// Copyright (c) 2025 Probo Inc <hello@getprobo.com>.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

package authz

import (
	"context"
	"errors"
	"fmt"
	"net/url"
	"time"

	"github.com/getprobo/probo/packages/emails"
	"github.com/getprobo/probo/pkg/coredata"
	"github.com/getprobo/probo/pkg/gid"
	"github.com/getprobo/probo/pkg/page"
	"github.com/getprobo/probo/pkg/statelesstoken"
	"go.gearno.de/kit/pg"
)

type (
	// Service handles all authorization logic including organization
	// membership and permissions. This service is completely independent
	// of authentication methods.
	Service struct {
		pg                      *pg.Client
		hostname                string
		tokenSecret             string
		invitationTokenValidity time.Duration
	}

	TenantAuthzService struct {
		pg                      *pg.Client
		hostname                string
		tokenSecret             string
		invitationTokenValidity time.Duration
		scope                   coredata.Scoper
	}

	Role string
)

const (
	RoleOwner  Role = "OWNER"
	RoleAdmin  Role = "ADMIN"
	RoleMember Role = "MEMBER"
	RoleViewer Role = "VIEWER"
)

const (
	TokenTypeOrganizationInvitation = "organization_invitation"
)

func NewService(
	ctx context.Context,
	pgClient *pg.Client,
	hostname string,
	tokenSecret string,
	invitationTokenValidity time.Duration,
) (*Service, error) {
	return &Service{
		pg:                      pgClient,
		hostname:                hostname,
		tokenSecret:             tokenSecret,
		invitationTokenValidity: invitationTokenValidity,
	}, nil
}

func (s *Service) WithTenant(tenantID gid.TenantID) *TenantAuthzService {
	return &TenantAuthzService{
		pg:                      s.pg,
		hostname:                s.hostname,
		tokenSecret:             s.tokenSecret,
		invitationTokenValidity: s.invitationTokenValidity,
		scope:                   coredata.NewScope(tenantID),
	}
}

// This method is on Service (not TenantAuthzService) because it operates across tenants
// and doesn't require tenant-scoped access.
func (s *Service) GetAllUserOrganizations(
	ctx context.Context,
	userID gid.GID,
) ([]*coredata.Organization, error) {
	var organizations []*coredata.Organization

	err := s.pg.WithConn(ctx, func(conn pg.Conn) error {
		var organizationList coredata.Organizations
		if err := organizationList.LoadAllByUserID(ctx, conn, userID); err != nil {
			return fmt.Errorf("failed to load user organizations: %w", err)
		}

		organizations = organizationList

		return nil
	})

	return organizations, err
}

// This method is on Service (not TenantAuthzService) because it operates across tenants
// and doesn't require tenant-scoped access.
func (s *Service) GetUserOrganizations(
	ctx context.Context,
	userID gid.GID,
	cursor *page.Cursor[coredata.OrganizationOrderField],
) ([]*coredata.Organization, error) {
	var organizations coredata.Organizations

	err := s.pg.WithConn(ctx, func(conn pg.Conn) error {
		if err := organizations.LoadByUserID(ctx, conn, userID, cursor); err != nil {
			return fmt.Errorf("failed to load user organizations: %w", err)
		}
		return nil
	})

	return organizations, err
}

// This method is on Service (not TenantAuthzService) because the user accepting
// the invitation doesn't have tenant access yet.
func (s *Service) AcceptInvitation(
	ctx context.Context,
	token string,
	userID gid.GID,
) error {
	payload, err := statelesstoken.ValidateToken[coredata.InvitationData](
		s.tokenSecret,
		TokenTypeOrganizationInvitation,
		token,
	)
	if err != nil {
		return fmt.Errorf("invalid invitation token: %w", err)
	}
	invitationData := payload.Data
	scope := coredata.NewScope(invitationData.InvitationID.TenantID())

