package server

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

	"ddc/internal/diskspace"
	"ddc/internal/files"
	"ddc/internal/jobs"
	"ddc/internal/preferences"
)

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

func writeError(writer http.ResponseWriter, status int, message string) {
	writeJSON(writer, status, map[string]string{"error": message})
}

func writeFailure(writer http.ResponseWriter, err error) {
	writeError(writer, statusFor(err), err.Error())
}

func decodeJSON(request *http.Request, target any) error {
	decoder := json.NewDecoder(request.Body)
	decoder.DisallowUnknownFields()
	return decoder.Decode(target)
}

func statusFor(err error) int {
	switch {
	case errors.Is(err, jobs.ErrJobNotFound):
		return http.StatusNotFound
	case errors.Is(err, jobs.ErrJobBusy), errors.Is(err, files.ErrDestinationExists):
		return http.StatusConflict
	case errors.Is(err, jobs.ErrInvalidRequest), errors.Is(err, preferences.ErrInvalid):
		return http.StatusBadRequest
	case errors.Is(err, diskspace.ErrInsufficientSpace):
		return http.StatusInsufficientStorage
	default:
		return http.StatusInternalServerError
	}
}