package configkit

import (
	"encoding"
	"math"
	"reflect"
)

// secretCloneMode distinguishes fresh unresolved references from publication of
// already validated private state, which must not trigger another lookup.
type secretCloneMode uint8

const (
	cloneUnresolvedSecrets secretCloneMode = iota
	cloneValidatedSecrets
)

func cloneConfiguration(schema *schemaDescriptor, value reflect.Value, limits projectionLimits) (reflect.Value, *projectionIssue) {
	return cloneConfigurationWithMode(schema, value, limits, cloneUnresolvedSecrets)
}

func cloneConfigurationWithMode(schema *schemaDescriptor, value reflect.Value, limits projectionLimits, mode secretCloneMode) (reflect.Value, *projectionIssue) {
	if schema == nil || schema.root == nil || !value.IsValid() || value.Type() != schema.root.typeOf {
		return reflect.Value{}, &projectionIssue{code: CodeSchemaUnsupportedType, message: "configuration value does not match its schema"}
	}
	operation := valueOperation{schema: schema, limits: limits, active: make(map[valueVisit]bool), cloneMode: mode}
	return operation.clone(value, schema.root, Path{}, 0)
}

func (o *valueOperation) clone(value reflect.Value, descriptor *typeDescriptor, path Path, depth int) (reflect.Value, *projectionIssue) {
	if issue := o.checkDepth(path, depth); issue != nil {
		return reflect.Value{}, issue
	}
	if descriptor.kind == descriptorPointer {
		if value.IsNil() {
			return reflect.Zero(value.Type()), nil
		}
		leave, issue := o.enter(value, path)
		if issue != nil {
			return reflect.Value{}, issue
		}
		defer leave()
		child, issue := o.clone(value.Elem(), descriptor.element, path, depth)
		if issue != nil {
			return reflect.Value{}, issue
		}
		result := reflect.New(value.Type().Elem())
		result.Elem().Set(child)
		return result, nil
	}

	switch descriptor.kind {
	case descriptorStruct:
		result := reflect.New(value.Type()).Elem()
		for _, member := range descriptor.members {
			memberPath, memberDepth := path, depth
			if !member.inline {
				memberPath, memberDepth = path.Key(member.name), depth+1
			}
			cloned, issue := o.clone(value.Field(member.index), member.descriptor, memberPath, memberDepth)
			if issue != nil {
				return reflect.Value{}, issue
			}
			result.Field(member.index).Set(cloned)
		}
		return result, nil
	case descriptorMap:
		if value.IsNil() {
			return reflect.Zero(value.Type()), nil
		}
		leave, issue := o.enter(value, path)
		if issue != nil {
			return reflect.Value{}, issue
		}
		defer leave()
		result := reflect.MakeMapWithSize(value.Type(), value.Len())
		for _, key := range value.MapKeys() {
			cloned, issue := o.clone(value.MapIndex(key), descriptor.element, path.Key(key.String()), depth+1)
			if issue != nil {
				return reflect.Value{}, issue
			}
			result.SetMapIndex(key, cloned)
		}
		return result, nil
	case descriptorSlice:
		if value.IsNil() {
			return reflect.Zero(value.Type()), nil
		}
		leave, issue := o.enter(value, path)
		if issue != nil {
			return reflect.Value{}, issue
		}
		defer leave()
		result := reflect.MakeSlice(value.Type(), value.Len(), value.Len())
		for i := 0; i < value.Len(); i++ {
			cloned, issue := o.clone(value.Index(i), descriptor.element, path.Index(i), depth+1)
			if issue != nil {
				return reflect.Value{}, issue
			}
			result.Index(i).Set(cloned)
		}
		return result, nil
	case descriptorArray:
		result := reflect.New(value.Type()).Elem()
		for i := 0; i < value.Len(); i++ {
			cloned, issue := o.clone(value.Index(i), descriptor.element, path.Index(i), depth+1)
			if issue != nil {
				return reflect.Value{}, issue
			}
			result.Index(i).Set(cloned)
		}
		return result, nil
	case descriptorDynamic:
		if value.IsNil() {
			return reflect.Zero(value.Type()), nil
		}
		concrete := value.Elem()
		dynamic, issue := o.dynamicDescriptor(concrete.Type(), path)
		if issue != nil {
			return reflect.Value{}, issue
		}
		cloned, issue := o.clone(concrete, dynamic, path, depth)
		if issue != nil {
			return reflect.Value{}, issue
		}
		result := reflect.New(value.Type()).Elem()
		result.Set(cloned)
		return result, nil
	case descriptorSecret:
		result := reflect.New(value.Type()).Elem()
		reference := value.Interface().(Secret)
		if o.cloneMode == cloneValidatedSecrets {
			result.Set(value)
		} else if reference.specified {
			result.Set(reflect.ValueOf(SecretEnv(reference.EnvName())))
		}
		return result, nil
	case descriptorText:
		text, issue := marshalCanonicalText(value, path)
		if issue != nil {
			return reflect.Value{}, issue
		}
		result := reflect.New(value.Type()).Elem()
		unmarshaler := result.Addr().Interface().(encoding.TextUnmarshaler)
		if err := unmarshaler.UnmarshalText([]byte(text)); err != nil {
			return reflect.Value{}, &projectionIssue{code: CodeSchemaCodec, path: path.clone(), message: "custom text scalar could not be reconstructed"}
		}
		return result, nil
	case descriptorFloat:
		if math.IsNaN(value.Float()) || math.IsInf(value.Float(), 0) {
			return reflect.Value{}, &projectionIssue{code: CodeSchemaNonFinite, path: path.clone(), message: "configuration float must be finite"}
		}
		fallthrough
	default:
		result := reflect.New(value.Type()).Elem()
		result.Set(value)
		return result, nil
	}
}