clawbot
f8ce8cef83
The template's files at a77fd30, without its history or LICENSE, after script/rename simplexcalc. Model: opus-5-5
115 lines
2.9 KiB
Go
115 lines
2.9 KiB
Go
package handlers
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import (
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"net/http"
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"strings"
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"github.com/dustin/go-humanize"
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"sneak.berlin/go/simplexcalc/internal/render"
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)
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// widgetListLimit bounds the index query. An unbounded SELECT is fine
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// on the day it is written and is the outage two years later.
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const widgetListLimit = 50
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// maxWidgetNameLen matches the maxlength on the form input. The form is
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// a courtesy; this is the rule.
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const maxWidgetNameLen = 200
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// Index renders the front page from the embedded template, listing the
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// most recent widgets.
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func (h *Handlers) Index() http.HandlerFunc {
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return func(w http.ResponseWriter, r *http.Request) {
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ctx := r.Context()
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widgets, err := h.params.Database.ListWidgets(ctx, widgetListLimit)
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if err != nil {
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h.fail(w, r, http.StatusInternalServerError, "Could not load widgets.", err)
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return
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}
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count, err := h.params.Database.CountWidgets(ctx)
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if err != nil {
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h.fail(w, r, http.StatusInternalServerError, "Could not count widgets.", err)
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return
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}
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data := render.IndexPage{
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Page: h.page(r),
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WidgetCount: count,
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Widgets: widgets,
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}
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err = h.params.Renderer.HTML(w, http.StatusOK, "index.html", data)
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if err != nil {
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h.fail(w, r, http.StatusInternalServerError, "Could not render the page.", err)
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}
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}
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}
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// CreateWidget handles the form POST. State-changing, so it is behind
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// CSRF; see internal/server/routes.go for where that is applied.
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func (h *Handlers) CreateWidget() http.HandlerFunc {
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return func(w http.ResponseWriter, r *http.Request) {
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// ParseForm reads the body, which BodyLimit has already capped:
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// an oversized submission fails here rather than being buffered
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// in full first.
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err := r.ParseForm()
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if err != nil {
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h.fail(w, r, http.StatusBadRequest, "Could not read the form.", err)
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return
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}
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name := strings.TrimSpace(r.PostFormValue("name"))
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if name == "" || len(name) > maxWidgetNameLen {
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h.fail(w, r, http.StatusBadRequest,
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"A widget needs a name of 1 to 200 characters.", errBadWidgetName)
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return
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}
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size, err := parseSize(r.PostFormValue("size"))
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if err != nil {
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h.fail(w, r, http.StatusBadRequest,
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"Size must be a byte count, like 4096 or 4KiB.", err)
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return
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}
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_, err = h.params.Database.CreateWidget(r.Context(), name, size)
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if err != nil {
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h.fail(w, r, http.StatusInternalServerError, "Could not save the widget.", err)
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return
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}
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// POST/redirect/GET: a reload must not repeat the write.
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http.Redirect(w, r, "/", http.StatusSeeOther)
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}
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}
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// parseSize accepts an empty value as zero and anything else as a
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// human-readable byte size.
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func parseSize(s string) (int64, error) {
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s = strings.TrimSpace(s)
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if s == "" {
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return 0, nil
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}
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n, err := humanize.ParseBytes(s)
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if err != nil {
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return 0, errBadWidgetSize
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}
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// A size beyond this is not a widget, it is a typo with a suffix.
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const maxWidgetSize = uint64(1) << 50
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if n > maxWidgetSize {
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return 0, errBadWidgetSize
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}
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return int64(n), nil
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}
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