/*
Copyright 2015 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package generators

import (
	"fmt"
	"io"
	"path/filepath"
	"strings"

	"k8s.io/kubernetes/cmd/libs/go2idl/args"
	"k8s.io/kubernetes/cmd/libs/go2idl/generator"
	"k8s.io/kubernetes/cmd/libs/go2idl/namer"
	"k8s.io/kubernetes/cmd/libs/go2idl/types"
	"k8s.io/kubernetes/pkg/util/sets"

	"github.com/golang/glog"
)

// CustomArgs is used tby the go2idl framework to pass args specific to this
// generator.
type CustomArgs struct {
	BoundingDirs []string // Only deal with types rooted under these dirs.
}

// TODO: This is created only to reduce number of changes in a single PR.
// Remove it and use PublicNamer instead.
func deepCopyNamer() *namer.NameStrategy {
	return &namer.NameStrategy{
		Join: func(pre string, in []string, post string) string {
			return strings.Join(in, "_")
		},
		PrependPackageNames: 1,
	}
}

// NameSystems returns the name system used by the generators in this package.
func NameSystems() namer.NameSystems {
	return namer.NameSystems{
		"public": deepCopyNamer(),
		"raw":    namer.NewRawNamer("", nil),
	}
}

// DefaultNameSystem returns the default name system for ordering the types to be
// processed by the generators in this package.
func DefaultNameSystem() string {
	return "public"
}

func Packages(context *generator.Context, arguments *args.GeneratorArgs) generator.Packages {
	boilerplate, err := arguments.LoadGoBoilerplate()
	if err != nil {
		glog.Fatalf("Failed loading boilerplate: %v", err)
	}

	inputs := sets.NewString(arguments.InputDirs...)
	packages := generator.Packages{}
	header := append([]byte(fmt.Sprintf("// +build !%s\n\n", arguments.GeneratedBuildTag)), boilerplate...)
	header = append(header, []byte(
		`
// This file was autogenerated by deepcopy-gen. Do not edit it manually!

`)...)

	boundingDirs := []string{}
	if customArgs, ok := arguments.CustomArgs.(*CustomArgs); ok {
		for i := range customArgs.BoundingDirs {
			// Strip any trailing slashes - they are not exactly "correct" but
			// this is friendlier.
			boundingDirs = append(boundingDirs, strings.TrimRight(customArgs.BoundingDirs[i], "/"))
		}
	}

	for _, p := range context.Universe {
		copyableType := false
		for _, t := range p.Types {
			if copyableWithinPackage(t, boundingDirs) && inputs.Has(t.Name.Package) {
				copyableType = true
			}
		}
		if copyableType {
			path := p.Path
			packages = append(packages,
				&generator.DefaultPackage{
					PackageName: strings.Split(filepath.Base(path), ".")[0],
					PackagePath: path,
					HeaderText:  header,
					GeneratorFunc: func(c *generator.Context) (generators []generator.Generator) {
						generators = []generator.Generator{}
						generators = append(
							generators, NewGenDeepCopy("deep_copy_generated", path, boundingDirs, inputs.Has(path)))
						return generators
					},
					FilterFunc: func(c *generator.Context, t *types.Type) bool {
						return t.Name.Package == path
					},
				})
		}
	}
	return packages
}

const (
	apiPackagePath        = "k8s.io/kubernetes/pkg/api"
	conversionPackagePath = "k8s.io/kubernetes/pkg/conversion"
)

// genDeepCopy produces a file with autogenerated deep-copy functions.
type genDeepCopy struct {
	generator.DefaultGen
	targetPackage    string
	boundingDirs     []string
	imports          namer.ImportTracker
	typesForInit     []*types.Type
	generateInitFunc bool

	globalVariables map[string]interface{}
}

func NewGenDeepCopy(sanitizedName, targetPackage string, boundingDirs []string, generateInitFunc bool) generator.Generator {
	return &genDeepCopy{
		DefaultGen: generator.DefaultGen{
			OptionalName: sanitizedName,
		},
		targetPackage:    targetPackage,
		boundingDirs:     boundingDirs,
		imports:          generator.NewImportTracker(),
		typesForInit:     make([]*types.Type, 0),
		generateInitFunc: generateInitFunc,
	}
}

func (g *genDeepCopy) Namers(c *generator.Context) namer.NameSystems {
	// Have the raw namer for this file track what it imports.
	return namer.NameSystems{"raw": namer.NewRawNamer(g.targetPackage, g.imports)}
}

func (g *genDeepCopy) Filter(c *generator.Context, t *types.Type) bool {
	// Filter out all types not copyable within the package.
	copyable := g.copyableWithinPackage(t)
	if copyable {
		g.typesForInit = append(g.typesForInit, t)
	}
	return copyable
}

func (g *genDeepCopy) copyableWithinPackage(t *types.Type) bool {
	return copyableWithinPackage(t, g.boundingDirs)
}

