package util

import (
	"bufio"
	"crypto/sha256"
	"errors"
	"fmt"
	"io"
	"os"
	"strings"

	"net/url"
	"path/filepath"

	"golang.org/x/term"
)

func Assert(condition bool) {
	if !condition {
		panic("assertion failed!")
	}
}

func Dirents(dir string) (entries []string, err error) {
	d, err := os.Open(dir)
	if err != nil {
		return nil, errors.New(err.Error())
	}

	names, err := d.Readdirnames(0)
	if err != nil {
		return nil, errors.New(err.Error())
	}

	for _, e := range names {
		entries = append(entries, e)
	}

	return
}

func DoChunks(f io.Reader, fun func (buf []byte)) (err error) {
	err = nil
	bytes, chunks := int64(0), int64(0)
	r := bufio.NewReader(f)
	buf := make([]byte, 0, 4*1024)

	for {
		var n int
		n, err = r.Read(buf[:cap(buf)])
		buf = buf[:n]
		if n == 0 {
			if err == nil {
				continue
			}
			if err == io.EOF {
				break
			}
			return
		}
		chunks++
		bytes += int64(len(buf))

		Assert(n == len(buf))
		fun(buf)

		if err != nil && err != io.EOF {
			return
		}
	}

	return
}

func EscapePath(path string) string {
	return strings.ReplaceAll(url.QueryEscape(path), "%2F", "/")
}

func HashOf(s string) string {
	h := sha256.New()
	h.Write([]byte(s))
	return fmt.Sprintf("%x", h.Sum(nil))
}

// print only if interactive
func Iprint(format string, args ...any) {
	if term.IsTerminal(int(os.Stderr.Fd())) {
		fmt.Fprintf(os.Stderr, format, args...)
	}
}

func MapToValues[Map ~map[K]V, K comparable, V any](m Map) (values []V) {
	for _, v := range m {
		values = append(values, v)
	}

	return
}

func OptionalString(cond bool, s string) string {
	if cond {
		return s
	}
	return ""
}

func Warn(format string, args ...any) {
	fmt.Fprintf(os.Stderr, "%s: %s\n",
		filepath.Base(os.Args[0]), fmt.Sprintf(format, args...))
}

func Die(format string, args ...any) {
	Warn(format, args...)
	os.Exit(1)
}