package controller

import (
	"bytes"
	"encoding/json"
	"io"
	"net/http"
	"strconv"

	"datasource/store"
)

type Controller struct {
	store *store.Store
}

func NewController(store *store.Store) *Controller {
	return &Controller{store: store}
}

func (c *Controller) GetMetrics(w http.ResponseWriter, r *http.Request) {
	query := r.URL.Query()

	service := query.Get("service")
	if service == "" {
		http.Error(w, "service cannot be empty", http.StatusBadRequest)
		return
	}

	t0, err := strconv.ParseInt(query.Get("t0"), 10, 64)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	t1, err := strconv.ParseInt(query.Get("t1"), 10, 64)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	if t0 > t1 {
		http.Error(w, "t0 cannot be larger than t1", http.StatusBadRequest)
		return
	}

	metrics, err := c.store.GetMetrics(r.Context(), service, t0, t1)
	if err != nil {
		// todo (david): log internal server error
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	var buf bytes.Buffer

	if err := json.NewEncoder(&buf).Encode(metrics); err != nil {
		// todo (david): log internal server error
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")

	if _, err := io.Copy(w, &buf); err != nil {
		// too late to return http.StatusInternalServerError
		// todo (david): log internal server error
	}
}

// todo (david)
// func (c *Controller) DeleteMetrics(w http.ResponseWriter, r *http.Request) {}