// hasDeepCopyMethod returns true if an appropriate DeepCopy() method is
// defined for the given type.  This allows more efficient deep copy
// implementations to be defined by the type's author.  The correct signature
// for a type T is:
//    func (t T) DeepCopy() T
// or:
//    func (t *T) DeepCopyt() T
func hasDeepCopyMethod(t *types.Type) bool {
	for mn, mt := range t.Methods {
		if mn != "DeepCopy" {
			continue
		}
		if len(mt.Signature.Parameters) != 0 {
			return false
		}
		if len(mt.Signature.Results) != 1 || mt.Signature.Results[0].Name != t.Name {
			return false
		}
		return true
	}
	return false
}

func isRootedUnder(pkg string, roots []string) bool {
	// Add trailing / to avoid false matches, e.g. foo/bar vs foo/barn.  This
	// assumes that bounding dirs do not have trailing slashes.
	pkg = pkg + "/"
	for _, root := range roots {
		if strings.HasPrefix(pkg, root+"/") {
			return true
		}
	}
	return false
}

func copyableWithinPackage(t *types.Type, boundingDirs []string) bool {
	// If the type opts out of copy-generation, stop.
	if extractBoolTagOrDie("gencopy", true, t.CommentLines) == false {
		return false
	}
	// Only packages within the restricted range can be processed.
	if !isRootedUnder(t.Name.Package, boundingDirs) {
		return false
	}
	// TODO: Consider generating functions for other kinds too.
	if t.Kind != types.Struct {
		return false
	}
	// Also, filter out private types.
	if namer.IsPrivateGoName(t.Name.Name) {
		return false
	}
	return true
}

func (g *genDeepCopy) isOtherPackage(pkg string) bool {
	if pkg == g.targetPackage {
		return false
	}
	if strings.HasSuffix(pkg, "\""+g.targetPackage+"\"") {
		return false
	}
	return true
}

func (g *genDeepCopy) Imports(c *generator.Context) (imports []string) {
	importLines := []string{}
	for _, singleImport := range g.imports.ImportLines() {
		if g.isOtherPackage(singleImport) {
			importLines = append(importLines, singleImport)
		}
	}
	return importLines
}

func (g *genDeepCopy) withGlobals(args map[string]interface{}) map[string]interface{} {
	for k, v := range g.globalVariables {
		if _, ok := args[k]; !ok {
			args[k] = v
		}
	}
	return args
}

func argsFromType(t *types.Type) map[string]interface{} {
	return map[string]interface{}{
		"type": t,
	}
}

func (g *genDeepCopy) funcNameTmpl(t *types.Type) string {
	tmpl := "DeepCopy_$.type|public$"
	g.imports.AddType(t)
	if t.Name.Package != g.targetPackage {
		tmpl = g.imports.LocalNameOf(t.Name.Package) + "." + tmpl
	}
	return tmpl
}

func (g *genDeepCopy) Init(c *generator.Context, w io.Writer) error {
	cloner := c.Universe.Type(types.Name{Package: conversionPackagePath, Name: "Cloner"})
	g.imports.AddType(cloner)
	g.globalVariables = map[string]interface{}{
		"Cloner": cloner,
	}
	if !g.generateInitFunc {
		// TODO: We should come up with a solution to register all generated
		// deep-copy functions. However, for now, to avoid import cycles
		// we register only those explicitly requested.
		return nil
	}
	scheme := c.Universe.Variable(types.Name{Package: apiPackagePath, Name: "Scheme"})
	g.imports.AddType(scheme)
	g.globalVariables["scheme"] = scheme

	sw := generator.NewSnippetWriter(w, c, "$", "$")
	sw.Do("func init() {\n", nil)
	sw.Do("if err := $.scheme|raw$.AddGeneratedDeepCopyFuncs(\n", map[string]interface{}{
		"scheme": scheme,
	})
	for _, t := range g.typesForInit {
		sw.Do(fmt.Sprintf("%s,\n", g.funcNameTmpl(t)), argsFromType(t))
	}
	sw.Do("); err != nil {\n", nil)
	sw.Do("// if one of the deep copy functions is malformed, detect it immediately.\n", nil)
	sw.Do("panic(err)\n", nil)
	sw.Do("}\n", nil)
	sw.Do("}\n\n", nil)
	return sw.Error()
}

