114 lines
3.2 KiB
Go
114 lines
3.2 KiB
Go
// This file is part of birdtown-visit-counter, and is © 2024 Alexander Khodyrev.
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//
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// Full source code is available at https://git.akho.name/akho/birdtown-visit-counter
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//
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// birdtown-visit-counter is free software: you can redistribute it and/or
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// modify it under the terms of the GNU Affero General Public License as
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// published by the Free Software Foundation, either version 3 of the License,
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// or (at your option) any later version.
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//
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// birdtown-visit-counter is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License
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// for more details.
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//
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// You should have received a copy of the GNU Affero General Public License along
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// with birdtown-visit-counter. If not, see <https://www.gnu.org/licenses/>.
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package main
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import (
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"encoding/json"
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"flag"
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"log"
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"net/http"
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"os"
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"strconv"
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"sync"
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)
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type visitsStore struct {
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m map[string]int
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*sync.RWMutex
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}
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func (s *visitsStore) visit(ending string) int {
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s.Lock()
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defer s.Unlock()
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oldVisits, has := s.m[ending]
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var newVisits int
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if has {
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newVisits = oldVisits + 1
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} else {
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newVisits = 1
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}
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s.m[ending] = newVisits
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return newVisits
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}
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type visitsHandler struct {
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store *visitsStore
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}
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func (h *visitsHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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// CORS: this is expected to be called from a different domain,
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// hoops require jumping
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w.Header().Set("Access-Control-Allow-Origin", "*")
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w.Header().Set("Access-Control-Max-Age", "86400")
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w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS")
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w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization")
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w.Header().Set("content-type", "application/json")
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if r.Method == http.MethodPost {
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var s string
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if err := json.NewDecoder(r.Body).Decode(&s); err != nil {
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w.WriteHeader(http.StatusInternalServerError)
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w.Write([]byte("cannot parse data"))
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return
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}
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w.WriteHeader(http.StatusOK)
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w.Write(([]byte)(strconv.Itoa(h.store.visit(s))))
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return
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}
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if r.Method == http.MethodGet {
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h.store.Lock()
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jsonBytes, err := json.Marshal(h.store.m)
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h.store.Unlock()
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if err != nil {
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w.WriteHeader(http.StatusInternalServerError)
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w.Write([]byte("cannot serialize"))
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return
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}
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w.WriteHeader(http.StatusOK)
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w.Write(jsonBytes)
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return
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}
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if r.Method == http.MethodOptions {
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w.WriteHeader(http.StatusOK)
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return
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}
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w.Header().Set("Allow", "POST, GET, OPTIONS")
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w.WriteHeader(http.StatusMethodNotAllowed)
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}
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func main() {
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addr := flag.String("addr", ":11568", "Listen address")
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initialFile := flag.String("file", "visits.json", "File with initial data in JSON format")
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flag.Parse()
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initialVisits := make(map[string]int)
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initialVisitsJson, err := os.ReadFile(*initialFile)
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if err == nil {
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json.Unmarshal(initialVisitsJson, &initialVisits)
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} else {
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log.Println("initial file", *initialFile, "could not be read, defaulting to empty data")
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}
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store := visitsStore{m: initialVisits, RWMutex: &sync.RWMutex{}}
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visitsH := &visitsHandler{store: &store}
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http.Handle("/", visitsH)
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log.Println("Starting web server...")
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http.ListenAndServe(*addr, nil)
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}
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