| 1 | package main |
| 2 | |
| 3 | // 🤖 donate.go — checkout for the /donate page on the marketing site. Eleven |
| 4 | // has no funding; the page says so and asks nothing — but if someone wants |
| 5 | // to back the ideas (defiance of big tech, of over-complexity in software |
| 6 | // distribution; proceeds into the 11 factor principles and affordable, |
| 7 | // top-tier software), this mints the Stripe Checkout Session that takes |
| 8 | // their money. Same deliberate shape as the Enterprise page's checkout |
| 9 | // (enterprise.go): its own Stripe key (LCHAT_STRIPE_DONATE_KEY, sandbox |
| 10 | // until the explicit live flip), CORS pinned to the marketing origin, fixed |
| 11 | // server-side redirects, a global mint rate limit, and amounts constrained |
| 12 | // server-side. Pay what you want, floor €1.10 — the elevens' smallest coin. |
| 13 | |
| 14 | import ( |
| 15 | "encoding/json" |
| 16 | "fmt" |
| 17 | "io" |
| 18 | "log" |
| 19 | "net/http" |
| 20 | "net/url" |
| 21 | "strconv" |
| 22 | "strings" |
| 23 | "time" |
| 24 | ) |
| 25 | |
| 26 | const ( |
| 27 | // Minor units (cents/pence — identical numerals in every currency, like |
| 28 | // the Enterprise price list; we don't do exchange rates). |
| 29 | donateMinMinor = 110 // €1.10 — below this Stripe's fixed fee eats the gift |
| 30 | donateMaxMinor = 99_999_999 // Stripe's 8-digit single-payment cap |
| 31 | ) |
| 32 | |
| 33 | var donateCurrencies = map[string]bool{"eur": true, "usd": true, "gbp": true} |
| 34 | |
| 35 | // donateCheckout holds the page's Stripe config. nil on cloudServer = the |
| 36 | // feature is off and the endpoint answers 501. |
| 37 | type donateCheckout struct { |
| 38 | key string |
| 39 | apiBase string |
| 40 | origin string |
| 41 | client *http.Client |
| 42 | limiter mintLimiter |
| 43 | } |
| 44 | |
| 45 | func newDonateCheckout(key, apiBase, origin string) *donateCheckout { |
| 46 | key = strings.TrimSpace(key) |
| 47 | if key == "" { |
| 48 | return nil |
| 49 | } |
| 50 | return &donateCheckout{ |
| 51 | key: key, |
| 52 | apiBase: apiBase, |
| 53 | origin: strings.TrimRight(origin, "/"), |
| 54 | client: &http.Client{Timeout: 20 * time.Second}, |
| 55 | limiter: mintLimiter{max: 30, window: time.Minute}, |
| 56 | } |
| 57 | } |
| 58 | |
| 59 | // donateCORS stamps the CORS headers; single marketing origin, never *. |
| 60 | func (s *cloudServer) donateCORS(w http.ResponseWriter) bool { |
| 61 | if s.donate == nil { |
| 62 | return false |
| 63 | } |
| 64 | h := w.Header() |
| 65 | h.Set("Access-Control-Allow-Origin", s.donate.origin) |
| 66 | h.Set("Vary", "Origin") |
| 67 | return true |
| 68 | } |
| 69 | |
| 70 | // donatePreflightHandler: OPTIONS /api/donate/checkout. |
| 71 | func (s *cloudServer) donatePreflightHandler(w http.ResponseWriter, r *http.Request) { |
| 72 | if !s.donateCORS(w) { |
| 73 | w.WriteHeader(http.StatusNotImplemented) |
| 74 | return |
| 75 | } |
| 76 | h := w.Header() |
| 77 | h.Set("Access-Control-Allow-Methods", "POST") |
| 78 | h.Set("Access-Control-Allow-Headers", "Content-Type") |
| 79 | h.Set("Access-Control-Max-Age", "86400") |
| 80 | w.WriteHeader(http.StatusNoContent) |
| 81 | } |
| 82 | |
| 83 | // donateCheckoutHandler: POST /api/donate/checkout — mint a one-time |
| 84 | // Checkout Session. Body: {"amount_minor": n, "currency": "eur"}. |
| 85 | func (s *cloudServer) donateCheckoutHandler(w http.ResponseWriter, r *http.Request) { |
| 86 | if !s.donateCORS(w) { |
| 87 | writeControlErr(w, http.StatusNotImplemented, "unavailable", "donations are not configured") |