func (g *genDeepCopy) GenerateType(c *generator.Context, t *types.Type, w io.Writer) error {
	sw := generator.NewSnippetWriter(w, c, "$", "$")
	funcName := g.funcNameTmpl(t)
	sw.Do(fmt.Sprintf("func %s(in $.type|raw$, out *$.type|raw$, c *$.Cloner|raw$) error {\n", funcName), g.withGlobals(argsFromType(t)))
	g.generateFor(t, sw)
	sw.Do("return nil\n", nil)
	sw.Do("}\n\n", nil)
	return sw.Error()
}

// we use the system of shadowing 'in' and 'out' so that the same code is valid
// at any nesting level. This makes the autogenerator easy to understand, and
// the compiler shouldn't care.
func (g *genDeepCopy) generateFor(t *types.Type, sw *generator.SnippetWriter) {
	var f func(*types.Type, *generator.SnippetWriter)
	switch t.Kind {
	case types.Builtin:
		f = g.doBuiltin
	case types.Map:
		f = g.doMap
	case types.Slice:
		f = g.doSlice
	case types.Struct:
		f = g.doStruct
	case types.Interface:
		f = g.doInterface
	case types.Pointer:
		f = g.doPointer
	case types.Alias:
		f = g.doAlias
	default:
		f = g.doUnknown
	}
	f(t, sw)
}

func (g *genDeepCopy) doBuiltin(t *types.Type, sw *generator.SnippetWriter) {
	sw.Do("*out = in\n", nil)
}

func (g *genDeepCopy) doMap(t *types.Type, sw *generator.SnippetWriter) {
	sw.Do("*out = make($.|raw$)\n", t)
	if t.Key.IsAssignable() {
		switch {
		case hasDeepCopyMethod(t.Elem):
			sw.Do("for key, val := range in {\n", nil)
			sw.Do("(*out)[key] = val.DeepCopy()\n", nil)
			sw.Do("}\n", nil)
		case t.Elem.IsAnonymousStruct():
			sw.Do("for key := range in {\n", nil)
			sw.Do("(*out)[key] = struct{}{}\n", nil)
			sw.Do("}\n", nil)
		case t.Elem.IsAssignable():
			sw.Do("for key, val := range in {\n", nil)
			sw.Do("(*out)[key] = val\n", nil)
			sw.Do("}\n", nil)
		default:
			sw.Do("for key, val := range in {\n", nil)
			if g.copyableWithinPackage(t.Elem) {
				sw.Do("newVal := new($.|raw$)\n", t.Elem)
				funcName := g.funcNameTmpl(t.Elem)
				sw.Do(fmt.Sprintf("if err := %s(val, newVal, c); err != nil {\n", funcName), argsFromType(t.Elem))
				sw.Do("return err\n", nil)
				sw.Do("}\n", nil)
				sw.Do("(*out)[key] = *newVal\n", nil)
			} else {
				sw.Do("if newVal, err := c.DeepCopy(val); err != nil {\n", nil)
				sw.Do("return err\n", nil)
				sw.Do("} else {\n", nil)
				sw.Do("(*out)[key] = newVal.($.|raw$)\n", t.Elem)
				sw.Do("}\n", nil)
			}
			sw.Do("}\n", nil)
		}
	} else {
		// TODO: Implement it when necessary.
		sw.Do("for range in {\n", nil)
		sw.Do("// FIXME: Copying unassignable keys unsupported $.|raw$\n", t.Key)
		sw.Do("}\n", nil)
	}
}

func (g *genDeepCopy) doSlice(t *types.Type, sw *generator.SnippetWriter) {
	sw.Do("*out = make($.|raw$, len(in))\n", t)
	if t.Elem.Kind == types.Builtin {
		sw.Do("copy(*out, in)\n", nil)
	} else {
		sw.Do("for i := range in {\n", nil)
		if hasDeepCopyMethod(t.Elem) {
			sw.Do("(*out)[i] = in[i].DeepCopy()\n", nil)
		} else if t.Elem.IsAssignable() {
			sw.Do("(*out)[i] = in[i]\n", nil)
		} else if g.copyableWithinPackage(t.Elem) {
			funcName := g.funcNameTmpl(t.Elem)
			sw.Do(fmt.Sprintf("if err := %s(in[i], &(*out)[i], c); err != nil {\n", funcName), argsFromType(t.Elem))
			sw.Do("return err\n", nil)
			sw.Do("}\n", nil)
		} else {
			sw.Do("if newVal, err := c.DeepCopy(in[i]); err != nil {\n", nil)
			sw.Do("return err\n", nil)
			sw.Do("} else {\n", nil)
			sw.Do("(*out)[i] = newVal.($.|raw$)\n", t.Elem)
			sw.Do("}\n", nil)
		}
		sw.Do("}\n", nil)
	}
}

