package httpapi

import (
	"context"
	"encoding/json"
	"errors"
	"io"
	"net/http"

	"git.5iot.com/iotlcm-public/iotlcm-sms/internal/sms"
)

const maxRequestBody = 1 << 20

type Sender interface {
	Send(ctx context.Context, config sms.Config, message sms.Message) (sms.Result, error)
}

type SendRequest struct {
	Config sms.Config  `json:"config"`
	Params sms.Message `json:"params"`
}

type handler struct {
	sender Sender
}

func NewHandler(sender Sender) http.Handler {
	h := &handler{sender: sender}
	mux := http.NewServeMux()
	mux.HandleFunc("GET /healthz", h.health)
	mux.HandleFunc("POST /api/v1/sms/send", h.send)
	return mux
}

func (h *handler) health(w http.ResponseWriter, _ *http.Request) {
	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
}

func (h *handler) send(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, maxRequestBody)
	decoder := json.NewDecoder(r.Body)
	decoder.DisallowUnknownFields()

	var request SendRequest
	if err := decoder.Decode(&request); err != nil {
		writeJSON(w, http.StatusBadRequest, sms.Result{Code: 400, Message: "请求 JSON 无效: " + err.Error()})
		return
	}
	if err := decoder.Decode(&struct{}{}); !errors.Is(err, io.EOF) {
		writeJSON(w, http.StatusBadRequest, sms.Result{Code: 400, Message: "请求体只能包含一个 JSON 对象"})
		return
	}

	result, err := h.sender.Send(r.Context(), request.Config, request.Params)
	if err != nil {
		status := http.StatusBadGateway
		if errors.Is(err, sms.ErrInvalidRequest) || errors.Is(err, sms.ErrProviderNotFound) || errors.Is(err, sms.ErrSceneNotConfigured) {
			status = http.StatusBadRequest
		}
		writeJSON(w, status, result)
		return
	}
	writeJSON(w, http.StatusOK, result)
}

func writeJSON(w http.ResponseWriter, status int, value any) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(value)
}