	return s.pg.WithTx(
		ctx,
		func(tx pg.Conn) error {
			invitation := &coredata.Invitation{}
			if err := invitation.LoadByID(ctx, tx, scope, invitationData.InvitationID); err != nil {
				var errInvitationNotFound *coredata.ErrInvitationNotFound
				if errors.As(err, &errInvitationNotFound) {
					return fmt.Errorf("invitation was deleted or no longer exists")
				}
				return fmt.Errorf("cannot load invitation: %w", err)
			}

			if invitation.AcceptedAt != nil {
				return fmt.Errorf("invitation already accepted")
			}

			if time.Now().After(invitation.ExpiresAt) {
				return fmt.Errorf("invitation expired")
			}

			now := time.Now()
			membershipID := gid.New(scope.GetTenantID(), coredata.MembershipEntityType)

			membership := &coredata.Membership{
				ID:             membershipID,
				UserID:         userID,
				OrganizationID: invitation.OrganizationID,
				Role:           invitation.Role,
				CreatedAt:      now,
				UpdatedAt:      now,
			}

			if err := membership.Create(ctx, tx, scope); err != nil {
				return fmt.Errorf("failed to add user to organization: %w", err)
			}

			invitation.AcceptedAt = &now
			if err := invitation.Update(ctx, tx, scope); err != nil {
				return fmt.Errorf("failed to mark invitation as accepted: %w", err)
			}

			return nil
		},
	)
}

// This method is on Service (not TenantAuthzService) because the user accepting
// the invitation doesn't have tenant access yet.
func (s *Service) AcceptInvitationByID(
	ctx context.Context,
	invitationID gid.GID,
	userID gid.GID,
) (*coredata.Invitation, error) {
	var acceptedInvitation *coredata.Invitation
	scope := coredata.NewScope(invitationID.TenantID())
	err := s.pg.WithTx(
		ctx,
		func(tx pg.Conn) error {
			invitation := &coredata.Invitation{}
			if err := invitation.LoadByID(ctx, tx, scope, invitationID); err != nil {
				var errInvitationNotFound *coredata.ErrInvitationNotFound
				if errors.As(err, &errInvitationNotFound) {
					return fmt.Errorf("invitation was deleted or no longer exists")
				}
				return fmt.Errorf("cannot load invitation: %w", err)
			}

			if invitation.AcceptedAt != nil {
				return fmt.Errorf("invitation already accepted")
			}

			if time.Now().After(invitation.ExpiresAt) {
				return fmt.Errorf("invitation expired")
			}

			user := &coredata.User{}
			if err := user.LoadByID(ctx, tx, userID); err != nil {
				return fmt.Errorf("cannot load user: %w", err)
			}

			if invitation.Email != user.EmailAddress {
				return fmt.Errorf("invitation email does not match user email")
			}

			now := time.Now()
			membershipID := gid.New(scope.GetTenantID(), coredata.MembershipEntityType)

			membership := &coredata.Membership{
				ID:             membershipID,
				UserID:         userID,
				OrganizationID: invitation.OrganizationID,
				Role:           invitation.Role,
				CreatedAt:      now,
				UpdatedAt:      now,
			}

			if err := membership.Create(ctx, tx, scope); err != nil {
				return fmt.Errorf("failed to add user to organization: %w", err)
			}

			invitation.AcceptedAt = &now
			if err := invitation.Update(ctx, tx, scope); err != nil {
				return fmt.Errorf("failed to mark invitation as accepted: %w", err)
			}

			acceptedInvitation = invitation
			return nil
		},
	)
	if err != nil {
		return nil, err
	}
	return acceptedInvitation, nil
}

