package main

import (
	"embed"
	"encoding/json"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"strconv"
	"time"

	"github.com/gorilla/mux"
)

//go:embed *.js *.html.in *.css *.png robots.txt
var content embed.FS

func handleEntryOptions(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Access-Control-Allow-Origin", "*")
	w.Header().Set("Access-Control-Allow-Methods", "OPTIONS, POST, GET")
	w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
	w.WriteHeader(http.StatusNoContent)
}

func handleEntryPost(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Access-Control-Allow-Origin", "*")
	w.Header().Set("Access-Control-Allow-Methods", "OPTIONS, POST, GET")
	w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
	var entry Entry
	err := json.NewDecoder(r.Body).Decode(&entry)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	err = InsertEntry(&entry)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	log.Println("New entry for", entry.Location)
}

type EntriesPage struct {
	Total   uint    `json:"total"`
	Offset  uint    `json:"offset"`
	Size    uint    `json:"size"`
	Entries []Entry `json:"entries"`
}

func handleEntryGet(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Access-Control-Allow-Origin", "*")
	w.Header().Set("Access-Control-Allow-Methods", "OPTIONS, POST, GET")
	w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
	from64, _ := strconv.ParseUint(r.FormValue("from"), 10, 32)
	from := uint(from64)
	count, err := CountEntries()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	entries, err := ListEntries(from, 1000)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	if entries == nil {
		entries = []Entry{}
	}
	page := EntriesPage{Total: count, Offset: from, Size: uint(len(entries)), Entries: entries}
	err = json.NewEncoder(w).Encode(&page)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
}

type Stat struct {
	Title       string
	Description string
}

type Home struct {
	Stats []Stat
}

func count(title string, amount int) Stat {
	return Stat{title, fmt.Sprintf("%d visits", amount)}
}

func handleHome(pathname string) func(http.ResponseWriter, *http.Request) {
	t := template.Must(template.ParseFS(content, pathname))
	return func(w http.ResponseWriter, r *http.Request) {
		var home Home
		now := time.Now().UTC()
		last_day, err := EntriesSince(now.AddDate(0, 0, -1))
		if err == nil {
			home.Stats = append(home.Stats, count("Last 24 hours", len(last_day)))
		}
		last_month, err := EntriesSince(now.AddDate(0, 0, -30))
		if err == nil {
			home.Stats = append(home.Stats, count("Last 30 days", len(last_month)))
		}
		total, err := CountEntries()
		if err == nil {
			home.Stats = append(home.Stats, count("Total", int(total)))
		}
		first, err := FirstEntry()
		if err == nil {
			home.Stats = append(home.Stats, Stat{"First visit", first.StartedAt.Format("_2 January 2006, 15:04")})
		}
		if len(home.Stats) < 1 {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		t.Execute(w, home)
	}
}

func handleRequests(port string) {
	router := mux.NewRouter()
	router.HandleFunc("/entries", handleEntryOptions).Methods("OPTIONS")
	router.HandleFunc("/entries", handleEntryPost).Methods("POST")
	router.HandleFunc("/entries", handleEntryGet).Methods("GET")
	router.HandleFunc("/", handleHome("index.html.in")).Methods("GET")
	router.PathPrefix("/").Handler(http.FileServer(http.FS(content)))
	log.Fatal(http.ListenAndServe(port, router))
}

func main() {
	log.Println("Starting up")
	cfg := LoadConfig()
	InitEntries(cfg.DB)
	defer CloseEntries()
	handleRequests(cfg.Port)
}