#pragma once
#include <faset/core/json.hpp>
#include <faset/core/error.hpp>
#include <map>
#include <string>
#include <type_traits>

namespace faset::authoring {
class SchemaRegistry {
public:
    void register_schema(const Json& schema);
    void register_schemas(const Json& schemas);
    bool contains(const std::string& type) const;
    Json schema(const std::string& type) const;
    Json manifest() const;
    Json default_fields(const std::string& type) const;
    // Unknown fields and absent schemas survive authoring. Known fields are validated.
    void validate_component(const Json& component) const;
    Json migrate_component(const Json& component) const;
    void add_migration(const std::string& type, int from_version, Json field_rules);
private:
    std::map<std::string,Json> schemas_;
    std::map<std::pair<std::string,int>,Json> migrations_;
};

template<class T> class TypeRegistration {
public:
    TypeRegistration(SchemaRegistry& registry, std::string id, std::string name, int version=1)
        : registry_(registry),schema_{{"id",std::move(id)},{"name",std::move(name)},{"version",version},{"fields",Json::object()}} {}
    template<class Value>
    TypeRegistration& field(std::string id, std::string name, Value T::*member, Value default_value,
                            std::string kind, Json constraints=Json::object()) {
        static_assert(std::is_member_object_pointer_v<decltype(member)>);
        require(!schema_["fields"].contains(id),"schema.duplicate_field","Duplicate stable FieldId");
        // Converting the typed default checks supported JSON serialization at compile time.
        Json descriptor={{"id",id},{"name",std::move(name)},{"type",std::move(kind)},{"default",Json(default_value)}};
        descriptor.update(constraints); schema_["fields"][id]=std::move(descriptor); return *this;
    }
    void commit() { registry_.register_schema(schema_); }
private:
    SchemaRegistry& registry_;
    Json schema_;
};
SchemaRegistry builtin_schemas();
void validate_field(const Json& value,const Json& descriptor);
}