// FindQueryMethods locates all methods in the given package (assumed to be
// package database/sql) with a string parameter named "query".
func FindQueryMethods(sql *types.Package, ssa *ssa.Program) []*QueryMethod {
	methods := make([]*QueryMethod, 0)
	scope := sql.Scope()
	for _, name := range scope.Names() {
		o := scope.Lookup(name)
		if !o.Exported() {
			continue
		}
		if _, ok := o.(*types.TypeName); !ok {
			continue
		}
		n := o.Type().(*types.Named)
		for i := 0; i < n.NumMethods(); i++ {
			m := n.Method(i)
			if !m.Exported() {
				continue
			}
			s := m.Type().(*types.Signature)
			if num, ok := FuncHasQuery(s); ok {
				methods = append(methods, &QueryMethod{
					Func:     m,
					SSA:      ssa.FuncValue(m),
					ArgCount: s.Params().Len(),
					Param:    num,
				})
			}
		}
	}
	return methods
}

func (w *PkgWalker) LookupStructFromField(info *types.Info, cursorPkg *types.Package, cursorObj types.Object, cursorPos token.Pos) types.Object {
	if info == nil {
		conf := &PkgConfig{
			IgnoreFuncBodies: true,
			AllowBinary:      true,
			WithTestFiles:    true,
			Info: &types.Info{
				Defs: make(map[*ast.Ident]types.Object),
			},
		}
		w.imported[cursorPkg.Path()] = nil
		pkg, _ := w.Import("", cursorPkg.Path(), conf)
		if pkg != nil {
			info = conf.Info
		}
	}
	for _, obj := range info.Defs {
		if obj == nil {
			continue
		}
		if _, ok := obj.(*types.TypeName); ok {
			if t, ok := obj.Type().Underlying().(*types.Struct); ok {
				for i := 0; i < t.NumFields(); i++ {
					if t.Field(i).Pos() == cursorPos {
						return obj
					}
				}
			}
		}
	}
	return nil
}

func FindAllExports(pkg *types.Package, fset *token.FileSet) []UnexportCandidate {
	candidates := []UnexportCandidate{}
	for _, name := range pkg.Scope().Names() {
		obj := pkg.Scope().Lookup(name)
		if !obj.Exported() {
			continue
		}
		displayName := obj.Name()
		if _, ok := obj.(*types.Func); ok {
			displayName += "()"
		}
		candidate := UnexportCandidate{obj.Name(), displayName, fset.Position(obj.Pos())}
		candidates = append(candidates, candidate)
		if tn, ok := obj.(*types.TypeName); ok {
			if str, ok := tn.Type().Underlying().(*types.Struct); ok {
				candidates = append(candidates, findStructFields(str, obj.Name(), fset)...)
			}
			ptrType := types.NewPointer(tn.Type())
			methodSet := types.NewMethodSet(ptrType)
			for i := 0; i < methodSet.Len(); i++ {
				methodSel := methodSet.At(i)
				method := methodSel.Obj()
				// skip unexported functions, and functions from embedded fields.
				// The best I can figure out for embedded functions is if the selection index path is longer than 1.
				if !method.Exported() || len(methodSel.Index()) > 1 {
					continue
				}
				candidate := UnexportCandidate{method.Name(), obj.Name() + "." + method.Name() + "()", fset.Position(method.Pos())}
				candidates = append(candidates, candidate)
			}
		}
	}
	return candidates
}

func IsSamePkg(a, b *types.Package) bool {
	if a == b {
		return true
	}
	if a == nil || b == nil {
		return false
	}
	return a.Path() == b.Path()
}

func (w *PkgWalker) LookupImport(pkg *types.Package, pkgInfo *types.Info, cursor *FileCursor, is *ast.ImportSpec) {
	fpath, err := strconv.Unquote(is.Path.Value)
	if err != nil {
		return
	}

	if typesFindDef {
		fmt.Println(w.fset.Position(is.Pos()))
	}

	fbase := fpath
	pos := strings.LastIndexAny(fpath, "./-\\")
	if pos != -1 {
		fbase = fpath[pos+1:]
	}

	var fname string
	if is.Name != nil {
		fname = is.Name.Name
	} else {
		fname = fbase
	}

	if typesFindInfo {
		if fname == fpath {
			fmt.Printf("package %s\n", fname)
		} else {
			fmt.Printf("package %s (\"%s\")\n", fname, fpath)
		}
	}

	if !typesFindUse {
		return
	}

	path := pkg.Path()

	if strings.Contains(path, "vendor/") {
		path = strings.Split(path, "vendor/")[1]
	}

	fid := path + "." + fname

	var usages []int
	for id, obj := range pkgInfo.Uses {
		if obj != nil && obj.Id() == fid { //!= nil && cursorObj.Pos() == obj.Pos() {
			usages = append(usages, int(id.Pos()))
		}
	}