// This method is on Service (not TenantAuthzService) because the user viewing
// their invitations doesn't have tenant access yet, and it operates across multiple tenants.
func (s *Service) GetUserInvitations(
	ctx context.Context,
	email string,
	cursor *page.Cursor[coredata.InvitationOrderField],
	filter *coredata.InvitationFilter,
) (*page.Page[*coredata.Invitation, coredata.InvitationOrderField], error) {
	var invitations coredata.Invitations

	err := s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			if err := invitations.LoadByEmail(ctx, conn, email, cursor, filter); err != nil {
				return fmt.Errorf("failed to load invitations: %w", err)
			}

			return nil
		},
	)
	if err != nil {
		return nil, err
	}

	return page.NewPage(invitations, cursor), nil
}

// This method is on Service (not TenantAuthzService) because the user viewing
// their invitations doesn't have tenant access yet, and it operates across multiple tenants.
func (s *Service) CountUserInvitations(
	ctx context.Context,
	email string,
	filter *coredata.InvitationFilter,
) (int, error) {
	var count int

	err := s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			var invitations coredata.Invitations
			var err error
			count, err = invitations.CountByEmail(ctx, conn, email, filter)
			return err
		},
	)

	return count, err
}

// This method is on Service (not TenantAuthzService) because the user viewing
// the invitation organization doesn't have tenant access yet.
func (s *Service) GetOrganizationByInvitationID(
	ctx context.Context,
	invitationID gid.GID,
) (*coredata.Organization, error) {
	scope := coredata.NewScope(invitationID.TenantID())

	var organization coredata.Organization
	err := s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			var invitation coredata.Invitation
			if err := invitation.LoadByID(ctx, conn, scope, invitationID); err != nil {
				return fmt.Errorf("failed to load invitation: %w", err)
			}

			if err := organization.LoadByID(ctx, conn, scope, invitation.OrganizationID); err != nil {
				return fmt.Errorf("failed to load organization: %w", err)
			}

			return nil
		},
	)
	if err != nil {
		return nil, err
	}

	return &organization, nil
}

// This method is on Service (not TenantAuthzService) because the user added to the organization
// doesn't have tenant access yet
func (s *Service) AddUserToOrganization(
	ctx context.Context,
	userID gid.GID,
	orgID gid.GID,
	role string,
) error {
	now := time.Now()
	tenantID := orgID.TenantID()
	membershipID := gid.New(tenantID, coredata.MembershipEntityType)
	scope := coredata.NewScope(tenantID)

	membership := &coredata.Membership{
		ID:             membershipID,
		UserID:         userID,
		OrganizationID: orgID,
		Role:           role,
		CreatedAt:      now,
		UpdatedAt:      now,
	}

	return s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			if err := membership.Create(ctx, conn, scope); err != nil {
				return fmt.Errorf("failed to add user to organization: %w", err)
			}
			return nil
		},
	)
}

func (s *TenantAuthzService) GetInvitationsByOrganizationID(
	ctx context.Context,
	orgID gid.GID,
	cursor *page.Cursor[coredata.InvitationOrderField],
	filter *coredata.InvitationFilter,
) (*page.Page[*coredata.Invitation, coredata.InvitationOrderField], error) {
	var invitations coredata.Invitations

	err := s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			if err := invitations.LoadByOrganizationID(ctx, conn, s.scope, orgID, cursor, filter); err != nil {
				return fmt.Errorf("failed to load organization invitations: %w", err)
			}

			return nil
		},
	)
	if err != nil {
		return nil, err
	}

	return page.NewPage(invitations, cursor), nil
}

func (s *TenantAuthzService) CountOrganizationInvitations(
	ctx context.Context,
	orgID gid.GID,
	filter *coredata.InvitationFilter,
) (int, error) {
	var count int
	err := s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			var invitations coredata.Invitations
			var err error
			count, err = invitations.CountByOrganizationID(ctx, conn, s.scope, orgID, filter)
			return err
		},
	)
	if err != nil {
		return 0, fmt.Errorf("failed to count invitations: %w", err)
	}

	return count, nil
}

func (s *TenantAuthzService) GetInvitationByID(
	ctx context.Context,
	invitationID gid.GID,
) (*coredata.Invitation, error) {
	invitation := &coredata.Invitation{}
	err := s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			if err := invitation.LoadByID(ctx, conn, s.scope, invitationID); err != nil {
				return fmt.Errorf("failed to load invitation: %w", err)
			}
			return nil
		},
	)
	if err != nil {
		return nil, err
	}
	return invitation, nil
}

