// 离线列出模块内非测试 Go 文件的导入。
// 只使用标准库，跳过 _test.go 和带 go.mod 的子目录，避免 go list 去下载模块图。
package main

import (
	"bufio"
	"fmt"
	"go/parser"
	"go/token"
	"os"
	"path/filepath"
	"strings"
)

func main() {
	for _, root := range os.Args[1:] {
		mod := modulePath(filepath.Join(root, "go.mod"))
		if mod == "" {
			fmt.Fprintf(os.Stderr, "lint-imports: %s has no module path\n", root)
			os.Exit(1)
		}
		err := filepath.WalkDir(root, func(path string, d os.DirEntry, err error) error {
			if err != nil || !d.IsDir() {
				return nil
			}
			name := d.Name()
			if name == "vendor" || (name != "." && strings.HasPrefix(name, ".")) {
				return filepath.SkipDir
			}
			if path != root {
				if _, statErr := os.Stat(filepath.Join(path, "go.mod")); statErr == nil {
					return filepath.SkipDir
				}
			}
			return printImports(root, mod, path)
		})
		if err != nil {
			fmt.Fprintf(os.Stderr, "lint-imports: %v\n", err)
			os.Exit(1)
		}
	}
}

func modulePath(goMod string) string {
	f, err := os.Open(goMod)
	if err != nil {
		return ""
	}
	defer f.Close()
	sc := bufio.NewScanner(f)
	for sc.Scan() {
		fields := strings.Fields(sc.Text())
		if len(fields) >= 2 && fields[0] == "module" {
			return fields[1]
		}
	}
	return ""
}

func printImports(root, mod, dir string) error {
	rel, err := filepath.Rel(root, dir)
	if err != nil {
		return err
	}
	importer := mod
	if rel != "." {
		importer = mod + "/" + filepath.ToSlash(rel)
	}
	entries, err := os.ReadDir(dir)
	if err != nil {
		return err
	}
	fset := token.NewFileSet()
	seen := map[string]struct{}{}
	var imports []string
	for _, entry := range entries {
		name := entry.Name()
		if entry.IsDir() || !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
			continue
		}
		file, err := parser.ParseFile(fset, filepath.Join(dir, name), nil, parser.ImportsOnly)
		if err != nil {
			continue
		}
		for _, imp := range file.Imports {
			path := strings.Trim(imp.Path.Value, `"`)
			if _, ok := seen[path]; ok {
				continue
			}
			seen[path] = struct{}{}
			imports = append(imports, path)
		}
	}
	if len(imports) == 0 {
		return nil
	}
	fmt.Printf("%s %s\n", importer, strings.Join(imports, " "))
	return nil
}