package low

import (
	"context"
	"fmt"
	"github.com/pb33f/libopenapi/index"
	"github.com/pb33f/libopenapi/utils"
	"gopkg.in/yaml.v3"
)

const (
	HASH = "%x"
)

type Reference struct {
	Reference string `json:"-" yaml:"-"`
}

func (r *Reference) GetReference() string {
	return r.Reference
}

func (r *Reference) IsReference() bool {
	return r.Reference != ""
}

func (r *Reference) SetReference(ref string) {
	r.Reference = ref
}

type IsReferenced interface {
	IsReference() bool
	GetReference() string
	SetReference(string)
}

// Buildable is an interface for any struct that can be 'built out'. This means that a struct can accept
// a root node and a reference to the index that carries data about any references used.
//
// Used by generic functions when automatically building out structs based on yaml.Node inputs.
type Buildable[T any] interface {
	Build(ctx context.Context, key, value *yaml.Node, idx *index.SpecIndex) error
	*T
}

// HasValueNode is implemented by NodeReference and ValueReference to return the yaml.Node backing the value.
type HasValueNode[T any] interface {
	GetValueNode() *yaml.Node
	*T
}

// HasValueNodeUntyped is implemented by NodeReference and ValueReference to return the yaml.Node backing the value.
type HasValueNodeUntyped interface {
	GetValueNode() *yaml.Node
	IsReferenced
}

// Hashable defines any struct that implements a Hash function that returns a 256SHA hash of the state of the
// representative object. Great for equality checking!
type Hashable interface {
	Hash() [32]byte
}

// HasExtensions is implemented by any object that exposes extensions
type HasExtensions[T any] interface {

	// GetExtensions returns generic low level extensions
	GetExtensions() map[KeyReference[string]]ValueReference[any]
}

// HasExtensionsUntyped is implemented by any object that exposes extensions
type HasExtensionsUntyped interface {

	// GetExtensions returns generic low level extensions
	GetExtensions() map[KeyReference[string]]ValueReference[any]
}

// HasValue is implemented by NodeReference and ValueReference to return the yaml.Node backing the value.
type HasValue[T any] interface {
	GetValue() T
	GetValueNode() *yaml.Node
	IsEmpty() bool
	*T
}

// HasValueUnTyped is implemented by NodeReference and ValueReference to return the yaml.Node backing the value.
type HasValueUnTyped interface {
	GetValueUntyped() any
	GetValueNode() *yaml.Node
}

// HasKeyNode is implemented by KeyReference to return the yaml.Node backing the key.
type HasKeyNode interface {
	GetKeyNode() *yaml.Node
}

// NodeReference is a low-level container for holding a Value of type T, as well as references to
// a key yaml.Node that points to the key node that contains the value node, and the value node that contains
// the actual value.
type NodeReference[T any] struct {

	// The value being referenced
	Value T

	// The yaml.Node that holds the value
	ValueNode *yaml.Node

	// The yaml.Node that is the key, that contains the value.
	KeyNode *yaml.Node

	// Is this value actually a reference in the original tree?
	ReferenceNode bool

	// If HasReference is true, then Reference contains the original $ref value.
	Reference string

	Context context.Context
}

// KeyReference is a low-level container for key nodes holding a Value of type T. A KeyNode is a pointer to the
// yaml.Node that holds a key to a value.
type KeyReference[T any] struct {

	// The value being referenced.
	Value T

	// The yaml.Node that holds this referenced key
	KeyNode *yaml.Node
}

// ValueReference is a low-level container for value nodes that hold a Value of type T. A ValueNode is a pointer
// to the yaml.Node that holds the value.
type ValueReference[T any] struct {

	// The value being referenced.
	Value T

	// The yaml.Node that holds the referenced value
	ValueNode *yaml.Node

	// Is this value actually a reference in the original tree?
	ReferenceNode bool

	// If HasReference is true, then Reference contains the original $ref value.
	Reference string
}

// IsEmpty will return true if this reference has no key or value nodes assigned (it's been ignored)
func (n NodeReference[T]) IsEmpty() bool {
	return n.KeyNode == nil && n.ValueNode == nil
}

func (n NodeReference[T]) NodeLineNumber() int {
	if !n.IsEmpty() {
		return n.ValueNode.Line
	} else {
		return 0
	}
}

func (n NodeReference[T]) GetReference() string {
	return n.Reference
}

func (n NodeReference[T]) SetReference(ref string) {
	n.Reference = ref
}

// IsReference will return true if the key node contains a $ref key.
func (n NodeReference[T]) IsReference() bool {
	if n.ReferenceNode {
		return true
	}
	if n.KeyNode != nil {
		for k := range n.KeyNode.Content {
			if k%2 == 0 {
				if n.KeyNode.Content[k].Value == "$ref" {
					n.ReferenceNode = true
					return true
				}
			}
		}
	}
	return false
}

// GenerateMapKey will return a string based on the line and column number of the node, e.g. 33:56 for line 33, col 56.
func (n NodeReference[T]) GenerateMapKey() string {
	return fmt.Sprintf("%d:%d", n.ValueNode.Line, n.ValueNode.Column)
}

// Mutate will set the reference value to what is supplied. This happens to both the Value and ValueNode, which means
// the root document is permanently mutated and changes will be reflected in any serialization of the root document.
func (n NodeReference[T]) Mutate(value T) NodeReference[T] {
	n.ValueNode.Value = fmt.Sprintf("%v", value)
	n.Value = value
	return n
}

// GetValueNode will return the yaml.Node containing the reference value node
func (n NodeReference[T]) GetValueNode() *yaml.Node {
	return n.ValueNode
}