func (s *TenantAuthzService) DeleteInvitation(
	ctx context.Context,
	invitationID gid.GID,
) error {
	return s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			invitation := &coredata.Invitation{}
			if err := invitation.LoadByID(ctx, conn, s.scope, invitationID); err != nil {
				return fmt.Errorf("failed to load invitation: %w", err)
			}

			if err := invitation.Delete(ctx, conn, s.scope); err != nil {
				return fmt.Errorf("failed to delete invitation: %w", err)
			}

			return nil
		},
	)
}

func (s *TenantAuthzService) GetMembershipsByOrganizationID(
	ctx context.Context,
	orgID gid.GID,
	cursor *page.Cursor[coredata.MembershipOrderField],
) (*page.Page[*coredata.Membership, coredata.MembershipOrderField], error) {
	var memberships coredata.Memberships

	err := s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			if err := memberships.LoadByOrganizationID(ctx, conn, s.scope, orgID, cursor); err != nil {
				return fmt.Errorf("failed to load organization memberships: %w", err)
			}

			return nil
		},
	)
	if err != nil {
		return nil, err
	}

	return page.NewPage(memberships, cursor), nil
}

func (s *TenantAuthzService) CountOrganizationMemberships(
	ctx context.Context,
	orgID gid.GID,
) (int, error) {
	var count int
	err := s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			var memberships coredata.Memberships
			var err error
			count, err = memberships.CountByOrganizationID(ctx, conn, s.scope, orgID)
			return err
		},
	)
	if err != nil {
		return 0, fmt.Errorf("failed to count memberships: %w", err)
	}

	return count, nil
}

func (s *TenantAuthzService) CountOrganizationUsers(
	ctx context.Context,
	orgID gid.GID,
) (int, error) {
	var count int
	err := s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			var users coredata.Users
			var err error
			count, err = users.CountByOrganizationID(ctx, conn, s.scope, orgID)
			return err
		},
	)
	if err != nil {
		return 0, fmt.Errorf("failed to count users: %w", err)
	}

	return count, nil
}

func (s *TenantAuthzService) CanUserAccessOrganization(
	ctx context.Context,
	userID gid.GID,
	orgID gid.GID,
) (bool, error) {
	membership := &coredata.Membership{}

	haveAccess := false

	err := s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			if err := membership.LoadByUserAndOrg(ctx, conn, s.scope, userID, orgID); err != nil {
				if _, ok := err.(coredata.ErrMembershipNotFound); ok {
					return nil // Not an error, just no access
				}
				return fmt.Errorf("failed to check organization access: %w", err)
			}
			haveAccess = true
			return nil
		},
	)

	if err != nil {
		return false, err
	}

	return haveAccess, nil
}

func (s *TenantAuthzService) GetUserRoleInOrganization(
	ctx context.Context,
	userID gid.GID,
	orgID gid.GID,
) (string, error) {
	membership := &coredata.Membership{}

	err := s.pg.WithConn(
		ctx,
		func(conn pg.Conn) error {
			if err := membership.LoadByUserAndOrg(ctx, conn, s.scope, userID, orgID); err != nil {
				return fmt.Errorf("failed to get user role: %w", err)
			}
			return nil
		},
	)

	if err != nil {
		return "", err
	}

	return membership.Role, nil
}

func (s *TenantAuthzService) RemoveMemberFromOrganization(
	ctx context.Context,
	orgID gid.GID,
	memberID gid.GID,
) error {
	membership := &coredata.Membership{}

	return s.pg.WithTx(
		ctx,
		func(tx pg.Conn) error {
			if err := membership.LoadByID(ctx, tx, s.scope, memberID); err != nil {
				return fmt.Errorf("failed to load membership: %w", err)
			}

			if membership.OrganizationID != orgID {
				return fmt.Errorf("membership does not belong to organization")
			}

			if err := membership.Delete(ctx, tx, s.scope); err != nil {
				return fmt.Errorf("failed to delete membership: %w", err)
			}