	(sort.IntSlice(usages)).Sort()
	for _, pos := range usages {
		fmt.Println(w.fset.Position(token.Pos(pos)))
	}
}

func (c *funcContext) pkgVar(pkg *types.Package) string {
	if pkg == c.p.Pkg {
		return "$pkg"
	}

	pkgVar, found := c.p.pkgVars[pkg.Path()]
	if !found {
		pkgVar = fmt.Sprintf(`$packages["%s"]`, pkg.Path())
	}
	return pkgVar
}

// pkgString returns a string representation of a package's exported interface.
func pkgString(pkg *types.Package) string {
	var buf bytes.Buffer

	fmt.Fprintf(&buf, "package %s\n", pkg.Name())

	scope := pkg.Scope()
	for _, name := range scope.Names() {
		if exported(name) {
			obj := scope.Lookup(name)
			buf.WriteString(obj.String())

			switch obj := obj.(type) {
			case *types.Const:
				// For now only print constant values if they are not float
				// or complex. This permits comparing go/types results with
				// gc-generated gcimported package interfaces.
				info := obj.Type().Underlying().(*types.Basic).Info()
				if info&types.IsFloat == 0 && info&types.IsComplex == 0 {
					fmt.Fprintf(&buf, " = %s", obj.Val())
				}

			case *types.TypeName:
				// Print associated methods.
				// Basic types (e.g., unsafe.Pointer) have *types.Basic
				// type rather than *types.Named; so we need to check.
				if typ, _ := obj.Type().(*types.Named); typ != nil {
					if n := typ.NumMethods(); n > 0 {
						// Sort methods by name so that we get the
						// same order independent of whether the
						// methods got imported or coming directly
						// for the source.
						// TODO(gri) This should probably be done
						// in go/types.
						list := make([]*types.Func, n)
						for i := 0; i < n; i++ {
							list[i] = typ.Method(i)
						}
						sort.Sort(byName(list))

						buf.WriteString("\nmethods (\n")
						for _, m := range list {
							fmt.Fprintf(&buf, "\t%s\n", m)
						}
						buf.WriteString(")")
					}
				}
			}
			buf.WriteByte('\n')
		}
	}

	return buf.String()
}

func declTypeName(pkg *types.Package, name string) *types.TypeName {
	scope := pkg.Scope()
	if obj := scope.Lookup(name); obj != nil {
		return obj.(*types.TypeName)
	}
	obj := types.NewTypeName(token.NoPos, pkg, name, nil)
	// a named type may be referred to before the underlying type
	// is known - set it up
	types.NewNamed(obj, nil, nil)
	scope.Insert(obj)
	return obj
}

func (r *renamer) checkExport(id *ast.Ident, pkg *types.Package, from types.Object) bool {
	// Reject cross-package references if r.to is unexported.
	// (Such references may be qualified identifiers or field/method
	// selections.)
	if !ast.IsExported(r.to) && pkg != from.Pkg() {
		r.errorf(from.Pos(),
			"renaming this %s %q to %q would make it unexported",
			objectKind(from), from.Name(), r.to)
		r.errorf(id.Pos(), "\tbreaking references from packages such as %q",
			pkg.Path())
		return false
	}
	return true
}

func walkPkg(typpkg *types.Package, docpkg *doc.Package, f func(*types.Struct, *types.TypeName, *doc.Package)) {
	for _, name := range typpkg.Scope().Names() {
		obj := typpkg.Scope().Lookup(name)

		if typename, ok := obj.(*types.TypeName); ok {
			named := typename.Type().(*types.Named)

			if strukt, ok := named.Underlying().(*types.Struct); ok && strukt.NumFields() > 0 && strukt.Field(0).Name() == "TypeMeta" {
				if len(os.Args) == 3 || os.Args[3] == typename.Name() {
					f(strukt, typename, docpkg)
				}
			}
		}
	}
}

