package useCases

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

type ChangeUserRoleUseCase struct {
	users        user.Repository
	roles        role.Repository
	contentTypes contenttype.Repository
	recorder     audit.Recorder
}

type ChangeUserRoleCommand struct {
	Caller   ContentCaller
	TargetID uint32
	RoleID   uint32
}

func NewChangeUserRoleUseCase(users user.Repository, roles role.Repository, contentTypes contenttype.Repository, recorder audit.Recorder) *ChangeUserRoleUseCase {
	return &ChangeUserRoleUseCase{users: users, roles: roles, contentTypes: contentTypes, recorder: recorder}
}

var roleChangeRefusals = []error{user.ErrRoleChanged, user.ErrUserNotFound, role.ErrRoleNotFound, role.ErrUnknownRole}

func (u *ChangeUserRoleUseCase) ChangeRole(ctx context.Context, command ChangeUserRoleCommand) (DirectoryEntry, error) {
	target, err := u.users.Get(command.TargetID)
	if err != nil {
		return DirectoryEntry{}, err
	}
	current, held, err := u.heldRole(target)
	if err != nil {
		return DirectoryEntry{}, err
	}
	if held && current.Locked {
		return DirectoryEntry{}, role.ErrRoleLocked
	}
	next, err := assignableRole(u.roles, command.RoleID)
	if err != nil {
		return DirectoryEntry{}, err
	}
	if err := u.checkCoverage(command, target, current, held, next); err != nil {
		return DirectoryEntry{}, err
	}
	if held && current.ID == next.ID {
		ref := NewRoleRef(next)
		return userEntry(target, &ref), nil
	}
	return u.write(ctx, target, current, next)
}

func (u *ChangeUserRoleUseCase) heldRole(target user.User) (role.Role, bool, error) {
	current, err := resolveRole(u.roles, target)
	if errors.Is(err, role.ErrRoleNotFound) {
		return role.Role{}, false, nil
	}
	if err != nil {
		return role.Role{}, false, err
	}
	return current, true, nil
}

func (u *ChangeUserRoleUseCase) checkCoverage(command ChangeUserRoleCommand, target user.User, current role.Role, held bool, next role.Role) error {
	if target.ID == command.Caller.UserID {
		return role.ErrOwnRole
	}
	typeKeys, err := allowedTypeKeys(u.contentTypes)
	if err != nil {
		return err
	}
	if held {
		if err := ensureCoveredBy(command.Caller, typeKeys, current); err != nil {
			return err
		}
	}
	return ensureCoveredBy(command.Caller, typeKeys, next)
}

func (u *ChangeUserRoleUseCase) write(ctx context.Context, target user.User, current role.Role, next role.Role) (DirectoryEntry, error) {
	event := audit.NewEvent(audit.ActionUserChangeRole, audit.CategoryUsers)
	event.Target = audit.NewTarget(audit.TargetUser, target.ID, target.Username)
	updated, err := u.users.UpdateRole(target.ID, target.RoleID, next.ID)
	if errors.Is(err, role.ErrRoleNotFound) {
		return DirectoryEntry{}, role.ErrUnknownRole
	}
	if err != nil {
		u.recordWriteFailure(ctx, event, err)
		return DirectoryEntry{}, err
	}
	event.Params[audit.ParamFrom] = current.ID
	event.Params[audit.ParamTo] = next.ID
	event.Changes = audit.AppendTextChange(event.Changes, audit.FieldRole, current.Name, next.Name)
	u.recorder.Record(ctx, event)
	ref := NewRoleRef(next)
	return userEntry(updated, &ref), nil
}

func (u *ChangeUserRoleUseCase) recordWriteFailure(ctx context.Context, event audit.Event, err error) {
	for _, refusal := range roleChangeRefusals {
		if errors.Is(err, refusal) {
			return
		}
	}
	recordFailure(ctx, u.recorder, event, err)
}