package openapi3

import (
	"context"
	"path/filepath"
	"strings"
)

type RefNameResolver func(string) string

// DefaultRefResolver is a default implementation of refNameResolver for the
// InternalizeRefs function.
//
// If a reference points to an element inside a document, it returns the last
// element in the reference using filepath.Base. Otherwise if the reference points
// to a file, it returns the file name trimmed of all extensions.
func DefaultRefNameResolver(ref string) string {
	if ref == "" {
		return ""
	}
	split := strings.SplitN(ref, "#", 2)
	if len(split) == 2 {
		return filepath.Base(split[1])
	}
	ref = split[0]
	for ext := filepath.Ext(ref); len(ext) > 0; ext = filepath.Ext(ref) {
		ref = strings.TrimSuffix(ref, ext)
	}
	return filepath.Base(ref)
}

func schemaNames(s Schemas) []string {
	out := make([]string, 0, len(s))
	for i := range s {
		out = append(out, i)
	}
	return out
}

func parametersMapNames(s ParametersMap) []string {
	out := make([]string, 0, len(s))
	for i := range s {
		out = append(out, i)
	}
	return out
}

func isExternalRef(ref string, parentIsExternal bool) bool {
	return ref != "" && (!strings.HasPrefix(ref, "#/components/") || parentIsExternal)
}

func (doc *T) addSchemaToSpec(s *SchemaRef, refNameResolver RefNameResolver, parentIsExternal bool) bool {
	if s == nil || !isExternalRef(s.Ref, parentIsExternal) {
		return false
	}

	name := refNameResolver(s.Ref)
	if doc.Components != nil {
		if _, ok := doc.Components.Schemas[name]; ok {
			s.Ref = "#/components/schemas/" + name
			return true
		}
	}

	if doc.Components == nil {
		doc.Components = &Components{}
	}
	if doc.Components.Schemas == nil {
		doc.Components.Schemas = make(Schemas)
	}
	doc.Components.Schemas[name] = s.Value.NewRef()
	s.Ref = "#/components/schemas/" + name
	return true
}

func (doc *T) addParameterToSpec(p *ParameterRef, refNameResolver RefNameResolver, parentIsExternal bool) bool {
	if p == nil || !isExternalRef(p.Ref, parentIsExternal) {
		return false
	}
	name := refNameResolver(p.Ref)
	if doc.Components != nil {
		if _, ok := doc.Components.Parameters[name]; ok {
			p.Ref = "#/components/parameters/" + name
			return true
		}
	}

	if doc.Components == nil {
		doc.Components = &Components{}
	}
	if doc.Components.Parameters == nil {
		doc.Components.Parameters = make(ParametersMap)
	}
	doc.Components.Parameters[name] = &ParameterRef{Value: p.Value}
	p.Ref = "#/components/parameters/" + name
	return true
}

func (doc *T) addHeaderToSpec(h *HeaderRef, refNameResolver RefNameResolver, parentIsExternal bool) bool {
	if h == nil || !isExternalRef(h.Ref, parentIsExternal) {
		return false
	}
	name := refNameResolver(h.Ref)
	if doc.Components != nil {
		if _, ok := doc.Components.Headers[name]; ok {
			h.Ref = "#/components/headers/" + name
			return true
		}
	}

	if doc.Components == nil {
		doc.Components = &Components{}
	}
	if doc.Components.Headers == nil {
		doc.Components.Headers = make(Headers)
	}
	doc.Components.Headers[name] = &HeaderRef{Value: h.Value}
	h.Ref = "#/components/headers/" + name
	return true
}

func (doc *T) addRequestBodyToSpec(r *RequestBodyRef, refNameResolver RefNameResolver, parentIsExternal bool) bool {
	if r == nil || !isExternalRef(r.Ref, parentIsExternal) {
		return false
	}
	name := refNameResolver(r.Ref)
	if doc.Components != nil {
		if _, ok := doc.Components.RequestBodies[name]; ok {
			r.Ref = "#/components/requestBodies/" + name
			return true
		}
	}

