package handlers

import (
	"context"
	"encoding/json"
	"html/template"
	"log/slog"
	"net/http"

	"go.uber.org/fx"
	"sneak.berlin/go/webhooker/internal/database"
	"sneak.berlin/go/webhooker/internal/globals"
	"sneak.berlin/go/webhooker/internal/healthcheck"
	"sneak.berlin/go/webhooker/internal/logger"
	"sneak.berlin/go/webhooker/internal/session"
	"sneak.berlin/go/webhooker/templates"
)

// nolint:revive // HandlersParams is a standard fx naming convention
type HandlersParams struct {
	fx.In
	Logger      *logger.Logger
	Globals     *globals.Globals
	Database    *database.Database
	Healthcheck *healthcheck.Healthcheck
	Session     *session.Session
}

type Handlers struct {
	params    *HandlersParams
	log       *slog.Logger
	hc        *healthcheck.Healthcheck
	db        *database.Database
	session   *session.Session
	templates map[string]*template.Template
}

// parsePageTemplate parses a page-specific template set from the embedded FS.
// Each page template is combined with the shared base, htmlheader, and navbar templates.
func parsePageTemplate(pageFile string) *template.Template {
	return template.Must(
		template.ParseFS(templates.Templates, "htmlheader.html", "navbar.html", "base.html", pageFile),
	)
}

func New(lc fx.Lifecycle, params HandlersParams) (*Handlers, error) {
	s := new(Handlers)
	s.params = &params
	s.log = params.Logger.Get()
	s.hc = params.Healthcheck
	s.db = params.Database
	s.session = params.Session

	// Parse all page templates once at startup
	s.templates = map[string]*template.Template{
		"index.html":   parsePageTemplate("index.html"),
		"login.html":   parsePageTemplate("login.html"),
		"profile.html": parsePageTemplate("profile.html"),
	}

	lc.Append(fx.Hook{
		OnStart: func(ctx context.Context) error {
			return nil
		},
	})
	return s, nil
}

//nolint:unparam // r parameter will be used in the future for request context
func (s *Handlers) respondJSON(w http.ResponseWriter, r *http.Request, data interface{}, status int) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	if data != nil {
		err := json.NewEncoder(w).Encode(data)
		if err != nil {
			s.log.Error("json encode error", "error", err)
		}
	}
}

//nolint:unparam,unused // will be used for handling JSON requests
func (s *Handlers) decodeJSON(w http.ResponseWriter, r *http.Request, v interface{}) error {
	return json.NewDecoder(r.Body).Decode(v)
}

// TemplateData represents the common data passed to templates
type TemplateData struct {
	User      *UserInfo
	Version   string
	UserCount int64
	Uptime    string
}

// UserInfo represents user information for templates
type UserInfo struct {
	ID       string
	Username string
}

// renderTemplate renders a pre-parsed template with common data
func (s *Handlers) renderTemplate(w http.ResponseWriter, r *http.Request, pageTemplate string, data interface{}) {
	tmpl, ok := s.templates[pageTemplate]
	if !ok {
		s.log.Error("template not found", "template", pageTemplate)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	// Get user from session if available
	var userInfo *UserInfo
	sess, err := s.session.Get(r)
	if err == nil && s.session.IsAuthenticated(sess) {
		if username, ok := s.session.GetUsername(sess); ok {
			if userID, ok := s.session.GetUserID(sess); ok {
				userInfo = &UserInfo{
					ID:       userID,
					Username: username,
				}
			}
		}
	}

	// If data is a map, merge user info into it
	if m, ok := data.(map[string]interface{}); ok {
		m["User"] = userInfo
		if err := tmpl.Execute(w, m); err != nil {
			s.log.Error("failed to execute template", "error", err)
			http.Error(w, "Internal server error", http.StatusInternalServerError)
		}
		return
	}

	// Wrap data with base template data
	type templateDataWrapper struct {
		User *UserInfo
		Data interface{}
	}

	wrapper := templateDataWrapper{
		User: userInfo,
		Data: data,
	}

	if err := tmpl.Execute(w, wrapper); err != nil {
		s.log.Error("failed to execute template", "error", err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
	}
}