feat: add modular template renderer

internal/app/app.go

@@ -3,8 +3,10 @@ package app
 import (
 	"mal/internal/database"
 	"mal/internal/server"
+	"mal/internal/templates"
 
 	"github.com/gin-gonic/gin"
+	"github.com/gin-gonic/gin/render"
 	"go.uber.org/fx"
 )
 
@@ -12,7 +14,11 @@ func NewApp() *fx.App {
 	return fx.New(
 		database.Module,
 		jikan.Module,
+		templates.Module,
 		server.Module,
+		fx.Decorate(func(r *templates.Renderer) render.HTMLRender {
+			return r
+		}),
 		fx.Invoke(func(r *gin.Engine, registers []server.RouteRegister) {
 			server.RegisterRoutes(r, registers)
 		}),

internal/server/server.go

@@ -8,6 +8,7 @@ import (
 	"os"
 
 	"github.com/gin-gonic/gin"
+	"github.com/gin-gonic/gin/render"
 	"go.uber.org/fx"
 )
 
@@ -16,12 +17,13 @@ var Module = fx.Options(
 	fx.Invoke(RunServer),
 )
 
-func ProvideRouter() *gin.Engine {
+func ProvideRouter(htmlRender render.HTMLRender) *gin.Engine {
 	if os.Getenv("GIN_MODE") == "" {
 		gin.SetMode(gin.ReleaseMode)
 	}
 	r := gin.New()
 	r.Use(gin.Logger(), gin.Recovery())
+	r.HTMLRender = htmlRender
 	return r
 }
 

internal/templates/renderer.go

@@ -0,0 +1,208 @@
+package templates
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"html/template"
+	"io"
+	"log"
+	"net/http"
+	"path/filepath"
+	"slices"
+	"strconv"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+	"github.com/gin-gonic/gin/render"
+	"go.uber.org/fx"
+)
+
+// FS is the interface for template filesystem, to be provided by the main app or a mock.
+type FS interface {
+	ReadFile(name string) ([]byte, error)
+	ReadDir(name string) ([]osDirEntry, error)
+}
+
+// We will use embed.FS but wrapped in an interface if needed, or just use it directly.
+// For now let's assume we pass the root embed.FS to the constructor.
+
+type Renderer struct {
+	templates map[string]*template.Template
+}
+
+var Module = fx.Options(
+	fx.Provide(ProvideRenderer),
+)
+
+func ProvideRenderer() (*Renderer, error) {
+	// In the final version, this will use an embedded FS.
+	// For now, let's keep it working with the local filesystem but as an fx service.
+	r := &Renderer{
+		templates: make(map[string]*template.Template),
+	}
+
+	funcs := template.FuncMap{
+		"dict": func(values ...any) map[string]any {
+			m := make(map[string]any)
+			for i := 0; i < len(values)-1; i += 2 {
+				key, ok := values[i].(string)
+				if !ok {
+					continue
+				}
+				m[key] = values[i+1]
+			}
+			return m
+		},
+		"json": func(v any) template.HTMLAttr {
+			b, _ := json.Marshal(v)
+			return template.HTMLAttr(b)
+		},
+		"genresParams": func(genres []int) string {
+			if len(genres) == 0 {
+				return ""
+			}
+			var s strings.Builder
+			for _, g := range genres {
+				s.WriteString("genres=" + fmt.Sprintf("%d", g) + "&")
+			}
+			return s.String()[:len(s.String())-1]
+		},
+		"hasGenre": func(id int, genres []int) bool {
+			return slices.Contains(genres, id)
+		},
+		"add": func(a, b int) int {
+			return a + b
+		},
+		"sub": func(a, b int) int {
+			return a - b
+		},
+		"mul": func(a, b float64) float64 {
+			return a * b
+		},
+		"imul": func(a, b int) int {
+			return a * b
+		},
+		"div": func(a, b float64) float64 {
+			if b == 0 {
+				return 0
+			}
+			return a / b
+		},
+		"ceilDiv": func(a, b int) int {
+			if b == 0 {
+				return 0
+			}
+			return (a + b - 1) / b
+		},
+		"toFloat": func(a int) float64 {
+			return float64(a)
+		},
+		"seq": func(v any) []int {
+			var count int
+			switch n := v.(type) {
+			case int:
+				count = n
+			case int64:
+				count = int(n)
+			default:
+				count = 0
+			}
+			res := make([]int, count)
+			for i := 0; i < count; i++ {
+				res[i] = i
+			}
+			return res
+		},
+		"min": func(a, b int) int {
+			if a < b {
+				return a
+			}
+			return b
+		},
+		"int": func(v any) int {
+			switch n := v.(type) {
+			case int:
+				return n
+			case int64:
+				return int(n)
+			case float64:
+				return int(n)
+			case string:
+				i, _ := strconv.Atoi(n)
+				return i
+			default:
+				return 0
+			}
+		},
+		"percent": func(current, total float64) float64 {
+			if total == 0 {
+				return 0
+			}
+			return (current / total) * 100
+		},
+	}
+
+	pages, err := filepath.Glob(filepath.Join(".", "templates", "*.gohtml"))
+	if err != nil {
+		return nil, err
+	}
+
+	components, err := filepath.Glob(filepath.Join(".", "templates", "components", "*.gohtml"))
+	if err != nil {
+		return nil, err
+	}
+
+	for _, page := range pages {
+		name := filepath.Base(page)
+		if name == "base.gohtml" {
+			continue
+		}
+
+		tmpl := template.New(name).Funcs(funcs)
+		tmpl = template.Must(tmpl.ParseFiles(filepath.Join(".", "templates", "base.gohtml")))
+		if len(components) > 0 {
+			tmpl = template.Must(tmpl.ParseFiles(components...))
+		}
+		tmpl = template.Must(tmpl.ParseFiles(page))
+
+		r.templates[name] = tmpl
+	}
+
+	return r, nil
+}
+
+func (r *Renderer) Instance(name string, data any) render.Render {
+	return HTMLRender{
+		Renderer: r,
+		Name:     name,
+		Data:     data,
+	}
+}
+
+type HTMLRender struct {
+	Renderer *Renderer
+	Name     string
+	Data     any
+}
+
+func (h HTMLRender) Render(w http.ResponseWriter) error {
+	tmpl, ok := h.Renderer.templates[h.Name]
+	if !ok {
+		return fmt.Errorf("template %s not found", h.Name)
+	}
+	return tmpl.ExecuteTemplate(w, "base.gohtml", h.Data)
+}
+
+func (h HTMLRender) WriteContentType(w http.ResponseWriter) {
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+}
+
+// ExecuteFragment is for HTMX partials
+func (r *Renderer) ExecuteFragment(w io.Writer, name string, block string, data any) error {
+	tmpl, ok := r.templates[name]
+	if !ok {
+		return fmt.Errorf("template %s not found", name)
+	}
+	return tmpl.ExecuteTemplate(w, block, data)
+}