	if doc.Components == nil {
		doc.Components = &Components{}
	}
	if doc.Components.RequestBodies == nil {
		doc.Components.RequestBodies = make(RequestBodies)
	}
	doc.Components.RequestBodies[name] = &RequestBodyRef{Value: r.Value}
	r.Ref = "#/components/requestBodies/" + name
	return true
}

func (doc *T) addResponseToSpec(r *ResponseRef, refNameResolver RefNameResolver, parentIsExternal bool) bool {
	if r == nil || !isExternalRef(r.Ref, parentIsExternal) {
		return false
	}
	name := refNameResolver(r.Ref)
	if doc.Components != nil {
		if _, ok := doc.Components.Responses[name]; ok {
			r.Ref = "#/components/responses/" + name
			return true
		}
	}

	if doc.Components == nil {
		doc.Components = &Components{}
	}
	if doc.Components.Responses == nil {
		doc.Components.Responses = make(ResponseBodies)
	}
	doc.Components.Responses[name] = &ResponseRef{Value: r.Value}
	r.Ref = "#/components/responses/" + name
	return true
}

func (doc *T) addSecuritySchemeToSpec(ss *SecuritySchemeRef, refNameResolver RefNameResolver, parentIsExternal bool) {
	if ss == nil || !isExternalRef(ss.Ref, parentIsExternal) {
		return
	}
	name := refNameResolver(ss.Ref)
	if doc.Components != nil {
		if _, ok := doc.Components.SecuritySchemes[name]; ok {
			ss.Ref = "#/components/securitySchemes/" + name
			return
		}
	}

	if doc.Components == nil {
		doc.Components = &Components{}
	}
	if doc.Components.SecuritySchemes == nil {
		doc.Components.SecuritySchemes = make(SecuritySchemes)
	}
	doc.Components.SecuritySchemes[name] = &SecuritySchemeRef{Value: ss.Value}
	ss.Ref = "#/components/securitySchemes/" + name

}

func (doc *T) addExampleToSpec(e *ExampleRef, refNameResolver RefNameResolver, parentIsExternal bool) {
	if e == nil || !isExternalRef(e.Ref, parentIsExternal) {
		return
	}
	name := refNameResolver(e.Ref)
	if doc.Components != nil {
		if _, ok := doc.Components.Examples[name]; ok {
			e.Ref = "#/components/examples/" + name
			return
		}
	}

	if doc.Components == nil {
		doc.Components = &Components{}
	}
	if doc.Components.Examples == nil {
		doc.Components.Examples = make(Examples)
	}
	doc.Components.Examples[name] = &ExampleRef{Value: e.Value}
	e.Ref = "#/components/examples/" + name

}

func (doc *T) addLinkToSpec(l *LinkRef, refNameResolver RefNameResolver, parentIsExternal bool) {
	if l == nil || !isExternalRef(l.Ref, parentIsExternal) {
		return
	}
	name := refNameResolver(l.Ref)
	if doc.Components != nil {
		if _, ok := doc.Components.Links[name]; ok {
			l.Ref = "#/components/links/" + name
			return
		}
	}

	if doc.Components == nil {
		doc.Components = &Components{}
	}
	if doc.Components.Links == nil {
		doc.Components.Links = make(Links)
	}
	doc.Components.Links[name] = &LinkRef{Value: l.Value}
	l.Ref = "#/components/links/" + name

}

func (doc *T) addCallbackToSpec(c *CallbackRef, refNameResolver RefNameResolver, parentIsExternal bool) bool {
	if c == nil || !isExternalRef(c.Ref, parentIsExternal) {
		return false
	}
	name := refNameResolver(c.Ref)

	if doc.Components == nil {
		doc.Components = &Components{}
	}
	if doc.Components.Callbacks == nil {
		doc.Components.Callbacks = make(Callbacks)
	}
	c.Ref = "#/components/callbacks/" + name
	doc.Components.Callbacks[name] = &CallbackRef{Value: c.Value}
	return true
}

func (doc *T) derefSchema(s *Schema, refNameResolver RefNameResolver, parentIsExternal bool) {
	if s == nil || doc.isVisitedSchema(s) {
		return
	}