// GetKeyNode will return the yaml.Node containing the reference key node
func (n NodeReference[T]) GetKeyNode() *yaml.Node {
	return n.KeyNode
}

// GetValue will return the  raw value of the node
func (n NodeReference[T]) GetValue() T {
	return n.Value
}

// GetValueUntyped will return the raw value of the node with no type
func (n NodeReference[T]) GetValueUntyped() any {
	return n.Value
}

// IsEmpty will return true if this reference has no key or value nodes assigned (it's been ignored)
func (n ValueReference[T]) IsEmpty() bool {
	return n.ValueNode == nil
}

// NodeLineNumber will return the line number of the value node (or 0 if the value node is empty)
func (n ValueReference[T]) NodeLineNumber() int {
	if !n.IsEmpty() {
		return n.ValueNode.Line
	} else {
		return 0
	}
}

// GenerateMapKey will return a string based on the line and column number of the node, e.g. 33:56 for line 33, col 56.
func (n ValueReference[T]) GenerateMapKey() string {
	return fmt.Sprintf("%d:%d", n.ValueNode.Line, n.ValueNode.Column)
}

// GetValueNode will return the yaml.Node containing the reference value node
func (n ValueReference[T]) GetValueNode() *yaml.Node {
	return n.ValueNode
}

// GetValue will return the  raw value of the node
func (n ValueReference[T]) GetValue() T {
	return n.Value
}

// GetValueUntyped will return the raw value of the node with no type
func (n ValueReference[T]) GetValueUntyped() any {
	return n.Value
}

func (n ValueReference[T]) GetReference() string {
	return n.Reference
}

func (n ValueReference[T]) SetReference(ref string) {
	n.Reference = ref
}

// IsReference will return true if the key node contains a $ref
func (n ValueReference[T]) IsReference() bool {
	if n.Reference != "" {
		return true
	}
	return false
}

func (n ValueReference[T]) MarshalYAML() (interface{}, error) {
	if n.IsReference() {
		nodes := make([]*yaml.Node, 2)
		nodes[0] = utils.CreateStringNode("$ref")
		nodes[1] = utils.CreateStringNode(n.Reference)
		m := utils.CreateEmptyMapNode()
		m.Content = nodes
		return m, nil
	}
	var h yaml.Node
	e := n.ValueNode.Decode(&h)
	return h, e
}

// IsEmpty will return true if this reference has no key or value nodes assigned (it's been ignored)
func (n KeyReference[T]) IsEmpty() bool {
	return n.KeyNode == nil
}

// GetValueUntyped will return the raw value of the node with no type
func (n KeyReference[T]) GetValueUntyped() any {
	return n.Value
}

// GetKeyNode will return the yaml.Node containing the reference key node.
func (n KeyReference[T]) GetKeyNode() *yaml.Node {
	return n.KeyNode
}

// GenerateMapKey will return a string based on the line and column number of the node, e.g. 33:56 for line 33, col 56.
func (n KeyReference[T]) GenerateMapKey() string {
	return fmt.Sprintf("%d:%d", n.KeyNode.Line, n.KeyNode.Column)
}

// Mutate will set the reference value to what is supplied. This happens to both the Value and ValueNode, which means
// the root document is permanently mutated and changes will be reflected in any serialization of the root document.
func (n ValueReference[T]) Mutate(value T) ValueReference[T] {
	n.ValueNode.Value = fmt.Sprintf("%v", value)
	n.Value = value
	return n
}

// IsCircular will determine if the node in question, is part of a circular reference chain discovered by the index.
func IsCircular(node *yaml.Node, idx *index.SpecIndex) bool {
	if idx == nil {
		return false // no index! nothing we can do.
	}
	refs := idx.GetCircularReferences()
	for i := range idx.GetCircularReferences() {
		if refs[i].LoopPoint.Node == node {
			return true
		}
		for k := range refs[i].Journey {
			if refs[i].Journey[k].Node == node {
				return true
			}
			isRef, _, refValue := utils.IsNodeRefValue(node)
			if isRef && refs[i].Journey[k].Definition == refValue {
				return true
			}
		}
	}
	// check mapped references in case we didn't find it.
	_, nv := utils.FindKeyNode("$ref", node.Content)
	if nv != nil {
		ref := idx.GetMappedReferences()[nv.Value]
		if ref != nil {
			return ref.Circular
		}
	}
	return false
}

// GetCircularReferenceResult will check if a node is part of a circular reference chain and then return that
// index.CircularReferenceResult it was located in. Returns nil if not found.
func GetCircularReferenceResult(node *yaml.Node, idx *index.SpecIndex) *index.CircularReferenceResult {
	if idx == nil {
		return nil // no index! nothing we can do.
	}
	refs := idx.GetCircularReferences()
	for i := range refs {
		if refs[i].LoopPoint.Node == node {
			return refs[i]
		}
		for k := range refs[i].Journey {
			if refs[i].Journey[k].Node == node {
				return refs[i]
			}
			isRef, _, refValue := utils.IsNodeRefValue(node)
			if isRef && refs[i].Journey[k].Definition == refValue {
				return refs[i]
			}
		}
	}
	// check mapped references in case we didn't find it.
	_, nv := utils.FindKeyNode("$ref", node.Content)
	if nv != nil {
		for i := range refs {
			if refs[i].LoopPoint.Definition == nv.Value {
				return refs[i]
			}
		}
	}
	return nil
}

func HashToString(hash [32]byte) string {
	return fmt.Sprintf("%x", hash)
}