From eed6979868573df6786406c568204bf02d01a27d Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Thu, 16 Feb 2023 08:52:40 -0800
Subject: [PATCH] apprt: start embedded implement, make App API available to C

---
 include/ghostty.h      | 21 +++++++++++++++++++++
 src/App.zig            | 40 +++++++++++++++++++++++++++++++++++++--
 src/DevMode.zig        |  4 +++-
 src/apprt.zig          | 10 ++++++----
 src/apprt/embedded.zig | 43 ++++++++++++++++++++++++++++++++++++++++++
 src/apprt/glfw.zig     |  4 +++-
 src/build_config.zig   | 11 +++++++++--
 src/main.zig           |  2 +-
 src/main_c.zig         |  7 +++++++
 9 files changed, 131 insertions(+), 11 deletions(-)
 create mode 100644 src/apprt/embedded.zig

diff --git a/include/ghostty.h b/include/ghostty.h
index ea8df672d..a256b7364 100644
--- a/include/ghostty.h
+++ b/include/ghostty.h
@@ -16,14 +16,35 @@ extern "C" {
 
 #define GHOSTTY_SUCCESS 0
 
+//-------------------------------------------------------------------
+// Types
+
+// Fully defined types. This MUST be kept in sync with equivalent Zig
+// structs. To find the Zig struct, grep for this type name. The documentation
+// for all of these types is available in the Zig source.
+typedef void (*ghostty_runtime_wakeup_cb)(void *);
+typedef struct {
+    void *userdata;
+    ghostty_runtime_wakeup_cb wakeup_cb;
+} ghostty_runtime_config_s;
+
+// Opaque types
+typedef void *ghostty_app_t;
 typedef void *ghostty_config_t;
 
+//-------------------------------------------------------------------
+// Published API
+
 int ghostty_init(void);
+
 ghostty_config_t ghostty_config_new();
 void ghostty_config_free(ghostty_config_t);
 void ghostty_config_load_string(ghostty_config_t, const char *, uintptr_t);
 void ghostty_config_finalize(ghostty_config_t);
 
+ghostty_app_t ghostty_app_new(ghostty_runtime_config_s *, ghostty_config_t);
+void ghostty_app_free(ghostty_app_t);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/App.zig b/src/App.zig
index 78fccbdec..731a6ee6b 100644
--- a/src/App.zig
+++ b/src/App.zig
@@ -65,9 +65,13 @@ pub const Darwin = struct {
 /// Initialize the main app instance. This creates the main window, sets
 /// up the renderer state, compiles the shaders, etc. This is the primary
 /// "startup" logic.
-pub fn create(alloc: Allocator, config: *const Config) !*App {
+pub fn create(
+    alloc: Allocator,
+    rt_opts: apprt.runtime.App.Options,
+    config: *const Config,
+) !*App {
     // Initialize app runtime
-    var app_backend = try apprt.runtime.App.init();
+    var app_backend = try apprt.runtime.App.init(rt_opts);
     errdefer app_backend.terminate();
 
     // The mailbox for messaging this thread
@@ -303,3 +307,35 @@ pub const Wasm = if (!builtin.target.isWasm()) struct {} else struct {
     //     }
     // }
 };
+
+// C API
+pub const CAPI = struct {
+    const global = &@import("main.zig").state;
+
+    /// Create a new app.
+    export fn ghostty_app_new(
+        opts: *const apprt.runtime.App.Options,
+        config: *const Config,
+    ) ?*App {
+        return app_new_(opts, config) catch |err| {
+            log.err("error initializing app err={}", .{err});
+            return null;
+        };
+    }
+
+    fn app_new_(
+        opts: *const apprt.runtime.App.Options,
+        config: *const Config,
+    ) !*App {
+        const app = try App.create(global.alloc, opts.*, config);
+        errdefer app.destroy();
+        return app;
+    }
+
+    export fn ghostty_app_free(ptr: ?*App) void {
+        if (ptr) |v| {
+            v.destroy();
+            v.alloc.destroy(v);
+        }
+    }
+};
diff --git a/src/DevMode.zig b/src/DevMode.zig
index 2df187b82..2b037ce2a 100644
--- a/src/DevMode.zig
+++ b/src/DevMode.zig
@@ -4,6 +4,7 @@ const DevMode = @This();
 
 const std = @import("std");
 const builtin = @import("builtin");
+const build_config = @import("build_config.zig");
 const imgui = @import("imgui");
 const Allocator = std.mem.Allocator;
 const assert = std.debug.assert;
@@ -15,7 +16,8 @@ const Config = @import("config.zig").Config;
 
 /// If this is false, the rest of the terminal will be compiled without
 /// dev mode support at all.
-pub const enabled = !builtin.target.isWasm();
+/// TODO: remove this and use build_config everywhere
+pub const enabled = build_config.devmode_enabled;
 
