package main

import (
	"context"
	"fmt"
	"github.com/redis/go-redis/v9"
	"log"
	"encoding/json"
	"net/http"
	"html/template"
	"strconv"
)

type todo struct {
	Id int
	Title string
	Completed bool
}
var maxId int = 0

var ctx = context.Background()
var rdb = redis.NewClient(&redis.Options{
        Addr:     "localhost:6379",
        Password: "", // no password set
        DB:       0,  // use default DB
})

func GetTodos() []todo {
	var cursor uint64 = 0
	todosJson, cursor, err := rdb.Scan(ctx, cursor, "todo:*", 20).Result()
	if err != nil {
		panic(err)
	}
	var todos []todo = make([]todo, len(todosJson))
	for idx, todoJson := range todosJson {
		todoJson :=  rdb.Get(ctx, todoJson).Val()
		fmt.Println("Todo: %s", todoJson)
		err = json.Unmarshal([]byte(todoJson), &todos[idx])
		if err != nil {
			panic(err)
		}
		if todos[idx].Id > maxId {
			maxId = todos[idx].Id
		}
	}
	return todos
}

func GetTodoById(id int) todo {
	todoJson, err := rdb.Get(ctx, fmt.Sprintf("todo:%d", id)).Result()
	if err != nil {
		panic(err)
	}
	
	var todo todo
	err = json.Unmarshal([]byte(todoJson), &todo)
	if err != nil {
		panic(err)
	}
	return todo
}

func SetTodo(todo todo) {
	todoJson, err := json.Marshal(todo)
	if err != nil {
		panic(err)
	}
	key := fmt.Sprintf("todo:%d", todo.Id)
	err = rdb.Set(ctx, key, string(todoJson), 0).Err()
	if err != nil {
		panic(err)
	}
	fmt.Println("Set todo: %s", todoJson)
}

func DeleteTodoById(id int) {
	err := rdb.Del(ctx, fmt.Sprintf("todo:%d", id)).Err()
	if err != nil {
		panic(err)
	}
}

func IndexHandler(w http.ResponseWriter, r *http.Request) {
	t, _ := template.ParseFiles("templates/index.html")
	t.Execute(w, nil)
}

func TodosHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method == "POST" {
		r.ParseForm()
		todoTitle := r.Form.Get("title")
		SetTodo(todo{Id: maxId + 1, Title: todoTitle, Completed: false})
	}
	todos := GetTodos()
	t, _ := template.ParseFiles("templates/todos.html")
	t.Execute(w, todos)
}

func ToggleTodoHandler(w http.ResponseWriter, r *http.Request) {
	todoId, err := strconv.Atoi(r.URL.Path)
	if err != nil {
		panic(err)
	}
	fmt.Println("Todo Id: %d", todoId)
	todo := GetTodoById(todoId)
	todo.Completed = !todo.Completed
	SetTodo(todo)
	TodosHandler(w, r)
	return
}

func TodoHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != "DELETE" {
		w.WriteHeader(http.StatusMethodNotAllowed)
		fmt.Fprintf(w, "Method %s not allowed", r.Method)
		return
	}
	todoId, err := strconv.Atoi(r.URL.Path)
	if err != nil {
		panic(err)
	}
	fmt.Println("Todo Id: %d", todoId)
	DeleteTodoById(todoId)
	TodosHandler(w, r)
	return
}


func main() {
	fmt.Println("Starting web server on port 8080")
        fs := http.FileServer(http.Dir("./static"))
        http.Handle("/static/", http.StripPrefix("/static/", fs))
	http.HandleFunc("/", IndexHandler)
	http.HandleFunc("/todos", TodosHandler)
	togglePath := "/toggle-todo/"
	http.Handle(togglePath, http.StripPrefix(togglePath, http.HandlerFunc(ToggleTodoHandler)))
	todoPath := "/todo/"
	http.Handle(todoPath, http.StripPrefix(todoPath, http.HandlerFunc(TodoHandler)))

	log.Fatal(http.ListenAndServe(":8080", nil))
}