	for _, list := range []SchemaRefs{s.AllOf, s.AnyOf, s.OneOf} {
		for _, s2 := range list {
			isExternal := doc.addSchemaToSpec(s2, refNameResolver, parentIsExternal)
			if s2 != nil {
				doc.derefSchema(s2.Value, refNameResolver, isExternal || parentIsExternal)
			}
		}
	}
	for _, s2 := range s.Properties {
		isExternal := doc.addSchemaToSpec(s2, refNameResolver, parentIsExternal)
		if s2 != nil {
			doc.derefSchema(s2.Value, refNameResolver, isExternal || parentIsExternal)
		}
	}
	for _, ref := range []*SchemaRef{s.Not, s.AdditionalProperties.Schema, s.Items} {
		isExternal := doc.addSchemaToSpec(ref, refNameResolver, parentIsExternal)
		if ref != nil {
			doc.derefSchema(ref.Value, refNameResolver, isExternal || parentIsExternal)
		}
	}
}

func (doc *T) derefHeaders(hs Headers, refNameResolver RefNameResolver, parentIsExternal bool) {
	for _, h := range hs {
		isExternal := doc.addHeaderToSpec(h, refNameResolver, parentIsExternal)
		if doc.isVisitedHeader(h.Value) {
			continue
		}
		doc.derefParameter(h.Value.Parameter, refNameResolver, parentIsExternal || isExternal)
	}
}

func (doc *T) derefExamples(es Examples, refNameResolver RefNameResolver, parentIsExternal bool) {
	for _, e := range es {
		doc.addExampleToSpec(e, refNameResolver, parentIsExternal)
	}
}

func (doc *T) derefContent(c Content, refNameResolver RefNameResolver, parentIsExternal bool) {
	for _, mediatype := range c {
		isExternal := doc.addSchemaToSpec(mediatype.Schema, refNameResolver, parentIsExternal)
		if mediatype.Schema != nil {
			doc.derefSchema(mediatype.Schema.Value, refNameResolver, isExternal || parentIsExternal)
		}
		doc.derefExamples(mediatype.Examples, refNameResolver, parentIsExternal)
		for _, e := range mediatype.Encoding {
			doc.derefHeaders(e.Headers, refNameResolver, parentIsExternal)
		}
	}
}

func (doc *T) derefLinks(ls Links, refNameResolver RefNameResolver, parentIsExternal bool) {
	for _, l := range ls {
		doc.addLinkToSpec(l, refNameResolver, parentIsExternal)
	}
}

func (doc *T) derefResponse(r *ResponseRef, refNameResolver RefNameResolver, parentIsExternal bool) {
	isExternal := doc.addResponseToSpec(r, refNameResolver, parentIsExternal)
	if v := r.Value; v != nil {
		doc.derefHeaders(v.Headers, refNameResolver, isExternal || parentIsExternal)
		doc.derefContent(v.Content, refNameResolver, isExternal || parentIsExternal)
		doc.derefLinks(v.Links, refNameResolver, isExternal || parentIsExternal)
	}
}

func (doc *T) derefResponses(rs *Responses, refNameResolver RefNameResolver, parentIsExternal bool) {
	doc.derefResponseBodies(rs.Map(), refNameResolver, parentIsExternal)
}

func (doc *T) derefResponseBodies(es ResponseBodies, refNameResolver RefNameResolver, parentIsExternal bool) {
	for _, e := range es {
		doc.derefResponse(e, refNameResolver, parentIsExternal)
	}
}

func (doc *T) derefParameter(p Parameter, refNameResolver RefNameResolver, parentIsExternal bool) {
	isExternal := doc.addSchemaToSpec(p.Schema, refNameResolver, parentIsExternal)
	doc.derefContent(p.Content, refNameResolver, parentIsExternal)
	if p.Schema != nil {
		doc.derefSchema(p.Schema.Value, refNameResolver, isExternal || parentIsExternal)
	}
}

