConfig(alloc, stdout);
+    try genActions(alloc, stdout);
+}
+
+fn genConfig(alloc: std.mem.Allocator, writer: anytype) !void {
+    var ast = try std.zig.Ast.parse(alloc, @embedFile("config/Config.zig"), .zig);
+    defer ast.deinit(alloc);
+
+    try writer.writeAll(
+        \\/// Configuration help
+        \\pub const Config = struct {
+        \\
+        \\
+    );
+
+    inline for (@typeInfo(Config).Struct.fields) |field| {
+        if (field.name[0] == '_') continue;
+        try genConfigField(alloc, writer, ast, field.name);
+    }
+
+    try writer.writeAll("};\n");
+}
+
+fn genConfigField(
+    alloc: std.mem.Allocator,
+    writer: anytype,
+    ast: std.zig.Ast,
+    comptime field: []const u8,
+) !void {
+    const tokens = ast.tokens.items(.tag);
+    for (tokens, 0..) |token, i| {
+        // We only care about identifiers that are preceded by doc comments.
+        if (token != .identifier) continue;
+        if (tokens[i - 1] != .doc_comment) continue;
+
+        // Identifier may have @"" so we strip that.
+        const name = ast.tokenSlice(@intCast(i));
+        const key = if (name[0] == '@') name[2 .. name.len - 1] else name;
+        if (!std.mem.eql(u8, key, field)) continue;
+
+        const comment = try extractDocComments(alloc, ast, @intCast(i - 1), tokens);
+        try writer.writeAll("pub const ");
+        try writer.writeAll(name);
+        try writer.writeAll(": [:0]const u8 = \n");
+        try writer.writeAll(comment);
+        try writer.writeAll("\n");
+        break;
+    }
+}
+
+fn genActions(alloc: std.mem.Allocator, writer: anytype) !void {
+    try writer.writeAll(
+        \\
+        \\/// Actions help
+        \\pub const Action = struct {
+        \\
+        \\
+    );
+
+    inline for (@typeInfo(Action).Enum.fields) |field| {
+        const action_file = comptime action_file: {
+            const action = @field(Action, field.name);
+            break :action_file action.file();
+        };
+
+        var ast = try std.zig.Ast.parse(alloc, @embedFile(action_file), .zig);
+        defer ast.deinit(alloc);
+        const tokens: []std.zig.Token.Tag = ast.tokens.items(.tag);
+
+        for (tokens, 0..) |token, i| {
+            // We're looking for a function named "run".
+            if (token != .keyword_fn) continue;
+            if (!std.mem.eql(u8, ast.tokenSlice(@intCast(i + 1)), "run")) continue;
+
+            // The function must be preceded by a doc comment.
+            if (tokens[i - 2] != .doc_comment) {
+                std.debug.print(
+                    "doc comment must be present on run function of the {s} action!",
+                    .{field.name},
+                );
+                std.process.exit(1);
+            }
+
+            const comment = try extractDocComments(alloc, ast, @intCast(i - 2), tokens);
+            try writer.writeAll("pub const @\"");
+            try writer.writeAll(field.name);
+            try writer.writeAll("\" = \n");
+            try writer.writeAll(comment);
+            try writer.writeAll("\n\n");
+            break;
+        }
+    }
+
+    try writer.writeAll("};\n");
+}
+
+fn extractDocComments(
+    alloc: std.mem.Allocator,
+    ast: std.zig.Ast,
+    index: std.zig.Ast.TokenIndex,
+    tokens: []std.zig.Token.Tag,
+) ![]const u8 {
+    // Find the first index of the doc comments. The doc comments are
+    // always stacked on top of each other so we can just go backwards.
+    const start_idx: usize = start_idx: for (0..index) |i| {
+        const reverse_i = index - i - 1;
+        const token = tokens[reverse_i];
+        if (token != .doc_comment) break :start_idx reverse_i + 1;
+    } else unreachable;
+
+    // Go through and build up the lines.
+    var lines = std.ArrayList([]const u8).init(alloc);
+    defer lines.deinit();
+    for (start_idx..index + 1) |i| {
+        const token = tokens[i];
+        if (token != .doc_comment) break;
+        try lines.append(ast.tokenSlice(@intCast(i))[3..]);
+    }
+
+    // Convert the lines to a multiline string.
+    var buffer = std.ArrayList(u8).init(alloc);
+    const writer = buffer.writer();
+    const prefix = findCommonPrefix(lines);
+    for (lines.items) |line| {
+        try writer.writeAll("    \\\\");
+        try writer.writeAll(line[@min(prefix, line.len)..]);
+        try writer.writeAll("\n");
+    }
+    try writer.writeAll(";\n");
+
+    return buffer.toOwnedSlice();
+}
+
+fn findCommonPrefix(lines: std.ArrayList([]const u8)) usize {
+    var m: usize = std.math.maxInt(usize);
+    for (lines.items) |line| {
+        var n: usize = std.math.maxInt(usize);
+        for (line, 0..) |c, i| {
+            if (c != ' ') {
+                n = i;
+                break;
+            }
+        }
+        m = @min(m, n);
+    }
+    return m;
+}