// BuildPackage builds an SSA program with IR for a single package.
//
// It populates pkg by type-checking the specified file ASTs.  All
// dependencies are loaded using the importer specified by tc, which
// typically loads compiler export data; SSA code cannot be built for
// those packages.  BuildPackage then constructs an ssa.Program with all
// dependency packages created, and builds and returns the SSA package
// corresponding to pkg.
//
// The caller must have set pkg.Path() to the import path.
//
// The operation fails if there were any type-checking or import errors.
//
// See ../ssa/example_test.go for an example.
//
func BuildPackage(tc *types.Config, fset *token.FileSet, pkg *types.Package, files []*ast.File, mode ssa.BuilderMode) (*ssa.Package, *types.Info, error) {
	if fset == nil {
		panic("no token.FileSet")
	}
	if pkg.Path() == "" {
		panic("package has no import path")
	}

	info := &types.Info{
		Types:      make(map[ast.Expr]types.TypeAndValue),
		Defs:       make(map[*ast.Ident]types.Object),
		Uses:       make(map[*ast.Ident]types.Object),
		Implicits:  make(map[ast.Node]types.Object),
		Scopes:     make(map[ast.Node]*types.Scope),
		Selections: make(map[*ast.SelectorExpr]*types.Selection),
	}
	if err := types.NewChecker(tc, fset, pkg, info).Files(files); err != nil {
		return nil, nil, err
	}

	prog := ssa.NewProgram(fset, mode)

	// Create SSA packages for all imports.
	// Order is not significant.
	created := make(map[*types.Package]bool)
	var createAll func(pkgs []*types.Package)
	createAll = func(pkgs []*types.Package) {
		for _, p := range pkgs {
			if !created[p] {
				created[p] = true
				prog.CreatePackage(p, nil, nil, true)
				createAll(p.Imports())
			}
		}
	}
	createAll(pkg.Imports())

	// Create and build the primary package.
	ssapkg := prog.CreatePackage(pkg, files, info, false)
	ssapkg.Build()
	return ssapkg, info, nil
}

func defaultFileName(lang string, pkg *types.Package) string {
	if *outdir == "" {
		return ""
	}

	switch lang {
	case "java":
		firstRune, size := utf8.DecodeRuneInString(pkg.Name())
		className := string(unicode.ToUpper(firstRune)) + pkg.Name()[size:]
		return filepath.Join(*outdir, className+".java")
	case "go":
		return filepath.Join(*outdir, "go_"+pkg.Name()+".go")
	case "objc":
		firstRune, size := utf8.DecodeRuneInString(pkg.Name())
		className := string(unicode.ToUpper(firstRune)) + pkg.Name()[size:]
		return filepath.Join(*outdir, "Go"+className+".m")
	}
	errorf("unknown target language: %q", lang)
	os.Exit(exitStatus)
	return ""
}

func (p *importer) obj(pkg *types.Package) {
	var obj types.Object
	switch tag := p.int(); tag {
	case constTag:
		obj = types.NewConst(token.NoPos, pkg, p.string(), p.typ(), p.value())
	case typeTag:
		// type object is added to scope via respective named type
		_ = p.typ().(*types.Named)
		return
	case varTag:
		obj = types.NewVar(token.NoPos, pkg, p.string(), p.typ())
	case funcTag:
		obj = types.NewFunc(token.NoPos, pkg, p.string(), p.typ().(*types.Signature))
	default:
		panic(fmt.Sprintf("unexpected object tag %d", tag))
	}

	if alt := pkg.Scope().Insert(obj); alt != nil {
		panic(fmt.Sprintf("%s already declared", alt.Name()))
	}
}

//!+
func PrintSkeleton(pkg *types.Package, ifacename, concname string) error {
	obj := pkg.Scope().Lookup(ifacename)
	if obj == nil {
		return fmt.Errorf("%s.%s not found", pkg.Path(), ifacename)
	}
	if _, ok := obj.(*types.TypeName); !ok {
		return fmt.Errorf("%v is not a named type", obj)
	}
	iface, ok := obj.Type().Underlying().(*types.Interface)
	if !ok {
		return fmt.Errorf("type %v is a %T, not an interface",
			obj, obj.Type().Underlying())
	}
	// Use first letter of type name as receiver parameter.
	if !isValidIdentifier(concname) {
		return fmt.Errorf("invalid concrete type name: %q", concname)
	}
	r, _ := utf8.DecodeRuneInString(concname)

	fmt.Printf("// *%s implements %s.%s.\n", concname, pkg.Path(), ifacename)
	fmt.Printf("type %s struct{}\n", concname)
	mset := types.NewMethodSet(iface)
	for i := 0; i < mset.Len(); i++ {
		meth := mset.At(i).Obj()
		sig := types.TypeString(meth.Type(), (*types.Package).Name)
		fmt.Printf("func (%c *%s) %s%s {\n\tpanic(\"unimplemented\")\n}\n",
			r, concname, meth.Name(),
			strings.TrimPrefix(sig, "func"))
	}
	return nil
}

func (p *exporter) pkg(pkg *types.Package) {
	if trace {
		p.tracef("package { ")
		defer p.tracef("} ")
	}

	if pkg == nil {
		panic("unexpected nil pkg")
	}

	// if the package was seen before, write its index (>= 0)
	if i, ok := p.pkgIndex[pkg]; ok {
		p.int(i)
		return
	}
	p.pkgIndex[pkg] = len(p.pkgIndex)

	// otherwise, write the package tag (< 0) and package data
	p.int(packageTag)
	p.string(pkg.Name())
	p.string(pkg.Path())
}

func findFromObjects(iprog *loader.Program, spec *spec) ([]types.Object, error) {
	if spec.filename != "" {
		return findFromObjectsInFile(iprog, spec)
	}

	// Search for objects defined in specified package.

