parser.go

// Package easyparser provides a Go module parser for AST
package easyparser

import (
	"fmt"
	"go/token"
	"go/types"
	"path/filepath"
	"reflect"

	tstypes "github.com/go-generalize/go-easyparser/types"
	"github.com/go-utils/gopackages"
	"golang.org/x/tools/go/packages"
)

// Parser is a Go module parser for TypeScript AST
type Parser struct {
	pkgs []*packages.Package

	types       map[string]tstypes.Type
	consts      map[string][]constCandidate
	basePackage string

	Filter   func(opt *FilterOpt) bool
	Replacer func(t types.Type) tstypes.Type
	// ForceMapNonNullable provides backward compatibility to interpret map as non-nullable
	ForceMapNonNullable bool
	// IgnoreOmittedJSONField is a flag to ignore omitted json fields
	IgnoreOmittedJSONField bool
}

func getPackagePath(dir string) (root string, pkg string, err error) {
	goModPath, err := gopackages.GetGoModPath(dir)

	if err != nil {
		return "", "", err
	}
	goModDir := filepath.Dir(goModPath)

	mod, err := gopackages.GetGoModule(goModPath)

	if err != nil {
		return "", "", err
	}

	abs, err := filepath.Abs(dir)

	if err != nil {
		return "", "", err
	}

	rel, err := filepath.Rel(goModDir, abs)

	if err != nil {
		return "", "", err
	}

	return goModDir, filepath.Join(mod, "/"+rel), nil
}

// NewParser initializes a new Parser
func NewParser(dir string, filter func(*FilterOpt) bool) (*Parser, error) {
	root, pkg, err := getPackagePath(dir)

	if err != nil {
		return nil, err
	}

	cfg := &packages.Config{
		Mode: packages.NeedName |
			packages.NeedCompiledGoFiles |
			packages.NeedSyntax |
			packages.NeedTypes |
			packages.NeedTypesInfo,
		Dir: root,
	}

	pkgs, err := packages.Load(cfg, pkg)

	if err != nil {
		return nil, err
	}

	if err := visitErrors(pkgs); err != nil {
		return nil, err
	}

	return &Parser{
		pkgs:        pkgs,
		basePackage: pkg,
		Filter:      filter,
	}, nil
}

func (p *Parser) exported(t *types.Named, dep bool) bool {
	opt := &FilterOpt{
		BasePackage: false,
		Package:     t.Obj().Pkg().String(),
		Name:        t.Obj().Name(),
		Exported:    t.Obj().Exported(),
		Dependency:  dep,
	}
	packages.Visit(p.pkgs, nil, func(pkg *packages.Package) {
		if pkg.Types.Scope() == t.Obj().Parent() {
			opt.BasePackage = true
		}
	})

	return p.Filter(opt)
}

func (p *Parser) isStruct(u types.Type) bool {
	_, ok := u.(*types.Struct)

	return ok
}

// Parse parses the Go module and returns ASTs
func (p *Parser) Parse() (res map[string]tstypes.Type, err error) {
	defer func() {
		if e := recover(); e != nil {
			var ok bool
			err, ok = e.(error)

			if !ok {
				err = fmt.Errorf("%+v", e)
			}
		}
	}()

	p.types = make(map[string]tstypes.Type)
	p.consts = make(map[string][]constCandidate)

	// parse const
	packages.Visit(p.pkgs, nil, func(pkg *packages.Package) {
		for _, obj := range pkg.TypesInfo.Defs {
			if obj == nil {
				continue
			}

			if obj.Parent() != pkg.Types.Scope() {
				continue
			}

			switch v := obj.(type) {
			case *types.Const: // const a = 1
				p.parseConst(v)
			}
		}
	})

	// parse types
	packages.Visit(p.pkgs, nil, func(pkg *packages.Package) {
		for _, obj := range pkg.TypesInfo.Defs {
			if obj == nil {
				continue
			}

			if obj.Parent() != pkg.Types.Scope() {
				continue
			}

			v, ok := obj.(*types.TypeName)
			if !(ok && !v.IsAlias()) {
				continue
			}

			t, ok := v.Type().(*types.Named)

			if !ok {
				continue
			}

			pp := &pkgParser{
				Parser: p,
				pkg:    pkg.Types,
				fset:   pkg.Fset,
			}

			parsed := pp.parseType(t, false)

			if parsed == nil {
				continue
			}
			parsed.SetPackageName(pkg.Name)
		}
	})

	p.sortConst()

	return p.types, nil
}

// GetBasePackage returns a base module for the root package
func (p *Parser) GetBasePackage() string {
	return p.basePackage
}