			return nil
		},
	)
}

func (s *TenantAuthzService) UpdateUserRole(
	ctx context.Context,
	userID gid.GID,
	orgID gid.GID,
	newRole string,
) error {
	return s.pg.WithTx(
		ctx,
		func(tx pg.Conn) error {
			membership := &coredata.Membership{}
			if err := membership.LoadByUserAndOrg(ctx, tx, s.scope, userID, orgID); err != nil {
				return fmt.Errorf("failed to find membership: %w", err)
			}

			membership.Role = newRole
			membership.UpdatedAt = time.Now()

			if err := membership.Update(ctx, tx, s.scope); err != nil {
				return fmt.Errorf("failed to update user role: %w", err)
			}

			return nil
		},
	)
}

func (s *TenantAuthzService) InviteUserToOrganization(
	ctx context.Context,
	organizationID gid.GID,
	emailAddress string,
	fullName string,
	role string,
) (*coredata.Invitation, error) {
	var invitation *coredata.Invitation

	err := s.pg.WithTx(ctx, func(tx pg.Conn) error {
		user := &coredata.User{}
		userExists := true
		if err := user.LoadByEmail(ctx, tx, emailAddress); err != nil {
			var userNotFound *coredata.ErrUserNotFound
			if errors.As(err, &userNotFound) {
				userExists = false
			} else {
				return fmt.Errorf("failed to check if user exists: %w", err)
			}
		}

		organization := &coredata.Organization{}
		if err := organization.LoadByID(ctx, tx, s.scope, organizationID); err != nil {
			return fmt.Errorf("failed to load organization: %w", err)
		}

		invitationID := gid.New(s.scope.GetTenantID(), coredata.InvitationEntityType)
		now := time.Now()
		invitation = &coredata.Invitation{
			ID:             invitationID,
			OrganizationID: organizationID,
			Email:          emailAddress,
			FullName:       fullName,
			Role:           role,
			ExpiresAt:      now.Add(s.invitationTokenValidity),
			CreatedAt:      now,
		}

		var err error
		var invitationURL string
		var recipientName string

		if userExists {
			recipientName = user.FullName
			invitationURL = fmt.Sprintf("https://%s/", s.hostname)
		} else {
			recipientName = fullName
			invitationData := coredata.InvitationData{
				InvitationID:   invitationID,
				OrganizationID: organizationID,
				Email:          emailAddress,
				FullName:       fullName,
				Role:           role,
			}

			invitationToken, err := statelesstoken.NewToken(
				s.tokenSecret,
				TokenTypeOrganizationInvitation,
				s.invitationTokenValidity,
				invitationData,
			)
			if err != nil {
				return fmt.Errorf("failed to generate invitation token: %w", err)
			}

			invitationURL = fmt.Sprintf("https://%s/auth/signup-from-invitation?token=%s&fullName=%s", s.hostname, invitationToken, url.QueryEscape(fullName))
		}

		subject, textBody, htmlBody, err := emails.RenderInvitation(
			s.hostname,
			recipientName,
			organization.Name,
			invitationURL,
		)
		if err != nil {
			return fmt.Errorf("failed to render invitation email: %w", err)
		}

		email := coredata.NewEmail(
			fullName,
			emailAddress,
			subject,
			textBody,
			htmlBody,
		)

		if err := email.Insert(ctx, tx); err != nil {
			return fmt.Errorf("cannot insert email: %w", err)
		}

		if err := invitation.Create(ctx, tx, s.scope); err != nil {
			return fmt.Errorf("cannot create invitation: %w", err)
		}

		return nil
	})

	if err != nil {
		return nil, err
	}

	return invitation, nil
}

// This is a placeholder for future permission system
func (s *TenantAuthzService) HasPermission(
	ctx context.Context,
	userID gid.GID,
	orgID gid.GID,
	resource string,
	action string,
) (bool, error) {
	// For now, just check if user is a member
	// In the future, this will check specific permissions based on role
	return s.CanUserAccessOrganization(ctx, userID, orgID)
}