package voter

import (
	"context"

	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

type Voter interface {
	Vote(ctx context.Context, subject interface{}, obj interface{}, action interface{}) (Decision, error)
}

type Strategy func(ctx context.Context, decisions []Decision) (Decision, error)

type Manager struct {
	strategy Strategy
	voters   []Voter
}

func (m *Manager) Authorized(ctx context.Context, subject interface{}, obj interface{}, action interface{}) (Decision, error) {
	decisions := make([]Decision, 0, len(m.voters))

	logger.Debug(
		ctx,
		"checking authorization",
		logger.F("subject", subject),
		logger.F("object", obj),
		logger.F("action", action),
	)

	for _, v := range m.voters {
		dec, err := v.Vote(ctx, subject, obj, action)
		if err != nil {
			return Deny, errors.WithStack(err)
		}

		decisions = append(decisions, dec)
	}

	result, err := m.strategy(ctx, decisions)
	if err != nil {
		return Deny, errors.WithStack(err)
	}

	logger.Debug(
		ctx,
		"authorization checked",
		logger.F("subject", subject),
		logger.F("object", obj),
		logger.F("action", action),
		logger.F("result", AsString(result)),
	)

	return result, nil
}

func NewManager(strategy Strategy, voters ...Voter) *Manager {
	return &Manager{strategy, voters}
}