package templates

import (
	"bytes"
	"fmt"
	"html/template"
	"io/fs"
	"net/http"
	"os"
	"path/filepath"
	"strings"

	"github.com/gorilla/csrf"
	"github.com/mattnite/forgejo-tickets/internal/auth"
	"github.com/mattnite/forgejo-tickets/internal/middleware"
	"github.com/mattnite/forgejo-tickets/internal/models"
)

type Renderer struct {
	templates map[string]*template.Template
}

type PageData struct {
	User      *models.User
	CSRFToken string
	Flash     *Flash
	Data      interface{}
}

type Flash struct {
	Type    string // "success", "error", "info"
	Message string
}

func NewRenderer() (*Renderer, error) {
	r := &Renderer{
		templates: make(map[string]*template.Template),
	}

	if err := r.parseTemplates(); err != nil {
		return nil, err
	}

	return r, nil
}

func (r *Renderer) parseTemplates() error {
	templateDir := "web/templates"

	partials, err := filepath.Glob(filepath.Join(templateDir, "partials", "*.html"))
	if err != nil {
		return fmt.Errorf("glob partials: %w", err)
	}

	err = filepath.WalkDir(filepath.Join(templateDir, "pages"), func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() || !strings.HasSuffix(path, ".html") {
			return nil
		}

		layout := filepath.Join(templateDir, "layouts", "base.html")
		if strings.Contains(path, "admin") {
			layout = filepath.Join(templateDir, "layouts", "admin.html")
		}

		if _, err := os.Stat(layout); os.IsNotExist(err) {
			return nil
		}

		files := []string{layout}
		files = append(files, partials...)
		files = append(files, path)

		name := strings.TrimPrefix(path, filepath.Join(templateDir, "pages")+"/")
		name = strings.TrimSuffix(name, ".html")

		tmpl, err := template.New(filepath.Base(layout)).Funcs(templateFuncs()).ParseFiles(files...)
		if err != nil {
			return fmt.Errorf("parse template %s: %w", name, err)
		}

		r.templates[name] = tmpl
		return nil
	})
	if err != nil {
		return err
	}

	return nil
}

func (r *Renderer) Render(w http.ResponseWriter, req *http.Request, name string, data interface{}) {
	tmpl, ok := r.templates[name]
	if !ok {
		http.Error(w, fmt.Sprintf("template %q not found", name), http.StatusInternalServerError)
		return
	}

	pd := PageData{
		User:      auth.CurrentUserFromRequest(req),
		CSRFToken: csrf.Token(req),
		Data:      data,
	}

	if flashType, flashMsg := middleware.GetFlash(req, w); flashMsg != "" {
		pd.Flash = &Flash{Type: flashType, Message: flashMsg}
	}

	var buf bytes.Buffer
	if err := tmpl.Execute(&buf, pd); err != nil {
		http.Error(w, fmt.Sprintf("render template: %v", err), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	buf.WriteTo(w)
}

func (r *Renderer) RenderError(w http.ResponseWriter, req *http.Request, status int, message string) {
	w.WriteHeader(status)
	if tmpl, ok := r.templates["error"]; ok {
		pd := PageData{
			User:      auth.CurrentUserFromRequest(req),
			CSRFToken: csrf.Token(req),
			Data:      map[string]interface{}{"Status": status, "Message": message},
		}
		var buf bytes.Buffer
		if err := tmpl.Execute(&buf, pd); err == nil {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			buf.WriteTo(w)
			return
		}
	}
	http.Error(w, message, status)
}