 /// The global DevMode instance that can be used app-wide. Assume all functions
 /// are NOT thread-safe unless otherwise noted.
diff --git a/src/apprt.zig b/src/apprt.zig
index 4246d5a3c..36e2a2571 100644
--- a/src/apprt.zig
+++ b/src/apprt.zig
@@ -9,20 +9,22 @@
 //! logic as possible, and to only reach out to platform-specific implementation
 //! code when absolutely necessary.
 const builtin = @import("builtin");
+const build_config = @import("build_config.zig");
 
 pub usingnamespace @import("apprt/structs.zig");
 pub const glfw = @import("apprt/glfw.zig");
 pub const browser = @import("apprt/browser.zig");
+pub const embedded = @import("apprt/embedded.zig");
 pub const Window = @import("apprt/Window.zig");
 
 /// The implementation to use for the app runtime. This is comptime chosen
 /// so that every build has exactly one application runtime implementation.
 /// Note: it is very rare to use Runtime directly; most usage will use
 /// Window or something.
-pub const runtime = if (builtin.target.isWasm())
-    browser
-else switch (builtin.os.tag) {
-    else => glfw,
+pub const runtime = switch (build_config.artifact) {
+    .exe => glfw,
+    .lib => embedded,
+    .wasm_module => browser,
 };
 
 test {
diff --git a/src/apprt/embedded.zig b/src/apprt/embedded.zig
new file mode 100644
index 000000000..fa61e85e5
--- /dev/null
+++ b/src/apprt/embedded.zig
@@ -0,0 +1,43 @@
+//! Application runtime for the embedded version of Ghostty. The embedded
+//! version is when Ghostty is embedded within a parent host application,
+//! rather than owning the application lifecycle itself. This is used for
+//! example for the macOS build of Ghostty so that we can use a native
+//! Swift+XCode-based application.
+
+pub const App = struct {
+    /// Because we only expect the embedding API to be used in embedded
+    /// environments, the options are extern so that we can expose it
+    /// directly to a C callconv and not pay for any translation costs.
+    ///
+    /// C type: ghostty_runtime_config_s
+    pub const Options = extern struct {
+        /// Userdata that is passed to all the callbacks.
+        userdata: ?*anyopaque = null,
+
+        /// Callback called to wakeup the event loop. This should trigger
+        /// a full tick of the app loop.
+        wakeup: *const fn (?*anyopaque) callconv(.C) void,
+    };
+
+    pub fn init(_: Options) !App {
+        return .{};
+    }
+
+    pub fn terminate(self: App) void {
+        _ = self;
+    }
+
+    pub fn wakeup(self: App) !void {
+        _ = self;
+    }
+
+    pub fn wait(self: App) !void {
+        _ = self;
+    }
+};
+
+pub const Window = struct {
+    pub fn deinit(self: *Window) void {
+        _ = self;
+    }
+};
diff --git a/src/apprt/glfw.zig b/src/apprt/glfw.zig
index 0cb5fab8e..f64ad200d 100644
--- a/src/apprt/glfw.zig
+++ b/src/apprt/glfw.zig
@@ -26,7 +26,9 @@ const glfwNative = glfw.Native(.{
 const log = std.log.scoped(.glfw);
 
 pub const App = struct {
-    pub fn init() !App {
+    pub const Options = struct {};
+
+    pub fn init(_: Options) !App {
         if (!glfw.init(.{})) return error.GlfwInitFailed;
         return .{};
     }
diff --git a/src/build_config.zig b/src/build_config.zig
index 1d1f538e9..2baaa48b8 100644
--- a/src/build_config.zig
+++ b/src/build_config.zig
@@ -10,6 +10,10 @@ const assert = std.debug.assert;
 /// building a standalone exe, an embedded lib, etc.
 pub const artifact = Artifact.detect();
 
+/// Whether our devmode UI is enabled or not. This requires imgui to be
+/// compiled.
+pub const devmode_enabled = artifact == .exe;
+
 pub const Artifact = enum {
     /// Standalone executable
     exe,
@@ -29,8 +33,11 @@ pub const Artifact = enum {
 
         return switch (builtin.output_mode) {
             .Exe => .exe,
-            .Obj => .lib,
-            else => unreachable,
+            .Lib => .lib,
+            else => {
+                @compileLog(builtin.output_mode);
+                @compileError("unsupported artifact output mode");
+            },
         };
     }
 };
diff --git a/src/main.zig b/src/main.zig
index 24f0b76d5..8ad3186bf 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -92,7 +92,7 @@ pub fn main() !void {
     glfw.setErrorCallback(glfwErrorCallback);
 
     // Run our app with a single initial window to start.
-    var app = try App.create(alloc, &config);
+    var app = try App.create(alloc, .{}, &config);
     defer app.destroy();
     try app.run();
 }
diff --git a/src/main_c.zig b/src/main_c.zig
index a6823260b..344d477bb 100644
--- a/src/main_c.zig
+++ b/src/main_c.zig
@@ -11,10 +11,17 @@ const assert = std.debug.assert;
 const builtin = @import("builtin");
 const main = @import("main.zig");
 
+// Some comptime assertions that our C API depends on.
+comptime {
+    const apprt = @import("apprt.zig");
+    assert(apprt.runtime == apprt.embedded);
+}
+
 /// Global options so we can log. This is identical to main.
 pub const std_options = main.std_options;
 
 pub usingnamespace @import("config.zig").CAPI;
+pub usingnamespace @import("App.zig").CAPI;
 
 /// Initialize ghostty global state. It is possible to have more than
 /// one global state but it has zero practical benefit.