package domain

import (
	"context"
	"errors"
	"strings"
	"time"

	"github.com/zitadel/zitadel/backend/v3/storage/database"
	"github.com/zitadel/zitadel/internal/api/authz"
	"github.com/zitadel/zitadel/internal/eventstore"
	"github.com/zitadel/zitadel/internal/repository/session"
	"github.com/zitadel/zitadel/internal/zerrors"
)

type DeleteSessionCommand struct {
	ID                  string `json:"id"`
	Token               string `json:"token"`
	MustCheckPermission bool   `json:"mustCheckPermission,omitempty"`

	// DeletedAt is set after successful execution.
	DeletedAt time.Time `json:"deletedAt,omitempty"`
	// deletedRows is set after successful execution, used to determine if the session was deleted or not.
	deletedRows int64
}

func NewDeleteSessionCommand(
	id string,
	token string,
	mustCheckPermission bool,
) *DeleteSessionCommand {
	return &DeleteSessionCommand{
		ID:                  id,
		Token:               token,
		MustCheckPermission: mustCheckPermission,
	}
}

// RequiresTransaction implements [Transactional].
func (cmd *DeleteSessionCommand) RequiresTransaction() {}

// Events implements [Commander].
func (cmd *DeleteSessionCommand) Events(ctx context.Context, opts *InvokeOpts) ([]eventstore.Command, error) {
	if cmd.deletedRows == 0 {
		return nil, nil
	}
	return []eventstore.Command{
		session.NewTerminateEvent(ctx, &session.NewAggregate(cmd.ID, authz.GetInstance(ctx).InstanceID()).Aggregate),
	}, nil
}

const (
	ErrSessionTokenInvalid    = "ErrSessionTokenInvalid"
	ErrMoreThanOneRowAffected = "ErrMoreThanOneRowAffected"
	ErrIDMissing              = "ErrIDMissing"
	ErrMissingPermission      = "ErrMissingPermission"
	ErrInternal               = "ErrInternal"
)

func (cmd *DeleteSessionCommand) sessionDeletePermissionCheckCondition(ctx context.Context, sessionRepo SessionRepository, decryptor SessionTokenDecryptor) (database.Condition, error) {
	if !cmd.MustCheckPermission {
		return nil, nil
	}
	if cmd.Token != "" {
		sessionID, tokenID, err := decryptor(ctx, cmd.Token)
		if err != nil || sessionID != cmd.ID {
			return nil, zerrors.ThrowPermissionDenied(err, ErrSessionTokenInvalid, "Errors.Session.Token.Invalid")
		}
		return database.Or(
			sessionRepo.TokenIDCondition(tokenID),
			database.PermissionCheck(SessionDeletePermission, true),
		), nil
	}
	return database.Or(
		sessionRepo.UserIDCondition(authz.GetCtxData(ctx).UserID),
		database.PermissionCheck(SessionDeletePermission, true), // TODO: implement check once permissions are implemented
	), nil
}

// Execute implements [Commander].
func (cmd *DeleteSessionCommand) Execute(ctx context.Context, opts *InvokeOpts) (err error) {
	sessionRepo := opts.sessionRepo
	instance := authz.GetInstance(ctx)

	permCheck, err := cmd.sessionDeletePermissionCheckCondition(ctx, sessionRepo, opts.sessionTokenDecryptor)
	if err != nil {
		return err
	}

	deletedRows, deletedAt, err := sessionRepo.Delete(ctx, opts.DB(),
		sessionRepo.PrimaryKeyCondition(instance.InstanceID(), cmd.ID),
		permCheck,
	)
	if err != nil {
		if errors.Is(err, new(database.PermissionError)) {
			return zerrors.ThrowPermissionDenied(err, ErrMissingPermission,
				"insufficient permissions to delete session, require `session.delete` permission, ownership of the session or current session token")
		}
		return zerrors.ThrowInternal(err, ErrInternal, "an unexpected error occurred while deleting the session")
	}

	if deletedRows > 1 {
		return zerrors.ThrowInternalf(nil, ErrMoreThanOneRowAffected, "expected 1 session to be deleted, got %d", deletedRows)
	}

	cmd.DeletedAt = deletedAt
	cmd.deletedRows = deletedRows
	return nil
}

// String implements [Commander].
func (*DeleteSessionCommand) String() string {
	return "DeleteSessionCommand"
}

// Validate implements [Commander].
func (cmd *DeleteSessionCommand) Validate(ctx context.Context, opts *InvokeOpts) (err error) {
	if cmd.ID = strings.TrimSpace(cmd.ID); cmd.ID == "" {
		return zerrors.ThrowInvalidArgument(nil, ErrIDMissing, "Errors.IDMissing")
	}
	return nil
}

var (
	_ Commander     = (*DeleteSessionCommand)(nil)
	_ Transactional = (*DeleteSessionCommand)(nil)
)