package main

import (
	"bytes"
	"fmt"
	"github.com/bmatcuk/doublestar/v4"
	"golang.org/x/mod/module"
	"golang.org/x/mod/zip"
	"io"
	"log"
	"os"
	"path"
	"path/filepath"
	"slices"
	"strings"
)

type dirFile struct {
	filePath, slashPath string
	info                os.FileInfo
}

func (f dirFile) Path() string                 { return f.slashPath }
func (f dirFile) Lstat() (os.FileInfo, error)  { return f.info, nil }
func (f dirFile) Open() (io.ReadCloser, error) { return os.Open(f.filePath) }

func parseGitignore(wd string) []string {
	f := make([]string, 0)
	file, err := os.ReadFile(path.Join(wd, ".gitignore"))
	if err == nil {
		str := bytes.NewBuffer(file).String()
		for _, rline := range strings.Split(str, "\n") {
			line := strings.TrimSpace(rline)
			if line == "" || strings.HasPrefix(line, "#") || strings.HasPrefix(line, "!") {
				continue
			}
			if strings.HasPrefix(line, "*") {
				f = append(f, line)
				f = append(f, fmt.Sprintf("**/%s", line))
			} else if strings.HasSuffix(line, "/") {
				f = append(f, fmt.Sprintf("%s/**", line))
				f = append(f, fmt.Sprintf("%s/**/*", line))
			}
		}
	}
	fmt.Println(f)
	return f
}

func doWalk(wd string, exGlobs []string) []zip.File {
	f := make([]zip.File, 0)
	filepath.Walk(wd, func(p string, info os.FileInfo, err error) error {
		slashed := filepath.ToSlash(p)
		rel, _ := filepath.Rel(wd, slashed)
		rel = filepath.ToSlash(rel)
		if info.IsDir() {
			if p == wd {
				return nil
			}
			switch filepath.Base(p) {
			case ".git", ".bzr", ".svn", ".hg":
				return filepath.SkipDir
			}
			if goModInfo, err := os.Lstat(filepath.Join(p, "go.mod")); err == nil && !goModInfo.IsDir() {
				return filepath.SkipDir
			}
			for _, pat := range exGlobs {

				ok, _ := doublestar.Match(pat, rel)
				if ok {
					return filepath.SkipDir
				}
			}

			return nil
		}
		if !info.Mode().IsRegular() {
			return nil
		}

		ok, err := doublestar.Match(fmt.Sprintf("{%s}", strings.Join(exGlobs, ",")), rel)
		if err != nil {
			log.Fatal(err)
		}
		if !ok {
			if !slices.Contains(maps(f, func(t zip.File) string {
				return t.Path()
			}), slashed) {
				f = append(f, dirFile{
					filePath:  p,
					info:      info,
					slashPath: rel,
				})
			}
		}

		return nil
	})

	return f
}

func maps[T any, R any](slice []T, fn func(t T) R) []R {
	ret := make([]R, 0)
	for _, e := range slice {
		ret = append(ret, fn(e))
	}
	return ret
}

func main() {
	args := os.Args[1:]
	if len(args) < 3 {
		log.Fatal("usage: PACKAGE-NAME VERSION PATH [EXCLUSION-GLOBS...]")
	}
	version := args[1]
	if !strings.HasPrefix(version, "v") {
		version = fmt.Sprintf("v%s", version)
	}

	var absPath string
	absPath, _ = filepath.Abs(args[2])
	excludeGlobs := make([]string, 0)
	excludeGlobs = append(excludeGlobs, ".*/*", "build/**")
	excludeGlobs = append(excludeGlobs, parseGitignore(absPath)...)
	if len(args) >= 4 {
		excludeGlobs = append(excludeGlobs, args[3:]...)
	}

	buildFile := fmt.Sprintf(filepath.Join(absPath, "build", "%s.zip"), version)
	walked := doWalk(absPath, excludeGlobs)
	_ = os.Remove(buildFile)
	f, _ := os.Create(buildFile)
	err := zip.Create(f, module.Version{
		Version: version,
		Path:    args[0],
	}, walked)
	if err != nil {
		log.Fatal(err)
	}
}