	// TODO(adonovan): the iprog.ImportMap has an entry {"main": ...}
	// for main packages, even though that's not an import path.
	// Seems like a bug.
	//
	// pkg := iprog.ImportMap[spec.pkg]
	// if pkg == nil {
	// 	return fmt.Errorf("cannot find package %s", spec.pkg) // can't happen?
	// }
	// info := iprog.AllPackages[pkg]

	// Workaround: lookup by value.
	var info *loader.PackageInfo
	var pkg *types.Package
	for pkg, info = range iprog.AllPackages {
		if pkg.Path() == spec.pkg {
			break
		}
	}
	if info == nil {
		return nil, fmt.Errorf("package %q was not loaded", spec.pkg)
	}

	objects, err := findObjects(info, spec)
	if err != nil {
		return nil, err
	}
	if len(objects) > 1 {
		// ambiguous "*" scope query
		return nil, ambiguityError(iprog.Fset, objects)
	}
	return objects, nil
}

// ExportData serializes the interface (exported package objects)
// of package pkg and returns the corresponding data. The export
// format is described elsewhere (TODO).
func ExportData(pkg *types.Package) []byte {
	p := exporter{
		data:     append([]byte(magic), format()),
		pkgIndex: make(map[*types.Package]int),
		typIndex: make(map[types.Type]int),
	}

	// populate typIndex with predeclared types
	for _, t := range predeclared {
		p.typIndex[t] = len(p.typIndex)
	}

	if trace {
		p.tracef("export %s\n", pkg.Name())
		defer p.tracef("\n")
	}

	p.string(version)

	p.pkg(pkg)

	// collect exported objects from package scope
	var list []types.Object
	scope := pkg.Scope()
	for _, name := range scope.Names() {
		if exported(name) {
			list = append(list, scope.Lookup(name))
		}
	}

	// write objects
	p.int(len(list))
	for _, obj := range list {
		p.obj(obj)
	}

	return p.data
}

// Structure computes the structure of the lexical environment of the
// package specified by (pkg, info, files).
//
// The info.{Types,Defs,Uses,Implicits} maps must have been populated
// by the type-checker
//
// fset is used for logging.
//
func Structure(fset *token.FileSet, pkg *types.Package, info *types.Info, files []*ast.File) *Info {
	r := resolver{
		fset:    fset,
		imports: make(map[string]*types.Package),
		result: &Info{
			Defs:   make(map[types.Object]*Block),
			Refs:   make(map[types.Object][]Reference),
			Blocks: make(map[ast.Node]*Block),
		},
		pkg:  pkg,
		info: info,
	}

	// Build import map for just this package.
	r.imports["unsafe"] = types.Unsafe
	for _, imp := range pkg.Imports() {
		r.imports[imp.Path()] = imp
	}

	r.doPackage(pkg, files)

	return r.result
}

func (p *Processor) processPackage(pkg *Package, typesPkg *types.Package) {
	pkg.Models = make([]*Model, 0)
	pkg.Structs = make([]string, 0)
	pkg.Functions = make([]string, 0)

	s := typesPkg.Scope()
	for _, name := range s.Names() {
		fun := p.tryGetFunction(s.Lookup(name))
		if fun != nil {
			pkg.Functions = append(pkg.Functions, name)
		}

		str := p.tryGetStruct(s.Lookup(name).Type())
		if str == nil {
			continue
		}

		if m := p.processStruct(name, str); m != nil {
			pkg.Models = append(pkg.Models, m)
		} else {
			pkg.Structs = append(pkg.Structs, name)
		}
	}
}

// NewPackageDef creates a new Def that represents a Go package.
func (g *Grapher) NewPackageDef(pkgInfo *loader.PackageInfo, pkg *types.Package) (*Def, error) {
	var pkgDir string
	if len(pkgInfo.Files) > 0 {
		pkgDir = filepath.Dir(g.program.Fset.Position(pkgInfo.Files[0].Package).Filename)
	}

	return &Def{
		Name: pkg.Name(),

		DefKey: &DefKey{PackageImportPath: pkg.Path(), Path: []string{}},

		File: pkgDir,

		DefInfo: definfo.DefInfo{
			Exported: true,
			PkgName:  pkg.Name(),
			Kind:     definfo.Package,
		},
	}, nil
}