From 351649685d4d7751d2fdfe316763d43101e5e173 Mon Sep 17 00:00:00 2001
From: Tim Culverhouse <tim@timculverhouse.com>
Date: Mon, 12 Aug 2024 16:10:17 -0500
Subject: [PATCH] build: add version string and flag

Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
---
 build.zig    | 36 ++++++++++++++++++++++++++++++++++++
 src/main.zig | 22 ++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/build.zig b/build.zig
index 6d34468..05defa4 100644
--- a/build.zig
+++ b/build.zig
@@ -1,5 +1,8 @@
 const std = @import("std");
 
+/// Must be kept in sync with git tags
+const comlink_version: std.SemanticVersion = .{ .major = 0, .minor = 0, .patch = 0 };
+
 pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
@@ -32,6 +35,14 @@ pub fn build(b: *std.Build) void {
         .target = target,
         .optimize = optimize,
     });
+    const opts = b.addOptions();
+    const version_string = version(b) catch |err| {
+        std.debug.print("{}", .{err});
+        @compileError("couldn't get version");
+    };
+    opts.addOption([]const u8, "version", version_string);
+
+    exe.root_module.addOptions("build_options", opts);
     exe.root_module.addImport("tls", tls_dep.module("tls"));
     exe.root_module.addImport("ziglua", ziglua_dep.module("ziglua"));
     exe.root_module.addImport("vaxis", vaxis_dep.module("vaxis"));
@@ -66,3 +77,28 @@ pub fn build(b: *std.Build) void {
     const test_step = b.step("test", "Run unit tests");
     test_step.dependOn(&run_exe_unit_tests.step);
 }
+
+fn version(b: *std.Build) ![]const u8 {
+    if (!std.process.can_spawn) {
+        std.debug.print("error: version info cannot be retrieved from git. Zig version must be provided using -Dversion-string\n", .{});
+        std.process.exit(1);
+    }
+    const version_string = b.fmt("v{d}.{d}.{d}", .{ comlink_version.major, comlink_version.minor, comlink_version.patch });
+
+    var code: u8 = undefined;
+    const git_describe_untrimmed = b.runAllowFail(&[_][]const u8{
+        "git",
+        "-C",
+        b.build_root.path orelse ".",
+        "describe",
+        "--tags",
+        "--abbrev=9",
+    }, &code, .Ignore) catch {
+        return version_string;
+    };
+    if (!std.mem.startsWith(u8, git_describe_untrimmed, version_string)) {
+        std.debug.print("error: tagged version does not match internal version\n", .{});
+        std.process.exit(1);
+    }
+    return std.mem.trim(u8, git_describe_untrimmed, " \n\r");
+}
diff --git a/src/main.zig b/src/main.zig
index 1c84e90..6e3cb0b 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1,4 +1,5 @@
 const std = @import("std");
+const options = @import("build_options");
 const builtin = @import("builtin");
 const comlink = @import("comlink.zig");
 const vaxis = @import("vaxis");
@@ -17,6 +18,8 @@ pub const std_options: std.Options = .{
     },
 };
 
+pub const version = options.version;
+
 /// Called after receiving a terminating signal
 fn cleanUp(sig: c_int) callconv(.C) void {
     if (vaxis.Tty.global_tty) |gty| {
@@ -47,6 +50,15 @@ pub fn main() !void {
     }
     const alloc = gpa.allocator();
 
+    var args = try std.process.argsWithAllocator(alloc);
+    while (args.next()) |arg| {
+        if (argMatch("-v", "--version", arg)) {
+            const stdout = std.io.getStdOut();
+            try stdout.writer().print("comlink {s}\n", .{version});
+            return;
+        }
+    }
+
     // Handle termination signals
     switch (builtin.os.tag) {
         .windows => {},
@@ -89,6 +101,16 @@ pub fn main() !void {
     };
 }
 
+fn argMatch(maybe_short: ?[]const u8, maybe_long: ?[]const u8, arg: [:0]const u8) bool {
+    if (maybe_short) |short| {
+        if (std.mem.eql(u8, short, arg)) return true;
+    }
+    if (maybe_long) |long| {
+        if (std.mem.eql(u8, long, arg)) return true;
+    }
+    return false;
+}
+
 test {
     _ = @import("irc.zig");
 }
-- 
2.51.2