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

package v3

import (
	"github.com/pb33f/libopenapi/datamodel/high"
	low "github.com/pb33f/libopenapi/datamodel/low/v3"
	"gopkg.in/yaml.v3"
	"sort"
)

// Paths represents a high-level OpenAPI 3+ Paths object, that is backed by a low-level one.
//
// Holds the relative paths to the individual endpoints and their operations. The path is appended to the URL from the
// Server Object in order to construct the full URL. The Paths MAY be empty, due to Access Control List (ACL)
// constraints.
//  - https://spec.openapis.org/oas/v3.1.0#paths-object
type Paths struct {
	PathItems  map[string]*PathItem `json:"-" yaml:"-"`
	Extensions map[string]any       `json:"-" yaml:"-"`
	low        *low.Paths
}

// NewPaths creates a new high-level instance of Paths from a low-level one.
func NewPaths(paths *low.Paths) *Paths {
	p := new(Paths)
	p.low = paths
	p.Extensions = high.ExtractExtensions(paths.Extensions)
	items := make(map[string]*PathItem)

	// build paths async for speed.
	type pRes struct {
		k string
		v *PathItem
	}
	var buildPathItem = func(key string, item *low.PathItem, c chan<- pRes) {
		c <- pRes{key, NewPathItem(item)}
	}
	rChan := make(chan pRes)
	for k := range paths.PathItems {
		go buildPathItem(k.Value, paths.PathItems[k].Value, rChan)
	}
	pathsBuilt := 0
	for pathsBuilt < len(paths.PathItems) {
		select {
		case r := <-rChan:
			pathsBuilt++
			items[r.k] = r.v
		}
	}
	p.PathItems = items
	return p
}

// GoLow returns the low-level Paths instance used to create the high-level one.
func (p *Paths) GoLow() *low.Paths {
	return p.low
}

// GoLowUntyped will return the low-level Paths instance that was used to create the high-level one, with no type
func (p *Paths) GoLowUntyped() any {
	return p.low
}

// Render will return a YAML representation of the Paths object as a byte slice.
func (p *Paths) Render() ([]byte, error) {
	return yaml.Marshal(p)
}

// MarshalYAML will create a ready to render YAML representation of the Paths object.
func (p *Paths) MarshalYAML() (interface{}, error) {
	// map keys correctly.
	m := high.CreateEmptyMapNode()
	type pathItem struct {
		pi       *PathItem
		path     string
		line     int
		rendered *yaml.Node
	}
	var mapped []*pathItem

	for k, pi := range p.PathItems {
		ln := 9999 // default to a high value to weight new content to the bottom.
		if p.low != nil {
			lpi := p.low.FindPath(k)
			if lpi != nil {
				ln = lpi.ValueNode.Line
			}
		}
		mapped = append(mapped, &pathItem{pi, k, ln, nil})
	}

	nb := high.NewNodeBuilder(p, p.low)
	extNode := nb.Render()
	if extNode != nil && extNode.Content != nil {
		var label string
		for u := range extNode.Content {
			if u%2 == 0 {
				label = extNode.Content[u].Value
				continue
			}
			mapped = append(mapped, &pathItem{nil, label,
				extNode.Content[u].Line, extNode.Content[u]})
		}
	}

	sort.Slice(mapped, func(i, j int) bool {
		return mapped[i].line < mapped[j].line
	})
	for j := range mapped {
		if mapped[j].pi != nil {
			rendered, _ := mapped[j].pi.MarshalYAML()
			m.Content = append(m.Content, high.CreateStringNode(mapped[j].path))
			m.Content = append(m.Content, rendered.(*yaml.Node))
		}
		if mapped[j].rendered != nil {
			m.Content = append(m.Content, high.CreateStringNode(mapped[j].path))
			m.Content = append(m.Content, mapped[j].rendered)
		}
	}

	return m, nil
}