package useCases

import (
	"RenewCMS/internal/domain/audit"
	"RenewCMS/internal/domain/contenttype"
	"RenewCMS/internal/domain/role"
	"RenewCMS/internal/domain/user"
	"context"
	"time"
)

type UpdateRoleUseCase struct {
	roles        role.Repository
	users        user.Repository
	contentTypes contenttype.Repository
	recorder     audit.Recorder
	now          func() time.Time
	viewer       roleViewer
}

type UpdateRoleCommand struct {
	Caller      ContentCaller
	ID          uint32
	Name        string
	Description string
	Grants      []role.Grant
	Version     uint32
}

type ResetRoleCommand struct {
	Caller  ContentCaller
	ID      uint32
	Version uint32
}

func NewUpdateRoleUseCase(roles role.Repository, users user.Repository, contentTypes contenttype.Repository, recorder audit.Recorder, now func() time.Time) *UpdateRoleUseCase {
	return &UpdateRoleUseCase{roles: roles, users: users, contentTypes: contentTypes, recorder: recorder, now: now, viewer: roleViewer{roles, users, contentTypes}}
}

func (u *UpdateRoleUseCase) Update(ctx context.Context, command UpdateRoleCommand) (RoleView, error) {
	target, err := u.roles.Get(command.ID)
	if err != nil {
		return RoleView{}, err
	}
	if err := u.checkTarget(command, target); err != nil {
		return RoleView{}, err
	}
	name, err := role.NormalizeName(command.Name)
	if err != nil {
		return RoleView{}, err
	}
	if err := validateRoleGrants(u.contentTypes, command.Grants); err != nil {
		return RoleView{}, err
	}
	after := target
	after.Name = name
	after.Description = command.Description
	after.Grants = normalizedGrants(command.Grants)
	if err := ensureCovered(command.Caller, u.contentTypes, after); err != nil {
		return RoleView{}, err
	}
	if err := ensureNameFree(u.roles, name, target.ID); err != nil {
		return RoleView{}, err
	}
	return u.write(ctx, command.Caller, target, after)
}

func (u *UpdateRoleUseCase) Reset(ctx context.Context, command ResetRoleCommand) (RoleView, error) {
	target, err := u.roles.Get(command.ID)
	if err != nil {
		return RoleView{}, err
	}
	if err := ensureEditable(target); err != nil {
		return RoleView{}, err
	}
	if !target.BuiltIn {
		return RoleView{}, role.ErrNotBuiltIn
	}
	if err := requireOwnerOnlyEditing(command.Caller); err != nil {
		return RoleView{}, err
	}
	if command.Version != target.Version {
		return RoleView{}, role.ErrRoleConflict
	}
	seeded, found := seededRole(target.Name)
	if !found {
		return RoleView{}, role.ErrNotBuiltIn
	}
	after := target
	after.Description = seeded.Description
	after.Grants = seeded.EffectiveGrants()
	return u.write(ctx, command.Caller, target, after)
}

func (u *UpdateRoleUseCase) checkTarget(command UpdateRoleCommand, target role.Role) error {
	if err := ensureEditable(target); err != nil {
		return err
	}
	if target.BuiltIn {
		if err := requireOwnerOnlyEditing(command.Caller); err != nil {
			return err
		}
		if renamesBuiltIn(command.Name, target) {
			return role.ErrBuiltInName
		}
	}
	if err := ensureNotOwnRole(u.roles, u.users, command.Caller, target); err != nil {
		return err
	}
	if err := ensureCovered(command.Caller, u.contentTypes, target); err != nil {
		return err
	}
	if command.Version != target.Version {
		return role.ErrRoleConflict
	}
	return nil
}

func (u *UpdateRoleUseCase) write(ctx context.Context, caller ContentCaller, before role.Role, after role.Role) (RoleView, error) {
	members, err := u.viewer.members(before.ID)
	if err != nil {
		return RoleView{}, err
	}
	live, err := u.viewer.liveGrants(before.EffectiveGrants())
	if err != nil {
		return RoleView{}, err
	}
	diff := role.DiffGrants(live, after.Grants)
	if diff.Empty() && before.Name == after.Name && before.Description == after.Description {
		return u.viewer.one(before, members)
	}

	event := audit.NewEvent(audit.ActionRoleEdit, audit.CategoryRoles)
	event.Target = roleTarget(before)
	editor := caller.UserID
	after.UpdatedAt = u.now().UTC()
	after.UpdatedBy = &editor
	saved, err := u.roles.Save(after)
	if err != nil {
		recordRoleWriteFailure(ctx, u.recorder, event, err)
		return RoleView{}, err
	}
	event.Target = roleTarget(saved)
	event.Params = grantsParams(diff, members)
	event.Changes = audit.AppendTextChange(event.Changes, audit.FieldName, before.Name, saved.Name)
	event.Changes = audit.AppendTextChange(event.Changes, audit.FieldDescription, before.Description, saved.Description)
	u.recorder.Record(ctx, event)
	return u.viewer.one(saved, members)
}

func requireOwnerOnlyEditing(caller ContentCaller) error {
	if !caller.Grants.Holds(role.KeyRolesEditOwnerOnly) {
		return role.MissingPermissionError{Key: role.KeyRolesEditOwnerOnly}
	}
	return nil
}

func renamesBuiltIn(requested string, target role.Role) bool {
	trimmed, err := role.NormalizeName(requested)
	return err != nil || trimmed != target.Name
}

func seededRole(name string) (role.Role, bool) {
	for _, seeded := range role.BuiltInRoles() {
		if seeded.Name == name {
			return seeded, true
		}
	}
	return role.Role{}, false
}