| 88 | return |
| 89 | } |
| 90 | d := s.donate |
| 91 | if !d.limiter.allow(time.Now()) { |
| 92 | writeControlErr(w, http.StatusTooManyRequests, "slow_down", "the till is busy — try again in a minute") |
| 93 | return |
| 94 | } |
| 95 | var req struct { |
| 96 | AmountMinor int `json:"amount_minor"` |
| 97 | Currency string `json:"currency"` |
| 98 | } |
| 99 | if err := json.NewDecoder(io.LimitReader(r.Body, 4<<10)).Decode(&req); err != nil { |
| 100 | writeControlErr(w, http.StatusBadRequest, "bad_request", "invalid JSON body") |
| 101 | return |
| 102 | } |
| 103 | cur := strings.ToLower(strings.TrimSpace(req.Currency)) |
| 104 | if !donateCurrencies[cur] { |
| 105 | writeControlErr(w, http.StatusBadRequest, "bad_request", "currency must be eur, usd or gbp") |
| 106 | return |
| 107 | } |
| 108 | if req.AmountMinor < donateMinMinor { |
| 109 | writeControlErr(w, http.StatusBadRequest, "bad_request", "the smallest donation is 1.10 — below that the card fee eats the gift") |
| 110 | return |
| 111 | } |
| 112 | if req.AmountMinor > donateMaxMinor { |
| 113 | writeControlErr(w, http.StatusBadRequest, "over_stripe_cap", "Stripe cannot carry this much money in one payment — split it, or talk to us") |
| 114 | return |
| 115 | } |
| 116 | checkoutURL, err := d.createSession(cur, req.AmountMinor) |
| 117 | if err != nil { |
| 118 | log.Printf("cloud: donate checkout (%s %d): %v", cur, req.AmountMinor, err) |
| 119 | writeControlErr(w, http.StatusBadGateway, "checkout_failed", "couldn't start the checkout — please try again") |
| 120 | return |
| 121 | } |
| 122 | writeJSON(w, http.StatusOK, map[string]any{"url": checkoutURL}) |
| 123 | } |
| 124 | |
| 125 | // createSession builds the hosted page: one inline price_data line item, no |
| 126 | // customer identity, fixed redirects back to /donate/. |
| 127 | func (d *donateCheckout) createSession(currency string, amountMinor int) (string, error) { |
| 128 | form := url.Values{} |
| 129 | form.Set("mode", "payment") |
| 130 | form.Set("line_items[0][price_data][currency]", currency) |
| 131 | form.Set("line_items[0][price_data][product_data][name]", "Donation to Eleven") |
| 132 | form.Set("line_items[0][price_data][unit_amount]", strconv.Itoa(amountMinor)) |
| 133 | form.Set("line_items[0][quantity]", "1") |
| 134 | form.Set("metadata[donation]", "1") |
| 135 | form.Set("success_url", d.origin+"/donate/?thanks=1") |
| 136 | form.Set("cancel_url", d.origin+"/donate/") |
| 137 | |
| 138 | req, err := http.NewRequest("POST", d.apiBase+"/v1/checkout/sessions", strings.NewReader(form.Encode())) |
| 139 | if err != nil { |
| 140 | return "", err |
| 141 | } |
| 142 | req.Header.Set("Authorization", "Bearer "+d.key) |
| 143 | req.Header.Set("Content-Type", "application/x-www-form-urlencoded") |
| 144 | resp, err := d.client.Do(req) |
| 145 | if err != nil { |
| 146 | return "", err |
| 147 | } |
| 148 | defer resp.Body.Close() |
| 149 | var body struct { |
| 150 | URL string `json:"url"` |
| 151 | Error struct { |
| 152 | Message string `json:"message"` |
| 153 | } `json:"error"` |
| 154 | } |
| 155 | if err := json.NewDecoder(io.LimitReader(resp.Body, 1<<20)).Decode(&body); err != nil { |
| 156 | return "", fmt.Errorf("stripe: HTTP %d (unparseable body)", resp.StatusCode) |
| 157 | } |
| 158 | if resp.StatusCode != http.StatusOK || body.URL == "" { |
| 159 | return "", fmt.Errorf("stripe: HTTP %d: %s", resp.StatusCode, body.Error.Message) |
| 160 | } |
| 161 | return body.URL, nil |
| 162 | } |
| 163 | |
amadan