package main

import (
	"net/http"
	"os"
	"path/filepath"
)

// Root todo.txt rail widget (assets/todo-rail.js). /_todo reads and writes the
// single wiki-root todo.txt — the path is fixed, so there is no traversal
// surface. GET returns the raw text (404 when the file is absent, which the
// widget treats as "render nothing"); POST replaces the whole file atomically.
// Unlike the index.md save path, empty content does NOT delete the file: the
// widget has no in-UI way to recreate it, so an empty save keeps an empty file.

func (h *handler) todoPath() string {
	return filepath.Join(h.root, "todo.txt")
}

func (h *handler) handleTodo(w http.ResponseWriter, r *http.Request) {
	if !h.checkAuth(w, r) {
		return
	}
	switch r.Method {
	case http.MethodGet:
		h.handleTodoGet(w, r)
	case http.MethodPost:
		h.handleTodoPost(w, r)
	default:
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	}
}

func (h *handler) handleTodoGet(w http.ResponseWriter, r *http.Request) {
	data, err := os.ReadFile(h.todoPath())
	if err != nil {
		if os.IsNotExist(err) {
			http.NotFound(w, r)
			return
		}
		http.Error(w, "read failed: "+err.Error(), http.StatusInternalServerError)
		return
	}
	// The rail re-fetches on every page load; a heuristically cached copy
	// would show stale todos after an edit.
	w.Header().Set("Cache-Control", "no-store")
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	w.Write(data)
}

func (h *handler) handleTodoPost(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseForm(); err != nil {
		http.Error(w, "bad request", http.StatusBadRequest)
		return
	}
	content := r.FormValue("content")
	if err := writeFileAtomic(h.todoPath(), []byte(content), 0644); err != nil {
		http.Error(w, "write failed: "+err.Error(), http.StatusInternalServerError)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}