package main

import (
	"bytes"
	"compress/gzip"
	"fmt"
	"go.etcd.io/bbolt"
	"io"
	"io/fs"
	"os"
	"path/filepath"
	"strings"
)

func main() {
	if len(os.Args) != 3 {
		fmt.Println("Usage: generate <source> <output>")
		os.Exit(1)
	}

	source := os.Args[1]
	output := os.Args[2]
	if _, err := os.Stat(filepath.Dir(output)); err != nil {
		if os.IsNotExist(err) {
			if err = os.MkdirAll(filepath.Dir(output), 0755); err != nil {
				panic(err)
			}
		}
	}

	temp := "/tmp/chameleon.templates"
	defer os.RemoveAll(temp)

	tempDB, err := bbolt.Open(temp, 0640, nil)
	if err != nil {
		panic(err)
	}
	defer tempDB.Close()

	_ = os.Remove(output)
	db, err := bbolt.Open(output, 0644, nil)
	if err != nil {
		panic(err)
	}
	defer db.Close()

	err = tempDB.Update(func(tx *bbolt.Tx) error {
		var bkt *bbolt.Bucket
		if bkt, err = tx.CreateBucketIfNotExists([]byte("templates")); err != nil {
			return err
		}

		return filepath.WalkDir(source, func(path string, d fs.DirEntry, err error) error {
			if d == nil || d.IsDir() {
				return nil
			}

			if !strings.HasSuffix(path, ".yaml") {
				return nil
			}

			var file *os.File
			if file, err = os.Open(path); err != nil {
				return err
			}

			var buf bytes.Buffer
			writer := gzip.NewWriter(&buf)
			_, err = io.Copy(writer, file)
			_ = file.Close()
			_ = writer.Close()
			if err != nil {
				return err
			}

			key := strings.TrimPrefix(path, source)
			return bkt.Put([]byte(key), buf.Bytes())
		})
	})
	if err != nil {
		panic(err)
	}

	if err = bbolt.Compact(db, tempDB, 0); err != nil {
		panic(err)
	}
}