func (doc *T) derefRequestBody(r RequestBody, refNameResolver RefNameResolver, parentIsExternal bool) {
	doc.derefContent(r.Content, refNameResolver, parentIsExternal)
}

func (doc *T) derefPaths(paths map[string]*PathItem, refNameResolver RefNameResolver, parentIsExternal bool) {
	for _, ops := range paths {
		pathIsExternal := isExternalRef(ops.Ref, parentIsExternal)
		// inline full operations
		ops.Ref = ""

		for _, param := range ops.Parameters {
			doc.addParameterToSpec(param, refNameResolver, pathIsExternal)
		}

		for _, op := range ops.Operations() {
			isExternal := doc.addRequestBodyToSpec(op.RequestBody, refNameResolver, pathIsExternal)
			if op.RequestBody != nil && op.RequestBody.Value != nil {
				doc.derefRequestBody(*op.RequestBody.Value, refNameResolver, pathIsExternal || isExternal)
			}
			for _, cb := range op.Callbacks {
				isExternal := doc.addCallbackToSpec(cb, refNameResolver, pathIsExternal)
				if cb.Value != nil {
					cbValue := (*cb.Value).Map()
					doc.derefPaths(cbValue, refNameResolver, pathIsExternal || isExternal)
				}
			}
			doc.derefResponses(op.Responses, refNameResolver, pathIsExternal)
			for _, param := range op.Parameters {
				isExternal := doc.addParameterToSpec(param, refNameResolver, pathIsExternal)
				if param.Value != nil {
					doc.derefParameter(*param.Value, refNameResolver, pathIsExternal || isExternal)
				}
			}
		}
	}
}

// InternalizeRefs removes all references to external files from the spec and moves them
// to the components section.
//
// refNameResolver takes in references to returns a name to store the reference under locally.
// It MUST return a unique name for each reference type.
// A default implementation is provided that will suffice for most use cases. See the function
// documentation for more details.
//
// Example:
//
//	doc.InternalizeRefs(context.Background(), nil)
func (doc *T) InternalizeRefs(ctx context.Context, refNameResolver func(ref string) string) {
	doc.resetVisited()

	if refNameResolver == nil {
		refNameResolver = DefaultRefNameResolver
	}

	if components := doc.Components; components != nil {
		names := schemaNames(components.Schemas)
		for _, name := range names {
			schema := components.Schemas[name]
			isExternal := doc.addSchemaToSpec(schema, refNameResolver, false)
			if schema != nil {
				schema.Ref = "" // always dereference the top level
				doc.derefSchema(schema.Value, refNameResolver, isExternal)
			}
		}
		names = parametersMapNames(components.Parameters)
		for _, name := range names {
			p := components.Parameters[name]
			isExternal := doc.addParameterToSpec(p, refNameResolver, false)
			if p != nil && p.Value != nil {
				p.Ref = "" // always dereference the top level
				doc.derefParameter(*p.Value, refNameResolver, isExternal)
			}
		}
		doc.derefHeaders(components.Headers, refNameResolver, false)
		for _, req := range components.RequestBodies {
			isExternal := doc.addRequestBodyToSpec(req, refNameResolver, false)
			if req != nil && req.Value != nil {
				req.Ref = "" // always dereference the top level
				doc.derefRequestBody(*req.Value, refNameResolver, isExternal)
			}
		}
		doc.derefResponseBodies(components.Responses, refNameResolver, false)
		for _, ss := range components.SecuritySchemes {
			doc.addSecuritySchemeToSpec(ss, refNameResolver, false)
		}
		doc.derefExamples(components.Examples, refNameResolver, false)
		doc.derefLinks(components.Links, refNameResolver, false)
		for _, cb := range components.Callbacks {
			isExternal := doc.addCallbackToSpec(cb, refNameResolver, false)
			if cb != nil && cb.Value != nil {
				cb.Ref = "" // always dereference the top level
				cbValue := (*cb.Value).Map()
				doc.derefPaths(cbValue, refNameResolver, isExternal)
			}
		}
	}

	doc.derefPaths(doc.Paths.Map(), refNameResolver, false)
}