func (g *genDeepCopy) doStruct(t *types.Type, sw *generator.SnippetWriter) {
	for _, m := range t.Members {
		t := m.Type
		if t.Kind == types.Alias {
			copied := *t.Underlying
			copied.Name = t.Name
			t = &copied
		}
		args := map[string]interface{}{
			"type": t,
			"name": m.Name,
		}
		switch t.Kind {
		case types.Builtin:
			sw.Do("out.$.name$ = in.$.name$\n", args)
		case types.Map, types.Slice, types.Pointer:
			sw.Do("if in.$.name$ != nil {\n", args)
			sw.Do("in, out := in.$.name$, &out.$.name$\n", args)
			g.generateFor(t, sw)
			sw.Do("} else {\n", nil)
			sw.Do("out.$.name$ = nil\n", args)
			sw.Do("}\n", nil)
		case types.Struct:
			if hasDeepCopyMethod(t) {
				sw.Do("out.$.name$ = in.$.name$.DeepCopy()\n", args)
			} else if t.IsAssignable() {
				sw.Do("out.$.name$ = in.$.name$\n", args)
			} else if g.copyableWithinPackage(t) {
				funcName := g.funcNameTmpl(t)
				sw.Do(fmt.Sprintf("if err := %s(in.$.name$, &out.$.name$, c); err != nil {\n", funcName), args)
				sw.Do("return err\n", nil)
				sw.Do("}\n", nil)
			} else {
				sw.Do("if newVal, err := c.DeepCopy(in.$.name$); err != nil {\n", args)
				sw.Do("return err\n", nil)
				sw.Do("} else {\n", nil)
				sw.Do("out.$.name$ = newVal.($.type|raw$)\n", args)
				sw.Do("}\n", nil)
			}
		default:
			sw.Do("if in.$.name$ == nil {\n", args)
			sw.Do("out.$.name$ = nil\n", args)
			sw.Do("} else if newVal, err := c.DeepCopy(in.$.name$); err != nil {\n", args)
			sw.Do("return err\n", nil)
			sw.Do("} else {\n", nil)
			sw.Do("out.$.name$ = newVal.($.type|raw$)\n", args)
			sw.Do("}\n", nil)
		}
	}
}

func (g *genDeepCopy) doInterface(t *types.Type, sw *generator.SnippetWriter) {
	// TODO: Add support for interfaces.
	g.doUnknown(t, sw)
}

func (g *genDeepCopy) doPointer(t *types.Type, sw *generator.SnippetWriter) {
	sw.Do("*out = new($.Elem|raw$)\n", t)
	if hasDeepCopyMethod(t.Elem) {
		sw.Do("**out = in.DeepCopy()\n", nil)
	} else if t.Elem.IsAssignable() {
		sw.Do("**out = *in", nil)
	} else if g.copyableWithinPackage(t.Elem) {
		funcName := g.funcNameTmpl(t.Elem)
		sw.Do(fmt.Sprintf("if err := %s(*in, *out, c); err != nil {\n", funcName), argsFromType(t.Elem))
		sw.Do("return err\n", nil)
		sw.Do("}\n", nil)
	} else {
		sw.Do("if newVal, err := c.DeepCopy(*in); err != nil {\n", nil)
		sw.Do("return err\n", nil)
		sw.Do("} else {\n", nil)
		sw.Do("**out = newVal.($.|raw$)\n", t.Elem)
		sw.Do("}\n", nil)
	}
}

func (g *genDeepCopy) doAlias(t *types.Type, sw *generator.SnippetWriter) {
	// TODO: Add support for aliases.
	g.doUnknown(t, sw)
}

func (g *genDeepCopy) doUnknown(t *types.Type, sw *generator.SnippetWriter) {
	sw.Do("// FIXME: Type $.|raw$ is unsupported.\n", t)
}