// pkgParser parses a types.Package
type pkgParser struct {
	*Parser
	pkg  *types.Package
	fset *token.FileSet
}

func (p *pkgParser) parseNamed(t *types.Named, dep bool) tstypes.Type {
	if t.Obj().Type().Underlying().String() == "struct{wall uint64; ext int64; loc *time.Location}" {
		return &tstypes.Date{}
	}

	if t.String() == "time.Time" {
		return &tstypes.Date{}
	}

	exported := p.exported(t, dep)

	if exported {
		tt, ok := p.types[t.String()]

		if ok {
			return tt
		}
	} else if !dep {
		return nil
	}

	// For recursive references to the same struct
	var dummy *tstypes.Object
	if exported && p.isStruct(t.Underlying()) {
		dummy = &tstypes.Object{}
		p.types[t.String()] = dummy
	}

	typ := p.parseType(t.Underlying(), true)

	if dummy != nil {
		//nolint
		obj := typ.(*tstypes.Object)

		dummy.Entries = obj.Entries
		typ = dummy
	}

	if exported {
		if typ, ok := typ.(tstypes.Enumerable); ok {
			consts := p.consts[t.String()]

			for i := range consts {
				typ.AddCandidates(consts[i].Key, consts[i].Value)
			}
		}

		if named, ok := typ.(tstypes.NamedType); ok {
			named.SetName(t.String())
		}

		pos := p.fset.Position(t.Obj().Pos())
		typ.SetPosition(&pos)

		p.types[t.String()] = typ
	}

	return typ
}

func (p *pkgParser) parsePointer(u *types.Pointer) tstypes.Type {
	return &tstypes.Nullable{
		Inner: p.parseType(u.Elem(), true),
	}
}

func (p *pkgParser) parseSlice(u *types.Slice) tstypes.Type {
	if basic, ok := u.Elem().(*types.Basic); ok && basic.Kind() == types.Byte {
		return &tstypes.Nullable{
			Inner: &tstypes.String{},
		}
	}

	return &tstypes.Nullable{
		Inner: &tstypes.Array{
			Inner: p.parseType(u.Elem(), true),
		},
	}
}

func (p *pkgParser) parseArray(u *types.Array) tstypes.Type {
	return &tstypes.Array{
		Inner: p.parseType(u.Elem(), true),
	}
}

func (p *pkgParser) parseMap(u *types.Map) tstypes.Type {
	keyType := p.parseType(u.Key(), true)

	if !keyType.UsedAsMapKey() {
		panic(keyType.String() + " cannot be used as key")
	}

	if p.ForceMapNonNullable {
		return &tstypes.Map{
			Key:   keyType,
			Value: p.parseType(u.Elem(), true),
		}
	}

	return &tstypes.Nullable{
		Inner: &tstypes.Map{
			Key:   keyType,
			Value: p.parseType(u.Elem(), true),
		},
	}
}

func (p *pkgParser) parseInterface(_ *types.Interface) tstypes.Type {
	return &tstypes.Any{}
}

func (p *pkgParser) parseType(u types.Type, dep bool) tstypes.Type {
	var typ tstypes.Type
	if p.Replacer != nil {
		typ = p.Replacer(u)

		if typ != nil {
			return typ
		}
	}

	switch u := u.(type) {
	case *types.Named:
		typ = p.parseNamed(u, dep)
	case *types.Struct:
		typ = p.parseStruct(u)
	case *types.Basic:
		typ = p.parseBasic(u)
	case *types.Pointer:
		typ = p.parsePointer(u)
	case *types.Slice:
		typ = p.parseSlice(u)
	case *types.Array:
		typ = p.parseArray(u)
	case *types.Map:
		typ = p.parseMap(u)
	case *types.Interface:
		typ = p.parseInterface(u)
	default:
		panic("unsupported named type: " + reflect.TypeOf(u).String())
	}

	return typ
}