feat: invalid page for unavailable resources

Accessing resources which are not available, the invalid page will be
rendered instead. The original attempt for access will be logged.

src/content.zig

@@ -57,10 +57,16 @@ pub fn Content(App: type) type {
                 },
                 .blog => |path| {
                     model.page.deinit(this.allocator);
+                    model.document.deinit(this.allocator);
+                    errdefer {
+                        if (path) |p| this.allocator.free(p);
+                        model.document = .invalidPage;
+                        model.page = .{ .blog = null };
+                    }
+
+                    model.document = .init(try std.fs.cwd().readFileAlloc(if (path) |p| p else "./doc/blog.md", this.allocator, .unlimited));
                     model.page = .{ .blog = path };
 
-                    model.document.deinit(this.allocator);
-                    model.document = .init(try std.fs.cwd().readFileAlloc(if (path) |p| p else "./doc/blog.md", this.allocator, .unlimited));
                     this.document = &model.document;
                 },
                 else => {},

src/main.zig

@@ -1,4 +1,11 @@
-// usage: tui_website <path>
+// TODO
+// - should the path containing the contents of the tui-website reside in the
+//   hardcode `./doc` directory or shall this become a compilation argument to
+//   allow for custom directory locations?
+
+// usage: tui_website <location>
+// <location>: partial path to the document without the file extension and the beginning `./doc` path
+//             ending `/` (as used from the web-world) are trimmed automatically
 pub fn main() !void {
     errdefer |err| log.err("Application Error: {any}", .{err});
 
@@ -106,7 +113,11 @@ pub fn main() !void {
         //   -> enforce a specific structure?
         // -> in case an invalid path is provided the 404 error page shall be shown
         // -> reporte an corresponding error! (such that I can see that in the log)
-        app.postEvent(.{ .blog = try allocator.dupe(u8, path) });
+        var blog = path[0..path.len];
+        blog = std.mem.trimStart(u8, blog, "./");
+        blog = std.mem.trimEnd(u8, blog, ".md");
+        blog = std.mem.trimEnd(u8, blog, "/");
+        app.postEvent(.{ .blog = try std.fmt.allocPrint(allocator, "./doc/{s}.md", .{blog}) });
     }
     arg_it.deinit();
 
@@ -127,10 +138,12 @@ pub fn main() !void {
             // pre event handling
             switch (event) {
                 .key => |key| {
-                    if (key.eql(.{ .cp = 'c', .mod = .{ .ctrl = true } })) app.quit();
+                    if (key.eql(.{ .cp = 'c', .mod = .{ .ctrl = true } }) or key.eql(.{ .cp = 'q' })) app.quit();
                     // test if the event handling is working correctly
                     if (key.eql(.{ .cp = zterm.input.Space })) app.postEvent(.{ .blog = allocator.dupe(u8, "./doc/test.md") catch unreachable });
                 },
+                .about => log.info(ResourceRequestFormat, .{"./doc/about.md"}),
+                .blog => |path| log.info(ResourceRequestFormat, .{if (path) |p| p else "./doc/blog.md"}),
                 .err => |err| log.err("Received {s} with message: {s}", .{ @errorName(err.err), err.msg }),
                 else => {},
             }
@@ -161,6 +174,8 @@ pub const panic = App.panic_handler;
 pub const std_options = zlog.std_options;
 const log = std.log.scoped(.default);
 
+const ResourceRequestFormat = "Requesting resource: `{s}`";
+
 const std = @import("std");
 const assert = std.debug.assert;
 const zlog = @import("zlog");

src/model.zig

@@ -33,6 +33,12 @@ pub const Document = struct {
         date,
     };
 
+    pub const invalidPage: @This() = .{
+        .title = "Page not found",
+        .content = "Requested page does not exist",
+        .ptr = undefined,
+    };
+
     pub fn init(content: []const u8) @This() {
         if (std.mem.startsWith(u8, content, "---\n")) {
             var document: @This() = .{ .ptr = content };