Add 'serve' command for WASM

closes #1

README.md

@@ -12,3 +12,6 @@ And you're ready to go!
 
 Then if you wish to run the app simply execute
 `zig build run` (`zigmod fetch` is no longer required)
+
+In the same way, to build and run the app for WebAssembly, execute
+`zig build serve`

build.zig

@@ -1,6 +1,8 @@
 const std = @import("std");
 const deps = @import("deps.zig");
 
+const PATH_TO_CAPY = ".zigmod/deps/git/github.com/zenith391/capy/";
+
 pub fn build(b: *std.build.Builder) !void {
     // Standard target options allows the person running `zig build` to choose
     // what target to build for. Here we do not override the defaults, which
@@ -12,11 +14,10 @@ pub fn build(b: *std.build.Builder) !void {
     // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
     const mode = b.standardReleaseOptions();
 
-    const exe = b.addExecutable("zgt-template", "src/main.zig");
-    const pathToCapy = ".zigmod/deps/git/github.com/zenith391/capy/";
+    const exe = b.addExecutable("capy-template", "src/main.zig");
     exe.setTarget(target);
     exe.setBuildMode(mode);
-    try deps.imports.capy.install(exe, pathToCapy);
+    try deps.imports.capy.install(exe, PATH_TO_CAPY);
     exe.install();
 
     const run_cmd = exe.run();
@@ -28,6 +29,28 @@ pub fn build(b: *std.build.Builder) !void {
     const run_step = b.step("run", "Run the app");
     run_step.dependOn(&run_cmd.step);
 
+    // Building for WebAssembly
+    // WebAssembly doesn't have a concept of executables, so the way it works is that we make a shared library and capy exports a '_start' function automatically
+    const wasm = b.addSharedLibrary("capy-template", "src/main.zig", .unversioned);
+
+    @setEvalBranchQuota(5000);
+    // Set the target to WebAssembly
+    wasm.setTarget(comptime std.zig.CrossTarget.parse(.{ .arch_os_abi = "wasm32-freestanding" }) catch unreachable);
+    wasm.setBuildMode(mode);
+    wasm.install();
+    try deps.imports.capy.install(wasm, PATH_TO_CAPY);
+
+    if (@import("builtin").zig_backend != .stage2_llvm) {
+        const serve = WebServerStep.create(b, wasm);
+        serve.step.dependOn(&wasm.install_step.?.step);
+        const serve_step = b.step("serve", "Start a web server to run this example");
+        serve_step.dependOn(&serve.step);
+    } else {
+        var step = b.addLog("Please use 'zig build serve -fstage1'", .{});
+        const serve_step = b.step("serve", "Start a web server to run this example");
+        serve_step.dependOn(&step.step);
+    }
+
     const exe_tests = b.addTest("src/main.zig");
     exe_tests.setTarget(target);
     exe_tests.setBuildMode(mode);
@@ -35,3 +58,67 @@ pub fn build(b: *std.build.Builder) !void {
     const test_step = b.step("test", "Run unit tests");
     test_step.dependOn(&exe_tests.step);
 }
+
+const http = deps.imports.apple_pie;
+
+/// Step used for running a web server that can be run with 'zig build serve'
+const WebServerStep = struct {
+    step: std.build.Step,
+    exe: *std.build.LibExeObjStep,
+    builder: *std.build.Builder,
+
+    pub fn create(builder: *std.build.Builder, exe: *std.build.LibExeObjStep) *WebServerStep {
+        const self = builder.allocator.create(WebServerStep) catch unreachable;
+        self.* = .{
+            .step = std.build.Step.init(.custom, "webserver", builder.allocator, WebServerStep.make),
+            .exe = exe,
+            .builder = builder,
+        };
+        return self;
+    }
+
+    const Context = struct {
+        exe: *std.build.LibExeObjStep,
+        builder: *std.build.Builder,
+    };
+
+    pub fn make(step: *std.build.Step) !void {
+        const self = @fieldParentPtr(WebServerStep, "step", step);
+        const allocator = self.builder.allocator;
+
+        var context = Context{ .builder = self.builder, .exe = self.exe };
+        const builder = http.router.Builder(*Context);
+        std.debug.print("Web server opened at http://localhost:8080/\n", .{});
+        try http.listenAndServe(
+            allocator,
+            try std.net.Address.parseIp("127.0.0.1", 8080),
+            &context,
+            comptime http.router.Router(*Context, &.{
+                builder.get("/", index),
+                builder.get("/zig-app.wasm", wasmFile),
+            }),
+        );
+    }
+
+    fn index(context: *Context, response: *http.Response, request: http.Request) !void {
+        const allocator = request.arena;
+        const buildRoot = context.builder.build_root;
+        const file = try std.fs.cwd().openFile(try std.fs.path.join(allocator, &.{ buildRoot, PATH_TO_CAPY ++ "src/backends/wasm/page.html" }), .{});
+        defer file.close();
+        const text = try file.readToEndAlloc(allocator, std.math.maxInt(usize));
+
+        try response.headers.put("Content-Type", "text/html");
+        try response.writer().writeAll(text);
+    }
+
+    fn wasmFile(context: *Context, response: *http.Response, request: http.Request) !void {
+        const allocator = request.arena;
+        const path = context.exe.getOutputSource().getPath(context.builder);
+        const file = try std.fs.cwd().openFile(path, .{});
+        defer file.close();
+        const text = try file.readToEndAlloc(allocator, std.math.maxInt(usize));
+
+        try response.headers.put("Content-Type", "application/wasm");
+        try response.writer().writeAll(text);
+    }
+};

zigmod.lock

@@ -1,2 +1,3 @@
 2
-git https://github.com/zenith391/zgt commit-80238123d9cab0ec83680a4958b8ed7ae1fcf1fd
+git https://github.com/zenith391/capy commit-2e31fde7e328599352eb01f8894acd53389d0ec0
+git https://github.com/Luukdegram/apple_pie commit-54444805f41cc958d55940bc8931cd3cf1979d8c

zigmod.yml

@@ -1,7 +1,8 @@
 id: eje8wf3r4lz8em2jnign4ocxywosgkrk1dr6lgcbb0y1ne6y
-name: zgt-template
+name: capy-template
 license: Unlicense
 description: Simple template for Capy apps
 build_dependencies:
     - src: git https://github.com/zenith391/capy
+    - src: git https://github.com/Luukdegram/apple_pie # this is only necessary if you want 'zig build serve'
 root_depedencies: