import (
	"go/ast"
	"go/parser"
	"go/token"
	"gop/env"
	"runtime"
)

type exargs struct {
	N    int
	Code string
}

var (
	Pkg    string
	Name   string
	Exargs *exargs
)

func .toFuncType(t *ast.FuncType, at string) *ast.FuncType {
	return {
		Params:  t.Params,
		Results: toParams(t.Results, at),
	}
}

func .toMethodType(t *ast.FuncType, ex *exargs, at string) (mt *ast.FuncType, recvType ast.Expr) {
	list := t.Params.List
	first := list[0]
	recvType = first.Type
	if len(first.Names) == 1 {
		list = list[1:]
	} else {
		list[0] = {
			Doc:     first.Doc,
			Names:   first.Names[1:],
			Type:    recvType,
			Comment: first.Comment,
		}
	}
	mt = {
		Params:  {List: rmExargs(list, ex)},
		Results: toParams(t.Results, at),
	}
	return
}

var (
	fset    = token.newFileSet
	pkgs    = map[string]*ast.Package{}
	root    = env.GOPROOT()
	goroot  = runtime.GOROOT()
	pkgDirs = {
		"":        "${goroot}/src/builtin",
		"fmt":     "${goroot}/src/fmt",
		"os":      "${goroot}/src/os",
		"reflect": "${goroot}/src/reflect",
		"strconv": "${goroot}/src/strconv",
		"strings": "${goroot}/src/strings",

		"buil":        "${root}/builtin",
		"iox":         "${root}/builtin/iox",
		"stringslice": "${root}/builtin/stringslice",
		"strx":        "${root}/../x/stringutil",
	}
)

func getAST() *ast.FuncDecl {
	name := Name
	if Pkg == "" {
		name = name.trimPrefix("bto").toLower
	}
	pkg := reference.pkgOf(Pkg)
	return reference.funcDecl(pkg, name)
}

func .funcDecl(pkg *ast.Package, name string) *ast.FuncDecl {
	for file <- pkg.Files {
		for decl <- file.Decls {
			if fn, ok := decl.(*ast.FuncDecl); ok && fn.Name.Name == name {
				return fn
			}
		}
	}
	panic("function not found: ${pkg.Name}.${name}")
}

func .pkgOf(pkgPath string) *ast.Package {
	if pkg, ok := pkgs[pkgPath]; ok {
		return pkg
	}

	dir, ok := pkgDirs[pkgPath]
	if !ok {
		panic("unknown package: ${pkgPath}")
	}

	for name, pkg <- parser.parseDir(fset, dir, nil, parser.ParseComments)! {
		if name.hasSuffix("_test") {
			continue
		}
		pkgs[pkgPath] = pkg
		return pkg
	}
	panic("package not found: ${pkgPath}")
}