// Copyright 2022-2026 Princess B33f Heavy Industries / Dave Shanley
// SPDX-License-Identifier: MIT

package base

import (
	"context"
	"hash/maphash"
	"sync"

	"github.com/pb33f/libopenapi/datamodel/low"
	"github.com/pb33f/libopenapi/index"
	"github.com/pb33f/libopenapi/orderedmap"
	"github.com/pb33f/libopenapi/utils"
	"go.yaml.in/yaml/v4"
)

// ExternalDoc represents a low-level External Documentation object as defined by OpenAPI 2 and 3
//
// Allows referencing an external resource for extended documentation.
//
//	v2 - https://swagger.io/specification/v2/#externalDocumentationObject
//	v3 - https://spec.openapis.org/oas/v3.1.0#external-documentation-object
type ExternalDoc struct {
	Description low.NodeReference[string]
	URL         low.NodeReference[string]
	Extensions  *orderedmap.Map[low.KeyReference[string], low.ValueReference[*yaml.Node]]
	KeyNode     *yaml.Node
	RootNode    *yaml.Node
	index       *index.SpecIndex
	context     context.Context
	nodeStore   sync.Map
	reference   low.Reference
	*low.Reference
	low.NodeMap
}

// FindExtension returns a ValueReference containing the extension value, if found.
func (ex *ExternalDoc) FindExtension(ext string) *low.ValueReference[*yaml.Node] {
	return low.FindItemInOrderedMap[*yaml.Node](ext, ex.Extensions)
}

// GetRootNode will return the root yaml node of the ExternalDoc object
func (ex *ExternalDoc) GetRootNode() *yaml.Node {
	return ex.RootNode
}

// GetKeyNode will return the key yaml node of the ExternalDoc object
func (ex *ExternalDoc) GetKeyNode() *yaml.Node {
	return ex.KeyNode
}

// Build will extract extensions from the ExternalDoc instance.
func (ex *ExternalDoc) Build(ctx context.Context, keyNode, root *yaml.Node, idx *index.SpecIndex) error {
	ex.KeyNode = keyNode
	ex.reference = low.Reference{}
	ex.Reference = &ex.reference
	ex.nodeStore = sync.Map{}
	ex.Nodes = &ex.nodeStore
	ex.context = ctx
	ex.index = idx
	if root == nil {
		ex.RootNode = nil
		ex.Extensions = nil
		return nil
	}
	root = utils.NodeAlias(root)
	ex.RootNode = root
	utils.CheckForMergeNodes(root)
	if len(root.Content) > 0 {
		ex.NodeMap.ExtractNodes(root, false)
	} else {
		ex.AddNode(root.Line, root)
	}
	ex.Extensions = low.ExtractExtensions(root)
	return nil
}

// GetExtensions returns all ExternalDoc extensions and satisfies the low.HasExtensions interface.
func (ex *ExternalDoc) GetExtensions() *orderedmap.Map[low.KeyReference[string], low.ValueReference[*yaml.Node]] {
	return ex.Extensions
}

func (ex *ExternalDoc) Hash() uint64 {
	return low.WithHasher(func(h *maphash.Hash) uint64 {
		if ex.Description.Value != "" {
			h.WriteString(ex.Description.Value)
			h.WriteByte(low.HASH_PIPE)
		}
		if ex.URL.Value != "" {
			h.WriteString(ex.URL.Value)
			h.WriteByte(low.HASH_PIPE)
		}
		for _, ext := range low.HashExtensions(ex.Extensions) {
			h.WriteString(ext)
			h.WriteByte(low.HASH_PIPE)
		}
		return h.Sum64()
	})
}

// GetIndex returns the index.SpecIndex instance attached to the ExternalDoc object
func (ex *ExternalDoc) GetIndex() *index.SpecIndex {
	return ex.index
}

// GetContext returns the context.Context instance used when building the ExternalDoc object
func (ex *ExternalDoc) GetContext() context.Context {
	return ex.context
}
