feat(content): routing to provided .blog paths

This is a starting point to dynamically loading `markdown` files as blog
entries. With this change the *doc/about.md* and *doc/blog.md* files
are no longer builded into the executable and instead read from the
filesystem during runtime (along with the new test file *doc/test.md*).

src/content.zig

@@ -1,11 +1,12 @@
 pub fn Content(App: type) type {
     return struct {
-        page: App.Model.Pages,
+        allocator: Allocator,
+        document: *const App.Model.Document,
 
         pub fn init(allocator: Allocator) @This() {
-            _ = allocator;
             return .{
-                .page = .blog,
+                .allocator = allocator,
+                .document = undefined,
             };
         }
 
@@ -22,10 +23,7 @@ pub fn Content(App: type) type {
 
         fn minSize(ctx: *anyopaque, size: zterm.Point) zterm.Point {
             const this: *const @This() = @ptrCast(@alignCast(ctx));
-            const text = switch (this.page) {
-                .about => @embedFile("about"),
-                .blog => @embedFile("blog"),
-            };
+            const text = this.document.content;
             var index: usize = 0;
             var new_size: zterm.Point = .{ .x = size.x };
 
@@ -48,17 +46,25 @@ pub fn Content(App: type) type {
         fn handle(ctx: *anyopaque, model: *App.Model, event: App.Event) !void {
             const this: *@This() = @ptrCast(@alignCast(ctx));
             switch (event) {
+                .init => this.document = &model.document,
                 .about => {
+                    model.page.deinit(this.allocator);
                     model.page = .about;
-                    model.document = .init(@embedFile("about"));
+
+                    model.document.deinit(this.allocator);
+                    model.document = .init(try std.fs.cwd().readFileAlloc("./doc/about.md", this.allocator, .unlimited));
+                    this.document = &model.document;
                 },
-                .blog => {
-                    model.page = .blog;
-                    model.document = .init(@embedFile("blog"));
+                .blog => |path| {
+                    model.page.deinit(this.allocator);
+                    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 => {},
             }
-            this.page = model.page;
         }
 
         fn content(ctx: *anyopaque, model: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
@@ -88,10 +94,6 @@ pub fn Content(App: type) type {
 
 pub fn Title(App: type) type {
     return struct {
-        pub fn init() @This() {
-            return .{};
-        }
-
         pub fn element(this: *@This()) App.Element {
             return .{
                 .ptr = this,
@@ -122,15 +124,8 @@ pub fn Title(App: type) type {
 
 pub fn InfoBanner(App: type) type {
     return struct {
-        left_text: []const u8,
-        right_text: []const u8,
-
-        pub fn init() @This() {
-            return .{
-                .left_text = "Build with zig",
-                .right_text = "Yves Biener (@yves-biener)",
-            };
-        }
+        left_text: []const u8 = "Build with zig",
+        right_text: []const u8 = "Yves Biener (@yves-biener)",
 
         pub fn element(this: *@This()) App.Element {
             return .{
@@ -141,7 +136,7 @@ pub fn InfoBanner(App: type) type {
             };
         }
 
-        fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
+        fn content(ctx: *anyopaque, model: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
             const this: *const @This() = @ptrCast(@alignCast(ctx));
             assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -154,6 +149,22 @@ pub fn InfoBanner(App: type) type {
                 cells[idx].cp = cp;
             }
 
+            switch (model.page) {
+                .about => {},
+                .blog => |path| if (path) |p| page: {
+                    const start_idx = (size.x -| p.len) / 2;
+                    if (start_idx <= this.left_text.len) break :page;
+
+                    for (start_idx.., p) |idx, cp| {
+                        // NOTE do not write over the contents of this `Container`'s `Size`
+                        if (idx == cells.len) break;
+
+                        cells[idx].style.fg = .default;
+                        cells[idx].cp = cp;
+                    }
+                },
+            }
+
             var start_idx = size.x -| this.right_text.len;
             if (start_idx <= this.left_text.len) start_idx = this.left_text.len + 1;